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Sample records for air kerma strength

  1. 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...

  2. 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

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

    Science.gov (United States)

    Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

    2014-11-01

    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.

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

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    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)

  5. Air Kerma Rate estimation by means of in-situ gamma spectrometry: a Bayesian approach.

    Science.gov (United States)

    Cabal, Gonzalo; Kluson, Jaroslav

    2010-01-01

    Bayesian inference is used to determine the Air Kerma Rate based on in-situ gamma spectrum measurement performed with an NaI(Tl) scintillation detector. The procedure accounts for uncertainties in the measurement and in the mass energy transfer coefficients needed for the calculation. The WinBUGS program (Spiegelhalter et al., 1999) was used. The results show that the relative uncertainties in the Air Kerma estimate are of about 1%, and that the choice of unfolding procedure may lead to an estimate systematic error of 3%.

  6. Air Kerma Rate estimation by means of in-situ gamma spectrometry: A Bayesian approach

    Energy Technology Data Exchange (ETDEWEB)

    Cabal, Gonzalo [Department of Dosimetry and Applications of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic); Department of Radiation Dosimetry, Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Na Truhlarce 39/64, 180 86 Prague 8 (Czech Republic)], E-mail: cabal@ujf.cas.cz; Kluson, Jaroslav [Department of Dosimetry and Applications of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Prague 1 (Czech Republic)

    2010-04-15

    Bayesian inference is used to determine the Air Kerma Rate based on in-situ gamma spectrum measurement performed with an NaI(Tl) scintillation detector. The procedure accounts for uncertainties in the measurement and in the mass energy transfer coefficients needed for the calculation. The WinBUGS program () was used. The results show that the relative uncertainties in the Air Kerma estimate are of about 1%, and that the choice of unfolding procedure may lead to an estimate systematic error of 3%.

  7. Comparison of air kerma area product and air kerma meter calibrations for X-ray radiation qualities used in diagnostic radiology

    Science.gov (United States)

    Hourdakis, C. J.; Csete, I.; Daures, J.; Jarvinen, H.; Mihailescu, L.-C.; Sochor, V.; Novak, L.; Pedersen, M.; Kosunen, A.; Toroi, P.; Denoziere, M.; Büermann, L.; Megzifene, A.; Einarsson, G.; Ferrari, P.; dePooter, J.; Bjerke, H.; Brodecki, M.; Cardoso, J.; Bercea, S.; Ciraj-Bjelac, O.; Compel, J.; Glavič-Cindro, D.; Ginjaume, M.; Persson, L.; Grindborg, J.-E.

    2015-01-01

    The EURAMET #1177 project, identified as EURAMET RI(I) - S9 comparison, was the first EURAMET wide scale supplementary comparison in the field of diagnostic radiology for air kerma area product, PKA, and air kerma, K. It was conducted with the goal of testing the measurement and calibration capabilities for PKA and K, as well as of supporting the relevant CMCs of the participating laboratories. Two commercial KAP meters and an ionization chamber were selected as transfer instruments and circulated between the 22 European participants. The measurements were performed from April 2011 until July 2012. The stability and the performance of the transfer instruments were tested by the pilot laboratory (IRCL/GAEC-EIM) and few other laboratories as well. The test results revealed that the energy (radiation quality), Q, irradiation area, A, and air kerma rate, dot K dependences of response of the transfer KAP meters influence the comparison of the results when different measurement conditions were pertained and therefore, appropriate correction factors were obtained and applied to the reported calibration results of the laboratories, when necessary. The comparison reference values (CRVs) for each instrument were determined as the weighted mean of the calibration coefficients of the three participating primary laboratories. The relative standard uncertainty of the CRVs were in the range of (0.4 - 1.6)% depending on the transfer instruments and beam qualities. The comparison result as the ratio of the corrected calibration coefficient of participant and the respective CRV, and its uncertainty were calculated for all beam qualities and transfer instruments. The informative degrees of equivalence (DoE) were calculated for the refrence RQR 5 beam quality. In case of air kema area product measurements the results for the RADCAL PDC KAP meter were used. The 216 KAP meter calibration results of the two different transfer instruments in terms of air kerma area product were consistent

  8. Air-kerma determination using a variable-volume cavity ionization chamber standard.

    Science.gov (United States)

    Burns, D T; Kessler, C; Roger, P

    2007-12-01

    A graphite-walled cavity ionization chamber of modular design and variable volume has been used to determine the air-kerma rate in the reference 60Co field at the BIPM. The chamber can be configured in five sizes. High-accuracy mechanical measurements of the volume of the air cavity were made for each configuration using a co-ordinate measuring machine. Ionization current measurements were made for each configuration and corrected for the effects of ion recombination and diffusion, stem scatter and chamber orientation. Monte Carlo calculations of cavity dose were made to evaluate the correction factors kwall and kan. A reproducibility of the ionization current per mass of 1.5 parts in 10(4) was achieved on the repeated assembly of each configuration. The results show an air-kerma rate determination that increases with volume, the total change being around 8 parts in 10(4). When analysed differentially, the air-kerma rate relative to the BIPM standard is Kdiff/KBIPM = 1.0026(6). A detailed uncertainty budget is presented. Possible reasons for the observed behaviour are discussed that might have consequences for all existing standards for air-kerma.

  9. 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)

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

    Directory of Open Access Journals (Sweden)

    V. P. Ramzaev

    2015-01-01

    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. 

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

    Energy Technology Data Exchange (ETDEWEB)

    Damatto, Willian Behling; Potiens, Maria da Penha A.; Vivolo, Vitor, E-mail: willbdamatto@gmail.com [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    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)

  12. 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.

  13. Study of the indirect calibration of clinical air kerma-area meters; Estudo da calibracao indireta de medidores clinicos do produto kerma-area

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Jose N. [Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil). Curso de Fisica Medica; Silva, Marcia C. [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil); Terini, Ricardo A., E-mail: rterini@pucsp.b [Pontificia Univ. Catolica de Sao Paulo (DF/PUC/SP), SP (Brazil). Dept. de Fisica; Herdade, Silvio B. [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Inst. de Eletrotecnica e Energia. Secao Tecnica de Desenvolvimento Tecnologico em Saude Marco A.G. Pereira

    2011-07-01

    Kerma-area product (P{sub KA}) is a quantity which is independent of the distance to the X-ray tube focal spot and that can be used to assess the effective dose in patients. Clinical P{sub KA} meters are usually calibrated on-site by measuring the air kerma with an ion chamber and evaluating the irradiated area by means of a radiographic image. This work presents a preliminary metrological evaluation of the calibration of a device marketed recently (PDC, Patient Dose Calibrator, Radcal), designed for calibrating clinical P{sub KA} meters. Results are also shown of applying the PDC to the cross calibration of a clinical P{sub KA} meter from a radiology equipment. Results confirm a lower energy dependence of the PDC relative to the tested clinical meter. (author)

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

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    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)

  15. 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.

  16. Measurements of air kerma index in computed tomography: a comparison among methodologies

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    Alonso, T. C.; Mourao, A. P.; Da Silva, T. A., E-mail: alonso@cdtn.br [Universidade Federal de Minas Gerais, Programa de Ciencia y Tecnicas Nucleares, Av. Pres. Antonio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

  17. Primary Beam Air Kerma Dependence on Distance from Cargo and People Scanners

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    Strom, Daniel J.; Cerra, Frank

    2016-06-01

    The distance dependence of air kerma or dose rate of the primary radiation beam is not obvious for security scanners of cargo and people in which there is relative motion between a collimated source and the person or object being imaged. To study this problem, one fixed line source and three moving-source scan-geometry cases are considered, each characterized by radiation emanating perpendicular to an axis. The cases are 1) a stationary line source of radioactive material, e.g., contaminated solution in a pipe; 2) a moving, uncollimated point source of radiation that is shuttered or off when it is stationary; 3) a moving, collimated point source of radiation that is shuttered or off when it is stationary; and 4) a translating, narrow “pencil” beam emanating in a flying-spot, raster pattern. Each case is considered for short and long distances compared to the line source length or path traversed by a moving source. The short distance model pertains mostly to dose to objects being scanned and personnel associated with the screening operation. The long distance model pertains mostly to potential dose to bystanders. For radionuclide sources, the number of nuclear transitions that occur a) per unit length of a line source, or b) during the traversal of a point source, is a unifying concept. The “universal source strength” of air kerma rate at a meter from the source can be used to describe x-ray machine or radionuclide sources. For many cargo and people scanners with highly collimated fan or pencil beams, dose varies as the inverse of the distance from the source in the near field and with the inverse square of the distance beyond a critical radius. Ignoring the inverse square dependence and using inverse distance dependence is conservative in the sense of tending to overestimate dose.

  18. Rate air Kerma entrance skin of patients undergoing hemodynamic procedures in the State of Santa Catarina, Brazil; Taxa de Kerma no ar na entrada da pele de pacientes submetidos a procedimentos hemodinamicos no Estado de Santa Catarina

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    Queiroz, Carlos Eduardo B.; Grechi, Bruna E.; Hahn, Tiago T.; Dalcin, Rodrigo C.; Augusto, Israel J.; Bolzan, Vagner; Jahn, Tiago R.; Gerber Junior, Walmoli, E-mail: brasilrad@brasilrad.com.br [Brasilrad - Consultoria em Radioprotecao, Florianopolis, SC (Brazil)

    2013-12-15

    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)

  19. 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

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    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)

  20. Comparison of the standards for air kerma of the NRC and the BIPM for {sup 60}Co gamma radiation

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    Kessler, C.; Allisy, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McCaffrey, J.P.; Ross, C.K. [National Research Council (Canada)

    2010-02-15

    An indirect comparison of the standards for air kerma of the National Research Council (NRC), Canada, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 60}Co radiation beam of the BIPM in May 2009. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NRC and the BIPM standards for air kerma, is 1.0032 with a combined standard uncertainty of 2.8 * 10{sup -3}. The result of the previous direct comparison in {sup 60}Cogamma rays, made in 1998 and modified in 2007 was 1.0025 (27). The degrees of equivalence between the NRC and the other participants in the key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. (authors)

  1. Determination of air kerma standard of high dose rate {sup 192}Ir brachytherapy source; Determinacao da taxa de kerma no ar de referencia para {sup 192}Ir de alta taxa de dose para braquiterapia

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    Pires, E.J.; Alves, C.F.E.; Leite, S.P.; Magalhaes, L.A.G.; David, M.G.; Almeida, C.E. de, E-mail: cfealves@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Lab. de Ciencias Radiologicas; Di Prinzio, R. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    This paper presents the methodology developed by the Laboratorio de Ciencias Radiologicas and presently in use for determining of the air kerma standard of {sup 192}Ir high dose rate sources to calibrate well-type chambers. Uncertainty analysis involving the measurements procedure are presented. (author)

  2. 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)

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

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    1997-01-01

    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 kerma rates; by having a large fraction of the ground level gamma-rays at energies below 350 keV special care should be taken at an interpretation of the results....

  4. 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)

  5. APMP key comparison for the measurement of air kerma for 60Co (APMP.RI(I)-K1.1)

    Science.gov (United States)

    Webb, D. V.; Lee, J.-H.; Budiantari, C. T.; Laban, J.; Saito, N.; Srimanoroth, S.; Khaled, N. E.

    2016-01-01

    The results are reported for an APMP.R(I)-K1.1 comparison that extends the regional comparison of standards for air kerma APMP.R(I)-K1 to several laboratories unable to participate earlier. The comparison was conducted with the goal of supporting the relevant calibration and measurement capabilities (CMCs) planned for publication by the participant laboratories. The comparison was conducted by the pilot laboratory, the Australian Radiation Protection and Nuclear Safety (ARPANSA), Australia, supported by the Institute of Nuclear Energy Research (INER), Taiwan, in a modified ring-shaped arrangement from September 2009 to November 2010, in parallel with an APMP.R(I)-K4 comparison being piloted by the INER. The laboratories that took part in the comparison were the ARPANSA, the Centre of Technology of Radiation Safety and Metrology (PTKMR-BATAN), Indonesia, the Division of Radiation and Medical Devices (DMSC), Thailand, the INER, the National Centre for Radiation Science (NCRS), New Zealand, the National Institute for Standards (NIS), Egypt and the National Metrology Institute of Japan (NMIJ/AIST), Japan. The two primary laboratories, ARPANSA and NMIJ, were chosen as the linking laboratories. Three ionization chambers were used as transfer instruments to be calibrated in terms of air kerma in 60Co radiotherapy beams. The comparison result is based on the ratio between the air kerma calibration coefficients (NK) determined by the participants and the mean of the results of the linking laboratories. The mean comparison ratio was found to be within 0.5 % of the key comparison reference value KCRV. The largest deviation between any two comparison ratios for the three chambers in terms of air kerma was 2.0 %. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE) in terms of the deviations of the results and their associated uncertainties. As a result of this APMP comparison, the BIPM key comparison database (KCDB) should

  6. MO-D-BRD-04: NIST Air-Kerma Standard for Electronic Brachytherapy Calibrations

    Energy Technology Data Exchange (ETDEWEB)

    Mitch, M. [Nat’l Institute of Standards & Technology (United States)

    2015-06-15

    Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014, a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic

  7. 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)

  8. Re-evaluation of the product of (W/e)air and the graphite to air stopping-power ratio for 60Co air kerma standards.

    Science.gov (United States)

    Thomson, R M; Rogers, D W O

    2010-07-07

    Experiments which determine the product of (W/e)air, the average energy deposited per coulomb of charge of one sign released by an electron coming to rest in dry air, and (LDelta/rho)Ca, the Spencer-Attix mean restricted mass collision stopping-power ratio for graphite to air, in a 60Co or 137Cs beam are reanalysed. Correction factors, e.g., to account for gaps about a calorimeter core or perturbations due to a cavity's presence, are calculated using the EGSnrc Monte Carlo code system and these generally decrease the value of (W/e)air(LDelta/rho)Ca for each experiment. Stopping-power ratios are calculated for different choices of density correction and average excitation energy (I-value) for graphite. To calculate an average value (W/e)air(LBIPM/rho)Ca for the BIPM air kerma standard, each experimental result is multiplied by the ratio (LBIPM/rho)Ca/(LDelta/Rho)Ca. While individual values of (LDelta/rho)Ca are sensitive to the I-values and density corrections assumed, this ratio varies by less than 0.1% for different choices. Hence, the product (W/e)air(LBIPM/rho)Ca is relatively insensitive to these choices. The weighted mean of the updated data is (W/e)air(LBIPM/rho)Ca=33.68 J C(-1)+/-0.2%, suggesting that the accepted value of 33.97 J C(-1)+/-0.1% is 0.8% too high. This has implications for primary 60Co air kerma standards worldwide and potentially for the choice of graphite I-value and density correction for the calculation of the graphite stopping power, as well as the value of (W/e)air.

  9. 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...

  10. 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

  11. 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

  12. 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

  13. 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

  14. European inter-comparison of Monte Carlo codes users for the uncertainty calculation of the kerma in air beside a caesium-137 source; Intercomparaison europeenne d'utilisateurs de codes monte carlo pour le calcul d'incertitudes sur le kerma dans l'air aupres d'une source de cesium-137

    Energy Technology Data Exchange (ETDEWEB)

    De Carlan, L.; Bordy, J.M.; Gouriou, J. [CEA Saclay, LIST, Laboratoire National Henri Becquerel, Laboratoire de Metrologie de la Dose 91 - Gif-sur-Yvette (France)

    2010-07-01

    Within the frame of the CONRAD European project (Coordination Network for Radiation Dosimetry), and more precisely within a work group paying attention to uncertainty assessment in computational dosimetry and aiming at comparing different approaches, the authors report the simulation of an irradiator containing a caesium 137 source to calculate the kerma in air as well as its uncertainty due to different parameters. They present the problem geometry, recall the studied issues (kerma uncertainty, influence of capsule source, influence of the collimator, influence of the air volume surrounding the source). They indicate the codes which have been used (MNCP, Fluka, Penelope, etc.) and discuss the obtained results for the first issue

  15. Key comparison BIPM.RI(I)-K5 of the air kerma standards of the NIM, China, and the BIPM in 137Cs gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Li, D.; Wang, P.

    2015-01-01

    A direct comparison of the standards for air kerma of the National Institute of Metrology (NIM), Beijing, China, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in September 2014. The comparison result, evaluated as a ratio of the NIM and the BIPM standards for air kerma, is 0.9967 with a combined standard uncertainty of 2.1 × 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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Burns, D.T.; Roger, P. [Bureau International des Poids et Mesures, Pavillon de Breteuil, 92312 Sevres CEDEX (France); Knyziak, A.B. [Bureau International des Poids et Mesures, Pavillon de Breteuil, 92312 Sevres CEDEX (France); Glowny Urzad Miar, ul. Elektoralna 2, 00-139 Warsaw (Poland)

    2012-02-15

    A key comparison has been made between the air-kerma standards of the GUM and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement to better than the expanded uncertainty (k = 2) for the comparison of 6.0 parts in 10{sup 3}. 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 NRC, Canada and the BIPM in low-energy x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Burns, D.T.; Kessler, C. [Bureau International des Poids et Mesures (BIPM), Pavillon de Breteuil, F-92312 - Sevres cedex (France); McCaffrey, J.P. [National Research Council, 1200 Montreal Road, Ottawa, (Canada)

    2011-02-15

    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 10{sup 3}. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  18. Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the NRC, Canada and the BIPM in mammography x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), Pavillon de Breteuil, F-92312 Sevres cedex, (France); McCaffrey, J.P. [National Research Council, 1200 Montreal Road, Ottawa, (Canada)

    2011-07-01

    A first key comparison has been made between the air-kerma standards of the NRC and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the combined standard uncertainty of 3.0 parts in 10{sup 3}. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. (authors)

  19. A study of the relationship between peak skin dose and cumulative air kerma in interventional neuroradiology and cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Neil, S; Padgham, C; Martin, C J [Health Physics, Gartnavel Royal Hospital, Glasgow G12 0XH (United Kingdom)

    2010-12-01

    A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3 Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose-area product (DAP) for particular types of procedure, and DAPs of 200-300 Gy cm{sup 2} could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

  20. Summary of the BIPM.RI(I)-K5 comparison for air kerma in 137Cs gamma radiation

    Science.gov (United States)

    Allisy-Roberts, P. J.; Kessler, C.; Burns, D. T.

    2013-01-01

    International comparisons of air kerma in 137Cs gamma radiation beams have been made at the Bureau International des Poids et Mesures (BIPM) since 1994. Twelve national metrology institutes have taken part, seven of which have repeated the comparison over the intervening years. The key comparison reference value (KCRV) is taken as the BIPM evaluation, each comparison result being the ratio of the national metrology institute (NMI) evaluation to that of the BIPM standard under the same reference conditions. The degrees of equivalence between each NMI and the KCRV and a graphical presentation are given using the most recent published result for eleven NMIs. 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).

  1. Accuracy of Spencer-Attix cavity theory and calculations of fluence correction factors for the air kerma formalism.

    Science.gov (United States)

    La Russa, D J; Rogers, D W O

    2009-09-01

    EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for 60Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (K(fl)) by the presence of the cavity. The need for K(fl) corrections arises from the fact that the standard prescription for choosing the low-energy threshold delta in the SA restricted stopping-power ratio consistently underestimates the values of delta needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing delta, but it is not clear how delta can be calculated from first principles. Values of delta required to avoid K(fl) corrections were found to be consistently higher than delta values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of K(fl) have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%.

  2. Calibration of a 7.6 cm x 7.6 cm (3 inch x 3 inch) Sodium Iodide Gamma Ray Spectrometer for Air Kerma Rate

    Energy Technology Data Exchange (ETDEWEB)

    Grasty, R.L.; Walters, B.R.B.; Hovgaard, J.; LaMarre, J.R

    2001-07-01

    An experimental procedure is described for converting a gamma ray spectral measurement from a 7.6 cm x 7.6 cm (3 inch x 3 inch) sodium iodide (NaI) detector to air kerma rate. The calibration procedure involves measuring the energy deposited in the detector using 10 radioactive sources of known activity covering an energy range from 60 keV to 1836 keV. For each of the 10 sources, gamma ray spectra were measured with the source at different angles to the detector axis. The total energy deposited in the detector for the ten sources was confirmed by Monte Carlo calculations. The spectra measured at different angles were combined to produce a spectrum that would represent a homogeneous semi-infinite source of radiation. The resultant spectrum was then subdivided into 10 energy regions. Based on the known air kerma rates due to the sources, a calibration coefficient was calculated for each of the 10 energy regions. These calibration coefficients could then be used to convert the energy deposited in the 10 regions of an unknown spectrum to air kerma rate. The calibration procedure was confirmed by comparing the results from the detector with those from calibrated collimated beams of {sup 137}Cs and {sup 60}Co. A comparison of measurements using a calibrated pressurised ionisation chamber with those from a similar NaI spectrometer in Finland provided additional confirmation of the calibration procedure. (author)

  3. Calculation of conversion coefficients for air kerma to ambient dose equivalent using transmitted spectra of megavoltage X-rays through concrete.

    Science.gov (United States)

    Cordeiro, T P V; Silva, A X

    2012-12-01

    With the fast advancement of technology, (60)Co teletherapy units are largely being replaced with medical linear accelerators. In most cases, the linear accelerator tends to be installed in the same room in which the (60)Co teletherapy unit was previously placed. If in-depth structural remodelling is out of the question, high-density concrete is usually used to improve shielding against primary, scatter and leakage radiation originating in the new equipment. This work presents a study based on Monte Carlo simulations of the transmission of some clinical photon spectra (from 6, 10, 15, 18 and 25 MV accelerators) through concrete, considering two different densities. Concrete walls with thickness ranging from 0.70 to 2.0 m were irradiated with 30 cm×30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to ∼65 % when barite (high-density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. In addition, conversion coefficients from air kerma to ambient dose equivalent, H*(d)/K(air), and air kerma to effective dose, E/K(air), for photon spectra from the transmitted spectra were calculated and compared. The results suggest that the 10-mm depth is not the best choice to represent the effective dose.

  4. 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...

  5. 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

  6. 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)

  7. 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)

  8. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the LNE-LNHB, France and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Delaunay, F.; Donois, M.

    2013-01-01

    An indirect comparison of the standards for air kerma of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in April 2013. The comparison result, evaluated as a ratio of the LNE-LNHB and the BIPM standards for air kerma, is 0.9994 with a combined standard uncertainty of 1.8 × 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).

  9. KEY COMPARISON: Comparison of the standards for air kerma of the LNE-LNHB and the BIPM for 137Cs gamma radiation

    Science.gov (United States)

    Allisy-Roberts, P. J.; Kessler, C.; Burns, D. T.; Delaunay, F.; Donois, M.

    2009-01-01

    A direct comparison of the standards for air kerma of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in November 2008. The result, expressed as a ratio of the LNE-LNHB and the BIPM standards for air kerma, is 0.9984 with a combined standard uncertainty of 2.6 × 10-3. The result of the earlier direct comparison in 137Cs γ rays, made in 1995, was 1.0019(30); taking into account the changes made to the BIPM standard and using the present correction factors for the LNE-LNHB standard, the 1995 result becomes 0.9989(26), which is in agreement with the present comparison result. 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).

  10. Evaluation of wall correction factor of INER's air-kerma primary standard chamber and dose variation by source displacement for HDR ¹⁹²Ir brachytherapy.

    Science.gov (United States)

    Lee, J H; Wang, J N; Huang, T T; Su, S H; Chang, B J; Su, C H; Hsu, S M

    2013-01-01

    The aim of the present study was to estimate the wall effect of the self-made spherical graphite-walled cavity chamber with the Monte Carlo method for establishing the air-kerma primary standard of high-dose-rate (HDR) ¹⁹²Ir brachytherapy sources at the Institute of Nuclear Energy Research (INER, Taiwan). The Monte Carlo method established in this paper was also employed to respectively simulate wall correction factors of the ¹⁹²Ir air-kerma standard chambers used at the National Institute of Standards and Technology (NIST, USA) and the National Physical Laboratory (NPL, UK) for comparisons and verification. The chamber wall correction calculation results will be incorporated into INER's HDR ¹⁹²Ir primary standard in the future. For the brachytherapy treatment in the esophagus or in the bronchi, the position of the isotope may have displacement in the cavity. Thus the delivered dose would differ from the prescribed dose in the treatment plan. We also tried assessing dose distribution due to the position displacement of HDR ¹⁹²Ir brachytherapy source in a phantom with a central cavity by the Monte Carlo method. The calculated results could offer a clinical reference for the brachytherapy within the human organs with cavity.

  11. 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.

    Science.gov (United States)

    Dong, S L; Chu, T C; Lee, J S; Lan, G Y; Wu, T H; Yeh, Y H; Hwang, J J

    2002-12-01

    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.

  12. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the SCK.CEN, Belgium and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D.; Mihailescu, L. C.; Chiriotti, S.

    2017-01-01

    A first key comparison of the standards for air kerma of the Laboratory for Nuclear Calibrations (LNK) from the Studiecentrum voor Kernenergie—Centre d'Etude de l'Energie Nucleaire (SCK.CEN), Belgium and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in September 2016. The comparison result, evaluated as a ratio of the SCK.CEN and the BIPM standards for air kerma, is 1.0021 with a combined standard uncertainty of 2.6 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 7 parts in 104. 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).

