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Sample records for air kerma strength

  1. Evaluation and test of 192Ir air kerma strength for afterloading systems

    International Nuclear Information System (INIS)

    Objective: To study the method of measuring air kerma strength of afterloading units with 192Ir source by using well type ionization chamber. Methods: The air kerma strength of 30 afterloading units with 192Ir source was measured using 2000A electrometer and 1000 plus well type ionization chamber, and apparent activity of the source was calculated with the air kerma strength and apparent activity conversion factor. The measured activity of the source was compared with the original value of the source provided by the manufacturer, and the relevant deviation should be within ±5%. Results: The air kerma strength of afterloading units with 192Ir sources was tested. The relevant deviation of the measured activity and the original value was within -0.1%-4.4%. Conclusions: The measurement method with a well type ionization chamber is convenient and highly accurate which can be used for the test of quality control in hospitals. (authors)

  2. Comparison of air-kerma strength determinations for HDR 192Ir sources

    International Nuclear Information System (INIS)

    Purpose: To perform a comparison of the interim air-kerma strength standard for high dose rate (HDR) 192Ir brachytherapy sources maintained by University of Wisconsin Accredited Dosimetry Calibration Laboratory (UWADCL) with measurements of the various source models using modified techniques from the literature. The current interim standard was established by Goetsch et al. in 1991 and has remained unchanged to date. Methods: The improved, laser-aligned seven-distance apparatus of University of Wisconsin Medical Radiation Research Center (UWMRRC) was used to perform air-kerma strength measurements of five different HDR 192Ir source models. The results of these measurements were compared with those from well chambers traceable to the original standard. Alternative methodologies for interpolating the 192Ir air-kerma calibration coefficient from the NIST air-kerma standards at 137Cs and 250 kVp x rays (M250) were investigated and intercompared. As part of the interpolation method comparison, the Monte Carlo code EGSnrc was used to calculate updated values of Awall for the Exradin A3 chamber used for air-kerma strength measurements. The effects of air attenuation and scatter, room scatter, as well as the solution method were investigated in detail. Results: The average measurements when using the inverse NK interpolation method for the Classic Nucletron, Nucletron microSelectron, VariSource VS2000, GammaMed Plus, and Flexisource were found to be 0.47%, -0.10%, -1.13%, -0.20%, and 0.89% different than the existing standard, respectively. A further investigation of the differences observed between the sources was performed using MCNP5 Monte Carlo simulations of each source model inside a full model of an HDR 1000 Plus well chamber. Conclusions: Although the differences between the source models were found to be statistically significant, the equally weighted average difference between the seven-distance measurements and the well chambers was 0.01%, confirming that it is

  3. Calculated neutron air kerma strength conversion factors for a generically encapsulated Cf-252 brachytherapy source

    CERN Document Server

    Rivard, M J; D'Errico, F; Tsai, J S; Ulin, K; Engler, M J

    2002-01-01

    The sup 2 sup 5 sup 2 Cf neutron air kerma strength conversion factor (S sub K sub N /m sub C sub f) is a parameter needed to convert the radionuclide mass (mu g) provided by Oak Ridge National Laboratory into neutron air kerma strength required by modern clinical brachytherapy dosimetry formalisms indicated by Task Group No. 43 of the American Association of Physicists in Medicine (AAPM). The impact of currently used or proposed encapsulating materials for sup 2 sup 5 sup 2 Cf brachytherapy sources (Pt/Ir-10%, 316L stainless steel, nitinol, and Zircaloy-2) on S sub K sub N /m sub C sub f was calculated and results were fit to linear equations. Only for substantial encapsulation thicknesses, did S sub K sub N /m sub C sub f decrease, while the impact of source encapsulation composition is increasingly negligible as Z increases. These findings are explained on the basis of the non-relativistic kinematics governing the majority of sup 2 sup 5 sup 2 Cf neutron interactions. Neutron kerma and energy spectra resul...

  4. Air kerma strength calibration of 0.6 cc Farmer chamber for 192Ir HDR source

    International Nuclear Information System (INIS)

    One of the methods adopted by hospitals for the calibration of the HDR 192Ir source, in terms of Air Kerma Strength (AKS) is to use 0.6cc chamber at short source to chamber distances for measuring the air kerma rate at the chamber position and then compute the AKS using the appropriate correction factors. However, the 0.6 cc Farmer type chambers purchased by the users for the calibration of the HDR 192Ir source, are not generally provided with an HDR 192Ir calibration factor. With the result, many hospitals that have purchased the Farmer type chamber for the calibration of 192Ir HDR sources, use the 60Co calibration factor for this purpose. The use of 60Co calibration factor for the 192Ir HDR source would unnecessarily increase the uncertainty of the measured AKS. Again, because of the low chamber sensitivity, hospitals often use, source to chamber distances as small as a few cm for calibrating the 192Ir HDR source. In the absence of a rigid source-chamber positioning system, this can lead to several percent errors in AKS determination. Also, hospitals often don't take into account corrections for the room scatter or the fluence non-uniformity across the chamber, which further increase the uncertainty of the measured AKS

  5. Air-kerma strength determination of a new directional {sup 103}Pd source

    Energy Technology Data Exchange (ETDEWEB)

    Aima, Manik, E-mail: aima@wisc.edu; Reed, Joshua L.; DeWerd, Larry A.; Culberson, Wesley S. [Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

    2015-12-15

    Purpose: A new directional {sup 103}Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing {sup 103}Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active {sup 103}Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S{sub K}) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S{sub K} to a well-type ionization chamber. Methods: S{sub K} measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S{sub K} from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S{sub K} with the presence of gold fluorescent energy lines. In addition to S{sub K} measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S{sub K} values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the S

  6. Air-kerma strength determination of a new directional 103Pd source

    International Nuclear Information System (INIS)

    Purpose: A new directional 103Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing 103Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active 103Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber. Methods: SK measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity SK from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine SK with the presence of gold fluorescent energy lines. In addition to SK measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating SK values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the SK of four CivaDots with reproducibilities within 0.3%. Monte

  7. Recent developments and current status of air kerma standards

    International Nuclear Information System (INIS)

    Primary Standard Dosimetry Laboratories (PSDL) usually maintain air kerma standards for kilovoltage x-rays (10 kV to 300 kV) and for 137Cs- and 60Co-γ radiation. Free-air ionisation chambers (FAC) and cavity ionisation chambers are used as primary air kerma standards for kilovoltage x-rays and for 137Cs- and 60Co-γ radiation, respectively. The majority of the National Metrology Institutes (NMIs) signed the Mutual Recognition Arrangement (MRA) of national measurement standards and of calibration and measurement certificates issued by NMIs. The MRA has been available for signature since 14th October 1999. According to the MRA, the signatories participate in CIPM key comparisons executed by the Consultative Committees or the BIPM, leading to a key comparison reference value. The degree of equivalence of a national measurement standard is expressed quantitatively in terms of its deviation from the key comparison reference value and the uncertainty of this deviation. For air kerma standards the Consultative Committee for Ionising Radiation (CCRI(I)) currently maintains three types of key comparisons and a so-called supplementary comparison. The air kerma key comparisons are organised bilaterally and are carried out between the air kerma standards of the BIPM and the participating NMIs. The radiations used are low-energy (10 kV to 50 kV) and medium energy (100 kV to 250 kV) x-ray beams and 137Cs- and 60Co-γ radiation. To be entitled to enter the key comparison database with respect to air kerma an NMI has to participate in a key comparison within a time period of 10 years. In keeping with the longstanding method of presenting the data, the CCRI(I) took the decision at its meeting in 1999 to use the BIPM determination of air kerma rate as the key comparison reference value. For this reason the BIPM air kerma standards are of special importance. Due to the fact that the air kerma key comparisons have been conducted on an ongoing basis since 1966 for low-energy x

  8. Kerma determination in air on mamma by thermoluminescence; Determinacion de Kerma en aire en mama por termoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Palacios P, L. L.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico)], e-mail: lpalaciop@ipn.mx

    2009-10-15

    In this work the experimental results of the entrance exposition are shown and Kerma in air [mGy] in mamma obtained by irradiation of accreditation phantom of American College of Radiology (ACR). The irradiations were realized in a conventional mammography equipment of Hospital Juarez in Mexico; the technique used during the irradiations was of automatic exposition; the thickness for the phantom ACR obtained by the technique were of 4.2 and 4.5 cm; the kilo voltage pick was of 24 kV{sub p}, the time and the milli amperage per second variable. The measuring of Kerma in air was obtained with thermoluminescent dosemeters of solid state, of nano particles of zirconium dioxide prepared by the precipitation method. The dosemeters were homogenized previously in low energies of X-rays that are those used for mammography. The thermoluminescent dosemeters of ZrO{sub 2} were calibrated by means of an ionization chamber for different expositions. The calibration curve is reported for the exposition and Kerma in air against thermoluminescent intensity obtained by reading of thermoluminescent dosemeters of ZrO{sub 2}, as well as the technique employee for the Kerma determination in air and entrance exposition in mamma. (Author)

  9. Evaluation of entrance surface air kerma in pediatric chest radiography

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior–posterior (AP) and posterior–anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0–1 y, 1–5 y, 5–10 y, and 10–15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels. - Highlights: • The entrance surface air kerma of chest X-ray examinations in pediatric patients was estimated. • The data were analyzed for patients aged up to 15 y, stratified by age. • The doses of LAT examinations were 40% higher than of AP/PA because of kV used. • An increase in kV with a decrease in mAs leads to significant dose reduction

  10. Air kerma rates measurement in an interventional cardiology suite

    International Nuclear Information System (INIS)

    In Interventional Cardiology (IC), the assessment of the radiation that the physicians are exposed to is extremely important because the irradiation is not uniform and the received doses are substantially high. During the procedure, the radiation control is complex and there are several reasons for the high exposure levels. It is necessary to perform dosimetric assessments in different parts of the physicians' body and in different specific points of the examination room. By analyzing this information it is possible to determine the probable causes and to provide recommendations, aiming at optimizing the radiological protection. This work had the following objectives: to assess the exposition levels at representative points of critical anatomical regions of the physicians' body who perform IC examinations; to provide means to implement personal monitoring procedures; and to make them aware of the radiation risks. Measurements of air kerma rates were performed in 45 points around the examination table, along the room. Such measurements were made in the conditions frequently used in coronary angiography and coronary angioplasties procedures: adult patient phantom; RAO, LAO and AP incidences; fluoro and digital modes; 13cm and 17cm magnification modes; frequencies of 30f/s (fluoro) and 15 f/s (digital); typical field size used during examinations. Data were obtained at the lenses, chest, hands, gonads and knees levels. For AP incidence, the lowest contributions for scattered radiation and a more homogeneous distribution of radiation were observed. The highest air kerma rates were obtained during digital acquisition mode and for LAO incidence on interventional radiologists, anaesthesists and nurses. The most critical anatomical regions were the knees and gonads. Air kerma rates of about 7,8mGy/h were registered in some places. At physicians' hands position, rates of about 5mGy/h were reached. In several points and levels measured (workload ∼ 6 examinations/day), this

  11. Status of air kerma and absorbed dose standards in India

    International Nuclear Information System (INIS)

    Full text: The Radiation Safety Systems Division of Bhabha Atomic Research Centre, India maintains Primary and Secondary Standards of various parameters of radiation measurements and provides calibration services to various users of radiation in the country. This is an apex laboratory in India and plays a pivotal role in ensuring accurate radiological measurements. The laboratory coordinates national intercomparisons of radiation measurements to maintain their uniformity and traceability and is linked through various programmes with the other International organizations such as Bureau Internationale des Poids et Mesures (BIPM) Paris, International Atomic Energy Agency (IAEA) Vienna, Asia Pacific Metrology Programme (APMP) Taiwan. It is the recognized Regional Secondary Standards Dosimetry Laboratory (SSDL) of IAEA/WHO (World Health Organisation). This paper brings out the status of various primary and secondary standards for radiological measurements maintained at BARC. 1. Primary Exposure/Air-kerma standard at Co-60 energy (therapy level): The primary standard for exposure/ air-kerma measurements maintained at BARC is a graphite cavity chamber of volume 4.362 cc with an internal diameter of 1.8 cm, internal height of 1.78 cm and wall thickness of 704.3mg/cm2. Correction factors for the difference between electron stopping powers, photon mass energy absorption coefficients of air and graphite wall, correction for recombination, radiation field non-uniformity, stem scatter and polarity effect are applied and the maximum overall uncertainty in the realisation of exposure/air-kerma is around ±1%. This standard has been intercompared with IAEA and BIPM through transfer standard and the agreement in the results are better than ±1%. An intercomparison under the APMP programme is to be held during May, 2002. 2. Primary Exposure/Air-kerma standard at protection and brachytherapy level: A set of three spherical graphite-walled cavity chambers of different air-volumes are

  12. The air-kerma rate constant of 192Ir.

    Science.gov (United States)

    Ninković, M M; Raiĉevìć, J J

    1993-01-01

    The air-kerma rate constant gamma delta (and its precursors), as one of the basic radiation characteristics of 192Ir, was determined by many authors. Analysis of accessible data on this quantity led us to the conclusion that published data strongly disagree. That is the reason we calculated this quantity on the basis of our and many other authors' gamma-ray spectral data and the latest data for mass energy-transfer coefficients for air. In this way, a value was obtained for gamma delta of 30.0 +/- 0.9 a Gy m2 s-1 Bq-1 for an unshielded 192Ir source and 27.8 +/- 0.9 a Gy m2s -1Bq-1 for a standard packaged radioactive source taking into account attenuation of gamma rays in the platinum source wall. PMID:8416220

  13. Comparison of the NIST and ENEA air kerma standards

    International Nuclear Information System (INIS)

    A comparison was made between the National Institute of Standards and Technology (NIST) and Ente per le Nuov Tecnologie l'Energia e l'Ambiente (ENEA) air kerma standards for medium energy x rays and 60Co gamma rays. The comparison took place at ENEA in June 1994. Two different transfer chambers from NIST were used for the comparison. The measurements were made at radiation qualities similar to those used at the Bureau International des Poids et Mesures (BIPM) (generating voltages of 100 kV, 135 kV, 180 kV and 250 kV, respectively) and with 60Co gamma radiation. The transfer chamber calibration factors obtained at the NIST and at the ENEA agreed with one another to 0.03% for 60Co gamma radiation and between 0.1% to 0.8% for the medium energy x-ray beam codes

  14. X-rays spectrum and air Kerma during a mammography study; Espectro de los rayos X y Kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)], e-mail: fermineutron@yahoo.com

    2009-10-15

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +{sub -} 0.03 m G, while the other obtained by the calculations was of 0.96 +{sub -} 0.06 mGy, to compare both do not exist significant differences. (author)

  15. Evaluation of entrance surface air kerma from exposure index in computed radiography

    Science.gov (United States)

    Costa, A. M.; Pelegrino, M. S.

    2014-11-01

    The aim of this study was to establish an indirect method to calculate the values of entrance surface air kerma in patients undergoing diagnostic examinations in X-ray systems with computed radiography based on the exposure index. The entrance surface air kerma values were compared with values obtained also indirectly based on measurements of X-ray tube output. The mean±standard deviation (1σ) and third quartile for entrance surface air kerma calculated from the exposure index were 2.1±1.0 mGy and 3.0 mGy, respectively. For entrance surface air kerma based on measurements of the X-ray tube output, the mean±standard deviation (1σ) and third quartile were respectively 3.1±1.9 mGy and 5.5 mGy. The observed values of entrance surface air kerma are smaller than the reference level adopted in Brazil (10 mGy). The results obtained with both methods were similar when taking into account the estimated uncertainties in the determination of air kerma values, although the reproducibility of the determinations based on the exposure index is better.

  16. Standardization of iridium-192 coiled source in terms of air kerma output

    International Nuclear Information System (INIS)

    ICRU (1985) recommended that the output of gamma ray brachytherapy sources should be specified in terms of reference air kerma rate, defined as the kerma rate to air in air at a reference distance of 1 meter, perpendicular to the long axis of the source, corrected for air attenuation and scattering. As these measurements are difficult to carry out in the routine clinical use, it is the common practice to calibrate the re-entrant ionization chamber with respect to open air measurements and use the re-entrant chamber for routine measurements. This paper reports on the measurements carried out to correlate the nominal activity and air kerma rate of 192Ir wire sources supplied by the Board of Radiation and Isotope Technology, Department of Atomic Energy. (author). 3 refs, 1 tab

  17. Reference air kerma and kerma-area product as estimators of peak skin dose for fluoroscopically guided interventions

    International Nuclear Information System (INIS)

    Purpose: To determine more accurate regression formulas for estimating peak skin dose (PSD) from reference air kerma (RAK) or kerma-area product (KAP). Methods: After grouping of the data from 21 procedures into 13 clinically similar groups, assessments were made of optimal clustering using the Bayesian information criterion to obtain the optimal linear regressions of (log-transformed) PSD vs RAK, PSD vs KAP, and PSD vs RAK and KAP. Results: Three clusters of clinical groups were optimal in regression of PSD vs RAK, seven clusters of clinical groups were optimal in regression of PSD vs KAP, and six clusters of clinical groups were optimal in regression of PSD vs RAK and KAP. Prediction of PSD using both RAK and KAP is significantly better than prediction of PSD with either RAK or KAP alone. The regression of PSD vs RAK provided better predictions of PSD than the regression of PSD vs KAP. The partial-pooling (clustered) method yields smaller mean squared errors compared with the complete-pooling method.Conclusion: PSD distributions for interventional radiology procedures are log-normal. Estimates of PSD derived from RAK and KAP jointly are most accurate, followed closely by estimates derived from RAK alone. Estimates of PSD derived from KAP alone are the least accurate. Using a stochastic search approach, it is possible to cluster together certain dissimilar types of procedures to minimize the total error sum of squares.

  18. X-rays spectrum and air Kerma during a mammography study

    International Nuclear Information System (INIS)

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO2+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the other obtained by the calculations was of 0.96 +- 0.06 mGy, to compare both do not exist significant differences. (author)

  19. X-Rays spectrum and air kerma during a mammography study;Espectro de los rayos X y kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur No. 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Chacon R, A.; Vega C, H. R., E-mail: ramirezgonzalezjaime@yahoo.com.m [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2009-10-15

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the obtained by means of the calculations was of 0.96 +- 0.06 mGy, when comparing both significant differences do not exist. (Author)

  20. A comparison of measured and calculated values of air kerma rates from 137Cs in soil

    Directory of Open Access Journals (Sweden)

    V. P. Ramzaev

    2016-01-01

    Full Text Available In 2010, a study was conducted to determine the air gamma dose rate from 137Cs deposited in soil. The gamma dose rate measurements and soil sampling were performed at 30 reference plots from the south-west districts of the Bryansk region (Russia that had been heavily contaminated as a result of the Chernobyl accident. The 137Cs inventory in the top 20 cm of soil ranged from 260 kBq m–2 to 2800 kBq m–2. Vertical distributions of 137Cs in soil cores (6 samples per a plot were determined after their sectioning into ten horizontal layers of 2 cm thickness. The vertical distributions of 137Cs in soil were employed to calculate air kerma rates, K, using two independent methods proposed by Saito and Jacob [Radiat. Prot. Dosimetry, 1995, Vol. 58, P. 29–45] and Golikov et al. [Contaminated Forests– Recent Developments in Risk Identification and Future Perspective. Kluwer Academic Publishers, 1999. – P. 333–341]. A very good coincidence between the methods was observed (Spearman’s rank coefficient of correlation = 0.952; P<0.01; on average, a difference between the kerma rates calculated with two methods did not exceed 3%. The calculated air kerma rates agreed with the measured dose rates in air very well (Spearman’s coefficient of correlation = 0.952; P<0.01. For large grassland plots (n=19, the measured dose rates were on average 6% less than the calculated kerma rates. The tested methods for calculating the air dose rate from 137Cs in soil can be recommended for practical studies in radiology and radioecology. 

  1. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray

    International Nuclear Information System (INIS)

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm2, for patients with 1 to 5 years old range from 17 to 192 mGy.cm2, and from 30,4 to 136,2 mGy.cm2 for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  2. Measurement of air kerma rate and absorbed dose for brachytherapy sources with secondary standard dosimeter

    International Nuclear Information System (INIS)

    The air kerma measurements for brachytherapy sources are generally recommended to be done at one meter using large volume chambers. These measurements pose problems due to low signal from brachytherapy sources. Non-availability of calibrated large volume chambers at a hospital adds to the problem of air kerma measurements. Therefore, the use of commonly available secondary standard dosimeter having 0.6 cc chambers has been examined. Correction factors to be applied at small source to chamber distances have been determined. Measurements from 137Cs source of nominal activity as low as 1.11 GBq (30 mCi) could be carried out using an integration time of about 20 minutes at minimum distance of 1.5 cm. For source to chamber distance beyond 5 cm, the correction factor approaches unity. (author)

  3. Portable meter study of ionizing radiation Teletector in high rates of air kerma

    International Nuclear Information System (INIS)

    A set of portable meters of ionizing radiation high rates of air kerma (teletectors) commonly used in emergencies in Brazil and sent to the Calibration Laboratory of IPEN were under several tests and analyst is parameters for the detectors behavior were established. Applied tests were: energy dependence and primarily overload with the new irradiation system. Thus it was possible to determine the most common characteristic found in these equipment (quality control programs) and new calibration criteria were established following international recommendations. (author)

  4. Air kerma distribution in an irradiation facility - Comparison of Monte Carlo simulations with physical dosimetry

    International Nuclear Information System (INIS)

    In order to evaluate the effectiveness of Monte Carlo methods applied to shielding calculations, an air kerma rate evaluation was performed in different locations of a 60Co gamma irradiator, operated for industrial and research purposes in a state laboratory at Nuclear and Technological Inst. near Lisbon. The MCNPX code was used to perform the radiation transport simulation along the facility. Variance reduction techniques were used by implementing, among others, the weight window generator to account for the air kerma rate in the access maze leading to the facility's irradiation chamber. Analog Monte Carlo simulations were also performed to test the correct implementation of the non analog techniques used and to evaluate the computational efficiency gain. The validation of the computational results is discussed by comparison with physical dosimetry measurements using ionization chambers. The results obtained show a good agreement between the simulations and the measurements for the positions in and the exit of the irradiation room. Discrepancies were found for the positions where the air kerma rate is lower resulting from the deeper penetration of radiation across the shields and scattering through the maze walls. Further insight must be gained to improve the results at these positions. (authors)

  5. Comparison of two different methods to determine the air kerma calibration factor (NK) for 192Ir

    International Nuclear Information System (INIS)

    In brachytherapy, encapsulated radioactive Low Dose Rate (LDR) and High Dose Rate (HDR) sources are used to deliver a dose to tissue near the source. One of the nuclides used in LDR as well as in HDR brachytherapy sources is 192Ir. In document IAEA-TECDOC-1079, Calibration of Brachytherapy Sources, recommendations on standardized procedures for the calibration of brachytherapy sources at SSDLs and hospitals are given. One of these recommendations is the use of an ionisation chamber with an air-kerma calibration factor for 192lr sources. The problem to derive a calibration factor for 192Ir is that the most important part of the spectrum of an 192lr brachytherapy source falls in an energy gap between the standards for x-rays and the standards for gamma-rays established at primary laboratories. It is therefore unavoidable to obtain the air kerma calibration for the ionisation chamber using an indirect method. The method recommended by IAEA for the determination of the air-kerma calibration factors is based on a technique developed by Goetsch et al. In the Netherlands a different method is recommended. This method is based on a weighting procedure of the 192Ir energy spectrum over the response curve of an ionisation chamber and differs with the procedure recommended by IAEA for a NE2561 ionisation chamber by about 0.9 %

  6. X-Rays spectrum and air kerma during a mammography study

    International Nuclear Information System (INIS)

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO2+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 ± 0.03 m G, while the obtained by means of the calculations was of 0.96 ± 0.06 mGy, when comparing both significant differences do not exist. (Author)

  7. Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures

    Science.gov (United States)

    Vijayan, Sarath; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

    2016-03-01

    The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

  8. Sensitivity/uncertainty analysis for free-in-air tissue kerma due to initial radiation at Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Uncertainty estimates and cross correlations by range/survivor have been calculated for the Hiroshima and Nagasaki free-in-air (FIA) tissue kerma obtained from two-dimensional air/ground transport calculations. The uncertainties due to modeling parameter and basic nuclear transport data uncertainties were calculated for 700-, 1000-, and 1500-m ground ranges. Only the FIA tissue kerma due to initial radiation was treated in the analysis; the uncertainties associated with terrain and building shielding and phantom attenuation were not considered in this study. Uncertainties of --20% were obtained for the prompt neutron and secondary gamma kerma and 30% for the prompt gamma kerma at both cities. The uncertainties on the total prompt kerma at Hiroshima and Nagasaki are --18 and 15%, respectively. The estimated uncertainties vary only slightly by ground range and are fairly highly correlated. The total prompt kerma uncertainties are dominated by the secondary gamma uncertainties, which in turn are dominated by the modeling parameter uncertainties, particularly those associated with the weapon yield and radiation sources

  9. Image quality and volume computed tomography air kerma index (Cvol) evaluation in Recife

    International Nuclear Information System (INIS)

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (CVOL) and air kerma length product (PKL,CT) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms (nCW), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the CVOL values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the PKL,CT, from 150 to 750 mGy·cm. The CVOL values for routine chest procedures varied from 3 to 26 mGy and the PKL,CT, between 120 and 460 mGy·cm. In relation to Hi-resolution chest exams, CVOL values were from 1.0 to 2.7 mGy and the PKL,CT values varied between 24 and 67 mGy·cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the ACR requirements, suggesting the need to implement quality assurance programs at the

  10. Product kerma in the air-area and radiation dose in dental radiodiagnosis

    International Nuclear Information System (INIS)

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  11. Measurement of air kerma rate for Cs-137 using different ionization chambers

    International Nuclear Information System (INIS)

    Due to the importance of radiation doses in medical field quality assurance should be established in order to maintain a reasonable balance between the purpose of application and exposure. This study had been carried out to achieve quality control for protection based on air kerma rate. Measurements were performed by using Cs-137 for the comparison of two working ionization chambers in secondary standard dosimetry laboratory of Sudan. Spherical ionization chamber L S-01 1000 cc S/N 912 and Farmer ionization chamber 2675 A 600 cc S/N 0511, respectively. The results obtained from this study have been represented as mean and their standard deviations shown in most cases remains at 5% uncertainly. Comparison between kinetic energy released per unit mass in air rate (air kerma rate) were obtained by using spherical ionization chamber L S-01 1000 cc S/N 912 and results have been determined using inverse square law. The differences have been represented as means and standard deviations with significant P-value less than 0.05. Spherical ionization chamber gives accurate, reproducible results with acceptable uncertainty which is more suitable for calibration of radiation detectors.(Author)

  12. Product kerma in the air-area and radiation dose in dental radiodiagnosis; Produto kerma ar-area e dose efetiva em radiodiagnostico odontologico

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alessandro Martins da, E-mail: amcosta@usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica

    2014-07-01

    The main purpose of patient dosimetry in diagnostic radiology is to determine dosimetric quantities for the establishment and use of reference levels and comparative risk assessment. In recent publications the use of the air kerma-area product, PKA, has been suggested in dental radiology, as this quantity is more closely related to risk. The aim of this study was to perform a preliminary survey of PKA and effective dose in different types of dental examinations. The future perspective is a large-scale survey for the establishment and use of diagnostic reference levels in dentistry in Brazil. (author)

  13. Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements

    International Nuclear Information System (INIS)

    Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere DPMMA(10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/Ka obtaining a value of 1.20 Sv Gy-1 with a uc= 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy-1 with a uc= 2%. (Author)

  14. Kerma rate evaluation in the air in a room interventional cardiology

    International Nuclear Information System (INIS)

    In recent years, the number of interventional cardiology procedures is increasing. However, due to the long time of fluoroscopy in these procedures, care teams can receive high doses of radiation. The radiation scattered by the patient is not uniform, and their assessment is of utmost importance. This study aimed to estimate and map the kerma rate in the air at the time of the gonads, in an interventional cardiology room, seeking to optimize the dose absorbed by individuals occupationally exposed to ionizing radiation. For data collection, the room was divided into quadrants of 1m2, totaling 40 collection points. The simulator was positioned so that its entry surface was located in the interventional reference point. Were chosen the conditions that simulate angiography and angioplasty procedures performed in the service. The data were obtained for height of 1 meter, gonad region. The results obtained for kerma rates in air, in quadrants, show that higher measured values was in the vicinity of the X-ray tube. Has been found that the medical staff are more exposed, because of its location during the procedure, around the table. The law of the inverse square distance of the farthest points of the X-ray tube were verified

  15. Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities

    International Nuclear Information System (INIS)

    In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for 192Ir and 60Co HDR applications to account for several different bunker layouts. For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emitted by 192Ir and 60Co will reduce the lead thickness by a factor of five for 192Ir and ten for 60Co. This will significantly lighten the door and hence simplify construction and operating requirements for all bunkers. The adaptation proposed in this study to estimate the air-kerma rate at the door depends on the complexity of the maze: it provides good results for bunkers with a maze (i.e. similar to those used for linacs for which the NCRP 151 methodology was developed) but fails for less conventional designs. For those facilities, a specific Monte Carlo study is in order for reasons of safety and cost-effectiveness. (paper)

  16. A new approach to the determination of air kerma using primary-standard cavity ionization chambers

    International Nuclear Information System (INIS)

    A consistent formalism is presented using Monte Carlo calculations to determine the reference air kerma from the measured energy deposition in a primary-standard cavity ionization chamber. A global approach avoiding the use of cavity ionization theory is discussed and its limitations shown in relation to the use of the recommended value for W. The role of charged-particle equilibrium is outlined and the consequent requirements placed on the calculations are detailed. Values for correction factors are presented for the BIPM air-kerma standard for 60Co, making use of the Monte Carlo code PENELOPE, a detailed geometrical model of the BIPM 60Co source and event-by-event electron transport. While the wall correction factor kwall = 1.0012(2) is somewhat lower than the existing value, the axial non-uniformity correction kan = 1.0027(3) is significantly higher. The use of a point source in the evaluation of kan is discussed. A comparison is made of the calculated dose ratio with the Bragg-Gray and Spencer-Attix stopping-power ratios, the results indicating a preference for the Bragg-Gray approach in this particular case. A change to the recommended value for W of up to 2 parts in 103 is discussed. The uncertainties arising from the geometrical models, the use of phase-space files, the radiation transport algorithms and the underlying radiation interaction coefficients are estimated

  17. From Reference Air Kerma Rate to Nominal Absorbed Dose Rate to Water: Paradigm Shift in Photon Brachytherapy

    International Nuclear Information System (INIS)

    In brachytherapy (BT), photon radiation sources are presently calibrated in terms of the reference air kerma rate Kδ (or air kerma strength SK). By direct source calibration in terms of Dw,1, the nominal absorbed dose rate to water at the TG-43U1 reference position at 1 cm in water and with the ability to measure distributions of this quantity, the accuracy of clinical BT-dosimetry should increase due to decreased calibration uncertainties compared to present methods. Several Dw,1 primary standards are under development for high energy, high dose rate and low energy, low dose rate sources. To provide worldwide traceability and guidance for clinical medical physicists, an ISO standardization project, Clinical Dosimetry - Photon Radiation Sources Used in Brachytherapy, is considered, in continuation of ISO 21439 (2009) for beta sources. Clear terms and definitions are fundamental. Reclassification of BT-photon radiation qualities is also needed, introducing a range of medium energy photons with mean energies between 40 keV and 150 keV. Radionuclide BT-sources and electronic X ray BT-sources, BT-detectors and BT-phantoms should be characterized by sets of reference data, through which the clinical medical physicist could critically evaluate the data supplied by the manufacturer, prior to clinical application. Plastic scintillators have the potential for transfer standards of high accuracy and for verification measurements of BT-source output in phantoms. Based on and extending the AAPM TG-43U1 formalism, this planned ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainties. (author)

  18. Kerma rate evaluation in the air in a room interventional cardiology; Avaliacao da taxa de Kerma no ar em uma sala de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2014-07-01

    In recent years, the number of interventional cardiology procedures is increasing. However, due to the long time of fluoroscopy in these procedures, care teams can receive high doses of radiation. The radiation scattered by the patient is not uniform, and their assessment is of utmost importance. This study aimed to estimate and map the kerma rate in the air at the time of the gonads, in an interventional cardiology room, seeking to optimize the dose absorbed by individuals occupationally exposed to ionizing radiation. For data collection, the room was divided into quadrants of 1m{sup 2}, totaling 40 collection points. The simulator was positioned so that its entry surface was located in the interventional reference point. Were chosen the conditions that simulate angiography and angioplasty procedures performed in the service. The data were obtained for height of 1 meter, gonad region. The results obtained for kerma rates in air, in quadrants, show that higher measured values was in the vicinity of the X-ray tube. Has been found that the medical staff are more exposed, because of its location during the procedure, around the table. The law of the inverse square distance of the farthest points of the X-ray tube were verified.

  19. Rate air Kerma entrance skin of patients undergoing hemodynamic procedures in the State of Santa Catarina, Brazil

    International Nuclear Information System (INIS)

    This paper presents the results of the measured values of the skin entrance Air Kerma Rate in patients submitted to hemodynamic procedures, in the State of Santa Catarina, using as limit values set by the International Basic Safety Standards Guide, published by the International Atomic Energy Agency (IAEA ), and comparing them to the limits established by the Ordinance No. 453/1998. Tests were performed to measure the rate of Kerma skin entrance in 13 hemodynamic equipment in 10 hospitals in the state of Santa Catarina, between January 2011 and December 2012, in hemodynamic operated through fluoroscopy mode. Among the evaluated equipment, 77% disagree with the limits established in the International Basic Safety Standards, however, if compared the values of the Air Kerma rate obtained with the limit established by Ordinance No. 453, 100% of the devices are approved. The results obtained in this paper suggest the need for revision of the Ordinance No. 453/1998, by the regulatory agencies. (author)

  20. New primary ionization chambers at LNE-LNHB for determining the air kerma in a cobalt-60 beam

    International Nuclear Information System (INIS)

    For radioprotection, the reference quantity is air kerma. For an cobalt-60 beam, the reference dosimeter is a cavity ionization chamber whose volume is measured. The new LNE-LNHB reference is based on six different chambers instead of one as was done previously. Although every new ionization chamber was treated as much as possible in the same way (manufacturing, measurements of volumes, wall effect calculations, current corrections), a maximum discrepancy of 0.2% was observed between the final measurement results from each chamber. The final value of the air kerma rate in reference conditions was determined as the mean value of the measurement results from all six chambers. Among the different factors whose determination is necessary to calculate the air kerma rate, some are considered independent of or common to all the graphite-walled ionization chambers (for example, mean energy expended by an electron to produce an ion pair in dry air), while others vary for each chamber (for example, air cavity ionic collection volume). Considering that the uncertainties of the individual ionization chamber measurement results seem slightly underestimated, the uncertainty on the mean of the six chamber-dependent factors products was taken equal to the standard deviation of the sample composed of the six chamber-dependent factors products (0.08%). Compared to the previous standard, the air kerma rate of the 60Co photon beam would then increase by 0.09% and the air kerma rate uncertainty would drop from 0.38% to 0.31%. This article describes the procedure used to establish the primary standard in terms of absorbed dose to tissue of LNE-LNHB. (authors)

  1. Air kerma standardization for diagnostic radiology in a secondary standard laboratory

    International Nuclear Information System (INIS)

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Brazilian Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. The objective of this work was to implement the standardization of the air kerma for the unatenuated qualities (RQR) of IEC 61267 in the National Laboratory of Metrology of the Ionizing Radiations (LNMRI) of the Institute of Radiation Protection and Dosimetry (IRD). Technical procedures were developed together with uncertainty budget. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. (author)

  2. A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography

    International Nuclear Information System (INIS)

    In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations and does not exceed 75% for the leakage radiation

  3. Age-Dependent Dose in Organs per Unit Air Kerma Free-in-Air: Conversion Coefficients for Environmental Exposure

    International Nuclear Information System (INIS)

    Conversion coefficients from air kerma free-in-air to effective dose and dose in organs have been calculated for hermaphrodite 1, 5, 10, 15 year old children and adult anthropomorphic mathematical models. The 15 year old child phantom is also used as the adult female phantom. The irradiation geometry considered was the phantom standing on an almost infinite plane source, which is the geometry normally used for detector's calibration for environmental in situ measurements. The ADAM computer code has been modified to use the phantoms described by Cristy for the children phantoms, the adult male phantom is described in the ICRP Report 23. Thirty-six incident energies ranging from 10 keV to 10 MeV were selected for the incident radiation. (author)

  4. The ratios of effective dose to entrance skin dose to the air kerma for some medical sources

    International Nuclear Information System (INIS)

    Results are presented for the ratios of the effective dose to skin entrance dose and to air kerma for broad beams of radiation expected to be encountered by medical workers. These workers are monitored by the Personal Radiation Monitoring Service (PRMS) using thermoluminescent dosimeters worn at the front of the body to provide estimates of the entrance skin dose. Factors are given for converting estimates of entrance skin dose to effective dose as defined by the International Commission on Radiological Protection (ICRP 1991) for beams incident on the body by one of three modes-from the front of the subject, from the back of the subject or by rotation around the subject. Additional tables are also given to calculate effective dose for these beams from a measurement of air kerma free-in-air

  5. Study and determination of the national dosimetric standards in terms of air kerma for X-rays radiation fields of low and medium-energies

    International Nuclear Information System (INIS)

    Progress in radiation protection and radiotherapy, and the increased needs in terms of accuracy lead national metrology institutes to improve the standard. For ionizing radiation, the standard is defined by an absolute instrument used for air kerma rate measurement. The aim of the thesis is to establish standards, in terms of air kerma for X-rays beams of low and medium-energies. This work enables to complement the standard beam range of the Laboratoire National Henri Becquerel (LNHB). Two free-air chambers have been developed, WK06 for medium-energy and WK07 for low-energy. The air-kerma rate is corrected by several correction factors. Some are determined experimentally; and the others by using Monte Carlo simulations. The uncertainty budget of the air-kerma rate at one standard deviation has been established. These dosimetric standards were compared with those of counterparts' laboratories and are consistent in terms of degree of equivalence. (author)

  6. Transmission ionization chambers for measurements of air collision kerma integrated over beam area. Factors limiting the accuracy of calibration

    International Nuclear Information System (INIS)

    Kerma-area product meters (KAP meters) are frequently used in diagnostic radiology to measure the integral of air-collision kerma over an area A(∫A Kc,air dA) perpendicular to the x-ray beam. In this work, a precise method for calibrating a KAP meter to measure ∫A Kc,air dA is described and calibration factors determined for a broad range of tube potentials (40-200kV). The integral is determined using a large number of TL dosimeters spread over and outside the nominal field area defined as the area within 50% of maximum Kc,air. The method is compared to a simplified calibration method which approximates the integral by multiplying the kerma in the centre of the field by the nominal field area Anom. While the calibration factor using the precise method is independent of field area and distance from the source, that using the simplified method depends on both. This can be accounted for by field inhomogeneities caused by the heel effect, extrafocal radiation and scattered radiation from the KAP meter. The deviations between the calibration factors were as large as ±15% for collimator apertures of 5-100cm2 and distances from the source of 50 - 160 cm. The uncertainty in the calibration factor using the precise method was carefully evaluated and the expanded relative uncertainty estimated to be ±3% with a confidence level of 95%. (author)

  7. Comparison of the standards of air kerma of the OMH and the BIPM for 60Co gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison between the standards for air kerma of the Orszagos Meresugyi Hivatal (OMH) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in the 60Co radiation beams of the BIPM. The result, expressed as a ratio of the OMH and the BIPM standards for air kerma, indicates a relative difference of 10.9 x 10-3 with a combined standard uncertainty of 2.2 x 10-3. This new result agrees at the level of 0.4 x 10-3 with the earlier direct comparisons performed in 1986 and 1994, as modified in 2001 by the application of wall and axial non-uniformity correction factors, calculated for the OMH standards using the Monte Carlo method. (authors)

  8. Product estimate of air kerma-area and the air kerma in the input surface of the skin of pediatric patients undergoing chest X-ray; Estimativa do produto kerma ar-area e do kerma ar na superficie de entrada da pele de pacientes pediatricos submetidos a radiografia de torax

    Energy Technology Data Exchange (ETDEWEB)

    Villa-Chan, Beatriz; Carvalho, Aline; Andrade, Marcos Ely A.; Barros, Vinicius S.M. de; Khoury, Helen J., E-mail: beatrizvillachan@gmail.com, E-mail: alinecx90@gmail.com, E-mail: marcos.ely@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2014-07-01

    The aim of this paper is to evaluate the entrance air kerma (Ka,e) and the product air kerma-area (Pka) for chest examinations performed with pediatric patients in a large public hospital of Recife. For this study 89 examinations of patient with ages from zero to 10 years old were evaluated. The results showed that the mean Ka,e values, for patients of 0-1 years old, 1-5 years old and 5-10 years old, were, respectively, 100 mGy, 120 mGy and 100 mGy. The Pka values for newborn patients range from 11,9 to 58,4 mGy.cm{sup 2}, for patients with 1 to 5 years old range from 17 to 192 mGy.cm{sup 2}, and from 30,4 to 136,2 mGy.cm{sup 2} for patients with ages from 5 to 10 years old. The differences in the Pka values are due the different dimensions of the radiation field. For the results its possible to conclude that the Pka values are high, in special for patients with ages from 1 to 5 years old, indicating that the collimation of the radiation field is not adequate. (author)

  9. Entrance surface air kerma in x-ray systems for paediatric interventional cardiology: a national survey

    International Nuclear Information System (INIS)

    The aims of this work were to report the results of a national survey on entrance surface air kerma (ESAK) values for different phantom thicknesses and operation modes in paediatric interventional cardiology (IC) systems and to compare them with previous values. The national survey also offers suggested investigation levels (ILs) for ESAK in paediatric cardiac procedures. ESAK was measured on phantoms of 4-16 cm thickness of polymethyl methacrylate slabs. For low fluoroscopy mode (FM), ESAK rates ranged from 0.11 to 33.1 mGy min-1 and for high FM from 0.34 to 61.0 mGy min-1. For cine mode, values of ESAK per frame were from 1.9 to 78.2 μGy fr-1. The ILs were suggested as the third quartile of the values measured. This research showed lower ESAK values than in previous research, particularly for ESAK values in cine modes. This work represents a first step towards launching a national programme in paediatric dosimetry for IC procedures. (authors)

  10. Evaluation of the entrance surface air kerma in mammographic examinations in Rio de Janeiro (Brazil)

    International Nuclear Information System (INIS)

    The aim of this work was to evaluate the distribution of the entrance surface air kerma (ESAK) and the average glandular dose (DG) in four mammography facilities located in the city of Rio de Janeiro. The ESAK values were estimated from the X-ray tube output rate (mGy/mAs) parameters. The image quality was evaluated by the radiologists in each clinic. The ESAK values obtained for a breast thickness of 45 mm were 5.58 mGy in Clinic A, 10.07 mGy in Clinic B, 13.89 mGy in Clinic C and 7.21 mGy in Clinic D. For DG, it can be seen that, for the same compressed breast thickness (50 mm), the value varied from 0.20 to 3.60 mGy, with a mean value of 1.50 mGy for all the clinics. In image quality evaluation, Clinic D was the only one that presented a very low acceptability for quality criteria and inadequacies in relation to specks, masses and optical density. (authors)

  11. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy

    International Nuclear Information System (INIS)

    This work aims to estimate the average conversion factor of Kerma in air to H * (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm2, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  12. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories

    International Nuclear Information System (INIS)

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  13. Comparison of the standards for air kerma of the NMIJ and the BIPM for 60Co γ rays

    International Nuclear Information System (INIS)

    A first comparison of the standards for air kerma of the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and of the Bureau International des Poids et Mesures (BIPM) has been carried out in 60Co radiation. It shows that the NMIJ and BIPM standards differ by 0.72 % with a relative standard uncertainty of 2.4 x 10-3. (authors)

  14. Air kerma standardization for diagnostic radiology, and requirements proposal for calibration laboratories; Padronizacao da grandeza Kerma no ar para radiodiagnostico e proposta de requisitos para laboratorios de calibracao

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Manoel Mattos Oliveira

    2009-07-01

    The demand for calibration services and quality control in diagnostic radiology has grown in the country since the publication of the governmental regulation 453, issued by the Ministry of Health in 1998. At that time, to produce results facing the new legislation, many laboratories used different standards and radiation qualities, some of which could be inadequate. The international standards neither supplied consistent radiation qualities and standardization for the different types of equipment available. This situation changed with the publication of the new edition of the IEC 61267 standard, published in 2005. A metrology network was created, but it is not yet accredited by the accreditation organism of the country, INMETRO. The objective of this work was to implement the standardization of the air kerma for the un attenuated qualities (RQR) of IEC 61267, and to develop a requirement proposal for instruments calibration laboratories. Results of interlaboratory comparisons demonstrate that the quantity is standardized and internationally traceable. A laboratory requirement proposal was finalized and it shall be submitted to INMETRO to be used as auxiliary normative document in laboratory accreditation. (author)

  15. Conversion of Airborne Gamma ray Spectra to Ground Level Air Kerma Rates

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    A new method for relating airborne gamma-ray spectra to dose rates and kerma rates at ground level is presented. Dependent on flying altitude 50 m to 125 m the method gives correct results for gamma energies above 250 keV respective 350 keV. At lower energies the method underestimate the dose or ...

  16. Study and determination of the national dosimetric standards in terms of air kerma for X-rays radiation fields of low and medium-energies; Etude et realisation des references dosimetriques nationales en termes de kerma dans l'air pour les faisceaux de rayons X de basses et moyennes energies

    Energy Technology Data Exchange (ETDEWEB)

    Ksouri, W

    2008-12-15

    Progress in radiation protection and radiotherapy, and the increased needs in terms of accuracy lead national metrology institutes to improve the standard. For ionizing radiation, the standard is defined by an absolute instrument used for air kerma rate measurement. The aim of the thesis is to establish standards, in terms of air kerma for X-rays beams of low and medium-energies. This work enables to complement the standard beam range of the Laboratoire National Henri Becquerel (LNHB). Two free-air chambers have been developed, WK06 for medium-energy and WK07 for low-energy. The air-kerma rate is corrected by several correction factors. Some are determined experimentally; and the others by using Monte Carlo simulations. The uncertainty budget of the air-kerma rate at one standard deviation has been established. These dosimetric standards were compared with those of counterparts' laboratories and are consistent in terms of degree of equivalence. (author)

  17. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures

    International Nuclear Information System (INIS)

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences

  18. Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities

    International Nuclear Information System (INIS)

    The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, Hp(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to Hp(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037. (authors)

  19. Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.

    Science.gov (United States)

    Behrens, R

    2012-09-01

    The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037. PMID:22434922

  20. COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for 60Co γ radiation

    International Nuclear Information System (INIS)

    Results are presented of the COOMET key comparison of the national measurement standards of air kerma for 60Co γ radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. (authors)

  1. Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements; Determinacion del coeficiente de conversion para la dosis equivalente ambiental, H*(10), a partir de mediciones de kerma en aire

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez J, F. [UNAM, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Alvarez R, J. T., E-mail: trinidad.alvarez@inin.gob.mx [ININ, Departamento de Metrologia de Radiaciones Ionizantes, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere D{sub PMMA}(10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/K{sub a} obtaining a value of 1.20 Sv Gy{sup -1} with a u{sub c}= 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy{sup -1} with a u{sub c}= 2%. (Author)

  2. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133 Ba, 241 Am and 57 Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and

  3. Calculation of factors to convert from air kerma to absorbed dose to water for medium energy photons

    International Nuclear Information System (INIS)

    The IPEMB code of practice for the determination of absorbed dose for X-rays below 300 kV generating potential is a dedicated dosimetry protocol for the determination of absorbed dose based on the air kerma evaluation method for medium energy X-rays. Three separate energy ranges are dealt with in the code of practice, however, this report is only attempting to reproduce the factors in one particular range (0.5 - 4.0 nun Cu HVL) for X-rays generated at 135 and 280 kV. These X-ray qualities are used in the NPL therapy level calibration service. This new method includes the use of an air kerma calibration factor, NK, for the ionisation chamber, and the ratio of the mass-energy absorption coefficients of water to air and factors that account for the change in the response of a NE2561 ionisation chamber between calibration in air and measurement in a water phantom, kch, instead of the old F factor. This report describes the work that was undertaken to reproduce the product of the ratio of the mass-energy absorption coefficients of water to air and the kch factors. The majority of this work was carried out using Monte Carlo techniques based on the EGS4 code system. The factors calculated in this report were found to agree with values quoted in the IPEMB code of practice to within 4.2%. The quoted uncertainty for this work is 1.4% and the uncertainties for the factors quoted in the EPEMB code of practice are 3%. Hence this is reasonable agreement. Possible discrepancies in the values may be due either to limitations in the EGS4 code system, simplifications made in the chamber geometry or on the reliance on experimental data which is not quite applicable to its' use in this work. (author)

  4. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the ININ, Mexico, and the BIPM in 137Cs gamma radiation

    International Nuclear Information System (INIS)

    A direct comparison of the standards for air kerma of the Instituto Nacional de Investigaciones Nucleares (ININ), Mexico, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in February 2015. The comparison result, evaluated as a ratio of the ININ and the BIPM standards for air kerma, is 1.0048 with a combined standard uncertainty of 2.0 * 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. (authors)

  5. Conversion coefficients from air kerma to personal dose equivalent Hp(3) fir eye-lens dosimetry

    International Nuclear Information System (INIS)

    This work has been performed within the frame of the European Union ORAMED project (Optimization of Radiation protection for Medical staff). The main goal of the project is to improve standards of protection for medical staff for procedure resulting in potentially high exposures and to develop methodologies for better assessing and for reducing exposures to medical staff. The Work Package WP2 is involved in the development of practical eye lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP code of the conversion factors related to the operational quantity Hp(3). A set of energy and angular dependent conversion coefficients Hp(3)/Kair in the new proposed square cylindrical phantom of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE. The Hp(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At low photon energy, up to 1 MeV, the two sets of conversion coefficients are consistent. Nevertheless, the differences increase at higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the code MCNP published by ENEA, agree with the kerma approximation calculations with PENELOPE. They are coherent with previous calculations in phantoms different in shape. But above 1 MeV, differences between conversion coefficient values calculated with the absorbed dose and with kerma approximation are significantly increasing, especially at low incidence angles. At those energies the electron transport has to be simulated. (author)

  6. The performance of the INER improved free-air ionization chamber in the comparison of air kerma calibration coefficients for medium-energy X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.-H. E-mail: jhlee@iner.gov.tw; Kotler, L.H.; Bueermann, Ludwig; Hwang, W.-S.; Chiu, J.-H.; Wang, C.-F

    2005-01-01

    This paper describes modifications to an original design, correction factors and uncertainty evaluations for an improved free-air ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). In addition, a comparison of secondary standard air kerma calibration coefficients for 100-250 kV medium-energy X-rays was performed to verify the experimental accuracy and measurement consistency of the improved chamber. The comparison results showed a satisfactory agreement in the measurements which were within the combined expanded uncertainties (k=2)

  7. The performance of the INER improved free-air ionization chamber in the comparison of air kerma calibration coefficients for medium-energy X-rays

    International Nuclear Information System (INIS)

    This paper describes modifications to an original design, correction factors and uncertainty evaluations for an improved free-air ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). In addition, a comparison of secondary standard air kerma calibration coefficients for 100-250 kV medium-energy X-rays was performed to verify the experimental accuracy and measurement consistency of the improved chamber. The comparison results showed a satisfactory agreement in the measurements which were within the combined expanded uncertainties (k=2)

  8. COOMET regional comparison of national measurement standards of air kerma for 137Cs γ radiation at protection level

    International Nuclear Information System (INIS)

    Results are presented of the COOMET supplementary comparison of the national measurement standards for air kerma in 137Cs γ radiation at protection level (∼10 mGy/h). Ten National Metrology Institutes from the COOMET organization and the International Atomic Energy Agency participated in this COOMET project no. 445. The PTB acted as pilot laboratory. Two of the participants, the SMU (Slovakia) and the NSC-'IM' (Ukraine) participated in the measurements but did not submit a valid report of results. The comparison reference value (CRV) was obtained as the mean result of the PTB and the VNIIM, both of which had previously taken part in the key comparison BIPM-RI(I)-K5. The degree of equivalence with the CRV was evaluated. The results were consistent within the relative standard uncertainties of the comparison ranging from 0.28% to 1.3% and deviated from the CRV by less than 1%. (authors)

  9. COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for {sup 60}Co {gamma} radiation

    Energy Technology Data Exchange (ETDEWEB)

    Buermann, L. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Oborin, A.V. [D I Mendeleyev Institute for Metrology (VNIIM), St Petersburg (Russian Federation); Dobrovosky, J. [3 Slovensky Metrologicky Ustav (SMU), Bratislava (Slovakia); Milevsky, V.S. [Belarussian State Institute for Metrology (BelGIM), Minsk (Belarus); Walwyn Salas, G. [Centro de Proteccion e Higiene de las Radiaciones (CPHR), Habana (Cuba); Lapenas, A. [Radiation Metrology and Testing Centre of the Latvian National Metrology Centre Ltd (RMTC), Salaspils (Latvia)

    2009-12-15

    Results are presented of the COOMET key comparison of the national measurement standards of air kerma for {sup 60}Co {gamma} radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. (authors)

  10. Calculation of the correction factors for the primary standard of kerma in the air at the LNMRI-IRD, Rio de Janeiro, Brazil

    International Nuclear Information System (INIS)

    In order to determine the primary standardization in terms of kerma in the air, a graphite ionization chamber is used for calculation some correction factors. A program was elaborated, using the Monte Carlo Penelope for simulate the CC01-110 at the LNMRI/IRD, Rio de Janeiro, Brazil

  11. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate

    International Nuclear Information System (INIS)

    The 6- to 7-MeV high-energy gamma-ray calibration field by the 19F(p, αγ)16O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. (authors)

  12. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the VSL and the BIPM

    DEFF Research Database (Denmark)

    Alvarez, J.T.; De Pooter, J.A.; Andersen, Claus E.;

    2014-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate brachytherapy sources of the Dutch Metrology Institute (VSL), The Netherlands, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the VSL in November 2009. The comparison resu...