  13. Investigation of photon spectra and contributions to air kerma rates in the environment near nuclear facilities using portable germanium gamma spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.J. [Centre for Environment, Fisheries and Aquaculture Science, Lowestoft (United Kingdom)

    2000-05-01

    Portable spectrometers based on NaI or Ge detectors are now important additions to the tools available for monitoring and assessment of radioactivity and radiation dose rates in the environment due to both natural and anthropogenic sources. The high resolution of the Ge detector is of particular use in rapidly identifying and assessing radionuclides of significance. Portable spectrometry is of importance in assessing deposited activity and contributions to air kerma rates, and the rapid availability of these results would be significant in the event of a nuclear emergency in addition to the more usual application of measuring concentrations of radionuclides in environmental samples. In the course of developing a portable germanium detector system, spectra were measured at a number of locations in the environment near nuclear establishments in the UK. These spectra are presented and analysed in this paper in terms of the radionuclide contributions and gamma air kerma rates. Particular features are highlighted. First, background contributions are characterised using an example spectrum measured at Lowestoft beach, where anthropogenic influences are low. By contrast, near the Magnox nuclear power station at Bradwell, Essex there are contributions to the spectra due to photons from {sup 16}N, {sup 41}Ar and {sup 60}Co. In the Ravenglass estuary near Sellafield, {sup 137}Cs features prominently, with smaller contributions due to other radionuclides discharged in liquid waste from Sellafield. In the Ribble estuary which is influenced by discharges from the Springfields fuel fabrication plant as well as from Sellafield, measurements were made on a houseboat at high and low tide; there was a significant difference in the contribution due to {sup 137}Cs from Sellafield. Upstream of the Springfields works, peaks in the spectrum were observed due to {sup 234}Th and {sup 234m}Pa due to discharges from the site, as well as {sup 137}Cs from BNFL Sellafield. The paper highlights

  14. Interlaboratory comparisons in kerma in the air measures and absorbed dose in water using {sup 6}0Co beams in radiotherapy; Comparacoes interlaboratoriais nas medidas de kerma no ar e dose absorvida na agua utilizando feixes de {sup 60}Co em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves; Silva, Cosme Norival Mello da, E-mail: phrosado@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    In order to ensure that the measures of a quantity have high reliability and traceability interlaboratory comparisons are performed. The LNMRI has participated in several these interlaboratory comparisons. In the period 2000-2013 the LNMRI participated in 5 interlaboratory comparisons for measurement of kerma coefficients in the air and absorbed dose coefficients in the water. The results of interlaboratory comparisons indicate that the measures taken are appropriate to the LNMRI regarding the accuracy and precision measuring of these quantities.

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

    Science.gov (United States)

    Batista, Wilson Otto; Soares, Maria Rosangela; de Oliveira, Marcus V L; Maia, Ana F; Caldas, Linda V E

    2015-06-01

    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 (14cm×8.5cm-maxilla/mandible) and protocol [GX2] symmetrical beam (8.5cm×8.5cm-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]: 44.5µSv/478mGycm(2); [GX2]: 54.8µSv/507mGycm(2). Although the ratio of the diameters (14cm/8.5cm)=1.65, the ratio of effective dose values (44.5µSv/54.8µSv)=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.

  16. 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)

  17. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    Energy Technology Data Exchange (ETDEWEB)

    Crosbie, Jeffrey C.; Rogers, Peter A. W. [Department of Obstetrics and Gynaecology, University of Melbourne, The Royal Women' s Hospital, Parkville, Victoria 3052 (Australia); Stevenson, Andrew W. [CSIRO Materials Science and Engineering, Clayton, Victoria 3169 (Australia); Hall, Christopher J. [Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168 (Australia); Lye, Jessica E. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085 (Australia); Nordstroem, Terese [KTH Royal Institute of Technology, Stockholm SE-100 44 (Sweden); Midgley, Stewart M. [School of Physics, Monash University, Clayton, Victoria 3800 (Australia); Lewis, Robert A. [Department of Medical Imaging and Radiation Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation

  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

    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.

  19. 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

  20. Air kerma to HP(3) conversion coefficients for photons from 10 keV to 10 MeV, calculated in a cylindrical phantom.

    Science.gov (United States)

    Gualdrini, G; Bordy, J M; Daures, J; Fantuzzi, E; Ferrari, P; Mariotti, F; Vanhavere, F

    2013-05-01

    In the framework of the ORAMED project (Optimization of RAdiation protection for MEDical staff), funded by the European Union Seventh Framework Programme, different studies were aimed at improving the quality of radiation protection in interventional radiology and nuclear medicine. The main results of the project were presented during a final workshop held in Barcelona in January 2011, the proceedings of which are available in the open literature. One of the ORAMED tasks was focused on the problem of eye-lens photon exposure of the medical staff, a topic that gained more importance especially after the ICRP decision to lower the limiting equivalent dose to 20 mSv per year. The present technical note has the scope, besides briefly summarising the physical reasons of the proposal and the practical implications, to provide, in tabular form, a set of air kerma to Hp(3) conversion coefficients based on the adoption of a theoretical cylindrical model that is well suited for reproduction of the mass and the shape of a human head.

  1. Comparison of air kerma standards of LNE-LNHB and NPL for 192Ir HDR brachytherapy sources: EUROMET project no 814.

    Science.gov (United States)

    Douysset, Guilhem; Sander, Thorsten; Gouriou, Jean; Nutbrown, Rebecca

    2008-03-21

    An indirect comparison has been made in the air kerma standards for high dose rate (HDR) 192Ir brachytherapy sources at the Laboratoire National Henri Becquerel (LNHB) and the National Physical Laboratory (NPL). The measurements were carried out at both laboratories between November and December 2004. The comparison was based on measurements using well-type transfer ionization chambers and two different source types, Nucletron microSelectron HDR Classic and version 2. The results show the reported calibration coefficients to agree within 0.47% to 0.63%, which is within the overall standard uncertainty of 0.65% reported by both laboratories at the time of this comparison. Following this comparison, some of the NPL primary standard correction factors were re-evaluated resulting in a change of +0.17% in the overall correction factor. The new factor was implemented in May 2006. Applying the revised chamber factor to the measurements reported in this comparison report will reduce the difference between the two standards by 0.17%.

  2. Comparison of air kerma measurements between the PTB and the IAEA for x-radiation qualities used in general diagnostic radiology and mammography

    Science.gov (United States)

    Csete, István; Büermann, Ludwig; Gomola, Igor; Girzikowsky, Reinhard

    2013-01-01

    A comparison of the air kerma standards for x-radiation qualities used in general diagnostic radiology and mammography, identified as EURAMET.RI(I)-S10 (EURAMET project #1221), was performed between the PTB and the IAEA. Two spherical and two parallel-plate reference-class ionization chambers of the IAEA and 12 beam qualities standardized in the IEC standard 61267:2005 plus 7 additional standard beam qualities established at both laboratories were selected for the comparison. The calibration coefficients were determined for the transfer chambers at the PTB in September 2012 and before and after this at the IAEA Dosimetry Laboratory. The results show the calibration coefficients of both laboratories to be in good agreement within the standard uncertainty of the comparison of about 0.47%. 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 EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. 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.

    Science.gov (United States)

    Perichon, N; Rapp, B; Denoziere, M; Daures, J; Ostrowsky, A; Bordy, J-M

    2013-05-07

    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.

  4. 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

  5. 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

  6. 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)

  7. 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.

  8. Report on EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 (EUROMET project no. 813): Comparison of air kerma and absorbed dose to water measurements of {sup 60}Co radiation beams for radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Csete, I. [National Office of Measures (OMH) - pilot laboratory and corresponding author (Hungary); Leiton, A.G. [Research Centre for Energy, Environment and Technology (CMRI-CIEMAT) (Spain); Sochor, V. [Czech Metrology Institute (CMI) (Czech Republic); Lapenas, A. [Latvian National Metrology Center (LNMC-RMTC) (Latvia); Grindborg, J.E. [Swedish Radiation Protection Authority (SSI) (Sweden); Jokelainen, I. [Radiation and Nuclear Safety Authority (STUK) (Finland); Bjerke, H. [Norwegian Radiation Protection Authority (NRPA) (Norway); Dobrovodsky, J. [Slovak Institute of Metrology (SMU) (Slovakia); Megzifene, A. [International Atomic Energy Agency, IAEA, Vienna (Austria); Hourdakis, C.J. [Hellenic Atomic Energy Committee (HAEC-HIRCL) (Greece); Ivanov, R. [National Centre of Metrology (NCM) (Bulgaria); Vekic, B. [Rudjer Boskovic Institute (IRB) (Croatia); Kokocinski, J. [Central Office of Measures (GUM) (Poland); Cardoso, J. [Institute for Nuclear Technology (ITN-LMRIR) (Portugal); Buermann, L. [Physikalisch Technische Bundesanstalt (PTB) (Germany); Tiefenboeck, W. [Bundesamt fur Eich und Vermesungswesen (BEV) (Austria); Stucki, G. [17 Bundesamt fur Metrologie (METAS) (Switzerland); Van Dijk, E. [NMi Van Swinden Laboratorium (NMi) (Netherlands); Toni, M.P. [ENEA-CR Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (ENEA) (Italy); Minniti, R. [20 National Institute of Standards and Technology (NIST) (United States); McCaffrey, J.P. [National Research Council Canada (NRC) (Canada); Silva, C.N.M. [National Metrology Laboratory of Ionizing Radiation (LNMRI-IRD) (Brazil); Kharitonov, I. [D I Mendeleyev Institute for Metrology (VNIIM) (RU); Webb, D. [Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) (Australia); Saravi, M. [National Atomic Energy Commission (CNEA-CAE) (Argentina); Delaunay, F. [Laboratoire National Henri Becquerel (LNE-LNHB) (France)

    2010-06-15

    The results of an unprecedented international effort involving 26 countries are reported. The EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 key comparisons were conducted with the goal of supporting the relevant calibration and measurement capabilities (CMC) planned for publication by the participant laboratories. The measured quantities were the air kerma (K{sub air}) and the absorbed dose to water (Dw) in {sup 60}Co radiotherapy beams. The comparison was conducted by the pilot laboratory MKEH (Hungary), in a star-shaped arrangement from January 2005 to December 2008. The calibration coefficients of four transfer ionization chambers were measured using two electrometers. The largest deviation between any two calibration coefficients for the four chambers in terms of air kerma and absorbed dose to water was 2.7% and 3.3% respectively. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE), in terms of the deviations of the results and their associated uncertainties. As a result of this EUROMET project 813 comparison, the BIPM key comparison database (KCDB) will include eleven new Kair and fourteen new D{sub w} DoE values of European secondary standard dosimetry laboratories (SSDLs), and the KCDB will be updated with the new DoE values of the other participant laboratories. The pair-wise degrees of equivalence of participants were also calculated. In addition to assessing calibration techniques and uncertainty calculations of the participants, these comparisons enabled the experimental determinations of N{sub Dw}/N{sub Kair} ratios in the {sup 60}Co gamma radiation beam for the four radiotherapy transfer chambers. (authors)

  9. AIR KERMA TO Hp(3) CONVERSION COEFFICIENTS FOR IEC 61267 RQR X-RAY RADIATION QUALITIES: APPLICATION TO DOSE MONITORING OF THE LENS OF THE EYE IN MEDICAL DIAGNOSTICS.

    Science.gov (United States)

    Principi, S; Guardiola, C; Duch, M A; Ginjaume, M

    2016-09-01

    Recent studies highlight the fact that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens monitoring could be required for these workers. The recommended operational quantity for monitoring of eye lens exposure is the personal dose equivalent at 3 mm depth Hp(3) (ICRU 51). However, there are no available conversion coefficients in international standards, while in the literature coefficients have only been calculated for monoenergetic beams and for ISO 4037-1 X-ray qualities. The aim of this article is to provide air kerma to Hp(3) conversion coefficients for a cylindrical phantom made of ICRU-4 elements tissue-equivalent material for RQR radiation qualities (IEC-61267) from 40 to 120 kV and for angles of incidence from 0 to 180°, which are characteristic of medical workplace. Analytic calculations using interpolation techniques and Monte Carlo modelling have been compared.

  10. Evaluation of kerma rate in radioactive waste disposal; Avaliacao da taxa de kerma em deposito de rejeitos radioativos

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, Rodolfo O.; Silva, Joao C.P.; Santos, Joao R. dos, E-mail: oliveira@ien.gov.br, E-mail: jcarlos@ien.gov.br, E-mail: regis@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This study aims to assess the progression of kerma rate levels in the air due to the increase of collection, storing and storage of radioactive waste in the new building (after expansion) of the radioactive waste disposal (RWD) of the Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Brazil. This review is carried out every six months at IEN with thermoluminescent dosimeter lithium fluoride LiF: Mg, Cu, P (TLD-100H). Here are the average values of kerma rate for the period 2008- 2012. In this context, the methodology used for selection and choices of detectors used in dosimeters is presented. The detectors were chosen through homogeneity criteria of the pack, standardization factor and coefficient of variation (CV%). The monitoring points and the exposure time of the detectors are chosen considering various factors, including the rate of occupation and indoor and outdoor positions to RWD. These evaluations showed that the contribution of the new waste disposal in increasing kerma rate of IEN, has proved to be insignificant, that is, the presence of RWD does not contribute to increased environmental kerma rate in the region around this installation.

  11. Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms.

    Science.gov (United States)

    Maehata, Itsumi; Hayashi, Hiroaki; Kimoto, Natsumi; Takegami, Kazuki; Okino, Hiroki; Kanazawa, Yuki; Tominaga, Masahide

    2016-07-01

    We propose a new practical method for the construction of an accurate secondary X-ray field using medical diagnostic X-ray equipment. For accurate measurement of the air kerma of an X-ray field, it is important to reduce and evaluate the contamination rate of scattered X-rays. To determine the rate quantitatively, we performed the following studies. First, we developed a shield box in which an ionization chamber could be set at an inner of the box to prevent detection of the X-rays scattered from the air. In addition, we made collimator plates which were placed near the X-ray source for estimation of the contamination rate by scattered X-rays from the movable diaphragm which is a component of the X-ray equipment. Then, we measured the exposure dose while changing the collimator plates, which had diameters of 25-90 mm(ϕ). The ideal value of the exposure dose was derived mathematically by extrapolation to 0 mm(ϕ). Tube voltages ranged from 40 to 130 kV. Under these irradiation conditions, we analyzed the contamination rate by the scattered X-rays. We found that the contamination rates were less than 1.7 and 2.3 %, caused by air and the movable diaphragm, respectively. The extrapolated value of the exposure dose has been determined to have an uncertainty of 0.7 %. The ionization chamber used in this study was calibrated with an accuracy of 5 %. Using this kind of ionization chamber, we can construct a secondary X-ray field with an uncertainty of 5 %.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. 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)

  17. Monte CarIo SimuIation of PhysicaI Parameters for Air Kerma Measurement by Graphite Pancake Ionization Chamber%圆饼电离室空气比释动能物理参量的蒙特卡洛模拟

    Institute of Scientific and Technical Information of China (English)

    王坤; 李涛; 金孙均; 杨小元; 樊铁栓

    2016-01-01

    为建立基于圆饼电离室系统的60 Coγ射线空气比释动能基准装置,对辐射场及场中电离室的相关物理参量进行了蒙特卡洛模拟研究。通过BEAMnrc程序建立辐照器模型计算测量点处能谱和注量分布,使用EGSnrc计算圆饼电离室在辐射场中各物理参量。60 Coγ射线空气比释动能绝对测量装置通过蒙特卡洛模拟得到的相关物理参数合成不确定度为0.20豫,该结果与澳大利亚计量院同结构电离室的结果在不确定度范围内一致,与国家基准球-圆柱形电离室及球形电离室相比在不确定范围内符合。%In order to establish the air kerma primary standard based on a graphite pancake ionization chamber for 60 Co gamma rays,the radiation field and related physical parameters of the chamber are calculated by the Monte Carlo simulation method. The γ-ray energy spectra and fluence distributions are calculated by the model built by BEAMnrc code,the parameters of the graphite pancake ionization chamber in 60 Co γ-ray radiation filed are calculated by EGSnrc code. The combined standard uncertainty of the parameters of the chamber calculated by Monte Carlo method is 0. 20%,the results of simulation are accord with results of the same structural chamber from the ARPANSA in the region of the uncertainty. And the change of the values with the primary standard based on a sphere-cylindrical graphite ionization chamber is under expected.

  18. 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)

  19. 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

  20. Electric field strength of charged conducting balls and the breakdown of the air gap between them

    Energy Technology Data Exchange (ETDEWEB)

    Saranin, Vladimir A [Department of Physics, V.G. Korolenko Glazov State Pedagogical Institute, Glazov (Russian Federation)

    2002-12-31

    Field amplification factors at the surfaces of two charged conducting balls are calculated numerically. It is shown that as the balls are brought closer together, except when their potentials are equal, the amplification factors go to infinity, and in the case of like-charged balls the field at the surface of one of them changes sign. Breakdown field strengths for the air gap between balls of a different diameter are calculated using the experimental data of other authors as the base. The results suggest that the minimum breakdown field strength is 26 kV cm{sup -1} . The author's earlier results on the interaction force between the balls are revised. (methodological notes)

  1. Influence of warm air-drying on enamel bond strength and surface free-energy of self-etch adhesives.

    Science.gov (United States)

    Shiratsuchi, Koji; Tsujimoto, Akimasa; Takamizawa, Toshiki; Furuichi, Tetsuya; Tsubota, Keishi; Kurokawa, Hiroyasu; Miyazaki, Masashi

    2013-08-01

    We examined the effect of warm air-drying on the enamel bond strengths and the surface free-energy of three single-step self-etch adhesives. Bovine mandibular incisors were mounted in self-curing resin and then wet ground with #600 silicon carbide (SiC) paper. The adhesives were applied according to the instructions of the respective manufacturers and then dried in a stream of normal (23°C) or warm (37°C) air for 5, 10, and 20 s. After visible-light irradiation of the adhesives, resin composites were condensed into a mold and polymerized. Ten samples per test group were stored in distilled water at 37°C for 24 h and then the bond strengths were measured. The surface free-energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths varied according to the air-drying time and ranged from 15.8 to 19.1 MPa. The trends for the bond strengths were different among the materials. The value of the γS⁺ component increased slightly when drying was performed with a stream of warm air, whereas that of the γS⁻ component decreased significantly. These data suggest that warm air-drying is essential to obtain adequate enamel bond strengths, although increasing the drying time did not significantly influence the bond strength.

  2. 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.

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

    Science.gov (United States)

    Eshghi, Alireza; Khoroushi, Maryam; Rezvani, Alireza

    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 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. Results: 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. Conclusion: 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. PMID:25628694

  4. 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.

  5. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    Science.gov (United States)

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R

    1997-11-01

    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that enamel surface preparation using air-abrasion results in a significant lower

  6. Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

    Science.gov (United States)

    Singh, Vishwanath P.; Badiger, N. M.

    2014-11-01

    Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

  7. KERMA-based radiation dose management system for real-time patient dose measurement

    Science.gov (United States)

    Kim, Kyo-Tae; Heo, Ye-Ji; Oh, Kyung-Min; Nam, Sang-Hee; Kang, Sang-Sik; Park, Ji-Koon; Song, Yong-Keun; Park, Sung-Kwang

    2016-07-01

    Because systems that reduce radiation exposure during diagnostic procedures must be developed, significant time and financial resources have been invested in constructing radiation dose management systems. In the present study, the characteristics of an existing ionization-based system were compared to those of a system based on the kinetic energy released per unit mass (KERMA). Furthermore, the feasibility of using the KERMA-based system for patient radiation dose management was verified. The ionization-based system corrected the effects resulting from radiation parameter perturbations in general radiography whereas the KERMA-based system did not. Because of this difference, the KERMA-based radiation dose management system might overestimate the patient's radiation dose due to changes in the radiation conditions. Therefore, if a correction factor describing the correlation between the systems is applied to resolve this issue, then a radiation dose management system can be developed that will enable real-time measurement of the patient's radiation exposure and acquisition of diagnostic images.

  8. 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.

  9. Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

    Science.gov (United States)

    Zhang, Chunming; Zhao, Meihua; Wang, Libing; Qu, Lijun; Men, Yajing

    2017-04-01

    Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(Cdbnd O, Csbnd OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

  10. 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.

  11. Building Combat Strength through Logistics: Translating the New Air Force Logistics Concept of Operations into Action

    Science.gov (United States)

    1988-03-31

    Monica, California, in May 87 to define an Air Force game plan for implementing CLOUT. (11:9-15) This effort was later superceded by the AFLOGCON...LOGISTS - - P/60 SYSTEM ADtMINLOGISflCS /Go.. READINESS I ADAM III If CENTER L ---- - - - -. THEATER MOBa Name, WTrU SBSS RE7TAIL WrA"i,0 SATELLITE USERS

  12. 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 MDP/4-META) were superior to other compositions.

  13. Strength Testing in the Air Force: Current Processes and Suggestions for Improvements

    Science.gov (United States)

    2014-01-01

    rack to put it on the shelf. While scrubbed into surgical procedures surgical techs (SS) frequently aid the surgeon by holding retractors. The...Forces SME subject matter expert SS Surgical Service - 1 - 1. Introduction The Strength Aptitude Test (SAT) is used to screen and classify...2A6X4 60 128 1,893 Cyber Surety (CS) 3D0X3 40 299 1,175 Surgical Service (SS) 4N1X1 40 354 705 NOTE: See Appendix F for population

  14. A consistent set of neutron kerma coefficients from thermal to 150 MeV for biologically important materials

    Energy Technology Data Exchange (ETDEWEB)

    Chadwick, M.B. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barschall, H.H. [Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53706-1532 (United States); Caswell, R.S. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); DeLuca, P.M. [Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53706-1532 (United States); Hale, G.M. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Jones, D.T. [National Accelerator Centre, Faure, CapeTown (South Africa); MacFarlane, R.E. [University of California, Los Alamos, National Laboratory, Los Alamos, New Mexico 87545 (United States); Meulders, J.P. [Universite Catholique de Louvain, Louvain-la-Neuve (Belgium); Schuhmacher, H.; Schrewe, U.J. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Wambersie, A. [Universite Catholique de Louvain, Louvain-la-Neuve (Belgium); Young, P.G. [University of California, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-06-01

    Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determine kerma coefficients for calculations of energy deposition by neutrons in matter. Methods used to evaluate the neutron cross sections above 20 MeV, using nuclear model calculations and experimental data, are described. Below 20 MeV, the evaluated cross sections from the ENDF/B-VI library are adopted. Comparisons are shown between the evaluated charged-particle production cross sections and measured data. Kerma coefficients are derived from the neutron cross sections, for major isotopes of H, C, N, O, Al, Si, P, Ca, Fe, Cu, W, Pb, and for ICRU-muscle, A-150 tissue-equivalent plastic, and other compounds important for treatment planning and dosimetry. Numerous comparisons are made between our kerma coefficients and experimental kerma coefficient data, to validate our results, and agreement is found to be good. An important quantity in neutron dosimetry is the kerma coefficient ratio of ICRU-muscle to A-150 plastic. When this ratio is calculated from our kerma coefficient data, and averaged over the neutron energy spectra for higher-energy clinical therapy beams [three p(68)+Be beams, and a d(48.5)+Be beam], a value of 0.94{plus_minus}0.03 is obtained. Kerma ratios for water to A-150 plastic, and carbon to oxygen, are also compared with measurements where available. {copyright} {ital 1999 American Association of Physicists in Medicine.}

  15. Comparison between calibration methods of kerma-area product (P{sub KA}); Comparacao entre metodos de calibracao do produto kerma-area (P{sub KA})

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, V.C.C.; Macedo, E.M.; Pereira, L.C.S.; Modesto, I.F.; Ferreira, M.; Navarro, M.V.T., E-mail: valeria@ifba.edu.br [Instituto Federal da Bahia (LABPROSAUD/IFBA), Salvador, BA (Brazil). Laboratorio de Produtos para a Saude

    2015-07-01

    P{sub KA} is a relevant dosimetric quantity utilized mainly in interventional radiology procedures, and it's calibration essential for maintenance of the metrological reliability in measurements. As there are two methods to calibrate this kind of meters (substitution method and directly measuring kerma and area), the goal of this study was to compare them, in order to indicate which is the better option to be implanted at Calibration Laboratory Labprosaud/IFBA. The results showed a good equivalence between two methods, with minimal concordance of 99,2% between calibration factors. However, the substitution method ensure higher metrological reliability with uncertainties 60% lower. This method was implanted at Labprosaud. (author)

  16. Comparison of entry kerma in the skin with the variation of automatic exposure control in mammography;Comparacao do kerma de entrada na pele com a variacao do controle automatico de exposicao em exames mamograficos

    Energy Technology Data Exchange (ETDEWEB)

    Macao Junior, J.L. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Mecca, F.A. [Instituto Nacional de Cancer (INCa), Rio de Janeiro, RJ (Brazil); Gomes, B.C. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The purpose of this work was to analyze the entry kerma values in the skin in comparison with the automatic exposure control tests. To achieve that, 44 mammographies were evaluatecl in the city of Rio de Janeiro. The reference values adopted were taken from the current Brazilian legislation, 'Portaria no. 453/98 do Ministerio da Saude', where the reference entry kerma value in the skin corresponds to 10 mGy and the maximum variation accepted to the automatic exposure control test corresponds to 30 optic unities. It was observed that 46.7% of the analyzecl mammographies presented entry kerma values in the skin above the reference level established, whereas the automatic exposition control for these same mammographies was within the acceptability parameters. (author)

  17. 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

    The effective atomic number, Z(eff), the effective electron density, N-el, and kerma have been calculated for some fatty acids and carbohydrates for photon interaction in the extended energy range from 1 keV to 100 GeV using an accurate database of photon-interaction cross sections and the Win....... The minimum values of Z(eff) and N-el are found at intermediate energies, typically 0.05 MeV bio-molecule. Wherever possible, the calculations are compared with experimental results. A comparison...

  18. 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.

  19. Electricity generation and nutrients removal from high-strength liquid manure by air-cathode microbial fuel cells.

    Science.gov (United States)

    Lin, Hongjian; Wu, Xiao; Nelson, Chad; Miller, Curtis; Zhu, Jun

    2016-01-01

    Air-cathode microbial fuel cells (MFCs) are widely tested to recover electrical energy from waste streams containing organic matter. When high-strength wastewater, such as liquid animal manure, is used as a medium, inhibition on anode and cathode catalysts potentially impairs the effectiveness of MFC performance in power generation and pollutant removal. This study evaluated possible inhibitive effects of liquid swine manure components on MFC power generation, improved liquid manure-fed MFCs performance by pretreatment (dilution and selective adsorption), and modeled the kinetics of organic matter and nutrients removal kinetics. Parameters monitored included pH, conductivity, chemical oxygen demand (COD), volatile fatty acids (VFAs), total ammoniacal nitrogen (TAN), nitrite, nitrate, and phosphate concentrations. The removals of VFA and TAN were efficient, indicated by the short half-life times of 4.99 and 7.84 d, respectively. The mechanism for phosphate decrease was principally the salt precipitation on cathode, but the removal was incomplete after 42-d operation. MFC with an external resistor of 2.2 kΩ and fed with swine wastewater generated relatively small power (28.2 μW), energy efficiency (0.37%) and Coulombic efficiency (1.5%). Dilution of swine wastewater dramatically improved the power generation as the inhibitory effect was decreased. Zeolite and granular activated carbon were effective in the selective adsorption of ammonia or organic matter in swine wastewater, and so substantially improved the power generation, energy efficiency, and Coulombic efficiency. A smaller external resistor in the circuit was also observed to promote the organic matter degradation and thus to shorten the treatment time. Overall, air-cathode MFCs are promising for generating electrical power from livestock wastewater and meanwhile reducing the level of organic matter and nutrients.

  20. 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

  1. The comparison of cold-water immersion and cold air therapy on maximal cycling performance and recovery markers following strength exercises

    Directory of Open Access Journals (Sweden)

    Kane J. Hayter

    2016-03-01

    Full Text Available This study examined the effects of cold-water immersion (CWI and cold air therapy (CAT on maximal cycling performance (i.e. anaerobic power and markers of muscle damage following a strength training session. Twenty endurance-trained but strength-untrained male (n = 10 and female (n = 10 participants were randomised into either: CWI (15 min in 14 °C water to iliac crest or CAT (15 min in 14 °C air immediately following strength training (i.e. 3 sets of leg press, leg extensions and leg curls at 6 repetition maximum, respectively. Creatine kinase, muscle soreness and fatigue, isometric knee extensor and flexor torque and cycling anaerobic power were measured prior to, immediately after and at 24 (T24, 48 (T48 and 72 (T72 h post-strength exercises. No significant differences were found between treatments for any of the measured variables (p > 0.05. However, trends suggested recovery was greater in CWI than CAT for cycling anaerobic power at T24 (10% ± 2%, ES = 0.90, T48 (8% ± 2%, ES = 0.64 and T72 (8% ± 7%, ES = 0.76. The findings suggest the combination of hydrostatic pressure and cold temperature may be favourable for recovery from strength training rather than cold temperature alone.

  2. Effect of the new ASTM E 722-93 (Si) Kerma displacement data on reactor neutron dosimetry

    Science.gov (United States)

    Morin, J.; Arnoud, J. C.; David, J.; Zyromski, P.

    1998-02-01

    Studies on hardening performed with PROSPERO and CALIBAN reactors require dosimetry in order to measure the 1 MeV (Si) equivalent neutron fluence, either with activation detectors, or with PIN (Si) diodes. Taking into account the latest ASTM E 722-93 (Si) Kerma displacement data enhances the accuracy and consistency of the results.

  3. Effect of the new ASTM E 722-93 (Si) Kerma displacement data on reactor neutron dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Morin, J.; Arnoud, J.C.; David, J.; Zyromski, P. [CEA Centre d`Etudes de Valduc, 21 - Is-sur-Tille (France)

    1998-01-01

    Studies on hardening performed with PROSPERO and CALIBAN reactors require dosimetry in order to measure the 1 MeV (Si) equivalent neutron fluence, either with activation detectors, or with PIN (Si) diodes. Taking into account the latest ASTM E 722-93 (Si) Kerma displacement data enhances the accuracy and consistency of the results. (orig.). 8 refs.

  4. Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes.

    Science.gov (United States)

    Nguyen, D T; McCanless, J D; Mecwan, M M; Noblett, A P; Haggard, W O; Smith, R A; Bumgardner, J D

    2013-01-01

    The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

  5. 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.

  6. Development of Fine-Grained, Low-Carbon Bainitic Steels with High Strength and Toughness Produced Through the Conventional Hot-Rolling and Air-Cooling

    Science.gov (United States)

    Dhua, Sanjay Kumar; Sarkar, Partha Pratim; Saxena, Atul; Jha, Bimal Kumar

    2016-12-01

    Low-carbon bainitic steels have created enormous interest among scientists across the world in the past few decades because of their high strength, toughness, and weldability replacing the conventional quenched and tempered medium-carbon steels. Three experimental steels with varying alloy additions were made in a 100-kg laboratory induction furnace and cast into 100-mm-diameter cylindrical ingots. These ingots were hot-rolled and air-cooled to 6-mm plates in an experimental rolling mill with selected thermomechanical parameters. Steels processed through this process provided an ultrafine low-carbon bainitic microstructure with maximum yield strength (YS) and ultimate tensile strength (UTS) 575 and 705 MPa, respectively. The Charpy impact toughness of the experimental steels was excellent, and at 253 K (-20 °C), it varied from 114 to 170 Joules. Cu-B-added steel was found to give an optimum combination of strength, YS-575 MPa, and toughness, 114 J at 253 K (-20 °C). Thus, fine-grained, low-carbon bainitic steels could be developed with a proper combination of alloying elements and thermomechanical parameters even by air-cooling.

  7. Development of Fine-Grained, Low-Carbon Bainitic Steels with High Strength and Toughness Produced Through the Conventional Hot-Rolling and Air-Cooling

    Science.gov (United States)

    Dhua, Sanjay Kumar; Sarkar, Partha Pratim; Saxena, Atul; Jha, Bimal Kumar

    2016-09-01

    Low-carbon bainitic steels have created enormous interest among scientists across the world in the past few decades because of their high strength, toughness, and weldability replacing the conventional quenched and tempered medium-carbon steels. Three experimental steels with varying alloy additions were made in a 100-kg laboratory induction furnace and cast into 100-mm-diameter cylindrical ingots. These ingots were hot-rolled and air-cooled to 6-mm plates in an experimental rolling mill with selected thermomechanical parameters. Steels processed through this process provided an ultrafine low-carbon bainitic microstructure with maximum yield strength (YS) and ultimate tensile strength (UTS) 575 and 705 MPa, respectively. The Charpy impact toughness of the experimental steels was excellent, and at 253 K (-20 °C), it varied from 114 to 170 Joules. Cu-B-added steel was found to give an optimum combination of strength, YS-575 MPa, and toughness, 114 J at 253 K (-20 °C). Thus, fine-grained, low-carbon bainitic steels could be developed with a proper combination of alloying elements and thermomechanical parameters even by air-cooling.

  8. 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.

  9. Evaluation of the Kerma at the entrance of the labyrin thin in facilities with Co-60 HDR brachytherapy; Evaluacion del Kerma en la entrada del laberinto en instalaciones de braquiterapia de HDR con Co-60

    Energy Technology Data Exchange (ETDEWEB)

    Pujades, M. C.; Granero, D.; Ballester, F.; Perez-Calatayud, J.; Vijande, J.

    2013-07-01

    The purpose of this study is to evaluate the kerma's collision at the entrance of the labyrinth adapting the methodology of the NCRP-151 to a bunker of brachytherapy with Co-60, similar to the one carried out in a previous work with HDR Ir-192. To validate the result is simulated using techniques Monte Carlo (MC) two typical designs of HDR with Co-60 bunker. (Author)

  10. Assessment of the effects of flow rate and ionic strength on the performance of an air-cathode microbial fuel cell using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, D.; Tsouris, C. [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Tsouris, C. [Nuclear Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hamilton, Ch. Y. [The University of Tennessee, Knoxville, TN 37996 (United States); Borole, A. P. [BioSciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2010-07-01

    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. (author)

  11. 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.

  12. 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

  13. 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.

  14. Integrated catalytic wet air oxidation and aerobic biological treatment in a municipal WWTP of a high-strength o-cresol wastewater.

    Science.gov (United States)

    Suarez-Ojeda, María Eugenia; Guisasola, Albert; Baeza, Juan A; Fabregat, Azael; Stüber, Frank; Fortuny, Agustí; Font, Josep; Carrera, Julián

    2007-02-01

    This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass.

  15. Low-pressure catalytic wet-air oxidation of a high-strength industrial wastewater using Fenton's reagent.

    Science.gov (United States)

    Biçaksiz, Zeliha; Aytimur, Gülin; Atalay, Süheyda

    2008-06-01

    Wastewater from the Afyon Alkaloids Factory (Afyon, Turkey) was subjected to low-pressure catalytic wet-air oxidation (CWAO) using Fenton's reagent, and the optimal reaction conditions were investigated. The CWAO using Fenton's reagent was applied to the factory effluent, diluted factory effluent, and aerobically pretreated wastewater. To find the optimum quantities of reagents, ferrous iron (Fe(+2))-to-substrate ratios of 1:10, 1:25, and 1:50 and hydrogen peroxide (H2O2)-to-Fe(+2) ratios of 1, 5, and 10 were investigated, and the treatment was carried out at different temperatures. High chemical oxygen demand (COD) removals were obtained at 50 degrees C, with the Fe(+2)-to-substrate ratio range between 1:10 and 1:25. The change in H2O2-to-Fe(+2) ratios did not cause any considerable effect. Also, the percentages of COD removals were nearly the same, so the ratio H2O2:Fe(+2):1 is recommended. Aerobic pretreatment seems to be effective. On the other hand, no enhancement was observed in the case of the diluted wastewater.

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

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson Tedgren, Aasa

    2007-11-15

    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

  17. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources; Importancia del coeficiente de kerma de neutrones en la planeacion de tratamientos de Braquiterapia con fuentes de Cf-252

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L.; Balcazar G, M. [ININ, 52045 Ocoyocac, Estado de Mexico (Mexico); Azorin N, J. [Universidad Autonoma Metropolitana, 09000 Mexico D.F. (Mexico); Francois L, J.L. [UNAM, 04500 Mexico D.F. (Mexico)]. e-mail: lpg@nuclear.inin.mx

    2006-07-01

    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 10{sup 6} n/s-{mu}g 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 E{sub n} > 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 E{sub n} > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of {sup 252}Cf, to optimize and to individualize the patients treatments. (Author)

  18. 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

  19. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Pignol, J.-P. [Toronto-Sunnybrook Regional Cancer Centre, Radiotherapy Dept., Toronto, Ontario (Canada); Slabbert, J. [National Accelerator Centre, Faure (South Africa)

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,{alpha}) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends. (author)

  20. 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)

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

    Science.gov (United States)

    Matyssek, R; Wieser, G; Ceulemans, R; Rennenberg, H; Pretzsch, H; Haberer, K; Löw, M; Nunn, A J; Werner, H; Wipfler, P; Osswald, W; Nikolova, P; Hanke, D E; Kraigher, H; Tausz, M; Bahnweg, G; Kitao, M; Dieler, J; Sandermann, H; Herbinger, K; Grebenc, T; Blumenröther, M; Deckmyn, G; Grams, T E E; Heerdt, C; Leuchner, M; Fabian, P; Häberle, K-H

    2010-08-01

    Ground-level ozone (O(3)) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O(3)-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O(3) exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O(3) levels. Elevated O(3) 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 O(3) 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 O(3) can substantially mitigate the C sequestration of forests in view of climate change.

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

    Energy Technology Data Exchange (ETDEWEB)

    Matyssek, R., E-mail: matyssek@wzw.tum.d [Ecophysiology of Plants, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Wieser, G. [Dept. Alpine Timberline Ecophysiology, Federal Office and Research Centre for Forests, Rennweg 1, A-6020 Innsbruck (Austria); Ceulemans, R. [Dept. of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Rennenberg, H. [Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler-Allee 53, D-79110 Freiburg (Germany); Pretzsch, H. [Forest Growth and Yield Sciences, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Haberer, K. [Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler-Allee 53, D-79110 Freiburg (Germany); Loew, M.; Nunn, A.J. [Ecophysiology of Plants, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Werner, H. [Ecoclimatology (formerly: Bioclimatology and Air Pollution Research), Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Wipfler, P. [Forest Growth and Yield Sciences, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Osswald, W. [Phytopathology of Woody Plants, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Nikolova, P. [Ecophysiology of Plants, Technische Universitaet Muenchen, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising (Germany); Hanke, D.E. [Dept. Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA (United Kingdom); Kraigher, H. [Slovenian Forestry Institute, Forest Biology, Ecology and Technology, Vecna pot 2, 1000 Ljubljana (Slovenia); Tausz, M. [Dept. of Forest and Ecosystem Science, Melbourne School of Land and Environment, Water Street, Creswick Vic 3363 (Australia)

    2010-08-15

    Ground-level ozone (O{sub 3}) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O{sub 3}-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O{sub 3} exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O{sub 3} levels. Elevated O{sub 3} 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 O{sub 3} 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 O{sub 3} 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 O{sub 3} impact for adult beech.

  3. PTRAC File Utilization for Calculation of Free-Air Ionization Chamber Correction Factors by MCNPX

    Science.gov (United States)

    Šolc, Jaroslav; Sochor, Vladimír

    2014-06-01

    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 (kloss) and for additional ionization current caused by photon scatter (ksc), photon fluorescence (kfl), photon transmission through diaphragm edge (kdtr), and photon scatter from the surface of the diaphragm aperture (kdsc) 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 a literature for similar free-air chambers.

  4. 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.

  5. 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.

  6. Recoil proton, alpha particle, and heavy ion impacts on microdosimetry and RBE of fast neutrons: analysis of kerma spectra calculated by Monte Carlo simulation.

    Science.gov (United States)

    Pignol, J P; Slabbert, J

    2001-02-01

    Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,alpha) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.

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

    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 Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    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)

  8. 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)

  9. 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.

  10. Application Prospects of High Strength Low-alloyed Steels to Sheet Metal of Air-conditioner%低合金高强度钢在空调钣金件中的应用前景

    Institute of Scientific and Technical Information of China (English)

    龙江; 蒋子琪

    2014-01-01

    本文主要介绍了低合金高强度钢的特点,从实际的加工性、防腐性和成本方面进行分析,并以某款家用空调器电机支架为例使用屈服强度在350MPa级的低合金高强度钢进行试验验证,结果表明低合金高强度钢在空调的钣金件加工中有较高的可行性和较好的应用前景%In the paper, The characteristics of high strength low-alloyed steels are mainly introduced.The actu-al machinability, corrosion resistance and cost are analyzed and the experimental verification have been taken by a certain motor support of high strength low-alloyed steels with yield strength of 350MPa level, it indicated that the high strength low-alloyed steels have higher feasibilities and more application prospects in sheet metal of air-conditioner.

  11. Correction factors for source strength determination in HDR brachytherapy using the in-phantom method

    Energy Technology Data Exchange (ETDEWEB)

    Ubrich, Frank; Engenhart-Cabillic, Rita [University Hospital Giessen-Marburg, Marburg (Germany). Dept. of Radiotherapy and Radiation Oncology; Wulff, Joerg [University of Applied Sciences (THM) Giessen (Germany). Inst. of Medical Physics and Radiation Protection (IMPS); Zink, Klemens [University Hospital Giessen-Marburg, Marburg (Germany). Dept. of Radiotherapy and Radiation Oncology; University of Applied Sciences (THM) Giessen (Germany). Inst. of Medical Physics and Radiation Protection (IMPS)

    2014-09-01

    For the purpose of clinical source strength determination for HDR brachytherapy sources, the German society for Medical Physics (DGMP) recommends in their report 13 the usage of a solid state phantom (Krieger-phantom) with a thimble ionization chamber. In this work, the calibration chain for the determination of the reference air-kerma rate K{sub a,100} and reference dose rate to water D{sub w,1} by ionization chamber measurement in the Krieger-phantom was modeled via Monte Carlo simulations. These calculations were used to determine global correction factors k{sub tot}, which allows a user to directly convert the reading of an ionization chamber calibrated in terms of absorbed dose to water, into the desired quantity K{sub a,100} or D{sub w,1}. The factor k{sub tot} was determined for four available {sup 192}Ir sources and one {sup 60}Co source with three different thimble ionization chambers. Finally, ionization chamber measurements on three μSelectron V2 HDR sources within the Krieger-phantom were performed and K{sub a,100} was determined according to three different methods: (1) using a calibration factor in terms of absorbed dose to water wth the global correction factor (k{sub tot}){sub K{sub a{sub ,{sub 1{sub 0{sub 0}}}}}} according DGMP 13 (2) using a global correction factor calculated via Monte Carlo (3) using a direct reference air-kerma rate calibration factor determined by the national metrology institute PTB. The comparison of Monte Carlo based (k{sub tot}){sub K{sub a{sub ,{sub 1{sub 0{sub 0}}}}}} with those from DGMP 13 showed that the DGMP data were systematically smaller by about 2-2.5%. The experimentally determined (k{sub tot}){sub K{sub a{sub ,{sub 1{sub 0{sub 0}}}}}}, based on the direct K{sub a,100} calibration were also systematically smaller by about 1.5%. Despite of these systematical deviations, the agreement of the different methods was in almost all cases within the 1σ level of confidence of the interval of their respective

  12. Strength Training

    Science.gov (United States)

    ... en español Entrenamiento de la fuerza muscular Strength training is a vital part of a balanced exercise routine that includes aerobic activity and flexibility exercises. Regular aerobic exercise, such as running or ...

  13. Strength Training

    Science.gov (United States)

    ... strengthens your heart and lungs. When you strength train with weights, you're using your muscles to ... see there are lots of different ways to train with weights. Try a few good basic routines ...

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

    Science.gov (United States)

    Chu, Chien-Hau; Kuan, Wei-Peng; Kurosawa, T; Lin, Uei-Tyng; Chen, Ing-Jane; Chen, Wei-Li

    2010-02-01

    The National Radiation Standard Laboratory of the Institute 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 Institute of Advanced Industrial Science and Technology (AIST) experimental results comparison using a transfer chamber yielded a difference energy X-ray calibration services in Taiwan and even forming a basis for the future mammography X-ray air-kerma primary standard.

  15. 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)

  16. Kinetics of Passive Oxidation of Hi-Nicalon-S SiC Fibers in Wet Air: Relationships between Si02 Scale Thickness, Crystallization, and Fiber Strength (Preprint)

    Science.gov (United States)

    2012-07-01

    crystallize to cristobalite and tridymite in 100 hours at 1000°C or in one hour at 1300°C. Crystallization kinetics for oxidation in wet air were...measured by TEM. Oxidation initially produces an amorphous scale that starts to crystallize to cristobalite and tridymite in 100 hours at 1000°C or in...using reflected light interference fringes observed by optical microscopy. Cross-sectional TEM specimens were prepared from oxidized fibers by

  17. Characterization of a free air ionization chamber for low energy X-rays

    Science.gov (United States)

    Silva, N. F.; Xavier, M.; Vivolo, V.; Caldas, L. V. E.

    2016-07-01

    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.

  18. 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)

  19. Compressive Strength of 2D-C/SiC Composite at High Temperature in Air%2D-C/SiC复合材料在空气中的高温压缩强度研究

    Institute of Scientific and Technical Information of China (English)

    牛学宝; 张程煜; 乔生儒; 韩栋; 李玫

    2011-01-01

    研究了二维碳纤维增强碳化硅基复合材料(2 D-C/SiC)在空气介质中的高温压缩强度.材料采用1K T300碳纤维平纹布经叠层和缝合制成预制体为增强体,经等温化学气相浸渗制备而成.试样表面用化学气相沉积工艺沉积SiC涂层.测试方向为垂直于炭布叠层方向,测试温度为室温,700℃,1100℃和1300℃.使用扫描电子显微镜观察了材料的断口.结果表明:室温~700℃,2D-C/SiC的压缩强度随温度升高逐渐增大,温度高于700℃后,材料的压缩强度缓慢降低.导致2D-C/SiC的压缩强度随温度变化的主要原因为纤维和基体热膨胀系数不同引起的残余应力随温度升高逐渐变小和高温下材料的氧化损伤.%The compressive strength of a two dimensional carbon fiber reinforced silicon carbide composite (2D-C/SiC) at elevated temperature in air was studied. The plain weaved carbon cloth was applied as reinforcement, made of stacked and seamed 1K T300 carbon fiber cloth. The 2D-C/SiC was prepared by isothermal chemical vapor infiltration. The specimens were coated with SiC by chemical vapor deposition. The tests were conducted at room temperature, 700°C , 1100°C and 1300°C respectively, and the loading direction was perpendicular to 2D-C/SiC plane. The fractured surface of the specimens was observed by a scanning electron microscope. The results show that the compressive strength increases gradually with increasing the temperature from room temperature to 700°C , while it decreases gradually when the temperature was above 700°C. The residual stress caused by the mismatch between the thermal expansion coefficients of the fiber and matrix, and the oxidation products play important roles in determining the compressive strength.

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

    Science.gov (United States)

    Groetz, J-E; Ounoughi, N; Mavon, C; Belafrites, A; Fromm, M

    2014-08-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr; Mavon, C.; Fromm, M. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Ounoughi, N. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, 25030 Besançon Cedex (France); Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria); Belafrites, A. [Laboratoire de Physique des Rayonnements et Applications, Université de Jijel, B.P. 98 Ouled Aissa, Jijel 18000 (Algeria)

    2014-08-15

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

    Science.gov (United States)

    Groetz, J.-E.; Ounoughi, N.; Mavon, C.; Belafrites, A.; Fromm, M.

    2014-08-01

    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.

  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. 一种外掺新型引气剂的水泥胶砂抗折强度试验研究%A Study on the Bending Strength Test of Cement Mortar Added in a New Type of Air Entraining Agent

    Institute of Scientific and Technical Information of China (English)

    李铁军; 郭红兵

    2014-01-01

    In order to improve the mechanical property of cement mortar, admixtures are pro-posed to be put into cement mortar by adding air-entraining agent separately or mixing air en-training agent and water-reducing agent. The bending strength test of cement mortar has been done. The best model and the optimal dosage of air entraining agent in cement mortar have been determined for its optimal mechanical property. The result shows that the bending strength of cement mortar is significantly greater when air entraining agent and water-reducing agent are mixed. 2 # air-entraining agent has better effect in meeting the requirements of the bending strength of cement mortar.%为了提高水泥胶砂的力学性能,提出在水泥胶砂中掺加外加剂的方法,通过在水泥胶砂中单掺引气剂、复掺引气剂与减水剂两种途径,进行水泥胶砂抗折强度检测试验,对比确定水泥胶砂力学性能最优的引气剂型号及其最佳掺量。结果表明:引气剂与减水剂复掺时水泥胶砂的抗折强度明显大于引气剂单掺时水泥胶砂的抗折强度,2#引气剂最能满足水泥胶砂抗折强度要求。

  5. 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

  6. 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)

  7. FATIGUE STRENGTH OF HIGH-STRENGTH STEEL,

    Science.gov (United States)

    coldhardened by deforming to 83%. It was found that it has low static notch sensitivity (lower than that of heat-treated steels), that static strength ...is raised appreciably by increased cold plastic deformation, and that its fatigue strength is raised substantially by mechanical polishing. (Author)

  8. Strength and Balance Exercises

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Strength and Balance Exercises Updated:Sep 8,2016 If ... Be Safe While Being Active - Stretching & Flexibility Exercises - Strength & Balance Exercises - Problems & Solutions for Being Active - FAQs ...

  9. Strength Training for Girls.

    Science.gov (United States)

    Connaughton, Daniel; Connaughton, Angela; Poor, Linda

    2001-01-01

    Strength training can be fun, safe, and appropriate for young girls and women and is an important component of any fitness program when combined with appropriate cardiovascular and flexibility activities. Concerns and misconceptions regarding girls' strength training are discussed, presenting general principles of strength training for children…

  10. The strength compass

    DEFF Research Database (Denmark)

    Ledertoug, Mette Marie

    Individual paper presentation: The ‘Strength Compass’. The results of a PhDresearch project among schoolchildren (age 6-16) identifying VIAstrengths concerning age, gender, mother-tongue-langue and possible child psychiatric diagnosis. Strengths-based interventions in schools have a theoretical...... foundation in research in VIA-strengths by Seligman & Peterson (2004) and in research on strengths by Linley (2008). Based on this research the VIA-test was created for adults and later for children and youths from the age of 10. For children younger than 10 years of age Peterson & Park (2011) have made...... interviews with the parents. For younger children there has been no possibility to test for strengths. In a Danish PhD project a tool to map children’s strengths was needed for children aged 6-16 and with permission from the VIA-institute ‘The Strength Compass’ was made in cooperation with The Danish...

  11. Strength Modeling Report

    Science.gov (United States)

    Badler, N. I.; Lee, P.; Wong, S.