  13. Construction of a laboratory for the implantation of primary standardization of the magnitude kerma in the air for the X-ray beams used in mammography

    International Nuclear Information System (INIS)

    Aiming to diminish the uncertainty in each phase of the metrological chain, and the uncertainty in dosimetry processed at the X-ray beam applied in the mammography, is necessary that the LNMRI/IRD to develop a reference primary standard for the absolute form to the magnitude kerma in the air

  14. SU-E-T-552: Monte Carlo Calculation of Correction Factors for a Free-Air Ionization Chamber in Support of a National Air-Kerma Standard for Electronic Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mille, M; Bergstrom, P [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    2015-06-15

    Purpose: To use Monte Carlo radiation transport methods to calculate correction factors for a free-air ionization chamber in support of a national air-kerma standard for low-energy, miniature x-ray sources used for electronic brachytherapy (eBx). Methods: The NIST is establishing a calibration service for well-type ionization chambers used to characterize the strength of eBx sources prior to clinical use. The calibration approach involves establishing the well-chamber’s response to an eBx source whose air-kerma rate at a 50 cm distance is determined through a primary measurement performed using the Lamperti free-air ionization chamber. However, the free-air chamber measurements of charge or current can only be related to the reference air-kerma standard after applying several corrections, some of which are best determined via Monte Carlo simulation. To this end, a detailed geometric model of the Lamperti chamber was developed in the EGSnrc code based on the engineering drawings of the instrument. The egs-fac user code in EGSnrc was then used to calculate energy-dependent correction factors which account for missing or undesired ionization arising from effects such as: (1) attenuation and scatter of the x-rays in air; (2) primary electrons escaping the charge collection region; (3) lack of charged particle equilibrium; (4) atomic fluorescence and bremsstrahlung radiation. Results: Energy-dependent correction factors were calculated assuming a monoenergetic point source with the photon energy ranging from 2 keV to 60 keV in 2 keV increments. Sufficient photon histories were simulated so that the Monte Carlo statistical uncertainty of the correction factors was less than 0.01%. The correction factors for a specific eBx source will be determined by integrating these tabulated results over its measured x-ray spectrum. Conclusion: The correction factors calculated in this work are important for establishing a national standard for eBx which will help ensure that dose

  15. SU-E-T-552: Monte Carlo Calculation of Correction Factors for a Free-Air Ionization Chamber in Support of a National Air-Kerma Standard for Electronic Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: To use Monte Carlo radiation transport methods to calculate correction factors for a free-air ionization chamber in support of a national air-kerma standard for low-energy, miniature x-ray sources used for electronic brachytherapy (eBx). Methods: The NIST is establishing a calibration service for well-type ionization chambers used to characterize the strength of eBx sources prior to clinical use. The calibration approach involves establishing the well-chamber’s response to an eBx source whose air-kerma rate at a 50 cm distance is determined through a primary measurement performed using the Lamperti free-air ionization chamber. However, the free-air chamber measurements of charge or current can only be related to the reference air-kerma standard after applying several corrections, some of which are best determined via Monte Carlo simulation. To this end, a detailed geometric model of the Lamperti chamber was developed in the EGSnrc code based on the engineering drawings of the instrument. The egs-fac user code in EGSnrc was then used to calculate energy-dependent correction factors which account for missing or undesired ionization arising from effects such as: (1) attenuation and scatter of the x-rays in air; (2) primary electrons escaping the charge collection region; (3) lack of charged particle equilibrium; (4) atomic fluorescence and bremsstrahlung radiation. Results: Energy-dependent correction factors were calculated assuming a monoenergetic point source with the photon energy ranging from 2 keV to 60 keV in 2 keV increments. Sufficient photon histories were simulated so that the Monte Carlo statistical uncertainty of the correction factors was less than 0.01%. The correction factors for a specific eBx source will be determined by integrating these tabulated results over its measured x-ray spectrum. Conclusion: The correction factors calculated in this work are important for establishing a national standard for eBx which will help ensure that dose

  16. Distribution of kerma rate in the air inside of hemodynamic room for typical projections of interventionist cardiology procedures; Distribuicao da taxa de kerma no ar em uma sala de hemodinamica para projecoes tipicas de procedimentos de cardiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Mirtha Elizabet Gamarra

    2008-07-01

    The evaluation of dose to physicians involved in Interventional Cardiology (IC) is an extreme important matter due to the high and non-uniform distribution of dose values. The radiation control during each procedure is complex and the reasons for the high exposures have many different causes. Many international recommendations have already been written aiming the radiation protection optimization in IC. In Brazil, there is not any special orientation for the protection of those occupational persons, nor a specific legislation. The purpose of this work is to evaluate the air kerma rate at critical anatomic regions of the occupationally exposed staff that carry out IC procedures, in representative incidences in order to give subsidies for individual monitoring procedures implementation and to give more information about their radiation protection. The air kerma rate has been measured in the often used condition in the two more common IC procedures namely angiography and coronary angioplasty, using an adult patient simulator irradiated under RAO, LAO and AP projections for fluoro and digital acquisition modes. The measurements have been made in 45 points around the examination table at 5 different representatives heights of: eyes lens, thorax, hands, gonads and knees. AP projection shows the smaller scattered radiation contributions and a more homogeneous exposure distribution. The digital acquisition mode gives air kerma rates about 4 times higher than fluoro mode for LAO projection in the position occupied by the interventionist doctor, the anesthetist and the nursing staff. The most critical anatomic regions are: knees and gonads (without protection). On the physician hands position, values as high as 5 mGy/h have been measured, which can overpass, depending on the number of procedures done, the individual occupational annual limit. Therefore, in IC it is necessary to implement additional protection tools, elaborate safety guides (based on international experiences

  17. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    Energy Technology Data Exchange (ETDEWEB)

    Wunderle, K [Cleveland Clinic Foundation, Cleveland, OH& Wayne State University School of Medicine, Detroit, MI (United States); Rakowski, J [Wayne State University School of Medicine, Detroit, MI (United States); Dong, F [Cleveland Clinic Foundation, Cleveland, OH (United States)

    2015-06-15

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  18. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    International Nuclear Information System (INIS)

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  19. Image quality and volume computed tomography air kerma index (C{sub vol}) evaluation in Recife; Avaliacao da qualidade de imagem e do indice volumetrico de Kerma ar em tomografia computadorizada (C{sub vol}) em Recife

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marcos Ely Almeida

    2008-07-01

    The Computed Tomography (CT) is an important diagnostic imaging method, widely used. However, in spite of all the advantages and technologic advances within the CT scanners, the tomographic procedures result in high absorbed doses to patients. The main objective of this work was to perform a dosimetric study of CT scanners located at Recife and to evaluate the image quality on CT examinations in these equipment. The volume CT air kerma index (C{sub VOL}) and air kerma length product (P{sub KL,CT}) were estimated. These values were calculated using normalized weighted air kerma indexes in CT standard dosimetry phantoms ({sub n}C{sub W}), supplied by ImPACT group for several CT scanners, and the scan parameters of routine head, routine chest and hi-resolution chest CT exams performed at 20 institutions. The irradiation parameters of 15 adult patients for each CT procedure were registered at six participating centres, at which the phantom from the American College of Radiology (ACR) CT accreditation protocol was used for the image quality measurements. For routine head exams, the C{sub VOL} values varied between 12 and 58 mGy (at the posterior fossa) and 15 to 58 mGy (at the cerebrum) and the P{sub KL,CT}, from 150 to 750 mGy{center_dot}cm. The C{sub VOL} values for routine chest procedures varied from 3 to 26 mGy and the P{sub KL,CT}, between 120 and 460 mGy{center_dot}cm. In relation to Hi-resolution chest exams, C{sub VOL} values were from 1.0 to 2.7 mGy and the P{sub KL,CT} values varied between 24 and 67 mGy{center_dot}cm. The image quality evaluations results showed that almost all scanners presented at least one inadequacy. One of the equipment presented faults at 70% of the tests. With regard to the image noise, only two scanners presented acceptable results. From these results, it is possible to conclude that the volume CT air kerma index values are lower than the European reference levels. However, the image quality of these CT scanners does not attend the

  20. Uncertainty evaluation of the kerma in the air, related to the active volume in the ionization chamber of concentric cylinders, by Monte Carlo simulation; Avaliacao de incerteza no kerma no ar, em relacao ao volume ativo da camara de ionizacao de cilindros concentricos, por simulacao de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Lo Bianco, A.S.; Oliveira, H.P.S.; Peixoto, J.G.P., E-mail: abianco@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    To implant the primary standard of the magnitude kerma in the air for X-ray between 10 - 50 keV, the National Metrology Laboratory of Ionizing Radiations (LNMRI) must evaluate all the uncertainties of measurement related with Victtoren chamber. So, it was evaluated the uncertainty of the kerma in the air consequent of the inaccuracy in the active volume of the chamber using the calculation of Monte Carlo as a tool through the Penelope software

  1. Calculation of the uncertainty associated to the result of entrance surface air kerma for conventional radiology patients

    International Nuclear Information System (INIS)

    Radiation doses from diagnostic radiology are the largest contribution to the collective dose and the use of guidance (reference levels) has proven to be a tool for optimization of protection. Recently, with the support of the International Atomic Energy Agency (IAEA), eight countries of the Latin-American region have been working together on a programme to test methodologies for determining preliminary values of guidance levels for X-ray chest, lumbar spine and breast examinations. The approach used was to obtain entrance surface air kerma from measurements of X-ray tube outputs, corrected for distance and backscatter and later for real exposure parameters used with patients. For quality control, some of these values for a reduced number of patients were compared with direct TLD measurements directly placed on the patient during exposure. Given the number of parameters involved in the two methods, relatively large differences are deemed to be found in the comparison. The only way of deciding if measurements and calculations are outliers, for example, due to a systematic error or a mistake, is to compare these differences with the combined uncertainty. The aim of this paper is to present (in a detailed way) the methodology used in the pilot program ARCAL LXXV, the analyses of data performed within the survey and the estimated uncertainty. The parameters analyzed were: precision of the readings, positioning of the detector, reproducibility of the mAs and kV, long term stability of the instrument, radiation quality, kerma rate, radiation incidence, field size and field homogeneity, calibration factor of the equipment, temperature and pressure measurement, X-ray tube output curve adjustment, backscatter factor and focus-patient distance. The combined standard uncertainty for Ke in chest radiography in adult patients of standard complexion, was 12%, and the expanded uncertainty (k=2) was 24%. (author)

  2. Attenuation factors in terms of air kerma to ambient dose equivalent and effective dose for diagnostic X rays rooms

    International Nuclear Information System (INIS)

    In the present study, the attenuation of the quantities fluence and air kerma free-in-air by various layers of lead was compared with that of the quantities effective dose, E, and ambient dose equivalent, H*(d). This work aims to calculate the attenuation factors from 50 kV, 125 kV and 150 kV of X ray beams used for medical diagnostic, after transmission through barriers of lead. The X ray qualities used were those recommended by the Birch and Marshall for primary diagnostic X rays. Several lead layers were irradiated with a 50 cm x 50 cm field of primary X ray spectra. The transmitted spectra were calculated to obtain the attenuation factors for beams found in radiodiagnostic services. The calculations were done using the MCNPX Monte Carlo code and voxel model MAX. The values obtained were compared with data derived from the literature. In addition, attenuation factors for X ray qualities after penetration of lead layers were studied to get data which might be of interest in shielding of diagnostic rooms. (author)

  3. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the NIM, China and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D.; Wang, K.; Fan, Y.; Jin, S.; Yang, X.

    2016-01-01

    An indirect comparison of the standards for air kerma of the National Institute of Metrology (NIM), China and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in November 2015. The comparison result, evaluated as a ratio of the NIM and the BIPM standards for air kerma, is 0.9997 with a combined standard uncertainty of 2.7 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  4. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NMIJ and the BIPM

    Science.gov (United States)

    Kessler, C.; Kurosawa, T.; Mikamoto, T.

    2016-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Metrology Institute of Japan (AIST-NMIJ), Japan, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the Japan Radioisotope Association (JRIA) in April 2015. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NMIJ and the BIPM standards for reference air kerma rate, is 1.0036 with a combined standard uncertainty of 0.0054. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  5. Kerma in the air at entry surface in thorax pediatric examinations at public hospital in Parana, Brazil

    International Nuclear Information System (INIS)

    This work consisted in the evaluation of the entrance skin air kerma (ESAK) in pediatric chest x-ray examinations. A study of 186 exams in anterior-posterior, posterior-anterior and lateral projections was carried out for patients with ages ranging from 0 to 15 years. The ESAK was measured with the DoseCal software and Li-Fl thermoluminescent dosimeters. The results were compared with measurements done recently at the same place and with the reference dose values established by the European Community. It was observed that the optimization of the technique and the routine changes suggested in the previous study were not maintained. The charge (mAs) and the ESAK values found in the present study were much higher than the previous one, and the voltage (kVp) values found was lower. The results suggest that the implementation of the Quality Assurance Program could adequate these parameters to the established levels and keep the pediatric examinations more uniform. (author)

  6. COOMET regional comparison of national measurement standards of air kerma for 137Cs γ radiation at protection level

    Science.gov (United States)

    Büermann, L.; Oborin, A. V.; Milevsky, V. S.; Walwyn Salas, G.; Sukhishvili, S.; Ginga, I.; Ivanov, R.; Gudelis, A.; Gomola, I.

    2014-01-01

    Results are presented of the COOMET supplementary comparison of the national measurement standards for air kerma in 137Cs γ radiation at protection level (~10 mGy/h). Ten National Metrology Institutes from the COOMET organization and the International Atomic Energy Agency participated in this COOMET project no. 445. The PTB acted as pilot laboratory. Two of the participants, the SMU (Slovakia) and the NSC-'IM' (Ukraine) participated in the measurements but did not submit a valid report of results. The comparison reference value (CRV) was obtained as the mean result of the PTB and the VNIIM, both of which had previously taken part in the key comparison BIPM-RI(I)-K5. The degree of equivalence with the CRV was evaluated. The results were consistent within the relative standard uncertainties of the comparison ranging from 0.28% to 1.3% and deviated from the CRV by less than 1%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  7. Measuring instruments of the Physikalisch-Technische Bundesanstalt for realization of the units of the dosimetric quantities standard ion dose, photon-equivalent dose and air-kerma

    International Nuclear Information System (INIS)

    The realization of the units of the dosimetric quantities exposure, air-kerma and photon-equivalent dose is an important task of the Physikalisch-Technische Bundesanstalt. The report describes the measuring instruments and other technical equipment as well as the determination of the numerous corrections needed. All data and correction factors required for the realization of the units mentioned above are given in many diagrams and tables. (orig.)

  8. Evaluation of conversion coefficients relating air-kerma to H*(10) using primary and transmitted x-ray spectra in the diagnostic radiology energy range.

    Science.gov (United States)

    Santos, J C; Mariano, L; Tomal, A; Costa, P R

    2016-03-01

    According to the International Commission on Radiation Units and Measurements (ICRU), the relationship between effective dose and incident air-kerma is complex and depends on the attenuation of x-rays in the body. Therefore, it is not practical to use this quantity for shielding design purposes. This correlation is adopted in practical situations by using conversion coefficients calculated using validated mathematical models by the ICRU. The ambient dose equivalent, H*(10), is a quantity adopted by the IAEA for monitoring external exposure. Dose constraint levels are established in terms of H*(10), while the radiation levels in radiometric surveys are calculated by means of the measurements of air-kerma with ion chambers. The resulting measurements are converted into ambient dose equivalents by conversion factors. In the present work, an experimental study of the relationship between the air-kerma and the operational quantity ambient dose equivalent was conducted using different experimental scenarios. This study was done by measuring the primary x-ray spectra and x-ray spectra transmitted through materials used in dedicated chest radiographic facilities, using a CdTe detector. The air-kerma to ambient dose equivalent conversion coefficients were calculated from these measured spectra. The resulting values of the quantity ambient dose equivalent using these conversion coefficients are more realistic than those available in the literature, because they consider the real energy distribution of primary and transmitted x-ray beams. The maximum difference between the obtained conversion coefficients and the constant value recommended in national and international radiation protection standards is 53.4%. The conclusion based on these results is that a constant coefficient may not be adequate for deriving the ambient dose equivalent. PMID:26835613

  9. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NMIJ and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the NMIJ and the BIPM in the low-energy X-ray range. The results show the standards to be in agreement within the expanded uncertainty, although there is evidence of a trend in the results for different radiation qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  10. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NRC, Canada and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the NRC and the BIPM in the low-energy X-ray range. The results show the standards to be in agreement at the level of the combined standard uncertainty of 2.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  11. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the PTB, Germany and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the PTB, Germany and the BIPM in the low-energy X-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 2.1 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  12. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the BEV, Austria and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the BEV and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the combined standard uncertainty of 4.7 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  13. Spatial distribution of air kerma rate and impact of accelerating voltage on the quality of an ultra soft X-ray beam generated by a cold cathode tube in air

    International Nuclear Information System (INIS)

    Ultrasoft X-ray characteristic aluminum K alpha line (Al Kα with energy of 1.5 keV) is used in radiobiological experiments to study the effect of radiation on biological matter. A simple method to generate a continuous beam of those X-ray radiations is to bombarding an aluminum target with accelerated electrons using high voltage (HV). In this work, by varying the HV we study the characteristics of a photon beam generated by means of a cold cathode transmission X-ray tube. The anode is a thin (16 μm) aluminum foil supported by a copper grid. The spatial distribution of air kerma is measured using gafchromic films of HD-810 calibrated with a parallel plate free-air ionization chamber. We show that HV strongly modifies the energetic spectrum and air kerma rate as well as its uniformity and intensity in air. - Highlights: • We measured energy spectrum of X-ray beam. • We calibrate the Gafchromic films to measure air kerma of X-ray beam. • Spatial air kerma rate is determined and interpreted. • We define dimensions and position of future biological sample irradiation using Al Kα X-ray

  14. Comparison of the air kerma standards of the IAEA and the BIPM in mammography x-rays

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Czap, L.; Csete, I.; Gomola, I.

    2013-01-01

    The Dosimetry Laboratory of the International Atomic Energy Agency (IAEA), Seibersdorf, Austria, calibrates reference standards in mammography x-ray beams for IAEA/WHO SSDL Network members (more than 80 laboratories worldwide). As a signatory of the Mutual Recognition Arrangement (CIPM MRA), the IAEA laboratory maintains a Quality Management System (QMS) complying with ISO 17025 and requires updated 'supporting evidence' for its dosimetry calibration and measurement capabilities (CMC), first published in Appendix C of the CIPM MRA key comparison database in 2007. For this purpose, an indirect comparison has been made between the air kerma standards of the IAEA and the Bureau International des Poids et Mesures (BIPM) in the mammography x-ray range from 25 kV to 35 kV, using as transfer instruments two thin-window parallel-plate ionization chambers belonging to the IAEA. The IAEA and BIPM standards for mammography x-rays are shown to be in agreement within the standard uncertainty of the comparison of 5.5 parts in 103. This agreement can be used to support the calibration and measurements capabilities of the IAEA listed in Appendix C of the key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Coomet Project 445: Comparison of National Measurement Standards of Air Kerma for Cs-137 Gamma Radiation at Protection Level

    International Nuclear Information System (INIS)

    A COOMET supplementary comparison of the national measurement standards of air kerma for Cs-137 gamma radiation at protection level (∼10 mGy/h) was carried out between May 2011 and February 2013. Participants were VNIIM (Russia), BelGIM (Belarus), CPHR (Cuba), GEOSTM (Georgia), INSM (Moldova), NSC-'IM' (Ukraine), SMU (Slovakia), PTB (Germany), BIM (Bulgaria), VMT/FTMC (Lithuania) and the International Atomic Energy Agency (IAEA). The PTB acted as the pilot laboratory. The comparison reference value (CRV) was obtained as the mean of the results obtained by PTB and VNIIM, both of which had previously taken part in the key comparison BIPM-RI (I)-K5. Results will be published in Appendix B of the BIPM key comparison database (KCDB) using the identifier COOMET.RI(I)-S1 as soon as the Draft B report is accepted. The comparison was organized within an extended COOMET project (identified as Project 445/DE/08), the aim of which was not only to compare national standards but also for educational purposes. Some of the participants had taken part in such a comparison for the first time and, therefore, an introductory seminar was held at PTB in May 2011. The seminar was open for participation also to those countries of the COOMET region which did not participate in the comparison and to nonMRA signatories and countries without an approved quality management system in order to acquire measurement routine and theoretical as well as organizational knowledge for future comparisons. The main goal of this seminar was to prepare the participants for the procedure of having entries accepted for the CMC list in the metrological area of Ionising Radiation, Section I, x and gamma rays

  16. From reference air-kerma-rate to nominal absorbed dose-rate to water Paradigm shift in photon brachytherapy: ISO new work item proposal

    International Nuclear Information System (INIS)

    Full text: Over decades, photon radiation brachytherapy (BT) has proven worldwide as an essential modality of high precision radiation oncology for certain primary tumor sites. The dosimetric uncertainty of photon brachytherapy, however, is currently much larger than in external beam radiotherapy due to several factors including: calibration to the reference air-kerma-rate K.R K.R (or air-kerma strength), dose calculation model, dosimetric functions and dose measurement complexity, besides the geometrical dose uncertainties in high dose-gradient BT-fields. In addition, many photon sources are applied with quite different dosimetric properties requiring much skill from the medical physicist. This work proposes increased accuracy of brachytherapy through improvements in source calibration and clinical dosimetry methodology. Currently, BT-photon sources are calibrated free in air, at 100 cm distance, and in terms of K.R. By calibrating BT-photon sources directly to the TG-43U1 reference point at 1 cm in water, to be named the nominal absorbed dose-rate to water, D.w,1, the number of calibration steps in the traceability chain is reduced from 6 to 4, thus reducing the expanded uncertainty in dose delivery for patient treatment. With a target combined uncertainty of ucue.w,1 primary standards, which will soon become available for high energy and low energy, high and low dose-rate BT-photon sources. This is a paradigm shift that requires: international consensus, metrologic work and guidance. Thus, there is a need for an ISO standard based on and extending the AAPM TG-43U1 formalism. Taking into account the results and conclusions of the AAPM 2010 discussions, a draft for an ISO new work item proposal on Clinical dosimetry - Photon radiation sources for brachytherapy will be presented. This standardization project could be launched within ISO TC 85/SC 2/WG 22, in continuation of ISO 21439 (2009) for beta radiation sources. Clear terms and definitions are basic

  17. Air kerma national standard of Russian Federation for x-ray and gamma radiation. Activity SSDL/VNIIM in medical radiation dosimetry field

    International Nuclear Information System (INIS)

    Primary standard of unities air kerma and air kerma rate X-ray and gamma radiation, placed at VNIIM, consists of: plate-parallel free-air ionization chamber IK 10-60 for low-energy X-ray in the generating potential range from 10 to 50 kV; plate-parallel free-air ionization chamber IK 50-400 for medium-energy X-ray in the generating potential range from 50 to 300 kV; cavity cylindrical graphite chambers C1 and C30 with volumes 1 cm3 and 30 cm3 for reproduction and transmission the dimensions gamma radiation unities using Cs-137 and Co-60 sources. The next irradiation facilities are used at VNIIM: in low-energy X-ray range: a constant-potential high-voltage generator and a tungsten-anode Xray tube with inherent filtration of around 1 mm Be; in medium-energy X-ray range: set on the basis of an industrial X-ray apparatus Isovolt-400 and a tungsten-anode X-ray tube with inherent filtration of around 3,5 mm Al; in gamma radiations field: units with a radioactive sources Cs-137 with activity 140 and 1200 GBq and Co-60 with activity 120 GBq and irradiation set with a source from Co-60 (activity 3200 GBq). The last one belongs to Central Research Institute for Radiology and Roentgenology (CNIRRI). For measuring currents and charges of standard chambers we use electrometers such as Keithley of model 6517A and B7-45 manufactured by 'Belvar' (Republic Belarus). The reference radiation qualities L, N, H series according to ISO 4037 and the radiation qualities RQR, RQA and RQF according to IEC 61267 for calibration and verification of the therapeutic, diagnostic measurement means are realized in the low-energy and medium-energy X-ray standards. The VNIIM air kerma primary standard of has been participated in the international comparisons: key comparison BIPM.R1(I)-K1 for gamma radiation of Co-60 in 1997; supplementary comparisons BIPM.R1(I)-S10 for gamma radiation of Cs-137 in 1997; key comparison BIPM.R1(I)-K2 for low-energy X-ray range in 1998; key comparison BIPM.R1(I)-K3 for

  18. Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

    Science.gov (United States)

    Wunderle, Kevin A; Rakowski, Joseph T; Dong, Frank F

    2016-01-01

    The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma-area product (Pk,a) over a broad spectrum of X-ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma-area product meters (KAP meters) to measure X-ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state-of-the-art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC deter-mined at 100 kVp with copper (Cu) in the beam resulted in a deviation of < 5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ± 35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (~ 55-60 kVp) and large amount of Cu filtration (~ 0.6-0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify. PMID:27167287

  19. Comparison of the air-kerma standards of the NPL and the BIPM in the low and medium-energy X-ray ranges

    International Nuclear Information System (INIS)

    The air-kerma standards of the NPL and the BIPM have been compared in the low- and medium-energy x-ray ranges. The results for the low-energy comparison show the standards to be in agreement at the level of one standard uncertainty. At medium energies a slight trend with radiation quality is evident, with agreement at the level of one standard uncertainty for 100 kV rising to over two standard uncertainties for 250 kV. In relation to previous comparisons, the good stability of the standards over a period of twenty years is demonstrated. (authors)

  20. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the NIST, USA and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the NIST and the BIPM in the low-energy x-ray range. The results show the standards to be in general agreement at the level of the combined standard uncertainty for the comparison of 4.1 parts in 103, although the results for the different radiation qualities show variations that are larger than would be expected. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  1. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the ARPANSA and the BIPM in low-energy X-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the ARPANSA and the BIPM in the low-energy X-ray range. The results show the standards to be in agreement at the level of the combined standard uncertainty of 7.0 parts in 103 for the 10 kV radiation quality and 3.7 parts in 103 for all other beam qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  2. Recent regional key comparison results for air kerma and absorbed dose to water in X-rays and 60Co radiation

    International Nuclear Information System (INIS)

    Degrees of equivalence (DoE) of the national standards as a result of periodically organized supporting key or supplementary comparisons are essential to maintain the calibration and measurement capabilities CMC lines in the database of the CIPM MRA. All the primary and secondary' standard dosimetry laboratories belong to at least one of the APMP, AFRIMETS, COOMET, EURAMET, and SIM Regional Metrology Organizations. Most of their host country's NMIs have signed the CIPM MRA and these NMIs or Designated Institutes (DI) in 32 countries worldwide have published dosimetry CMC's. From these 941 claims, 222 relate to the calibration of a wide variety of dosemeters in term of air kerma or absorbed dose to water being used in diagnostic or therapy practice in hospitals. In the case of low and medium energy X-ray beam qualities, one regional key comparison (APMP.RI (I)-K3) has been published and has some results that do not fully support the stated uncertainties of the participants. The other two similar comparisons (APMP.RI (I)-K-2, SIM.RI (I)-K-2) are still ongoing. For air kerma of the 60Co beam from the APMP.RI(I)-K1, SIM.RI(I)-K1 and EURAMET.RI(I)-K1 comparisons there are two results among the twenty-one recently established DoE values that is outside the expanded uncertainty. Further technical details of regional comparisons including the stated uncertainty budgets for the calibration of a typical therapy ionization chamber will be presented in the poster. Concerning the future regional key and supplementary comparison program the most important issues are the following: - encourage the dosimetry laboratories to organise and coordinate these comparisons, - more economic arrangement of the X-ray comparisons on the basis of the generic beam qualities of the 85 standard qualities, - organization of supplementary comparisons in term of air kerma length to support the CT dose measurements, - using dedicated mammography X-ray tube for air kerma comparisons of mammography

  3. Proposed specification for a primary standard of air kerma for sup 6 sup 0 Co, sup 1 sup 3 sup 7 Cs and sup 1 sup 9 sup 2 Ir gamma-ray sources

    CERN Document Server

    Angliss, R; Nutbrown, R

    2001-01-01

    The three cavity chambers, the mean response of which constitutes the primary standard of air kerma for sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays in the United Kingdom, have been in continuous, almost daily, use at the National Physical Laboratory (NPL) since 1956. These chambers were initially designed for use with 2 MV X-rays at therapy level air kerma rates. However since 1978 they have also been used for protection level air kerma rates, initially, with X-rays generated at 1 MV and 2 MV and more recently with sup 6 sup 0 Co and sup 1 sup 3 sup 7 Cs gamma-rays. They have been used for therapy level air kerma calibrations with sup 6 sup 0 Co gamma-rays since 1997 following the demise of the NPL 2 MV Van de Graaff generator. This report describes the proposals for a new primary standard and the methods that will be used to give a better performance than the present standard when used with air kerma rates from as high as 1 Gy min sup - sup 1 down to 10 mGy hr sup - sup 1. The design will also seek to...

  4. Energy dependence of the air kerma response of a liquid ionization chamber at photon energies between 8 keV and 1250 keV

    International Nuclear Information System (INIS)

    Full text: In its recent reports on cardiovascular brachytherapy the DGMP recommends the source strength of brachytherapy sources being characterized in terms of absorbed dose to water at a distance of 2 mm from the central axis of the source. As a consequence, the response of a detector suitable for characterizing such sources with respect to absorbed dose to water should depend only to a small extent on radiation energy. Additionally, the detection volume of the detector has to be sufficiently small for the necessary spatial resolution to be obtained. The liquid ionization chamber as described in seems to be a promising means for this type of measurements. The two components of the ionization liquid (TMS and isooctane) can be mixed in a ratio which ensures that the mass-energy absorption coefficient of the resulting mixture deviates from that of water by less than ±15 % down to photon energies of 10 keV. Due to the high density of the ionization medium, the spacing between the two electrodes of the ionization chamber can be made as small as a few tenths of a millimeter and still the resulting ionization current is sufficiently large. The ionization chamber used in the present investigation is a plane parallel chamber 5 mm in diameter and of 0.3 mm electrode spacing. The ionization medium is a mixture of 40 % TMS and 60 % isooctane. The irradiations were carried out with the ISO wide spectra series with tube voltages between 10 kV and 300 kV and with 137Cs and 60Co γ-radiation. As a first step, the response of the liquid ionization chamber was investigated with respect to air kerma instead of absorbed dose to water. Although the mass-energy absorption coefficient of the liquid deviates from that of air by less than ±10 % over the photon energy range, the measured chamber response varies by a factor of about 3.5. Monte Carlo calculations carried out with EGSnrc show a variation of the chamber response smaller than ±20 %. Measurements of the ion yield of the

  5. Assessment of protocols in cone-beam CT with symmetric and asymmetric beams usingeffective dose and air kerma-area product

    International Nuclear Information System (INIS)

    This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using thermoluminescent dosimeter (TLD) and the air kerma-area product (PKA) as the kerma index. The measurements were performed on two protocols used to obtain an image of the maxilla–mandible using the equipment GENDEX GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm×8.5 cm-maxilla/mandible) and protocol [GX2] symmetrical beam (8.5 cm×8.5 cm-maxillary/mandible). LiF dosimeters inserted into a female anthropomorphic phantom were used. For both protocols, the value of PKA was evaluated using a PTW Diamentor E2 meter and the multimeter Radcal Rapidose system. The results obtained for the effective dose/PKA were separated by protocol image. [GX1]: 44.5 µSv/478 mGy cm2; [GX2]: 54.8 µSv/507 mGy cm2. Although the ratio of the diameters (14 cm/8.5 cm)=1.65, the ratio of effective dose values (44.5 µSv/54.8 µSv)=0.81, that is, the effective dose of the protocol with extended diameter is 19% smaller. The PKA values reveal very similar results between the two protocols. For the cases where the scanner uses an asymmetric beam to obtain images with large diameters that cover the entire face, there are advantages from the point of view of reducing the exposure of patients when compared to the use of symmetrical beam and/or to FOV images with a smaller diameter. - Highlights: • The study relies on the comparison of two image protocols in CBCT: symmetrical and asymmetrical FOV. • Effective dose assessment for symmetrical and asymmetrical FOV. • Measurements of air kerma-area product for CBCT with symmetrical and asymmetrical FOV

  6. Calculation of the correction factors for the primary standard of kerma in the air at the LNMRI-IRD, Rio de Janeiro, Brazil; Calculo de fatores de correcao para o padrao primario em kerma no ar do LNMRI-IRD, Rio de Janeiro, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cosme Norival Mello da, E-mail: cosme@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    In order to determine the primary standardization in terms of kerma in the air, a graphite ionization chamber is used for calculation some correction factors. A program was elaborated, using the Monte Carlo Penelope for simulate the CC01-110 at the LNMRI/IRD, Rio de Janeiro, Brazil

  7. Construction of a laboratory for the implantation of primary standardization of the magnitude kerma in the air for the X-ray beams used in mammography; Construcao de um laboratorio para a implantacao da padronizacao primaria da grandeza kerma no ar para os feixes de raios X empregados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Cardozo, W.L.; Magalhes, L.A.A.M.F.; Peixoto, J.G.P., E-mail: wagnerlc@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI)

    2009-07-01

    Aiming to diminish the uncertainty in each phase of the metrological chain, and the uncertainty in dosimetry processed at the X-ray beam applied in the mammography, is necessary that the LNMRI/IRD to develop a reference primary standard for the absolute form to the magnitude kerma in the air

  8. Kerma in the air at entry surface in thorax pediatric examinations at public hospital in Parana, Brazil; Kerma no ar na superficie de entrada em exames pediatricos de torax em hospital publico no Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Amanda; Porto, Lorena; Bunick, Ana; Paschuk, Sergei; Denyak, Valeriy, E-mail: schelin@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Schelin, Hugo; Tilly, Joao, E-mail: joao.tilly@derax.com.b [DERAX Desenvolvimento Radiologico, Curitiba, PR (Brazil); Khoury, Helen, E-mail: hjkhoury@gmail.co [Universidade Federal de Pernambuco (DOIN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Dosimetria e Instrumentacao Nuclear; Ferreira, Jose [Universidade Estadual do Oeste do Parana (UNIOESTE), Cascavel, PR (Brazil)

    2011-07-01

    This work consisted in the evaluation of the entrance skin air kerma (ESAK) in pediatric chest x-ray examinations. A study of 186 exams in anterior-posterior, posterior-anterior and lateral projections was carried out for patients with ages ranging from 0 to 15 years. The ESAK was measured with the DoseCal software and Li-Fl thermoluminescent dosimeters. The results were compared with measurements done recently at the same place and with the reference dose values established by the European Community. It was observed that the optimization of the technique and the routine changes suggested in the previous study were not maintained. The charge (mAs) and the ESAK values found in the present study were much higher than the previous one, and the voltage (kVp) values found was lower. The results suggest that the implementation of the Quality Assurance Program could adequate these parameters to the established levels and keep the pediatric examinations more uniform. (author)

  9. Calculation of conversion factor of Kerma in the air for ambient dose equivalent in radiotherapy; Calculo dos fatores de conversao de Kerma no ar para equivalente de dose ambiental em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Marco Antonio Frota

    2000-03-01

    This work aims to estimate the average conversion factor of Kerma in air to H {sup *} (10) using photon beams coming from clinic linear accelerators, transmitted through concrete walls of a radiotherapic treatment room. The transmitted photon spectra by both 1 meter and 2 meters concrete walls, in an area of 40 x 40 cm{sup 2}, were calculated when the primary beam impart in an angle of 0 deg. The (secondary) photon beams transmitted respectively by 0,5 meter, 1,0 meter, 1,0 meter and 2,0 meter concrete walls, after they scattered by an angle of 90 deg in a cylindric phantom inside the room, were also determined. Generally, 50 millions of histories were computed for each simulation made for the primary beam. For the 90 deg spread, the number of histories was 100 millions. The computational code used on this work was the MCNP4B. The most common clinic accelerators used on radiotheraphic treatments were used on this work CLINAC-4, CLINAC-6, CLINAC-18 and CLINAC-2500. From the spectra analysis obtained in this work, it was possible to dispose the conversion factor for realistic beams found in radiotherapeutic establishment. (author)

  10. Comparisons of the standards for air kerma of the PTB and the BIPM for 60Co and 137Cs gamma radiation

    International Nuclear Information System (INIS)

    Direct comparisons of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB, Germany) and of the Bureau International des Poids et Mesures (BIPM) were carried out in the 60Co and 137 Cs radiation beams of the BIPM in 2000. The results, expressed as ratios of the PTB and the BIPM standards for air kerma, indicate a relative difference in 60Co of 9.9 x 10-3 with a combined standard uncertainty of 1.8 x 10-3, and in 137Cs of 6.4 x 10-3 with a combined standard uncertainty of 2.8 x 10-3. The earlier comparisons in 60Co γ rays made in 1971 (direct) and 1989 (indirect) resulted in an agreement of the two standards within 2 x 10-3. The differences obtained now are due to the application of new correction factors for wall effects and point source non-uniformity of the beam, kwall and kpn, for the PTB standards, which were calculated using Monte Carlo methods. (authors)

  11. Use of a new breast phantom for dosimetric determination of incident air kerma and mean glandular dose in digital mammography system

    International Nuclear Information System (INIS)

    Mammography aims to achieve a high image quality associated with a dose in the patient as low as feasible. Values of average glandular dose, DG, can be obtained by means of two dosimetric methods: one based on the measurement of incident air kerma, Ki, associated with tables of conversion factors that depend on the half value layer, the thickness and the glandular composition of the breast. And the one that makes the measure directly to thermoluminescent dosimeters, TLDs, placed in a new dosimetric phantom. Thus, this study aims to determine the incident air kerma (Ki) and average glandular dose (DG) applied on patients in a digital mammography system (DR) using the phantom dosimetric developed. Another objective is to compare the results with the values of DG determined from Ki and also with the values of Ki and DG indicated in the examination of each patient by the digital mammography unit. The result of the average values measured in 77 patients with compressed breast thickness within the range of 5.5 cm and 6.5 cm, shows that the Ki values ranged around 7.9% between the methods of action. The result of the values of DG ranged around 14.7% between the two methods of action. It is observed that the estimate of DG by the software is higher than the values measured with the dosimetric phantom. (author)

  12. Comparisons of the standards for air kerma of the PTB and the BIPM for {sup 60}Co and {sup 137}Cs gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Allisy-Roberts, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); Buermann, L.; Kramer, H.M. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2005-11-15

    Direct comparisons of the standards for air kerma of the Physikalisch-Technische Bundesanstalt (PTB, Germany) and of the Bureau International des Poids et Mesures (BIPM) were carried out in the {sup 60}Co and {sup 137} Cs radiation beams of the BIPM in 2000. The results, expressed as ratios of the PTB and the BIPM standards for air kerma, indicate a relative difference in {sup 60}Co of 9.9 x 10{sup -3} with a combined standard uncertainty of 1.8 x 10{sup -3}, and in {sup 137}Cs of 6.4 x 10{sup -3} with a combined standard uncertainty of 2.8 x 10{sup -3}. The earlier comparisons in {sup 60}Co {gamma} rays made in 1971 (direct) and 1989 (indirect) resulted in an agreement of the two standards within 2 x 10{sup -3}. The differences obtained now are due to the application of new correction factors for wall effects and point source non-uniformity of the beam, k{sub wall} and k{sub pn}, for the PTB standards, which were calculated using Monte Carlo methods. (authors)

  13. Estimation of mean-glandular dose from monitoring breast entrance skin air kerma using a high sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeter system in mammography

    International Nuclear Information System (INIS)

    Estimation of mean-glandular dose (MGD) has been investigated in recent years due to the potential risks of radiation-induced carcinogenesis associated with the mammographic examination for diagnostic radiology. In this study, a new technique for immediate readout of breast entrance skin air kerma (BESAK) using high sensitivity MOSFET dosimeter after mammographic projection was introduced and a formula for the prediction of tube output with exposure records was developed. A series of appropriate conversion factors was applied to the MGD determination from the BESAK. The study results showed that signal response of the high sensitivity MOSFET exhibited excellent linearity within mammographic dose ranges, and that the energy dependence was less than 3% for each anode/filter combination at the tube potentials 25-30 kV. Good agreement was observed between the BESAK and the tube exposure output measurement for breasts thicker than 30 mm. In addition, the air kerma estimated from our prediction formula provided sufficient accuracy for thinner breasts. The average MGD from 120 Asian females was 1.5 mGy, comparable to other studies. Our results suggest that the high sensitivity MOSFET dosimeter system is a good candidate for immediately readout of BESAK after mammographic procedures

  14. Primary standardization of the HDR 192Ir source in terms of air kerma strength

    International Nuclear Information System (INIS)

    Establishing a primary standard of AKS at the Standards Laboratory and offering traceable calibration to all the hospitals that make use of HDR 192Ir, in brachytherapy is important. With this objective, the primary standardization of the HDR 192Ir source was undertaken. Details of the work are presented

  15. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the CMI, Czech Republic and the BIPM in mammography x-rays

    Science.gov (United States)

    Kessler, C.; Burns, D.; Roger, P.; Sochor, V.

    2016-01-01

    A first key comparison has been made between the air-kerma standards of the CMI, Czech Republic and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 3.5 parts in 103. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 1 part in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. KEY COMPARISON Comparison of the standards of air kerma of the ENEA-INMRI and the BIPM for 137Cs gamma rays

    Science.gov (United States)

    Allisy-Roberts, P. J.; Kessler, C.; Toni, M.; Bovi, M.

    2010-01-01

    A comparison of the standards of air kerma of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI) and of the Bureau International des Poids et Mesures (BIPM) was carried out in 137Cs radiation in 1998. The comparison result, updated for changes in the standards in 2003 and 2009, is 0.9927 (0.0067) and demonstrates that the ENEA-INMRI and BIPM standards are in agreement within the uncertainties. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  17. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD

    International Nuclear Information System (INIS)

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air Κα·, dose speed absorbed in water Dα·, and speed absorbed dose in air Dα·, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups σω and that of long term by means of the standard deviation among groups σβ, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) Κα·, in radiation field of 60Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) Dα),en radiation field of 60Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of 90Sr-90Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases σβ, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of σβ. For example with sizes of subgroup η∼ 30 data, or with a number of subgroups κ≥. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the determinations of the temperature to diminish their influence in the U. c. The percentage difference of the magnitudes dosemeters carried out by it patterns are consistent with U certain. However, it is necessary to diminish the

  18. Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

    International Nuclear Information System (INIS)

    Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC was benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (∼8 – 100 keV) and 05ID-2 (∼20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ∼ 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors

  19. Poster — Thur Eve — 24: Commissioning and preliminary measurements using an Attix-style free air ionization chamber for air kerma measurements on the BioMedical Imaging and Therapy beamlines at the Canadian Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D [Department of Oncology, University of Alberta, Edmonton, AB (Canada); McEwen, M; Shen, H [Ionizing Radiation Standards, National Research Council of Canada, Ottawa, ON (Canada); Siegbahn, EA [Department of Medical Physics, Stockholm University, Stockholm (Sweden); Fallone, BG; Warkentin, B [Department of Oncology, University of Alberta, Edmonton, AB (Canada); Department of Medical Physics, Cross Cancer Institute, Edmonton, AB (Canada)

    2014-08-15

    Synchrotron facilities, including the Canadian Light Source (CLS), provide opportunities for the development of novel imaging and therapy applications. A vital step progressing these applications toward clinical trials is the availability of accurate dosimetry. In this study, a refurbished Attix-style (cylindrical) free air chamber (FAC) is tested and used for preliminary air kerma measurements on the two BioMedical Imaging and Therapy (BMIT) beamlines at the CLS. The FAC consists of a telescoping chamber that relies on a difference measurement of collected charge in expanded and collapsed configurations. At the National Research Council's X-ray facility, a Victoreen Model 480 FAC was benchmarked against two primary standard FACs. The results indicated an absolute accuracy at the 0.5% level for energies between 60 and 150 kVp. A series of measurements were conducted on the small, non-uniform X-ray beams of the 05B1-1 (∼8 – 100 keV) and 05ID-2 (∼20 – 200 keV) beamlines for a variety of energies, filtrations and beam sizes. For the 05B1-1 beam with 1.1 mm of Cu filtration, recombination corrections of less than 5 % could only be achieved for field sizes no greater than 0.5 mm × 0.6 mm (corresponding to an air kerma rate of ∼ 57 Gy/min). Ionic recombination thus presents a significant challenge to obtaining accurate air kerma rate measurements using this FAC in these high intensity beams. Future work includes measurements using a smaller aperture to sample a smaller and thus more uniform beam area, as well as experimental and Monte Carlo-based investigation of correction factors.

  20. Neutron kerma factors and water equivalence of some tissue substitutes

    International Nuclear Information System (INIS)

    The Kerma factors and Kerma relative to the air and water of 24 compounds that are used as tissue substitutes were calculated for neutron energies ranging from 2.53×10−8 to 29 MeV. The Kerma ratios of the tissue substitutes relative to air and water were calculated. The water equivalence of the selected tissue substitutes was observed above neutron energies of 100 eV. The Kerma ratio relative to the air for poly-vinylidene fluoride and Teflon were nearest to unity at very low energy (up to 1 eV) and above 63 eV, respectively. It was found that the natural rubber was a water-equivalent tissue substitute compound. The results of the Kerma factors in our investigation show good agreement with those published in ICRU-44. We found that at higher neutron energies, the Kerma factors and Kerma ratios of the selected tissue substitute compounds were approximately the same, but though the differences were large for energies below 100 eV. - Highlights: • We calculated the neutron kerma factors of tissue substitutes up to 29 MeV. • Water equivalence was observed above neutron energy 100 eV. • Natural rubber was found to be a water equivalent material. • Kerma factors are in agreement with those published in literatures

  1. Comparison of air kerma measurements for tungsten anode based mammography x-ray beam qualities (EURAMET.RI(I)-S4.1)

    Science.gov (United States)

    Csete, I.; Büermann, L.; Gomola, I.