    1985-01-01

    Strength modeling is a complex and multi-dimensional issue. There are numerous parameters to the problem of characterizing human strength, most notably: (1) position and orientation of body joints; (2) isometric versus dynamic strength; (3) effector force versus joint torque; (4) instantaneous versus steady force; (5) active force versus reactive force; (6) presence or absence of gravity; (7) body somatotype and composition; (8) body (segment) masses; (9) muscle group envolvement; (10) muscle size; (11) fatigue; and (12) practice (training) or familiarity. In surveying the available literature on strength measurement and modeling an attempt was made to examine as many of these parameters as possible. The conclusions reached at this point toward the feasibility of implementing computationally reasonable human strength models. The assessment of accuracy of any model against a specific individual, however, will probably not be possible on any realistic scale. Taken statistically, strength modeling may be an effective tool for general questions of task feasibility and strength requirements.

  12. 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...

  13. Strength of Plastics,

    Science.gov (United States)

    evaluating the strength of structural elements is examined. The book is intended for design engineers, factory laboratory personnel, scientific research workers, and the design institutes. (Author-PL)

  14. Strength Training and Your Child

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Strength Training and Your Child KidsHealth > For Parents > Strength ... help prevent injuries and speed up recovery. About Strength Training Strength training is the practice of using ...

  15. Strength Training and Your Child

    Science.gov (United States)

    ... Feeding Your 1- to 2-Year-Old Strength Training and Your Child KidsHealth > For Parents > Strength Training ... prevent injuries and speed up recovery. About Strength Training Strength training is the practice of using free ...

  16. Building on Our Strengths.

    Science.gov (United States)

    Hill, Robert

    1978-01-01

    Comments on the feeling that the American family is disintegrating, and that many criticisms traditionally made about Black families are now made about White families. Suggests that people need to stress family strengths. As an example, five major strengths of Black families are described: flexibility, work and achievement ethics, religiosity, and…

  17. Strengths of Remarried Families.

    Science.gov (United States)

    Knaub, Patricia Kain; And Others

    1984-01-01

    Focuses on remarried families' (N=80) perceptions of family strengths, marital satisfaction, and adjustment to the remarried situation. Results indicated that although most would like to make some changes, scores on the measurements used were high. A supportive environment was the most important predictor of family strength and success. (JAC)

  18. Application of high strength sonic soot blower in air preheater of 1 000 MW units%高强声波吹灰器在1000 MW机组空预器中的应用

    Institute of Scientific and Technical Information of China (English)

    李彦民; 王俊杰

    2016-01-01

    There are some problems existed in the running of air preheater in CLP vote of Henan Electric Power co. LTD. ,Pingdingshan Power 2 x 1 000 MW ultra supercritical units. The air preheater had a large amount of dust ,so the resistance increased which is one of the important reasons affecting the safe and economic opera-tion. The sonic soot blower is applied in air preheater to prevent the dust and its effect is analyzed. The practi-cal application results show that the efficient acoustic wave sootblower are deposited in the air preheater and has obvious effect, the safety benefit, economic benefit and social benefit are remarkable.%介绍了中电投河南电力有限公司平顶山发电分公司2×1000 MW超超临界机组空预器在运行中出现的大量积灰情况,空预器阻力的大幅增加是影响机组安全、经济运行的重要原因。分析通过空预器加装声波吹灰器后对防止空预器大量积灰的效果,根据实践应用结果表明,高效声波吹灰器对空预器积灰有明显效果,安全效益、经济效益及社会效益显著。

  19. 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.

  20. 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 ...

  1. 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.

  2. Strength of Hard Alloys,

    Science.gov (United States)

    Partial replacement of titanium carbide by tantalum carbide in three-phase WC-TiC-Co alloys tends to have a favorable effect on mechanical properties such as fatigue strength under bending and impact durability.

  3. 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.

  4. 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.

  5. Spin Resonance Strength Calculations

    Science.gov (United States)

    Courant, E. D.

    2009-08-01

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  6. Spin resonance strength calculations

    Energy Technology Data Exchange (ETDEWEB)

    Courant,E.D.

    2008-10-06

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  7. High strength alloys

    Science.gov (United States)

    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.

  8. 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......-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 to mid...

  9. 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 ...

  10. Notch strength of composites

    Science.gov (United States)

    Whitney, J. M.

    1983-01-01

    The notch strength of composites is discussed. The point stress and average stress criteria relate the notched strength of a laminate to the average strength of a relatively long tensile coupon. Tests of notched specimens in which microstrain gages have been placed at or near the edges of the holes have measured strains much larger that those measured in an unnotched tensile coupon. Orthotropic stress concentration analyses of failed notched laminates have also indicated that failure occurred at strains much larger than those experienced on tensile coupons with normal gage lengths. This suggests that the high strains at the edge of a hole can be related to the very short length of fiber subjected to these strains. Lockheed has attempted to correlate a series of tests of several laminates with holes ranging from 0.19 to 0.50 in. Although the average stress criterion correlated well with test results for hole sizes equal to or greater than 0.50 in., it over-estimated the laminate strength in the range of hole sizes from 0.19 to 0.38 in. It thus appears that a theory is needed that is based on the mechanics of failure and is more generally applicable to the range of hole sizes and the varieties of laminates found in aircraft construction.

  11. 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...

  12. Character strengths and virtues

    OpenAIRE

    2015-01-01

    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 l...

  13. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...... of Aalborg Clay by use of triaxial tests from four different locations. Both the drained strength (c and ϕ) and the undrained strength (cu) are assessed through two different methods: one where the strength is assumed to vary with the effective stress and another where the strength is found to be constant....

  14. FIELD STRENGTH MEASUREMENTS, PHASE I.

    Science.gov (United States)

    The program included the testing and evaluation of commercial and military field- strength meters. It also included a study of the interpretation of...field- strength measurement data taken under multipath conditions. As part of the field- strength meter evaluation, five instruments, the AN/TRM-7, NF...interpretation of the measured data is the variability of field- strength values obtained over an area. Such variability is caused by the presence of multipath

  15. Strength of Rewelded Inconel 718

    Science.gov (United States)

    Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

    1982-01-01

    Inconel 718, nickel-based alloy used extensively for high-temperature structural service, welded repeatedly without detriment to its strength. According to NASA report, tests show 12 repairs on same weld joint do not adversely affect ultimate tensile strenth, yield strength, fatigue strength, metallurgical grain structures, or ability of weld joint to respond to post weld heat treatments.

  16. Strength Training and Children's Health.

    Science.gov (United States)

    Faigenbaum, Avery D.

    2001-01-01

    Provides an overview of the potential health benefits of strength training for children, discussing the role of strength training in preventing sports-related injuries and highlighting design considerations for such programs. The focus is on musculoskeletal adaptations to strength training that are observable in healthy children. Guidelines for…

  17. Força de preensão palmar e pinça digital em diferentes grupos de pilotos da Academia da Força Aérea brasileira Grip and pinch strength among different groups of Brazilian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Gláucia Helena Gonçalves

    2010-06-01

    Full Text Available Pilotos da Academia de Força Aérea (AFA brasileira, durante vôos, realizam movimentos com grande solicitação da musculatura da mão que comanda o manche, o que pode modificar a força muscular. Este estudo teve por objetivo analisar as forças musculares isométricas de preensão palmar e pinças polpa-a-polpa, trípode e lateral de três grupos de pilotos da AFA. Foram avaliados 15 pilotos da Esquadrilha da Fumaça (EDA, 16 instrutores de vôo (PI e 6 pilotos em treinamento (PT, todos do sexo masculino. Para a avaliação, o posicionamento corporal dos pilotos seguiu a padronização da Sociedade Americana de Terapeutas da Mão e a ordem dos movimentos analisados foi predefinida, evitando fadiga muscular. A força muscular isométrica máxima foi coletada em uma contração sustentada por 6 segundos. Os resultados mostram diferenças significativas na preensão, com superioridade das mãos dominantes em relação às não-dominantes em todos os grupos, tendo ainda o grupo EDA obtido valores significativamente superiores em relação aos demais. Nas medidas da pinça trípode, o grupo EDA apresentou significativos valores superiores aos do grupo PT, sendo encontrados valores das mãos dominantes superiores aos das não-dominantes nos grupos EDA e PI. Conclui-se que o treino específico da musculatura da mão durante o vôo, a especificidade e o período de treinamento interferem na força muscular isométrica da mão.Pilots from Brazilian Air Force Academy (AFA perform strentgth- and accuracy-demanding hand movements, which may modify muscle strength. The aim of this study was to analyse hand isometric strength of grip and pulp-to-pulp, tripode and lateral pinch in three groups of male AFA pilots: ADS (Air Demonstration Squadron, n=15; IP (instructor pilots, n=16; and TP (training pilots, n=6. Pilots body positioning during tests followed the standards of the American Society of Hand Therapists; the sequence of assessed movements was

  18. Effect of silica coating on flexural strength of fiber posts

    NARCIS (Netherlands)

    Valandro, LF; Ozcan, M; de Melo, RM; Galhano, GAP; Baldissara, P; Scotti, R; Bottino, MA

    2006-01-01

    Purpose: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. Materials and Methods: Six experimental groups of FRC posts (

  19. On strength of porous material

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1999-01-01

    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...... to the theoretical research on non-destructive testing of such materials relating strength to stiffness and pore geometry.It is demonstrated that solutions for stiffness, tensile strength, and pore strength (damaging pore pressure, frost, fire) for some ideal porous materials can be determined theoretically only...... from knowing about pore geometry, solid phase stiffness, and zero-porosity strength. Pore geometry is the very important common denominator which controls both both stiffness and strength.The accurate results obtained are finally used to suggest generalizations with respect to strength in general...

  20. 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 $1.108\\pm 0.13\\%\\textrm{cGyh}^{-1} \\textrm{U}^{-1}$.

  1. 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)

  2. 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-. 

  3. FIELD STRENGTH MEASUREMENTS, PHASE II.

    Science.gov (United States)

    The measurement of the strength of radio frequency fields at high frequency and above has followed practices which are standard for the measurement...of field strength at medium and low frequencies. Variability of measurements made in practical situations and a lack of reproducibility of...measurements made under apparently identical conditions has prompted an investigation of equipment and methods used in the determinations. The field strength

  4. 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...... and 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....

  5. 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

    2010-01-01

    The development of mechanical properties has been studied in a test program comprising 15 different concrete mixes with 3 different w/c ratios and different additions of superabsorbent polymers (SAP). The degree of hydration is followed for 15 corresponding paste mixes. This paper concerns...... compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP...... on 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 SAP additions, SAP increases the compressive strength at later ages (from 3 days after casting and onwards...

  6. Physiological Effects of Strength Training and Various Strength Training Devices.

    Science.gov (United States)

    Wilmore, Jack H.

    Current knowledge in the area of muscle physiology is a basis for a discussion on strength training programs. It is now recognized that the expression of strength is related to, but not dependent upon, the size of the muscle and is probably more related to the ability to recruit more muscle fibers in the contraction, or to better synchronize their…

  7. 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.

  8. 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.

  9. 40 CFR 63.524 - Standards for wet strength resins manufacturers.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for wet strength resins... National Emission Standards for Hazardous Air Pollutants for Epoxy Resins Production and Non-Nylon Polyamides Production § 63.524 Standards for wet strength resins manufacturers. (a) Owners or operators...

  10. Bond strength of adhesives to dentin contaminated with smoker's saliva.

    Science.gov (United States)

    Pinzon, Lilliam M; Oguri, Makoto; O'Keefe, Kathy; Dusevish, Vladimir; Spencer, Paulette; Powers, John M; Marshall, Grayson W

    2010-02-01

    The purpose of this study was to determine the effects of contamination with smoker's and non-smoker's saliva on the bond strength of resin composite to superficial dentin using different adhesive systems. The interfacial structure between the resin and dentin was evaluated for each treatment using environmental scanning electron microscopy (ESEM). Freshly extracted human molars were ground with 600-grit SiC paper to expose the superficial dentin. Adhesives [One-Up-Bond-F-Plus (OUFP) and Adper-Prompt-L-Pop (APLP)] and resin composite (TPHSpectrum) were bonded to the dentin (n = 8/group, 180 total specimens) under five surface conditions: control (adhesive applied following manufacturers' instructions); saliva, then 5-s air dry, then adhesive; adhesive, saliva, 5-s air dry; adhesive, saliva, 5-s water rinse, 5-s air dry (ASW group); and adhesive, saliva, 5-s water rinse, 5-s air dry, reapply adhesive (ASWA group). After storage in water at 37 degrees C for 24 h, the specimens were debonded under tension at a speed of 0.5 mm/min. ESEM photomicrographs of the dentin/adhesive interfaces were taken. Mean bond strength ranged from 8.1 to 24.1 MPa. Fisher's protected least significant difference (P = 0.05) intervals for critical adhesive, saliva, and surface condition differences were 1.3, 1.3, and 2.1 MPa, respectively. There were no significant differences in bond strength to dentin between contamination by smoker's and nonsmoker's saliva, but bond strengths were significantly different between adhesive systems, with OUFP twice as strong as APLP under almost all conditions. After adhesive application and contamination with either smoker's or nonsmoker's saliva followed by washing and reapplication of the adhesive (ASWA group), the bond strength of both adhesive systems was the same as that of the control group.

  11. 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...

  12. 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....

  13. Residual Compressive Strength of Laterized Concrete Subjected to Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Robert M. Brooks

    2010-05-01

    Full Text Available This research presents the results of an experimental program to investigate the strength performance of laterized concrete (LATCON when subjected to elevated temperatures of 200, 400 and 600ºC. Six concrete mixes incorporating 0, 10, 20, 30, 40 and 50% Laterite as a replacement by weight of sand was prepared. After heat pretreatment specimens were cooled using either rapid cooling (water-cooling or natural cooling (air-cooling. An analysis of variance test shows that exposure temperature, cooling regime, and their interaction have a significant influence on the compressive strength of the samples. When subjected to the investigated temperatures specimens experienced strength losses that increased with temperature. This study further reveals that air-cooled concrete specimens maintained higher residual strength values than water-cooled specimens. A comparison of the residual compressive strength data obtained in this study with code provisions in Eurocode and CEB design curve shows that these codes could be applied to LATCON subjected to temperature below 400ºC.

  14. 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.

  15. STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

    Directory of Open Access Journals (Sweden)

    NOZEMTСEV Alexandr Sergeevich

    2013-02-01

    Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

  16. Effect of Different Surface Treatment on Shear Bond Strength of Veneering Composite to Polyetherketone Core Material

    Directory of Open Access Journals (Sweden)

    Hossein Pourkhalili

    2016-12-01

    Full Text Available Background and Objective:The purpose of this in vitro study was to assess the effect of different surface treatment methods on shear bond strength of the veneering composite to polyetheretherketone (PEEK core material. Materials and Methods::In this in vitro, experimental study, 60 PEEK discs were fabricated, polished with silicon carbide abrasive paper and divided into five surface treatment groups (n=12 namely air abrasion with 110µm alumina particles at 0.2MPa pressure for 10 seconds, 98% sulfuric acid etching for one minute, air abrasion plus sulfuric acid etching, application of cyanoacrylate resin and a no surface treatment control group. Visio.link adhesive and GC Gradia veneering composite were applied on PEEK surfaces and light-cured. Shear bond strength was measured using a universal testing machine and the data were analyzed by one-way ANOVA and Tukey’s test. Results:The mean ± standard deviation (SD values of shear bond strength of the veneering composite to PEEK surfaces were 8.85±3.03, 15.6±5.02, 30.42±5.43, 26.14±4.33 and 5.94±4.49MPa in the control, air-abrasion, sulfuric acid etching, air-abrasion plus sulfuric acid etching and cyanoacrylate resin groups, respectively. The control and cyanoacrylate groups had significant differences with air abrasion, sulfuric acid etching and air abrasion plus sulfuric acid etching groups in terms of shear bond strength (P<0.0001. Higher bond strength values were noted in sulfuric acid etching, air-abrasion plus sulfuric acid etching and air abrasion groups compared to the control and cyanoacrylate groups (P<0.0001. Conclusion:Sulfuric acid etching, air abrasion and a combination of both are recommended as efficient surface treatments to increase the shear bond strength of the veneering composite to PEEK core material.

  17. 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.

  18. The Antifreeze Critical Strength of Low-temperature Concrete Effected by Index

    Institute of Scientific and Technical Information of China (English)

    LIU Jun; LIU Yu; LIU Runqing

    2011-01-01

    The antifreeze critical strength and the pre-curing time of low-temperature concrete were studied by means of guaranteed rate of compressive strength and antifreeze performance for the structural safety requirement of concrete engineering, suffering once freeze damage under air environment. It is shown that the antifreeze critical strength is 3.7-4.4 MPa, pre-curing time is 18-32 h by guaranteed rate of compressive strength, and the antifreeze critical strength is 3.7-4.4 MPa, pre-curing time is 18-32 h by guaranteed rate of antifreeze performance. It can be found that the method of guaranteed rate of compressive strength is sensitive to the defect which generated by freeze damage in the concrete interior. The method is fit to evaluate the antifreeze critical strength of low-temperature concrete.

  19. Air Pollution

    Science.gov (United States)

    ... to view this content or go to source URL . What NIEHS is Doing on Air Pollution Who ... Junction Last Reviewed: February 06, 2017 This page URL: NIEHS website: https://www.niehs.nih.gov/ Email ...

  20. Advanced high strength steels for automotive industry

    Directory of Open Access Journals (Sweden)

    Galán, J.

    2012-04-01

    Full Text Available 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 carbody 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.

    La industria del automóvil se enfrenta a una creciente demanda de vehículos de pasajeros más eficientes. Con el fin de disminuir el consumo de energía y la contaminación ambiental, el peso del vehículo tiene que ser reducido, al mismo tiempo que se garantizan altos niveles de seguridad. Ante esta situación, la elección de material se convierte en una decisión crucial en el diseño del vehículo. Como respuesta a las necesidades del sector automovilístico, nuevos aceros avanzados y de alta resistencia, han sido desarrollados por la industria siderúrgica. Dichos tipos de acero ofrecen un excelente equilibrio de precio, peso y propiedades mecánicas.

  1. Muscle Strength and Poststroke Hemiplegia

    DEFF Research Database (Denmark)

    Kristensen, Otto H; Stenager, Egon; Dalgas, Ulrik

    2017-01-01

    OBJECTIVES: To systematically review (1) psychometric properties of criterion isokinetic dynamometry testing of muscle strength in persons with poststroke hemiplegia (PPSH); and (2) literature that compares muscle strength in patients poststroke with that in healthy controls assessed by criterion...... isokinetic dynamometry. DATA SOURCES: A systematic literature search of 7 databases was performed. STUDY SELECTION: Included studies (1) enrolled participants with definite poststroke hemiplegia according to defined criteria; (2) assessed muscle strength or power by criterion isokinetic dynamometry; (3) had...... undergone peer review; and (4) were available in English or Danish. DATA EXTRACTION: The psychometric properties of isokinetic dynamometry were reviewed with respect to reliability, validity, and responsiveness. Furthermore, comparisons of strength between paretic, nonparetic, and comparable healthy muscles...

  2. 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.

  3. 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...

  4. 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).

  5. Lifting strength in two-person teamwork.

    Science.gov (United States)

    Lee, Tzu-Hsien

    2016-01-01

    This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.

  6. Muscle strength in myasthenia gravis

    DEFF Research Database (Denmark)

    Cejvanovic, S; Vissing, J

    2014-01-01

    is 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 (Pstrength 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, Pstrength in shoulder abductors was most affected (51% vs 62...

  7. Strengths, weaknesses, opportunities and threats

    DEFF Research Database (Denmark)

    Bull, J. W.; Jobstvogt, N.; Böhnke-Henrichs, A.;

    2016-01-01

    environmental awareness. Threats include resistance to change, and difficulty with interdisciplinary collaboration. Consideration of SWOT themes suggested five strategic areas for developing and implementing ES.The ES concept could improve decision-making related to natural resource use, and interpretation...... facilitate interdisciplinary research, ensuring decision-making that supports sustainable development........ Such an assessment could form the basis for improving ES thinking, further embedding it into environmental decisions and management.The Young Ecosystem Services Specialists (YESS) completed a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of ES through YESS member surveys. Strengths include the approach...

  8. Strength of Materials and Structures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ All engineering structures designed according to modern principles have to be strong and sufficiently rigid. Scientists and engineers have long recognized the importance of the strength of materials and structures, and dedicated much their efforts to both fundamental and industrial research into the theory for vast engineering materials and various structures. A lot of engineers need to be familiar with the fundamental principles of strength in materials and structures in order to design structures to resist failures. This book is a very good one to provide them with these principles.

  9. Topological strength of magnetic skyrmions

    Science.gov (United States)

    Bazeia, D.; Ramos, J. G. G. S.; Rodrigues, E. I. B.

    2017-02-01

    This work deals with magnetic structures that attain integer and half-integer skyrmion numbers. We model and solve the problem analytically, and show how the solutions appear in materials that engender distinct, very specific physical properties, and use them to describe their topological features. In particular, we found a way to model skyrmion with a large transition region correlated with the presence of a two-peak skyrmion number density. Moreover, we run into the issue concerning the topological strength of a vortex-like structure and suggest an experimental realization, important to decide how to modify and measure the topological strength of the magnetic structure.

  10. 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.

  11. 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...

  12. Modeling of Sylgard Adhesive Strength

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Ralph Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-03

    Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.

  13. Fast electromagnetic field strength probes

    NARCIS (Netherlands)

    Leferink, Frank; Serra, Ramiro

    2013-01-01

    Diode detectors and thermocouple detectors are conventionally used to measure electromagnetic field strength. Both detectors have some disadvantages for applications where a fast response and a high dynamic range is required. The diode detector is limited in dynamic range. The dynamic range is impor

  14. GSPEL - Air Filtration Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Evaluation capabilities for air filtration devices The Air Filtration Lab provides testing of air filtration devices to demonstrate and validate new or legacy system...

  15. Modified Shear Box Test Apparatus for Measuring Shear Strength of Unsaturated Residual Soil

    Directory of Open Access Journals (Sweden)

    Bujang B.K. Huat

    2005-01-01

    Full Text Available Residual soils occur in most countries of the world but the greater areas and depths are normally found in tropical humid areas. Most of these soils exhibit high suctions for most of the year. The shear strength parameters, c’ and Φ’, of soil can be obtained using conventional shear strength tests. However the conventional shear strength test equipments would not be able to measure Φb value (change of shear strength to change in suction without certain modification to them. This study describes the modifications that have been made to a standard shear box test apparatus to enable it to test soil samples in unsaturated conditions. The modifications include fabrication of an air pressure chamber, modifications of the shear box assembly inside the air pressure chamber, modification to the normal loading system, as well as additions of data acquisition devices to enhance the performance and simplify the usage of the modified shear box test apparatus.

  16. Air-to-Air Missile Vector Scoring

    Science.gov (United States)

    2012-03-22

    64 4.6. Unscented Kalman Filter Performance in Air-to-Air Missile Scor - ing Application with Continuous Velocity Dynamics Model (Tar- get...Filter Performance in Air-to-Air Missile Scor - ing Application with Continuous Velocity Dynamics Model (Tar- get Aircraft Executing a Vertical Climb...Kalman Filter Performance in Air-to-Air Missile Scor - ing Application with Continuous Velocity Dynamics Model (Tar- get Aircraft Non-maneuvering

  17. High Strength Discontinuously Reinforced Aluminum For Rocket Applications

    Science.gov (United States)

    Pandey, A. B.; Shah, S. R.; Shadoan, M.

    2003-01-01

    This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.

  18. 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...

  19. 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...

  20. 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...

  1. 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...... 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....

  2. 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.

  3. Air Warfare

    Science.gov (United States)

    2002-03-01

    undoubtedly begat the shield; poisonous gases were countered by the mask. Surely men on the surface of the earth will not have to submit to violent air attack...properties, production methods and cost of helium are given in “Balloon and Airship Gases ,” a volume of the Ronald Aeronautic Library. 5 More complete...becomes and more inse - cure. We shall see later that even some of the men who were advancing in the path prescribed by the principle of mass

  4. Dramatically enhanced electrical breakdown strength in cellulose nanopaper

    Science.gov (United States)

    Huang, Jianwen; Zhou, Yuanxiang; Zhou, Zhongliu; Liu, Rui

    2016-09-01

    Electrical breakdown behaviors of nanopaper prepared from nanofibrillated cellulose (NFC) were investigated. Compared to conventional insulating paper made from micro softwood fibers, nanopaper has a dramatically enhanced breakdown strength. Breakdown field of nanopaper is 67.7 kV/mm, whereas that of conventional paper is only 20 kV/mm. Air voids in the surface of conventional paper are observed by scanning electron microscope (SEM). Further analyses using mercury intrusion show that pore diameter of conventional paper is around 1.7 μ m , while that of nanopaper is below 3 nm. Specific pore size of nanopaper is determined to be approximately 2.8 nm by the gas adsorption technique. In addition, theoretical breakdown strengths of nanopaper and conventional paper are also calculated to evaluate the effect of pore size. It turns out that theoretical values agree well with experimental data, indicating that the improved strength in nanopaper is mainly attributed to the decreased pore size. Due to its outstanding breakdown strength, this study indicates the suitability of nanopaper for electrical insulation in ultra-high voltage convert transformers and other electrical devices.

  5. Dramatically enhanced electrical breakdown strength in cellulose nanopaper

    Directory of Open Access Journals (Sweden)

    Jianwen Huang

    2016-09-01

    Full Text Available Electrical breakdown behaviors of nanopaper prepared from nanofibrillated cellulose (NFC were investigated. Compared to conventional insulating paper made from micro softwood fibers, nanopaper has a dramatically enhanced breakdown strength. Breakdown field of nanopaper is 67.7 kV/mm, whereas that of conventional paper is only 20 kV/mm. Air voids in the surface of conventional paper are observed by scanning electron microscope (SEM. Further analyses using mercury intrusion show that pore diameter of conventional paper is around 1.7 μm, while that of nanopaper is below 3 nm. Specific pore size of nanopaper is determined to be approximately 2.8 nm by the gas adsorption technique. In addition, theoretical breakdown strengths of nanopaper and conventional paper are also calculated to evaluate the effect of pore size. It turns out that theoretical values agree well with experimental data, indicating that the improved strength in nanopaper is mainly attributed to the decreased pore size. Due to its outstanding breakdown strength, this study indicates the suitability of nanopaper for electrical insulation in ultra-high voltage convert transformers and other electrical devices.

  6. Development of various curing effect of nominal strength Geopolymer concrete

    Directory of Open Access Journals (Sweden)

    S. Kumaravel

    2014-04-01

    Full Text Available Geopolymer concrete is an innovative method and is produced by complete elimination of ordinary Portland cement byproduced in fly ash. This study on different condition of curing in geopolymer concrete suitable for curing at ambient and heat-cured condition of temperature will widen its application to concrete structures. Low lime fly ash is used as the base material, which is reacted by alkaline solution and additional use of ground granulated blast furnace slag. Workability of fresh concrete and compressive strength of geopolymer concrete was investigated. The curing effect of geopolymer concrete is steam, hot air and ambient cubes specimens are tested in different days. Results are compared for various curing and strength of concrete.

  7. 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.

  8. Effect of Specimen Shape and Size on the Compressive Strength of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Sudin M.A.S.

    2014-03-01

    Full Text Available Lightweight concrete, in the form of foamed concrete, is a versatile material that primarily consists of a cement based mortar, mixed with at least 20% volume of air. Its dry density is typically below 1600 kg/m3 with a maximum compressive strength of 15MPa. The ASTM standard provision specifies a correction factor for concrete strength of between 14 and 42Mpa, in order to compensate for a reduced strength, when the aspect height-to-diameter ratio of a specimen is less than 2.0. However, the CEB-FIP provision specifically mentions a ratio of 150mm dia. × 300mm cylinder strength to 150 mm cube strength; though, both provision requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength to lightweight concrete (in this case, foamed concrete. The focus of this work is to study the effect of specimen size and shape on the axial compressive strength of concrete. Specimens of various sizes and shapes were cast with square and circular cross-sections i.e., cubes, prisms, and cylinders. Their compression strength behaviours at 7 and 28 days were investigated. The results indicate that, as the CEB-FIP provision specified, even for foamed concrete, 100mm cubes (l/d = 1.0 produce a comparable compressive strength with 100mm dia. × 200mm cylinders (l/d = 2.0.

  9. Strength and durability of concrete with ash aggregate

    Energy Technology Data Exchange (ETDEWEB)

    Basheer, P.A.M.; Bai, Y. [Queens University Belfast, Belfast (United Kingdom)

    2005-06-01

    A previous investigation to replace natural sand in concrete with furnace bottom ash (FBA) from a coal-fired thermal power plant in Northern Ireland, UK indicated that the water demand of fresh concrete decreases with the increase of the FBA content. Therefore, in the current study the water content was decreased for concretes containing FBA for a given slump and a constant cement content of 382 kg/m{sup 3}. The natural sand was replaced with the FBA at 0, 30, 50, 70 and 100% by mass and three slump ranges, 0-10, 10-30 and 30-60 mm, were considered. The water content of the mixes was determined by carrying out trials. The effect of FBA on water demand, density, compressive strength, pull-off tensile strength, abrasion resistance, drying shrinkage, air permeability, sorptivity, carbonation, chloride diffusion and salt scaling resistance of concretes containing FBA was studied. The results indicated that the water demand of fresh concrete decreases with an increase of FBA content while it has no significant effect on density, compressive strength, pull-off tensile strength or abrasion resistance. The air permeability, sorptivity and drying shrinkage increases beyond 30% FBA content, but the resistance to chloride ingress and salt scaling improves. The depth of carbonation also increases with an increase in the FBA content beyond the 30% replacement level. Overall, FBA content up to 30% as fine aggregate can be incorporated in structural concrete with mostly beneficial effects to various properties of concrete, provided the cement content is kept constant and the water content corresponds to that for low-slump concrete mixes.

  10. 78 FR 66903 - Meeting of the National Commission on the Structure of the Air Force

    Science.gov (United States)

    2013-11-07

    ... militia heritage and the history of the Air Force since 1947. This discussion will extend to accounting... between the regular and reserve components of the Air Force, taking advantage of the unique strengths and... States; (d) provides for sufficient numbers of regular members of the Air Force to provide a base...

  11. 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.

  12. Prediction of underwater target strength

    Institute of Scientific and Technical Information of China (English)

    WANG TongQing; Mohammad Amjad

    2001-01-01

    A model as well as its numerical method to calculate target strength of rigid body using Lighthill's acoustic analogy approach which developed from the propeller aircraft sound field study have been presented. The cases of ellipsoid target has been used to demonstrate the approach. The comparison of the numerical results with that of analytical formulation provides a satisfactory check for the validity of the approach. Some reasonable results have been discussed. The advantage of the present model is that it is suitable for any arbitrarily shaped rigid body moving with small Mach number.

  13. High strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  14. 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.

  15. Asteroid airburst altitude vs. strength

    Science.gov (United States)

    Robertson, Darrel; Wheeler, Lorien; Mathias, Donovan

    2016-10-01

    Small NEO asteroids (<Ø140m) may not be a threat on a national or global level but can still cause a significant amount of local damage as demonstrated by the Chelyabinsk event where there was over $33 million worth of damage (1 billion roubles) and 1500 were injured, mostly due to broken glass. The ground damage from a small asteroid depends strongly on the altitude at which they "burst" where most of the energy is deposited in the atmosphere. The ability to accurately predict ground damage is useful in determining appropriate evacuation or shelter plans and emergency management.Strong asteroids, such as a monolithic boulder, fail and create peak energy deposition close to the altitude at which ram dynamic pressure exceeds the material cohesive strength. Weaker asteroids, such as a rubble pile, structurally fail at higher altitude, but it requires the increased aerodynamic pressure at lower altitude to disrupt and disperse the rubble. Consequently the resulting airbursts have a peak energy deposition at similar altitudes.In this study hydrocode simulations of the entry and break-up of small asteroids were performed to examine the effect of strength, size, composition, entry angle, and speed on the resulting airburst. This presentation will show movies of the simulations, the results of peak burst height, and the comparison to semi-analytical models.

  16. Muscle strength in patients with chronic pain

    NARCIS (Netherlands)

    van Wilgen, C.P.; Akkerman, L.; Wieringa, J.; Dijkstra, P.U.

    2003-01-01

    Objective: To analyse the influence of chronic pain on muscle strength. Design: Muscle strength of patients with unilateral nonspecific chronic pain, in an upper or lower limb, were measured according to a standardized protocol using a hand-held dynamometer. Before and after muscle strength measurem

  17. 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…

  18. 14 CFR 31.27 - Strength.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able...

  19. Improving the toughness of ultrahigh strength steel

    Energy Technology Data Exchange (ETDEWEB)

    Soto, Koji

    2002-08-15

    The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors.

  20. Air filtration and indoor air quality

    DEFF Research Database (Denmark)

    Bekö, Gabriel

    2006-01-01

    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....... These 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....

  1. Report of AAPM Therapy Physics Committee Task Group 74: in-air output ratio, Sc, for megavoltage photon beams.

    Science.gov (United States)

    Zhu, Timothy C; Ahnesjö, Anders; Lam, Kwok Leung; Li, X Allen; Ma, Chang-Ming Charlie; Palta, Jatinder R; Sharpe, Michael B; Thomadsen, Bruce; Tailor, Ramesh C

    2009-11-01

    The concept of in-air output ratio (Sc) was introduced to characterize how the incident photon fluence per monitor unit (or unit time for a Co-60 unit) varies with collimator settings. However, there has been much confusion regarding the measurement technique to be used that has prevented the accurate and consistent determination of Sc. The main thrust of the report is to devise a theoretical and measurement formalism that ensures interinstitutional consistency of Sc. The in-air output ratio, Sc, is defined as the ratio of primary collision water kerma in free-space, Kp, per monitor unit between an arbitrary collimator setting and the reference collimator setting at the same location. Miniphantoms with sufficient lateral and longitudinal thicknesses to eliminate electron contamination and maintain transient electron equilibrium are recommended for the measurement of Sc. The authors present a correction formalism to extrapolate the correct Sc from the measured values using high-Z miniphantom. Miniphantoms made of high-Z material are used to measure Sc for small fields (e.g., IMRT or stereotactic radiosurgery). This report presents a review of the components of Sc, including headscatter, source-obscuring, and monitor-backscattering effects. A review of calculation methods (Monte Carlo and empirical) used to calculate Sc for arbitrary shaped fields is presented. The authors discussed the use of Sc in photon dose calculation algorithms, in particular, monitor unit calculation. Finally, a summary of Sc data (from RPC and other institutions) is included for QA purposes.

  2. 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.

  3. Cobalt: for strength and color

    Science.gov (United States)

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  4. Air pollution

    Energy Technology Data Exchange (ETDEWEB)

    1974-12-01

    Air pollution conditions in Iwakuni city were monitored at 9 monitoring stations, and 21 locations where sulfur oxides were measured by the lead peroxide candle method, and 13 locations where particulates concentrations were determined by the deposit cage method. The average SO/sub x/ concentrations in 1973 measured by the lead peroxide candle method ranged from 0.17 mg sulfur trioxide/day/100 sq cm at the Miso Office to 0.58 mg SO/sub 3//day/100 sq cm at Mitsui Sekiyu Shataku. The average SO/sub x/ concentrations measured by the conductivity method ranged from 0.021 ppM at Kazuki Kominkan to 0.037 ppM at the Higashi Fire Department. Only 58% of a total of 264 measurement days gave hourly average concentrations below the environmental standard of 0.04 ppM at the Higashi Fire Deparment. The average airborne particulate concentrations ranged from 0.050 mg/cu m at Totsu Kominkan to 0.056 mg/cu at the Higashi Fire Department. The average nitrogen oxides concentrations measured by the Saltzman method ranged from 0.007 ppM to 0.061 ppM. The average oxidant concentrations at the Iwakuni Municipal Office and Kazuki Kominkan were 0.028 ppM and 0.037 ppM, respectively.

  5. 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.

  6. The Distribution of Subjective Memory Strength: List Strength and Response Bias

    Science.gov (United States)

    Criss, Amy H.

    2009-01-01

    Models of recognition memory assume that memory decisions are based partially on the subjective strength of the test item. Models agree that the subjective strength of targets increases with additional time for encoding however the origin of the subjective strength of foils remains disputed. Under the fixed strength assumption the distribution of…

  7. The Mean Remaining Strength Of Systems In A Stress-Strength Model

    OpenAIRE

    Gürler, Selma

    2014-01-01

    In this paper, we study the mean remaining strength of a component inthe stress-strength setup. We present the models for the mean remaining strength for systems consisting of n independent components underthe k-out-of-n:F , parallel and series configurations. We assume thatthe strengths of the components are nonidentically distributed randomvariables and components are designed under the common stress.

  8. Air Sensor Toolbox

    Science.gov (United States)

    Air Sensor Toolbox provides information to citizen scientists, researchers and developers interested in learning more about new lower-cost compact air sensor technologies and tools for measuring air quality.

  9. 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 ...

  10. GSPEL - Air Filtration Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Evaluation capabilities for air filtration devicesThe Air Filtration Lab provides testing of air filtration devices to demonstrate and validate new or legacy system...

  11. Lead (Pb) Air Pollution

    Science.gov (United States)

    ... States Environmental Protection Agency Search Search Lead (Pb) Air Pollution Share Facebook Twitter Google+ Pinterest Contact Us As ... and protect aquatic and terrestrial ecosystems. Lead (Pb) Air Pollution Lead Air Pollution Basics How does lead get ...

  12. AirPEx: Air Pollution Exposure Model

    OpenAIRE

    Freijer JI; Bloemen HJTh; de Loos S; Marra M; Rombout PJA; Steentjes GM; Veen MP van; LBO

    1997-01-01

    Analysis of inhalatory exposure to air pollution is an important area of investigation when assessing the risks of air pollution for human health. Inhalatory exposure research focuses on the exposure of humans to air pollutants and the entry of these pollutants into the human respiratory tract. The principal grounds for studying the inhalatory exposure of humans to air pollutants are formed by the need for realistic exposure/dose estimates to evaluate the health effects of these pollutants. T...

  13. Correlation between the strength of glass ionomer cements and their bond strength to bovine teeth.

    Science.gov (United States)

    Hibino, Yasushi; Kuramochi, Ken-ichi; Harashima, Atsushi; Honda, Muneaki; Yamazaki, Atsushi; Nagasawa, Yuko; Yamaga, Taniichiro; Nakajima, Hiroshi

    2004-12-01

    This study examined the possible correlation between the strength of glass ionomers and their adhesive strength to bovine teeth. The shear bond strengths of three different brands of glass ionomer mixed at four different P/L ratios to bovine teeth were measured 24 hours after the cement specimens were prepared. The correlation between shear bond strength and mechanical strength reported in our previous study was also examined. No significant (p > 0.05) increases in the bond strength to bovine teeth were found in any of the cements when the mixing ratio increased. The present study showed no significant (p > 0.05) correlation between mechanical strength of cement and its bond strength to bovine teeth. Rather than trying to increase the strength of the cement, it would be more effective to enhance the adhesive bond strength through procedures such as surface conditioning or cleaning of the tooth structure when glass ionomers are used as luting agents.

  14. AirPEx: Air Pollution Exposure Model

    NARCIS (Netherlands)

    Freijer JI; Bloemen HJTh; Loos S de; Marra M; Rombout PJA; Steentjes GM; Veen MP van; LBO

    1997-01-01

    Analysis of inhalatory exposure to air pollution is an important area of investigation when assessing the risks of air pollution for human health. Inhalatory exposure research focuses on the exposure of humans to air pollutants and the entry of these pollutants into the human respiratory tract. The

  15. Air Pollution Monitoring | Air Quality Planning & Standards ...

    Science.gov (United States)

    2016-06-08

    The basic mission of the Office of Air Quality Planning and Standards is to preserve and improve the quality of our nation's air. To accomplish this, OAQPS must be able to evaluate the status of the atmosphere as compared to clean air standards and historical information.

  16. 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.

  17. 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.

  18. Strength, flexibility, and maturity in adolescent athletes.

    Science.gov (United States)

    Pratt, M

    1989-05-01

    The relationship between lower-extremity strength and flexibility and maturational status as measured by Tanner staging (TS) was assessed in 84 male high school athletes. The sum of one-repetition maximum lifts for knee extension and flexion was determined and flexibility was measured with the American Alliance of Health, Physical Education, Recreation, and Dance sit-and-reach test. Chronologic age, body weight, and percent fat were also recorded. Strength and flexibility were compared for each maturational and chronologic age category. Maturational age was better correlated with strength and flexibility than was chronologic age. All correlations were significant. Multiple regression analysis demonstrated significant correlations of TS and age with strength and flexibility. Tanner staging had greater predictive value than age for strength and flexibility. After adjusting for age, the relationship between TS and strength remained significant.

  19. Experimental knee pain reduces muscle strength

    DEFF Research Database (Denmark)

    Henriksen, Marius; Rosager, Sara; Aaboe, Jens

    2011-01-01

    Pain is the principal symptom in knee pathologies and reduced muscle strength is a common observation among knee patients. However, the relationship between knee joint pain and muscle strength remains to be clarified. This study aimed at investigating the changes in knee muscle strength following...... 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 strength was positively correlated to the pain intensity. Experimental knee pain significantly reduced knee extension...

  20. 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.

  1. Sensory source strength of used ventilation filters

    DEFF Research Database (Denmark)

    Clausen, Geo; Alm, Ole Martin; Fanger, Povl Ole

    2002-01-01

    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...

  2. Effect of oxygen content on tensile strength of polymer-derived SiC fibers

    Institute of Scientific and Technical Information of China (English)

    楚增勇; 冯春祥; 宋永才; 王应德; 李效东; 肖加余

    2002-01-01

    Air-curing is usually applied to the polymer-derived SiC fibers and, as a result, oxygen is embedded to the material. An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor fibers was established. Results also showed that oxygen content has a great influence on the mechanical properties and excellent tensile strength is usually obtained at the oxygen content of 12%~13%, similar to the density of SiC fibers. Oxygen content has a positive effect on the ceramic yield, and thus, is good to the density and tensile strength; while, oxygen content is also negative to volume content of SiC phase and crystallization of the SiC fibers, and thus, detrimental to the density and tensile strength. Both of the two effects result in the peak behavior of the tensile strength of SiC fibers.

  3. 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

  4. Strength and failure modes of ceramic multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Toftegaard, Helmuth Langmaack; Linderoth, Søren

    2012-01-01

    A model was developed for the prediction of the tensile strength of thin, symmetric 3-layer sandwich specimens. The model predictions rationalize the effect of heat-treatment temperature on the strength of sandwich specimens consisting of an YSZ (Yttria-Stabilized Zirconia) substrate coated...... and propagating into the substrate. These predictions are consistent with microstructural observations of the fracture surfaces. A good agreement was found between the measured strength values and model predictions. © 2012 Elsevier Ltd. All rights reserved....

  5. Development of a Female Atlas of Strengths

    Science.gov (United States)

    1982-02-01

    Physiotherapy ; 1977, 63(2), 51-55. 31. Falkel, .3. Planter flexor strength testing using the cybex isokinetic dynanometer. Phys. Ther.; 1978, 58(7), 847...instances "heart attacks," or "cardiac arrest," strokes ,or pulmonary embolism. If this research project causes any physical injury to you, treatment...STUDY: Edwards, R.H.T. and Hyde, S. Methods of measuring muscle strength and fatigue. Physiotherapy ; 1977, 63(2), 51-55. KEYWORDS: Muscle strength tests

  6. Strength properties of separators in alkaline solutions

    Energy Technology Data Exchange (ETDEWEB)

    Danko, T. [Viskase Corp., Chicago, IL (United States)

    1996-11-01

    Battery separator non-wovens that were coated with regenerated cellulose via the viscose process were subjected to storage in 40% potassium hydroxide (KOH) over a two month period. Samples were periodically checked for wet MD tensile strength. The test showed that among the non-wovens, the polyamide retained about 93% of its initial tensile strength whereas polyvinyl alcohol and cellulosic non-wovens retained only 55% and 35%, respectively. Adding a viscose coating to the non-wovens improved tensile strength retention by 20--25% for the polyvinyl alcohol and cellulosic materials. The viscose-coated polyamide retained more than 98% of its initial tensile strength.

  7. Correlated Strength in the Nuclear Spectral Function

    Energy Technology Data Exchange (ETDEWEB)

    D. Rohe; C. S. Armstrong; R. Asaturyan; O. K. Baker; S. Bueltmann; C. Carasco; D. Day; R. Ent; H. C. Fenker; K. Garrow; A. Gasparian; P. Gueye; M. Hauger; A. Honegger; J. Jourdan; C. E. Keppel; G. Kubon; R. Lindgren; A. Lung; D. J. Mack; J. H. Mitchell; H. Mkrtchyan; D. Mocelj; K. Normand; T. Petitjean; O. Rondon; E. Segbefia; I. Sick; S. Stepanyan; L. Tang; F. Tiefenbacher; W. F. Vulcan; G. Warren; S. A. Wood; L. Yuan; M. Zeier; H. Zhu; B. Zihlmann

    2004-10-01

    We have carried out an (e,ep) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment locates by direct measurement the correlated strength predicted by theory.

  8. Muscular strength after total hip arthroplasty

    Science.gov (United States)

    Winther, Siri B; Husby, Vigdis S; Foss, Olav A; Wik, Tina S; Svenningsen, Svein; Engdal, Monika; Haugan, Kristin; Husby, Otto S

    2016-01-01

    Background and purpose Minimizing the decrease in muscular strength after total hip arthroplasty (THA) might allow patients to recover faster. We evaluated muscular strength in patients who were operated on using 3 surgical approaches. Patients and methods In a prospective cohort study, 60 patients scheduled for primary THA were allocated to the direct lateral, posterior, or anterior approach. Leg press and abduction strength were evaluated 2 weeks or less preoperatively, 2 and 8 days postoperatively, and at 6-week and 3-month follow-up. Results Differences in maximal strength change were greatest after 2 and 8 days. The posterior and anterior approaches produced less decrease in muscular strength than the direct lateral approach. 6 weeks postoperatively, the posterior approach produced greater increase in muscular strength than the direct lateral approach, and resulted in a greater increase in abduction strength than the anterior approach. At 3-month follow-up, no statistically significant differences between the groups were found. The operated legs were 18% weaker in leg press and 15% weaker in abduction than the unoperated legs, and the results were similar between groups. Interpretation The posterior and anterior approaches appeared to have the least negative effect on abduction and leg press muscular strength in the first postoperative week; the posterior approach had the least negative effect, even up to 6 weeks postoperatively. THA patients have reduced muscle strength in the operated leg (compared to the unoperated leg) 3 months after surgery. PMID:26141371

  9. STRENGTH AND RELATED PROPERTIES OF WHITE FIR,

    Science.gov (United States)

    WOOD, PHYSICAL PROPERTIES, TREES, STRENGTH (PHYSIOLOGY), GROWTH(PHYSIOLOGY), MECHANICAL PROPERTIES, ELASTIC PROPERTIES, HARDNESS, TOUGHNESS, SHEAR STRESSES, COMPRESSIVE PROPERTIES, TABLES(DATA), CALIFORNIA, OREGON.

  10. Correlated Strength in Nuclear Spectral Function

    CERN Document Server

    Rohe, D; Asaturyan, R; Baker, O K; Bültmann, S; Carasco, C C; Day, D; Ent, R; Fenker, H C; Garrow, K; Gasparian, A; Gueye, P; Hauger, M; Honegger, A; Jourdan, J; Keppel, C E; Kubon, G; Lindgren, R; Lung, A; Mack, D J; Mitchell, J H; Mkrtchyan, H G; Mocelj, D; Normand, K; Petitjean, T; Rondon, Oscar A; Segbefia, E; Sick, I; Stepanyan, S; Tang, L; Tiefenbacher, F; Vulcan, W F; Warren, G; Wood, S A; Yuan, L; Zeier, M; Zhu, H; Zihlmann, B

    2004-01-01

    We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment confirms by direct measurement the correlated strength predicted by theory.

  11. Strength of Ship Plates under Combined Loading

    DEFF Research Database (Denmark)

    Cui, W.; Wang, Y.; Pedersen, Preben Terndrup

    2002-01-01

    Strength of ship plates plays a significant role in the ultimate strength analysis of ship structures. In recent years several authors have proposed simplified analytical methods to calculate the ultimate strength of unstiffened plates. The majority of these investigations deal with plates....... The obtained results indicate that the simplified analytical 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...

  12. 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...... 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 for practical...

  13. Procedural Options for Measuring Muscle Strength

    Directory of Open Access Journals (Sweden)

    Mindova S.

    2016-10-01

    Full Text Available The aim of the present study was to provide alternative means of measurement and evaluation of muscle strength in rehabilitation practice and diagnostics. In the last few years many electronic devices for evaluation of muscle strength have developed. Contemporary studies have shown that in addition to the standard manual muscle testing muscle strength can be assessed more objectively and analytically using electronic dynamometers and equipment. The strain gauges are used as a tool of precision in the industry that allows measurement of mechanical loads by dynamometers. By using these tools is possible to obtain continuous digital measurement and recording of muscle strength.

  14. 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…

  15. Statistical air quality mapping

    NARCIS (Netherlands)

    Kassteele, van de J.

    2006-01-01

    This thesis handles statistical mapping of air quality data. Policy makers require more and more detailed air quality information to take measures to improve air quality. Besides, researchers need detailed air quality information to assess health effects. Accurate and spatially highly resolved maps

  16. 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 t...... 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.......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...

  17. Effects of Eccentric Strength Training on Different Maximal Strength and Speed-Strength Parameters of the Lower Extremity.

    Science.gov (United States)

    Wirth, Klaus; Keiner, Michael; Szilvas, Elena; Hartmann, Hagen; Sander, Andre

    2015-07-01

    The aim of this investigation was to analyze the effects of an eccentric strength training protocol using supramaximal loads (>1 repetition maximum [1RM]) on different maximal and explosive strength parameters of the lower extremity. The eccentric maximal strength (EX max), maximal isometric strength ("maximal voluntary contraction" [MVC]), 1RM, explosive strength ("rate of force development" [RFD]), countermovement jump, and squat jump height were tested before and after a training period of 6 weeks. The training group was composed of 15 individuals with low-weight training experience and a control group of 13 subjects, also with a low-weight training experience. The lower extremities were trained 3 days per week using a 45° leg press. Each training session comprised 5 sets of 3 repetitions with a 6-minute rest between each set. The training weights were adjusted continuously during each training session and between training sessions. In each case, a load was chosen that could be lowered unilaterally in a controlled manner by the subjects. For the concentric part of the exercise, 2 investigators lifted the weight to the starting position. After 6 weeks, strength training with supramaximal loads showed a significant increase in EX max (28.2%, p strength training in the leg press generates equal and significant improvements in unilateral eccentric and bilateral eccentric-concentric maximal strength, with a nonsignificant transfer to vertical jump performances and unilateral isometric force production.