    2016-01-01

    A comparison of the air kerma standards for x-radiation qualities used in mammography was performed between the PTB and the IAEA. Two reference-class ionization chamber types Radcal RC6M and Magna A650 of the IAEA and tungsten anode based beam qualities with Mo and Al external filtrations (W+Mo, W+Al) established at both laboratories were selected for the comparison. The calibration coefficients, NK_air, were determined for the transfer chambers at the PTB in May 2015 and before and after this at the IAEA Dosimetry Laboratory. The results show good agreement, to be well within the 0.55 % standard uncertainty of the comparison. Correction factors to determine NK_air for these beam qualities based on calibration in RQR-M mammography beam qualities, established according to the IEC 61267 standard, were also calculated for the Radcal RC6M, 10X5-6M, and Magna A650 types of chambers. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  2. Conversion coefficients from air kerma to personal dose equivalent H{sub p}(3) fir eye-lens dosimetry; Coeficients de conversion du kerma dans l'air a l'equivalent de dose individuel H{sub p}(3) pour la dosimetrie du cristalin

    Energy Technology Data Exchange (ETDEWEB)

    Daures, J.; Gouriou, J.; Bordy, J.M

    2009-07-01

    This work has been performed within the frame of the European Union ORAMED project (Optimization of Radiation protection for Medical staff). The main goal of the project is to improve standards of protection for medical staff for procedure resulting in potentially high exposures and to develop methodologies for better assessing and for reducing exposures to medical staff. The Work Package WP2 is involved in the development of practical eye lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP code of the conversion factors related to the operational quantity H{sub p}(3). A set of energy and angular dependent conversion coefficients H{sub p}(3)/K{sub air} in the new proposed square cylindrical phantom of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE. The H{sub p}(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At low photon energy, up to 1 MeV, the two sets of conversion coefficients are consistent. Nevertheless, the differences increase at higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the code MCNP published by ENEA, agree with the kerma approximation calculations with PENELOPE. They are coherent with previous calculations in phantoms different in shape. But above 1 MeV, differences between conversion coefficient values calculated with the absorbed dose and with kerma approximation are significantly increasing, especially at low incidence angles. At those energies the electron transport has to be simulated. (author)

  3. Neutron kerma factors, and water equivalence of some tissue substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad, 580003 (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    The kerma factors and kerma relative to air and water of 24 compounds used as tissue substitutes were calculated for neutron energy from 2.53 x 10{sup -8} up to 29 MeV. The kerma ratio of the tissue substitutes relative to air and water were calculated by the ratio of kerma factors of the tissue substitute to air and water respectively. The water equivalence of the selected tissue substitutes was observed above neutron energies 100 eV. Kerma ratio relative to the air for Poly-vinylidene fluoride and Teflon are found to be nearest to unity in very low energy (up to 1 eV) and above 63 eV respectively. It was found that the natural rubber as a water equivalent tissue substitute compound. The results of the kerma factors in our investigation shows a very good agreement with those published in ICRU-44. We found that at higher neutron energies, the kerma factors and kerma ratios of the selected tissue substitute compounds are approximately same, but differences are large for energies below 100 eV. (Author)

  4. High strength air-dried aerogels

    Science.gov (United States)

    Coronado, Paul R.; Satcher, Jr., Joe H.

    2012-11-06

    A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

  5. Estudo comparativo da qualidade da imagem e do kerma, de entrada e de saída, em simulador de tórax utilizando sistemas analógico e digitalizado CR de aquisição de imagens Comparative study of image quality and entrance and exit air kerma measurements on chest phantom utilizing analog and CR digital imaging systems

    Directory of Open Access Journals (Sweden)

    Renata Matos da Luz

    2010-02-01

    Full Text Available OBJETIVO: O processo de migração de sistemas analógicos para digitalizados, para aplicações diagnósticas, requer cuidados específicos, a fim de manter a qualidade das imagens e minimizar a dose no paciente. Este trabalho tem como objetivo analisar e comparar a qualidade da imagem e o kerma num simulador não antropomórfico de tórax gerados por sistemas analógicos e digitalizados CR. MATERIAIS E MÉTODOS: Foram analisados a qualidade da imagem e o kerma, de entrada e saída, no simulador para dois equipamentos de raios X diferentes (Siemens e Emic, com diferentes sistemas de retificação de onda (12 pulsos e alta frequência. Ambos os sistemas (analógico e digitalizado estavam sendo utilizados no mesmo local. Foram geradas imagens em filme e em image plates. RESULTADOS: Foi observado aumento na tensão e/ou na carga transportada pelo tubo de raios X quando houve a migração para o sistema CR, para manutenção das características diagnósticas da imagem. Isto resultou em aumento de kerma coletado. CONCLUSÃO: As maiores diferenças determinadas (aumento de dose e redução da qualidade da imagem foram observadas no equipamento com retificação de onda de 12 pulsos e transdutor de imagem CR (image plates.OBJECTIVE: The process of migration from analog to digital imaging system requires specific attention to preserve images quality and minimizing the dose to the patients. The present study was aimed at analyzing and comparing images quality and entrance and exist air kerma measurements in a non-anthropomorphic chest phantom with analog and CR digital imaging systems. MATERIALS AND METHODS: Two different X-ray units (Siemens and Emic with different wave rectification systems (12-pulse and high-frequency were utilized in a single institution along the process of migration from analog to CR digital imaging system. Images were acquired on films and image plates. RESULTS: An increase on the X-ray tube peak voltage and/or load was observed

  6. Radiological investigations at the "Taiga" nuclear explosion site, part II: man-made γ-ray emitting radionuclides in the ground and the resultant kerma rate in air.

    Science.gov (United States)

    Ramzaev, V; Repin, V; Medvedev, A; Khramtsov, E; Timofeeva, M; Yakovlev, V

    2012-07-01

    Samples of soil and epigeic lichens were collected from the "Taiga" peaceful nuclear explosion site (61.30°N 56.60°E, the Perm region, Russia) in 2009 and analyzed using high resolution γ-ray spectrometry. For soil samples obtained at six different plots, two products of fission ((137)Cs and (155)Eu), five products of neutron activation ((60)Co, (94)Nb, (152)Eu, (154)Eu, (207)Bi) and (241)Am have been identified and quantified. The maximal activity concentrations of (60)Co, (137)Cs, and (241)Am for the soils samples were measured as 1650, 7100, and 6800 Bq kg(-1) (d.w.), respectively. The deposit of (137)Cs for the top 20 cm of soil on the tested plots at the "Taiga" site ranged from 30 to 1020 kBq m(-2); the maximal value greatly (by almost 3 orders of magnitude) exceeded the regional background (from global fallout) level of 1.4 kBq m(-2). (137)Cs contributes approximately 57% of the total ground inventory of the man-made γ-ray emitters for the six plots tested at the "Taiga" site. The other major radionuclides -(241)Am and (60)Co, constitute around 40%. Such radionuclides as (60)Co, (137)Cs, (241)Am, and (207)Bi have also been determined for the epigeic lichens (genera Cladonia) that colonized certain areas at the ground lip produced by the "Taiga" explosion. Maximal activity concentrations (up to 80 Bq kg(-1) for (60)Co, 580 Bq kg(-1) for (137)Cs, 200 Bq kg(-1) for (241)Am, and 5 Bq kg(-1) for (207)Bi; all are given in terms of d.w.) have been detected for the lower dead section of the organisms. The air kerma rates associated with the anthropogenic sources of gamma radiation have been calculated using the data obtained from the laboratory analysis. For the six plots tested, the kerma rates ranged from 50 to 1200 nGy h(-1); on average, 51% of the dose can be attributed to (137)Cs and 45% to (60)Co. These estimates agree reasonably well with the results of the in situ measurements made during our field survey of the "Taiga" site in August

  7. APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.H.; Hwang, W.S. [Institute of Nuclear Energy Research, Longtan, Taiwan (China); Kotler, L.H.; Webb, D.V. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie (Australia); Buermann, L. [Physikalisch Technische Bundesanstalt, Braunschweig (Germany); Burns, D.T. [Bureau International de Poids et Mesures, 92 - Sevres (France); Takeyeddin, M. [Atomic Energy Commission, Damascus (Syrian Arab Republic); Shaha, V.V. [Bhabha Atomic Research Centre, Mumbai (India); Srimanoroth, S. [Department of Medical Sciences, Nonthaburi (Thailand); Meghzifene, A. [International Atomic Energy Agency, Vienna (Austria); Hah, S.H.; Chun, K.J. [Korea Research Institute of Standards and Science, Yusong (Korea, Republic of); Kadni, T.B. [Malaysian Nuclear Agency, Kajang (Malaysia); Takata, N. [National Metrology Institute of Japan, Tsukuba (Japan); Msimang, Z. [National Metrology Institute of South Africa, Pretoria (South Africa)

    2008-10-15

    The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. (authors)

  8. APMP/TCRI key comparison report of measurement of air kerma for medium-energy x-rays (APMP.RI(I)-K3)

    International Nuclear Information System (INIS)

    The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. The results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4%. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories. (authors)

  9. Modelling the contribution of individual radionuclides to the total gamma air kerma rate for the sediments of the Ribble Estuary, NW England

    International Nuclear Information System (INIS)

    The aim of this study was to test the performance of a published dose-rate model, investigate the contribution of individual radionuclides to the total gamma air kerma rate (GAKR) and derive external doses to man in the Ribble Estuary, NW England. GAKRs were measured and sediment cores were collected in order to determine radionuclide specific activities with depth. The latter values were used as input data for the external dose-rate model. The model has a slight tendency to over-predict the GAKR, but, on average, the model predictions fall within ±26% of the measured value. Improvements, in the present case, might be made by accounting for core shortening and variations in soil density in the input data. The model predicted that, for exposed intertidal mud sites, a range of GAKRs between 0.011 and 0.022 μGy h-1 was attributable to Springfields discharges alone. The contribution due to 234mPa and 234Th ranged between 20 and 60%. An excess GAKR (GAKR arising from anthropogenic emissions alone) of 0.139-0.150 μGy μGy h-1, used in conjunction with relevant habit-survey data (for a potential critical group) and conversion factors, yielded a dose to man of 0.029-0.031 mSv year-1. (author)

  10. Air kerma to personal dose equivalent conversion factors for ICRU and ISO recommended slab phantoms for photons from 20 keV to 1 MeV

    International Nuclear Information System (INIS)

    The present report summarizes the studies carried out at ENEA-AMB-PRO-IRP (Institute for Radiation Protection) that were addressed to the determination of air kerma to personal dose equivalent conversion coefficients for two practical phantoms as proposed by ICRU (International Commission for Radiation Units and Measurements) and by ISO (International Standard Organization) for photon personal dosimeters' calibration procedure. The analyses, developed using the MCNP Monte Carlo code, were mainly aimed at establishing which of the two proposed phantoms better approximates the ICRU theoretical one. Furthermore a complete tabulation of the conversion coefficients is supplied for monoenergetic photon beams from 20 keV to 1 MeV as well as for the two ISO X-ray reference series Wide Spectrum and Narrow Spectrum. The study has been performed in the framework of the CEC Contract F13P-CT92-0064 'The Measurement of the Spectral and Angular Distribution of External Radiations in Workplace and Implications for Personal Dosimetry

  11. 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

    International Nuclear Information System (INIS)

    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)

  12. Study of the spatial variation of the air kerma backscatter factor on the standard ISO phantom, with a Co-60 irradiator

    International Nuclear Information System (INIS)

    Personal dosimeters should be calibrated on the surface of the ISO water phantom. For this purpose dose values should present a uniform distribution over the calibration area of diameter dF. To determine the boundary of the uniform dose area, two complementary approaches are purposed: the experimental and the numerical simulation. This article presents the results of Monte Carlo calculations and experimental determinations of the spatial variation of the air kerma backscatter factor on the ISO water phantom surface performed for the Co-60 gamma radiation quality. The experimental B values on the center of the phantom surface was 1.04 and dF was 30 cm. However, the experimental determination of the variation of B along the axis of the phantom is a very consuming time process and is very sensitive to the positioning of the ionisation chamber. The methodology advanced in this work allows the knowledge of values of B along the apothem and diagonal axis using only one experimental value the B value on the center of the phantom and taking into account the relative variation of B from the simulation results. (author)

  13. KEY COMPARISON: COOMET.RI(I)-K1 comparison of national measurement standards of air kerma for 60Co γ radiation

    Science.gov (United States)

    Büermann, L.; Oborin, A. V.; Dobrovosky, J.; Milevsky, V. S.; Walwyn Salas, G.; Lapenas, A.

    2009-01-01

    Results are presented of the COOMET key comparison of the national measurement standards of air kerma for 60Co γ radiation. Participants of the comparison were PTB (Germany, pilot institute), VNIIM (Russia), SMU (Slovakia), BelGIM (Belarus), CPHR (Cuba) and RMTC (Latvia). PTB, VNIIM and SMU had previously taken part in a key comparison with the Bureau International de Poids et Mesures (BIPM) and operated as link laboratories in order to evaluate the degree of equivalence of the participants' results with the key comparison reference value. These data form the basis of the results entered into the BIPM key comparison database for comparison COOMET.RI(I)-K1. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  14. Comparison between absorbed dose to water standards established by water calorimetry at the LNE-LNHB and by application of international air-kerma based protocols for kilovoltage medium energy x-rays

    International Nuclear Information System (INIS)

    Nowadays, the absorbed dose to water for kilovoltage x-ray beams is determined from standards in terms of air-kerma by application of international dosimetry protocols. New standards in terms of absorbed dose to water has just been established for these beams at the LNE-LNHB, using water calorimetry, at a depth of 2 cm in water in accordance with protocols. The aim of this study is to compare these new standards in terms of absorbed dose to water, to the dose values calculated from the application of four international protocols based on air-kerma standards (IAEA TRS-277, AAPM TG-61, IPEMB and NCS-10). The acceleration potentials of the six beams studied are between 80 and 300 kV with half-value layers between 3.01 mm of aluminum and 3.40 mm of copper. A difference between the two methods smaller than 2.1% was reported. The standard uncertainty of water calorimetry being below 0.8%, and the one associated with the values from protocols being around 2.5%, the results are in good agreement. The calibration coefficients of some ionization chambers in terms of absorbed dose to water, established by application of calorimetry and air-kerma based dosimetry protocols, were also compared. The best agreement with the calibration coefficients established by water calorimetry was found for those established with the AAPM TG-61 protocol. (paper)

  15. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD; Cartas de control e incertidumbres de los patrones de kerma en aire, dosis absorbida en agua y dosis absorbida en aire del LSCD

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, M.T.; Tovar M, V.M.; Cejudo A, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2005-12-15

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air {kappa}{sub {alpha}}{sub {center_dot}}, dose speed absorbed in water D{alpha}{sub {center_dot}}, and speed absorbed dose in air D{alpha}{sub {center_dot}}, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups {sigma}{sub {omega}} and that of long term by means of the standard deviation among groups {sigma}{sub {beta}}, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) {kappa}{sub {alpha}}{sub {center_dot}}, in radiation field of {sup 60}Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) D{alpha}),en radiation field of {sup 60}Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of {sup 90}Sr-{sup 90}Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases {sigma}{sub {beta}}, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of {sigma}{sub {beta}}. For example with sizes of subgroup {eta}{sub {approx}} 30 data, or with a number of subgroups {kappa}{sub {>=}}. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the

  16. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the ENEA-INMRI, Italy and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the ENEA-INMRI, Italy and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty for the comparison of 1.9 parts in 103. No significant trend with radiation quality is observed. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  17. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the LNE-LNHB, France and the BIPM in low-energy x-rays

    International Nuclear Information System (INIS)

    A key comparison has been made between the air-kerma standards of the LNE-LNHB, France and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 1.6 parts in 103, with no evidence of a trend in the results at different radiation qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  18. 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)

  19. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams; Determinacao experimental dos coeficientes de conversao de Kerma no ar para o equivalente de dose pessoal, Hp(d), e fatores de retroespalhamento em feixes de raios-x diagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves

    2008-07-01

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm{sup 3} Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with {sup 133} Ba, {sup 241} Am and {sup 57} Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of

  20. Kerma constant of gamma radiation

    International Nuclear Information System (INIS)

    The values are tabulated of the gamma kerma constant for 106 radionuclides and an energy threshold of δ=0, 10, 20 and 30 keV. The calculated values will be useful in gamma radiation protection for ease of calculation of the kerma rate from a point radiation source. The study was required in view of the consistent introduction of SI units. (author)

  1. Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the CMI, Czech Republic and the BIPM in low-energy x-rays

    Science.gov (United States)

    Burns, D. T.; Kessler, C.; Sochor, V.

    2016-01-01

    A key comparison has been made between the air-kerma standards of the CMI, Czech Republic and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at around the level of the standard uncertainty of the comparison of 3.5 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  2. Key Comparison APMP.RI(I)-K2 of air kerma standards for the CCRI reference radiation qualities for low-energy x-rays, including a supplementary comparison for the ISO 4037 narrow spectrum series

    International Nuclear Information System (INIS)

    An indirect comparison was performed between nine national standards for air kerma for the CCRI radiation qualities from 10 kV to 50 kV (APMP.RI(I)-K2) and for the ISO 4037 narrow spectrum series (15 kV and 40 kV). Among the nine institutes that participated in the comparison, seven institutes were APMP member laboratories. Three commercially available thin window parallel plate ionization chambers were used as transfer instruments and circulated among the participants. The pilot laboratory, the NMIJ/AIST, served also as the link to the corresponding BIPM.RI(I)-K2 comparison. The results show general agreement within the combined uncertainties, although certain results for Nuclear Malaysia, the BARC and the OAP show larger differences. (authors)

  3. Remarks on KERMA Factors in ACE files

    Science.gov (United States)

    Konno, C.; Ochiai, K.; Takakura, K.; Sato, S.

    2014-04-01

    Some neutron KERMA factors in ACE files are negative and extremely large if nuclear data libraries do not keep energy-balance. The status of neutron KERMA factors in the official ACE file of ENDF/B-VII.1 is examined. As a result, it is found out that neutron KERMA factors of nuclei more than 200 in ENDF/B-VII.1 have some problems. Effects of the inadequate KERMA factor are also investigated, which are large for neutron heat while those are small for total (neutron + gamma) heat. Users who use only neutron KERMA factors should check if the factors are adequate or not before they use the factors.

  4. X Ray Spectrometry of Low Energy Photons for Determining Conversion Coefficients from Air Kerma, Ka, to Personal Dose Equivalent, Hp(10), for Radiation Qualities of the ISO Narrow Spectrum Series

    International Nuclear Information System (INIS)

    The pulse height spectra of the radiation qualities N-10 to N-120 of the ISO narrow spectrum series (N) were measured using a commercial Ge spectrometer and a specially designed lead collimator. For the unfolding of these spectra, three response matrices of the Ge spectrometer for different maximum energies and energy resolutions were calculated by the EGS4 (Electron Gamma Shower version 4) code incorporating the PRESTA and LSCAT options. Then, the pulse height spectra were unfolded with two different algorithms to check the correctness. To verify the measuring and unfolding method, the first half value layers (HVLs) were determined using small ionisation chambers and the fluence spectra. The mean photon energies were calculated, also on the basis of the fluence spectra, and compared with published values. For each radiation quality N-10 to N-120 the conversion coefficients hpK(10;N,α) from air kerma Ka to personal dose equivalent at 10mm depth, Hp (10,α), were calculated for angles of incidence α of 15, 30, 45, 60 deg. and 75 deg. between the unidirectional photon field and the normal to the slab phantom surface. Because the fluence spectra were influenced by the air density, in particular the low energy spectra, the hpK(10;N,α) values were normalised to reference conditions. Differences of up to about 88% between the hpK(10;N,α) values presented in this work and those given in ISO/FDIS 4037-3 were found. (author)

  5. Environmental pressure group strength and air pollution. An empirical analysis

    International Nuclear Information System (INIS)

    There is an established theoretical and empirical case-study literature arguing that environmental pressure groups have a real impact on pollution levels. Our original contribution to this literature is to provide the first systematic quantitative test of the strength of environmental non-governmental organizations (ENGOs) on air pollution levels. We find that ENGO strength exerts a statistically significant impact on sulfur dioxide, smoke and heavy particulates concentration levels in a cross-country time-series regression analysis. This result holds true both for ordinary least squares and random-effects estimation. It is robust to controlling for the potential endogeneity of ENGO strength with the help of instrumental variables. The effect is also substantively important. Strengthening ENGOs represents an important strategy by which aid donors, foundations, international organizations and other stakeholders can try to achieve lower pollution levels around the world

  6. Comparison of air kerma-length product measurements between the PTB and the IAEA for x-radiation qualities used in computed tomography (EURAMET.RI(I)-S12, EURAMET project 1327)

    International Nuclear Information System (INIS)

    A comparison of air kerma-length product determinations for standard radiation qualities defined for use in computed tomography (CT) was performed between the PTB and the IAEA as EURAMET project 1327, registered in the KCDB as the EURAMET.RI(I)-S12 comparison. A pencil type reference-class ionization chamber of the IAEA and the three RQT beam qualities established according to the IEC standard 61627:2005 were selected for the comparison. The calibration coefficients for the transfer chamber in terms of Gy cm/C at the PTB and the IAEA using the partial irradiation method recommended in the IAEA TRS 457 were determined. The results show the calibration coefficients of both laboratories were in a very good agreement of about 0.2 % well within the estimated relative standard uncertainty of the comparison of about 0.8 %. Residual correction due to the additional aperture required for partial irradiation of pencil chambers and feasibility of the full irradiation method were also studied. (authors)

  7. Calculation of neutron kerma in tissues

    International Nuclear Information System (INIS)

    Neutron kerma of normal and tumor tissues has been calculated using the tissues elemental concentration. A program developed in Math cad contains the kerma factors of C, H, O, N, Na, Mg, P, S, Cl, K, etc. that are in normal and tumor human tissues. Having the elemental composition of any human tissue the neutron kerma can be calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic, also neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large. (Author)

  8. Calculation of neutron kerma in tissues

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E. [Unidades Academicas de Estudios Nucleares, Ing. Electrica y Matematicas, Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)]. E-mail: rvega@cantera.reduaz.mx

    2004-07-01

    Neutron kerma of normal and tumor tissues has been calculated using the tissues elemental concentration. A program developed in Math cad contains the kerma factors of C, H, O, N, Na, Mg, P, S, Cl, K, etc. that are in normal and tumor human tissues. Having the elemental composition of any human tissue the neutron kerma can be calculated. The program was tested using the elemental composition of tumor tissues such as sarcoma, melanoma, carcinoma and adenoid cystic, also neutron kerma for adipose and muscle tissue for normal adult was calculated. The results are in agreement with those published in literature. The neutron kerma for water was also calculated because in some dosimetric calculations water is used to describe normal and tumor tissues. From this comparison was found that at larger energies kerma factors are approximately the same, but energies less than 100 eV the differences are large. (Author)

  9. Comparison of the air-kerma standards of the ENEA-INMRI and the BIPM in the medium-energy X-ray range

    International Nuclear Information System (INIS)

    An indirect comparison has been made between the air erma standards of the ENEA-INMRI and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement within the stated uncertainty, although there is evidence of a trend in the results at different radiation qualities. (authors)

  10. Comparison of the air-kerma standards of the PTB and the BIPM in the medium-energy X-ray range

    International Nuclear Information System (INIS)

    An indirect comparison has been made between the air erma standards of the PTB and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the stated standard uncertainty, although the result for the 100 kV radiation quality differs significantly from that for the other qualities. (authors)

  11. Comparison of the air-kerma standards of the VNIIM and the BIPM in the low-energy X-ray range

    International Nuclear Information System (INIS)

    An indirect comparison has been made between the air erma standards of the VNIIM and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement at the level of one to two standard uncertainties. The trend in the results at different radiation qualities is explained in terms of the photon-scatter correction applied to the VNIIM standard. (authors)

  12. Computation of conversion coefficients relating air Kerma to Hp(0.07,α), Hp(10,α), and H*(10) for x-ray narrow spectrum from 40 to 140 kV

    International Nuclear Information System (INIS)

    A computation method was implemented to predict the conversion coefficients and the angular dependence factors relating air Kerma to Hp(0.07,α), Hp(10,α), and H*(10) in an ICRU slab phantom for tungsten anode x-ray spectra for tube potentials from 40 to 140 kV. The simulation of the unfiltered x-ray spectra is based on the Boone and Seibert model. The calculation of conversion coefficients were performed for an x-ray narrow spectrum at any filtration material and tube potentials in the diagnostic radiology range. This computation method has been checked for five narrow x-ray spectra using a comparison of the results with published data given by the International Organization for Standardization (ISO), and American National Standards Institute (ANSI). In all cases, the mean deviation of the calculated mean conversion coefficients values do not exceed 1% for Hp (0.07,α) and 1.5% for Hp (10,α), except at 60 deg. where a mean deviation from the ISO values of 1.72% and of 2.27% was, respectively, found. But it is still lower than the mean deviation of 2.31% for Hp(0.07,α), and of 3.08% for Hp(10,α) observed at this angle between ISO and ANSI values. Otherwise, the computed values of conversion coefficients of H*(10) differ by only 0.41% from the ISO values. The results of this computation method can be considered satisfactory considering the accuracy required in radioprotection fields, and can allow an appreciable estimation of conversion coefficients for the narrow x-ray spectra indispensable to calibrate the personnel dosimeters in terms of the personal dose equivalent

  13. Comparison of conversion coefficients for equivalent dose in terms of air kerma for photons using a male adult voxel simulator in sitting and standing posture with geometry of irradiation antero-posterior

    International Nuclear Information System (INIS)

    The dose conversion coefficient (DCC) is important to quantify and assess effective doses associated with medical, professional and public exposures. The calculation of DCCs using anthropomorphic simulators and radiation transport codes is justified since in-vivo measurement of effective dose is extremely difficult and not practical for occupational dosimetry. DCCs have been published by the ICRP using simulators in a standing posture, which is not always applicable to all exposure scenarios, providing an inaccurate dose estimation. The aim of this work was to calculate DCCs for equivalent dose in terms of air kerma (H/Kair) using the Visual Monte Carlo (VMC) code and the VOXTISS8 adult male voxel simulator in sitting and standing postures. In both postures, the simulator was irradiated by a plane source of monoenergetic photons in antero-posterior (AP) geometry. The photon energy ranged from 15 keV to 2 MeV. The DCCs for both postures were compared and the DCCs for the standing simulator were higher. For certain organs, the difference of DCCs were more significant, as in gonads (48% higher), bladder (16% higher) and colon (11% higher). As these organs are positioned in the abdominal region, the posture of the anthropomorphic simulator modifies the form in which the radiation is transported and how the energy is deposited. It was also noted that the average percentage difference of conversion coefficients was 33% for the bone marrow, 11% for the skin, 13% for the bone surface and 31% for the muscle. For other organs, the percentage difference of the DCCs for both postures was not relevant (less than 5%) due to no anatomical changes in the organs of the head, chest and upper abdomen. We can conclude that is important to obtain DCCs using different postures from those present in the scientific literature. - Highlights: • Scenarios of external photon exposures were performed in VMC code. • The VOXTISS8 simulator was irradiated in standing and sitting postures.

  14. Comparison of conversion coefficients for equivalent dose in terms of air kerma using a sitting and standing female adult voxel simulators exposure to photons in antero-posterior irradiation geometry

    International Nuclear Information System (INIS)

    Due to the difficulty in implementing invasive techniques for calculations of dose for some exposure scenarios, computational simulators have been created to represent as realistically as possible the structures of the human body and through radiation transport simulations to obtain conversion coefficients (CCs) to estimate dose. In most published papers simulators are implemented in the standing posture and this may not describe a real scenario of exposure. In this work we developed exposure scenarios in the Visual Monte Carlo (VMC) code using a female simulator in standing and sitting postures. The simulator was irradiated in the antero-posterior (AP) geometry by a plane source of monoenergetic photons with energy from 10 keV to 2 MeV. The conversion coefficients for equivalent dose in terms of air kerma (HT/Kair) were calculated for both scenarios and compared. The results show that the percentage difference of CCs for the organs of the head and thorax was not significant (less than 5%) since the anatomic position of the organs is the same in both postures. The percentage difference is more significant to the ovaries (71% for photon energy of 20 keV), to the bladder (39% at 60 keV) and to the uterus (37% at 100 keV) due to different processes of radiation interactions in the legs of the simulator when its posture is changed. For organs and tissues that are distributed throughout the entire body, such as bone (21% at 100 keV) and muscle (30% at 80 keV) the percentage difference of CCs reflects a reduction of interaction of photons with the legs of the simulator. Therefore, the calculation of conversion coefficients using simulators in the sitting posture is relevant for a more accurate dose estimation in real exposures to radiation. - Highlights: ► Scenarios of external photon exposures were performed in VMC code. ► The FAX simulator was irradiated in sitting and standing postures. ► The irradiation geometry used was the antero-posterior (AP). ► The

  15. Clinical implementation of AAPM Task Group 32 recommendations on brachytherapy source strength specification

    International Nuclear Information System (INIS)

    Historically the strength of sealed brachytherapy sources has been described by many physical quantities, including true activity, apparent activity, and equivalent mass of radium. Recently, the AAPM Task Group 32 recommended that these quantities be replaced by a single quantity, air-kerma strength, with units of μGy m2 h-1. A set of equations has been developed for unambiguously converting source strength estimates and renormalizing published dose-rate tables, which assume traditional quantities and units, into forms consistent with air-kerma strength. For commonly used brachytherapy sources, multiplicative conversion factors for each source-strength formalism and set of units are given. To convert equivalent mass of radium to air-kerma strength requires a single multiplicative factor, 7.23 μGy m2 h-1/mgRaEq, applicable to all sources. Based upon a review of vendor source specification practices, the factors for converting source strength of 198Au, 103Pd, and 125I seeds from apparent mCi to air-kerma strength are 2.06, 1.29, and 1.27 μGy m2 h-1/mCi(apparent), respectively. These factors are independent of source geometry but depend on the nominal exposure rate constant value selected by the vendor. Conversion factors applicable to mass of radium or true activity depend upon both source geometry and radionuclide identity. Because many of these conversion factors depend upon vendor choices of physical constants and exposure rate constants, readers are cautioned to carefully review vendor source strength specification practices before adopting these values clinically. Finally, the relationships between the various source strength quantities and absorbed dose rate in the medium surrounding the source are elucidated

  16. Effect of the Entrained Air Void on Strength and Interfacial Transition Zone of Air-Entrained Mortar

    Institute of Scientific and Technical Information of China (English)

    GAO Hui; ZHANG Xiong; ZHANG Yongjuan

    2015-01-01

    In order to facilitate the development and application of air entraining agents (AEA) in the high performance concrete, entrained air void structure parameters (air void size range from 10 to 1 600 μm) of 28 d sifted mortar were measured by image analysis method. The relationship between the air void size distribution and strength of mortar was studied by methods of grey connection analysis and multiple linear regression analysis. The multiple linear regression equation was established with a correlation coefifcient of 0.966. The weight of the affection of hierarchical porosity on the compressive strength ratio was also obtained. In addition, the effect of air voids on the paste-aggregate interfacial transition zone (ITZ) was analyzed by microhardness. The results show that the correlation between different pore size range and the compressive strength is negative. The effect of air void size distribution on 28 days compressive strength is different: under the condition of similar total porosity, with the increase of the porosity of the air void size, ranging from 10 to 200 μm, and the decrease of the porosity, ranging from 200 to 1 600 μm, the average air void diameter and mean free spacing are decreased; as well as the width of ITZ. On the contrary, the microhardness of the ITZ is increased while the compressive strength loss is decreased.

  17. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    Energy Technology Data Exchange (ETDEWEB)

    Carl, W. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-30

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  18. Tissue kerma vs distance relationships for initial nuclear radiation from the atomic bombs Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Initial nuclear radiation is comprised of prompt neutrons and prompt primary gamma rays from an exploding nuclear device, prompt secondary gamma rays produced by neutron interactions in the environment, and delayed neutrons and delayed fission-product gamma rays from the fireball formed after the nuclear device explodes. These various components must all be considered in establishing tissue kerma vs distance relationships which describe the decrease of initial nuclear radiation with distance in Hiroshima and Nagasaki. An interest in initial nuclear radiation at distances of as much as 2000 m from the hypocenter demands the use of discrete ordinates transport (DOT) techniques. The two-dimensional (2D) DOT-IV code developed at Oak Ridge National Laboratory (ORNL) was used to calculate the tissue kerma in an air-over-ground geometry from prompt neutrons and prompt primary gamma rays and from prompt secondary gamma rays produced in air and in soil. Data from the Los Alamos National Laboratory (LANL) were used as the source terms. The tissue kerma at ground level from delayed fission-product gamma rays and delayed neutrons, was investigated using the NUIDEA code developed by Science Applications, Inc., (SAI). This code incorporates very detailed models which can take into account such features as the immediate rise of the fireball, the rapid radioactive decay of fission-products in it, and the perturbation of the atmosphere by the explosion. Tissue kerma vs distance relationships obtained by summing results of these current state-of-the-art calculations will be discussed. Our results clearly show that the prompt secondary gamma rays and delayed fission-product gamma rays are the dominant components of the total tissue kerma from initial nuclear radiation of the atomic (or pure-fission) devices detonated over Hiroshima and Nagasaki. (author)

  19. Calibration of the indicators of the product KERMa-AREA in radiodiagnostic equipment; Calibracion de los indicadores del producto KERMA-AREA en los equipos de radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Ginjaume, M.; Jarvinen, H.; Turak, O.

    2013-07-01

    Currently the IAEA proposes two procedures for the calibration of the determination of the PKA systems integrated in the x-ray equipment. The traditional method is to measure air kerma at a certain distance from the focus through an ionization chamber reference and then the area of the field of radiation in that position. The alternative method is based on measuring directly the product kerma-area using equipment calibrated in this magnitude. In both cases the calibration procedure takes into account the position of the tube on the stretcher of the patient. The objective of this study was to compare the practical application of both calibration procedures as well as assess the accuracy of indication of the PKA in the consoles of the radiology equipment. (Author)

  20. Effects of moisture in the air on characteristics of strength in high strength spheroidal graphite cast iron

    International Nuclear Information System (INIS)

    The purpose of this study is to investigate the effects of humidity on the strength characteristics in high strength spheroidal graphite cast iron with two phases, which is ferrite and pearlite. Three spheroidal graphite cast irons (FCD400(FDI), FCD500(FPDI.82) and FCD600(FPDI.55)) were used as specimens. In addition, heat treatment (Normalizing) was conducted in FCD500 (PDI). Tensile test conforming to JIS was carried out using these resultant four materials in air and water. The specimen used was of the 14A type. The relationship between tensile strength and area ratio of brittle fracture was investigated. Fatigue crack propagation test conforming to ASTM was also carried out using these materials. Stress ratio R was 0.1, and the specimen used was of the 1CT type with a thickness of 12.5 mm. The test was carried out at room temperature and three kinds of humidity: 0, 40 and 80%. The relationship between the characteristics of fatigue crack propagation and crack closure generated on the fracture surface was investigated. Though tensile strength in FDI and FPDI.82 was not influenced by water brittlement, strength in PDI and FPDI.55, which included pearlite, was decreased by water brittlement. This phenomenon may mainly be caused by the amount of parlite in the matrix. The threshold stress intensity factor range ΔKth of all materials increased with increasing humidity. Crack closure was investigated in all materials. It seemed to become marked with increasing humidity. In the low ΔKeff region of all materials (except FPDI.55, 80%), the fatigue crack propagation rate was almost the same because of oxide-induced crack closure of the ferrite included in the matrix. In the high ΔKeff region of FPDI and PDI, the rate was not the same. The acceleration was investigated because of effect of a phenomenon similar to the water embrittlement of pearlite included in the matrix. (author)

  1. Survivor dosimetry. Part A. Fluence-to-kerma conversion coefficients

    International Nuclear Information System (INIS)

    An important step in the dosimetry evaluation is to relate the radiation passing through a unit volume of a material of interest (fluence) to the energy release (kerma) in the material, which determines the absorbed dose. The fluence-to-kerma conversion coefficients or 'kerma coefficients' used in the Dosimetry System 1986 (DS86) are taken from Kerr (1982). These kerma coefficients are based on body tissue compositions for Reference Man from the International Commission on Radiological Protection (1975) and Kerr (1982), the mass energy-absorption coefficients for photons from Hubbell (1982), and the elemental kerma coefficients for neutrons from Caswell et al. (1980). Hence, the kerma coefficients used in DS86 are approximately 20 years old. In order to provide an updated set of kerma coefficients for use in the Dosimetry System 2002 (DS02), a new evaluation has been completed. This new evaluation considered recently suggested changes in the composition of soft tissues of the body in ICRU Report 44 (International Commission on Radiation Units and Measurements 1989), the mass energy-absorption coefficients for photons by Hubbell and Seltzer (1996), and the elemental kerma coefficients for neutrons in ICRU Report 63 (International Commission on Radiation Units and Measurements 2000). The new DS02 kerma coefficients for soft tissue are presented as both point-wise data for use in Monte Carlo radiation transport calculations and multigroup data for use in discrete ordinates radiation transport calculations. (author)

  2. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy

    International Nuclear Information System (INIS)

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 ± 0.531 M Bq and kerma in air 0.03200 ± 0.00006 m Gy m/h A. (Author)

  3. Photon and neutron kerma coefficients for polymer gel dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    El-Khayatt, A.M., E-mail: Ahmed_el_khayatt@yahoo.com [Physics Department, College of Science, Al Imam Mohammad Ibn Saud Islamic University (IMSIU) (Saudi Arabia); Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, 13759 Cairo (Egypt); Vega-Carrillo, Hector Rene [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Peñuela, 98068 Zacatecas, Zac. (Mexico)

    2015-08-21

    Neutron and gamma ray kerma coefficients were calculated for 17 3D dosimeters, for the neutron and gamma ray energy ranges extend from 2.53×10{sup −8} to 29 MeV and from 1.0×10{sup −3} to 20 MeV, respectively. The calculated kermas given here for discrete energies and the kerma coefficients are referred to as “point-wise data”. Curves of gamma ray kermas showed slight dips at about 60 keV for most 3D dosimeters. Also, a noticeable departure between thermal and epithermal neutrons kerma sets for water and polymers has been observed. Finally, the obtained results could be useful for dose estimation in the studied 3D dosimeters. - Highlights: • Neutron and gamma ray kerma coefficients were calculated in 17 3D dosimeters. • Curves of gamma-ray kermas showed slight dips at about 60 keV. • Disagreement between neutron kermas for water and polymers has been observed. • The obtained results could be useful for dose estimation in the studied dosimeters.

  4. Plasma test on industrial diamond powder in hydrogen and air for fracture strength study

    Science.gov (United States)

    Chary, Rohit Asuri Sudharshana

    Diamonds are the most precious material all over the world. Ever since their discovery, the desire for natural diamonds has been great; recently, the demand has steeply increased, leading to scarcity. For example, in 2010, diamonds worth $50 billion were marketed. This increased demand has led to discovering alternative sources to replace diamonds. The diamond, being the hardest material on earth, could be replaced with no other material except another diamond. Thus, the industrial or synthetic diamond was invented. Because of extreme hardness is one of diamond's properties, diamonds are used in cutting operations. The fracture strength of diamond is one of the crucial factors that determine its life time as a cutting tool. Glow discharge is one of the techniques used for plasma formation. The glow discharge process is conducted in a vacuum chamber by ionizing gas atoms. Ions penetrate into the atomic structure, ejecting a secondary electron. The objective of this study is to determine the change in fracture strength of industrial diamond powder before and after plasma treatment. This study focuses mainly on the change in crystal defects and crushing strength (CS) of industrial diamond powder after the penetration of hydrogen gas, air and hydrogen-air mixture ions into the sample powder. For this study, an industrial diamond powder sample of 100 carats weight, along with its average fracture strength value was received from Engis Corporation, Illinois. The sample was divided into parts, each weighing 10-12 carats. At the University of Nevada, Las Vegas (UNLV), a plasma test was conducted on six sample parts for a total of 16 hours on each part. The three gas types mentioned above were used during plasma tests, with the pressure in vacuum chamber between 200 mTorr and 2 Torr. The plasma test on four sample parts was in the presence of hydrogen-air mixture. The first sample had chamber pressures between 200 mTorr and 400 mTorr. The remaining three samples had chamber

  5. Limit strength of rectangular air ventilation ducts under-seismic design condition

    International Nuclear Information System (INIS)

    The precise estimation of the limiting strength of heating, ventilating, and air conditioning ducts used in nuclear power plants is a key to the safe and economical design of the seismic supports. The formula for estimating the strength of ducts used up to this time, was derived from test results from small size ducts less than 500mm square. This data was extrapolated to obtain the strength of large ducts and therefore big margins had to be used. Consequently the seismic support spans of rectangular ducts are short and a large bulk volume of seismic support spans rectangular ducts are short and a large bulk volume of seismic support material is used in nuclear power plants. Accordingly, the authors carried out overall pure bending moment tests, shearing load tests, and local buckling load tests using large size rectangular ducts. In this paper the authors present the results of these tests and a method of designing seismic supports safely and economically by using the duct limiting strength estimation formula obtained from these tests

  6. ZZ VITAMIN-J/KERMA, Gas Production Cross-Sections, Neutron and Gamma Kerma in FOURACES Format

    International Nuclear Information System (INIS)

    1 - Description of program or function: Format: ANISN; Number of groups: 175 neutron plus 38 photon energy groups; Nuclides: H-1, D-2, T-3, Li-6, Li-7, Be-9, B-10, B-11, C, O-16, Al-27, Si, Ti, V, Cr, Mn-55, Fe, Ni, Cu, Zr, Nb-93, Mo, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, W-182, W-183, W-184, W-186, Pb, Bi-209, He-3, He-4, N-14, Mg, P-31, S, Ca, Co-59, In, Sn, Ta-181, Re Origin: EFF-1, DLC-99 (HUGO) data library; Weighting spectrum: Maxwellian plus 1/E plus fission spectrum plus fusion peak. Library of gas production cross sections, neutron kerma factors and photon kerma factors in FOURACES format according to GEFF-1 specifications. Kerma factors have been calculated for temperatures 300 K and 800 K. 2 - Method of solution: For the gas production cross sections, the lump reactions 203 and 207 included in EFF-1 had been assumed as the basic of the computation. The neutronics kerma factors have been calculated with the module KERMA of THEMIS. The photonic kerma factors have been calculated with the module GROUPG of THEMIS, starting from the DLC-99 (HUGO) data library of gamma interactions

  7. HEPA filters of high structural strength for nuclear air cleaning systems

    International Nuclear Information System (INIS)

    HEPA-filter media, though having excellent particle-removal efficiencies, remain characterized as rather brittle, fragile, and weak materials. As a result, undesired structural damage, followed by significant losses in filtration efficiency, can easily occur in handling, transport, and even normal operation of filter units. In recent years, extensive investigations into the structural limits of HEPA filters in dry air and under extended exposure to high-humidity airflow have been carried out. In the course of this work, the failure modes and the underlying failure mechanisms were thoroughly studied. On the basis of the information obtained, considerable improvements in the structural strength of HEPA filters could be achieved. As verified by removal efficiency tests, differential pressures up to 56 kPA in dry air and 15 kPA after extended operation under fog conditions were proved to be sustainable without mechanical damage to the filter medium

  8. MACK, Fluence to Kerma Generator from ENDF/B

    International Nuclear Information System (INIS)

    1 - Nature of physical problem solved: The principal purpose of the program is in calculating pointwise neutron energy release parameters (fluence-to-kerma factors) at an arbitrary energy mesh from nuclear data in ENDF/B format (2). The kerma factors are of prime importance for calculating heating and dose rates in any nuclear system. The program processes all reactions significant to energy deposition. In addition, the program calculates energy group kerma factors and group cross sections by reactions (group constants not transfer matrices) averaged over an arbitrary input weighting function or any of the 'built-in' functions. When resonance data is available, the code calculates the contribution from the resolved and unresolved resonance parameters. The pointwise cross sections, pointwise kerma factors, energy group cross sections and energy group kerma factors can be printed, punched, and/or saved on tape for all reactions and the sum as selected by input. The pointwise kerma factors can be saved for later use (3) to generate group kerma factors for a different energy group structure or possibly for inclusion in the ENDF/B evaluation for the nuclide with the appropriate MT numbers in the 300's series (2). 2 - Method of solution: The expressions for the energy release per reaction are obtained from a solution of the kinematics of nuclear reactions. The anisotropy of elastic and inelastic scattering is considered. The contribution to energy deposition from radioactive decay of the residual nucleus can be added by reaction and is calculated using Fermi theory in the case of beta decay. In the resolved resonance region, MACK accepts either single or multi level Breit-Wigner parameters. Doppler broadening is performed at an arbitrary input temperature. The unresolved resonance treatment includes some shielding effects through a 1/sigma t weighting. The energy group kerma factors and cross sections are calculated by averaging the pointwise data over either a user

  9. Analysis of numerical investigation on strength plate of airdrome outerco-veres from affect more heavy air-ship

    OpenAIRE

    А.А. Бєлятинський; Талах, С.М.

    2010-01-01

     Weight is of used for air-transport are increasing impetuously and consequently is necessary define more precisely solution on strength of airdrome strict outercoveres. In methodology is considering flan task of investigation of strength-deformation state of half-space for interaction with soil-mass.Put on task is deciding with help effective numerical method – method of finite element.Example is considering of influence on half-space of above-heavy air-transport air-ship Аn-225.Engineering ...

  10. Temperature and strain rate effects in high strength high conductivity copper alloys tested in air

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    The tensile properties of the three candidate alloys GlidCop{trademark} Al25, CuCrZr, and CuNiBe are known to be sensitive to the testing conditions such as strain rate and test temperature. This study was conducted on GlidCop Al25 (2 conditions) and Hycon 3HP (3 conditions) to ascertain the effect of test temperature and strain rate when tested in open air. The results show that the yield strength and elongation of the GlidCop Al25 alloys exhibit a strain rate dependence that increases with temperature. Both the GlidCop and the Hycon 3 HP exhibited an increase in strength as the strain rate increased, but the GlidCop alloys proved to be the most strain rate sensitive. The GlidCop failed in a ductile manner irrespective of the test conditions, however, their strength and uniform elongation decreased with increasing test temperature and the uniform elongation also decreased dramatically at the lower strain rates. The Hycon 3 HP alloys proved to be extremely sensitive to test temperature, rapidly losing their strength and ductility when the temperature increased above 250 C. As the test temperature increased and the strain rate decreased the fracture mode shifted from a ductile transgranular failure to a ductile intergranular failure with very localized ductility. This latter observation is based on the presence of dimples on the grain facets, indicating that some ductile deformation occurred near the grain boundaries. The material failed without any reduction in area at 450 C and 3.9 {times} 10{sup {minus}4} s{sup {minus}1}, and in several cases failed prematurely.

  11. Preparation and determination of kerma for Iridium 192 sources of low dose rate for brachytherapy; Preparacion y determinacion del kerma de fuentes de iridio-192 de baja tasa de dosis para braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    Tendilla, J.I.; Tovar M, V.; Mitsoura, E.; Aguilar H, F.; Alanis M, J. [Instituto Nacional de Investigaciones Nucleares, C.P. 52045-1, Salazar, Esrado de Mexico, D.F. (Mexico)

    2000-07-01

    The practice of Brachytherapy with Iridium-192 sources of low dose rate (0.4 - 0.8 Gy/h) is a technique used in the treatment of diverse illnesses. in this work the preparation, quality control and calibration are presented in terms of kerma in air of Iridium-192 using as target these recycled Iridium-Platinum wires. The targets were obtained as decayed sources of different radio therapeutical centers in the country and they were characterized by Scanning electron microscopy in order to determine their chemical composition. Subsequently it was developed an experimental design to establish the effect of neutron flux, geometrical array and irradiation time over the activity and percentage of the sources homogeneity. The homogeneity was determined by auto radiography and by Gamma spectroscopy. Once the optimal irradiation conditions were established, it is determined the apparent activity and kerma in air using a well type ionization chamber with traceability to a primary laboratory. Iridium-192 sources were obtained with an average homogeneity 96 %, apparent activity 282.129 {+-} 0.531 M Bq and kerma in air 0.03200 {+-} 0.00006 m Gy m/h A. (Author)

  12. A proper method of kerma-length product measurement during QC procedures in panoramic radiography

    International Nuclear Information System (INIS)

    As a relevant dose descriptor in panoramic radiography, product of kerma and length PKL is used. The introduction of PKL was recommended by NRPB. Anyway, NRPB termed this quantity dose-width product (DWP), the name product of kerma and length comes from a new dosimetry formalism being developed by IAEA and ICRU. The product of kerma and length in panoramic radiography is an integral of kerma profile created at a front side of the secondary collimator along a line perpendicular to the collimator. The PKL should be measured at a place of maximum intensity of the beam with respect to vertical direction. The signal is integrated over the whole exposure cycle as well. Currently, no dose descriptor in panoramic radiography is measured in the Czech Republic during the QC measurements. Therefore the measurement of PKL should be included in QC procedures as well. A pilot study using three different methods of PKL measurement is being done in the Czech Republic since 2005. The measurements are performed by an X ray film attached to the front side of a secondary collimator, by a column of thermoluminescent detectors (TLDs) and pencil ionization chamber placed perpendicular to the secondary collimator. The results obtained through the mentioned methods agree within 10% generally. The film based method has a significant disadvantage. Air kerma in a profile maximum reaches values up to 30 mGy. Standard X ray films have no dosimetric properties for such a high dose, because the response lies in a region of plateau at a characteristic curve of the film. Therefore, a primary collimator has to be covered by a shielding material. It increases energy dependence of the detection system naturally. An advantage of the film based method is knowledge of a complete kerma distribution within an X ray field. This information is used for proper positioning of a CT pencil ionization chamber or a stack of TLDs within an X ray beam. In the study, monochromatic films Foma Medix XBU (18x24 cm) and

  13. Comparison of TLD air kerma measurements in mammography

    International Nuclear Information System (INIS)

    The mammography examination is usually targeted at asymptomatic women so the narrow balance between benefit and undesirable effects is important. During the past few decades there have been significant advances in the equipment used for mammography. Even when the latest equipment and imaging systems are used, there is considerable variation from centre-to-centre in the choice of imaging parameters and techniques. There may be quite large differences in image quality and breast dose among the centres. A Co-ordinated Research Programme on 'Image quality and patient dose optimization in mammography in Eastern European Countries' was conducted by the IAEA, aiming at defining a methodology for the implementation of a quality assurance (QA) programme in mammography and at exercising the assessment of image quality and patient doses in a sample of hospitals in East European countries. Selected mammography clinics from Czech Republic, Hungary, Poland, Romania and Slovakia participate in the project. The teams consisted of experienced clinicians and physicists. They were supported by a group of experts (clinicians and medical physicists) from France, Italy and Spain. As an outcome of the project, improvements in these indicators (image quality and patient dose) after the implementation of the QA programme are expected. A comparison of dosimetry systems has been organized to assure that dosimetry measurements done in the frame of the project are comparable and traceable to the international measurement system. All five East European countries plus Spain took part in the exercise. The thermoluminescent (TL) method was selected for the comparison

  14. Estimation of graphite density and mechanical strength variation of VHTR during air-ingress accident

    International Nuclear Information System (INIS)

    An air-ingress accident in a Very High Temperature Gas-Cooled Reactor (VHTR) is anticipated to cause severe changes to graphite density and mechanical strength by an oxidation process that has many side effects. However, quantitative estimations have not yet been performed. This study focuses on predicting the changes in graphite density and mechanical strength via thermal hydraulic system analysis code. In order to analyze the change in graphite density, a simple graphite burn-off model was developed. The model is based on the similarities between a parallel electrical circuit and graphite oxidation. It was used to determine overall changes in the graphite's geometry and density. The model was validated by comparing its results to experimental data that was obtained for several temperatures. In the experiment, cylindrically shaped graphite specimens were oxidized in an electrical furnace and the variations of its mass were measured against time. The experiment's range covered temperatures between 6000 C and 9000 C. Experimental data validated the model's accuracy. Finally, the developed model along with other comprehensive graphite oxidation models was integrated into the VHTR system analysis code, GAMMA. GT-MHR 600 MWt reactor was selected as a reference reactor. Based on the calculation, the main oxidation process was observed 5.5 days after the accident when followed by natural convection. The core maximum temperature reached 16000 C, but never exceeded the maximum temperature criteria, 18000 C. However, the oxidation process did significantly decrease the density of bottom reflector, making it vulnerable to mechanical stress. The stress on the bottom reflector is greatly increased because it sustains the reactor core. The calculation proceeded until 11 days after the accident, resulting in an observed 4.5% decrease in density and a 25% reduction of mechanical strength

  15. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel.

    Directory of Open Access Journals (Sweden)

    Alireza Eshghi

    2014-12-01

    Full Text Available Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG or alumina using etch-and-rinse and self-etch adhesives.Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12. Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05. Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation.No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987. There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1. Also, decalcified or intact enamel groups had no significant difference (P=0.918. However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion.Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives.

  16. Fundamental relationships between linear energy transfer, absorbed dose, kerma, and exposure. Application to changes of mediums

    International Nuclear Information System (INIS)

    After briefly defining the quantities used in dosimetry and presenting them with a view to their simple adaptation to health physics problems, the authors establish simple mathematical relationships to express the absorbed dose, kerma and exposure in the case of electrons and photons, and also relationships between these various quantities considered in air. They then proceed to study the variations in these quantities at the interface between the air and the soft tissues of the organism and in depth in the tissues. They give the numerical values of the discontinuities liable to appear at the interface and the values obtained, relative to air, after electronic equilibrium is established in depth in the tissues. An example of application to dosimetry is also given in the case of an aluminium-walled ionization chamber. To conclude, the conditions to be fulfilled in order to make a direct measurement of the absorbed dose in the tissues are presented and discussed. (authors)

  17. Effect of Different Levels of Pressure Relieving Air-Mattress Firmness on Cough Strength

    Science.gov (United States)

    Kamikawa, Norimichi; Taito, Shunsuke; Takahashi, Makoto; Sekikawa, Kiyokazu; Hamada, Hironobu

    2016-01-01

    Cough is an important host-defense mechanism. The elderly and patients who are severely ill cannot cough effectively when lying in the supine position. Furthermore, pressure relieving air-mattresses are recommended for preventing the development of pressure ulcers. In this study, we clarified whether or not the cough peak flow (CPF), an index of cough strength, is affected by different firmness levels of a pressure relieving air-mattress in healthy volunteers in the supine position. Fifty-two healthy young men participated. All the measurements were carried out on each participant in the supine position on a pressure relieving air-mattress. The participants were assessed at two firmness levels, a “hard” and “soft” mode. The CPF, forced vital capacity (FVC), maximal expiratory pressure (PEmax), and maximal inspiratory pressure (PImax) were determined for each mode. The sinking distance of the body into the mattress was measured without any activity and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax, and PImax were determined for each mode. The sinking distance of the body into the mattress was measured and the difference between the sinking distances of the two firmness levels was determined. The CPF, FVC, PEmax and PImax values of the participants coughing on the mattress were significantly lower when the mattress was in “soft” than in “hard” mode. The differences between the sinking distances of the mattress in “soft” and “hard” modes were larger for the anterior superior iliac spine. A harder mattress may lead to increased CPF in healthy young men lying in the supine position, and increased CPF may be important for host defense. PMID:26741497

  18. Study on Strength and Ultrasonic Velocity of Air-Entrained Concrete and Plain Concrete in Cold Environment

    OpenAIRE

    Huai-shuai Shang; Ting-hua Yi; Xing-xing Guo

    2014-01-01

    Nondestructive testing technology is essential in the quality inspection of repair, alteration, and renovation of the existing engineering, especially for concrete structure in severe environment. The objective of this work is to deal with the behavior of ultrasonic velocity and mechanical properties of plain concrete and air-entrained concrete subjected to freeze-thaw cycles (F-T-C). The ultrasonic velocity and mechanical properties (tensile strength, compressive strength, cubic compressive ...

  19. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel

    OpenAIRE

    Alireza Eshghi; Maryam Khoroushi; Alireza Rezvani

    2014-01-01

    Objective: Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG) or alumina using etch-and-rinse and self-etch adhesives. Materials and Methods: Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces r...

  20. Dosimetric verification of source strength for HDR afterloading units with 192Ir- and 60Co- photon sources: comparison of three different international protocols

    International Nuclear Information System (INIS)

    Before clinical use of a brachytherapy source, regulations or recommendations by medical physics societies require an independent measurement of its air kerma strength by a qualified medical physicist. Currently, in addition to 192Ir, also HDR-60Co sources are increasingly coming into operation. However, the existing dosimetry protocols do not provide any guidelines for 60Co sources. The purpose of this work was therefore to compare air Kerma rate measurements as recommended by different dosimetry protocols for 192Ir HDR sources and to test their applicability to 60Co sources. Dosimetric verification of HDR afterloading source specification was performed according to three protocols, DIN 6809-2 (1993) in combination with DGMP-Report 13 (2006), IAEA-TECDOC-1274 (2002) and AAPM Report 41 (1993) for the nuclides 192Ir and 60Co. Measurements of the sources reference air kerma rate were performed with 3 different methods (with a cylindrical chamber both in a solid phantom and in free air, and with a well chamber) and evaluated using all three protocols for each type of source and method of measurement. The measurements with all protocols and methods show deviations from the certified specification smaller than about 1.2% for 192Ir and 2.5% for 60Co sources. The measurements with the well chamber showed the lowest deviations from the certificate value. Air kerma rate measurements for 60Co HDR sources using the existing protocols are possible with accuracy sufficient to verify source calibration as provided by the source certificate. However, extension of the protocols by correction factors for measurement with 60Co sources would be helpful. (author)

  1. Development of a calibration methodology and tests of kerma area product meters; Desenvolvimento de uma metodologia de calibracao e testes de medidores de produto Kerma-Area

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nathalia Almeida

    2013-07-01

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  2. SU-E-I-27: Estimating KERMA Area Product for CT Localizer Images

    International Nuclear Information System (INIS)

    Purpose: To estimate the free-in-air KERMA-Area Product (KAP) incident on patients due to CT localizer scans for common CT exams. Methods: In-plane beam intensity profiles were measured in localizer acquisition mode using OSLs for a 64 slice MDCT scanner (Lightspeed VCT, GE Medical Systems, Waukesha WI). The z-axis beam width was measured as a function of distance from isocenter. The beam profile and width were used to calculate a weighted average air KERMA per unit mAs as a function of intercepted x-axis beam width for objects symmetric about the localizer centerline.Patient areas were measured using manually drawn regions and divided by localizer length to determine average width. Data were collected for 50 head exams (lateral localizer only), 15 head/neck exams, 50 chest exams, and 50 abdomen/pelvis exams. Mean patient widths and acquisition techniques were used to calculate the weighted average free-in-air KERMA, which was multiplied by the patient area to estimate KAP. Results: Scan technique was 120 kV tube voltage, 10 mA current, and table speed of 10 cm/s. The mean ± standard deviation values of KAP were 120 ± 11.6, 469 ± 62.6, 518 ± 45, and 763 ± 93 mGycm2 for head, head/neck, chest, and abdomen/pelvis exams, respectively. For studies with AP and lateral localizers, the AP/lateral area ratio was 1.20, 1.33, and 1.24 for the head/neck, chest, and abdomen/pelvis exams, respectively. However, the AP/lateral KAP ratios were 1.12, 1.08, and 1.07, respectively. Conclusion: Calculation of KAP in CT localizers is complicated by the non-uniform intensity profile and z-axis beam width. KAP values are similar to those for simple radiographic exams such as a chest radiograph and represent a small fraction of the x-ray exposure at CT. However, as CT doses are reduced the localizer contribution will be a more significant fraction of the total exposure

  3. SU-E-I-27: Estimating KERMA Area Product for CT Localizer Images

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, K; Greene-Donnelly, K; Bennett, R; Thorpe, M [SUNY Upstate Medical Univ, Syracuse, NY (United States)

    2015-06-15

    Purpose: To estimate the free-in-air KERMA-Area Product (KAP) incident on patients due to CT localizer scans for common CT exams. Methods: In-plane beam intensity profiles were measured in localizer acquisition mode using OSLs for a 64 slice MDCT scanner (Lightspeed VCT, GE Medical Systems, Waukesha WI). The z-axis beam width was measured as a function of distance from isocenter. The beam profile and width were used to calculate a weighted average air KERMA per unit mAs as a function of intercepted x-axis beam width for objects symmetric about the localizer centerline.Patient areas were measured using manually drawn regions and divided by localizer length to determine average width. Data were collected for 50 head exams (lateral localizer only), 15 head/neck exams, 50 chest exams, and 50 abdomen/pelvis exams. Mean patient widths and acquisition techniques were used to calculate the weighted average free-in-air KERMA, which was multiplied by the patient area to estimate KAP. Results: Scan technique was 120 kV tube voltage, 10 mA current, and table speed of 10 cm/s. The mean ± standard deviation values of KAP were 120 ± 11.6, 469 ± 62.6, 518 ± 45, and 763 ± 93 mGycm{sup 2} for head, head/neck, chest, and abdomen/pelvis exams, respectively. For studies with AP and lateral localizers, the AP/lateral area ratio was 1.20, 1.33, and 1.24 for the head/neck, chest, and abdomen/pelvis exams, respectively. However, the AP/lateral KAP ratios were 1.12, 1.08, and 1.07, respectively. Conclusion: Calculation of KAP in CT localizers is complicated by the non-uniform intensity profile and z-axis beam width. KAP values are similar to those for simple radiographic exams such as a chest radiograph and represent a small fraction of the x-ray exposure at CT. However, as CT doses are reduced the localizer contribution will be a more significant fraction of the total exposure.

  4. Study on Strength and Ultrasonic Velocity of Air-Entrained Concrete and Plain Concrete in Cold Environment

    Directory of Open Access Journals (Sweden)

    Huai-shuai Shang

    2014-01-01

    Full Text Available Nondestructive testing technology is essential in the quality inspection of repair, alteration, and renovation of the existing engineering, especially for concrete structure in severe environment. The objective of this work is to deal with the behavior of ultrasonic velocity and mechanical properties of plain concrete and air-entrained concrete subjected to freeze-thaw cycles (F-T-C. The ultrasonic velocity and mechanical properties (tensile strength, compressive strength, cubic compressive strength, and splitting strength of C30 air-entrained concrete and plain concrete with different water-cement ratio (water-cement ratio was 0.55, 0.45, and 0.50, resp. after F-T cycles were measured. The influences of F-T cycles on ultrasonic velocity and mechanical properties of C30 air-entrained concrete and plain concrete were analyzed. And the relationship between mechanical properties and ultrasonic velocity was established. The experimental results can be useful for the design of new concrete structure, maintenance and life prediction of existing concrete structure such as offshore platform and concrete dock wall.

  5. Absorbed dose evaluation by SISCODES code, kerma and fluence deviations

    International Nuclear Information System (INIS)

    Radiotherapy is a common treatment of cancer. Radiotherapy exposes the patient to a radiation field, producing ionization, and absorbed dose. A precise dose calculation and the ability to execute the irradiation on the patient are necessary in order to avoid serious injuries on the surrounding health tissue, thus, the maximum acceptable absorbed dose error from the prescribed and applied is about 5%. The doses on radiotherapy are usually calculated by superimposition experimental dose profile, namely PDP, which is experimentally measured in a water simulator. Moreover, the radiation interaction with human body tissues depends on the chemical composition and the tissue density, which means the anthropomorphism and anthropometric of the human being. This paper evaluates the deviation of calculated value of kerma, induced by human body heterogeneities. To do this job two thorax voxel models created on SISCODES (one filled with various tissues other filled with water) were applied. The result of simulations permits two different comparisons. One is the ratio between tissues kermas and water kerma. Another is the ratio between human phantom fluence, where exists radiation scatter and reflection, and water phantom fluence. The reconstructed pictures of studied regions showing the calculated ratios, and graphs of the ratios versus energy of each tissue are shown. The dose ratio deviations obtained are, in some situations, larger than the acceptable 5% point out serious miscalculation of doses for some spatial regions on the human body. (author)

  6. Review of kerma-area product and total energy incident on patients in radiography, mammography and CT

    International Nuclear Information System (INIS)

    This study estimated the energy incident on patients in radiography, mammography and CT using data related to X-ray beam quantity and quality. The total X-ray beam quantity is the average Air Kerma multiplied by the X-ray beam area and expressed as the Kerma-Area Product (Gy cm-2). The X-ray beam quality primarily depends on the target material (and anode angle), X-ray voltage (and ripple) as well as X-ray beam filtration. For any X-ray spectra, dividing total energy (fluence x mean energy) by the X-ray beam Kerma-Area Product yields the energy per Kerma-Area Product value (ε/KAP). Published data on X-ray spectra characteristics and energy fluence per Air Kerma conversion factors were used to determine 1/KAP factors. In radiography, ε/KAP increased from 6 mJ Gy-1 cm-2 at the lowest X-ray tube voltage (50 kV) to 25 mJ Gy-1 cm-2 at the highest X-ray tube voltage (140 kV). 1/KAP values ranged between 1 and 5 mJ Gy-1 cm-2 in mammography and between 24 and 42 mJ Gy-1 cm-2 in CT. Changes in waveform ripple resulted in variations in ε/KAP of up to 15 %, similar to the effect of changes resulting in the choice of anode angle. For monoenergetic X-ray photons, there was a sigmoidal-type increase in ε/KAP from 2 mJ Gy-1 cm-2 at 20 keV to 42 mJ Gy-1 cm-2 at 80 keV. However, between 80 and 150 keV, the ε/KAP shows variations with changing photon energy of <10 %. Taking the average spectrum energy to consist of monoenergetic X rays generally overestimates the true value of ε/KAP. This study illustrated that the energy incident on a patient in any area of radiological imaging can be estimated from the total X-ray beam intensity (KAP) when X-ray beam quality is taken into account. Energy incident on the patient can be used to estimate the energy absorbed by the patient and the corresponding patient effective dose. (authors)

  7. Strength behaviour of a gas pressure sintered siliconnitride (GPSSN) under static and cyclostatic loading at 1250 C in air

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, S.; Maier, H.P. [Staatliche Materialpruefungsanstalt (MPA), Universitaet Stuttgart (Germany); Rixecker, G. [Max-Planck-Institut fuer Metallforschung, Pulvermetallurgisches Laboratorium, Stuttgart (Germany); Lohrmann, A. [Welz Industrieprodukte GmbH, Fellbach (Germany)

    2000-07-01

    The strength of ceramic materials shows commonly a great scatter. If the material exhibits distinct subcritical crack growth additionally a great scatter in lifetime occurs at least under tensile loading. Gas pressure sintered siliconnitride is expected to show a less distinct fatigue behaviour as sintered siliconnitride. Therefore, experimental investigations under dynamic, static and cyclostatic loading with 4-point bending specimens at 1250 C in air were performed. (orig.)

  8. Experimental and statistical study of the influence of broken up particles and air content on the compressive strength of concretes

    International Nuclear Information System (INIS)

    Companies in Algeria have restricted budgets devoted to the formulation of concrete. Therefore, very few research studies are interested by the concrete composition in accordance to its purpose. Hence, this work is a part of an approved research program assigned to clarify the impact of certain parameters on the quality of concrete. This experimental program consists of more than 700 cylindrical specimens of 16x32 cm that were made using local materials. Excluding the durability indicators towards the concrete, the compressive strength is the most significant property to be considered (Mounanga et al., 2006). The obtained results concern consistency and content air propertiesof the concrete at fresh state and compressive strength of hardened concrete at 28 days. Thus, the influence of the air content percentage on the concrete consistency is studied. Moreover, the influence of these two parameters on the compressive strength of the hardened concrete is also presented. The experimental results obtained constitute a data bank, which allows comparing through a statistical analysis, the model established by Feret (Baron and Ollivier, 1996) and the results of the tests. (author)

  9. Analysis of the Tandem Calibration Method for Kerma Area Product Meters Via Monte Carlo Simulations

    International Nuclear Information System (INIS)

    The IAEA recommends that uncertainties of dosimetric measurements in diagnostic radiology for risk assessment and quality assurance should be less than 7% on the confidence level of 95%. This accuracy is difficult to achieve with kerma area product (KAP) meters currently used in clinics. The reasons range from the high energy dependence of KAP meters to the wide variety of configurations in which KAP meters are used and calibrated. The tandem calibration method introduced by Poeyry, Komppa and Kosunen in 2005 has the potential to make the calibration procedure simpler and more accurate compared to the traditional beam-area method. In this method, two positions of the reference KAP meter are of interest: (a) a position close to the field KAP meter and (b) a position 20 cm above the couch. In the close position, the distance between the two KAP meters should be at least 30 cm to reduce the effect of back scatter. For the other position, which is recommended for the beam-area calibration method, the distance of 70 cm between the KAP meters was used in this study. The aim of this work was to complement existing experimental data comparing the two configurations with Monte Carlo (MC) simulations. In a geometry consisting of a simplified model of the VacuTec 70157 type KAP meter, the MCNP code was used to simulate the kerma area product, PKA, for the two (close and distant) reference planes. It was found that PKA values for the tube voltage of 40 kV were about 2.5% lower for the distant plane than for the close one. For higher tube voltages, the difference was smaller. The difference was mainly caused by attenuation of the X ray beam in air. Since the problem with high uncertainties in PKA measurements is also caused by the current design of X ray machines, possible solutions are discussed. (author)

  10. Development of a calibration methodology and tests of kerma area product meters

    International Nuclear Information System (INIS)

    The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient's skin doesn't exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter. (author)

  11. Switching Impulse Strength of ±800 kV UHVDC Transmission Line Air Gap Insulation Under High Altitude Condition

    Institute of Scientific and Technical Information of China (English)

    LIAO Yongli; GAO Chao; LI Ruihai; WANG Guoli; MA Yi

    2012-01-01

    This paper is concerning switching impulse air gap insulation characteristics of rod-to-plane and V-string 6-conductor bundle to tower body in ±800 kV transmission lines. The tests were performed in China Southern Power Grid Co. , Ltd. (CSG) Kunming outdoor UHV laboratory at an altitude of 2 100 m. The switching impulse strength performance were obtained at a rod to-plane arrangement and a full-scale model of 6-conductor bundle to tower. The test gap length of the typical rod-to-plane arrangement is 1.5~10 m and 5.3~8.2 m for the conductor-tower model, and the range of test voltage is about 450~3 100 kV. The critical positive switching impulse strength of conductor tower gap is 1 525 kV in the gap length of 6.2 m. Additionally, the influence of the wave front time (100~1 700 gs) on the 50% flashover voltage is discussed. According to the test data, the minimum air gap clearances of the conductor-tower model with V-insulators at the altitude of 2 100 m should be longer than 6.8 m (wave front time 250 μs) and 5. 8 m (wave front time 1 000 μs), respectively. The results are useful to air gap insulation design in UHVDC systems with rated voltage of ±800 kV.

  12. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    Science.gov (United States)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm-2 for both very high and very low charged-particle transport cut

  13. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

    Science.gov (United States)

    Blatz, Markus B; Phark, Jin-Ho; Ozer, Fusun; Mante, Francis K; Saleh, Najeed; Bergler, Michael; Sadan, Avishai

    2010-04-01

    This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions. PMID:19415350

  14. A tough, thermally conductive silicon carbide composite with high strength up to 1600 degreesC in Air

    Science.gov (United States)

    Ishikawa; Kajii; Matsunaga; Hogami; Kohtoku; Nagasawa

    1998-11-13

    A sintered silicon carbide fiber-bonded ceramic, which consists of a highly ordered, close-packed structure of very fine hexagonal columnar fibers with a thin interfacial carbon layer between fibers, was synthesized by hot-pressing plied sheets of an amorphous silicon-aluminum-carbon-oxygen fiber prepared from an organosilicon polymer. The interior of the fiber element was composed of sintered beta-silicon carbide crystal without an obvious second phase at the grain boundary and triple points. This material showed high strength (over 600 megapascals in longitudinal direction), fibrous fracture behavior, excellent high-temperature properties (up to 1600 degreesC in air), and high thermal conductivity (even at temperatures over 1000 degreesC). PMID:9812889

  15. Experimental determination of kerma factors at E/sub n/ approx. = 15 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, E.; Slaughter, D.R.; Howell, R.H.

    1978-04-05

    Experimental values for the kerma per unit fluence at the neutron energy, E/sub n/ = 15 MeV, have been determined for graphite, Mg, and Fe. Ion chambers of small size with walls of these materials were employed, and were filled with a variety of gases--N/sub 2/, CO/sub 2/, Ne, Ar, Kr, and Xe. A calibrated neutron source was employed, allowing a straightforward determination of the kerma per unit fluence.

  16. Influence of Air Abrasion and Sonic Technique on Microtensile Bond Strength of One-Step Self-Etch Adhesive on Human Dentin

    Directory of Open Access Journals (Sweden)

    Baraba Anja

    2015-01-01

    Full Text Available The purpose of this in vitro study was to evaluate the microtensile bond strength of one-step self-etch adhesive to human dentin surface modified with air abrasion and sonic technique and to assess the morphological characteristics of the pretreated dentin surface. The occlusal enamel was removed to obtain a flat dentin surface for thirty-six human molar teeth. The teeth were randomly divided into three experimental groups (n = 12 per group, according to the pretreatment of the dentin: (1 control group, (2 air abrasion group, and (3 sonic preparation group. Microtensile bond strength test was performed on a universal testing machine. Two specimens from each experimental group were subjected to SEM examination. There was no statistically significant difference in bond strength between the three experimental groups (P > 0.05. Mean microtensile bond strength (MPa values were 35.3 ± 12.8 for control group, 35.8 ± 13.5 for air abrasion group, and 37.7 ± 12.0 for sonic preparation group. The use of air abrasion and sonic preparation with one-step self-etch adhesive does not appear to enhance or impair microtensile bond strength in dentin.

  17. Humidity dependence in kerma area product meter used in diagnostic X ray examinations

    International Nuclear Information System (INIS)

    The air-kerma area product, PKA, is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. PKA has the unit Gym2 and can be directly measured by use of a Kerma Area Product (KAP) meter placed in the radiation beam. PKA is the recommended quantity for use in the establishment of diagnostic reference levels (DRLs) for conventional x-ray examinations and is also a good indicator for when threshold doses for deterministic effects are reached in interventional x-ray procedures. Most modern x-ray equipment provides the operator with the total PKA from the examination or procedure. This PKA is either obtained from PKA measurements from a built-in KAP meter or calculated from exposure parameters. To get a reliable estimate of DRLs and the patient dose, it is essential that the PKA measurement is correct. Thus all environmental influences on the KAP meter should be taken into account. These influences can either be corrected for or included in the measurement uncertainty. These have to be considered both in the calibration of the KAP-meters, in the use of the KAP meters and in the determination of DRLs. A KAP meter is an electrometer and a plane parallel ion chamber with an active area of typical 15 cm X 15 cm. The KAP meter usually consist of three plastic plates (PMMA) which is coated with a conducting layer made of indium oxide doped with tin (In2O3:Sn). This coating is used due to its transparency to light. The air layers between the plates (sensitive volume) are open to the air. Thus the readings from the KAP meter have to be corrected for air pressure and temperature as for other ion chambers. It has been assumed that the humidity dependence of the KAP meter is so small that no correction has been necessary. This work will show that KAP meter with PMMA plastic plates coated with In2O3:Sn shows a humidity dependence so large that corrections should be considered. The measurements

  18. Estimation of distance error by fuzzy set theory required for strength determination of HDR 192Ir brachytherapy sources

    International Nuclear Information System (INIS)

    Verification of the strength of high dose rate (HDR) 192Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm3 is one of the recommended methods for measuring RAKR of HDR 192Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR 192Ir source strength measurement. (author)

  19. Estimation of distance error by fuzzy set theory required for strength determination of HDR (192)Ir brachytherapy sources.

    Science.gov (United States)

    Kumar, Sudhir; Datta, D; Sharma, S D; Chourasiya, G; Babu, D A R; Sharma, D N

    2014-04-01

    Verification of the strength of high dose rate (HDR) (192)Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm(3) is one of the recommended methods for measuring RAKR of HDR (192)Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR (192)Ir source strength measurement. PMID:24872605

  20. Estimation of distance error by fuzzy set theory required for strength determination of HDR 192Ir brachytherapy sources

    Science.gov (United States)

    Kumar, Sudhir; Datta, D.; Sharma, S. D.; Chourasiya, G.; Babu, D. A. R.; Sharma, D. N.

    2014-01-01

    Verification of the strength of high dose rate (HDR) 192Ir brachytherapy sources on receipt from the vendor is an important component of institutional quality assurance program. Either reference air-kerma rate (RAKR) or air-kerma strength (AKS) is the recommended quantity to specify the strength of gamma-emitting brachytherapy sources. The use of Farmer-type cylindrical ionization chamber of sensitive volume 0.6 cm3 is one of the recommended methods for measuring RAKR of HDR 192Ir brachytherapy sources. While using the cylindrical chamber method, it is required to determine the positioning error of the ionization chamber with respect to the source which is called the distance error. An attempt has been made to apply the fuzzy set theory to estimate the subjective uncertainty associated with the distance error. A simplified approach of applying this fuzzy set theory has been proposed in the quantification of uncertainty associated with the distance error. In order to express the uncertainty in the framework of fuzzy sets, the uncertainty index was estimated and was found to be within 2.5%, which further indicates that the possibility of error in measuring such distance may be of this order. It is observed that the relative distance li estimated by analytical method and fuzzy set theoretic approach are consistent with each other. The crisp values of li estimated using analytical method lie within the bounds computed using fuzzy set theory. This indicates that li values estimated using analytical methods are within 2.5% uncertainty. This value of uncertainty in distance measurement should be incorporated in the uncertainty budget, while estimating the expanded uncertainty in HDR 192Ir source strength measurement. PMID:24872605

  1. Development of glass-fiber high-efficiency particulate air filters of high structural strength on the basis of the establishment of failure mechanisms

    International Nuclear Information System (INIS)

    Practical experience from routine operation in nuclear installations as well as extensive bench and laboratory testing proved the structural limits of HEPA filters to be very low thus demonstrating the need for improvement of their structural strength. Detailed analysis of the courses and modes of filter failure under the challenge of dry air at high velocities and ambient temperature, together with additional measurements, allowed the establishment of the dominating mechanisms of filter failure. Based on this information, the following three options for effective and economical improvements in filter structural limits exist: (1) an increase in the tensile strength of the filter medium; (2) an increase in the stability of the pack to prevent the swelling of individual pleats; and (3) an increase in the area moment of inertia of the separators and a decrease in the sharpness of their edges. By using a reinforced glass fiber filter medium, the structural strength of standard size HEPA filters was increased to 31 kPa with dry air and beyond 10 kPa with air at high humidity. Prototype filters built with standard glass-fiber media and separators with inclined corrugations exhibited failure pressures of approximately 50 kPa under high velocity airflows. The combination of both types of improvements, together with other measures, will soon lead to even higher HEPA-filter structural strength

  2. Interlaminar shear strength of SiC matrix composites reinforced by continuous fibers at 900 °C in air

    International Nuclear Information System (INIS)

    Highlights: • The application of SiC fiber could improve ILSS of the SiC matrix composites. • The orientation of the warp fibers plays a critical role in determining ILSS of 2.5D-C/SiC. • The failure mechanisms of 2D composites involve matrix cracking, and interfacial debonding. - Abstract: To reveal the shear properties of SiC matrix composites, interlaminar shear strength (ILSS) of three kinds of silicon carbide matrix composites was investigated by compression of the double notched shear specimen (DNS) at 900 °C in air. The investigated composites included a woven plain carbon fiber reinforced silicon carbide composite (2D-C/SiC), a two-and-a-half-dimensional carbon fiber-reinforced silicon carbide composite (2.5D-C/SiC) and a woven plain silicon carbon fiber reinforced silicon carbide composite (2D-SiC/SiC). A scanning electron microscope was employed to observe the microstructure and fracture morphologies. It can be found that the fiber type and reinforcement architecture have significant impacts on the ILSS of the SiC matrix composites. Great anisotropy of ILSS can be found for 2.5D-C/SiC because of the different fracture resistance of the warp fibers. Larger ILSS can be obtained when the specimens was loaded along the weft direction. In addition, the SiC fibers could enhance the ILSS, compared with carbon fibers. The improvement is attributed to the higher oxidation resistance of SiC fibers and the similar thermal expansion coefficients between the matrix and the fibers

  3. Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

    Directory of Open Access Journals (Sweden)

    ARAO Nobuaki

    2015-12-01

    Full Text Available ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS and Block HC (BHC] were pretreated as follows: (a no treatment (None, (b application of a ceramic primer (CP, (c alumina-blasting at 0.2 MPa (AB, (d AB followed by CP (AB+CP, and (e glass-beads blasting at 0.4 MPa (GBB followed by CP (GBB+CP. The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS and ResiCem (RC]. The bond strengths after 24 h (TC 0 and after thermal cycling (TC 10,000 at 4–60°C were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05. Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p0.05. The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05, but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05. Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP.

  4. Impact of heat load location and strength on air flow pattern with a passive chilled beam system

    Energy Technology Data Exchange (ETDEWEB)

    Kosonen, Risto [Halton Oy, Niittyvillankuja 4, 01510 Vantaa (Finland); Saarinen, Pekka; Koskela, Hannu [Finnish Institute of Occupational Health, Lemminkaisenkatu 14-18 B, 20520 Turku (Finland); Hole, Alex [Arup, Rob Leslie-Carter, Level 10, 201 Kent Street, Sydney, NSW 2000 (Australia)

    2010-01-15

    A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25 m/s with the extremely high heat gain of 164 W/m{sup 2}. The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space. (author)

  5. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    XCom program. The significant variation of Z(eff) and N-el is due to the variations in the dominance of different interaction processes in different energy regions. The maximum values of Z(eff) and N-el are found in the low-energy range, where photoelectric absorption is the main interaction process. The...... also made with the single values of the Z(eff) and N-el provided by the program XMuDat. It is also observed that carbohydrates have a larger kerma than fatty acids in the low-energy region, where photoelectric absorption dominates. In contrast, fatty acids have a larger kerma than carbohydrates in the...

  6. Studies on mass attenuation coefficient, mass energy absorption coefficient and kerma of some vitamins

    International Nuclear Information System (INIS)

    Highlights: ► Kerma is essential for nuclear medicine, diagnostics and radiation dosimeter. ► The values of μm and μe/ρ depends on the photon energy and chemical content of vitamins. ► New experiments should be performed to study physical parameters of biomolecules. -- Abstract: The mass attenuation coefficients for some vitamins (retinol, beta-carotene, thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, biotin, folic acid, cyanocobalamin, ascorbic acid, cholecalciferol, alpha-tocopherol, ketamine, hesperidin) were determined experimentally and theoretically at 356.61, 661.66, 1250 and 1408.01 keV photon energies by using a NaI(Tl) scintillation detector. Also, the mass energy absorption coefficients and kerma have been calculated. The calculated values were compared with the semi-empirical values for vitamins.

  7. Calculated neutron KERMA factors based on the LLNL ENDL data file. Volume 27

    International Nuclear Information System (INIS)

    Neutron KERMA factors calculated from the LLNL ENDL data file are tabulated for 15 composite materials and for the isotopes or elements in the ENDL file from Z = 1 to Z = 29. The incident neutron energies range from 1.882 x 10-5 to 20. MeV for the composite materials and from 1.30 x 10-9 to 20. MeV for the isotopes and elements

  8. A simple device for the measurement of kerma based on commercial PIN photo diodes

    Czech Academy of Sciences Publication Activity Database

    Kushpil, Vasilij; Kushpil, Svetlana; Huňa, Zdeněk

    Cedex: EDP Sciences, 2012, s. 1-9. ISBN 978-88-7438-069-5. ISSN 2100-014X. [International Conference on Environmental Radioactivity - New Frontiers and Developments. Řím (IT), 25.10.2010-27.10.2010] R&D Projects: GA MŠk LC07048 Institutional support: RVO:61389005 Keywords : PIN diode * kerma measurement Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  9. Quantifying the clear-sky temperature inversion frequency and strength over the Arctic Ocean during summer and winter seasons from AIRS profiles

    Directory of Open Access Journals (Sweden)

    A. Devasthale

    2010-02-01

    Full Text Available Temperature inversions are one of the dominant features of the Arctic atmosphere and play a crucial role in various processes by controlling the transfer of mass and moisture fluxes through the lower troposphere. It is therefore essential that they are accurately quantified, monitored and simulated as realistically as possible over the Arctic regions. In the present study, the characteristics of inversions in terms of frequency and strength are quantified for the entire Arctic Ocean for summer and winter seasons of 2003 to 2008 using the AIRS data for the clear-sky conditions. The probability density functions (PDFs of the inversion strength are also presented for every summer and winter month.

    Our analysis shows that although the inversion frequency along the coastal regions of Arctic decreases from June to August, inversions are still seen in almost each profile retrieved over the inner Arctic region. In winter, inversions are ubiquitous and are also present in every profile analysed over the inner Arctic region. When averaged over the entire study area (70° N–90° N, the inversion frequency in summer ranges from 69% to 86% for the ascending passes and 72% to 86% for the descending passes. For winter, the frequency values are 88% to 91% for the ascending passes and 89% to 92% for the descending passes of AIRS/AQUA. The PDFs of inversion strength for the summer months are narrow and right-skewed (or positively skewed, while in winter, they are much broader. In summer months, the mean values of inversion strength for the entire study area range from 2.5 K to 3.9 K, while in winter, they range from 7.8 K to 8.9 K. The standard deviation of the inversion strength is double in winter compared to summer. The inversions in the summer months of 2007 were very strong compared to other years. The warming in the troposphere of about 1.5 K to 3.0 K vertically extending up to 400 hPa was observed in the summer months of 2007.

  10. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    International Nuclear Information System (INIS)

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of 125I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for 125I selectSeedTM brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and changes in the

  11. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel [Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Cecilio, E-18012 Granada (Spain); Perez-Calatayud, Jose [Servicio de Radioterapia, Unidad de Radiofísica, Hospital Universitario y Politécnico La Fe, E-46026 Valencia (Spain); Simancas, Fernando; Lallena, Antonio M. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Gazdic-Santic, Maja [Department of Medical Physics and Radiation Safety, Clinical Centre of Sarajevo University, 71000 Sarajevo (Bosnia and Herzegovina)

    2013-12-15

    Purpose: Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is corrected to standard atmospheric conditions using the usual temperature and pressure correction factor. Nevertheless, when assessing low energy sources, the ionization chambers may not fulfill that condition and a residual density dependence still remains after correction. In this work, the authors examined the behavior of the PTW 34051 SourceCheck ionization chamber when measuring the air kerma strength of {sup 125}I seeds.Methods: Four different SourceCheck chambers were analyzed. With each one of them, two series of measurements of the air kerma strength for {sup 125}I selectSeed{sup TM} brachytherapy sources were performed inside a pressure chamber and varying the pressure in a range from 747 to 1040 hPa (560 to 780 mm Hg). The temperature and relative humidity were kept basically constant. An analogous experiment was performed by taking measurements at different altitudes above sea level.Results: Contrary to other well-known ionization chambers, like the HDR1000 PLUS, in which the temperature-pressure correction factor overcorrects the measurements, in the SourceCheck ionization chamber they are undercorrected. At a typical atmospheric situation of 933 hPa (700 mm Hg) and 20 °C, this undercorrection turns out to be 1.5%. Corrected measurements show a residual linear dependence on the density and, as a consequence, an additional density dependent correction must be applied. The slope of this residual linear density dependence is different for each SourceCheck chamber investigated. The results obtained by taking measurements at different altitudes are compatible with those obtained with the pressure chamber.Conclusions: Variations of the altitude and

  12. Doses monitoring in radiology: calibration of air kerma-area product (PKA meters

    Directory of Open Access Journals (Sweden)

    Ricardo Andrade Terini

    2013-12-01

    Full Text Available Objective The authors have sought to study the calibration of a clinical PKA meter (Diamentor E2 and a calibrator for clinical meters (PDC in the Laboratory of Ionizing Radiation Metrology at Instituto de Energia e Ambiente - Universidade de São Paulo. Materials and Methods Different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm3 cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results The lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion The calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0% than with the use of the monitor chamber (3.5% as a reference.

  13. A design of brachytherapy source calibration template for air kerma rate/activity measurement

    International Nuclear Information System (INIS)

    This simple template can be used for the purpose of calibration of brachytherapy source, if the department does not have the calibration-track stand. One can design this template in the hospital itself as per the requirement, availability and facility, and the expenses also will be less. It is fully made up of a very thin 0.75 mm thickness of paper cardboard and this is the speciality. Currently this template is being utilized for accurate and easy calibration purposes

  14. Verification of traceability and backscattering in surface entrance air kerma measurements with detector type ionizing chamber

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, G.J.; Peixoto, J.G.P., E-mail: guilherm@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    Measurements of doses in radiology services by ionizing chambers are easier than those made by TLD, however the protocols for measurements differ regarding the calibration. The objectives were to verify the traceability in the measures of ESAK corrected by the inverse square law, due to the difference in position between the source and IC and the influence of the backscattered radiation in bringing the detector to the table. Was defined a procedure practiced by the radiological services and designed experimental arrangements for the same technique. Was noted that the approximation of the detector to the table generated a significant backscattered. (author)

  15. An EGSnrc investigation of cavity theory for ion chambers measuring air kerma

    International Nuclear Information System (INIS)

    The EGSnrc system is used to compare the response of an aluminum-walled thimble chamber to that of a graphite-walled thimble chamber for a 60Co beam. When compared to previous experimental results, the EGSnrc values of the ratios of chamber response differ by as much as 0.7% from the experiment. However, it is shown that this difference can be more than accounted for by switching from using the graphite mean excitation energy of 78 eV used in dosimetry protocols to the value of 86.8 eV suggested by more recent stopping-power experiments. This suggests that the uncertainty analysis of Monte Carlo results must be done more carefully, by taking into account uncertainties in the underlying basic data such as the electron and photon cross sections. In comparison to Spencer-Attix cavity theory for a thick-walled ion chamber, the Monte Carlo calculated values of the chamber response differ from the expected ones by 0.15% and 0.01% for the graphite and aluminum chambers, respectively, which are comparable to previously reported values for the Spencer-Attix correction factors. EGSnrc is also used to investigate the effect on the chamber response of thin dag layers on the inside of the aluminum wall. There is good agreement between the calculated and measured changes in chamber response versus the thickness of the dag. The results are compared to the predictions of the Almond-Svensson extension of cavity theory and show that the theory does not correctly predict the chamber response in the presence of thin dag layers. This finding is in agreement with previously reported experimental results. It is demonstrated that the values of α, the fraction of ionizations in the gas arising from electrons generated in the dag layer, used in the theory, are not the source of the disagreement

  16. Calibration of dosimeters used in diagnostic radiology in terms of air kerma rate

    International Nuclear Information System (INIS)

    This study was performed to determine IEC reference radiation beam quality for calibrating dosimeters used in diagnostic radiology. Additional filtration required to establish certain IEC quality was estimated from beam transmission measurements using Al absorbers. The experiment was carried out using medical x-ray equipment at Neelain Medical Center, Khartoum. The required added filtration thickness required to establish RQA quality was estimated according to the the method described in the IEC standard. The required filtration was estimated for each of radiation quality (40, 60, 80, 100, 120,) kV. Result showed the maximum deviation of 2.3%, for the half value-layers, which complied with the standard requirement of 3%, the additional filtration required for the RQA qualities was found to as follows: 1.2 mmAL (RQA2, 40 kV), 11.0 mmAL (RQA3, 60 kV), 20.7 mmAL ( RQA4, 80 kV), 29.5 mmAL (RQA5, 100 kV) and 33.0 mmAL (AQA6, 120 kV), those qualities recommended to be applied to calibration of the diagnostic radiology measurements instruments in Sudan.(Author)

  17. Air

    Science.gov (United States)

    ... house) Industrial emissions (like smoke and chemicals from factories) Household cleaners (spray cleaners, air fresheners) Car emissions (like carbon monoxide) *All of these things make up “particle pollution.” They mostly come from cars, trucks, buses, and ...

  18. Assessment of the Effects of Flow Rate and Ionic Strength on the Performance of an Air-Cathode Microbial Fuel Cell Using Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Doug Aaron

    2010-03-01

    Full Text Available Impedance changes of the anode, cathode and solution were examined for an air-cathode microbial fuel cell (MFC under varying conditions. An MFC inoculated with a pre-enriched microbial culture resulted in a startup time of less than ten days. Over this period, the anode impedance decreased below the cathode impedance, suggesting a cathode-limited power output. Increasing the anode flow rate did not impact the anode impedance significantly, but it decreased the cathode impedance by 65%. Increasing the anode-medium ionic strength also decreased the cathode impedance. These impedance results provide insight into electron and proton transport mechanisms and can be used to improve MFC performance.

  19. Air

    International Nuclear Information System (INIS)

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  20. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources

    International Nuclear Information System (INIS)

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 106 n/s-μg and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for En > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with En > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of 252Cf, to optimize and to individualize the patients treatments. (Author)

  1. KAOS-V code: An evaluation tool for neutron kerma factors and other nuclear responses

    International Nuclear Information System (INIS)

    The accurate evaluation of neutron fluence-to-kerma factors from microscopic nuclear data is the subject of this report. The algorithms developed for this purpose combine in a consistent manner the two basic methods for computing kerma factors, namely kinematics and direct energy balance. These algorithms are implemented in the code KAOS-V which was used as the main evaluation tool to construct the response function library KAOS/LIB-V. KAOS-V uses data from the evaluated nuclear data files ENDF/B/V. Auxiliary nuclear data bases, e.g., the Japanese evaluated nuclear data library JENDL-2 can be used as a source of isotopic cross sections when these data are not provided in ENDF/B-V files for a natural element. These are needed mainly to estimate average quantities such as effective Q-values for the natural element. The code has the ability to compare the different results which aids in the choice of a consistent set of algorithms to evaluate kerma factors. Data in ENDF/B-IV and ENDF/B-V format can be processed. For resonance treatment, the code has the ability to access NJOY and NPTXS interface files in formatted or binary forms. No input instructions are necessary to run the code interactively. The user can simply respond to the interactive messages sent by the code if an INPUT file is absent. An INPUT file is automatically generated following an interactive run, and can be edited and used to rerun or produce different results. Grouped and point output data can be produced along with graphic representation. These features are instrumental in detecting and understanding energy balance deficiencies and other problems in the nuclear data files. 60 refs., 4 figs

  2. Determination of the kerma factors for 14-MeV neutrons in TEP, C, Mg, and Fe

    International Nuclear Information System (INIS)

    Kerma factors, defined as kerma per unit neutron fluence, for 14 MeV D-T neutrons in tissue equivalent plastic, C, Mg and Fe were determined in this work. Rossi-type TEP, C, Mg and Fe walled proportional counters filled with propane-based tissue-equivalent gas and Ar gas at low pressure were employed to measure the energy deposition in the counters. Based upon the concept of Crossers, Insiders, Starters and Stoppers (CISS) developed by Caswell, a theoretical model was used for the analysis of energy deposition in spherical detectors. Because of the detailed analyses the uncertainties in the kerma factors as obtained in this work are evaluated to be between 8 to 11% which are significantly lower than those reported previously for experimental measurements

  3. Scattering study at free air ionization chamber diaphragm

    International Nuclear Information System (INIS)

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are kRQR-M1=0,9946, kRQR-M2=0,9932, kRQR-M3=0,9978 and kRQR-M4=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  4. ZZ RFL-2-DTF, Group Constant Library of Reaction Cross-Section, Gas Production, Kerma, DPA

    International Nuclear Information System (INIS)

    1 - Description of program or function: Format: DTF format and the structure is adopted from the MACKLIB-IV library. Number of groups: group library of reaction cross sections, gas production, kerma and DPA. Materials: H-1, H-2, H-3, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-Nat, Al-27, Si-28, P-31, S-Nat, Cl-Nat, Ar-36, Ar-38, Ar-40, K-Nat, Ca-Nat, Ti-Nat, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Zr-Nat, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-100, Ag-107, Ag-109, Cd-Nat, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-12,2 Sn-124, Ba-130, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Hf-174, Hf-176, Hf-177, Hf- 178, Hf-179, Hf-180, Ta-181, W-Nat, W-182, W-183, W-184, W-186, Re-185, Re-187, Pb-Nat, Bi-209. Temperatures: T=293.6 K. Origin: GEFF-2 and GEPDL. RFL-2 is a group library of reaction cross sections, gas production, kerma and DPA based upon GEFF-2 and GEPDL - which are included in the package ZZ-GEFF-2-GENDF - and upon DECNET - included in the ZZ-DECNET-GENDF package (see below the description of these libraries). RFL-2 has been derived from them by the GENTORFL code (GENdf To RFL). Its primary use is to complete the neutron transport libraries in ANISN or FIDO format with data normally not present in the traditional files. It includes all GEFF-2 materials at T=293.6 K and σ0 = infinity; as qualifying point it gives 'delayed' kerma and 'delayed' gamma-ray production matrices, i.e. the energy release and the photons, respectively, generated by the decay of radioactive nuclei produced in the primary reactions; decay events that occur within 10000 seconds from the primary reaction are taken into account. The library includes many isotopes, since for each natural element included in GEFF-2 the decay of all component isotopes have been traced out. The library is in DTF format and the structure is

  5. Enhanced ozone strongly reduces carbon sink strength of adult beech (Fagus sylvatica) - Resume from the free-air fumigation study at Kranzberg Forest

    International Nuclear Information System (INIS)

    Ground-level ozone (O3) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O3-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O3 exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O3 levels. Elevated O3 significantly weakened the C sink strength of the tree-soil system as evidenced by lowered photosynthesis and 44% reduction in whole-stem growth, but increased soil respiration. Associated effects in leaves and roots at the gene, cell and organ level varied from year to year, with drought being a crucial determinant of O3 responsiveness. Regarding adult individuals of a late-successional tree species, empirical proof is provided first time in relation to recent modelling predictions that enhanced ground-level O3 can substantially mitigate the C sequestration of forests in view of climate change. - Empirical proof corroborates substantial mitigation of carbon sequestration in the tree-soil system of a forest site under enhanced O3 impact for adult beech.

  6. Tissue kerma vs distance relationships for initial nuclear radiation from the atomic devices detonated over Hiroshima and Nagasaki

    International Nuclear Information System (INIS)

    Initial nuclear radiation is comprised of prompt neutrons and prompt primary gammas from an exploding nuclear device, prompt secondary gammas produced by neutron interactions in the environment, and delayed neutrons and delayed fission-product gammas from the fireball formed after the nuclear device explodes. These various components must all be considered in establishing tissue kerma vs distance relationships which describe the decrease of initial nuclear radiation with distance in Hiroshima and in Nagasaki. The tissue kerma at ground evel from delayed fission-product gammas and delayed neutrons was investigated using the NUIDEA code developed by Science Applications, Inc. This code incorporates very detailed models which can take into account such features as the rise of the fireball, the rapid radioactive decay of fission products in it, and the perturbation of the atmosphere by the explosion. Tissue kerma vs distance relationships obtained by summing results of these current state-of-the-art calculations will be discussed. Our results clearly show that the prompt secondary gammas and delayed fission-product gammas are the dominant components of total tissue kerma from initial nuclear radiation in the cases of the atomic (or pure-fission) devices detonated over Hiroshima and Nagasaki

  7. Effective atomic number, electron density and kerma of gamma radiation for oxides of lanthanides

    Indian Academy of Sciences (India)

    R S Niranjan; B Rudraswamy; N Dhananjaya

    2012-03-01

    An attempt has been made to estimate the effective atomic number, electron density (0.001 to 105 MeV) and kerma (0.001 to 20 MeV) of gamma radiation for a wide range of oxides of lanthanides using mass attenuation coefficient from WinXCom and mass energy absorption coefficient from Hubbell and Seltzer. The values of these parameters have been found to change with energy for different oxides of lanthanides. The lanthanide oxides find remarkable applications in the field of medicine, biology, nuclear engineering and space technology. Nano-oxides of lanthanide find applications in display and lighting industry.

  8. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil

    International Nuclear Information System (INIS)

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  9. Audit on source strength determination for HDR and PDR 192Ir brachytherapy in Sweden

    International Nuclear Information System (INIS)

    Background and purpose: To investigate the status of source strength determination in terms of reference air kerma rate (RAKR) for HDR and PDR 192Ir brachytherapy in Sweden. Materials and methods: RAKR was determined in each of the 14 Swedish afterloaders, using calibrated equipment from the Swedish Secondary Standard Dosimetry Laboratory. Results: Values of RAKR from the external audit, the hospitals and vendors agreed within the uncertainty limits guaranteed by the vendors. Conclusions: The accuracy in RAKR determination has increased over the last years as a result of increased availability of interpolation standards for HDR 192Ir and the increased use of robust well-type ion chambers designed for brachytherapy. It is recommended to establish a ratio between the RAKR value from own measurements at the hospital and that of the vendor since such a ratio embeds constant systematic differences due to e.g. varying traceability and therefore has the potential of being less uncertain than the RAKR alone. Traceability to primary standards for HDR 192Ir sources will in the future significantly decrease the uncertainty in RAKR of 192Ir brachytherapy

  10. Dosimetry audit on the accuracy of 192Ir brachytherapy source strength determinations in Sweden

    International Nuclear Information System (INIS)

    The absorbed dose delivered to the patient in brachytherapy is directly proportional to the source strength in terms of the reference air-kerma rate (RAKR). Verification of this quantity by the hospitals is widely recognized as an important part of a quality assurance program. An external audit was performed on behalf of the Secondary Standard Dosimetry Laboratory at the Swedish Radiation Protection Authority (SSI). The aim was to investigate how accurately the source-strength in 192Ir brachytherapy is determined at Swedish hospitals. The SSI reference well-type ion chamber and calibrated equipment were used to measure the RAKR of an 192Ir source in each of the 14 Swedish afterloading units. Comparisons with values determined by vendors and hospitals were made. Agreement in values of RAKR as determined by SSI, hospitals and vendors were in all cases within the ±3% uncertainty (at a coverage factor of k=2), typically guaranteed by the vendors. The good agreement reflects the robustness and easy handling of well-type chambers designed for brachytherapy in use by all Swedish hospitals. The 192Ir calibration service planned at SSI will solve the hospitals current problem with recalibration of equipment. SSI can also advise hospitals to follow the IAEA recommendations for measurement techniques and maintenance of equipment. It is worthwhile for the hospitals to establish their own ratio (or deviation) with the vendor and follow it as function of time. Such a mean-ratio embeds systematic differences of various origins and have a lower uncertainty than has the RAKR alone, making it useful for early detection of problems with equipment or routines. SSI could also define requirements for the agreement between source strengths as determined by hospitals and vendors and couple this to an action plan, dependent on level of disagreement, and some kind of reporting to SSI

  11. Design and preliminary test of a free-air ionization chamber for low-energy X-ray

    Institute of Scientific and Technical Information of China (English)

    吴金杰; 杨元第; 王培玮; 陈靖; 柳加成

    2011-01-01

    A free-air ionization chamber in low-energy X-ray has been designed and manufactured at the National Institute of Metrology (NIM, China) according to the defination of air-kerma. The results of a preliminary test show that the leakage current of ionizatio

  12. Strength Training

    Science.gov (United States)

    ... person's own weight to build muscles and strength. Olympic lifting, or powerlifting, which people often think of ... in the group effectively. Here are some basic rules to follow in strength training: Start with body ...