  18. Freeze-Thaw Resistance of Normal and High Strength Concretes Produced with Fly Ash and Silica Fume

    Directory of Open Access Journals (Sweden)

    Cenk Karakurt

    2015-01-01

    Full Text Available This study is based on determination of the freeze-thaw resistance of air-entrained and non-air-entrained normal strength concrete (NC and high strength concrete (HSC produced with fly ash and silica fume according to surface scaling. The procedure allows us to measure the amount of scaling per unit surface area due to a number of well defined freezing and thawing cycles in the presence of deicing salt. The weight loss, surface scaling, moisture uptake, and internal damage were measured after 0 and after every 4th freeze-thaw cycle. The test results showed that the freeze-thaw resistance is influenced directly by the compressive strength property of the concrete. Silica fume significantly reduced the resistance of normal strength concrete against freeze-thaw effect without plasticizing agent. The surface scaling of silica fume concrete without admixture was 22% higher than reference normal concrete.

  19. Understanding Bone Strength Is Not Enough.

    Science.gov (United States)

    Hernandez, Christopher J; van der Meulen, Marjolein Ch

    2017-01-09

    Increases in fracture risk beyond what are expected from bone mineral density (BMD) are often attributed to poor "bone quality," such as impaired bone tissue strength. Recent studies, however, have highlighted the importance of tissue material properties other than strength, such as fracture toughness. Here we review the concepts behind failure properties other than strength and the physical mechanisms through which they cause mechanical failure: strength describes failure from a single overload; fracture toughness describes failure from a modest load combined with a preexisting flaw or damage; and fatigue strength describes failure from thousands to millions of cycles of small loads. In bone, these distinct failure mechanisms appear to be more common in some clinical fractures than others. For example, wrist fractures are usually the result of a single overload, the failure mechanism dominated by bone strength, whereas spinal fractures are rarely the result of a single overload, implicating multiple loading cycles and increased importance of fatigue strength. The combination of tissue material properties and failure mechanisms that lead to fracture represent distinct mechanistic pathways, analogous to molecular pathways used to describe cell signaling. Understanding these distinct mechanistic pathways is necessary because some characteristics of bone tissue can increase fracture risk by impairing fracture toughness or fatigue strength without impairing bone tissue strength. Additionally, mechanistic pathways to failure associated with fracture toughness and fatigue involve multiple loading events over time, raising the possibility that a developing fracture could be detected and interrupted before overt failure of a bone. Over the past two decades there have been substantial advancements in fracture prevention by understanding bone strength and fractures caused by a single load, but if we are to improve fracture risk prevention beyond what is possible now, we must

  20. 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.

  1. Experimental Study on Deterioration Concrete Strength Different Sub-high Temperature Cycles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Tests were carried out to study the strength deterioration of concrete cooled in air or by water after sub-high temperature at different level and varying with cycles. It is proved that the cross-shaped cracks turned up and extended little by little on the surface of specimen subjected to repeat sub-high temperature, the splitting failure is characterized by cross-shaped cracks after 30 cycles, the concrete strengths decrease rapidly at early stage and to be steady subsequently with the increase of the temperature cycles,the splitting-tensile strength is more sensitive to temperature cycles than the compressive strength, the decline of concrete strength is mainly controlled by the maximum temperature having reached, the ultrasonic velocity in concrete is also declined. On the basis of test results, the mechanisms of sub-high temperature to the strength deterioration of concrete are analyzed.The formulas for calculating the compressive and splitting-tensile strength of concrete relating to the variation of temperature are proposed.

  2. 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. PMID:27555896

  3. 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.

  4. 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...... and the humidity of the room air. At a low humidity level of 30% an increased velocity could compensate for the decrease in perceived air quality due to an elevated temperature ranging from 20 °C to 26 °C. In a room with 26 °C, increased air movement was also able to compensate for an increase in humidity from 30...

  5. Influences of the Air in Metal Powder High Velocity Compaction

    Directory of Open Access Journals (Sweden)

    Liu Jun

    2017-01-01

    Full Text Available During the process of metal powder high velocity impact compaction, the air is compressed sharply and portion remains in the compacts. In order to study the Influences, a discrete density volleyball accumulation model for aluminium powder was established with the use of ABAQUS. Study found that the powder porosity air obstruct the pressing process because remaining air reduced strength and density of the compacts in the current high-speed pressing (V≤100m/s. When speed further increased (V≥100m/s, the temperature of the air increased sharply, and was even much higher than the melting point of the material. When aluminium powder was compressed at a speed of 200m/s, temperatures of air could reach 2033 K, far higher than the melting point of 877 K. Increased density of powders was a result of local softening and even melt adhesive while air between particles with high temperature and pressure flowed past.

  6. Bond strength of adhesives to dentin contaminated with smoker’s saliva

    Science.gov (United States)

    Oguri, Makoto; O’Keefe, Kathy; Dusevish, Vladimir; Spencer, Paulette; Powers, John M.; Marshall, Grayson W.

    2010-01-01

    The purpose of this study was to determine the effects of contamination with smoker’s and non-smoker’s saliva on the bond strength of resin composite to superficial dentin using different adhesive systems. The interfacial structure between the resin and dentin was evaluated for each treatment using environmental scanning electron microscopy (ESEM). Freshly extracted human molars were ground with 600-grit SiC paper to expose the superficial dentin. Adhesives [One-Up-Bond-F-Plus (OUFP) and Adper-Prompt-L-Pop (APLP)] and resin composite (TPH-Spectrum) were bonded to the dentin (n = 8/group, 180 total specimens) under five surface conditions: control (adhesive applied following manufacturers’ instructions); saliva, then 5-s air dry, then adhesive; adhesive, saliva, 5-s air dry; adhesive, saliva, 5-s water rinse, 5-s air dry (ASW group); and adhesive, saliva, 5-s water rinse, 5-s air dry, reapply adhesive (ASWA group). After storage in water at 37°C for 24 h, the specimens were debonded under tension at a speed of 0.5 mm/min. ESEM photomicrographs of the dentin/adhesive interfaces were taken. Mean bond strength ranged from 8.1 to 24.1 MPa. Fisher’s protected least significant difference (P = 0.05) intervals for critical adhesive, saliva, and surface condition differences were 1.3, 1.3, and 2.1 MPa, respectively. There were no significant differences in bond strength to dentin between contamination by smoker’s and non-smoker’s saliva, but bond strengths were significantly different between adhesive systems, with OUFP twice as strong as APLP under almost all conditions. After adhesive application and contamination with either smoker’s or nonsmoker’s saliva followed by washing and reapplication of the adhesive (ASWA group), the bond strength of both adhesive systems was the same as that of the control group. PMID:20155506

  7. 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.

  8. 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

  9. 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

  10. 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…

  11. 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...

  12. Surfactant effects on soil aggregate tensile strength

    Science.gov (United States)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  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. 49 CFR 238.215 - Rollover strength.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Rollover strength. 238.215 Section 238.215 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Equipment § 238.215 Rollover strength. (a) Each passenger car shall be designed to rest on its side and...

  15. 46 CFR 160.017-17 - Strength.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Strength. 160.017-17 Section 160.017-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Chain Ladder § 160.017-17 Strength. (a) Each chain ladder...

  16. 46 CFR 163.003-17 - Strength.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Strength. 163.003-17 Section 163.003-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL CONSTRUCTION Pilot Ladder § 163.003-17 Strength. (a) Each pilot ladder must...

  17. 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 how...

  18. Examinations of factors influencing toe grip strength.

    Science.gov (United States)

    Soma, Masayuki; Murata, Shin; Kai, Yoshihiro; Nakae, Hideyuki; Satou, Yousuke; Murata, Jun; Miyazaki, Junya

    2016-11-01

    [Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole.

  19. 46 CFR 127.420 - Strength.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Strength. 127.420 Section 127.420 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Construction of Windows, Visibility, and Operability of Coverings § 127.420 Strength. Each window or...

  20. 7 CFR 29.2555 - Strength.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strength. 29.2555 Section 29.2555 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2555 Strength. The stress a tobacco leaf...

  1. 49 CFR 238.415 - Rollover strength.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Rollover strength. 238.415 Section 238.415 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Equipment § 238.415 Rollover strength. (a) Each passenger car and power car shall be designed to rest on...

  2. 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...

  3. Deformed metals - structure, recrystallisation and strength

    DEFF Research Database (Denmark)

    Hansen, Niels; Juul Jensen, Dorte

    2011-01-01

    It is shown how new discoveries and advanced experimental techniques in the last 25 years have led to paradigm shifts in the analysis of deformation and annealing structures of metals and in the way the strength of deformed samples is related to structural parameters. This is described in three...... sections: structural evolution by grain subdivision, recovery and recrystallisation and strength-structure relationships....

  4. 14 CFR 23.627 - Fatigue strength.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fatigue strength. 23.627 Section 23.627 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Fatigue strength. The structure must be designed, as far as practicable, to avoid points of...

  5. 7 CFR 29.2303 - Strength.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strength. 29.2303 Section 29.2303 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Strength. The stress a tobacco leaf can bear without tearing. (See chart, § 29.2351.)...

  6. 46 CFR 116.1020 - Strength.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Strength. 116.1020 Section 116.1020 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE THAN 150 PASSENGERS OR WITH... Visibility § 116.1020 Strength. Each window, port hole, and its means of attachment to the hull or deck...

  7. 14 CFR 35.24 - Strength.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength. 35.24 Section 35.24 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: PROPELLERS Design and Construction § 35.24 Strength. The maximum stresses developed in...

  8. Effects of Directional Exercise on Lingual Strength

    Science.gov (United States)

    Clark, Heather M.; O'Brien, Katy; Calleja, Aimee; Corrie, Sarah Newcomb

    2009-01-01

    Purpose: To examine the application of known muscle training principles to tongue strengthening exercises and to answer the following research questions: (a) Did lingual strength increase following 9 weeks of training? (b) Did training conducted using an exercise moving the tongue in one direction result in strength changes for tongue movements in…

  9. Asymmetry of Muscle Strength in Elite Athletes

    Science.gov (United States)

    Drid, Patrik; Drapsin, Miodrag; Trivic, Tatjana; Lukac, Damir; Obadov, Slavko; Milosevic, Zoran

    2009-01-01

    "Study aim": To determine muscle strength variables in elite judoists and wrestlers since thigh muscle strength and bilaterally balanced flexor-to-extensor ratio minimise injury risk and are desirable for achieving sport successes. "Material and methods": Judoists, wrestlers and untrained subjects, 10 each, were subjected to isokinetic strength…

  10. 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...

  11. Air Safety Spinoffs

    Science.gov (United States)

    1977-01-01

    Weight saving-even a matter of a few pounds-is an important consideration in airplane design and . construction. Boeing saved 200 pounds simply by substituting a new type of compressed gas cylinder on their 747 commercial airliners. For quickly evacuating passengers in the event of a ground emergency the 747 escape chutes allow ' passengers to slide to safety from the two-story height of the cabin deck. The chutes pop out of exitways and are automatically inflated in seconds by compressed air stored in pressure vessels. Boeing's weight saving resulted from a recent changeover to a new type of pressure vessel built by Structural Composites Industries Inc. of Azusa, Cal. The company employs technology originally developed for rocket motor casings; the cylinders are constructed by winding fibers around an aluminum liner. This technique offers high strength for very low weight-in this case 60 percent less than the pressure vessels earlier used on the 747. Another contribution to improved air safety is an underwater locator device. Called the "Pinger," it uses sonar techniques to locate aircraft crashed in water-or, more specifically, to recover the flight recorder aboard the airplane. Its recovery provides clues as to what caused the accident and suggests measures to prevent similar future occurrences. Until recently, there was no way to recover flight recorders aboard aircraft lost in water crashes. The Pinger, now serving 95 percent of the airline industry, provides an answer. Key element of the Pinger system is a small, battery-powered transmitter, or homing beacon, included as part of the recorder package. For as long as 30 days, the transmitter sends out an acoustic signal from water depths up to 20,000 feet. The other element of the system is a receiver, used by search crews to home in on the transmitter's signal. Originating as a U.S. Navy project, this device was refined and further developed by NASA's Langley Research Center to retrieve submerged nose cones

  12. 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.

  13. Transitional $\\gamma$ strength in Cd isotopes

    CERN Document Server

    Larsen, A C; Bürger, A; Goriely, S; Guttormsen, M; Görgen, A; Hagen, T W; Harissopulos, S; Nyhus, H T; Renstrøm, T; Schiller, A; Siem, S; Tveten, G M; Voinov, A V; 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 evidence for some extra strength, similar to what has been previously observed for the Sn isotopes. The origin of this extra strength is unclear; it might be due to $E1$ and $M1$ transitions originating from neutron skin oscillations or the spin-flip resonance, respectively.

  14. 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...... 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 equivalent thermoelastic...

  15. Extreme strength observed in limpet teeth

    Science.gov (United States)

    Barber, Asa H.; Lu, Dun; Pugno, Nicola M.

    2015-01-01

    The teeth of limpets exploit distinctive composite nanostructures consisting of high volume fractions of reinforcing goethite nanofibres within a softer protein phase to provide mechanical integrity when rasping over rock surfaces during feeding. The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa and was independent of sample size. These observations highlight an absolute material tensile strength that is the highest recorded for a biological material, outperforming the high strength of spider silk currently considered to be the strongest natural material, and approaching values comparable to those of the strongest man-made fibres. This considerable tensile strength of limpet teeth is attributed to a high mineral volume fraction of reinforcing goethite nanofibres with diameters below a defect-controlled critical size, suggesting that natural design in limpet teeth is optimized towards theoretical strength limits. PMID:25694539

  16. Exposed Dentin: Influence of Cleaning Procedures and Simulated Pulpal Pressure on Bond Strength of a Universal Adhesive System

    Science.gov (United States)

    2017-01-01

    Purpose To compare various pre-treatments serving as cleaning procedures of dentin on the bond strength of resin composite promoted by a universal adhesive system applied either in the absence or presence of simulated pulpal pressure. Materials and Methods Prior to application of the adhesive system (Scotchbond Universal) and resin composite (Filtek Z250), ground dentin surfaces were given one of five pre-treatments either without or with simulated pulpal pressure: 1) no pre-treatment, adhesive system in “self-etch” mode, 2) phosphoric acid etching, adhesive system in “total-etch” mode, 3) polishing with pumice on prophylaxis cup, 4) air abrasion with AIR-FLOW PLUS powder, 5) air abrasion with AIR-FLOW PERIO powder; n = 20/group of pre-treatment. After storage (37°C, 100% humidity, 24 h), micro shear bond strength was measured and data analyzed with parametric ANOVA including Bonferroni-Holm correction for multiple testing followed by Student’s t tests (significance level: α = 0.05). Results The ANOVA found type of pre-treatment and simulated pulpal pressure to have no significant effect on dentin bond strength. The explorative post-hoc tests showed a negative effect of simulated pulpal pressure for phosphoric acid etching (adhesive system in “total-etch” mode; p = 0.020), but not for the other four pre-treatments (all p = 1.000). Conclusion Air abrasion with powders containing either erythritol and chlorhexidine (AIR-FLOW PLUS) or glycine (AIR-FLOW PERIO) yielded dentin bond strengths similar to no pre-treatment, phosphoric acid etching, or polishing with pumice. Simulated pulpal pressure reduced the bond strength only when the self-etch adhesive system was used in total-etch mode. PMID:28081572

  17. Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

    2011-02-20

    K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and

  18. The Character Strengths of Class Clowns

    Directory of Open Access Journals (Sweden)

    Willibald F. Ruch

    2014-09-01

    Full Text Available Class clowns traditionally were studied as a type concept and identified via sociometric procedures. In the present study a variable-centered approach was favored and class clown behaviors were studied in the context of character strengths, orientations to happiness and satisfaction with life. A sample of 672 Swiss children and adolescents filled in an 18 item self-report instrument depicting class clown behaviors. A hierarchical model of class clown behaviors was developed distinguishing a general factor and the four positively correlated dimensions of identified as a class clown, comic talent, disruptive rule-breaker, and subversive joker. Analysis of the general factor showed that class clowns were primarily male, and tended to be seen as class clowns by the teacher. Analyses of the 24 character strengths of the VIA-Youth (Park & Peterson, 2006 showed that class clowns were high in humor and leadership, and low in strengths like prudence, self-regulation, modesty, honesty, fairness, perseverance, and love of learning. An inspection of signature strengths revealed that 75% of class clowns had humor as a signature strength. Furthermore, generally class clown behaviors were shown by students indulging in a life of pleasure, but low life of engagement. The four dimensions yielded different character strengths profiles. While all dimensions of class clowns behaviors were low in temperance strengths, the factors identified as the class clown and comic talent were correlated with leadership strengths and the two negative factors (disruptive rule-breaker, subversive joker were low in other directed strengths. The disruptive rule breaking class clown was additionally low in intellectual strengths. While humor predicted life satisfaction, class clowning tended to go along with diminished satisfaction with life. It is concluded that different types of class clowns need to be kept apart and need different attention by teachers.

  19. The character strengths of class clowns.

    Science.gov (United States)

    Ruch, Willibald; Platt, Tracey; Hofmann, Jennifer

    2014-01-01

    Class clowns traditionally were studied as a type concept and identified via sociometric procedures. In the present study a variable-centered approach was favored and class clown behaviors were studied in the context of character strengths, orientations to happiness and satisfaction with life. A sample of 672 Swiss children and adolescents filled in an 18 item self-report instrument depicting class clown behaviors. A hierarchical model of class clown behaviors was developed distinguishing a general factor and the four positively correlated dimensions of "identified as a class clown," "comic talent," "disruptive rule-breaker," and "subversive joker." Analysis of the general factor showed that class clowns were primarily male, and tended to be seen as class clowns by the teacher. Analyses of the 24 character strengths of the VIA-Youth (Park and Peterson, 2006) showed that class clowns were high in humor and leadership, and low in strengths like prudence, self-regulation, modesty, honesty, fairness, perseverance, and love of learning. An inspection of signature strengths revealed that 75% of class clowns had humor as a signature strength. Furthermore, class clown behaviors were generally shown by students indulging in a life of pleasure, but low life of engagement. The four dimensions yielded different character strengths profiles. While all dimensions of class clowns behaviors were low in temperance strengths, the factors "identified as the class clown" and "comic talent" were correlated with leadership strengths and the two negative factors ("disruptive rule-breaker," "subversive joker") were low in other directed strengths. The disruptive rule breaking class clown was additionally low in intellectual strengths. While humor predicted life satisfaction, class clowning tended to go along with diminished satisfaction with life. It is concluded that different types of class clowns need to be kept apart and need different attention by teachers.

  20. Fatigue strength of welded connections made of very high strength cast and rolled steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.

    2011-01-01

    Although Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still uncommon. The main objective of the research is the determination of the fatigue strength of welded con

  1. Character Strengths and Intellectual and Developmental Disability: A Strengths-Based Approach from Positive Psychology

    Science.gov (United States)

    Niemiec, Ryan M.; Shogren, Karrie A.; Wehmeyer, Michael L.

    2017-01-01

    There has been limited focus in the disability field on assessing and intervening to promote strengths of character. However, character strengths have received significant attention in the broader field of positive psychology. This paper provides an overview of the growing science of character strengths and explores why and how character strengths…

  2. Effects of warm air-drying and spreading on resin bonding.

    Science.gov (United States)

    Galan, D; Williams, P T; Kasloff, Z

    1991-12-01

    The purpose of this study was to compare the effect on resin-to-enamel bonding produced by warm air from a hair dryer, and to correlate changes in resin bond strength with resin tag structure. Herculite-XR resin composite and Bondlite bonding resin were used. The three technique variables were the type of air used for drying, air dryer distance, and drying and spreading time. Control samples were dried and the bonding resin spread with a dental air syringe, whereas warm air from a hair dryer was used on the experimental samples. The bond strength (MPa) was determined in shear at a crosshead speed of 1 mm/min. Following bond strength evaluation, the teeth were immersed in 10% HCl for enamel dissolution and the resin tag structure was examined with the SEM. ANOVA analyses of shear bond strengths were performed. Warm air-drying and spreading for 15 seconds at 6 cm and 5 seconds at 6 cm respectively, produced statistically greater shear bond strengths (x = 20.4 +/- 4.4 MPa, P less than 0.05). The other drying time/distance combinations, including the control (x = 14.4 +/- 3.3 MPa), were not statistically different. Differences in resin tag structure were qualitatively evident under the SEM, with sharp tags produced by the warm air-drying and spreading techniques, compared to the blunt tags created by syringe air-drying and spreading. Warm air-drying and spreading significantly improved the bond strength. No apparent correlation exists between bond strength and tag length.

  3. The effect of outgassing upon the closure of cracks and the strength of lunar analogues

    Science.gov (United States)

    Mizutani, H.; Spetzler, H.; Getting, I.; Martin, R. J., III; Soga, N.

    1977-01-01

    The effect of an ultrahigh vacuum and low water vapor pressure on the stress-strain relation in rocks was studied in order to understand geologic and tectonic processes of the moon. Terrestrial basaltic rocks carefully outgassed in high vacuum provided the sample material for the compression tests reported here. The tests were conducted either under 1 atm air saturated with moisture, or under high vacuum. Results of the stress-strain determinations indicated that the dry rocks could show as much as twice the strength of the wet rocks. The data may also provide a means of reconciling the high strength and high temperature exhibited by the lunar interior.

  4. Connectable solar air collectors

    Energy Technology Data Exchange (ETDEWEB)

    Oestergaard Jensen, S.; Bosanac, M.

    2002-02-01

    The project has proved that it is possible to manufacture solar air collector panels, which in an easy way can be connected into large collector arrays with integrated ducting without loss of efficiency. The developed connectable solar air collectors are based on the use of matrix absorbers in the form of perforated metal sheets. Three interconnected solar air collectors of the above type - each with an transparent area of approx. 3 m{sup 2} - was tested and compared with parallel tests on two single solar air collectors also with a transparent area of approx. 3 m{sup 2} One of the single solar air collectors has an identical absorber as the connectable solar air collectors while the absorber of the other single solar air collector was a fibre cloth. The efficiency of the three solar air collectors proved to be almost identical in the investigated range of mass flow rates and temperature differences. The solar air collectors further proved to be very efficient - as efficient as the second most efficient solar air collectors tested in the IEA task 19 project Solar Air Systems. Some problems remain although to be solved: the pressure drop across especially the connectable solar air collectors is too high - mainly across the inlets of the solar air collectors. It should, however, be possible to considerably reduce the pressure losses with a more aerodynamic design of the inlet and outlet of the solar air collectors; The connectable solar air collectors are easy connectable but the air tightness of the connections in the present form is not good enough. As leakage leads to lower efficiencies focus should be put on making the connections more air tight without loosing the easiness in connecting the solar air collectors. As a spin off of the project a simple and easy way to determine the efficiency of solar, air collectors for pre-heating of fresh air has been validated. The simple method of determining the efficiency has with success been compared with an advance method

  5. Determination of conversion factors of kerma and fluence to ambient dose equivalent for X-rays generated between 50 kV{sub p} to 125 kV{sub p}; Determinacao dos fatores de conversao de kerma no ar e de fluencia para o equivalente de dose ambiental para raios-X gerados no intervalo de 50 kV{sub p} a 125 kV{sub p}

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Maria do Socorro

    1997-12-31

    The ambient dose equivalent was determined experimentally on the interval of energy of X ray applied in diagnostic radiology. A PMMA sphere was used to simulate the trunk human (phantom), based on the definition of the report ICRU 39. The absorbed dose in different positions in the phantom was determined using LiF-TLD 100. The X ray spectra were measured with a high-purity germanium detector (HP Ge). It was also determined the HVL and the effective energy in this energy range. The conversion coefficient of the K{sub air} and {Phi} to H{sup *}(d) were determined to 10, 50 and 60 mm deep in the PMMA sphere. The obtained values were compared with data of the literature. The maximum uncertainty obtained for the coefficients was 7.2%. All parameters were also determined to the X ray quality of the incident and transmitted beam by the patient, according to the recommendation of the standard DIN 6872. The conversion factor was calculated for those situations where the X-ray beam is transmitted by a layer and Pb and it is necessary to estimate the effective dose, as in the case of shielding project of radiology diagnosis room. (author) 51 refs., 35 figs., 15 tabs.

  6. Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

    Science.gov (United States)

    Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei

    2015-02-01

    This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

  7. Development of predictive equations for lifting strengths.

    Science.gov (United States)

    Kumar, S

    1995-10-01

    The purpose of the study was to determine relationship between lifting strengths of male and female subjects and body posture, type of lift (stoop or squat) and velocity of lift. Thirty normal young adults (18 males and 12 females) volunteered for the study. All subjects were required to perform a total of 56 tasks. Of these, 28 were stoop lifts and 28 were squat lifts. In each of the categories of stoop and squat lifts, the strengths were tested in standard posture, isokinetic (linear velocity of 500 mm/s), and isometric modes at half, three-quarters and full horizontal individual reach distances in sagittal, 30 degrees lateral and 60 degrees lateral planes. The strengths were measured using a static dynamic strength tester with a load cell and an IBM microcomputer with an A/D card. The peak and average strength values were extracted and statistically compared across conditions and gender (ANOVA). Finally a multiple regression analysis was carried out to predict strength as a function of reach, posture and velocity of lift. The ANOVA revealed a highly significant effect of gender, reach, plane and velocity (p capabilities for industrial application based on simple anthropometric and strength characteristics.