  13. 变压器气垫车托盘强度计算及变形原因分析%Pallet Strength Calculation and Deformation Analysis of Transformer Air Cushion Vehicle

    Institute of Scientific and Technical Information of China (English)

    徐莲环; 韩志伟; 王永刚; 王明胜

    2013-01-01

    利用通用有限元软件ANSYS对运输特高压变压器产品的气垫车托盘结构强度进行了计算,并结合现场使用情况,对气垫车被变形后的托盘卡住的现象进行了原因分析.%The structural strength of the pallet in EHV transformer air cushion vehicle is calculated with ANSYS.According to on-site application,the clamping phenomenon of the pallet after its deformation is analyzed.

  14. Scattering study at free air ionization chamber diaphragm; Estudo do espalhamento no diafragma da camara de ionizacao de ar livre

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Alexandre Lo Bianco dos

    2011-07-01

    The maim of this work consisted in the assessment of the correction factor for air kerma, due to scattered radiation in the diaphragm of the free-air ionization chamber model 481. LNMRl measurements were made to acquire x-ray spectra corresponding to the Qualities RQR-M, described in IEC 61627 standards (2005). These spectra were used as input data in the MC simulations. The operational range of energy spectra provide up to 35 keV. This energy range is typically used in diagnostic radiology, although there is not primary standard for air kerma. The determination of this factor is a fundamental process in the primary standardization of the air kerma. These factors were obtained by computer simulation using the Penelope code. The results are k{sub RQR-M1}=0,9946, k{sub RQR} {sub -M2}=0,9932, k{sub RQR-M3}=0,9978 and k{sub RQR-M4}=0,9885; with uncertainties of 0,007 and coverage factor equal to 2. lt can be concluded that, with respect to the diaphragm, the chamber can be used in the primary standard of air kerma. (author)

  15. Calibration methodology application of kerma area product meters in situ: Preliminary results

    International Nuclear Information System (INIS)

    The kerma-area product (KAP) is a useful quantity to establish the reference levels of conventional X-ray examinations. It can be obtained by measurements carried out with a KAP meter on a plane parallel transmission ionization chamber mounted on the X-ray system. A KAP meter can be calibrated in laboratory or in situ, where it is used. It is important to use one reference KAP meter in order to obtain reliable quantity of doses on the patient. The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. It was manufactured following the IEC 60580 recommendations, an international standard for KAP meters. This study had the aim to calibrate KAP meters using the PDC in situ. Previous studies and the quality control program of the PDC have shown that it has good function in characterization tests of dosimeters with ionization chamber and it also has low energy dependence. Three types of KAP meters were calibrated in four different diagnostic X-ray equipments. The voltages used in the two first calibrations were 50 kV, 70 kV, 100 kV and 120 kV. The other two used 50 kV, 70 kV and 90 kV. This was related to the equipments limitations. The field sizes used for the calibration were 10 cm, 20 cm and 30 cm. The calibrations were done in three different cities with the purpose to analyze the reproducibility of the PDC. The results gave the calibration coefficient for each KAP meter and showed that the PDC can be used as a reference instrument to calibrate clinical KAP meters. - Highlights: • The Patient Dose Calibrator (PDC) is a new equipment from Radcal that measures KAP. • This study aimed the calibration of KAP meters in situ using the PDC as a reference. • The method used for the calibration of the KAP meters was the tandem method. • This instrument calculates the dose that the patient receives during an X-ray examination. • The calibration procedure is important to correct the measurements performed with KAP meters

  16. DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements.

    Science.gov (United States)

    Egbert, Stephen D; Kerr, George D; Cullings, Harry M

    2007-11-01

    Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses of in situ sample measurements of neutron activation products such as (32)P,(36)Cl,(39)Ar,(41)Ca, (60)Co,(63)Ni,(152)Eu, and (154)Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy groups, 101 ground distances, 5 heights, 4 radiation source components, 2 cities. The DS02 code uses these fluences partitioned to a prompt and delayed portion, collapsed to 58 energy groups and restricted to 97 ground distances. This is because the fluence spectra were required to be in the same format that was used in the older Dosimetry System 1986 (DS86) computer code, of which the DS02 computer code is a modification. The 2002 calculation fluences and the collapsed DS02 code fluences are presented and briefly discussed. A report on DS02, which is available on the website at the Radiation Effects Research Foundation, provides tables and figures of the A-bomb neutron and gamma-ray output used as the sources in the 2002 radiation transport calculations. While figures illustrating the fluence spectra at several ground ranges are presented in the DS02 Report, it does not include any tables of the calculated fluence spectra in the DS02 report. This paper provides, at several standard distances from the hypocenter, the numerical information which is required to translate the FIA neutron fluences given in DS02 to a neutron activation measurement or neutron and gamma-ray soft-tissue dose. PMID:17643260

  17. 基于ANSYS的往复式空气压缩机活塞杆的强度分析%Strength Analysis of Piston Rod of Reciprocating Type Air Compressor Based on ANSYS

    Institute of Scientific and Technical Information of China (English)

    李明; 武伟

    2015-01-01

    活塞杆是往复式空气压缩机的核心部件和易损件,活塞杆断裂造成的设备故障占重大安全事故的1/4以上。在往复式空气压缩机的运行过程中活塞杆推动活塞做往复运动并承受拉、压两种工况交变载荷,因此活塞杆的断裂与频繁的交变作用力密切相关。本文以大型往复式空气压缩机活塞杆为研究对象,应用有限元分析软件ANSYS对其进行结构强度分析以确定能否满足静强度及疲劳强度安全系数要求。其结论对往复式空气压缩机活塞杆的设计与优化具有一定的理论指导意义。%Piston rod is the core and vulnerable component of reciprocating type air compressor. The equipment failure ratio caused by piston rod fracture is more than 1/4. During the operational process of reciprocating type air compressor, the pistons were propelled by piston rods to do alternative motion. The piston rod was beard cyclic loading in push and pressure working conditions, so the piston rod fracture is closely related to the frequent alternating force. In this paper, the piston rod of large scale reciprocating type air compressor was researched as subject, the structure strength of piston rod was analyzed by finite element analysis software ANSYS. The simulated results were used for evaluating static strength and fatigue strength request. The analysis results provide some theoretical guidance for designing and improving piston rod of reciprocating type air compressor.

  18. PTRAC file utilization for calculation of free-air ionization chamber correction factors by MCNPX

    International Nuclear Information System (INIS)

    A free-air ionization chamber is used as a standard of photon air-kerma. Several correction factors are applied to the air-kerma value. Correction factors for electron loss: k(loss) and for additional ionization current caused by photon scatter: k(sc), photon fluorescence: k(fl), photon transmission through diaphragm edge k(dtr), and photon scatter from the surface of the diaphragm aperture k(dsc) were determined by the MCNPX code utilizing information stored in Particle Track (PTRAC) output files. Individual steps of the procedure are described and the calculated values of the correction factors are presented. The values are in agreement with the correction factors published in the literature for similar free-air chambers and low-energy photons. (authors)

  19. Characterization of a free air ionization chamber for low energies

    International Nuclear Information System (INIS)

    Free air ionization chambers are used by most primary metrology laboratories as primary standards of the quantities air kerma and exposure in X-ray beams. The free air ionization chamber for low energies of the Calibration Laboratory (LCI) of IPEN showed in a characterization test a problem in the set responsible for the variation of its sensitive volume. After a modification in the support of the micrometers used for the movement of the internal cylinder and the establishment of a new alignment system protocol, the tests were redone. The objective of this work was to present the results obtained in the new condition. (author)

  20. Evaluation of skin entry kerma in radiological examinations at the Hospital de Clinicas, Parana, Brazil; Avaliacao de kerma de entrada na pele em exames radiologicos no Hospital de Clinicas do Parana, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Lorena E.; Schelin, Hugo R.; Santos, Amanda C. dos; Bunick, Ana Paula; Paschuk, Sergei; Denyak, Valeriy [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Tilly Junior, Joao G. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Hospital de Clinicas; Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE/DEN), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-10-26

    This paper evaluates the skin entry dose of pediatric and adults patients when submitted to radiological examinations at the Hospital de Clinicas do Parana, Brazil, as part integrate of the data assessment of International Atomic Energy Agency (IAEA) for Latin America. It was performed measurements of dose for evaluation of skin entry kerma in pediatric patients in thorax AP/PA examinations, adults of thorax in AP/PA, cranio caudal mammography and median lateral and patients of computerized tomography in examination of head, thorax and abdomen. The obtained data demonstrate the necessity of verification of diagnostic analysis standards. The great value amplitudes demonstrate the incompatibility of examination executions with those recommended by the literature. The dose values presented partially inside the range recommended and the other over the expected for the due examination when compared with the literature

  1. Applications of OMI Tropospheric NO(Sub 2) Data: Air Quality Trends in the US and Lightning NO(x) Source Strength

    Science.gov (United States)

    Pickering, Kenneth; Prados, Ana; Bucsela, Eric

    2010-01-01

    This talk will be presented in two parts: 1) an analysis of tropospheric column NO2 trends in the eastern half of the United States over the period 2005 to 2009 and 2) estimation of lightning NO(x) production rates based on OMI observations and lightning flash rate data. The air quality trends in the eastern US will be determined for specific subregions using tropospheric column NO2 data from OMI for 2005 through 2008 and from GOME-2 for 2007 through 2009. This period is characterized by significant NO(x) emission reductions at power plants within most of this region. The air quality trends will be compared with those estimated from continuous emission monitoring data from the power plants compiled by the US Environmental Protection Agency. OMI NO2 data have also been used to estimate lightning NOx production per flash in selected storms near Costa Rica and Panama during the 2007 NASA TC4 field campaign and over the continental US, Gulf of Mexico, and western Atlantic during the summers of 2005 and 2006. The lightning signal is extracted from the OMI data through a custom retrieval in which an NO2 profile representative of convective outflow is used in the airmass factor calculation and the background NO2 column is subtracted from the tropospheric column. When combined with NO(x)/NO2 ratios from the NASA GMT model and observed flash rates, the resulting estimates of NO(x) production per flash are comparable to those estimated obtained from analyses of aircraft data and cloud-resolving modeling.

  2. Study of effective atomic numbers and electron densities, kerma of alcohols, phantom and human organs, and tissues substitutes

    Directory of Open Access Journals (Sweden)

    Singh Vishwanath P.

    2013-01-01

    Full Text Available Effective atomic numbers (ZPIeff and electron densities of eighteen alcohols such as wood alcohol, CH3OH; grain alcohol, C2H5OH; rubbing alcohol, C3H7OH; butanol, C4H9OH; amyl alcohol, C5H11OH; cetyl alcohol, C16H33OH; ethylene glycol, C2H4(OH2; glycerin, C3H5(OH3; PVA, C2H4O; erythritol, C4H6(OH4; xylitol, C5H7(OH5; sorbitol, C6H8(OH6; volemitol, C7H9(OH7; allyl alcohol, C3H5OH; geraniol, C10H17OH; propargyl alcohol, C3H3OH; inositol, C6H6(OH6, and menthol, C10H19OH have been calculated in the photon energy region of 1 keV-100 GeV. The estimated values have been compared with experimental values wherever possible. The comparison of ZPIeff of the alcohols with water phantom and PMMA phantom indicate that the ethylene glycol, glycerin, and PVA are substitute for PMMA phantom and PVA is substitute of water phantom. ZPIeff of alcohols have also been compared with human organs and tissues. Ethylene glycol, glycerin and PVA, allyl alcohol, and wood alcohols are found tissue substitutes for most of human organs. Kerma which is the product of the energy fluence and mass energy-absorption coefficient, have been calculated in the energy region from 1 keV to 20 MeV for the alcohols. The results show the kerma is more or less independent of energy above 100 keV.

  3. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography

    International Nuclear Information System (INIS)

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  4. Doses monitoring in radiology: calibration of air kerma-area product (P{sub KA}) meters; Monitoracao de doses em radiologia: a calibracao de medidores do produto kerma-area (P{sub KA})

    Energy Technology Data Exchange (ETDEWEB)

    Terini, Ricardo Andrade; Campelo, Maria Carolina de Santana; Almeida Junior, Jose Neres de, E-mail: rterini@pucsp.br [Pontificia Universidade Catolica de Sao Paulo (PUC-SP), SP (Brazil); Herdade, Silvio Bruni; Pereira, Marco Aurelio Guedes [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Instituto de Energia e Ambiente

    2013-11-15

    Materials and methods: different qualities of both incident and transmitted beams were utilized in conditions similar to a clinical setting, analyzing the influence from the reference dosimeter, from the distance between meters, from the filtration and from the average beam energy. Calibrations were performed directly against a standard 30 cm{sup 3} cylindrical chamber or a parallel-plate monitor chamber, and indirectly against the PDC meter. Results: the lowest energy dependence was observed for transmitted beams. The cross calibration between the Diamentor E2 and the PDC meters, and the PDC presented the greatest propagation of uncertainties. Conclusion: the calibration coefficient of the PDC meter showed to be more stable with voltage, while the Diamentor E2 calibration coefficient was more variable. On the other hand, the PDC meter presented greater uncertainty in readings (5.0%) than with the use of the monitor chamber (3.5%) as a reference. (author)

  5. 气隙缺陷下不同局部放电强度的SF6分解特性%Decomposition Characteristics of SF6 Under Different Partial Discharge Strengths Caused by Defected Insulation in Air Gap

    Institute of Scientific and Technical Information of China (English)

    唐炬; 任晓龙; 张晓星; 刘帆

    2012-01-01

    为掌握SF6绝缘气体在气隙绝缘缺陷下产生不同强度局部放电引起的分解特性,作者用构建的气隙绝缘缺陷物理模型在sF6分解实验平台上,分别对不同外施电压大小下的sF6进行了96h局部放电分解实验,采用气相色谱法对分解组分进行定量检测与分析,结果表明,SF。在局部放电下均会产生CF4、C02、S02F2和SOF2这4种稳定的分解组分,CF4含量最少,S02F2含量少于SOF2。局部放电强弱对4种组分含量变化及增长率的影响有所不同,且CF4/C02、SOF2/S02F2和(SOF2+S02F2)/(C02+CF4)3组分解组分比值也与局部放电强弱有着一定的关系,可以利用CF。、S02F2和SOF2的含量变化与增长速率以及组分比值范围作为判断局部放电强弱的特征量。%To master the decomposition characteristics of SF6 under different partial discharge (PD) strengths caused by defected insulation in air gap, by use of a constructed physical model of air gap with defected insulation the decomposition experiments of SF6 caused by PD with duration of 96 hours were performed on experimental platform for decomposition of SF6 under three different applied voltages, and the quantitative detection and analysis were implemented by gas chromatography. Experimental results show that the decomposition of SF6 under PD generates four stable decomposed constituents, i.e., CF4, COz, SO2F2 and SOF2, among which the content of CF4 is the least and the content of SO2Fz is less than that of SOF2. The impacts of the strengths of PD on the content variation of the four constituents and their growth rates of the four constituents are different, and the there were certain relations between the PD strength and decomposed constituent ratio of two-constituent assemblies CF4/CO2 and SOF2/SO2F2 as well as between the PD and the decomposed constituent ratio of three-constituent assemblies (SOF2+SO2F2)/(CO2+CF4). Therefore, it is possible

  6. Calculation of the backscattering in water and compared to the values in air; Calculo del factor de retrodispersion en agua y comparativa con los valores en aire

    Energy Technology Data Exchange (ETDEWEB)

    Minano Herrero, J. A.; Sarasa Rubio, A.; Roldan Arjona, J. M.

    2011-07-01

    The purpose of this paper is to calculate values of BSF in water and comparison with data on air 11SF found in the literature. For this simulations have been performed by the Monte Carlo method for calculating values ??kerma water in the presence of a manikin of this material and in the absence thereof. The simulations were performed for monoenergetic beams in order to facilitate the calculation of the BSF for any spectral distribution of those found in the field of radiology.

  7. What is the explanation for the changes to cobalt-60 tissue - air ratios in BJR Supplement 25?

    International Nuclear Information System (INIS)

    Values of tissue - air ratio (TAR) in the recent British Journal of radiology (BJR) Supplement 25 have been increased by nearly 2% over the values which have been accepted for the past 30 years. The need for this was shown by analysis of previous data using scaling laws, together with Monte Carlo calculations and careful re-measurement. However, it was not clear why previous determinations of TAR were in error: it was not, as some workers argued, because scattered radiation had been included in the absorbed dose in the miniphantom, because TAR data in BJR Supplement 17 had been derived from peak scatter factor (PSF), which is not based on the miniphantom concept. The purpose of this paper is to find the real explanation of why the PSF and, therefore, TAR were underestimated for so long. Two definitions of PSF are considered: one based on kerma and one based on dose. This paper relates PSF of either definition to measurements of air kerma by including in the derivation the scatter in the plug which replaces the chamber when it has been removed from the surface of the water phantom. The kerma-based PSF is found to be 2% higher than the simple ratio of chamber readings in phantom and in air. The value of the dose-based definition agrees with that of the Kerma-based definition to within 0.2%. It is the scatter in the replacement plug in the surface of the water phantom which was effectively ignored by previous workers, and which explains the underestimates of around 2% in PSF nd TAR. The value of the dose-based PSF differs slightly from that of the Kerma-based PSF because of the different distributions of primary and scatter photon fluence. (author)

  8. Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on 40Ca and 31P

    International Nuclear Information System (INIS)

    The authors present evaluations of the interaction of 20 to 100 MeV neutrons with calcium and phosphorus, which follows on from the previous work on carbon, nitrogen, and oxygen. The aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. They apply the GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. Total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A ≤ 4 and gamma-rays, and average energy depositions, are determined. The expected accuracy of the calculated cross sections and kerma factors is discussed

  9. Evaluated cross section libraries and kerma factors for neutrons up to 100 MeV on 16O and 14N

    International Nuclear Information System (INIS)

    We present evaluations of the interaction of 20 to 100 MeV neutrons with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra, for light ejectiles with A≤4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al.. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. The evaluated data libraries are available as electronic files

  10. Calculation and evaluation of cross-sections and kerma factors for neutrons up to 100 MeV on {sup 16}O and {sup 14}N

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B. [California Univ., Livermor, CA (United States). Lawrence Livermore National Lab.; Young, P.G.

    1997-03-01

    We present evaluations of the interaction of neutrons with energies between 20 and 100 MeV with oxygen and nitrogen nuclei, which follows on from our previous work on carbon. Our aim is to accurately represent integrated cross sections, inclusive emission spectra, and kerma factors, in a data library which can be used in radiation transport calculations. We apply the FKK-GNASH nuclear model code, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms, and use experimental measurements to optimize the calculations. We determine total, elastic, and nonelastic cross sections, angle-energy correlated emission spectra for light ejectiles with A {<=} 4 and gamma-rays, and average energy depositions. Our results for charged-particle emission spectra agree well with the measurements of Subramanian et al. We compare kerma factors derived from our evaluated cross sections with experimental data, providing an integral benchmarking of our work. (author). 52 refs.

  11. SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

    International Nuclear Information System (INIS)

    Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873

  12. SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

    2015-06-15

    Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.

  13. Development of improved free-air ionisation chamber as absolute dosimetry standard for low-energy X rays in INER

    International Nuclear Information System (INIS)

    The National Radiation Standard Laboratory of the Inst. of Nuclear Energy Research (INER) designed and constructed an improved Attix style free-air ionisation chamber (FAC) for low-energy X-ray measurements. Clinically, X rays in this energy range are used in mammography radiology. This chamber is also used to perform air-kerma measurements. The original Attix two-sectional design was redesigned by INER using the piston design. The correction factors were determined experimentally for volume estimation, ion recombination and air attenuation. The aperture transmission, wall transmission, electron loss and photon scatter correction factors were determined using Monte Carlo calculations. INER established the Bureau International des Poids et Mesures (BIPM) X-ray beam code and performed a comparison of secondary standard air-kerma calibration factors for 10-50 kV low- energy X rays to verify the experimental accuracy and measurement consistency of the improved chamber. The INER-NMIJ/National Inst. of Advanced Industrial Science and Technology (AIST) experimental results comparison using a transfer chamber yielded a difference <1.0% at the 95% confidence level in calibration factors. The overall uncertainty for the X-ray measurement in terms of air kerma was <0.6% at the 95% confidence level. These results indicated that the improved FAC is capable of serving as a primary standard as well as a trace standard in low-energy X-ray calibration services in Taiwan and even forming a basis for the future mammography X-ray air-kerma primary standard. (authors)

  14. Evaluated cross-section libraries and kerma factors for neutrons up to 100 MeV on 12C

    International Nuclear Information System (INIS)

    A program is being carried out at Lawrence Livermore National Laboratory to develop high-energy evaluated nuclear data libraries for use in Monte Carlo simulations of cancer radiation therapy. In this report we describe evaluated cross sections and kerma factors for neutrons with incident energies up to 100 MeV on 12C. The aim of this effort is to incorporate advanced nuclear physics modeling methods, with new experimental measurements, to generate cross section libraries needed for an accurate simulation of dose deposition in fast neutron therapy. The evaluated libraries are based mainly on nuclear model calculations, benchmarked to experimental measurements where they exist. We use the GNASH code system, which includes Hauser-Feshbach, preequilibrium, and direct reaction mechanisms. The libraries tabulate elastic and nonelastic cross sections, angle-energy correlated production spectra for light ejectiles with A≤and kinetic energies given to light ejectiles and heavy recoil fragments. The major steps involved in this effort are: (1) development and validation of nuclear models for incident energies up to 100 MeV; (2) collation of experimental measurements, including new results from Louvain-la-Nueve and Los Alamos; (3) extension of the Livermore ENDL formats for representing high-energy data; (4) calculation and evaluation of nuclear data; and (5) validation of the libraries. We describe the evaluations in detail, with particular emphasis on our new high-energy modeling developments. Our evaluations agree well with experimental measurements of integrated and differential cross sections. We compare our results with the recent ENDF/B-VI evaluation which extends up to 32 MeV

  15. RESEARCH ON EARLY STRENGTH AND FREEZE-PROOF RESISTANCE OF AIR-ENTRAINED CONCRETE UNDER 3 ℃CURING%3℃养护下引气混凝土早期强度及抗冻性能研究

    Institute of Scientific and Technical Information of China (English)

    张凯; 王起才; 王庆石; 李盛; 李建新

    2015-01-01

    采用强度试验、压汞法、气孔分析法、快速冻融法,以低温(3±0.2)℃养护下引气混凝土为研究对象,对混凝土的强度、孔隙结构及抗冻耐久性进行了研究。结果表明:在3℃养护下,随着含气量的提高,孔径均匀分布,显著改善了混凝土的内部孔隙结构,但比标准养护条件下同等含气量混凝土的孔结构粗化。为更好地阐述混凝土实际强度受含气量的影响,由孔隙结构可进一步推算出3℃养护下混凝土的实际抗压强度,并与标准养护条件下实际抗压强度对比,显示两者之间的不同。%The strength, the pore structure and freeze-proof durability of air-entrained concrete under 3 ℃temperature curing and with different air contents were researched by taking air-entrained concrete under low temperature curing (3 ±0.2 ) ℃ as the object, adopting strength test mercury intrusion method, pore analytical method and fast freeze-thaw method.The results showed that when concrete of 3 ℃ temperature curing, as the air content was increased, the distribution of pore diameter was uniform and the interior pore structure of concrete was improved significantly, however, the pore structure under the room curing at the same air content of concrete was lower than under 3 ℃curing.In order to expound the influence of air content on the actual concrete strength in an even better fashion, the concrete compressive strength under 3 ℃curing can further be estimated by pore structure, which was compared with the room curing actual compressive strength, showing the difference between the two.

  16. Variation of the Earth's magnetic field strength in South America during the last two millennia: New results from historical buildings of Buenos Aires and re-evaluation of regional data

    Science.gov (United States)

    Goguitchaichvili, Avto; Morales, Juan; Schavelzon, Daniel; Vásquez, Carlos; Gogorza, Claudia S. G.; Loponte, Daniel; Rapalini, Augusto

    2015-08-01

    The causes of the systematic decay of the Earth's Magnetic Field strength since eighteen century have been a matter of debate during the last decade. It is also well known that such variations may have completely different expressions under an area characterized with strong magnetic anomalies, such as the South Atlantic Magnetic Anomaly. To fully understand these atypical phenomena, it is crucial to retrieve the past evolution of Earth's magnetic field beyond the observatory records. We report on detailed rock-magnetic and archeointensity investigations from some well-studied historical buildings of Buenos Aires city, located at the heart of the South Atlantic Magnetic Anomaly. Samples consist of bricks, tiles, fireplaces and pottery, which are considered as highly suitable materials for archaeointensity studies. The dating is ascertained by historical documents complemented by archeological constraints. Eighteen out of 26 analyzed samples yield reliable absolute intensity determinations. The site-mean archaeointensity values obtained in this study range from 28.5 to 43.5 μT, with corresponding virtual axial dipole moments (VADMs) ranging from 5.3 to 8.04 × 1022 Am2. Most determinations obtained in the present study are in remarkable agreement with the values predicted by the time varying field model CALS10k.1b (Korte et al., 2011). For the older periods the recently available SHA.DIF.14 model (Pavon-Carrasco et al., 2014) seems to have greater resolution. South American archaeointensity database now includes absolute intensities from 400 to 1930 AD based on 63 selected archaeointensity determinations. The data set reveals several distinct periods of quite large fluctuations of intensity. However, most data are concentrated into a relatively narrow interval from AD 1250 to AD 1450. At the beginning of the record, values between 400 AD and 830 AD match well with ARCH3k.1 model. Some general features may be detected: the time intervals from about AD 400 to 950 and

  17. Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography; Caracterizacao de uma camara de ionizacao de ar-livre em feixes diretos de raios X utilizados em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Mateus Hilario de

    2014-08-01

    At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribution for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter. (author)

  18. Human occupations and environmental changes in the Nile valley during the Holocene: The case of Kerma in Upper Nubia (northern Sudan)

    Science.gov (United States)

    Honegger, Matthieu; Williams, Martin

    2015-12-01

    Our article presents a detailed Holocene archaeological sequence from the Nile Valley at Kerma in Upper Nubia, northern Sudan. This sequence retraces the evolution of human populations thanks to the study of several sites, supported by 90 14C dates. Reconstruction of the environmental changes was supported by a study of dated stratigraphic sections located near the archaeological sites studied, and illustrates the effects on human occupation of changes in river flow and floods, which are in turn forced by climatic changes. The results shed new light on the evolutionary dynamics of the Holocene populations in Nile Valley, little known due to the numerous hiatuses in occupation. When compared with the situation in the Sahara and the rest of the Nile Valley, they confirm that the initial occupation took place ca. 10.5 kyr BP after the start of the African Humid Period, followed by a migration towards the banks of the Nile commencing 7.3 kyr BP. They also confirm the appearance of the Neolithic by ca. 8.0 kyr BP. The Kerma stratigraphic sequences show two prosperous periods (10-8 and 7-6 kyr BP) and two hiatuses in the occupation of the sites (7.5-7.1 and 6.0-5.4 kyr BP), resulting from increased aridity.

  19. Evaluation of cross sections and calculation of kerma factors for neutrons up to 80 MeV on {sup 12}C

    Energy Technology Data Exchange (ETDEWEB)

    Harada, M.; Watanabe, Y. [Kyushu Univ., Fukuoka (Japan); Chiba, S.; Fukahori, T.

    1997-03-01

    We have evaluated the cross sections for neutrons with incident energies from 20 to 80 MeV on {sup 12}C for the JENDL high-energy file. The total cross sections were determined by a generalized least-squares method with available experimental data. The cross sections of elastic and inelastic scattering to the first 2{sup +} were evaluated with the theoretical calculations. The optical potentials necessary for these calculations were derived using a microscopic approach by Jeukenne-Lejeune-Mahaux. For the evaluation of double differential emission cross sections (DDXs), we have developed a code system SCINFUL/DDX in which total 35 reactions including the 3-body simultaneous breakup process (n+{sup 12}C {yields} n+{alpha}+{sup 8}Be) can be taken into consideration in terms of a Monte Carlo method, and have calculated the DDXs of all light-emissions (A{<=}4) and heavier reaction products. The results for protons, deuterons, and alphas showed overall good agreement with experimental data. The code is also applicable for calculations of total and partial kerma factors. Total kerma factors calculated for energies from 20 to 80 MeV were compared with the measurements and the other latest evaluations from the viewpoints of medical application and nuclear heating estimation. (author)

  20. Air kerma rate measurements of 192Ir source in Gammamed 12i HDR/PDR unit using well type ionization chamber

    International Nuclear Information System (INIS)

    The use of high dose rate (HDR) brachytherapy in radiotherapy department has increased nowadays. The initial activity of 192Ir sources, used in high dose rate brachytherapy unit is approximately 10 Ci. About 3 to 4 times per year, a replacement is made of these sources, because of the decay half-life of 192Ir with 73.83 days. It is recommended that each time a new HDR source is installed for use in clinical routine, a source calibration in the hospital should be carried out

  1. Conception and realization of a parallel-plate free-air ionization chamber for the absolute dosimetry of an ultrasoft X-ray beam

    International Nuclear Information System (INIS)

    We report the design of a millimeter-sized parallel plate free-air ionization chamber (IC) aimed at determining the absolute air kerma rate of an ultra-soft X-ray beam (E = 1.5 keV). The size of the IC was determined so that the measurement volume satisfies the condition of charged-particle equilibrium. The correction factors necessary to properly measure the absolute kerma using the IC have been established. Particular attention was given to the determination of the effective mean energy for the 1.5 keV photons using the PENELOPE code. Other correction factors were determined by means of computer simulation (COMSOL™and FLUKA). Measurements of air kerma rates under specific operating parameters of the lab-bench X-ray source have been performed at various distances from that source and compared to Monte Carlo calculations. We show that the developed ionization chamber makes it possible to determine accurate photon fluence rates in routine work and will constitute substantial time-savings for future radiobiological experiments based on the use of ultra-soft X-rays

  2. A study of the microstructural basis for the strength and toughness properties of water-quenched and air-cooled HSLA-100, HSLA-100 with increased copper, and a ULCB steel.

    OpenAIRE

    Mohr, Thomas Campion

    1991-01-01

    Approved for public release: Distribution is unlimited The microstructural basis for strength of the water-quenched and aircooled HSLA-100, HSLA-100 with increased copper, and a ULCB steel was investigated by conducting an inclusion study and characterizing the microstructure of each of the steels. For the inclusion study, the SEM was used to examine a large number of fields and determine inclusion morphology while the EDX was used to determine inclusion composition. The mic...

  3. Design and preliminary test of a free-air ionization chamber for low-energy X-ray

    Institute of Scientific and Technical Information of China (English)

    WU Jin-Jie; YANG Yuan-Di; WANG Pei-Wei; CHEN Jing; LIU Jia-Cheng

    2011-01-01

    A free-air ionization chamber in low-energy X-ray has been designed and manufactured at theNational Institute of Metrology (NIM, China) according to the defination of alr-kerma. The results of a preliminary test show that the leakage current of ionization chamber is around 2×10A, and the correction factor of ion recombination for the ionization chamber is also obtained. The free-air ionization chamber is suitable for the primary standard in low-energy X-rays.

  4. Calculation of conversion coefficients Hp(3)/K air using the PENELOPE Monte Carlo code and comparison with MCNP calculation results

    International Nuclear Information System (INIS)

    The authors report calculations performed using the MNCP and PENELOPE codes to determine the Hp(3)/K air conversion coefficient which allows the Hp(3) dose equivalent to be determined from the measured value of the kerma in the air. They report the definition of the phantom, a 20 cm diameter and 20 cm high cylinder which is considered as representative of a head. Calculations are performed for an energy range corresponding to interventional radiology or cardiology (20 keV-110 keV). Results obtained with both codes are compared

  5. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.;

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots is...... measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...

  6. High strength ferritic alloy

    International Nuclear Information System (INIS)

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  7. Air Pollution

    Science.gov (United States)

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  8. Air Pollution

    Science.gov (United States)

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, pollen and ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, ...

  9. Stability results of a free air ionization chamber in standard mammography beams

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Natalia F.; Xavier, Marcos; Vivolo, Vitor; Caldas, Linda V.E., E-mail: nsilva@ipen.br, E-mail: mxavier@ipen.br, E-mail: vivolo@ipen.br, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Free air ionization chambers are absolute dosimeters, because they can measure basic physical quantities directly without the need of their calibration in a standard radiation beam. They are used for measuring exposure and air kerma in X and gamma radiation beams. The Calibration Laboratory (LCI) of IPEN has a free air ionization chamber of the cylindrical type for low energies. The characterization of this ionization chamber was already performed and reported in a previous study. After a modification in the support of the micrometers used for the movement of the internal cylinder devices, the tests were redone. The objective of this work was to present the new alignment protocol of the free air ionization chamber in low energies of X-ray beams of standard mammography qualities, assuring the positioning reproducibility, and new results of stability tests performed with the application of this protocol will be presented. (author)

  10. Advanced high strength steels for automotive industry

    International Nuclear Information System (INIS)

    The car industry is facing pressure because of the growing demand for more fuel-efficient passenger cars. In order to limit energy consumption and air pollution the weight of the car body has to be reduced. At the same time, high levels of safety have to be guaranteed. In this situation, the choice of material becomes a key decision in car design. As a response to the requirements of the automotive sector, high strength steels and advanced high strength steels have been developed by the steel industry. These modern steel grades offer an excellent balance of low cost, light weight and mechanical properties. (Author) 48 refs.

  11. State of art an Overview on the Tensile Strength and Flexural Strength of Concrete in different Curing Methods

    Directory of Open Access Journals (Sweden)

    J. Allen Paul Edson

    2014-11-01

    Full Text Available The concrete is made of different ingredients such as cement, fine aggregate, and coarse aggregate but it is a homogeneous material when it is in a harden concrete. The strength of concrete decides the life span of any concrete structure. The factors which affect the strength of concrete are the type of material used, size of aggregate, water cement ratio, improper compaction and improper curing. Curing is one of the major factors in the failure of concrete. Curing is defined as the process of promoting the hydration of cement. The grade used in the manufacture of concrete may be M20, M30 grade. This paper deals with the overview on the tensile strength and flexural strength of concrete when the concrete is exposed to various curing methods such as Water curing (Ponding and Immersion, Air Curing (Dry air curing, and plastic film curing at 3 days, 7 days, 28 days and 56 days. It is studied that the tensile and flexural strength of concrete during immersion method is high when compared with Air curing and plastic film curing. It is found that the water curing is the most effective method of curing with the maximum of 10% increase in tensile strength and 15% increase in flexural strength of concrete when compared with other curing methods. On comparison with self compacting concrete (SCC and Normal cement concrete (NCC under different curing methods the tensile strength and flexural strength of SCC is high than NCC.

  12. ZZ DLC-14 AIR, Group Constant Library of Secondary Gamma Transport in Air for ANISN Calculation

    International Nuclear Information System (INIS)

    1 - Nature of physical problem solved: Format: ANISN, DOT, MORSE (FIDO format); Number of groups: 22 neutron / 18 gamma-ray; Nuclides: air; Origin: ENDF/B for neutron cross sections, DLC-4/HPIC for gamma-ray and DLC-12/POPLIB for secondary gamma-ray production. Weighting spectrum: 1/E for neutron cross sections. The basic idea behind the distribution of this ANISN input data is to allow potential users to repeat the ANISN calculations reported in ref. (1). It is felt that it will be more economical to repeat the calculations rather than to distribute the results of the Straker-Gritzner (1) calculations. However, the cross section part of the data can actually be used in DOT or MORSE or any transport code which will accept input cross section in the FIDO format. 2 - Method of solution: The sample input data for ANISN are for a P5, S16 calculation of the transport of neutrons and secondary gamma-rays from a 12.2 to 15 MeV point neutron source in an infinite air medium. The source is actually uniformly distributed in the first interval (500 cm radius) of a spherical medium of air with radius 3005 meters. The problem is set up for calculating various 'detector responses' by means of the 'activity' option available with ANISN. This is accomplished by providing a cross section table for a 'material' which has detector responses in certain table positions. Then the inclusion of appropriate input data for 22$ and 23$ arrays causes the group fluxes to be multiplied by the group response function values to give the desired answer. The neutron detector responses calculated by this sample problem are Henderson tissue dose, Snyder-Neufeld dose, tissue kerma, and air kerma. The gamma-ray response functions calculated are Henderson tissue dose and air kerma. The neutron cross sections were first reduced from point data from ENDF/B to a 104 fine group structure with a modified version of CSP, assuming a 1/E weighting factor. The gamma-ray data were reduced from point data from DLC

  13. Performance of An Adjustable Strength Permanent Magnet Quadrupole

    International Nuclear Information System (INIS)

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic CL and field quality made using an air bearing rotating coil system. The magnetic CL stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic CL. Calibration procedures as well as CL measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported

  14. Performance of an Adjustable Strength Permanent Magnet Quadrupole

    CERN Document Server

    Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

    2005-01-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic centerline and field quality made using an air bearing rotating coil system. The magnetic centerline stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic centerline. Calibration procedures as well as centerline measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

  15. Photon and neutron fluence-to-kerma conversion factors for ICRP-1975 reference man using improved elemental compositions for bone and marrow of the skeleton

    International Nuclear Information System (INIS)

    Findings of a recent ORNL review, and of other reviews, which have been discussed at the Late Effects Workshop on Dosimetry of Atomic Bomb Survivors, 29th Annual Meeting of the Radiation Research Society, Minneapolis, Minnesota, 31 May 1981, and the Symposium on Reevaluations of Dosimetric Factors, Hiroshima and Nagasaki, US Department of Energy, Germantown, Maryland, 5 and 6 September 1981, have clearly established a need to revise the dosimetry for the A-bomb survivors. This effort will involve several divisions at ORNL, several other national laboratories, and several consulting firms. One of the main tasks of the Health and Safety Research Division at ORNL is to provide revised estimates of various organ-dose parameters related to a survivor's neutron and gamma-ray exposures. The objectives of the work summarized in this report were: (a) to better define the elemental composition of various skeletal components of ICRP-1975 Reference Man, and (b) to investigate photon and neutron fluence-to-kerma conversion factors for various total-body and organ-tissue components of ICRP-1975 Reference man as revised here. Scaled down mathematical descriptions of the volumes and shapes of the total body and internal organs of Reference Man will be used, of course, in the organ-dose calculations for A-bomb survivors

  16. Subcritical crack growth and long-term strength in rock and high-strength and ultra low-permeability concrete

    International Nuclear Information System (INIS)

    High-strength and ultra low-permeability concrete (HSULPC) is a strong candidate for a radioactive waste package containing transuranic radionuclides (TRU waste) for geological disposal. The information and knowledge of the time-dependent fracturing of HSULPC and surrounding rock mass are essential to assess the long-term stability of such underground repositories. Here we measured crack velocity in andesite and HSULPC both in air and water to examine slow crack growth (subcritical crack growth) by Double-Torsion method. In air, the crack velocity in andesite increased when the temperature increased. On the other hand, the temperature had little effect on the crack velocity in HSULPC in air. In water, the crack velocity increased when the temperature was higher for both andesite and HSULPC. By using the experimental results of subcritical crack growth, the long-term strength was estimated based on the model of a single crack subjected to tension in an infinite plate. It was shown that the long-term strength of HSULPC was higher than that of andesite. When the temperature increased, the long-term strength of andesite both in air and water and that of HSULPC in water decreased. The long-term strength in water was smaller than that in air for both materials. It is concluded that water remarkably affects subcritical crack growth and the long-term strength in these materials. (author)

  17. Determination of the diaphragm correction factor of the LNE-LNHB free-air chambers for low and medium energy X-rays

    International Nuclear Information System (INIS)

    Until recently, in the establishment of the French LNE-LNHB national reference in terms of air kerma for low and medium energy X-rays, the effect of the diaphragm located at the entrance of the free-air ionization chambers was not sufficiently taken into account. This report describes the different Monte Carlo computations made in 2010-2011 with the PENELOPE Monte Carlo code to determine a correction factor (kdia) describing the influence of the different incident photon interactions taking place into the diaphragm on the deposited energy in the collecting volume. (author)

  18. Air Abrasion

    Science.gov (United States)

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  19. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  20. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  1. Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions

    Directory of Open Access Journals (Sweden)

    Othuman Mydin M.A.

    2014-01-01

    Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.

  2. The Strength of Varying Tie Strength

    CERN Document Server

    Bruggeman, Jeroen

    2012-01-01

    "The Strength of Weak Ties" argument (Granovetter 1973) says that the most valuable information is best collected through bridging ties with other social circles than one's own, and that those ties tend to be weak. Aral and Van Alstyne (2011) added that to access complex information, actors need strong ties ("high bandwidth") instead. These insights I generalize by pointing at actors' interest to avoid spending large resources on low value information. Weak ties are well-suited for relatively simple information at low transmission and tie maintenance costs, whereas for complex information, the best outcomes are expected for those actors who vary their bandwidths along with the value of information accessed. To support my claim I use all patents in the USA (two million) over the period 1975-1999. I also show that in rationalized fields, such as technology, bandwidth correlates highly with the value of information, which provides support for using this proxy if value can't be measured directly. Finally, I show ...

  3. Assessment of corrective factors for the LNHB reference measurement in terms of Kr air for iodine 125; Evaluation des facteurs de correction a apporter a la mesure de la reference LNHB en termes de k{sub r} air pour l'iode 125

    Energy Technology Data Exchange (ETDEWEB)

    Gouriou, J.; Aubineau-Laniece, I.; Cutarella, D.; Plagnard, J. [CEA Saclay, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), 91 - Gif-sur-Yvette (France)

    2010-07-01

    The LNHB (Laboratoire National Henri Becquerel) is currently developing a new primary reference for low dose rate curietherapy with iodine 125 in terms of reference kerma in air. This includes an innovative sensor: an ionization chamber with a toroidal air wall. The authors present Monte Carlo calculations performed for the determination of corrective factors to be applied to come down to reference conditions or to correct possible measurement errors. Calculations have been performed for the specific geometries of BEBIG sources which are used for ophthalmic and prostatic curietherapy treatments

  4. Hand grip strength

    DEFF Research Database (Denmark)

    Frederiksen, Henrik; Gaist, David; Petersen, Hans Christian;

    2002-01-01

    in life is a major problem in terms of prevalence, morbidity, functional limitations, and quality of life. It is therefore of interest to find a phenotype reflecting physical functioning which has a relatively high heritability and which can be measured in large samples. Hand grip strength is known......Physical functioning late in life has been shown to be affected by genetic factors. Only a few genetic variants have been suggested to be associated with physical functioning, and this only in selected populations (e.g., young healthy males and elite athletes). Declining physical functioning late......-55%). A powerful design to detect genes associated with a phenotype is obtained using the extreme discordant and concordant sib pairs, of whom 28 and 77 dizygotic twin pairs, respectively, were found in this study. Hence grip strength is a suitable phenotype for identifying genetic variants of importance...

  5. Gaussian Discriminating Strength

    OpenAIRE

    Rigovacca, Luca; Farace, Alessandro; De Pasquale, Antonella; Giovannetti, Vittorio

    2015-01-01

    We present a quantifier of non-classical correlations for bipartite, multi-mode Gaussian states. It is derived from the Discriminating Strength measure, introduced for finite dimensional systems in A. Farace et al., New. J. Phys. 16, 073010 (2014). As the latter the new measure exploits the Quantum Chernoff Bound to gauge the susceptibility of the composite system with respect to local perturbations induced by unitary gates extracted from a suitable set of allowed transformations (the latter ...

  6. Strength Pada Amalgam

    OpenAIRE

    Sri Handayani

    2008-01-01

    Amalgam didefinisikan sebagai campuran dari dua atau beberapa logam (alloy) yang salah satunya adalali merkuri. Dental amalgam sendiri merupakan campuran dari merkuri (Hg), perak (Ag), timah (Sn), tembaga (Cu) dan bahan-bahan lain yang memiliki fungsinya masing-masing, dimana sebagian diantaranya akan saling mengatasi kekurangan yang ditimbulkan logam lain, jika logam tersebut dikombinasikan dengan perbandingan yang tepat. Amalgam mempunyai strength (kekuatan) yang cukup besar sehingga dap...

  7. Characterization of the new free-air primary standard for low-energy X-rays at CMI

    International Nuclear Information System (INIS)

    In 2011 a decision was made by Czech Metrology Institute to build a free-air ionization chamber (FAC) intended to be used as a primary standard of air kerma rate for low-energy X-rays (photon energy below 50 keV, including mammography X-ray qualities) in order to replace the currently used secondary ionization chamber and to decrease the uncertainty of air kerma reference value. In the period 2011–2012, the FAC has been designed, manufactured and put into operation. Its performance was tested using a calibrated secondary chamber and then by an informal comparison with a national primary standard of BEV (Austria). Physical characteristics of the FAC are described and individual correction factors are discussed focusing on computational methods utilized in their estimation. Summary of the correction factors with the uncertainty budget is presented. - Highlights: • A new primary standard for low-energy X-ray beam constructed at CMI. • Correction factors calculated by MCNPX simulations. • The chamber performance tested by an informal comparison with BEV (Austria). • The chamber considered ready for key comparison and standardization of X-ray beams

  8. Realization of commercial high strength HEPA filters

    International Nuclear Information System (INIS)

    HEPA-filter media though having excellent particle removal efficiencies, remain characterized as rather brittle, fragile and weak materials. As a result, undesired structural damage followed by significant losses in filtration efficiency can easily occur in handling, transport, and even normal operation of filter units. In recent years extensive investigations into the structural limits of HEPA filters in dry air and under extended exposure to high humidity airflow have been carried out. In the course of this work the failure modes and the underlying failure mechanisms were thoroughly studied. On the basis of the information obtained, considerable improvements in the structural strength of HEPA filters could be achieved. As verified by removal efficiency tests, differential pressures up to 56kPa in dry air and 15kPa after extended operation under fog conditions were proven to be sustainable without mechanical damage to the filter medium. In cooperation with three major European filter manufacturers the know-how gained has been transferred into practical application through development of commercially available high-strength filter units. Three new KWU (Siemens-Kraftwerksunion) nuclear power plants in Germany have already been fully equipped with HEPA filters of this improved design. The German licensing authorities are now considering modifications of their requirement specifications to reflect the increased strength of the new filter units

  9. Gaussian discriminating strength

    Science.gov (United States)

    Rigovacca, L.; Farace, A.; De Pasquale, A.; Giovannetti, V.

    2015-10-01

    We present a quantifier of nonclassical correlations for bipartite, multimode Gaussian states. It is derived from the Discriminating Strength measure, introduced for finite dimensional systems in Farace et al., [New J. Phys. 16, 073010 (2014), 10.1088/1367-2630/16/7/073010]. As the latter the new measure exploits the quantum Chernoff bound to gauge the susceptibility of the composite system with respect to local perturbations induced by unitary gates extracted from a suitable set of allowed transformations (the latter being identified by posing some general requirements). Closed expressions are provided for the case of two-mode Gaussian states obtained by squeezing or by linearly mixing via a beam splitter a factorized two-mode thermal state. For these density matrices, we study how nonclassical correlations are related with the entanglement present in the system and with its total photon number.

  10. Water's Hydrogen Bond Strength

    CERN Document Server

    Chaplin, Martin

    2007-01-01

    Water is necessary both for the evolution of life and its continuance. It possesses particular properties that cannot be found in other materials and that are required for life-giving processes. These properties are brought about by the hydrogen bonded environment particularly evident in liquid water. Each liquid water molecule is involved in about four hydrogen bonds with strengths considerably less than covalent bonds but considerably greater than the natural thermal energy. These hydrogen bonds are roughly tetrahedrally arranged such that when strongly formed the local clustering expands, decreasing the density. Such low density structuring naturally occurs at low and supercooled temperatures and gives rise to many physical and chemical properties that evidence the particular uniqueness of liquid water. If aqueous hydrogen bonds were actually somewhat stronger then water would behave similar to a glass, whereas if they were weaker then water would be a gas and only exist as a liquid at sub-zero temperature...

  11. Microcracking and durability of high strength concretes

    International Nuclear Information System (INIS)

    Durability of 28 days compressive strength concrete of 20 to 120 MPa has been studied. The ability of concrete to transport aggressive agents has been determined for four properties: the air permeability, the chloride diffusivity, the water absorption and the carbonation. A chloride migration test for high and very high strength concrete (HSC and VHSC) has been built. The relationship between transport properties and the compressive strength after one and 28 days of humid curing has always the same shape: transport decreases when strength increases. However, transport properties often vary in the ordinary concrete field. Beyond, the domain is much more limited. The relationship between transport properties and strength valid for ordinary concrete can not be simply extrapolated for HSC and VHSC. To determine the part of microcracking of HSC and VHSC, concrete behaviour stored in two mediums has been studied: the ones shaming the storing condition of concrete in auto-desiccation, the others reproducing the storing conditions of concrete in desiccation. Auto-desiccation (measuring relative humidity at balance) and desiccation (measuring mass losses) have been showed. Microcracks and shrinkage strains have been measured. It has been showed that auto-desiccation microcracks proving in HSC or VHSC don't question the durability. Microcracks, as for permeability, do not develop between 28 days and one year. On the contrary, desiccation microcracks observed in HSC and VHSC, increase with transport properties between 28 days and 1.5 year. Thus, a bulk concrete is always more durable than a cover concrete. At last, the good influence of increase of curing of 1 to 28 days on the transport of all concretes has been emphasized. (author)

  12. Air Pollution

    OpenAIRE

    Lawther, P. J.

    2014-01-01

    The human costs of air pollution are considerable in Jordan. According to a report published in 2000 by the World Bank under the Mediterranean Environmental Technical Assistance Program (METAP), approximately 600 people die prematurely each year in Jordan because of urban pollution. 50-90% of air pollution in Jordanian towns is caused by road traffic. Readings taken in 2007 by Jordanian researchers showed that levels of black carbon particles in the air were higher in urban areas (caused by v...

  13. Strength degradation of oxidized graphite support column in VHTR

    International Nuclear Information System (INIS)

    Air-ingress events caused by large pipe breaks are important accidents considered in the design of Very High Temperature Gas-Cooled Reactors (VHTRs). A main safety concern for this type of event is the possibility of core collapse following the failure of the graphite support column, which can be oxidized by ingressed air. In this study, the main target is to predict the strength of the oxidized graphite support column. Through compression tests for fresh and oxidized graphite columns, the compressive strength of IG-110 was obtained. The buckling strength of the IG-110 column is expressed using the following empirical straight-line formula: σcr,buckling=91.34-1.01(L/r). Graphite oxidation in Zone 1 is volume reaction and that in Zone 3 is surface reaction. We notice that the ultimate strength of the graphite column oxidized in Zones 1 and 3 only depends on the slenderness ratio and bulk density. Its strength degradation oxidized in Zone 1 is expressed in the following nondimensional form: σ/σ0=exp(-kd), k=0.114. We found that the strength degradation of a graphite column, oxidized in Zone 3, follows the above buckling empirical formula as the slenderness of the column changes. (author)

  14. Character strengths and virtues

    Directory of Open Access Journals (Sweden)

    Mariana Gancedo

    2015-09-01

    Full Text Available The target of this work is to carry out a critical analysis about some of the underlying epistemological assumptions in Peterson and Seligman’s book Character Strengths and Virtues. A handbook and classifications (2004. This is a theoretical investigation that belongs to the epistemology of psychology field. According to the theory proposed by Serroni Copello (2003, a critic progress rational criterion is methodologically applied. The analysis points out some epistemological weakness that leads to incongruences in the statements and conclusions of the investigations, such as: the absence of a unified theory, a candid search of objectivity, and the superposition of implicit paradigms. It also takes notice of a causal and elementary logic -which goes against today’s scientific paradigm-, and the strong American culture zeitgeist present in the principles of Positive Psychology. Finally, some ethic problems are displayed, in particular the step taken from a descriptive attitude –characteristic of science- toward a prescriptive attitude –characteristic of moral codes-. 

  15. Study on the repeatability and correlation of warm-air and solid coupled mode ultrasound bone strength device%热固耦合式超声骨强度仪的可重复性及相关性研究

    Institute of Scientific and Technical Information of China (English)

    王杰; 倪朝民; 陈焱焱; 马祖长; 孙怡宁; 金艳; 张勤良

    2012-01-01

    目的:评估一款国产热固耦合式超声骨强度仪的可重复性和有效性.方法:选择11名志愿者,用该仪器测得右跟骨的两个超声参数,分别是超声速度(SOS)和宽带超声衰减(BUA),计算每个参数的变异系数均方根百分比(CVRMS%),评估该仪器的短期可重复性;选择18名志愿者,用类似的方法评估该仪器的中期可重复性;选择29名志愿者,用双能X线吸收法(DEXA)测量腰椎骨密度(BMD),并与用该仪器测得的跟骨SOS,BUA值进行相关性分析,评估该仪器的有效性.结果:①超声参数SOS,BUA的短期CVRMS%分别为0.30,4.24;中期CVRMS%分别为0.41,4.20.②SOS与腰椎BMD的相关系数r=0.486(P< 0.01),BUA与腰椎BMD的相关系数r=0.629(P< 0.01).结论:与国际主流定量超声(QUS)检测仪器相比,热同耦合式超声骨强度仪具有较高的可重复性和准确性,可用于临床骨质状况评估.%Objective: To evaluate the repeatability and correlation of warm-air and solid coupled mode ultrasound bone strength device made in China.Method: Eleven and eighteen volunteers' right calcaneus ultrasound parameters, speed of sound (SOS) and broad-band ultrasound attenuation (BUA), were detected with the device, percentages of root-mean square of coefficient of variation (CVrms%) of ultrasound parameters were calculated respectively, and used to assess the short- and middle-term repeatability of the device; 29 volunteers' right calcaneus ultrasound parameters (SOS, BUA) were de-tected with the device and bone mineral density (BMD) of lumbar spine were detected with dual energy X-ray absorptiometry (DEXA).Result: ?The short-term CVRMs% were 4.24% for BUA, and 0.30% for SOS; the middle-term CVRms% were 4.20% for BUA, and 0.41% for SOS. ?The correlations between BMD of lumbar spine were 0.629 (P<0.01) for BUA and 0.486 (P<0.01) for SOS.Conclusion: Compared to international top-grade quantitative ultrasound(QUS) testing device, the warm-air and solid coupled

  16. Commitee III.1 Ultimate Strength

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    1997-01-01

    This report addresses the subject of ductile collapse of ships and offshore structures and their components due to buckling and excessive yielding under overload conditions. Consideration is given to load-deflection predictions for components with fabrication imperfections and in-service damage a...... to the ultimate strength and post-ultimate behaviour of structural systems in order to identify the reserve strength. The effect of uncertainties in the modelling on the strength predictions is highlighted in two design examples....

  17. Air Pollution.

    Science.gov (United States)

    Air quality is affected by many types of pollutants that are emitted from various sources, including stationary and mobile. These sources release both criteria and hazardous air pollutants, which cause health effects, ecological harm, and material damage. They are generally categ...

  18. Grain boundary strength as point defect sink strength

    International Nuclear Information System (INIS)

    Sink strength of spherical grain boundary as an absolutely absorbing surface and as finite thickness wall consisting of the edge dislocations are considered. The values of the grain boundary sink strength are shown to be critically dependent on the point defect recombination degree

  19. Overview to Strength Development and Strength Trainings in Children

    Directory of Open Access Journals (Sweden)

    Mesut Hekim

    2015-08-01

    Full Text Available There are some important phases within psychomotor development process in children. Periods of movements related to sport appear in this phases. In this phase which contains 7-12 age period in children, a significant increment occurs in the physical and motoric development levels of children. Physical and motoric developments are supported by directing children in this age group to sport. In a plenty of studies, it was stated that participating to sports in children supports motoric features and physical development. Strength is one of the most important motoric features which develop via participating to sports. Children strength development is effected at positive direction by adaptation exercise made to support strength development. Psychomotor development basis are considered to obtain the best efficiency from workouts aimed strength development in children and to remove risks to be generate any injury/disability. In this research, strength development, contributions of participating in sports to strength development, strength training in children and children responses to strength training were all emphasized.

  20. Airborne field strength monitoring

    Directory of Open Access Journals (Sweden)

    J. Bredemeyer

    2007-06-01

    Full Text Available In civil and military aviation, ground based navigation aids (NAVAIDS are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000 by the International Civil Aviation Organization (ICAO. One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz, the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA accelerated method of moments (MoM using a complex geometric model of the aircraft. First results will be presented in this paper.

  1. Corrosion fatigue of high strength fastener materials in seawater

    Science.gov (United States)

    Tipton, D. G.

    1983-01-01

    Environmental effects which significantly reduce the fatigue life of metals are discussed. Corrosion fatigue is a major concern in the engineering application of high strength fasteners in marine environments. The corrosion fatigue failure of an AISI 41L4O high strength steel blade to hub attachment bolt at the MOD-OA 200 kW wind turbine generator was investigated. The reduction of fatigue strength of AISI 41L4O in marine environments and to obtain similar corrosion fatigue data for candidate replacement materials was studied. The AISI 4140, PH 13-8Mo stainless steel, alloy 718 and alloy MP-35N were tested in axial fatigue at a frequency of 20 Hz in dry air and natural seawater. The fatigue data are fitted by regression equations to allow determination of fatigue strength for a given number of cycles to failure.

  2. Loading Conditions and Longitudinal Strength

    DEFF Research Database (Denmark)

    Sørensen, Herman

    1995-01-01

    Methods for the calculation of the lightweight of the ship.Loading conditions satisfying draught, trim and intact stability requirements and analysis of the corresponding stillwater longitudinal strength.......Methods for the calculation of the lightweight of the ship.Loading conditions satisfying draught, trim and intact stability requirements and analysis of the corresponding stillwater longitudinal strength....

  3. Ultimate Strength, Committee III.1

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup; Estefan, S.; Fasano, E.;

    2003-01-01

    Concern for the ductile of ships and offshore structures and their structural components under ultimate conditions. Attention shall be given to the influence of fabrication imperfections and inservice damage and degradation on reserve strength. Uncertainties in strength models for design shall be...

  4. Muscle strength in myasthenia gravis

    DEFF Research Database (Denmark)

    Cejvanovic, S; Vissing, J

    2014-01-01

    related to disease duration or gender. The aim of this study was to quantify the strength of patients with MG and investigate whether it is related to disease duration. METHODS: Eight muscle groups were tested by manual muscle testing and with a hand-held dynamometer in 38 patients with generalized MG and...... 37 healthy age- and gender-matched controls. The disease duration was recorded and compared with strength measures. RESULTS: On average, muscle strength was decreased by 28% compared with controls (P<0.01). Repeated strength measures in individual patients did not differ, suggesting that the muscle...... force reported was not subject to fatigue, but reflected fixed weakness. The male patients showed a greater reduction in muscle force in all eight muscle groups than women with MG (60% vs 77% of normal, P<0.05). In both men and women with MG, strength in shoulder abductors was most affected (51% vs 62...

  5. Remolded Undrained Strength of Soils

    Institute of Scientific and Technical Information of China (English)

    HONG Zhen-shun(洪振舜); LIU Han-long(刘汉龙); NEGAMI Takehito

    2003-01-01

    Extensive data of undrained shear strength for various remolded soils are compiled to normalize the remolded undrained strength. Remolded soils have a wide spectrum of liquid limits ranging from 25% to 412%. It is found that the remolded undrained strength is a function of water content and liquid limit. Furthermore, a simple index designated as normalized water content w* is introduced for normalizing remolded undrained strength for various soils. The normalized water content w* is the ratio of water content to liquid limit. The relationship between the remolded undrained strength and the normalized water content can be expressed by a simple equation. The new simple equation is not only valuable theoretically for helping in assessing the in-situ mechanical behavior, but also useful to ocean engineering practice.

  6. Thin air

    OpenAIRE

    Jasanoff, Sheila

    2013-01-01

    Clearing the air How do we grasp the air? Without Michel Callon’s guidance, I might never have asked that question. Years ago, when I first entered environmental law practice, I took it for granted that problems such as air pollution exist “out there” in the real world for science to discover and law to fix. It is a measure of Callon’s influence that I understand the law today as a metaphysical instrument, no less powerful in its capacity to order nature than the tools of the ancient oracular...

  7. Mechanical properties of Concrete with SAP. Part I: Development of compressive strength

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede

    compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c <0.40) and moderate SAP additions, SAP increases the compressive strength at later ages (from 3 days after casting and onwards...

  8. Air Pollution

    Science.gov (United States)

    ... to a close in June 2013 when the company, Conscious Clothing, was awarded the My Air grand ... Page Options: Request Translation Services Facebook Twitter LinkedIn Google+ Reddit Email Evernote More Increase Font Size Decrease ...

  9. The strength and failure of silica optical fibers

    International Nuclear Information System (INIS)

    The mechanical strength and failure behavior of conventional and microstructured silica optical fibers was investigated using a tensile test and fracture mechanics and numerical analyses. The effect of polymer coating on failure behavior was also studied. The results indicate that all these fibers fail in a brittle manner and failure normally starts from fiber surfaces. The failure loads observed in coated fibers are higher than those in bare fibers. The introduction of air holes reduces fiber strength and their geometrical arrangements have a remarkable effect on stress distribution in the longitudinal direction. These results are potentially useful for the design, fabrication and evaluation of optical fibers for a wide range of applications.

  10. EUROPEAN URBANIZATION – BETWEEN STRENGTHS AND RISKS

    Directory of Open Access Journals (Sweden)

    Marcela Danu

    2014-01-01

    Full Text Available On the European continent, urban population, representing a significant segment of the market, with features specific to a particular model of purchase, consumption, lifestyle, etc. , has the potential for growth. The possible effects of this increase (strengths or risks, include: increasing opportunities for employment, increasing level and structure of demand for consumer goods and, in conjunction, of the level and structure of supply, raising of the standard of living, changing requirements and personal taste level population, increased interaction, socializing, psycho-social conversions on the recently urbanised population as well as for the people there, etc. but also the increase in demand for land areas intended for dwellings, commercial premises and hence reducing spaces with vegetation, increasing the degree of concentration of the population in a small grounds, effects on air quality, etc. This study highlights dynamic and interdependent effects of European urbanization on the human population, businesses, and the environment.

  11. Strength Degradation of Gfrp Bars

    OpenAIRE

    Bhise, Vikrant Sudhakar

    2002-01-01

    The primary objective of this research was to examine the strength degradation of Glass Fiber Reinforced Polymer (GFRP) bars at high temperature and alkalinity and determine if an Arrhenius type relationship can be used as a means of projecting life. The work done includes a thorough literature review, experiments and development of strength prediction models. The experimental work involves exposure of GFRP bars incased in cement mortar to lime-water solution at 30, 45 and 57°C. Overall 100 ...

  12. Impact strength of reactor graphite

    International Nuclear Information System (INIS)

    Dose dependences of impact strength of reactor graphite irradiated with neutrons at 340-360, 420-460 and 620-800 K by the fluence of up to 1.3x1022 cm-2 are plotted. It is pointed out that for the temperature range and fluence studied impact strength, as well as crack resistance, of reactor graphite exceed the same parameters of graphite before irradiation

  13. 78 FR 53133 - Meeting of the National Commission on the Structure of the Air Force

    Science.gov (United States)

    2013-08-28

    ... representatives from the Michigan Governor's office, local U.S. Air Force and Michigan National Guard leadership... Air Force, taking advantage of the unique strengths and capabilities of each; (c) ensures that...

  14. Characteristics of structural loess strength and preliminary framework for joint strength formula

    OpenAIRE

    Rong-jian LI; Jun-ding LIU; Yan, Rui; Zheng, Wen; Sheng-jun SHAO

    2014-01-01

    The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress ( line), and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests: the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural loes...

  15. Air surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Patton, G.W.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995).

  16. Analytical evaluation of the environment effect on creep rupture strength

    International Nuclear Information System (INIS)

    An analytical approach was made in evaluating semi-quantitatively the effect of environment on rupture strength of materials. In the analysis the zone formed in the material by reaction with the environment was assumed to bear the applied load as one of the strength members. In calculations a law of mixtures of creep strength and the linear damage rule were applied. In the modeling of the load bearing by the composite structure of the environment-affected and intact zones, both parallel and series models were considered to formulate the equations. The equation for the parallel-loaded model was properly adopted in explaining semi-quantitatively the case of Incoloy alloy 800 crept in air, which was strengthened with the layer formed by nitrization. The equation for the serially loaded model was more successfully adopted to the evaluation of the rupture strength of dissimilar weld joints. The latter was also considered to be potentially adoptable to the problems of the effect of specimen size and shape on rupture strength, which had been often taken into account in evaluating the environment effect. For application of the developed method, examination was made to the possible decrease in rupture strength of Hastelloy alloy XR in long term tests by the formation of Cr depleted zone due to oxidation in HTGR impure helium, and the results were compared with the values obtained by experiments. (author)

  17. Healthy Air Outdoors

    Science.gov (United States)

    ... lung.org > Our Initiatives > Healthy Air > Outdoor Healthy Air Outdoors The quality of the air we breathe ... families and can even shorten their lives. Outdoor Air Pollution and Health Outdoor air pollution continues to ...

  18. Air quality

    International Nuclear Information System (INIS)

    This chapter of the 'Assessment of the state of the environment in Lebanon' describes the air quality and identifies the most important air quality issues. Baseline information about the factors affecting dispersion and the climate of Lebanon presents as well and overall estimation of total emissions in Lebanon. Emissions from vehicles, electricity and power plants generation are described. Industrial emitters of air pollutants are described for each kind of industry i.e.cement plants, Selaata fertilizer factory, sugar-beet factory, refineries and for those derived from the use of leaded fuel . Impact of economic and human activities on air quality in Lebanon (especially in Beirut and Tripoli) are quantified by quantities of CO2, SO2, NOx, total suspended particulates(TSP), deposition and their environmental effects on health. In abscence of emissions monitoring, data available are expressed in terms of fuel use, output and appropriate empirical factors, national output and workfores sizes. Finally key issues and some potential mitigation /management approaches are presented

  19. Degradation of permeability resistance of high strength concrete after combustion

    Institute of Scientific and Technical Information of China (English)

    Min LI; Hongtao KAO; Chunxiang QIAN

    2008-01-01

    To evaluate the remaining durability of con-crete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (Dc), water permeability coef-ficient (Dw) and air permeability coefficient (Da). The experiment results show that all three permeability coeffi-cients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation tem-perature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and per-meability, the remaining durability of concrete materials after combustion is appropriately evaluated.

  20. Air flotation treatment of salmon processing waste water

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper discusses methods for the reduction of the pollution strength of salmon processing waste water. Past research has indicated the success of air pressure...

  1. Oscillator strengths for Be I

    Energy Technology Data Exchange (ETDEWEB)

    Ates, Sule, E-mail: suleates@selcuk.edu.tr; Oezarslan, Selma; Celik, Gueltekin; Taser, Mehmet

    2012-07-15

    The electric dipole oscillator strengths for lines between some singlet and triplet levels have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory for Be I. In the calculations both multiplet and fine structure transitions are studied. We employed both the numerical Coulomb approximation method and numerical non-relativistic Hartree-Fock wavefunctions for expectation values of radii. The necessary energy values have been taken from experimental energy data in the literature. The calculated oscillator strengths have been compared with available theoretical results. A good agreement with the results in the literature has been obtained.

  2. Measuring the Strength of Mice

    OpenAIRE

    Deacon, Robert M.J.

    2013-01-01

    Kondziela7 devised the inverted screen test and published it in 1964. It is a test of muscle strength using all four limbs. Most normal mice easily score maximum on this task; it is a quick but insensitive gross screen, and the weights test described in this article will provide a finer measure of muscular strength. There are also several strain gauge-based pieces of apparatus available commercially that will provide more graded data than the inverted screen test, but their cost may put them ...

  3. Determination of the air attenuation and electronic loss for the free air concentric cylinders ionization chamber; Determinacao da atenuacao do ar e perda eletronica para a camara de ionizacao de ar livre de cilindros concentricos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Hebert Pinto Silveira de

    2010-07-01

    Along the latest years, the LNMRI has been proceeding a continuous research work with a concentric cylinders type free air ionizing chamber (VICTOREEN, model 481), aiming to establish it as a new national standard, and, as a consequence, replace the worldwide accepted secondary standard, calibrated by PTB. Taking into account that the absolute determination of kerma in air with a free air ionizing chamber implies the acquirement of a number of correction factors. The main objective of the present work comprises the determination of the two factors, specifically, electronic loss (k{sub e}) and air attenuation (k{sub a}). The correction factors were obtained through mammography qualities reference spectrum, using Monte Carlo simulation method. The Penelope code was used in the simulation procedures. Simulations took place in two stages, the acquirement of specters related to the qualities of interest (mammography) with the x ray tube (Pantak, model HF160 e Panalytical, model XRF window), and the free-air ionization chamber. The data were compared to those related to the BIPM chamber, to electronic loss were not detected. The comparison between air attenuation factors was obtained data bellow 0.13%. (author)

  4. Royal Danish Air Force. Air Operations Doctrine

    DEFF Research Database (Denmark)

    Nørby, Søren

    This brief examines the development of the first Danish Air Force Air Operations Doctrine, which was officially commissioned in October 1997 and remained in effect until 2010. The development of a Danish air power doctrine was heavily influenced by the work of Colonel John Warden (USAF), both...... through his book ”The Air Campaign” and his subsequent planning of the air campaign against Iraq in 1990-1991. Warden’s ideas came to Denmark and the Danish Air Force by way of Danish Air Force students attending the United States Air Force Air University in Alabama, USA. Back in Denmark, graduates from...... the Air University inspired a small number of passionate airmen, who then wrote the Danish Air Operations Doctrine. The process was supported by the Air Force Tactical Command, which found that the work dovetailed perfectly with the transformation process that the Danish Air Force was in the midst of...

  5. Air pollution

    International Nuclear Information System (INIS)

    Australian cites experience a number of current and emerging air pollution problems. Concentrations of traditional primary pollutants such as CO, lead and dust have fallen in recent years as a consequence of air pollutant control measures, and the widespread introduction of lead-free petrol. However, recommended guidelines for ozone, the principal component of photochemical smog, are regularly exceeded in major capital cities in the summer months. In addition, it is predicted that extensive urban expansion will lead to much greater dependence on the motor vehicle as the primary means of transportation. Effects of air pollution are felt at a variety of scales. Traditionally, concerns about gaseous and particulate emissions from industrial and vehicular sources were focused on local impacts due to exposure to toxic species such as CO and lead. As noted above, concentrations of these pollutants have been reduced by a variety of control measures. Pollutants which have effects at a regional scale, such as photochemically-produced ozone, and acidic gases and particles have proved more difficult to reduce. In general, these pollutants arc not the result of direct emissions to atmosphere, but result from complex secondary processes driven by photochemical reactions of species such as NO2 and aldehydes. In addition, global effects of gaseous and particulate emissions to the atmosphere have received significant recent attention, concentrations of atmospheric CO2 with predicted impacts on global climate, and ozone depletion due to anthropogenic emissions of chlorine-containing chemicals are the two major examples. Combustion processes from petrol- and diesel-fuelled vehicles, make major contributions to air pollution, and the magnitude of this contribution is discussed in this article

  6. The Strengths of Black Families.

    Science.gov (United States)

    Hill, Robert B.

    This report identifies and analyzes five strengths of black families: adaptability roles, strong kinship bonds, strong work orientation, strong religious orientation, and achievement orientation. These five characteristics have been functional for the survival, advancement, and stability of black families. Most discussions of black families tend…

  7. An interlaminar tension strength specimen

    Science.gov (United States)

    Jackson, Wade C.; Martin, Roderick H.

    1992-01-01

    This paper describes a technique to determine interlaminar tension strength, sigma(sub 3c) of a fiber reinforced composite material using a curved beam. The specimen was a unidirectional curved beam, bent 90 degrees, with straight arms. Attached to each arm was a hinged loading mechanism which was held by the grips of a tensile testing machine. Geometry effects of the specimen, including the effects of loading arm length, inner radius, thickness, and width, were studied. The data sets fell into two categories: low strength corresponding to a macroscopic flaw related failure and high strength corresponding to a microscopic flaw related failure. From the data available, the loading arm length had no effect on sigma(sub 3c). The inner radius was not expected to have a significant effect on sigma(sub 3c), but this conclusion could not be confirmed because of differences in laminate quality for each curve geometry. The thicker specimens had the lowest value of sigma(sub 3c) because of poor laminate quality. Width was found to affect the value of sigma(sub 3c) only slightly. The wider specimens generally had a slightly lower strength since more material was under high stress, and hence, had a larger probability of containing a significant flaw.

  8. IMPACT OF COOKING HOMOGENEITY ON PULP STRENGTH PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Bofeng Mao

    2004-01-01

    Cooking homogeneity of kraft pulping can have significant impact on pulp strength properties. We have studied cooking homogeneity of two kraft digesters within Stora Enso. One of the digesters is a one-vessel hydraulic continuous digester (digester A)and the other one is a two-vessel vapor/liquor phase continuous digester (digester B). They are located in the same mill and use the same softwood chip quality. Due to the differences in chip pre-steaming and cooking facilities and conditions, significant differences in pulp strength properties, reject contents and kappa variations have been found between the pulps produced in the two digesters. Digester A has a modem chip bin with efficient pre-heating and air removal, whereas digester B has poor chip pre-steaming conditions. Our strength delivery studies show that although the two digesters produce pulps with the same kappa number and viscosity, the pulp produced in digester A has about 20% higher strength delivery, l%-unit (based on wood) lower reject content and lower kappa variations based on FTIR spectra analysis on pulp sheet than the pulp produced in digester B.Results of the studies indicate that more homogeneous cooking, i.e., lower lignin/kappa variation in the fibers, leads to improved pulp strength properties. Efficient chip pre-steaming is important/essential for achieving homogeneous cooking. Rebuilding the equipment for improving chip pre-steaming conditions of digester B is to be carried out.

  9. Air filtration and indoor air quality

    DEFF Research Database (Denmark)

    Bekö, Gabriel

    2006-01-01

    Demands for better indoor air quality are increasing, since we spend most of our time indoors and we are more and more aware of indoor air pollution. Field studies in different parts of the world have documented that high percentage of occupants in many offices and buildings find the indoor air...... decent ventilation and air cleaning/air filtration, high indoor air quality cannot be accomplished. The need for effective air filtration has increased with increasing evidence on the hazardous effects of fine particles. Moreover, the air contains gaseous pollutants, removal of which requires various air...... cleaning techniques. Supply air filter is one of the key components in the ventilation system. Studies have shown that used ventilation filters themselves can be a significant source of indoor air pollution with consequent impact on perceived air quality, sick building syndrome symptoms and performance...

  10. A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy

    Directory of Open Access Journals (Sweden)

    Arshed Waheed

    2010-01-01

    Full Text Available An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained within a range of 0% to ±1.7% for the PTW UNIDOS dosimetry system. This means that although the recommended method is in-water calibration, under exceptional circumstances, in-air calibration may be used as well.

  11. The Effects of Steel Fibre on the Mechanical Strength and Durability of Steel Fibre Reinforced High Strength Concrete (SFRHSC Subjected to Normal and Hygrothermal Curing

    Directory of Open Access Journals (Sweden)

    Velayutham G.

    2014-03-01

    Full Text Available This paper presents the experimental investigation into the mechanical strength and durability of steel fibre high strength concrete (SFHSC. In the experimental investigation, the properties of the steel fibre high strength concrete were assessed through two types of curing regimes, the normal water curing and the hygrothermal curing treatment, with the results of the tests being taken at 7 days and 7 days + 24 hours. The steel fibres were added at volume fractions of 0.5%, 1.0%, 1.5%, 2.0% and 3.0%. The tests that were performed for the mechanical strength and durability were the compressive and flexural strength test, the modulus of elasticity test, the ultrasonic pulse velocity test, the water absorption test, the air permeability test and the porosity test. The compressive and flexural strength of the steel fibre high strength concrete reached their maximum of 70.7 MPa and 11.45 MPa, respectively during normal curing for the 3.0% volume fraction of steel fibre. The experimental results of this study indicate that the inclusion of steel fibres enhances the mechanical strength of high strength concrete cured in normal water curing as compared to the hygrothermal curing treatment.

  12. Compressive strength after blast of sandwich composite materials.

    Science.gov (United States)

    Arora, H; Kelly, M; Worley, A; Del Linz, P; Fergusson, A; Hooper, P A; Dear, J P

    2014-05-13

    Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styrene-acrylonitrile (SAN) polymer closed-cell foam core are the primary composite system evaluated. Glass-fibre-reinforced polymer (GFRP) composite skins were also included for comparison in a comparable sandwich configuration. Full-scale blast experiments were conducted, where 1.6×1.3 m sized panels were subjected to blast of a Hopkinson-Cranz scaled distance of 3.02 m kg(-1/3), 100 kg TNT equivalent at a stand-off distance of 14 m. This explosive blast represents a surface blast threat, where the shockwave propagates in air towards the naval vessel. Hopkinson was the first to investigate the characteristics of this explosive air-blast pulse (Hopkinson 1948 Proc. R. Soc. Lond. A 89, 411-413 (doi:10.1098/rspa.1914.0008)). Further analysis is provided on the performance of the CFRP sandwich panel relative to the GFRP sandwich panel when subjected to blast loading through use of high-speed speckle strain mapping. After the blast events, the residual compressive load-bearing capacity is investigated experimentally, using appropriate loading conditions that an in-service vessel may have to sustain. Residual strength testing is well established for post-impact ballistic assessment, but there has been less research performed on the residual strength of sandwich composites after blast. PMID:24711494

  13. Combining strength and toughness in ultrahigh strength steel

    Science.gov (United States)

    Wang, L. D.; Jiang, L. Z.; Zhu, M.; Liu, X.; Zhou, W. M.; Li, Y.

    2004-08-01

    The main objective of this investigation is to examine the effects of a new technique, double-ageing, on the microstructure and mechanical properties of the ultrahigh strength steel Aermet 100. Under the condition of double-ageing, there is no apparent decrease in the steel strength. However, the impact fatigue life can be prolonged by 35.5% and the dynamic fracture toughness raised by 22.6% by this technique compared with normal ageing. Based on the observation of the microscopic structure, the physical mechanism of prolongation of fatigue life and enhancement of the stability of the reverted austenite is analysed further. The results show that this new technique is a breakthrough in optimally combining the strength and toughness of Aermet 100 steel. In light of the current understanding of this subject, the toughness of the reverted austenite formed at the time of heat preservation at the higher temperature of the double-ageing process increases drastically. Moreover, during the treatment at the lower temperature of the double-ageing process, the carbon separating from the martensitic ferrite of Aermet 100 steel will diffuse into the reverted austenite, resulting in a decrease of the brittleness of the martensite and an increase of the stability of the reverted austenite.

  14. Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

    OpenAIRE

    Huai-shuai Shang; Wei-qun Cao; Bin Wang

    2014-01-01

    Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles...

  15. R9 Air Districts

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Region 9 Air Districts layer is a compilation of polygons representing the California Air Pollution Control and Air Quality Management Districts, Arizona Air...

  16. AirData

    Data.gov (United States)

    U.S. Environmental Protection Agency — The AirData site provides access to yearly summaries of United States air pollution data, taken from EPA's air pollution databases. AirData has information about...

  17. California Air Basins

    Data.gov (United States)

    California Department of Resources — Air ResourcesCalifornia Air Resources BoardThe following datasets are from the California Air Resources Board: * arb_california_airbasins - California Air BasinsThe...

  18. Hazardous Air Pollutants

    Science.gov (United States)

    ... Facebook Twitter Google+ Pinterest Contact Us Hazardous Air Pollutants Hazardous air pollutants are those known to cause ... protect against adverse environmental effects. About Hazardous Air Pollutants What are hazardous air pollutants? Health and Environmental ...

  19. Optical oscillator strengths for carbon

    International Nuclear Information System (INIS)

    An analytic atomic independent particle model adjusted to experimental single-particle energy levels is used to generate wave functions for the excited states of carbon. Using these wave functions in conjunction with the Born approximation and the Russell-Saunders LS coupling scheme, we calculate optical oscillator strengths for various transitions from the 2p2(3P0) ground state. The results are compared to experiment and other calculations. (orig.)

  20. Password crackers and passphrase strength

    OpenAIRE

    Weber, Uroš

    2015-01-01

    The thesis describes the role of passwords to protect unauthorized access to our acounts (and consequently also our data). Technology is constantly evolving, thereby there is also rapid developement of security mechanisms for protection of passwords, as well as new forms of vulnerability for passwords protection. The main purpose of this thesis is to raise awareness of choosing strong passwords and present the application, which can show strength of our password. We will study known p...

  1. Ultra high strength in steel.

    Directory of Open Access Journals (Sweden)

    V. R. Parameswaran

    1962-07-01

    Full Text Available Very high strength levels in steel, not obtained by conventional methods of hardening by quenching and low temperature tempering, are obtained by mew hardening techniques involving the thermal-mechanical treatment of metastable austenite.The earlier attempts on such hardening techniques and the development of new processes such as 'Ausforming' investigated in the Ford Motor Company Research Laboratories and ''Maraging'' developed and patented by the International Nickel Company (MondLimited, are briefly reviewed here.

  2. Ideal Strength of Doped Graphene

    OpenAIRE

    Woo, S. J.; Son, Young-Woo

    2012-01-01

    While the mechanical distortions change the electronic properties of graphene significantly, the effects of electronic manipulation on its mechanical properties have not been known. Using first-principles calculation methods, we show that, when graphene expands isotropically under equibiaxial strain, both the electron and hole doping can maintain or improve its ideal strength slightly and enhance the critical breaking strain dramatically. Contrary to the isotropic expansions, the electron dop...

  3. Conditioned Reinforcement and Response Strength

    OpenAIRE

    Shahan, Timothy A

    2010-01-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned...

  4. The moments of strength functions

    International Nuclear Information System (INIS)

    In this paper we show that a moment of order n of the strength function is determined by the same order of the Brillouin-Wigner perturbative expansion. This fact is used to study the second moment for single-particle and collective excitations in the framework of nuclear field theory. We discuss the relationship of the second moment with the spreading width of the giant isovector M1 resonances in 208Pb. (orig.)

  5. Strength scaling in fiber composites

    Science.gov (United States)

    Kellas, Sotiris; Morton, John

    1991-01-01

    A research program was initiated to study and isolate the factors responsible for scale effects in the tensile strength of graphite/epoxy composite laminates. Four layups were chosen with appropriate stacking sequences so as to highlight individual and interacting failure modes. Four scale sizes were selected for investigation including full scale size, 3/4, 2/4, and 1/4, with n = to 4, 3, 2, and 1, respectively. The full scale specimen sizes was 32 piles thick as compared to 24, 16, and 8 piles for the 3/4, 2/4, and 1/4 specimen sizes respectively. Results were obtained in the form of tensile strength, stress-strain curves and damage development. Problems associated with strength degradation with increasing specimen sizes are isolated and discussed. Inconsistencies associated with strain measurements were also identified. Enchanced X-ray radiography was employed for damage evaluation, following step loading. It was shown that fiber dominated layups were less sensitive to scaling effects compared to the matrix dominated layups.

  6. Investigation of Dosimetric Parameters of $^{192}$Ir MicroSelectron v2 HDR Brachytherapy Source Using EGSnrc Monte Carlo Code

    CERN Document Server

    Naeem, Hamza; Zheng, Huaqing; Cao, Ruifen; Pei, Xi; Hu, Liqin; Wu, Yican

    2016-01-01

    The $^{192}$Ir sources are widely used for high dose rate (HDR) brachytherapy treatments. The aim of this study is to simulate $^{192}$Ir MicroSelectron v2 HDR brachytherapy source and calculate the air kerma strength, dose rate constant, radial dose function and anisotropy function established in the updated AAPM Task Group 43 protocol. The EGSnrc Monte Carlo (MC) code package is used to calculate these dosimetric parameters, including dose contribution from secondary electron source and also contribution of bremsstrahlung photons to air kerma strength. The Air kerma strength, dose rate constant and radial dose function while anisotropy functions for the distance greater than 0.5 cm away from the source center are in good agreement with previous published studies. Obtained value from MC simulation for air kerma strength is $9.762\\times 10^{-8} \\textrm{UBq}^{-1}$and dose rate constant is $1.108\\pm 0.13\\%\\textrm{cGyh}^{-1} \\textrm{U}^{-1}$.

  7. Guided-wave Brillouin scattering in air

    CERN Document Server

    Renninger, William H; Rakich, Peter T

    2016-01-01

    Here we identify a new form of optomechanical coupling in gas-filled hollow-core fibers. Stimulated forward Brillouin scattering is observed in air in the core of a photonic bandgap fiber. A single resonance is observed at 35 MHz, which corresponds to the first excited axial-radial acoustic mode in the air-filled core. The linewidth and coupling strengths are determined by the acoustic loss and electrostrictive coupling in air, respectively. A simple analytical model, refined by numerical simulations, is developed that accurately predicts the Brillouin coupling strength and frequency from the gas and fiber parameters. Since this form of Brillouin coupling depends strongly on both the acoustic and dispersive optical properties of the gas within the fiber, this new type of optomechanical interaction is highly tailorable. These results allow for forward Brillouin spectroscopy in dilute gases, could be useful for sensing and will present a power and noise limitation for certain applications.

  8. Effects of political institutions on air quality

    International Nuclear Information System (INIS)

    We empirically test existing theories on the provision of public goods, in particular air quality, using data on sulfur dioxide (SO2) concentrations from the Global Environment Monitoring Projects for 107 cities in 42 countries from 1971 to 1996. The results are as follows: First, we provide additional support for the claim that the degree of democracy has an independent positive effect on air quality. Second, we find that among democracies, presidential systems are more conducive to air quality than parliamentary ones. Third, in testing competing claims about the effect of interest groups on public goods provision in democracies we establish that labor union strength contributes to lower environmental quality, whereas the strength of green parties has the opposite effect. (author)

  9. Improved free-air ionization chamber for the measurement of X-rays

    International Nuclear Information System (INIS)

    Based on an original design by F. H. Attix, an improved free-air ionization chamber was constructed at the National Radiation Standard Laboratory of the Institute of Nuclear Energy Research (INER, Taiwan), as the primary standard for x-ray generated at energy levels between 50 keV and 300 keV. Various improvements were made to the Attix design, including modifications of the chamber structure and the measurement technique. The changes include: a three-section design with fixed central cylinder; thickening of the shielding box; a circuitous mechanism for the operational handle, to avoid unwanted scattering; a ruler mechanism to provide fine position control; and increased thickness of the aluminium wall of the chamber. After initial experimental verification, a comparison with the National Institute of Standards and Technology (NIST, USA) using a transfer standard chamber yielded differences in calibration factors of less than 1 %. In addition, the overall uncertainty for the x-ray measurement in terms of air kerma is less than 1 % at the 95 % confidence level. These results indicate that the improved free-air ionization chamber can serve as a primary standard at the NRSL. (authors)

  10. Indoor air quality environmental information handbook: Building system characteristics

    International Nuclear Information System (INIS)

    This manual, the third in a series, focuses on residential building system characteristics and their effects on indoor air quality. The manual addresses: residential indoor air pollutants by source, indoor concentrations, health effects, source control and mitigation techniques, standards and guidelines; building system characteristics of air exchange, pollutant source strength, residence volume, site characteristics, structural design, construction, and operation, infiltration and ventilation system, building occupancy; and monitoring methods

  11. Pressurized air supply device

    International Nuclear Information System (INIS)

    Ventilation air-conditioning facilities in a nuclear reactor building are adapted to suck clean external air not containing radioactivity through air supply filters disposed at an air intake port of the nuclear reactor building by means of an air supply blower and then supply the sucked air through an air supply duct and an air supply port to the inside of the power plant. Futher, pipeways for supplying sucked air to a compressor is branched from the air supply duct, through which air is supplied to an air compressor for instrumentation and an air compressor used in the power plant. The air sucked and compressed in the air compressor for instrumentation is further supplied by way of pipeways for supplying air for instrumentation to air-actuated valves, instruments, etc. Further, air sucked and compressed in the air compressor used in the power plant is further supplied by way of air supply pipeways for the power plant to a reservoir, air mask, etc. By supplying clean compressed air in this way, operators exposure dose can be reduced. (T.M.)

  12. Dielectric strength of parylene HT

    International Nuclear Information System (INIS)

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness dC (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (FB) appear in the thickness range. For d ≥ dC, PA-HT films exhibit a decrease in the breakdown field following a negative slope (FB ∼ d−0.4), while for d C, it increases with increasing the thickness (FB ∼ d0.3). An optimal thickness doptim ∼ 5 μm corresponding to a maximum dielectric strength (FB ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in FB above dC is explained by the spherulites development, whereas its increase below dC is induced by the crystallites growth. An annealing of the material shows both an enhancement of FB and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below dC showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on FB for d ≥ dC

  13. Dielectric strength of parylene HT

    Energy Technology Data Exchange (ETDEWEB)

    Diaham, S., E-mail: sombel.diaham@laplace.univ-tlse.fr; Bechara, M.; Locatelli, M.-L.; Khazaka, R. [Université de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne-Bât. 3R3, F-31062 Toulouse Cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France); Tenailleau, C. [Université de Toulouse, UPS, Laboratoire CIRIMAT/LCMIE, 118 route de Narbonne-Bât. 2R1, F-31062 Toulouse Cedex 9 (France); Kumar, R. [Speciality Coating Systems, Inc. (SCS), Cookson Electronics, 7645 Woodland Drive, Indianapolis, Indiana 46278 (United States)

    2014-02-07

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness d{sub C} (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (F{sub B}) appear in the thickness range. For d ≥ d{sub C}, PA-HT films exhibit a decrease in the breakdown field following a negative slope (F{sub B} ∼ d{sup −0.4}), while for d < d{sub C}, it increases with increasing the thickness (F{sub B} ∼ d{sup 0.3}). An optimal thickness d{sub optim} ∼ 5 μm corresponding to a maximum dielectric strength (F{sub B} ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in F{sub B} above d{sub C} is explained by the spherulites development, whereas its increase below d{sub C} is induced by the crystallites growth. An annealing of the material shows both an enhancement of F{sub B} and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below d{sub C} showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on F{sub B} for d ≥ d{sub C}.

  14. Comparison of Remolded Shear Strength with Intrinsic Strength Line for Dredged Deposits

    Institute of Scientific and Technical Information of China (English)

    DENG Dong-sheng

    2007-01-01

    Chandler proposed the intrinsic strength line to correlate the undrained shear strength of samples one-dimensionally consolidated from slurry with the void index proposed by Burland. The undrained shear strength on the intrinsic strength line is different from the remolded undrained shear strength that is an important parameter for design and construction of land reclamation. The void index is used in this study for normalizing the remolded strength behavior of dredged deposits. A quantitative relationship between remolded undrained shear strength and void index is established based on extensive data of dredged deposits available from sources of literature. Furthermore, the normalized remolded undrained shear strength is compared with intrinsic strength line. The comparison result indicates that the ratio of undrained shear strength on the intrinsic strength line over remolded undrained shear strength increases with an increase in applied consolidated stress.

  15. Crushing Strength of Aluminum Honeycomb with Thinning Cell Wall

    Science.gov (United States)

    Ogasawara, Nagahisa; Chiba, Norimasa; Kobayashi, Eiji; Kikuchi, Yuji

    To evaluate the crash safety of automobiles, various collision tests are performed by the auto industry. In the offset frontal collision test and the side collision test, the target is an aluminum honeycomb material which has thinning cell walls. In this study, based on the analyses of the shock absorption mechanism, a new crushing strength formula is proposed. First, load-displacement curves obtained from compression tests in quasi-static condition showed an almost linear relation between a thinning rate of cell walls and a crushing strength. Second, based on Wierzbicki's theory, a new formula was proposed, which can estimate a crushing strength of a honeycomb material with thinning wall. In addition, a correcting equation which considered an elastic deformation was also proposed. Third, parametric analyses were carried out with a FE model which can simulate a delamination between cell walls. The results obtained from the theory and FEM almost corresponded to each other for a wide range of the thinning rate. Fourth, impact tests were carried out, in which the weight was dropped freely at the speed used for the automobile tests. Those results almost agreed well with the sum of the theoretical crush strength and the inside air pressure.

  16. Analysis of Homogel Uniaxial Compression Strength on Bio Grouting Material

    Directory of Open Access Journals (Sweden)

    Kyungho Park

    2016-03-01

    Full Text Available This study analyzed uniaxial compression strength over time by preparing a homogel specimen from a bio grouting material, a cement-like form produced by environment-friendly microbial reactions. Among chemical grouting methods, the most commonly used method is the Labile Waterglass method. In this study, the homogel uniaxial compressive strength of Labile Waterglass (LW injection material and that of bio grouting material were measured and analyzed. In order to perform the experiment, a total of 10 types of grouting mixing ratios were prepared by a combination of different materials such as Ordinary Portland Cement, Micro Cement, Bio Grouting Material and Sodium Silicate. They were cured in the air, and their homogel uniaxial compression strengths were measured on days 1, 3, 7 and 28 Based on the test results, it was confirmed that the uniaxial strength of the specimen made with Bio Grouting Material, Ordinary Portland Cement and Micro Cement was increased by more than 30% than that of the specimen only used with Ordinary Portland Cement, as a result of hydrogen-released heat reaction between calcium carbonate, the main ingredient of the bio grouting material, and calcium silicate in the cement. This indicates that the use of 30% bio-grouting material instead of cement in the grouting can be a reasonable mixing ratio to save the use of cement, leading to reduction in CO2 emission.

  17. Electronic Correlation Strength of Pu

    DEFF Research Database (Denmark)

    Svane, A.; C. Albers, R.; E. Christensen, N.;

    2013-01-01

    A new electronic quantity, the correlation strength, is defined as a necessary step for understanding the properties and trends in strongly correlated electronic materials. As a test case, this is applied to the different phases of elemental Pu. Within the GW approximation we have surprisingly fo...... found a "universal" scaling relationship, where the f-electron bandwidth reduction due to correlation effects is shown to depend only upon the local density approximation (LDA) bandwidth and is otherwise independent of crystal structure and lattice constant....

  18. Lijiang: From Brand to Strength

    Institute of Scientific and Technical Information of China (English)

    Gao Wentian; Bai Yifeng

    2009-01-01

    @@ The tourism industry is facing unprecedented challenges after the financial crisis.During this "financial winter",how much influence has Lijiang's tourism,the one that has been the pillar industry of Lijiang and important economic growth point received? And how does the government of Lijiang deal with this? How to transform it from "Brand Lijiang" to "Strength Lijiang"? Member of National People's Congress,Lijiang's deputy secretary of municipal party committee,and Mayor Wang Junzheng accepted an exclusive interview with our reporter.

  19. Air movement and perceived air quality

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Kaczmarczyk, J.

    2012-01-01

    The impact of air movement on perceived air quality (PAQ) and sick building syndrome (SBS) symptoms was studied. In total, 124 human subjects participated in four series of experiments performed in climate chambers at different combinations of room air temperature (20, 23, 26 and 28 °C), relative...... humidity (30, 40 and 70%) and pollution level (low and high). Most of the experiments were performed with and without facially applied airflow at elevated velocity. The importance of the use of recirculated room air and clean, cool and dry outdoor air was studied. The exposures ranged from 60. min to 235....... min. Acceptability of PAQ and freshness of the air improved when air movement was applied. The elevated air movement diminished the negative impact of increased air temperature, relative humidity and pollution level on PAQ. The degree of improvement depended on the pollution level, the temperature and...

  20. Dept and field size dependence of ratios of mass energy absorption coefficient, water to air, for kilovoltage X ray dosimetry

    International Nuclear Information System (INIS)

    Values of the ratio of the mass energy absorption coefficient, water to air, (μ-baren/ρ)w,air, are required for insertion into the expression recommended for determining absorbed dose to water, Dw, in kilovoltage X ray beams using an air kerma calibrated ionization chamber. Values for both primary (i.e. free-in-air) spectra and spectra at depths within a water phantom have been calculated for low and medium energy X rays using the Monte Carlo method. These are [(μ-baren/ρ)w,air]p, for HVLs between 0.05 and 22 mm A1 (0.03 and 6 mm Cu), and (μ-baren(z, f)/ρ)w,air, for HVLs between 1 and 22 mm A1 (0.01 and 6 mm Cu), at depths (z) between 0 and 10 cm with circular field sizes (f) between 0.5 and 30 cm2 equivalent square. Primary spectra and the corresponding HVLs (in mm Cu or A1) were calculated using he programs of Birch and Marshall. X ray unit target angles and inherent/added filtrations were consistent with those used for the measured spectra of Seelentag et al. The EGS4 (Electron Gamma Shower version 4) Monte Carlo package was used to simulate photon transport within a water phantom through adaptation of the user code FLURZ. Monoenergetic μ-baren/ρ data were extracted from the work of Hubbell. It is evident that the first HVL is inadequate as a unique look-up parameter for (μ-baren/ρ)w,air. The variation of (μ-baren(z, f)/ρ)w,air with f and z is shown. The dependence of (μ-baren(z, f)/ρ)w,air on f is significant, especially for less than 10 cm square fields. The corresponding dependence on z is less critical. (author). 14 refs, 4 figs, 1 tab

  1. Verification of I-125 brachytherapy source strength for use in radioactive seed localization procedures.

    Science.gov (United States)

    Metyko, John; Erwin, William; Landsberger, Sheldon

    2016-06-01

    A general-purpose nuclear medicine dose calibrator was assessed as a potential replacement for a dedicated air-communicating well-type ionization chamber (brachytherapy source strength verification instrument) for (125)I seed source strength verification for radioactive seed localization, where less stringent accuracy tolerances may be acceptable. The accuracy, precision and reproducibility of the dose calibrator were measured and compared to regulatory requirements. The results of this work indicate that a dose calibrator can be used for (125)I seed source strength verification for radioactive seed localization. PMID:27015651

  2. Studies of the mortality of A-bomb survivors. 9. Mortality, 1950-1985: Part 1. Comparison of risk coefficients for site-specific cancer mortality based on the DS86 and T65DR shielded kerma and organ doses

    International Nuclear Information System (INIS)

    As a result of the reassessment of the A-bomb dosimetry, new (DS86) doses were calculated in 1986. In this paper, site-specific estimates of cancer mortality in the years 1950-1985, based on these new doses, are compared with those using the T65DR doses. The subjects of the study are 75,991 members of the Life Span Study sample for whom DS86 doses have been calculated. This reevaluation of the exposures does not change the list of radiation-related cancers. Most differences in dose response between Hiroshima and Nagasaki are no longer significant with the DS86 doses. The dose-response curve is closer to linear with the DS86 than the T65DR doses even for leukemia in the entire dose range, though, statistically, many other models cannot be excluded. However, in the low-dose range, the risk of leukemia remains nonlinear. Assuming a linear model at an RBE of 1, and using organ-absorbed doses, the risk coefficients derived from the two dosimetries are very similar, whereas those based on shielded kerma are about 40% higher with the new dosimetry. If RBE values larger than 1 are assumed, the disparity between the two dosimetries increases because the neutron dose is much greater in the T65DR. At an RBE of 10, for the five specific cancers, i.e., female breast, colon, leukemia, lung, and stomach, the increase in excess number of deaths per 10(4) PYSv under the DS86 varies from 12% (colon) to 133% (female breast). The magnitude of the effects of such modifiers of radiation-induced cancer as age at time of bomb and sex do not differ between the two dose systems

  3. Three Important Advances in Engineering Strength Theories

    Institute of Scientific and Technical Information of China (English)

    YuMaohong; FanWen; MitustoshiYoshimine

    2003-01-01

    There are there great advances in the research on engineering strength theories in the latter half of the 20th Century. The first advance was the devel-opment of strength theory from the single-shear strength theory including the Tresca yield criterion and Mohr-Coulomb failure criterion to theoctahe-dral-shear strength theory; the second one was that from the octahedral-shear strength theory to the twin-shear strength theory; and the third wasthe theories from the single criteria to the unifiedstrength theory. These three advances are summa-rized in this paper. It is interesting and useful for re-searchers to choose an appropriate failure criterion in studying the strength of materials and struc-tures, for engineers to correctly use it and for stu-dents to understand strength theory.