  8. 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.

  9. Bond strength of resin composite to differently conditioned amalgam.

    Science.gov (United States)

    Ozcan, M; Vallittu, P K; Huysmans, M-C; Kalk, W; Vahlberg, T

    2006-01-01

    Bulk fracture of teeth, where a part of the amalgam restoration and/or the cusp is fractured, is a common clinical problem. The aim of this study was to evaluate the effect of different surface conditioning methods on the shear bond strength of a hybrid resin composite to fresh amalgam. Amalgams (N=84) were condensed into acrylic and randomly assigned to one of the following treatments (N=6): (1) Alloy primer + opaquer, (2) Air-particle abrasion (50 micro m Al(2)O(3)) + alloy primer + opaquer, (3) Silica coating (30 micro m SiO(x)) + silanization + opaquer, (4) Opaquer + pre-impregnated continuous bidirectional E-glass fibre sheets, (5) Silica coating + silanization + fibre sheets, (6) Silica coating + silanization + opaquer + fibre sheet application. Non-conditioned amalgam surfaces were considered as control group (7). The mean surface roughness depth (R(Z)) was measured from the control group and air-abraded amalgam surfaces. The resin composite was bonded to the conditioned amalgam specimens using polyethylene molds. All specimens were tested under dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of resin composite to amalgam substrates was measured in a universal testing machine (1 mm/min). Surface roughness values for the non-conditioned control group (R(Z) approximately 0.14 micro m) and for air-particle abraded surfaces with either Al(2)O(3) or SiO(x) (R(Z) approximately 0.19 micro m and R(Z) approximately 0.16 micro m, respectively) did not show significant differences (p=0.23) (One-way ANOVA). In dry conditions, silica coating and silanization followed by fibre sheet application exhibited significantly higher results (14.8+/-5.6 MPa) than those of the groups conditioned with alloy primer (2.2+/-0.7 MPa) (p<0.001), air-particle abrasion+alloy primer (4.4+/-2.0 MPa, p<0.001), silica coating+silanization alone (6.2+/-0.8 MPa, p=0.009) or non-conditioned group (1.4+/-0.6, p<0.001). Silica coating and silanization followed

  10. 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.

  11. Are only Emotional Strengths Emotional? Character Strengths and Disposition to Positive Emotions.

    Science.gov (United States)

    Güsewell, Angelika; Ruch, Willibald

    2012-07-01

    This study aimed to examine the relations between character strengths and dispositional positive emotions (i.e. joy, contentment, pride, love, compassion, amusement, and awe). A sample of 574 German-speaking adults filled in the Dispositional Positive Emotion Scales (DPES; Shiota, Keltner, & John, 2006), and the Values in Action Inventory of Strengths (VIA-IS; Peterson, Park, & Seligman, 2005). The factorial structure of the DPES was examined on item level. Joy and contentment could not be clearly separated; the items of the other five emotions loaded on separate factors. A confirmatory factor analysis assuming two latent factors (self-oriented and object/situation specific) was computed on scale level. Results confirmed the existence of these factors, but also indicated that the seven emotions did not split up into two clearly separable families. Correlations between dispositional positive emotions and character strengths were positive and generally low to moderate; a few theoretically meaningful strengths-emotions pairs yielded coefficients>.40. Finally, the link between five character strengths factors (i.e. emotional strengths, interpersonal strengths, strengths of restraint, intellectual strengths, and theological strengths) and the emotional dispositions was examined. Each of the factors displayed a distinctive "emotional pattern"; emotional strengths evidenced the most numerous and strongest links to emotional dispositions.

  12. 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.

  13. Strength of Concrete Containing Basalt Fibre

    OpenAIRE

    2015-01-01

    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 be...

  14. Adhesion Strength of Biomass Ash Deposits

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Jensen, Peter Arendt; Wu, Hao

    2015-01-01

    This study investigates the shear adhesion strength of biomass ash deposits on superheater tubes. Artificial biomass ash deposits were prepared on superheater tubes and sintered in an oven at temperatures up to 1000°C. Subsequently, the deposits were sheared off with the help of an electrically...... controlled arm. Higher sintering temperatures resulted in greater adhesion strengths, with a sharp increase observed near the melting point of the ash. Repetition of experiments with fixed operation conditions revealed considerable variation in the obtained adhesion strengths, portraying the stochastic...

  15. Adhesion Strength of Biomass Ash Deposits

    DEFF Research Database (Denmark)

    Laxminarayan, Yashasvi; Jensen, Peter Arendt; Wu, Hao

    2016-01-01

    . Therefore, timely removal of ash deposits is essential for optimal boiler operation. In order to improve the qualitative and quantitative understanding of deposit shedding in boilers, this study investigates the shear adhesion strength of biomass ash deposits on superheater tubes. Artificial biomass ash...... deposits were prepared on superheater tubes and sintered in an oven at temperatures up to 1000 °C. Subsequently, the deposits were sheared off by an electrically controlled arm, and the corresponding adhesion strength was measured. The results reveal the effect of temperature, ash/deposit composition......, sintering duration, and steel type on the adhesion strength....

  16. 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...

  17. 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.

  18. AirCompare

    Data.gov (United States)

    U.S. Environmental Protection Agency — AirCompare contains air quality information that allows a user to compare conditions in different localities over time and compare conditions in the same location...

  19. 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 before...

  20. 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 facilities...

  1. 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 ...

  2. 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...

  3. 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.

  4. Air Power and Warfare

    Science.gov (United States)

    1978-09-01

    Memorial, 1963. (T) 767.8 A3 ser .3, V.4) Air war against Germany and Italy, 1939-1943. Canberra: Australian War Memorial, 1954. (D 767.8 A3 Ser .3, V.3...et al. Air poder indivisible Air University Ouarterly Review 2:5-18, Fall 1950. Spaatz, Crrl. Air-power odds against us. Readers Digest 58:11-14, June

  5. 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...... as idenfiying "good practices" to reduce health impact of indoor air exposure and suggest areas for future improvements....

  6. Testing of environmental radiation monitors using the Risø low-level radiation measurement stations

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.

    2000-01-01

    a simulation of a radioactive plume passing over the monitors during a certain time was made using a specially designed source set up in the field that was able to vary the air kerma rate from low activity Cs-137 sources additional to the natural air kerma rate. It is demonstrated that a typical environmental...... radiation detector can distinguish an increase of the ambient air kerma rate of less than 3%....

  7. 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.

  8. 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.…

  9. Experimental Study on Coal-Breaking Pressure for Compressed Air

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on lab model experiments and through the limit analysis, the theoretical formula of calculauoncoal-breaking pressure with compressed air was derived. The experimental result shows that blasting pressure mustexceed 84.0 MPa to break coal with compressive strength of 13.2 MPa. The research provides an important theoretical basis for the design of airshooting mining and industrial tests.

  10. 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.

  11. 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.

  12. 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.

  13. FPSO Global Strength and Hull Optimization

    Institute of Scientific and Technical Information of China (English)

    Junyuan Ma; Jianhua Xiao; Rui Ma; Kai Cao

    2014-01-01

    Global strength is a significant item for floating production storage and offloading (FPSO) design, and steel weight plays an important role in the building costs of FPSO. It is the main task to consider and combine these two aspects by optimizing hull dimensions. There are many optional methods for the global strength analysis. A common method is to use the ABS FPSO Eagle software to analyze the global strength including the rule check and direct strength analysis. And the same method can be adopted for the FPSO hull optimization by changing the depth. After calculation and optimization, the results are compared and analyzed. The results can be used as a reference for the future design or quotation purpose.

  14. Bundled Hybrid Offset Riser Global Strength Analysis

    Institute of Scientific and Technical Information of China (English)

    William C.Webster; Zhuang Kang; Wenzhou Liang; Youwei Kang; Liping Sun

    2011-01-01

    Bundled hybrid offset riser(BHOR)global strength analysis,which is more complex than single line offset riser global strength analysis,was carried out in this paper.At first,the equivalent theory is used to deal with BHOR,and then its global strength in manifold cases was analyzed,along with the use of a three-dimensional nonlinear time domain finite element program.So the max bending stress,max circumferential stress,and max axial stress in the BHOR bundle main section(BMS)were obtained,and the values of these three stresses in each riser were obtained through the "stress distribution method".Finally,the Max Von Mises stress in each riser was given and a check was made whether or not they met the demand.This paper provides a reference for strength analysis of the bundled hybrid offset riser and some other bundled pipelines.

  15. 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.

  16. 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. 

  17. 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

  18. 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)..

  19. Strengths-based Practice and Motivational Interviewing

    Directory of Open Access Journals (Sweden)

    Trevor Jay Manthey

    2011-09-01

    Full Text Available There has been recent concern that many practices and programs erroneously claim to be strengths-based. In reaction some have called for researchers to make systematic comparisons to the tenets of strengths-based practice (SBP before making the contention that an intervention is strengths-based. Motivational interviewing (MI is an intervention which has been described as being strengths-based; however, no systematic efforts have yet been made to compare the two. This article takes a methodical approach to comparing SBP and MI to determine level of cohesion and how they might be used together. A case-example is used to illustrate how MI and SBP may be used in conjunction and implications for social work practice and education are discussed.

  20. Agile Software Methodologies: Strength and Weakness

    OpenAIRE

    Dr. Adel Hamdan Mohammad; Dr. Tariq Alwada’n; Dr. Jafar "M.Ali" Ababneh

    2013-01-01

    Agile methodologies are great software development methodologies. No doubt that these methodologies have widespread reputation. The core of agile methodologies is people. Customer and each team member in agiledevelopment teams are the key success or failure factor in agile process. In this paper authors demonstrate strength and weakness points in agile methodologies. Also authors demonstrate how strength and weakness factors can affect the overall results of agile development process.

  1. E1 strength in N = 82 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, T.; Volz, S.; Babilon, M.; Mohr, P.; Vogt, K.; Zilges, A

    2003-05-19

    Recently the importance of small contributions of electric dipole strength near the particle threshold to the production rates of atomic nuclei has become evident. Prior estimates concentrated on the Giant Dipole Resonance (GDR) which dominates photoabsorption in all nuclei. Extrapolations to smaller excitation energies were assumed to be sufficiently reliable. However, new measurements reveal that collective E1 strength can be found in the threshold region.

  2. Cadmium Alternatives for High-Strength Steel

    Science.gov (United States)

    2011-09-22

    191 19b. TELEPHONE NUMBER (include area code) 301 -342-8101 iii Table of Contents Note that original JTP section numbers are preceded by...specified. The focus of this JTP is on high-strength structural alloy steels used for various applications. Alloy AISI 4130 was used for adhesion and...NaCl) solution under constant amplitude loading to determine fatigue life using hourglass specimens prepared from high strength AISI 4340 steel. The

  3. High-Hot-Strength Ceramic Fibers

    Science.gov (United States)

    Sayir, Ali; Matson, Lawrence E.

    1994-01-01

    Continuous fibers consisting of laminae of alumina and yttrium aluminum garnet offer exceptionally high strength, resistance to creep, and chemical stability at high temperatures. These fibers exceed tensile strength of sapphire fibers. Leading candidates for reinforcement of intermetallic-matrix composites in exhaust nozzles of developmental high-speed civil transport aircraft engines. Other applications are in aerospace, automotive, chemical-process, and power-generation industries.

  4. Hydrogen degradation of high strength weldable steels

    OpenAIRE

    J. Ćwiek

    2007-01-01

    Purpose: Purpose of this paper is presentation of hydrogen degradation issue of high strength steels andespecially their welded joints. Establishing of applicable mechanisms of hydrogen-enhanced cracking was theaim of performed research.Design/methodology/approach: High strength quenched and tempered steels grade S690Q were used. Weldedjoints were prepared with typical technology used in shipyards. Susceptibility to hydrogen degradation in seawater under cathodic polarization was evaluated wi...

  5. 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

  6. How to Scale Down Postsynaptic Strength

    OpenAIRE

    2013-01-01

    Synaptic scaling is a form of synaptic plasticity that contributes to the homeostatic regulation of neuronal activity both in vitro and in vivo, by bidirectionally and proportionally adjusting postsynaptic AMPA receptor (AMPAR) abundance to compensate for chronic perturbations in activity. This proportional regulation of synaptic strength allows synaptic scaling to normalize activity without disrupting the synapse-specific differences in strength thought to underlie memory storage, but how su...

  7. Collagen fibril diameter and leather strength.

    Science.gov (United States)

    Wells, Hannah C; Edmonds, Richard L; Kirby, Nigel; Hawley, Adrian; Mudie, Stephen T; Haverkamp, Richard G

    2013-11-27

    The main structural component of leather and skin is type I collagen in the form of strong fibrils. Strength is an important property of leather, and the way in which collagen contributes to the strength is not fully understood. Synchrotron-based small angle X-ray scattering (SAXS) is used to measure the collagen fibril diameter of leather from a range of animals, including sheep and cattle, that had a range of tear strengths. SAXS data were fit to a cylinder model. The collagen fibril diameter and tear strength were found to be correlated in bovine leather (r(2) = 0.59; P = 0.009), with stronger leather having thicker fibrils. There was no correlation between orientation index, i.e., fibril alignment, and fibril diameter for this data set. Ovine leather showed no correlation between tear strength and fibril diameter, nor was there a correlation across a selection of other animal leathers. The findings presented here suggest that there may be a different structural motif in skin compared with tendon, particularly ovine skin or leather, in which the diameter of the individual fibrils contributes less to strength than fibril alignment does.

  8. 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.

  9. DYNAMIC EFFECTIVE SHEAR STRENGTH OF SATURATED SAND

    Institute of Scientific and Technical Information of China (English)

    邵生俊; 谢定义

    2002-01-01

    The dynamic effective shear strength of saturated sand under cyclic loading is discussed in this paper. The discussion includes the transient time dependency behaviors based on the analysis of the results obtained in conventional cyclic triaxial tests and cyclic torsional shear triaxial tests. It has been found that the dynamic effective shear strength is composed of effective frictional resistance and viscous resistance, which are characterized by the strain rate dependent feature of strength magnitude, the coupling of consolidation stress with cyclic stress and the dependency of time needed to make the soil strength suffciently mobilized, and can also be expressed by the extended Mohr-Coulomb's law. The two strength parameters of the dynamic effective internal frictional angle φd and the dynamic viscosity coefficient η are determined. The former is unvaried for different number of cyclic loading, dynamic stress form and consolidation stress ratio. And the later is unvaried for the different dynamic shear strain rate γt developed during the sand liquefaction, but increases with the increase of initial density of sand. The generalization of dynamic effective stress strength criterion in the 3-dimensional effective stress space is studied in detail for the purpose of its practical use.

  10. Mapping strengths into virtues: The relation of the 24 VIA-strengths to six ubiquitous virtues

    Directory of Open Access Journals (Sweden)

    Willibald eRuch

    2015-04-01

    Full Text Available The Values-in-Action (VIA-classification distinguishes six core virtues and 24 strengths. As the assignment of the strengths to the virtues was done on theoretical grounds it still needs empirical verification. As an alternative to factor analytic investigations the present study utilizes expert judgments. In a pilot study the conceptual overlap among five sources of knowledge (strength’s name including synonyms, short definitions, brief descriptions, longer theoretical elaborations, and item content about a particular strength was examined. The results show that the five sources converged quite well, with the short definitions and the items being slightly different from the other. All strengths exceeded a cut-off value but the convergence was much better for some strengths (e.g., zest than for others (e.g., perspective. In the main study 70 experts (from psychology, philosophy, theology, etc. and 41 laypersons rated how prototypical the strengths are for each of the six virtues. The results showed that 10 were very good markers for their virtues, 9 were good markers, four were acceptable markers, and only one strength failed to reach the cut-off score for its assigned virtue. However, strengths were often markers for two or even three virtues, and occasionally they marked the other virtue more strongly than the one they were assigned to. The virtue prototypicality ratings were slightly positively correlated with higher coefficients being found for justice and humanity. A factor analysis of the 24 strengths across the ratings yielded the six factors with an only slightly different composition of strengths and double loadings. It is proposed to adjust either the classification (by reassigning strengths and by allowing strengths to be subsumed under more than one virtue or to change the definition of certain strengths so that they only exemplify one virtue. The results are discussed in the context of factor analytic attempts to verify the

  11. Establishment of a primary standard system for low energy X-rays using a free air ionization chamber; Estabelecimento de um sistema padrao primario para raios-X de energias baixas com uma camara de ionizacao de ar livre

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Natalia Fiorini da

    2016-08-01

    In this work a primary standard system was established for low energy X-rays (10 kV to 50 kV), using a free air ionization chamber with concentric cylinders, Victoreen (Model 481-5), at the Calibration Laboratory of Instruments (LCI) of the Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP). For this, a new ionization chamber alignment protocol was developed for the radiation system and a modification on the micrometer housing used for the movement of the internal cylinders was ma de. The results obtained for the stability and characterization tests showed to be within the limits established by the standards IEC 61674 and IEC 60731. The correction factors for photon attenuation in the air, transmission and scattering in the diaphragm, scattering and fluorescence and ion recombination were also determined. These values were compared with those obtained by the German primary standard laboratory, Physikalisch-Technische Bundesanstalt (PTB), showing good agreement. Finally, the absolute values of the quantity air kerma rate for the standard qualities direct beams MWV28 and WMV35 and the attenuated beams WMH28 and WMH35 were determined; the results are in agreement, with a maximum difference of 3,8% with the values obtained using the secondary standard system of LCI. (author)

  12. 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....

  13. Silanated Surface Treatment: Effects on the Bond Strength to Lithium Disilicate Glass-Ceramic.

    Science.gov (United States)

    Baratto, Samantha Schaffer Pugsley; Spina, Denis Roberto Falcão; Gonzaga, Carla Castiglia; Cunha, Leonardo Fernandes da; Furuse, Adilson Yoshio; Baratto Filho, Flares; Correr, Gisele Maria

    2015-10-01

    The aim of this study was to evaluate the effect of silanization protocols on the bond strength of two resin cements to a lithium disilicate glass-ceramic. Thirty-two ceramic discs were assigned to 2 groups (n=16): G1 - dual-cured resin cement and G2 - light-cured resin cement. Four subgroups were evaluated according to the used silanization protocol. The glass-ceramic was etched with 10% hydrofluoric acid for 20 s and silane was applied for 1 min, as follows: CTL - according to the manufacturer's instructions; HA - dried with hot air; NWA - washed and dried with water and air at room temperature; HWA - washed and dried with hot water and hot air. Thereafter, adhesive was applied and light-cured for 20 s. Silicon molds were used to prepare resin cement cylinders (1x1 mm) on the ceramic surface. The specimens were stored in deionized water at 37 °C for 48 h and subjected to a micro-shear test. The data were submitted to statistical analysis (?#61537;=0.05). Group G1 showed higher bond strengths than G2, except for the CTL and NWA subgroups. Differences as function of the silanization protocol were only observed in G1: HWA (25.13±6.83)≥HA (22.95±7.78)≥CTL(17.44±7.24) ≥NWA(14.63±8.76). For G2 there was no difference among the subgroups. In conclusion, the silanization protocol affected the resin cement/ceramic bond strengths, depending on the material. Washing/drying with hot water and/or hot air increased only the bond strength of the dual-cured resin cement.

  14. Dispersion and Reinforcement of Nanotubes in High Temperature Polymers for Ultrahigh Strength and Thermally Conductive Nanocomposites

    Science.gov (United States)

    2007-10-03

    SWNT [35,36], polypropylene/nano-carbon fiber , polystyrene (PS)/MWNT [34,43] and in-situ polymerization of PI/SWNT [38]) in polymer matrices to...strength and thermal/electric conductivity based on soft macromolecules of controlled glass transition temperature. 1.4.1 The Polybenzoxazoles (PBO...around 270 GPa, greater than that of steel fibers . PBO had been developed by US Air Force researchers as a super heat resistant polymer that surpasses

  15. 30 CFR 56.19021 - Minimum rope strength.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Minimum rope strength. 56.19021 Section 56... Wire Ropes § 56.19021 Minimum rope strength. At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength...

  16. 30 CFR 75.1431 - Minimum rope strength.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Minimum rope strength. 75.1431 Section 75.1431... strength. At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength values obtained by the following formulas...

  17. 30 CFR 77.1431 - Minimum rope strength.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Minimum rope strength. 77.1431 Section 77.1431... Hoisting Wire Ropes § 77.1431 Minimum rope strength. At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength...

  18. 30 CFR 57.19021 - Minimum rope strength.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Minimum rope strength. 57.19021 Section 57... Hoisting Wire Ropes § 57.19021 Minimum rope strength. At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength...

  19. 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)

  20. Impaired tongue strength and endurance in developmental verbal dyspraxia: a physiological analysis.

    Science.gov (United States)

    Murdoch, B E; Attard, M D; Ozanne, A E; Stokes, P D

    1995-01-01

    Tongue strength and endurance measures were obtained from six children with developmental verbal dyspraxia (DVD) aged between 5;6 years and 11;5 years and compared to those achieved by six normal speaking controls matched for age and sex. The instrument for measuring tongue strength comprised an air-filled soft rubber bulb connected to a pressure transducer. The results indicated that the DVD group had weaker lingual musculature than the controls. In addition the DVD subjects exhibited significantly reduced tongue strength endurance compared with the controls. Overall the findings support the hypothesis that a motor impairment forms at least part of the basis of DVD and may be indicative of the presence of a concomitant dysarthria in children with DVD, or may reflect an underspecification of the motor programme. The need for revision of contemporary taxonomies relating to childhood motor speech disorders is discussed.

  1. Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Reed, J. L., E-mail: jlreed2@wisc.edu; Micka, J. A.; Culberson, W. S.; DeWerd, L. A. [Department of Medical Physics, University of Wisconsin–Madison, Madison, Wisconsin 53705 (United States); Rasmussen, B. E. [Department of Radiation Oncology, UP Health System Marquette, 580 West College Avenue, Marquette, Michigan 49855 (United States); Davis, S. D. [Department of Medical Physics, McGill University Health Centre, Montreal General Hospital (L5-112), 1650 Cedar Avenue, Montreal, Quebec H3G 1A4 (Canada)

    2014-12-15

    Purpose: To determine the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters (TLD-100) for {sup 125}I and {sup 103}Pd brachytherapy sources relative to {sup 60}Co. Methods: LiF:Mg,Ti TLDs were irradiated with low-energy brachytherapy sources and with a {sup 60}Co teletherapy source. The brachytherapy sources measured were the Best 2301 {sup 125}I seed, the OncoSeed 6711 {sup 125}I seed, and the Best 2335 {sup 103}Pd seed. The TLD light output per measured air-kerma strength was determined for the brachytherapy source irradiations, and the TLD light output per air kerma was determined for the {sup 60}Co irradiations. Monte Carlo (MC) simulations were used to calculate the dose-to-TLD rate per air-kerma strength for the brachytherapy source irradiations and the dose to TLD per air kerma for the {sup 60}Co irradiations. The measured and MC-calculated results for all irradiations were used to determine the TLD intrinsic energy dependence for {sup 125}I and {sup 103}Pd relative to {sup 60}Co. Results: The relative TLD intrinsic energy dependences (relative to {sup 60}Co) and associated uncertainties (k = 1) were determined to be 0.883 ± 1.3%, 0.870 ± 1.4%, and 0.871 ± 1.5% for the Best 2301 seed, OncoSeed 6711 seed, and Best 2335 seed, respectively. Conclusions: The intrinsic energy dependence of TLD-100 is dependent on photon energy, exhibiting changes of 13%–15% for {sup 125}I and {sup 103}Pd sources relative to {sup 60}Co. TLD measurements of absolute dose around {sup 125}I and {sup 103}Pd brachytherapy sources should explicitly account for the relative TLD intrinsic energy dependence in order to improve dosimetric accuracy.

  2. Influence of curing regimes on compressive strength of ultra high performance concrete

    Indian Academy of Sciences (India)

    Prabhat Ranjan Prem; B H Bharatkumar; Nagesh R Iyer

    2013-12-01

    The present paper is aimed to identify an efficient curing regime for ultra high performance concrete (UHPC), to achieve a target compressive strength more than 150 MPa, using indigenous materials. The thermal regime plays a vital role due to the limited fineness of ingredients and low water/binder ratio. By activation of the reaction kinetics, the effectiveness of the binder is enhanced which leads to improvements in mechanical as well as durability properties. The curing cycle employed are ambient air curing, water curing and hot air curing. The specimens were exposed to thermal regime at (90°C/150°C/200°C) for duration of 24, 48 or 72 hours at the age of 3rd and 7th day followed with air curing or water curing till 28 days. The results showed a marked difference in compressive strength ranging from 217 to 142 MPa with change in curing regimes. The samples when thermally cured at the age of 3rd and 7th day produced an average ultimate strength of 217–152 MPa and 196–150 MPa, respectively.

  3. 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.

  4. 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.

  5. Prediction of 28-day Compressive Strength of Concrete from Early Strength and Accelerated Curing Parameters

    OpenAIRE

    T.R. Neelakantan; S. Ramasundaram; Shanmugavel, R.; R. Vinoth

    2013-01-01

    Predicting 28-day compressive strength of concrete is an important research task for many years. In this study, concrete specimens were cured in two phases, initially at room temperature for a maximum of 30 h and later at a higher temperature for accelerated curing for a maximum of 3 h. Using the early strength obtained after the two-phase curing and the curing parameters, regression equations were developed to predict the 28-day compressive strength. For the accelerated curing (higher temper...