  4. THE EFFECT OF 800 0C ON BOND STRENGTH OF CONCRETE WITH MINERAL ADMIXTURE

    Directory of Open Access Journals (Sweden)

    Ahmet COŞKUN

    2007-03-01

    Full Text Available The effect of high temperature (800 0C on the bond strength between concrete and rebar was investigated. In addition to concrete mixture with only portland cement, concrete mixtures with 10% silica fume and 15 % fly ash replacing cement by weight was prepared. Maximum aggregate size is as 16 mm. The 150×150×150 mm cube specimens were prepared for compressive strength and the 100×200 mm cylinder specimens were prepared for bond strength. The specimens were cured in air for 270 days after curing in water 20±2 °C for 28 days. After being heated to temperatures of 800 ºC, compressive strength and bond strength of concrete were tested. The results showed that specimens with silica fume always gave the highest values followed by those as specimens with fly ash and specimens without mineral admixtures irrespective of type and age of concrete and test methods.

  5. Strength distribution in commercial silicon carbide materials

    Science.gov (United States)

    Dutta, Sunil

    1988-01-01

    Four-point flexural strength testing has been conducted in order to establish the baseline strength and reliability of four different commercial SiC types, in conjunction with reliable Weibull modulus values. Average strength of the samples ranged from 380 to 482 MPa at room temperature and 307 to 470 MPa at 1370 C. The strength scatter reflects the effect of flaw variability, which must be minimized to improve reliability in sintered SiC.

  6. Air filtration and indoor air quality

    DEFF Research Database (Denmark)

    Bekö, Gabriel

    decent ventilation and air cleaning/air filtration, high indoor air quality cannot be accomplished. The need for effective air filtration has increased with increasing evidence on the hazardous effects of fine particles. Moreover, the air contains gaseous pollutants, removal of which requires various air...... contradictions should motivate manufacturers and researchers to develop new efficient filtration techniques and/or improve the existing ones. Development of low polluting filtration techniques, which are at the same time easy and inexpensive to maintain is the way forward in the future....

  7. Strengths and Satisfaction across the Adult Lifespan

    Science.gov (United States)

    Isaacowitz, Derek M.; Vaillant, George E.; Seligman, Martin E. P.

    2003-01-01

    Positive psychology has recently developed a classification of human strengths (Peterson & Seligman, in press). We aimed to evaluate these strengths by investigating the strengths and life satisfaction in three adult samples recruited from the community (young adult, middle-aged, and older adult), as well as in the surviving men of the Grant study…

  8. Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

    International Nuclear Information System (INIS)

    A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching

  9. Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, P.S. [Ordnance Development Centre, Metal and Steel Factory, Ishapore 743 144 (India); Ghosh, S.K., E-mail: skghosh@metal.becs.ac.in [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Kundu, S.; Chatterjee, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2013-02-15

    A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching.

  10. Effect of various surface treatment methods on repair bond strength of composite restorations

    Directory of Open Access Journals (Sweden)

    Maryam Jafari

    2012-01-01

    Full Text Available AbstractIntroduction: In some cases repair of composite resin restorations is preferable to replacement. Various surface treatment methods have been introduced to improve the weak bond strength between the new and old composite resins. The aim of this study was to evaluate the effect of various surface treatment methods on repair bond strength of composite resin restorations.Materials and Methods: In this in vitro study, 56 composite resin specimens (Filtek Supreme were prepared and randomly divided into seven groups (one control group and six experimental groups. Then one of the surface treatment methods was used in the experimental groups as follows: group 1: diamond bur + phosphoric acid + bonding agent (Single Bond; group 2: diamond bur + phosphoric acid + silane + Single Bond; group 3: air abrasion (50-µm AL2O3 particles + phosphoric acid + Single Bond; group 4: air abrasion (50-µm AL2O3 particles + phosphoric acid + Silane + Single Bond; group 5: diamond bur + phosphoric acid + Clearfil Repair; group 6: diamond bur + phosphoric acid + Clearfil SE Bond. After bonding fresh composite resin, all the specimens were stored in distilled water at 37°C for 24h prior to measuring shear bond strength using a universal testing machine. Data were analyzed with one-way ANOVA and Tukey test (α=0.05.Results: The highest bond strength values were recorded in groups 2 and 5, with no significant differences (p value = 0.064; the lowest bond strength was recorded in group 1. Clearfil SB exhibited better results than Single Bond (p value = 0.039 and Clearfil Repair Bond exhibited better results than Clearfil SB Bond (p value = 0.038.Conclusion: Surface treatment with diamond bur was more effective than air abrasion. Use of silane was affective in increasing bond strength. Clearfil Repair Bond had the best effect on repair bond strength of composite resins.Key words: Air abrasion, Bonding agent, Composite resins, Dental, Silane.

  11. Strength dynamics of weighted evolving networks

    Institute of Scientific and Technical Information of China (English)

    Wu Jian-Jun; Gao Zi-You; Sun Hui-Jun

    2007-01-01

    In this paper, a simple model for the strength dynamics of weighted evolving networks is proposed to characterize the weighted networks. By considering the congestion effects, this approach can yield power law strength distribution appeared on the many real weighted networks, such as traffic networks, internet networks. Besides, the relationship between strength and degree is given. Numerical simulations indicate that the strength distribution is strongly related to the strength dynamics decline. The model also provides us with a better description of the real weighted networks.

  12. On strength of porous material

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1999-01-01

    irregularities only scattered MOE-MOR relations (clouds) can be established from which no really results can be read.For homogeneously produced porous materials, however, like modern ceramics and high performance concretes MOE-MOR relations can be presented which are reliable. The present paper contributes to......The question of non-destructive testing of porous materials has always been of interest for the engineering profession. A number of empirically based MOE-MOR relations between stiffness (Modulus Of Elasticity) and strength (Modulus OF Rupture) of materials have been established in order to control...... quality without damaging or destroying the material or the building component considered. The efficiency of MOE-MOR relations for this purpose depends very much on the homogeneity of porous material considered. For building materials like wood and concrete of normal or lower quality with a number of...

  13. On strength of porous material

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1999-01-01

    quality without damaging or destroying the material or the building component considered. The efficiency of MOE-MOR relations for this purpose depends very much on the homogeneity of porous material considered. For building materials like wood and concrete of normal or lower quality with a number of......The question of non-destructive testing of porous materials has always been of interest for the engineering profession. A number of empirically based MOE-MOR relations between stiffness (Modulus Of Elasticity) and strength (Modulus OF Rupture) of materials have been established in order to control...... irregularities only scattered MOE-MOR relations (clouds) can be established from which no really results can be read.For homogeneously produced porous materials, however, like modern ceramics and high performance concretes MOE-MOR relations can be presented which are reliable. The present paper contributes to...

  14. Laser air photonics: beyond the terahertz gap

    Directory of Open Access Journals (Sweden)

    Benjamin Clough

    2012-01-01

    Full Text Available Through the ionization process, the very air that we breath is capable of generating terahertz (THz electromagnetic field strengths greater than 1 MV/cm, useful bandwidths of over 100 THz, and highly directional emission patterns. Following the ionization of air, the emitted air-plasma fluorescence or acoustics can serve as an omnidirectional, broadband, THz wave sensor. Here we review significant advances in laser air photonics that help to close the “THz gap,” enabling ultra-broadband THz wave generation and detection, for applications including materials characterization and non-destructive evaluation. The feasibility for remote sensing, as well as the remaining challenges and future opportunities are also discussed.

  15. Air protection. Ochrana ovzdusia

    Energy Technology Data Exchange (ETDEWEB)

    Siska, F.

    1980-01-01

    This paper discusses problems of air pollution control, air pollution abatement and effects of air pollution. Air pollution caused by black and brown coal combustion, by fossil-fuel power plants and by coking plants is evaluated. Air pollution by dusts, sulfur oxides, nitrogen oxides, carbon monoxide, ammonia as well arsenic, barium, beryllium, boron, chromium, gallium, cobalt, manganese, copper, nickel, lead, plutonium, titanium and vanadium, which sometimes accompany ashes in coal, is analyzed. Methods of air pollution abatement such as fluidized bed combustion, coal preparation, desulfurization or dry coke quenching are described. Systems for air pollution control are presented: air filtration, cyclones, electrostatic precipitators. Systems of air pollution measurement and recording are evaluated. Propagation of air pollutants in the atmosphere as well as the factors which influence pollutant propagation are characterized. Problems associated with site selection for fossil-fuel power plants are also discussed. An analysis of economic aspects of air pollution abatement and air pollution control is made. (55 refs.)

  16. Indoor Air Quality

    Science.gov (United States)

    ... protect yourself and your family. Learn more Air Quality at Work Workers should breathe easy while on the job, but worksites with poor air quality put employees at risk. Healthy air is essential ...

  17. HEPA air filter (image)

    Science.gov (United States)

    ... pet dander and other irritating allergens from the air. Along with other methods to reduce allergens, such ... controlling the amount of allergens circulating in the air. HEPA filters can be found in most air ...

  18. Bad Air Day

    Science.gov (United States)

    ... link, please review our exit disclaimer . Subscribe Bad Air Day Air Quality and Your Health In many parts of the country, summer has the worst air quality of any season. When the forecast says ...

  19. Strength Distribution Analysis of Typical Staple Fibers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The strength of staple fiber is an important property for yarns and fabrics. Usually there are variations in individual fiber strength, and this will affect the final strength of yarns and fabrics. In this study, Weibull distribution function is used to analyze the strength distribution of various staplefibers. The strengths of wool, silk, cotton, flax, acrylic, polyester, glass, aramid and carbon fiber are tested. It isfound that the strengths of cotton, polyester, glass, aramid and carbon fiber fit well with the two-factor Weibulldistribution, while those of wool and silk with the threefactir Weibull distribution. However, the strength distributionof flax cannot be expressed by either two- or three-factor Weibull distribution convincingly.

  20. Evidential Reasoning in Air Battle Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Bayesian statistics assigns basic probabilities to singletons (single element sets). The Dempster-Shafer evidence theory generalizes Bayesian statistics by assigning basic probabilities to subsets to represent evidence and to develop evidential reasoning. This paper discusses what is the strength of evidence theory. As an application of evidence theory, evidential reasoning in air battle systems is discussed. In the air battle system, evidential reasoning is applied to fuse the multisensor information and identify the type of aircraft. The effectiveness of this fusion approach is evaluated by simulated data.

  1. Effect of polymer coatings on fatigue strength of aluminum alloy 2024 box beams

    Science.gov (United States)

    Nordmark, G. E.; Kelsey, R. A.

    1972-01-01

    Previous investigators have shown that polymer coatings raise the fatigue strength of metals tested in air to about the same level as that of uncoated specimens tested in vacuum. The results are given of tests to determine if a polymer coating would improve the fatigue strength of built-up aluminum alloy members simulating aircraft construction. Aluminum alloy 2024-T4 riveted box beams were subjected to constant amplitude fatigue tests in air as well as in salt water fog. The coating did not improve the fatigue strength of beams tested in either environment. This is believed to result from the fact that most failures originated at rivet holes, which were isolated from both the coating and the environment.

  2. An experimental study on the estimation of the strength of hardened concrete

    International Nuclear Information System (INIS)

    The need to asses the strength of hardened concrete in an existing structure can arise from a variety of reasons, especially such as doubt of non-destructive test methods. According the study aims at suggesting the practical basic material through sampling the concrete conveyed to the construction site by mixer truck shortly before its placing, employing the non-destructive test methods and the location surveying compressive strength test methods with regard to the compressive strength of the concrete after 28 days of age passed after the placing of concrete, securing the uniformity of concrete structure, and comparing and analyzing the difference between the non-destructive test methods and the location surveying compressive strength. The test was conducted in the following methods at the concrete placing work on the real site, as the test able among several factors which execute on effect on compressive strength in this study. Used concrete was the Remicon product of A company, and cured until 28 days of aging by water curing, drawing up the standard cylinder specimen on The construction site. The estimated formula of the compressive strength, in accordance with the results of the experiments conducted by the Schmidt Hammer test method and the ultrasonics pulse velocity test method, Air Exclusion Test method are as follows : (1) Schmidt Hammer Test Method Fc = 16.75R - 325.5 (2) Ultra Sonic Test Method Fc = 277.22VP - 846.78 (3) Concrete Air Exclusion Rating Table.

  3. Characteristics of structural loess strength and preliminary framework for joint strength formula

    Institute of Scientific and Technical Information of China (English)

    Rong-jian LI; Jun-ding LIU; Rui YAN; Wen ZHENG; Sheng-jun SHAO

    2014-01-01

    The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress ( Kf line), and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests:the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural loess comprehensively and reasonably, a joint strength formula for structural loess was established. This formula comprehensively considers tensile and shear properties. Studies have shown that the tensile strength exhibits a decreasing trend with increasing water content. When the water content is constant, the tensile strength of the structurally intact soil is greater than that of remolded soil. In the studies, no loss of the originally cured cohesion in the structurally intact soil samples was observed, given that the soil samples did not experience loading disturbance during the uniaxial compressive strength test, meaning there is a high initial structural strength. The results of the conventional triaxial shear strength test show that the water content is correlated with the strength of the structural loess. When the water content is low, the structural properties are strong, and when the water content is high, the structural properties are weak, which means that the water content and the ambient pressure have significant effects on the stress-strain relationship of structural loess. The established joint strength formula of structural loess effectively avoids overestimating the role of soil tensile strength in the traditional theory of Mohr-Coulomb strength.

  4. Research review: Indoor air quality control techniques

    International Nuclear Information System (INIS)

    Techniques for controlling the concentration of radon, formaldehyde, and combustion products in the indoor air are reviewed. The most effective techniques, which are generally based on limiting or reducing indoor pollutant source strengths, can decrease indoor pollutant concentrations by a factor of 3 to 10. Unless the initial ventilation rate is unusually low, it is difficult to reduce indoor pollutant concentrations more than approximately 50% by increasing the ventilation rate of an entire building. However, the efficiency of indoor pollutant control by ventilation can be enhanced through the use of local exhaust ventilation near concentrated sources of pollutants, by minimizing short circuiting of air from supply to exhaust when pollutant sources are dispersed and, in some situations, by promoting a displacement flow of air and pollutants toward the exhaust. Active air cleaning is also examined briefly. Filtration and electrostatic air cleaning for removal of particles from the indoor air are the most practical and effective currently available techniques of air cleaning. 49 refs., 7 figs

  5. Elastic stability and the limit of strength

    International Nuclear Information System (INIS)

    The upper limit of strength (the ''theoretical strength'') has been an active subject of research and speculation for the better part of a century. The subject has recently become important, for two reasons. First, given recent advances in ab initio techniques and computing machines, the limits of strength can be calculated with considerable accuracy, making this one of the very few problems in mechanical behavior that can actually be solved. Second, given recent advances in materials engineering, the limits of strength are being approached in some systems, such as hardened or defect-free films, and their relevance is becoming recognized in others. The present paper discusses some interesting results from recent research on the limits of strength, with an intermixture of speculations based on those results. Topics include the inherent nature of {100} cleavage and ''pencil slip'' in bcc metals, the inherent ductility of fcc metals, the anomalous properties of Al, and the possibility of measuring ideal strength with nanoindentation

  6. Strength and conditioning practices in rowing

    OpenAIRE

    Gee, Thomas

    2008-01-01

    There is minimal research on the practices of strength and conditioning coaches in England. Information about training programme design could be useful in developing models of good practice and ecologically valid intervention studies. The aim of the research was to quantify the training practices of coaches responsible for the strength and conditioning of rowing athletes. A questionnaire was developed and consisted of six sections: (a) personal details, (b) physical testing, (c) strength/powe...

  7. Dynamic strength of molecular adhesion bonds.

    OpenAIRE

    Evans, E; Ritchie, K

    1997-01-01

    In biology, molecular linkages at, within, and beneath cell interfaces arise mainly from weak noncovalent interactions. These bonds will fail under any level of pulling force if held for sufficient time. Thus, when tested with ultrasensitive force probes, we expect cohesive material strength and strength of adhesion at interfaces to be time- and loading rate-dependent properties. To examine what can be learned from measurements of bond strength, we have extended Kramers' theory for reaction k...

  8. REACH. Air Conditioning Units.

    Science.gov (United States)

    Garrison, Joe; And Others

    As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of air conditioning. The instructional units focus on air conditioning fundamentals, window air conditioning, system and installation, troubleshooting and…

  9. Strength of ship plates under combined loading

    DEFF Research Database (Denmark)

    Cui, Weiching; Wang, Yongjun; Pedersen, Preben Terndrup

    2000-01-01

    Strength of ship plates plays a significant role for the ultimate strength analysis of ship structures. In recent years several authors have proposed simplified methods to calculate the ultimate strength of unstiffened plates. The majority of these investigations deal with plates subjected to...... that the simplified method is able to determine the ultimate strength of unstiffened plates with imperfections in the form of welding induced residual stresses and geometric deflections subjected to combined loads. Comparisons with experimental results show that the procedure has sufficient accuracy...

  10. Factors affecting maximal momentary grip strength.

    Science.gov (United States)

    Martin, S; Neale, G; Elia, M

    1985-03-01

    Maximal voluntary grip strength has been measured in normal adults aged 18-70 years (17 f, 18 m) and compared with other indices of body muscle mass. Grip strength (dominant side) was directly proportional to creatinine excretion (r = 0.81); to forearm muscle area (r = 0.73); to upper arm muscle area (r = 0.71) and to lean body mass (r = 0.65). Grip strength relative to forearm muscle area decreased with age. The study of a subgroup of normal subjects revealed a small but significant postural and circadian effect on grip strength. The effect on maximal voluntary grip strength of sedatives in elderly subjects undergoing routine endoscopy (n = 6), and of acute infections in otherwise healthy individuals (n = 6), severe illness in patients requiring intensive care (n = 6), chronic renal failure (n = 7) and anorexia nervosa (n = 6) has been assessed. Intravenous diazepam and buscopan produced a 50 per cent reduction in grip strength which returned to normal within the next 2-3 h. Acute infections reduced grip strength by a mean of 35 per cent and severe illness in patients in intensive care by 60 per cent. In patients with chronic renal failure grip strength was 80-85 per cent of that predicted from forearm 'muscle area' (P less than 0.05). In anorectic patients the values were appropriate for their forearm muscle area. Nevertheless nutritional rehabilitation of one anorectic patient did not lead to a consistent improvement in grip strength. PMID:3926728

  11. High-Strength Glass Fibers and Markets

    Science.gov (United States)

    Hausrath, Robert L.; Longobardo, Anthony V.

    High-strength glass fibers play a crucial role in composite applications requiring combinations of strength, modulus, and high-temperature stability. Compositions in the high-strength glass group include S-glass and R-glass, which are used for applications requiring physical properties that cannot be satisfied by conventional E-glass. Additional compositions are also available for specialized applications requiring extreme performance in any one area. The main competition for high-strength glasses in the marketplace comes from carbon and polymer fibers. Ultimately, the product of choice is based on a compromise between cost and performance and will vary depending on the application.

  12. Accelerated Strength Testing of Thermoplastic Composites

    Science.gov (United States)

    Reeder, J. R.; Allen, D. H.; Bradley, W. L.

    1998-01-01

    Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.

  13. ANALYTICAL DETERMINATION OF RESIDUAL STRENGTH AND LINKUP STRENGTH FOR CURVED PANELS, WITH MULTIPLE SITE DAMAGE

    Directory of Open Access Journals (Sweden)

    Elangovan.R ,

    2011-05-01

    Full Text Available Airplane fuselage has a large number of riveted joints and is subjected to a major loading of differential internal pressure at cruise altitude and zero pressure on the ground. This constitutes one of the major load cycle on the fuselage often referred to as ground air ground (G-A-G cycle. Due to presence of large number of rivet holes, the fuselage skins have a large number of high stress locations and these are locations of potential crack initiation. Thus at the skin joints of the fuselage shell one can have a number of cracks as it ages (i.e used over a period of time. The practice in earlier time was to consider the largest sized crack and considerits acceptance or otherwise. But in fuselage panels one may have one dominate crack and number of smaller secondary cracks. The understanding the safety of a panel with multi site damages is of concern to airline operations. The present paper deals with the estimation of the strength of a flat panel with multi site damage andlead on to estimation of residual life, using fracture mechanics based approach.

  14. Recent Results on Singularity Strengths

    Science.gov (United States)

    Nolan, Brien

    2002-12-01

    In this contribution, we review some recent results on strengths of singularities. In a space-time (M,g), let γ[τ0, 0) → M be an incomplete, inextendible causal geodesic, affinely parametrised by τ, tangent ěc k. Let Jτ1 :=set of Jacobi fields along γ, orthogonal to γ and vanishing at time τ1 ≥ τ0 i.e. ěc ξ ∈ J{τ 1 } iff D2ξa = -Rbcdakbkdξc, gabξakb = 0, and ěc ξ (τ 1 ) = 0. Vτ1(τ) := volume element defined by full set of independent elements of Jτ1 (2-dim for null geodesies, 3-dim for time-like); Vτ1 := ∥Vτ1∥. Definition (Tipler 1977): γ terminates in a gravitationally strong singularity if for all 0 > τ1 ≥ τ0, lim infτ→0- Vτ1(τ) = 0. γ... gravitationally weak ... lim infτ→0- Vτ1(τ) > 0. The interpretation is that at a strong singularity, an extended body, e.g. a gravitational wave detector, is crushed to zero volume by the singularity. Tipler's definition does not take account of the possibility that (i) V → ∞ or (ii) V → finite, non-zero value, but with infinite stretching/crushing in orthogonal directions ('spaghettifying singularity'). Extended definition (Nolan 1999): strong if either V → 0,∞ or if for every τ1, there is an element ěc ξ of Jτ1 satisfying ||ěc ξ || -> 0. Otherwise weak. (Ori 2000): singularity is 'deformationally strong' if either (i) it is Tipler-strong or (ii) for every τ1, there is an element ěc ξ of Jτ1 satisfying ||ěc ξ || -> ∞ . Otherwise, deformationally weak...

  15. Impact of air entrainment on the microstructure and mechanical performance of high performance mortar

    OpenAIRE

    Dils, Jeroen; Boel, Veerle; De Schutter, Geert

    2015-01-01

    At the Magnel Laboratory for Concrete Research an intensive vacuum mixer which can regulate the air pressure is available. As such the amount of entrapped air in cementitious materials can be varied. The effect of the reduced air content due to vacuum mixing on the rheology and workability was already investigated in previous work. Furthermore, the previous work investigated the influence of entrained air on the rheological properties. The impact of vacuum mixing on the compressive strength a...

  16. Beyond KERMA - neutron data for biomedical applications

    International Nuclear Information System (INIS)

    Presently, many new applications of fast neutrons are emerging or under development, like dose effects due to cosmic-ray neutrons for airplane crew, fast-neutron cancer therapy, studies of electronic failures induced by cosmic-ray neutrons, and accelerator-driven incineration of nuclear waste and energy production technologies. All these areas would benefit from improved neutron dosimetry. In this paper, the present rapid progress on measurements of double-differential neutron-induced nuclear reaction data are described. With such data at hand, the full response of, in principle, any system, including human tissue, can be calculated in detail. This could potentially revolutionise our understanding of biological effects in tissue due to fast neutrons. (author)

  17. Indoor Air Pollution (Environmental Health Student Portal)

    Science.gov (United States)

    ... Students to Environmental Health Information Menu Home Air Pollution Air Pollution Home Indoor Air Pollution Outdoor Air Pollution ... Pollution Indoor Air Pollution Print this Page Air Pollution Air Pollution Home Indoor Air Pollution Outdoor Air Pollution ...

  18. Microstructure, strength, and oxidation of a 10 wt pct zyttrite-Si3N4 ceramic

    Science.gov (United States)

    Dutta, S.; Buzek, B.

    1984-01-01

    Hot pressed Si3N4 doped with 10 wt pct zyttrite as a sintering aid was studied. An equiaxed, fine grained microstructure was predominant, with no apparent porosity. Bend strengths were determined at room temperature and high temperatures (up to 1370 C). Oxidation was measured by weight gain at 1370 C in air. The resulting material exhibited very good room temperature strength (755 MPa). The work showed that room temperature strength can be improved significantly by using controlled Si3N4 powder with 10 wt pct zyttrite. High temperature strength (514 MPa) at 1370 C was nearly double that of hot-pressed Si3N4 (NC-132). The oxidation resistance at 1370 C was also higher than that of NC-132.

  19. Solar cell contact pull strength as a function of pull-test temperature

    Science.gov (United States)

    Yasui, R. K.; Berman, P. A.

    1972-01-01

    Four types of solar cell contacts were given pull-strength tests at temperatures between -173 and +165 C. Contacts tested were: (1) solder-coated titanium-silver contacts on n-p cells, (2) palladium-containing titanium-silver contacts on n-p cells, (3) titanium-silver contacts on 0.2-mm-thick n-p cells, and (4) solder-coated electroless-nickel-plated contacts on p-n cells. Maximum pull strength was demonstrated at temperatures significantly below the air mass zero cell equilibrium temperature of +60 C. At the lowest temperatures, the chief failure mechanism was silicon fracture along crystallographic planes; at the highest temperatures, it was loss of solder strength. In the intermediate temperatures, many failure mechanisms operated. Pull-strength tests give a good indication of the suitability of solar cell contact systems for space use. Procedures used to maximize the validity of the results are described.

  20. Effect of Various Surface Treatment on Repair Strength of Composite Resin

    Directory of Open Access Journals (Sweden)

    Y. Alizade

    2004-12-01

    Full Text Available Statement of Problem: In some clinical situations, repair of composite restorations is treatment of choice. Improving the bond strength between one new and old composite usually requires increased surface roughness to promote mechanical interlocking sincechemical bonding might not be adequate. Similarly, the treatment of a laboratory fabricated resin composite restoration involves the same procedures, and there is a need to create the strongest possible bond of a resin cement to a previously polymerized composite.Purpose: The aim of this study was to evaluate the effect of various surface treatments on the shear bond strength of repaired to aged composite resin.Materials and Methods: Eighty four cylindrical specimens of a composite resin were fabricated and stored in distilled water for 100 days prior to surface treatment. Surface treatment of old composite was done in 6 groups as follow:1- Air abrasion with CoJet sand particles with micoretcher + silane + dentin bonding agent2- Air abrasion with 50μm Al2O3 particles+ phosphoric acid+ silane+ dentin bonding agent3- Air abrasion with 50μm Al2O3 particles + phosphoric acid + dentin bonding agent4- Diamond bur + phosphoric acid + silane + dentin bonding agent5- Diamond bur + phosphoric acid + dentin bonding agent6- Diamond bur + phosphoric acid + composite activator + dentin bonding agentThen fresh composite resin was bonded to treated surfaces. Twelve specimens were also fabricated as control group with the same diameter but with the height twice as much as other specimens. All of the specimens were thermocycled prior to testing for shear bondstrength. The bond strength data were analyzed statistically using one way ANOVA test, t test and Duncan's grouping test.Results: One-way ANOVA indicated no significant difference between 7 groups (P=0.059. One-way ANOVA indicated significant difference between the three diamond bur groups (P=0.036. Silane had a significant effect on the repair bond

  1. Effect of coconut fibre ash on strength properties of concrete

    Directory of Open Access Journals (Sweden)

    Rajeev Chandak

    2015-04-01

    Full Text Available Concrete is the construction material which is obtained by mixing of cement, water and aggregate in required proportions. The day by day the cost of cement is increasing, yet the need for building and other construction requiring this material keep growing with an increase in the population, thus the need to find alternative binding materials that can be used solely or in partial replacement of cement. Agricultural waste material, In this case coconut fibre ash, which is an environmental pollutant. Coconut fibres are collected and the fibre are properly dried and burnt in the open air with a temperature range of 6000 c to 7000 c. when the fibres turned into ash. The ash was collected and made to pass through 150 micron sieve. This work presents the results of laboratory test carried out using coconut fibre ash (CFA as a partial replacement for cement in concrete production. Concrete cubes are cast and tested at curing aging of 7, 28, 60, & 90 days using 0, 5, 10, 15, 20, & 25 percent replacement levels. The slump test results show that the workability of the concrete decreased as the CFA content increased & the compressive strength of CFA concrete increased with curing aging but decrease with increasing the percentage of coconut fibre ash. The percentage strength gained at 90 days for 5% and 10% for the control of 0% is 96.22% & 86.12% respectively. The optimum compressive strength of 59.25N/mm2 was obtained at 5% replacement at 90 days of ages. The percentage strength at this optimum point of the control is 96.22%.

  2. Impact of Hydrodynamics on Oral Biofilm Strength

    NARCIS (Netherlands)

    Paramonova, E.; Kalmykowa, O. J.; van der Mei, H. C.; Busscher, H. J.; Sharma, P. K.

    2009-01-01

    Mechanical removal of oral biofilms is ubiquitously accepted as the best way to prevent caries and periodontal diseases. Removal effectiveness strongly depends on biofilm strength. To investigate the influence of hydrodynamics on oral biofilm strength, we grew single- and multi-species biofilms of S

  3. The Strengths Revolution: A Positive Psychology Perspective

    Science.gov (United States)

    Peterson, Christopher

    2013-01-01

    Christopher Peterson received the Circle of Courage Award and made the following address in a symposium on "The Strength-Based Revolution" at Wayne State University in Detroit, Michigan (Peterson & Brendtro, 2008). Dr. Peterson shared personal reflections on the strengths movement, which is transforming youth development. His presentation shows…

  4. Experimental and simulated strength of spot welds

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Bennedbæk, Rune A.K.; Larsen, Morten B.;

    2014-01-01

    Weld strength testing of single spots in DP600 steel is presented for the three typical testing procedures, i.e. tensile-shear, cross-tension and peel testing. Spot welds are performed at two sets of welding parameters and strength testing under these conditions is presented by load-elongation cu...

  5. Determining the bulk strength of strata

    International Nuclear Information System (INIS)

    The bulk rock strength of strata is determined by logging a bore-hole with an instrument to obtain a neutron-neutron log of the hole and determining in conjunction with the lithology of the strata the strength by applying an inverse relation formula. (author)

  6. Elastic buckling strength of corroded steel plates

    Indian Academy of Sciences (India)

    Ahmad Rahbar-Ranji

    2013-02-01

    Corrosion makes structures more vulnerable to buckling and yielding failures. It is common practice to assume a uniform thickness reduction for general corrosion. To estimate the remaining strength of corroded structures, typically a much higher level of accuracy is required, since the actual corroded structures have irregular surfaces. Elastic buckling of simply supported rectangular corroded plates are studied with one- and both-sided irregular surfaces. Eigenvalue analysis by using finite element method (FEM) is employed for computing Euler stress. The influence of various geometric and corrosion characteristics are investigated and it is found that the aspect ratio of the plate, the average thickness diminution, the standard deviation of thickness diminution and the amount of corrosion loss have influence on the reduction of buckling strength of the corroded plates. Buckling strength of one- and both-sided corroded plates are the same. In plates with low value of aspect ratio, reduction of buckling strength is negligible. Reduction of buckling strength is more prominent in plates with higher aspect ratio. Reduction of buckling strength is very sensitive to the amount of corrosion loss; the higher the amount of corrosion loss, the more reduction of buckling strength. Reduction of buckling strength is less sensitive to the standard deviation of thickness diminution.

  7. Stepfamily Strengths: A Review of Popular Literature.

    Science.gov (United States)

    Coleman, Marilyn; And Others

    1985-01-01

    Reviewed popular literature (self-help books, magazines, adolescent fiction) that identified stepfamily strengths. Potential strengths of stepfamily life were identified in all three sources. The primary focus of self-help literature and magazine articles, however, was on stepfamily problems. Concludes that adolescent fiction may be used to good…

  8. Oxide driven strength evolution of silicon surfaces

    International Nuclear Information System (INIS)

    Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation

  9. 46 CFR 177.1020 - Strength.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Strength. 177.1020 Section 177.1020 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Window Construction and Visibility § 177.1020 Strength. Each window, port hole, and its means...

  10. Static Material Strength Determined Using a DAC

    Energy Technology Data Exchange (ETDEWEB)

    Cynn, H; Evans, W; Klepeis, J P; Lipp, M; Liermann, P; Yang, W

    2009-06-04

    By measuring sample thickness and pressure gradient using x-ray absorption and x-ray diffraction, respectively, the accurate static yield strengths of Ta and Fe were determined at high pressure. This improved method has several advantages over other similar methods to quantitatively determine static material strength.

  11. MECHANICAL STRENGTH OF HIGHLY POROUS CERAMICS

    NARCIS (Netherlands)

    VANDENBORN, IC; SANTEN, A; HOEKSTRA, HD; DEHOSSON, JTM; Born, I.C. van den

    1991-01-01

    This paper reports on the mechanical strength of highly porous ceramics in terms of the Weibull and Duxbury-Leath distributions. More than 1000 side-crushing strength tests on silica-catalyst carriers of various particle sizes have been performed in series. Within a series, preparation conditions we

  12. Oxide driven strength evolution of silicon surfaces

    Science.gov (United States)

    Grutzik, Scott J.; Milosevic, Erik; Boyce, Brad L.; Zehnder, Alan T.

    2015-11-01

    Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.

  13. Oxide driven strength evolution of silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Grutzik, Scott J.; Zehnder, Alan T., E-mail: atz2@cornell.edu [Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States); Milosevic, Erik [Department of Nanoengineering, SUNY Polytechnic University, Albany, New York 12203 (United States); Boyce, Brad L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0889 (United States)

    2015-11-21

    Previous experiments have shown a link between oxidation and strength changes in single crystal silicon nanostructures but provided no clues as to the mechanisms leading to this relationship. Using atomic force microscope-based fracture strength experiments, molecular dynamics modeling, and measurement of oxide development with angle resolved x-ray spectroscopy we study the evolution of strength of silicon (111) surfaces as they oxidize and with fully developed oxide layers. We find that strength drops with partial oxidation but recovers when a fully developed oxide is formed and that surfaces intentionally oxidized from the start maintain their high initial strengths. MD simulations show that strength decreases with the height of atomic layer steps on the surface. These results are corroborated by a completely separate line of testing using micro-scale, polysilicon devices, and the slack chain method in which strength recovers over a long period of exposure to the atmosphere. Combining our results with insights from prior experiments we conclude that previously described strength decrease is a result of oxidation induced roughening of an initially flat silicon (1 1 1) surface and that this effect is transient, a result consistent with the observation that surfaces flatten upon full oxidation.

  14. Derived strengths of preference relations on coordinates

    OpenAIRE

    Wakker, Peter

    1988-01-01

    textabstractway is indicated to derive, from a preference relation on a Cartesian product, strength of preference relations on the coordinate sets. These strengths of preference relations are then used to reformulate several well-known properties of preference relations, and make their meaning more transparent. A new result for dynamic contexts is given.

  15. Lifetime and residual strength of materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1997-01-01

    of load amplitude, load average, fractional time under maximum load, and load frequency.The analysis includes prediction of residual strength (re-cycle strength) during the process of load cycling. It is concluded that number of cycles to failure is a very poor design criterion. It is demonstrated...

  16. Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Ju CHEN; Wei-liang JIN

    2008-01-01

    In this study,the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at norrnal room temperature was investigated.The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen.Based on the experimental results,an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed.The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures.It is shown that the predictions obtained from the proposed model agree well with the test results.Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

  17. Sensory source strength of used ventilation filters

    DEFF Research Database (Denmark)

    Clausen, Geo; Alm, Ole Martin; Fanger, Povl Ole

    2002-01-01

    the experimental space after facial exposure, without entering the space. Alternatively, the panel could enter the space and evaluate the air quality after full exposure to the air. The sensory pollution load of the filter determined from full exposure was approximately 7 times lower than when......A two-year-old filter was placed in a ventilation system recirculating the air in an experimental space. Via glass tubes supplied with a small fan it was possible to extract air upstream and downstream of the filter to an adjacent room. A panel could thus perform sensory assessments of the air from...... determined after facial exposure. Even with the lower values of the sensory pollution load found in the present study, model predictions of the perceived air quality in a typical office show that used filters may still be important sources of indoor air pollution....

  18. Shear Bond Strength of Composite-Resin to Porcelain: Effect of Thermocycling

    Directory of Open Access Journals (Sweden)

    M. Khoroushi

    2007-03-01

    Full Text Available Objective: Different ceramic repair systems have been reported for fractured ceramics.However, limited information is available concerning the bond strength of these systems especially after thermocycling. The aim of this in-vitro study was to determinethe effect of thermocycling on the shear bond strength of composite-resin to feldspathic porcelain with and without silane pretreatment.Materials and Methods: In this experimental study, forty porcelain blocks were prepared and randomly divided into four groups (n=10. All porcelain surfaces were etched with 9.6% hydrofluoric acid, rinsed and air dried. In groups 1 and 3, silane pretreatment was applied using Adper Scotchbond Multipurpose Plus (ASMP.Smallparticlecomposite-resin was subsequently added on the ceramic surfaces, and lightcured.Specimens of groups 3 and 4 then subjected to 1000 thermal cycles. Shear bond strength was determined on a universal testing machine at a crosshead speed of 1mm/min. Two-way ANOVA test (α=0.05 was used to analyze the bond strength.Results: There were statistically significant differences between study groups (P<0.05.Thermocycling caused a decrease in the shear bond strength for both silanized and nonsilanized groups.Conclusion: According to the results of this study, shear bond strength after thermocycling reduced considerably in ASMP system. In addition, silane treatment of porcelain was critical for achieving durable bond strength between composite-resin and porcelain.

  19. Impact of hydrodynamics on oral biofilm strength.

    Science.gov (United States)

    Paramonova, E; Kalmykowa, O J; van der Mei, H C; Busscher, H J; Sharma, P K

    2009-10-01

    Mechanical removal of oral biofilms is ubiquitously accepted as the best way to prevent caries and periodontal diseases. Removal effectiveness strongly depends on biofilm strength. To investigate the influence of hydrodynamics on oral biofilm strength, we grew single- and multi-species biofilms of Streptococcus oralis J22, Actinomyces naeslundii TV14-J1, and full dental plaque at shear rates ranging from 0.1 to 50 1/sec and measured their compressive strength. Subsequently, biofilm architecture was evaluated by confocal laser scanning microscopy. Multi-species biofilms were stronger than single-species biofilms, with strength values ranging from 6 to 51 Pa and from 5 to 17 Pa, respectively. In response to increased hydrodynamic shear, biofilm strength decreased, and architecture changed from uniform carpet-like to more "fluffy" with higher thickness. S. oralis biofilms grown under variable shear of 7 and 50 1/sec possessed properties intermediate of those measured at the respective single shears. PMID:19783800

  20. Strength optimized designs of thermoelastic structures

    DEFF Research Database (Denmark)

    Pedersen, Pauli; Pedersen, Niels Leergaard

    2010-01-01

    For thermoelastic structures the same optimal design does not simultaneously lead to minimum compliance and maximum strength. Compliance may be a questionable objective and focus for the present paper is on the important aspect of strength, quantified as minimization of the maximum von Mises stress...... alternative to mathematical programming, which with a large number of both design variables and strength constraints, is found non-practical, we choose simple recursive iterations to obtain uniform energy density and find by examples that the obtained designs are close to fulfilling also strength maximization....... In compliance minimization it may be advantageous to decrease the total volume, but for strength maximization it is argued that it is advantageous to keep the total permissible volume. With the thermoelastic analysis presented directly in a finite element formulation, simple explicit formulas for...

  1. High-strength, low-alloy steels.

    Science.gov (United States)

    Rashid, M S

    1980-05-23

    High-strength, low-alloy (HSLA) steels have nearly the same composition as plain carbon steels. However, they are up to twice as strong and their greater load-bearing capacity allows engineering use in lighter sections. Their high strength is derived from a combination of grain refinement; precipitation strengthening due to minor additions of vanadium, niobium, or titanium; and modifications of manufacturing processes, such as controlled rolling and controlled cooling of otherwise essentially plain carbon steel. HSLA steels are less formable than lower strength steels, but dualphase steels, which evolved from HSLA steels, have ferrite-martensite microstructures and better formability than HSLA steels of similar strength. This improved formability has substantially increased the utilization potential of high-strength steels in the manufacture of complex components. This article reviews the development of HSLA and dual-phase steels and discusses the effects of variations in microstructure and chemistry on their mechanical properties. PMID:17772810

  2. Experimental knee joint pain during strength training and muscle strength gain in healthy subjects

    DEFF Research Database (Denmark)

    Sørensen, T J; Langberg, Henning; Hodges, P W;

    2012-01-01

    Knee joint pain and reduced quadriceps strength are cardinal symptoms in many knee pathologies. In people with painful knee pathologies, quadriceps exercise reduces pain, improves physical function, and increases muscle strength. A general assumption is that pain compromises muscle function and...... thus may prevent effective rehabilitation. This study evaluated the effects of experimental knee joint pain during quadriceps strength training on muscle strength gain in healthy individuals....

  3. Mechanical strength of stems in aquatic macrophytes

    Directory of Open Access Journals (Sweden)

    Katarzyna Bociąg

    2011-04-01

    Full Text Available In populations of submerged macrophytes, individuals are selected in terms of resistance to the effect of hydrodynamic forces. The aim of this study was to check whether individuals growing in river water are more tensile and bending resistant than plants occurring in places not exposed to flow stress. We determined the ultimate tensile strength of stems in four macrophyte species, Potamogeton natans, P. pectinatus, Batrachium fluitans and Chara fragilis, which occur in two environmental variants: in running (current velocity of 0.1-0.6 m/s-1 and stagnant water. In addition, flexure of P. natans stems from both environmental variants was examined. What is more, the type and arrangement of strengthening structures in stems of the plants under study were determined. Potamogeton natans stems are the most resistant to stretching (15.6±4.7 N, while stems of P. pectinatus (3.3±1.0 N and Batrachium fluitans (2.6±0.8 N are less resistant. Chara fragilis (0.6±0.3 N has the least resistant stems. Batrachium, Chara and P. pectinatus are more resistant to stretching if they occur in a river current, whereas P. natans, in stagnant lake water. Ultimate bending moment of P. natans stems from lakes is also much greater than of stems from a river (9.75•10-3 – 4.25•10-3 Nm as compared to 2.12•10-3 – 1.00•10-3 Nm. The resistance of stems to breaking is directly proportional to the stem and thallus cross sectional areas. On the one hand, in all the studied Cormophyta species, the more resistant stems (in P. natans from stagnant water, in the others from running water are thicker and characterised by a higher contribution of air spaces in the overall stem cross-section. On the other hand, the stems retain their species specific structure and have a similar proportion of strengthening elements.

  4. 78 FR 59343 - Meeting of the National Commission on the Structure of the Air Force

    Science.gov (United States)

    2013-09-26

    ... Guard leadership who have been asked to testify and address the evaluation factors under consideration... components of the Air Force, taking advantage of the unique strengths and capabilities of each; (c)...

  5. Indoor Air Quality

    OpenAIRE

    Korlakunta Divya #1, M.Anil Kumar

    2013-01-01

    The main aim of our project is to maintain the indoor air quality.The analysis is done on different parameters like temperature,relativehumidity,CO2,lights,sens ors and air conditioners to maintain the indoor environment.This report provides overview on importance of indoor air quality in an office or any other closed structure. It also discusses about the effects of poor indoor air quality, the various factors that affect the indoor air quality and various methods to assess indoor air qualit...

  6. Improvement in Tensile Strength of Bamboo Knitted Fabric by Sol-Gel Coating

    Directory of Open Access Journals (Sweden)

    Awais Khatri

    2013-07-01

    Full Text Available Textiles made of bamboo regenerated fibre are reported to have lower tensile strength than the other cellulosic fibres, due to high porosity of the fibre. This paper was aimed to modify the bamboo knitted fabric by the sol-gel coating to improve the tensile strength with minimum effect on its inherent morphology and ultimate relevant properties such as good absorbency and air permeability. The paddry- bake process was employed for the coating where tetraethyl-orthosilicate and nano-titanium-dioxide were used as the active ingredients. The treated fabrics were tested for the tensile behaviour in terms of breaking strength and elongation and the sol-gel process recipe and parameters were optimised. The absorbency, air-permeability and washing durability of the coating were also tested for the optimised process. Results showed the increase in tensile strength of the fabric by sol-gel coating, whereas absorbency and air-permeability were almost unaffected. The coating results were unaffected even after a washing treatment (equivalent to 5 industrial washings. Additionally, the wrinkle recovery angle of the coated fabric was also tested and found improved.

  7. Microtensile bond strength and micromorphologic analysis of surface-treated resin nanoceramics

    Science.gov (United States)

    Park, Joon-Ho

    2016-01-01

    PURPOSE The aim of this study was to evaluate the influence of different surface treatment methods on the microtensile bond strength of resin cement to resin nanoceramic (RNC). MATERIALS AND METHODS RNC onlays (Lava Ultimate) (n=30) were treated using air abrasion with and without a universal adhesive, or HF etching followed by a universal adhesive with and without a silane coupling agent, or tribological silica coating with and without a universal adhesive, and divided into 6 groups. Onlays were luted with resin cement to dentin surfaces. A microtensile bond strength test was performed and evaluated by one-way ANOVA and Tukey HSD test (α=.05). A nanoscratch test, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy were used for micromorphologic analysis (α=.05). The roughness and elemental proportion were evaluated by Kruskal–Wallis test and Mann–Whitney U test. RESULTS Tribological silica coating showed the highest roughness, followed by air abrasion and HF etching. After HF etching, the RNC surface presented a decrease in oxygen, silicon, and zirconium ratio with increasing carbon ratio. Air abrasion with universal adhesive showed the highest bond strength followed by tribological silica coating with universal adhesive. HF etching with universal adhesive showed the lowest bond strength. CONCLUSION An improved understanding of the effect of surface treatment of RNC could enhance the durability of resin bonding when used for indirect restorations. When using RNC for restoration, effective and systemic surface roughening methods and an appropriate adhesive are required.

  8. Improvement in Tensile Strength of Bamboo Knitted Fabric by Sol-Gel Coating

    International Nuclear Information System (INIS)

    Textiles made of bamboo regenerated fibre are reported to have lower tensile strength than the other cellulosic fibres, due to high porosity of the fibre. This paper was aimed to modify the bamboo knitted fabric by the sol-gel coating to improve the tensile strength with minimum effect on its inherent morphology and ultimate relevant properties such as good absorbency and air permeability. The pad-dry-bake process was employed for the coating where tetraethyl-orthosilicate and nano-titanium-dioxide were used as the active ingredients. The treated fabrics were tested for the tensile behaviour in terms of breaking strength and elongation and the sol-gel process recipe and parameters were optimised. The absorbency, air-permeability and washing durability of the coating were also tested for the optimised process. Results showed the increase in tensile strength of the fabric by sol-gel coating, whereas absorbency and air-permeability were almost unaffected. The coating results were unaffected even after a washing treatment (equivalent to 5 industrial washings). Additionally, the wrinkle recovery angle of the coated fabric was also tested and found improved. (author)

  9. Evaluation of different mechanical surface treatments in tensile strength of direct composite resin repairs

    Directory of Open Access Journals (Sweden)

    Daniela MINATTI

    2005-05-01

    Full Text Available The aim of this study was to compare the effect of different mechanical surface treatments in the tensile strength of direct composite resin repairs.12 specimens were obtained in halter form, for the control group, and 24 in hemi-halter form for the other experimental groups. The specimens were stored for 30 days in artificial saliva before being repaired. The experimental groups were repaired after the mechanical surface treatment,through the mechanical retentions in the repairing surface, and also afterthe surface roughening with an air abrasion system. After mechanicaltreatment, the surface was etched with phosphoric acid and the adhesive system was used without a previous photo polymerizing to the repair material addition. After the tensile strength test it was observed that the group treated by macro-mechanical retentions presented significantly inferior strength values compared to the control group. Moreover, there were not observed significant differences among repaired groups,regardless mechanical surface treatment. Based on the results it was possible to conclude that air abrasion provided strength values in composite resin repairs similar to cohesive strength.

  10. Investigation of sport rock climbers’ handgrip strength

    Directory of Open Access Journals (Sweden)

    Burak Gürer

    2015-10-01

    Full Text Available This study aims to investigate handgrip strengths of elite sportsmen who are involved in sport rock climbing. Study group was composed of 144 sportsmen from 22 countries who participated in Petzl Roc Trip sport rock climbing festival held in Turkey between 14 and 19 October 2014. Data were collected by using Takei Grip-D brand hand dynamometer. The data collected were analyzed and interpreted by statistical package programme (SPSS 16.0. Results show meaningful differences between sportsmen’s right handgrip strength and left handgrip strength. Sportsmen’s right handgrip strength was found to be higher. Results differed based on gender as well. Left and right handgrip strength of males was found to be higher to those of females. No significant relationships were detected based on nationality, age, history of climbing and period of experience in climbing. Relationships were observed between Turkish male and female climbers’ right and left handgrip strengths. As a result, it can be claimed that right hand is used more often in sport rock climbing compared to the left hand. It is also believed that fingers and technique are crucial in sport rock climbing. Practices to develop finger strength and techniques are suggested.

  11. Air Quality Facilities

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Facilities with operating permits for Title V of the Federal Clean Air Act, as well as facilities required to submit an air emissions inventory, and other...

  12. Indoor Air Pollution

    Science.gov (United States)

    We usually think of air pollution as being outdoors, but the air in your house or office could also be polluted. Sources of indoor pollution include Mold and pollen Tobacco smoke Household products ...

  13. Allegheny County Air Quality

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — Air quality data from Allegheny County Health Department monitors throughout the county. Air quality monitored data must be verified by qualified individuals...

  14. Nuclear air cleaning

    International Nuclear Information System (INIS)

    This report briefly describes the history of the use of high- efficiency particulate air filters for air cleaning at nuclear installations in the United States and discusses future uses of such filters

  15. Air Quality System (AQS)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Air Quality System (AQS) database contains measurements of air pollutant concentrations from throughout the United States and its territories. The measurements...

  16. An assessment of burst strength distribution data for monitoring quality of condom stocks in developing countries.

    Science.gov (United States)

    Free, M J; Hutchings, J; Lubis, F; Natakusumah, R

    1986-03-01

    Laboratory tests were conducted on condoms to examine the changes that occur over time in indicators of condom burst strength, and to determine the relationship between laboratory-assessed condom burst strength and breakage during use in a developing country setting. Three groups of unaged condoms purchased directly from the manufacturer were used: one group exposed to UV light for 10 hours; one group exposed for five hours; and one group unexposed. A sample of each of these groups was tested according to ISO condom air burst test protocols. The remaining condoms were individually packaged in coded polyethylene bags for shipment to the developing country study site. Also used in the study was a group of condoms that had been aged for over 40 months under field conditions in a tropical climate; a sample from this group was tested by the ISO air burst test protocol and the remainder distributed to the study site. One-hundred-thirty Indonesian urban males participated in the double-blind study. Volunteers were not relying on the condom for contraceptive purposes. Each volunteer was given one individually packaged untreated condom, one condom from each treatment group, and four condoms aged in the field. Study participants were instructed to return all used condoms. Each condom that was returned after use was examined for breakage, and the unbroken condoms were subjected to an air inflation test to determine volume and pressure at burst. A comparison of the air burst volume data for a sample of unused and used condoms from the same treatment group indicates that most of the condoms that broke during use had air burst volumes below 11 liters. Therefore, a significant downward shift in the burst strength distribution as measured in the laboratory is likely to result in an increased breakage rate during use. A Condom Deterioration Index calculated from regular periodic testing of stored condom stocks is a convenient and sensitive means of monitoring trends in the

  17. Effect of different surface treatments on shear bond strength of zirconia to three resin cements

    Science.gov (United States)

    Dadjoo, Nisa

    Statement of problem: There are no standard guidelines for material selection to obtain acceptable bonding to high-strength zirconium oxide ceramic. Studies suggest resin cements in combination with MDP-containing primer is a reasonable choice, however, the other cements cannot be rejected and need further investigation. Objective: The purpose of this in vitro study was the evaluation of the shear bond strength of three composite resin cements to zirconia ceramic after using different surface conditioning methods. Materials and methods: One hundred and twenty sintered Y-TZP ceramic (IPS e.max ZirCAD) squares (8 x 8 x 4 mm) were embedded in acrylic molds, then divided into three groups (n=40) based on the type of cement used. Within each group, the specimens were divided into four subgroups (n=10) and treated as follows: (1) Air abrasion with 50microm aluminum oxide (Al2O 3) particles (ALO); (2) Air abrasion + Scotchbond Universal adhesive (SBU); (3) Air abrasion + Monobond Plus (MBP); (4) Air abrasion + Z-Prime Plus (ZPP). Composite cylinders were used as carriers to bond to conditioned ceramic using (1) RelyX Ultimate adhesive resin cement (RX); (2) Panavia SA self-adhesive resin cement (PSA); (3) Calibra esthetic cement (CAL). The bonded specimens were submerged in distilled water and subjected to 24-hour incubation period at 37°C. All specimens were stressed in shear at a constant crosshead speed of 0.5 mm/min until failure. Statistical analysis was performed by ANOVA. The bond strength values (MPa), means and standard deviations were calculated and data were analyzed using analysis of variance with Fisher's PLSD multiple comparison test at the 0.05 level of significance. The nature of failure was recorded. Results: The two-way ANOVA showed Panavia SA to have the highest strength at 44.3 +/- 16.9 MPa (presin cement, Panavia SA, yielded the strongest bond to Y-TZP ceramic when compared to adhesive (RelyX Ultimate) or esthetic (Calibra) resin cements. Air

  18. Indoor air: Reference bibliography

    International Nuclear Information System (INIS)

    The U. S. Environmental Protection Agency initially established the indoor air Reference Bibliography in 1987 as an appendix to the Indoor Air Quality Implementation Plan. The document was submitted to Congress as required under Title IV--Radon Gas and Indoor Air Quality Research of the Superfund Amendments and Reauthorization Act of 1986. The Reference Bibliography is an extensive bibliography of reference materials on indoor air pollution. The Bibliography contains over 4500 citations and continues to increase as new articles appear

  19. The Influence of Applied Stress Ratio on Fatigue Strength of TiN-coated Carbon Steel

    OpenAIRE

    Shiozawa, Kazuaki; Nishino, Seiichi; Handa, Keiichi

    1992-01-01

    The influence of applied stress ratio on the fatigue strength of carbon steel coated with TiN was studied on the basis of measurement of crack initiation with the D. C. potential method. Fatigue tests were performed under the stress ratios of R=0 and -1 in air using the round notched specimens of O.37%C steel, JIS S35C, normalized and coated with TiN by physical vapor deposition (PVD) and chemical vapor deposition (CVD). From the experimental results, increase in fatigue strength was observed...

  20. Experimental knee pain reduces muscle strength

    DEFF Research Database (Denmark)

    Henriksen, Marius; Mortensen, Sara Rosager; Aaboe, Jens;

    2011-01-01

    experimental knee pain in healthy volunteers, and if these changes were associated with the pain intensities. In a crossover study, 18 healthy subjects were tested on 2 different days. Using an isokinetic dynamometer, maximal muscle strength in knee extension and flexion was measured at angular velocities 0....... Knee pain reduced the muscle strength by 5 to 15% compared to the control conditions (P <.001) in both knee extension and flexion at all angular velocities. The reduction in muscle strength was positively correlated to the pain intensity. Experimental knee pain significantly reduced knee extension and...

  1. Transient heating effect on high strength concrete

    International Nuclear Information System (INIS)

    This study shows some differences in the properties and the behaviour at high temperature of two concretes (ordinary and high strength) made with the same calcareous aggregates. During heating tests at 1 C min-1, cylindrical samples of diameter 160 x 320 mm of high strength concrete, more dense, may explode in a critical temperature zone between 250 and 300 C. Differences in behaviour between OC and HSC appeared at high temperatures: there were disparities especially in thermo-hydric transfer, porosity and thermal stability. The dense microstructure of high strength concrete was found to slow up the escape of vaporized water. (orig.)

  2. Transitional gamma strength in Cd isotopes

    OpenAIRE

    Larsen, André; Ruud, I. E.; Burger, Arnold; Goriely, Stéphane; Guttormsen, Magne; Görgen, Andreas; Hagen, W. T.; Harissopulos, Sotirios; Nyhus, Hilde Therese; Renstrom, T.; Schiller, Andreas; Siem, Sunniva; Tveten, G. M.; Voinov, A.; Wiedeking, M.

    2013-01-01

    The level densities and $\\gamma$-ray strength functions of $^{105,106,111,112}$Cd have been extracted from particle-$\\gamma$ coincidence data using the Oslo method. The level densities are in very good agreement with known levels at low excitation energy. The $\\gamma$-ray strength functions display no strong enhancement for low $\\gamma$ energies. However, more low-energy strength is apparent for $^{105,106}$Cd than for $^{111,112}$Cd. For $\\gamma$ energies above $\\approx$ 4 MeV, there is evid...

  3. Strength of Concrete Containing Basalt Fibre

    Directory of Open Access Journals (Sweden)

    Parvez Imraan Ansari

    2015-04-01

    Full Text Available This paper presents the comparative study of effect of basalt fibre on compressive and split tensile strength of M40 grade concrete. The basalt fibre was mixed in concrete by (0.5%, 1%, and 1.5% of its total weight of cement in concrete. Results indicated that the strength increases with increase of basalt fibre content up to 1.0% beyond that there is a reduction in strength on increasing basalt fibre. The results show that the concrete specimen with 1.0% of basalt fibre gives better performance when it compared with 0.5%and 1.5% basalt fibre mix in concrete specimens.

  4. Revealing the Maximum Strength in Nanotwinned Copper

    DEFF Research Database (Denmark)

    Lu, L.; Chen, X.; Huang, Xiaoxu;

    2009-01-01

    The strength of polycrystalline materials increases with decreasing grain size. Below a critical size, smaller grains might lead to softening, as suggested by atomistic simulations. The strongest size should arise at a transition in deformation mechanism from lattice dislocation activities to grain...... boundary–related processes. We investigated the maximum strength of nanotwinned copper samples with different twin thicknesses. We found that the strength increases with decreasing twin thickness, reaching a maximum at 15 nanometers, followed by a softening at smaller values that is accompanied by enhanced...

  5. Strength of Cracked Reinforced Concrete Disks

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1999-01-01

    The paper deals with models, based on the theory of plasticity, to be used in strength assessments of reinforced concrete disks suffering from different kinds of cracking. Based on the assumption that the sliding strength of concrete is reduced in sections where cracks are located, solutions for...... the shear strength of disks with initial cracks and disks suffering from isotropic cracking are presented. Furthermore, in the case of isotropicly cracked disks subjected to arbitrary in-plane loading, a general yield condition is derived....

  6. Laser Welding of High Strength Steels

    OpenAIRE

    Guo, Wei

    2016-01-01

    S960 and S700 are two types of high strength low alloy steels (minimum yield strengths at 960 MPa and 700 MPa, respectively) developed recently by Tata Steel. These steels are typically used in heavy lifting equipment. This research examines the feasibility and characteristics of single pass autogenous laser welding (ALW), multi-pass ultra-narrow gap laser welding (NGLW) of 8 mm thick S960 and 13 mm thick S700 high strength low alloy (HSLA) steels and compared the characteristics of the welds...

  7. Sources of strength-training information and strength-training behavior among Japanese older adults.

    Science.gov (United States)

    Harada, Kazuhiro; Shibata, Ai; Lee, Euna; Oka, Koichiro; Nakamura, Yoshio

    2016-03-01

    The promotion of strength training is now recognized as an important component of public health initiatives for older adults. To develop successful communication strategies to increase strength-training behavior among older adults, the identification of effective communication channels to reach older adults is necessary. This study aimed to identify the information sources about strength training that were associated with strength-training behaviors among Japanese older adults. The participants were 1144 adults (60-74 years old) randomly sampled from the registry of residential addresses. A cross-sectional questionnaire survey was conducted. The independent variables were sources of strength-training information (healthcare providers, friends, families, radio, television, newspapers, newsletters, posters, books, magazines, booklets, the Internet, lectures, other sources), and the dependent variable was regular strength-training behavior. Logistic regression analysis was used to identify potential relationships. After adjusting for demographic factors and all other information sources, strength-training information from healthcare providers, friends, books and the Internet were positively related to regular strength-training behavior. The findings of the present study contribute to a better understanding of strength-training behavior and the means of successful communication directed at increasing strength training among older adults. The results suggest that healthcare providers, friends, books and the Internet are effective methods of communication for increasing strength-training behaviors among older adults. PMID:24997193

  8. Strength Modeling of High-Strength Concrete with Hybrid Fibre Reinforcement

    Directory of Open Access Journals (Sweden)

    A. Ravichandran

    2009-01-01

    Full Text Available The low tensile strength and limited ductility, the unavoidable deficiency, of concrete can be overcome by the addition of fibres. High strength concrete (HSC of 60 MPa containing hybrid fibres, combination of steel and polyolefin fibres, at different volume fraction of 0.5, 1.0, 1.5 and 2.0% were compared in terms of compressive, splitting tensile strength and flexural properties with HSC containing no fibres. Test results showed that the fibres when used in hybrid form could result in enhanced flexural toughness compared to steel fibre reinforced concrete [HSFRC]. The compressive strength of the fibre-reinforced concrete reached maximum at 1.5% volume fractions and the splitting tensile strength and modulus of rupture improved with increasing volume fraction. Strength models were established to predict the compressive and splitting tensile strength and modulus of rupture of the fibre-reinforced concrete. The models give prediction matching the measurements.

  9. Indoor Air Quality Manual.

    Science.gov (United States)

    Baldwin Union Free School District, NY.

    This manual identifies ways to improve a school's indoor air quality (IAQ) and discusses practical actions that can be carried out by school staff in managing air quality. The manual includes discussions of the many sources contributing to school indoor air pollution and the preventive planning for each including renovation and repair work,…

  10. Air Pollution Training Programs.

    Science.gov (United States)

    Public Health Service (DHEW), Rockville, MD.

    This catalog lists the universities, both supported and not supported by the Division of Air Pollution, which offer graduate programs in the field of air pollution. The catalog briefly describes the programs and their entrance requirements, the requirements, qualifications and terms of special fellowships offered by the Division of Air Pollution.…

  11. Indoor air quality

    DEFF Research Database (Denmark)

    Jensen, Trine Susanne; Recevska, Ieva

     The objective of the 35th specific agreement is to provide support to the EEA activities in Environment and Health (E&H) on the topic of indoor air quality. The specific objectives have been to provide an overview of indoor air related projects in EU and indoor air related policies as well...

  12. Indoor Air Pollution

    Science.gov (United States)

    We usually think of air pollution as being outdoors, but the air in your house or office could also be polluted. Sources of indoor pollution ... is known as sick building syndrome. Usually indoor air quality problems only cause discomfort. Most people feel ...

  13. Air Travel Health Tips

    Science.gov (United States)

    MENU Return to Web version Air Travel Health Tips Air Travel Health Tips How can I improve plane travel? Most people don't have any problems when ... and dosages of all of your medicines. The air in airplanes is dry, so drink nonalcoholic, decaffeinated ...

  14. We Pollute the Air

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    1.Clean air is important to good health.If the aircontains impurities,they may be absorbed by ourbodies and make us ill.We need clean air,butunfortunately,air pollution is generally present,especially in cities. 2.Our cities have many factories,which we need tomake food products,clothing and many other things.

  15. Air pollution in China: Scientific and Public Policy Challenges

    Science.gov (United States)

    Zhu, T.

    2014-12-01

    Sever air pollution in China has in recent years caused intensive public, media and governmental attention. Many questions need to be answered about the air pollution in China, such as how harmful is the air pollution, especially PM2.5? Why suddenly so many reports about sever air pollution, is the air in China getting more polluted? How to design a policy that can control the air pollution most efficiently? After updated the national Ambient Air Quality Standards in 2012 and included PM2.5 as one of the critical air pollutants, in 2013, Chinese central government released for the first time the "Air Pollution Prevention and Control Action Plan". The plan has set goals to reduce annual mean concentration of PM2.5 up to 25% in 2017 in different regions in China. If the ambitious goals were achieved, this could be the most significant air pollution reduction in such a short time that affects so many people in human history. To achieve these goals, however, there are enormous scientific and public policy challenges to deal with. For example: Identify the key components, size fraction of PM that have the largest health effects; and identify the sources of PM that has the most harmful effects on human health and ecosystem. Reduce the uncertainty in health risk assessment. Understand complicate chemical transformation processes in air pollution formation with intensive emissions from industry, power plant, vehicles, agriculture. Interactions between air pollution, PBL, and atmospheric circulation at different scales. The accountability, feasibility, effectiveness, and efficiency of air pollution control policies. Integrate multi-pollutant control and achieve co-benefit with climate and energy policy. Regional coordinated air pollution control. The largest challenge in China for air pollution control remains how to strength the link between science and policy.

  16. Correlation between aggregate quality and compressive strength of andesite from Hungary

    Science.gov (United States)

    Czinder, Balázs; Török, Ákos

    2015-04-01

    Andesite is one of the most common lithology that is used as aggregate. Testing of aggregate quality traditionally includes Los Angeles, micro-Deval tests and the quality of the stone is assessed according to these values. In the present paper both aggregate properties and strength properties of andesites are compared in order to find correlation between aggregate strength, durability and compressive and tensile strength as well as frost resistance. Tests were made from andesite types obtained from two operating quarries of Nógrádkövesd and Gyöngyössolymos. Uniaxial compressive strength (UCS) values were compared with aggregate test results obtained from the same block. Air dry, water saturated and freeze-thaw subjected specimens were tested. According to lithological description and fabric analyses samples were grouped into 4 main lithotypes: one from Nógrádkövesd and three from Gyöngyössolymos. Fine porphyric andesite from Gyöngyössolymos provided the best micro-Deval values. In terms of uniaxial compressive strength the same trend was found, fine porphyric andesite from Gyöngyössolymos had the highest UCS under laboratory conditions, while coarser porphyritic andesite from the same quarry had lower strength. Water saturation decreased UCS as it was expected. Tensile strength values show a gradual deceases from air dry to water saturated and finally subjected to freeze-thaw cycles. Mean micro-Deval value of fine porphyric Gyöngyössolymos andesite was about 7, while that of the coarser porphyritic andesite was app. 16. These values are still higher than the mean micro-Deval test result of Nógrádkövesd andesite; which was 20. A good correlation was found in between Los Angeles and micro-Deval values, but there was no indication that micro-Deval values correlate well with UCS.

  17. The Effect of Different Surface Treatments on Flexural Strength and Modulus of Elasticity of Fiber Posts

    Directory of Open Access Journals (Sweden)

    MR Maleki pour

    2015-09-01

    Full Text Available ABSTRACT  Background and Aim: The aim of this study was to evaluate the effect of various surface treatments on flexural strength and modulus of elasticity of two different types of glass fiber and quartz fiber posts. Materials and Methods: In this experimental in vitro study eighty FRC posts of two different types: forty DT-light posts (quartz fiber and forty Whitepost DC (glass fiber, were used and randomly divided into 4 groups (n=10: 1. No surface treatment (control, 2. Laser irradiation, 3. Air-born particle abrasion, 4. Hydrogen peroxide 10%. To evaluate flexural strength and modulus of elasticity, 3-point bending test was performed in universal machine in Torabinejad searching center of dental school of Isfahan University and maximum fracture load was recorded. Then flexural strength and modulus of elasticity were calculated with formula. Data were analyzed by one-way ANOVA, Tukey and t tests.  Results: Before surface treatment the flexural strength and modulus of elasticity of DT- light posts were significantly higher that Withepost DC (p<0.05. There was no significant difference in flexural strength and modulus of elasticity between different groups of Withepost DC with control group (p=0.16 & p=0.15, respectively. But in DT-light posts there were statistical significant differences in flexural strength and modulus of elasticity only between air-abraded group and control. (p=0.02 & p=0.002, respectively  Conclusions: Surface pretreatments of glass and quartz fiber posts with laser and hydrogen peroxide 10% have no adverse effect on their flexural strength and modulus of elasticity. Key words: Fiber post, Surface Treatment, 3-Point Bending Test, elastic Modulus

  18. Turbulent vertical fluxes and air quality measured in urban air in Helsinki

    OpenAIRE

    JÀrvi, Leena

    2009-01-01

    There is a growing need to understand the exchange processes of momentum, heat and mass between an urban surface and the atmosphere as they affect our quality of life. Understanding the source/sink strengths as well as the mixing mechanisms of air pollutants is particularly important due to their effects on human health and climate. This work aims to improve our understanding of these surface-atmosphere interactions based on the analysis of measurements carried out in Helsinki, Finland. The v...

  19. Strength and stiffness of engineering systems

    CERN Document Server

    Leckie, Frederick A

    2009-01-01

    This book on the stiffness and strength of engineering systems integrates a wide array of topics into a unified text, including plasticity, fracture, composite materials, energy approaches, and mechanics of microdevices (MEMs)..

  20. STRENGTH DESIGN OF PREMIUM THREADED CASING CONNECTION

    Institute of Scientific and Technical Information of China (English)

    Gao Lianxin; Jin Ye; Zhang Yi

    2004-01-01

    Using premium casing connections instead of API ones is one of the most effective technique to prevent casing failure.The factors contribute to the strength of premium casing connections are studied with FEA and full-scale test.The criterions are presented that ensure the connection's strength higher than the pipe.At the same time, the method is given to decrease the peak stress of the connection so as to improve its anticorruption property.At last, full-scale tests are done to test the strength of the connections designed with the method described, the results show that the connection's strength is higher than the pipe.This indicated that the method described is effective in designing premium casing connection.

  1. Neural adaptations to electrical stimulation strength training

    NARCIS (Netherlands)

    Hortobagyi, Tibor; Maffiuletti, Nicola A.

    2011-01-01

    This review provides evidence for the hypothesis that electrostimulation strength training (EST) increases the force of a maximal voluntary contraction (MVC) through neural adaptations in healthy skeletal muscle. Although electrical stimulation and voluntary effort activate muscle differently, there

  2. Development of High Specific Strength Envelope Materials

    Science.gov (United States)

    Komatsu, Keiji; Sano, Masa-Aki; Kakuta, Yoshiaki

    Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured. 

  3. STRENGTH DETERMINATION OF ALUMINIUM AT DIFFERENT TEMPRATURES

    Directory of Open Access Journals (Sweden)

    Deepak Sharma

    2011-08-01

    Full Text Available The necking of specimen is specifically related to thedecrease in cross section when specimen is subjected totensile strength greater than ultimate tensile strength(UTS. The strain distribution no longer hold uniformalong the gauge length. As the tensile load is applied, dueto which length of specimen increases but there is decreasein cross section.The present work laid stress on determining the tensileproperties from stress strain curve by tensile testing ofaluminium (specimen at different range of hightemperature The tensile testing is carried out on INSTRONstatic series 600 KN. The specimens were tested atdifferent range of high temperature (Room Temperature -325 degree Celsius. True Stress and strain is calculatedusing the engineering equation. Using the values of truestress and true strain the true stress strain curve wasplotted. The polynomial equation is obtained from eachspecimen curve. The graph is plotted between temperatureand ultimate tensile strength (UTS which indicates thatthe ultimate tensile strength decreases with the increase intemperature.

  4. Nutritional Supplements for Strength Power Athletes

    Science.gov (United States)

    Wilborn, Colin

    Over the last decade research involving nutritional supplementation and sport performance has increased substantially. Strength and power athletes have specific needs to optimize their performance. Nutritional supplementation cannot be viewed as a replacement for a balanced diet but as an important addition to it. However, diet and supplementation are not mutually exclusive, nor does one depend on the other. Strength and power athletes have four general areas of supplementation needs. First, strength athletes need supplements that have a direct effect on performance. The second group of supplements includes those that promote recovery. The third group comprises the supplements that enhance immune function. The last group of supplements includes those that provide energy or have a direct effect on the workout. This chapter reviews the key supplements needed to optimize the performance and training of the strength athlete.

  5. Statistical Analysis of Data for Timber Strengths

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Hoffmeyer, P.

    Statistical analyses are performed for material strength parameters from approximately 6700 specimens of structural timber. Non-parametric statistical analyses and fits to the following distributions types have been investigated: Normal, Lognormal, 2 parameter Weibull and 3-parameter Weibull. The...

  6. An Investigation into Node Strength Connectivity Correlation

    Institute of Scientific and Technical Information of China (English)

    SHI Jian-Jun; WANG Yong-Li; HE Da-Ren

    2009-01-01

    We propose investigating the node strength connectivity correlation by a resource-allocation method and the traditional multiple edge method, respectively. A rough analysis suggests that the resource-allocation node strength connectivity correlation is always negative, which is different from the connectivity correlation of the traditional multiple edge node strength (it can show either positive, negative or no correlation). As examples,empirical investigation results for two real world cooperation-competition networks (the 2004 Athens Olympic Games network and the mixed drink network) are presented. We believe that the resource-allocation node strength connectivity correlation can serve as a description of the relative crackajack distribution, which is a complementarity of the traditional multiple edge one.

  7. Air Conditioning Does Reduce Air Pollution Indoors

    Science.gov (United States)

    Healy, Bud

    1970-01-01

    Report of the winter meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Subjects covered are--(1) title subject, (2) predictions for the human habitat in 1994, (3) fans, and (4) fire safety in buildings. (JW)

  8. Advanced air distribution

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor

    2011-01-01

    The aim of total volume air distribution (TVAD) involves achieving uniform temperature and velocity in the occupied zone and environment designed for an average occupant. The supply of large amounts of clean and cool air are needed to maintain temperature and pollution concentration at acceptable....... Ventilation in hospitals is essential to decrease the risk of airborne cross-infection. At present, mixing air distribution at a minimum of 12 ach is used in infection wards. Advanced air distribution has the potential to aid in achieving healthy, comfortable and productive indoor environments at levels...... higher than what can be achieved today with the commonly used total volume air distribution principles....

  9. Compressive Strength of Fibre Reinforced Concrete

    OpenAIRE

    Jelušič, Matjaž

    2009-01-01

    The thesis features an analysis of the time development of compressive strength of fibre reinforced normal and high strength concrete. Concrete mixtures, taken from the doctoral dissertation of assistant Dr Drago Saje, were used as comparable mixtures to fibre reinforced concrete mixtures with different volume shares of fibres. Two types of steel fibres were used, both featuring the same characteristics but having different lengths (16 and 30 mm), as well as polypropylene fibres. The percenta...

  10. Improvement of Cement Strength by Induction Method

    Institute of Scientific and Technical Information of China (English)

    YANG Li-yuan; LIN Zong-shou

    2004-01-01

    The induction method of improving the strength of Portland cement by adding fine slag powder,high aluminate component and hydrated paste was investigated through determining the physical properties,hydration heat and pore size distribution,and its mechanism was discussed.The experimental results reveal that a certain content of high aluminate component,fine slag powder and hydrated paste can improve remarkably the strength of Portland cement.

  11. Ultra-high–strength Bainitic Steels

    OpenAIRE

    García Mateo, Carlos; García Caballero, Francisca

    2005-01-01

    Novel bainitic microstructures, consisting of slender ferrite plates (tens of nm) in a matrix of retained austenite, have reported maximum yield strength of 1.4 GPa, ultimate tensile strength of 2.2 GPa, 30% ductility and respectable levels of fracture toughness (∼51 MPa m0.5). The unusual combination of properties is attributed to the fine bainitic plates and the presence of retained austenite in the microstructure.

  12. Assessment of Shear Strength in Silty Soils

    Directory of Open Access Journals (Sweden)

    Stefaniak Katarzyna

    2015-06-01

    Full Text Available The article presents a comparison of shear strength values in silty soils from the area of Poznań, determined based on selected Nkt values recommended in literature, with values of shear strength established on the basis of Nkt values recommended by the author. Analysed silty soils are characterized by the carbonate cementation zone, which made it possible to compare selected empirical coefficients both in normally consolidated and overconsolidated soils

  13. Hydrogen degradation of high-strength steels

    OpenAIRE

    J. Ćwiek

    2009-01-01

    Purpose: of this paper is to evaluate susceptibility of high-strength steels and welded joints to hydrogen degradation and to establish applicable mechanism of their hydrogen embrittlement and hydrogen delayed cracking.Design/methodology/approach: High-strength quenched and tempered steel grade S690Q and its welded joints have been used. Structural low-alloy steel 34CrAlNi7-10 with various plasma nitrided layers was evaluated. Susceptibility to hydrogen embrittlement of steel, welded joints, ...

  14. Psychrophilic anaerobic treatment of low strength wastewaters.

    OpenAIRE

    Rebac, S.

    1998-01-01

    The main objective of this thesis was to design a high-rate anaerobic system for the treatment low strength wastewaters under psychrophilic conditions.Psychrophilic (3 to 20 °C) anaerobic treatment of low strength synthetic and malting wastewater was investigated using a single and two stage expanded granular sludge bed (EGSB) reactor system. The chemical oxygen demand (COD) removal efficiencies found in the experiments with synthetic wastewater exceeded 90 % in the single stage reactor at im...

  15. Strength enhancement process for prealloyed powder superalloys

    Science.gov (United States)

    Waters, W. J.; Freche, J. C.

    1977-01-01

    A technique involving superplastic processing and high-pressure autoclaving was applied to a nickel-base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m (415 ksi) at 480 C (900 F) were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high-temperature tensile and stress-rupture strengths (980 C (1800 F)) were also devised.

  16. Strength of advanced ceramic laminated structures

    Czech Academy of Sciences Publication Activity Database

    Chlup, Zdeněk; Bermejo, R.; Hadraba, Hynek; Malíková, L.; Ševeček, O.; Danzer, R.; Dlouhý, Ivo

    Brno : Ústav fyziky materiálů AV ČR, v. v. i., 2015 - (Dlouhý, A.; Kunz, L.). s. 42-42 ISBN 978-80-87434-07-9. [ICSMA-17 International Conference on the Strength of Materials /17./. 09.08.2015-14.08.2015, Brno] Institutional support: RVO:68081723 Keywords : Strength * Laminates * Ceramics Subject RIV: JL - Materials Fatigue, Friction Mechanics

  17. Settings derivation for strength grading machines

    OpenAIRE

    Fortuna, Barbara

    2015-01-01

    A timber specimens highest strength grade for a selected strength grade combination can be determined by optimal grading. This can be achieved by different approaches that are represented in the current standard and pre-standard. The pre-standard defines a parametric and non-parametric calculation of characteristic properties from test results, which is the essential difference between various approaches. In both the non-parametric approach and the standard procedure, some simp...

  18. Strength and conditioning practices in rowing

    OpenAIRE

    Gee, Thomas I.; Olsen, Peter D.; Berger, Nicolas J.; Golby, Jim; Thompson, Kevin G.

    2011-01-01

    There is limited published research on the practices of strength and conditioning (S &C) coaches in Great Britain. Information about training program design would be useful in developing models of good practice and ecologically valid intervention studies. The aim of this research was to quantify the training practices of coaches responsible for the S&C of rowing athletes. A questionnaire was developed that consisted of 6 sections: (a) personal details, (b) physical testing, (c) strength and p...

  19. COMPRESSIVE STRENGTH CHARACTERISTICS OF TILE WASTE CONCRETE

    OpenAIRE

    Ofonime A. Harry*, Ifiok E. Ekop

    2016-01-01

    Increase in the use of concrete in construction industry in Nigeria has led to the rise in the cost of its constituent material. This has necessitated research into the use of alternative material which is cheaper and can produce a comparable level of strength as the conventionally used ones. This paper present the results of an investigation into the compressive strength characteristics of concrete made with ceramic tile waste as coarse aggregates. The percentage of tile waste was varied in ...

  20. Direct analysis of air filter samples for alpha emitting isotopes

    International Nuclear Information System (INIS)

    The traditional method for determination of alpha emitting isotopes on air filters has been to process the samples by radiochemical methods. However, this method is too slow for cases of incidents involving radioactive materials where the determination of personnel received dose is urgent. A method is developed to directly analyze the air filters taken from personal and area air monitors. The site knowledge is used in combination with alpha spectral information to identify isotopes. A mathematical function is developed to estimate the activity for each isotope. The strengths and weaknesses of the method are discussed

  1. Released air during vapor and air cavitation

    Science.gov (United States)

    Jablonská, Jana; Kozubková, Milada

    2016-06-01

    Cavitation today is a very important problem that is solved by means of experimental and mathematical methods. The article deals with the generation of cavitation in convergent divergent nozzle of rectangular cross section. Measurement of pressure, flow rate, temperature, amount of dissolved air in the liquid and visualization of cavitation area using high-speed camera was performed for different flow rates. The measurement results were generalized by dimensionless analysis, which allows easy detection of cavitation in the nozzle. For numerical simulation the multiphase mathematical model of cavitation consisting of water and vapor was created. During verification the disagreement with the measurements for higher flow rates was proved, therefore the model was extended to multiphase mathematical model (water, vapor and air), due to release of dissolved air. For the mathematical modeling the multiphase turbulence RNG k-ɛ model for low Reynolds number flow with vapor and air cavitation was used. Subsequently the sizes of the cavitation area were verified. In article the inlet pressure and loss coefficient depending on the amount of air added to the mathematical model are evaluated. On the basis of the approach it may be create a methodology to estimate the amount of released air added at the inlet to the modeled area.

  2. Approaching theoretical strength in glassy carbon nanolattices

    Science.gov (United States)

    Bauer, J.; Schroer, A.; Schwaiger, R.; Kraft, O.

    2016-04-01

    The strength of lightweight mechanical metamaterials, which aim to exploit material-strengthening size effects by their microscale lattice structure, has been limited by the resolution of three-dimensional lithography technologies and their restriction to mainly polymer resins. Here, we demonstrate that pyrolysis of polymeric microlattices can overcome these limitations and create ultra-strong glassy carbon nanolattices with single struts shorter than 1 μm and diameters as small as 200 nm. They represent the smallest lattice structures yet produced--achieved by an 80% shrinkage of the polymer during pyrolysis--and exhibit material strengths of up to 3 GPa, corresponding approximately to the theoretical strength of glassy carbon. The strength-to-density ratios of the nanolattices are six times higher than those of reported microlattices. With a honeycomb topology, effective strengths of 1.2 GPa at 0.6 g cm-3 are achieved. Diamond is the only bulk material with a notably higher strength-to-density ratio.

  3. Elastic stability and the limit of strength

    Energy Technology Data Exchange (ETDEWEB)

    Morris Jr., J.W.; Krenn, C.R.; Roundy, D.; Cohen, Marvin L.

    2002-07-01

    The upper limit of strength (the ''theoretical strength'') has been an active subject of research and speculation for the better part of a century. The subject has recently become important, for two reasons. First, given recent advances in ab initio techniques and computing machines, the limits of strength can be calculated with considerable accuracy, making this one of the very few problems in mechanical behavior that can actually be solved. Second, given recent advances in materials engineering, the limits of strength are being approached in some systems, such as hardened or defect-free films, and their relevance is becoming recognized in others. The present paper discusses some interesting results from recent research on the limits of strength, with an intermixture of speculations based on those results. Topics include the inherent nature of {l_brace}100{r_brace} cleavage and ''pencil slip'' in bcc metals, the inherent ductility of fcc metals, the anomalous properties of Al, and the possibility of measuring ideal strength with nanoindentation.

  4. WET STRENGTH PAPER REPULPING: LABORATORY EVALUATION

    Institute of Scientific and Technical Information of China (English)

    NishiK.Bhardwaj; VikasRajan; A.G.Kulkarni

    2004-01-01

    The recycling of wet strength papers in a normal recycling mill is often troublesome due to the severe operating conditions required to defibre wet strength papers. The various methods are presented which will quickly allow mills to determine the most effective pulping aids to use when repulping wet strength papers. The repulping of wet strength paper with inorganic chemicals was investigated in the laboratory. The effects of major variables, that is, repulping time, pulp consistency, soaking time, temperature, and reactant concentration in the repulping stage were examined using Plackett-Burman design. The repulping time was the most crucial & influential process variable affecting repulping characteristic and formation related properties. The more significant repulping process variables affecting pulp yield were repulping time, soaking temperature and pulp consistency whereas for formation index and feature size, repulping time, pulp consistency, soaking temperature and time were the more important variables. The formation index is increased by an increase in repulping time, pulp consistency and soaking time whereas the feature size is decreased by an increase in repulping time, soaking temperature and pulp consistency. The formation index and the rejects were more sensitive to changes in process variables than were the feature size or the pulp yield. The pulp recycled from wet strength waste paper had good physical strength properties.

  5. WET STRENGTH PAPER REPULPING:LABORATORY EVALUATION

    Institute of Scientific and Technical Information of China (English)

    Nishi K. Bhardwaj; Vikas Rajan; A.G. Kulkarni

    2004-01-01

    The recycling of wet strength papers in a normal recycling mill is often troublesome due to the severe operating conditions required to defibre wet strength papers. The various methods are presented which will quickly allow mills to determine the most effective pulping aids to use when repulping wet strength papers. The repulping of wet strength paper with inorganic chemicals was investigated in the laboratory. The effects of major variables, that is,repulping time, pulp consistency, soaking time,temperature, and reactant concentration in the repulping stage were examined using Plackett-Burman design. The repulping time was the most crucial & influential process variable affecting repulping characteristic and formation related properties. The more significant repulping process variables affecting pulp yield were repulping time,soaking temperature and pulp consistency whereas for formation index and feature size, repulping time,pulp consistency, soaking temperature and time were the more important variables. The formation index is increased by an increase in repulping time, pulp consistency and soaking time whereas the feature size is decreased by an increase in repulping time,soaking temperature and pulp consistency. The formation index and the rejects were more sensitive to changes in process variables than were the feature size or the pulp yield. The pulp recycled from wet strength waste paper had good physical strength properties.

  6. Strength functions for fragmented doorway states

    International Nuclear Information System (INIS)

    Coupling a strongly excited ''doorway state'' to weak ''hallway states'' distributes its strength into micro-resonances seen in differential cross sections taken with very good energy resolution. The distribution of strength is shown to be revealed by reduced widths of the K-matrix rather than by the imaginary part of poles of the S-matrix. Different strength functions (SF) constructed by averaging the K-matrix widths are then investigated to determine their dependences on energy and on parameters related to averages of microscopic matrix elements. A new sum rule on the integrated strength of these SF is derived and used to show that different averaging procedures actually distribute the strength differently. Finally, it is shown that the discontinuous summed strength defines spreading parameters for the doorway state only in strong coupling, where it approximates the idefinite integral of the continuous SF of MacDonald-Mekjian-Kerman-De Toledo Piza. A new method of ''parametric continuation'' is used to relate a discontinuous sliding box-average, or a finite sum, of discrete terms to a continous function

  7. Strength gradient enhances fatigue resistance of steels

    Science.gov (United States)

    Ma, Zhiwei; Liu, Jiabin; Wang, Gang; Wang, Hongtao; Wei, Yujie; Gao, Huajian

    2016-02-01

    Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch’s tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.

  8. Increasing Lean Mass and Strength: A Comparison of High Frequency Strength Training to Lower Frequency Strength Training

    Science.gov (United States)

    THOMAS, MICHAEL H.; BURNS, STEVE P.

    2016-01-01

    The purpose of this study was to determine the effect strength training frequency has on improvements in lean mass and strength. Participants were 7 women and 12 men, age (χ̄= 34.64 years ± 6.91 years), with strength training experience, training age (χ̄= 51.16 months ± 39.02 months). Participants were assigned to one of two groups to equal baseline group demographics. High frequency training group (HFT) trained each muscle group as the agonist, 3 times per week, exercising with 3 sets per muscle group per session (3 total body workouts). Low frequency training group (LFT) trained each muscle group as the agonist one time per week, completing all 9 sets during that one workout. LFT consisted of a routine split over three days: 1) pectoralis, deltoids, and triceps; 2) upper back and biceps; 3) quadriceps, hamstrings, calves, and abdominals. Following eight weeks of training, HFT increased lean mass by 1.06 kg ± 1.78 kg, (1.9%), and LFT increased lean mass by .99 kg ± 1.31 kg, (2.0%). HFT strength improvements on the chest press was 9.07 kg ± 6.33 kg, (11%), and hack squat 20.16 kg ± 11.59 kg, (21%). LFT strength improvements on chest press was 5.80kg ± 4.26 kg, (7.0%), and hack squat 21.83 kg ± 11.17 kg, (24 %). No mean differences between groups were significant. These results suggest that HFT and LFT of equal set totals result in similar improvements in lean mass and strength, following 8 weeks of strength training.

  9. The role of polymer in improving floc strength for filtration.

    Science.gov (United States)

    Fabrizi, Lara; Jefferson, Bruce; Parsons, Simon A; Wetherill, Andrew; Jarvis, Peter

    2010-08-15

    Dosing polymer to improve floc characteristics is a widely practiced method in water treatment to improve floc strength, and there is strong operational evidence showing the benefit of polymer dosing. However, there is a paucity of information on how polymer operates in terms of quantifying the resulting floc size and strength over different size scales. A dual particle sizing approach was used to monitor large floc that contain most of the sludge volume and small floc that can cause downstream treatability problems for systems with and without polymer dosing. The polymer investigated was a slightly anionic polyacrylamide dosed in water collected post dissolved air flotation at concentrations of 0-0.03 mg L(-1). With increasing polymer dose, median floc size increased from 228 to 325 microm. Floc responses to increased shear rate showed that polymer dosing increased resistance to floc break-up. While all of the flocs showed high potential to regrow, regrowth was greatest in polymer-dosed systems, where flocs exceeded the size that they had reached previously. Increasing the dose of polymer showed increased removal of small particles (<8 microm) showing that polymer was able to effectively remove particles that are liable to cause downstream problems. PMID:20669902

  10. Manual for THOR-AirPAS - air pollution assessment system

    DEFF Research Database (Denmark)

    Jensen, Steen Solvang; Ketzel, Matthias; Brandt, Jørgen;

    The report provides an outline of the THOR-AirPAS - air pollution assessment system and a brief manual for getting started with the air quality models and input data included in THOR-AirPAS.......The report provides an outline of the THOR-AirPAS - air pollution assessment system and a brief manual for getting started with the air quality models and input data included in THOR-AirPAS....

  11. Radiation dosage during pediatric diagnostic or interventional cardiac catheterizations using the "air gap technique" and an aggressive "as low as reasonably achievable" radiation reduction protocol in patients weighing < 20 kg

    Directory of Open Access Journals (Sweden)

    Frank A Osei

    2016-01-01

    Results: One-hundred and twenty-seven patients underwent 151 procedures within the study period. The median age was 1.2 years (range: 1 day to 7.9 years and median weight was 8.8 kg (range: 1.9-19.7. Eighty-nine (59% of the procedures were interventional. The median total fluoro time was 13 min [interquartile range (IQR 7.3-21.8]. The median total air Kerma (K product was 55.6 mGy (IQR 17.6-94.2 and dose area product (DAP was 189 Gym2 (IQR 62.6-425.5. Conclusion: Use of a novel ALARA and AGT protocol for cardiac catheterizations in children markedly reduced radiation exposure to levels far below recently reported values.

  12. Experimental Investigation into Pull-Out Strength of Foamed Concrete Using Different Types of Screw

    Directory of Open Access Journals (Sweden)

    Othuman Mydin M.A.

    2014-01-01

    Full Text Available This study focuses on the results of the comprehensive strength test to quantify the mechanical properties of the screw’s pullout strength on foamed concrete. Foamed concrete is classified as lightweight concrete that been produced by cement paste or mortar in which air-voids are entrapped in the mortar by a suitable foaming agent. These days, the use of foamed concrete has been recognized in the construction industry as wall blocks, wall panels and also material floor and roof screeds. Hence, the applications of this material should be maximized as it is multi-functional. As we know, the use of screws on the wall or ceiling is common in a building. The objective of this research is to examine and determine the pullout strength of various properties and types of screws in lightweight foamed concrete with various densities that may depict the best result of the pullout strength on foamed concrete. To visualize the different results of pullout strength, screws with and without wall plug will be used as well. The pullout strength will be tested using the Universal Testing Machine where it shall measure the ultimate load of the screws attached to the foamed concrete may resist.

  13. Soil-roots Strength Performance of Extensive Green Roof by Using Axonopus Compressus

    Science.gov (United States)

    Yusoff, N. A.; Ramli, M. N.; Chik, T. N. T.; Ahmad, H.; Abdullah, M. F.; Kasmin, H.; Embong, Z.

    2016-07-01

    Green roof technology has been proven to provide potential environmental benefits including improved building thermal performance, removal of air pollution and reduced storm water runoff. Installation of green roof also involved soil element usage as a plant growth medium which creates several interactions between both strands. This study was carried out to investigate the soil-roots strength performance of green roof at different construction period up to 4 months. Axonopus compressus (pearl grass) was planted in a ExE test plot with a designated suitable soil medium. Direct shear test was conducted for each plot to determine the soil shear strength according to different construction period. In addition, some basic geotechnical testing also been carried out. The results showed that the shear strength of soil sample increased over different construction period of 1st, 2nd, 3rd and 4th month with average result 3.81 kPa, 5.55 kPa, 6.05 kPa and 6.48 kPa respectively. Shear strength of rooted soil samples was higher than the soil samples without roots (control sample). In conclusion, increment of soil-roots shear strength was due to root growth over the time. The soil-roots shear strength development of Axonopus compressus can be expressed in a linear equation as: y = 0.851x + 3.345, where y = shear stress and x = time.

  14. Shear Bond Strength of MDP-Containing Self-Adhesive Resin Cement and Y-TZP Ceramics: Effect of Phosphate Monomer-Containing Primers

    Directory of Open Access Journals (Sweden)

    Jin-Soo Ahn

    2015-01-01

    Full Text Available Purpose. This study was conducted to evaluate the effects of different phosphate monomer-containing primers on the shear bond strength between yttria-tetragonal zirconia polycrystal (Y-TZP ceramics and MDP-containing self-adhesive resin cement. Materials and Methods. Y-TZP ceramic surfaces were ground flat with #600-grit SiC paper and divided into six groups (n=10. They were treated as follows: untreated (control, Metal/Zirconia Primer, Z-PRIME Plus, air abrasion, Metal/Zirconia Primer with air abrasion, and Z-PRIME Plus with air abrasion. MDP-containing self-adhesive resin cement was applied to the surface-treated Y-TZP specimens. After thermocycling, a shear bond strength test was performed. The surfaces of the Y-TZP specimens were analyzed under a scanning electron microscope. The bond strength values were statistically analyzed using one-way analysis of variance and the Student–Newman–Keuls multiple comparison test (P<0.05. Results. The Z-PRIME Plus treatment combined with air abrasion produced the highest bond strength, followed by Z-PRIME Plus application, Metal/Zirconia Primer combined with air abrasion, air abrasion alone, and, lastly, Metal/Zirconia Primer application. The control group yielded the lowest results (P<0.05. Conclusion. The application of MDP-containing primer resulted in increased bond strength between Y-TZP ceramics and MDP-containing self-adhesive resin cements.

  15. Notched Strength Allowables and Inplane Shear Strength of AS4/VRM-34 Textile Laminates

    Science.gov (United States)

    Grenoble, Ray W.; Johnston, William M.

    2013-01-01

    Notched and unnotched strength allowables were developed for a textile composite to provide input data to analytical structural models based on the Pultruded Rod Stiffened Efficient Unitized Structure (PRSEUS) concept. Filled-hole tensile strength, filled-hole compressive strength, and inplane shear strength along stitch lines have been measured. The material system evaluated in this study is based on warp-knitted preforms of AS4 carbon fibers and VRM-34 epoxy resin, which have been processed via resin infusion and oven curing. All specimens were tested in as-fabricated (dry) condition. Filled-hole strengths were evaluated with and without through-thickness stitching. The effects of scaling on filled-hole tensile strength were evaluated by testing specimens in two widths, but with identical width / hole-diameter ratios. Inplane shear specimens were stitched in two configurations, and two specimen thicknesses were tested for each stitch configuration.

  16. Strength Regularity and Failure Criterion of High-Strength High-Performance Concrete under Multiaxial Compression

    Institute of Scientific and Technical Information of China (English)

    HE Zhen-jun; SONG Yu-pu

    2008-01-01

    Multiaxial compression tests were performed on 100 mm × 100 mm × 100 nun high-strength high-performance concrete (HSHPC) cubes and normal strength concrete (NSC) cubes. The failure modes of specimens were presented, the static compressive strengths in principal directions were measured, the influence of the stress ratios was analyzed. The experimental results show that the ultimate strengths for HSHPC and NSC under multiaxial compression are greater than the uniaxial compressive strengths at all stress ratios, and the multiaxial strength is dependent on the brittleness and stiffness of concrete, the stress state and the stress ratios. In addition, the Kupfer-Gerstle and Ottosen's failure criteria for plain HSHPC and NSC under multiaxial compressive loading were modified.

  17. Mechanical strength of adhesive-bonding

    International Nuclear Information System (INIS)

    In order to meet the prospective application of a GFRP dewar for energy storage system using a large superconducting magnet, the dewar with a complex structure together with a large size are desired to be made. It is difficult to manufacture such a type of the dewars in one united body. These dewars can be manufactured by the adhesive-bonding method. In the present study, the mechanical strength of adhesive-bonding is studied from this point of view. The mechanical strength of the adhesive-bonding has been investigated by the static tensile method and the impact loading method using small test samples. From the static tensile tests, the following results have been obtained. For the sample adhesive-bonded with insertion structure, the mechanical strength of the adhesive-bonding is found to depend on the adhesives used and on the difference of the thermal contraction between the materials which are adhesive-bonded each other. Using a soft adhesive as Araldite 106, the mechanical strength of the adhesive-bonding is small at room temperature, but it remarkably increases at cryogenic temperatures. For a hard adhesive as Araldite 103 and Stycast 2850 FT, it is large at room temperature, and it further increases at cryogenic temperatures. The dewar has to be strong enough not only at cryogenic temperatures but also at room temperature. A soft adhesive is not suitable for constructing the dewar. For the sample adhesive-bonded with screwing structure, the mechanical strength of the adhesive-bonding depends on the shear strength of GFRP itself. The mechanical strength of the adhesive-bonded part increases with the decreasing temperature. Therefore, this screwing method is advantageous for the construction of the dewar. According to the impact loading tests, it is found that the adhesive-bonding of screwing structure is not brittle at cryogenic temperature. This is due to inherent property of GFRP. (J.P.N.)

  18. EFFECTS OF STRENGTH TRAINING ON PHYSICAL FUNCTION: INFLUENCE OF POWER, STRENGTH, AND BODY COMPOSITION

    OpenAIRE

    Hanson, Erik D.; Srivatsan, Sindhu R.; Agrawal, Siddhartha; Menon, Kalapurakkal S.; Delmonico, Matthew J.; Wang, Min Q.; Hurley, Ben F.

    2009-01-01

    The purpose of this study was to determine (a) the effects of strength training (ST) on physical function and (b) the influence of strength, power, muscle volume (MV), and body composition on physical function. Healthy, inactive adults (n = 50) aged 65 years and older underwent strength, power, total body composition (% fat and fat free mass [FFM]), and physical function testing before and after 22 weeks of ST. Physical function testing consisted of tasks designed to mimic common physical act...

  19. EFFECT OF NATURAL ZEOLITE ON THE COMPRESSIVE STRENGTH AND FREEZE-THAW RESISTANCE OF PORTLAND CEMENT

    OpenAIRE

    Bayartsetseg, E.; Lkhagvajargal, G.; Batgerel, D.; Sarangerel, D.; Ochirkhuyag, B

    2011-01-01

    Effects of zeolites in various natural deposits as replacement cementing material on mechanical performance of Portland cement were studied. The blended cement pastes with zeolites were cured at room temperature in air for various durations (1, 7 and 28 days). Mechanical performance of the blended cement samples such as setting time, volume of water, compressive strength, normal consistency and freeze-thaw resistance of the mortar are determined. The optimal substitution ratio was 20 wt. % of...

  20. 信息动态%Size Effect on Strength of Ultra-high Strength Concrete RPC

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Reactive Powder Concrete (RPC)is a new kind of ultra-high strength cement based composite with excellent mechanics performance and durability. In order to make RPC used in structural engineering effectively,size effect on strength of the ultra high strength concrete RPC specimen is experimental studied and the mechanism is analyzed in this paper. Test results show that if the 4 cm cube compressive strength is the control strength,conversion coefficients of 10 em cube compressive strength at 150 MPa and 200 MPa grade are 0.81 and 0.76 respectively; conversion coefficients of 10 cm× 10 cm× 30 cm prism compressive strength at 150 MPa and 200 MPa grade are 0.71 and 0. 63 respectively; the size effect conversion coefficient tends to decrease with the increase of control strength, the larger the specimen size, the lower the compressive strength. RPC is a typical brittle material. It extends instability quickly after cracking;damage concentrated in the local area,and therefore appears higher size effect.