  6. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    Directory of Open Access Journals (Sweden)

    Naomi Tanoue

    2013-07-01

    Full Text Available OBJECTIVE: The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. MATERIAL AND METHODS: Disk specimens (diameter 10 mm and thickness 2.5 mm were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1 air-abraded with 50-70-µm grain alumina (CON; 2 1 + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA; 3 1 + conditioned with a primer including a diphosphate monomer (MDP; 4 treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. RESULTS: The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05 greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. CONCLUSION: Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.

  7. Strength analysis of laser welded lap joint for ultra high strength steel

    Science.gov (United States)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  8. RING-TENSILE-STRENGTH AND FLEXURE-STRENGTH CORRELATIONS OF SEA ICE.

    Science.gov (United States)

    SEA ICE, MECHANICAL PROPERTIES), TENSILE PROPERTIES, SALINITY, TEMPERATURE, ICE, FLEXURAL STRENGTH , CORRELATION TECHNIQUES, ACCURACY, SAMPLING, THICKNESS, PREDICTIONS, ANTARCTIC REGIONS, LOADS(FORCES)

  9. 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.

  10. Corticospinal adaptations and strength maintenance in the immobilized arm following 3 weeks unilateral strength training.

    Science.gov (United States)

    Pearce, A J; Hendy, A; Bowen, W A; Kidgell, D J

    2013-12-01

    Cross-education strength training has being shown to retain strength and muscle thickness in the immobilized contralateral limb. Corticospinal mechanisms have been proposed to underpin this phenomenon; however, no transcranial magnetic stimulation (TMS) data has yet been presented. This study used TMS to measure corticospinal responses following 3 weeks of unilateral arm training on the contralateral, immobilize arm. Participants (n = 28) were randomly divided into either immobilized strength training (Immob + train) immobilized no training (Immob) or control. Participants in the immobilized groups had their nondominant arm rested in a sling, 15 h/day for 3 weeks. The Immob + train group completed unilateral arm curl strength training, while the Immob and control groups did not undertake training. All participants were tested for corticospinal excitability, strength, and muscle thickness of both arms. Immobilization resulted in a group x time significant reduction in strength, muscle thickness and corticospinal excitability for the untrained limb of the Immob group. Conversely, no significant change in strength, muscle thickness, or corticospinal excitability occurred in the untrained limb of the Immob + train group. These results provide the first evidence of corticospinal mechanisms, assessed by TMS, underpinning the use of unilateral strength training to retain strength and muscle thickness following immobilization of the contralateral limb.

  11. Air filtration in HVAC systems

    CERN Document Server

    Ginestet, Alain; Tronville, Paolo; Hyttinen, Marko

    2010-01-01

    Air filtration Guidebook will help the designer and user to understand the background and criteria for air filtration, how to select air filters and avoid problems associated with hygienic and other conditions at operation of air filters. The selection of air filters is based on external conditions such as levels of existing pollutants, indoor air quality and energy efficiency requirements.

  12. The TOMPs ambient air monitoring network - Continuous data on UK air quality for over 20 years.

    Science.gov (United States)

    Graf, Carola; Katsoyiannis, Athanasios; Jones, Kevin C; Sweetman, Andrew J

    2016-10-01

    Long-term air monitoring datasets are needed for persistent organic pollutants (POPs) to assess the effectiveness of source abatement measures and the factors controlling ambient levels. The Toxic Organic Micro Pollutants (TOMPs) Network, which has operated since 1991, collects ambient air samples at six sites across England and Scotland, using high-volume active air samplers. The network provides long-term ambient air trend data for a range of POPs at both urban and rural locations. Data from the network provides the UK Government, regulators and researchers with valuable information on emission/source controls and on the effectiveness of international chemicals regulation such as the Stockholm Convention and UN/ECE Protocol on POPs. The target chemicals of TOMPs have been polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and, since 2010, polybrominated diphenyl ethers (PBDEs). The continuous monitoring of these compounds demonstrates the constant decline in UK air concentrations over the last two decades, with average clearance rates for PCDD/Fs in urban locations of 5.1 years and for PCBs across all sites 6.6 years. No significant declines in rural locations for PCDD/Fs have been observed. There is a strong observable link between the declining ambient air concentrations and the emission reductions estimated in the annually produced National Atmospheric Emission Inventory (NAEI) dataset. These findings clearly demonstrate the unique strengths of long-term consistent datasets for the evaluation of the success of chemical regulation and control.

  13. Magnetic Field Strengths in Photodissociation Regions

    CERN Document Server

    Balser, Dana S; Jeyakumar, S; Bania, T M; Montet, Benjamin T; Shitanishi, J A

    2015-01-01

    We measure carbon radio recombination line (RRL) emission at 5.3 GHz toward four HII regions with the Green Bank Telescope (GBT) to determine the magnetic field strength in the photodissociation region (PDR) that surrounds the ionized gas. Roshi (2007) suggests that the non-thermal line widths of carbon RRLs from PDRs are predominantly due to magneto-hydrodynamic (MHD) waves, thus allowing the magnetic field strength to be derived. We model the PDR with a simple geometry and perform the non-LTE radiative transfer of the carbon RRL emission to solve for the PDR physical properties. Using the PDR mass density from these models and the carbon RRL non-thermal line width we estimate total magnetic field strengths of B ~ 100-300 micro Gauss in W3 and NGC6334A. Our results for W49 and NGC6334D are less well constrained with total magnetic field strengths between B ~ 200-1000 micro Gauss. HI and OH Zeeman measurements of the line-of-sight magnetic field strength (B_los), taken from the literature, are between a facto...

  14. Neuromuscular adaptations following prepubescent strength training.

    Science.gov (United States)

    Ozmun, J C; Mikesky, A E; Surburg, P R

    1994-04-01

    Underlying mechanisms of prepubescent strength gains following resistance training are speculative. The purpose of this investigation was to determine the effects of 8 wk of resistance training on muscular strength, integrated EMG amplitude (IEMG), and arm anthropometrics of prepubescent youth. Sixteen subjects (8 males, 8 females) were randomly assigned to trained or control groups. All subjects (mean age = 10.3 yr) were of prepubertal status according to the criteria of Tanner. The trained group performed three sets (7-11 repetitions) of bicep curls with dumbbells three times per week for 8 wk. Pre- and posttraining measurements included isotonic and isokinetic strength of the elbow flexors, arm anthropometrics, and IEMG of the biceps brachii. Planned comparisons for a 2 x 2 (group by test) ANOVA model were used for data analysis. Significant isotonic (22.6%) and isokinetic (27.8%) strength gains were observed in the trained group without corresponding changes in arm circumference or skinfolds. The IEMG amplitude increased 16.8% (P < 0.05). The control group did not demonstrate any significant changes in the parameters measured. Early gains in muscular strength resulting from resistance training prepubescent children may be attributed to increased muscle activation.

  15. Humidity effects on wire insulation breakdown strength.

    Energy Technology Data Exchange (ETDEWEB)

    Appelhans, Leah

    2013-08-01

    Methods for the testing of the dielectric breakdown strength of insulation on metal wires under variable humidity conditions were developed. Two methods, an ASTM method and the twisted pair method, were compared to determine if the twisted pair method could be used for determination of breakdown strength under variable humidity conditions. It was concluded that, although there were small differences in outcomes between the two testing methods, the non-standard method (twisted pair) would be appropriate to use for further testing of the effects of humidity on breakdown performance. The dielectric breakdown strength of 34G copper wire insulated with double layer Poly-Thermaleze/Polyamide-imide insulation was measured using the twisted pair method under a variety of relative humidity (RH) conditions and exposure times. Humidity at 50% RH and below was not found to affect the dielectric breakdown strength. At 80% RH the dielectric breakdown strength was significantly diminished. No effect for exposure time up to 140 hours was observed at 50 or 80%RH.

  16. Strength and Fractography of Glass Wool Fibres

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

    strength. In spite of those advantages, GWFs show a certain degree of brittleness, which limits the mechanical performance of GWFs during both transportation and application. Therefore, a reduction in the brittleness of GWFs is an inevitable task for us. To do so, it is important to look into the fracture...... behaviour and its connection to the mechanical strength. Here we report a detailed study of fracture behaviour of GWFs by means of uniaxial tensile strength and SEM micrographs of fractured surfaces. The tensile strength data of GWFs are evaluated by Weibull statistics. The Weibull model does not take...... between fracture strength (sf) and mirror radius (r), i.e., sf = A*r, is confirmed for all the GWFs studied. The materials constant, A, (mirror constant) is found to be 2.4 ~ 2.7 MPam½ for basaltic wool and 2.0 MPam½ for E-glass wool, which is similar to the value reported in the literature for different...

  17. How to scale down postsynaptic strength.

    Science.gov (United States)

    Tatavarty, Vedakumar; Sun, Qian; Turrigiano, Gina G

    2013-08-07

    Synaptic scaling is a form of synaptic plasticity that contributes to the homeostatic regulation of neuronal activity both in vitro and in vivo, by bidirectionally and proportionally adjusting postsynaptic AMPA receptor (AMPAR) abundance to compensate for chronic perturbations in activity. This proportional regulation of synaptic strength allows synaptic scaling to normalize activity without disrupting the synapse-specific differences in strength thought to underlie memory storage, but how such proportional scaling of synaptic strength is accomplished at the biophysical level is unknown. Here we addressed this question in cultured rat visual cortical pyramidal neurons. We used photoactivation and fluorescence recovery after photobleaching of fluorescently tagged AMPAR to show that scaling down, but not up, decreases the steady-state accumulation of synaptic AMPAR by increasing the rate at which they unbind from and exit the postsynaptic density (Koff). This increase in Koff was not diffusion limited, was independent of AMPAR endocytosis, and was prevented by a scaffold manipulation that specifically blocks scaling down, suggesting that it is accomplished through enhanced dissociation of AMPAR from synaptic scaffold tethers. Finally, simulations show that increasing Koff decreases synaptic strength multiplicatively, by reducing the fractional occupancy of available scaffold "slots." These data demonstrate that scaling down is accomplished through a regulated increase in Koff, which in turn reduces the fractional occupancy of synaptic scaffolds to proportionally reduce synaptic strength.

  18. BEHAVIOR OF AIR-ENTRAINED CONCRETE AFTER FREEZE-THAW CYCLES

    Institute of Scientific and Technical Information of China (English)

    Huaishuai Shang; Yupu Song; Jinping Ou

    2009-01-01

    The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in northern cold regions.

  19. CHARACTERIZATION OF TENSILE STRENGTH OF GLOVEBOX GLOVES

    Energy Technology Data Exchange (ETDEWEB)

    Korinko, P.; Chapman, G.

    2012-02-29

    A task was undertaken to compare various properties of different glovebox gloves, having various compositions, for use in gloveboxes at the Savannah River Site (SRS). One aspect of this project was to determine the tensile strength (TS) of the gloves. Longitudinal tensile samples were cut from 15 different gloves and tensile tested. The stress, load, and elongation at failure were determined. All of the gloves that are approved for glovebox use and listed in the glovebox procurement specification met the tensile and elongation requirements. The Viton{reg_sign} compound gloves are not listed in the specification, but exhibited lower tensile strengths than permissible based on the Butyl rubber requirements. Piercan Polyurethane gloves were the thinnest samples and exhibited the highest tensile strength of the materials tested.

  20. Tooth structure and fracture strength of cavities

    DEFF Research Database (Denmark)

    Mondelli, José; Sene, Fábio; Ramos, Renata Pereira

    2007-01-01

    This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities......) or 1/2 (Groups III and VI) of the intercuspal distance. Teeth were weighed (digital balance accurate to 0.001 g) before and after preparation to record tooth substance mass lost during cavity preparation. The prepared teeth were submitted to occlusal loading to determine their fracture strength using...... mass loss (13.91%) than composite resin preparations with the same width (10.02%). 1/2-inlay cavities had 21.34% of mass loss versus 16.19% for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50...

  1. Creep Strength of Discontinuous Fibre Composites

    DEFF Research Database (Denmark)

    Pedersen, Ole Bøcker

    1974-01-01

    relation between stress and strain rate. Expressions for the interface stress, the creep velocity profile adjacent to the fibres and the creep strength of the composite are derived. Previous results for the creep strength, sc = aVfs0 ( \\frac[( Î )\\dot] [( Î )\\dot] 0 )1/nr1 + 1/n c=Vf001n1+1n in which[( Î...... )\\dot] is the composite creep rate,V f is the fibre volume fraction,sgr 0,epsi 0 andn are the constants in the matrix creep law. The creep strength coefficient agr is found to be very weakly dependent onV f and practically independent ofn whenn is greater than about 6....

  2. Mechanical properties of high-strength concrete

    Science.gov (United States)

    Mokhtarzadeh, Alireza

    This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

  3. Making High-Tensile-Strength Amalgam Components

    Science.gov (United States)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  4. Practical significance of weld strength matching

    Energy Technology Data Exchange (ETDEWEB)

    Sloterdijk, W. [N.V. Nederlandse Gasunie, Groningen (Netherlands); Schipaanboord, W.N. [N.V. Nederlandse Gasunie, Groningen (Netherlands)

    1996-10-01

    Defect tolerance in welds in pipelines constructed in modern high strength material depends on the balance in strength between weld material and pipe material. The Guidelines on the assessment of girth weld defects published by the European Pipeline Research Group (EPRG) define in Tier 2 defect limits assuming that the (actual) weld metal yield strength is equal or greater than the yield strength of the parent material. The defect limits according to Tier 2 exceed the defect limits in `workmanship standards` (l>25 mm). Nevertheless, the draft European welding standard EN 288 does not yet require a test to measure and verify the weld metal yield strength. Gasunie has performed a test program with the aim to look at the practical significance of weld strength matching in a strain controlled situation and to verify the relevance of limits given in the European welding and line pipe codes, in combination with the EPRG Guidelines. It is concluded that the results of the tests confirm the defect acceptance limits according to Tier 2 of the EPRG Guidelines. (orig.) [Deutsch] Die Zulaessigkeit von Fehlern in Rundschweissnaehten in Rohrleitungen aus modernen hochfesten Baustaehlen haengt von dem Verhaeltnis der Werkstofffestigkeit des Schweissgutes zu der des Grundwerkstoffs ab. Die von der European Pipeline Research Group (EPRG) veroeffentlichte Richtlinie zur Bewertung von Schweissnahtfehlern gibt in der zweiten Bewertungsstufe (Tier 2) Werte fuer zulaessige Schweissnahtfehlergroessen unter der Bedingung an, dass die Dehngrenze des Schweissgutes groesser oder gleich der Dehngrenze des Grundwerkstoffs ist. Die nach Tier 2 zulaessigen Fehler sind groesser als die in `Good-workmanship`-Regelwerken angegebenen Fehlerlaenge (l>25 mm). Demgegenueber fehlt im Entwurf der europaeischen Schweissnorm EN 288 bislang ein solcher Dehngrenzennachweis. Gasunie hat ein Versuchsprogramm durchgefuehrt, um die Bedeutung der Schweissgutfestigkeit bei dehnungskontrollierter Belastung sowie

  5. 走近Air

    Institute of Scientific and Technical Information of China (English)

    马华

    2007-01-01

    @@ 大家对air这个单词并不陌生,它通常用作名词,表示"空气".例如: 1.Better let in fresh air. 最好让新鲜空气进来. 2.The air smells of paint. 空气里散发着油漆味. 3.The air was heavy with perfume of the flowers. 空气里弥漫着花朵的芳香.

  6. Contact air abrasion.

    Science.gov (United States)

    Porth, R

    1999-05-01

    The advantages of contact air abrasion techniques are readily apparent. The first, of course, is the greatly increased ease of use. Working with contact also tends to speed the learning curve by giving the process a more natural dental feel. In addition, as one becomes familiar with working with a dust stream, the potential for misdirecting the air flow is decreased. The future use of air abrasion for deep decay removal will make this the treatment of choice for the next millennium.

  7. Olefin metathesis in air.

    Science.gov (United States)

    Piola, Lorenzo; Nahra, Fady; Nolan, Steven P

    2015-01-01

    Since the discovery and now widespread use of olefin metathesis, the evolution of metathesis catalysts towards air stability has become an area of significant interest. In this fascinating area of study, beginning with early systems making use of high oxidation state early transition metal centers that required strict exclusion of water and air, advances have been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance.

  8. Gaseous hydrogen embrittlement of high strength steels

    Science.gov (United States)

    Gangloff, R. P.; Wei, R. P.

    1977-01-01

    The effects of temperature, hydrogen pressure, stress intensity, and yield strength on the kinetics of gaseous hydrogen assisted crack propagation in 18Ni maraging steels were investigated experimentally. It was found that crack growth rate as a function of stress intensity was characterized by an apparent threshold for crack growth, a stage where the growth rate increased sharply, and a stage where the growth rate was unchanged over a significant range of stress intensity. Cracking proceeded on load application with little or no detectable incubation period. Gaseous hydrogen embrittlement susceptibility increased with increasing yield strength.

  9. Tensile Strength of Snow using Centrifugal Technique

    Directory of Open Access Journals (Sweden)

    Agraj Upadhyay

    2007-11-01

    Full Text Available Tensile strength of snow was determined using indigenously developed automated centrifugalmachine. Processed snow (sintered at 20 °C for 4 days samples of dia: 65 mm andheight:130 mm were tested using this machine.The experiments were conducted on sieved snowat four temperature levels of 0 °C, 3 °C,6 °C and 9 °C at density ranging from 200-460 kg/m3.Results of these experiments have been compared with the earlier  suggested models. Probabilitydistribution of snow strength on the basis of current experimental data has also been presented.

  10. MECHANICAL STRENGTH AND RELIABILITY OF SOLID CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    Yongdan Li; Dongfang Wu; Y.S. Lin

    2004-01-01

    The mechanical strength of solid catalysts is one of the key parameters for reliable and efficient performance of a fixed bed reactor. Some recent developments and their basic mechanics within this context are reviewed. The main concepts discussed are brittle fracture which leads to the mechanical failure of the catalyst pellets, measurement and statistical properties of the catalyst strength data, and mechanical reliability of the catalyst pellets and their packed bed. The scientific basis for the issues on the catalyst mechanical properties calls yet for further elucidation and advancement.

  11. Unexpected shear strength change in magnetorheological fluids

    Directory of Open Access Journals (Sweden)

    Yu Tian

    2014-09-01

    Full Text Available Smart materials of magnetorheological (MR fluids could be turned from a liquid state into a solid state, which solidification extent or shear strength often increases monotonically with the applied magnetic field. In this study, the shear stress of a dilute MR fluid decreased with increasing applied magnetic field at a constant shear rate. The dynamic shear stress was significantly higher than the stable counterpart at medium magnetic fields. They are ascribed to the slow particle structure transformation. A higher shear rate and particle volume fraction could reduce the transient time and the shear strength difference.

  12. Derivation of sink strengths in bounded media

    Energy Technology Data Exchange (ETDEWEB)

    Brailsford, A.D. (Ford Motor Co., Dearborn, MI (USA). Engineering and Research Staff)

    1981-11-01

    Several reasons for the need to extend the rate theory of point defect recovery processes to bounded media are cited. This paper is concerned with the essential first step, the derivation of the strength of sinks near a free surface. The Effective Medium method is used. Sink strengths so derived are shown to be formally the same as those found in an unbounded system. Image effects associated with the surface are proved to be small when the sink is located more than a few sink radii from the surface.

  13. Distribution of crushing strength of tablets

    DEFF Research Database (Denmark)

    Sonnergaard, Jørn

    2002-01-01

    as a material constant. However, the estimation of this parameter is laborious and subject to estimation problems. It is shown that the Weibull modulus is inherently connected to the coefficient of variation and that the information obtained from the modulus is unclear. The distribution of crushing strength...... data from nine model tablet formulations and four commercial tablets are shown to follow the normal distribution. The importance of proper cleaning of the crushing strength apparatus is demonstrated. Copyright © 2002 Elsevier Science B.V....

  14. Compressive strength of thick composite panels

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter

    2011-01-01

    The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used in the structu......The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used...

  15. Size Effects on the Strength of Metals

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2014-01-01

    The grain size effect and the specimen size effect on the strength of metals are briefly reviewed with respect to their history and current status of research. It is revealed that the fundamental strengthening mechanisms responsible for these two types of size effect are to increase the resistance...... to dislocation motion and to dislocation generation, respectively. It is shown that both strengthening mechanisms take place in some nanostructured metals, which leads to a suggestion to use these two mechanisms for optimizing the strength and ductility of nanostructured metals. This suggestion is verified...

  16. Creation of Air-Cooled Mn Series Bainitic Steels

    Institute of Scientific and Technical Information of China (English)

    FANG Hong-sheng; FENG Chun; ZHENG Yan-kang; YANG Zhi-gang; BAI Bing-zhe

    2008-01-01

    The development and mechanical performances of new type air-cooled Mn series bainitie steels including granular bainitie steels,FGBA/BG duplex steels,CFB/M duplex steels,medium carbon bainite/martensite steels,cast hainitic steels invented by the authors are summarized.The novel series of bainitie steels are alloyed with Mn,and several series bainitic duplex microstructures can be easily obtained under the condition of air cooling through unique composition design.The invented idea,the principle of alloying design,the strengthening mechanism,and the evolution of the microstructure of new type air-cooled Mn series bainitic steels are presented.Furthermore,the applications in different fields of these Mn series air-cooled bainitic steels with different strength level are also introdueed.It is suggested that the significance of the development of the air-cooled Mn series bainitic steel can be summarized as follows:reducing costs of both raw materials and production;good combination of strength and toughness;self-hardening with high bainitic hardenability by air cooling from hot working without additional quenching-tempering treatment or quenching procedure;large savings in energy resources;and reduced environmental pollution.

  17. Burst strength of tubing and casing based on twin shear unified strength theory.

    Science.gov (United States)

    Lin, Yuanhua; Deng, Kuanhai; Sun, Yongxing; Zeng, Dezhi; Liu, Wanying; Kong, Xiangwei; Singh, Ambrish

    2014-01-01

    The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

  18. Progress of catalytic wet air oxidation technology

    Directory of Open Access Journals (Sweden)

    Guolin Jing

    2016-11-01

    Full Text Available Catalytic wet air oxidation (CWAO is one of the most economical and environmental-friendly advanced oxidation process for high strength, toxic, hazardous and non-biodegradable contaminants under milder conditions, which is developed on the basic of wet air oxidation. Various heterogeneous catalysts including noble metals and metal oxides have been extensively studied to enhance the efficiency of CWAO. The advances in the research on wastewater treatment by CWAO process are summarized in aspects of reaction mechanism investigation, reaction kinetics study and catalyst development. It is pointed out that the preparation of active and stable catalysts, the investigation on reaction mechanisms and the study on reaction kinetics models are very important for the promotion of CWAO application.

  19. Strength of precast concrete shear joints reinforced with high-strength wire ropes

    DEFF Research Database (Denmark)

    Joergensen, Henrik B.; Hoang, Linh Cao; Hagsten, Lars German

    2017-01-01

    This paper concerns the in-plane shear strength of connections between precast concrete wall elements reinforced with looped high-strength wire ropes. The looped wire ropes are pre-installed in so-called ‘wire boxes’ which function as shear keys. Although only a small amount of research...... on the shear strength of such connections can be found in the literature, this type of connection is increasingly being used because wire ropes are much more construction-friendly than traditional U-bars. A rigid plastic upper bound model for the shear strength of wall connections reinforced with looped wire...... ropes that are pre-installed in wire boxes is presented along with test results on the shear strength of connections with double-wire boxes. It is shown that the plastic solution agrees well with both the obtained test results and results from previously conducted tests....

  20. Nanoparticle transport in water-unsaturated porous media: effects of solution ionic strength and flow rate

    Science.gov (United States)

    Prédélus, Dieuseul; Lassabatere, Laurent; Louis, Cédric; Gehan, Hélène; Brichart, Thomas; Winiarski, Thierry; Angulo-Jaramillo, Rafael

    2017-03-01

    This paper presents the influence of ionic strength and flow on nanoparticle (NP) retention rate in an unsaturated calcareous medium, originating from a heterogeneous glaciofluvial deposit of the region of Lyon (France). Laboratory columns 10 cm in diameter and 30 cm in length were used. Silica nanoparticles (Au-SiO2-FluoNPs), with hydrodynamic diameter ranging from 50 to 60 nm and labeled with fluorescein derivatives, were used to simulate particle transport, and bromide was used to characterize flow. Three flow rates and five different ionic strengths were tested. The transfer model based on fractionation of water into mobile and immobile fractions was coupled with the attachment/detachment model to fit NPs breakthrough curves. The results show that increasing flow velocity induces a decrease in nanoparticle retention, probably as the result of several physical but also geochemical factors. The results show that NPs retention increases with ionic strength. However, an inversion of retention occurs for ionic strength >5.10-2 M, which has been scarcely observed in previous studies. The measure of zeta potential and DLVO calculations show that NPs may sorb on both solid-water and air-water interfaces. NPs size distribution shows the potential for nanoparticle agglomeration mostly at low pH, leading to entrapment in the soil pores. These mechanisms are highly sensitive to both hydrodynamic and geochemical conditions, which explains their high sensitivity to flow rates and ionic strength.

  1. Effect of preoxidation on the bond strength of titanium and porcelain.

    Science.gov (United States)

    Mahale, K M; Nagda, S J

    2014-06-01

    The purpose of this study was to investigate the effect of preoxidation on porcelain titanium- bond strength and the effect of paste bonder (adhesive) on the titanium porcelain bond strength. 11 specimens of commercially pure titanium (26 x 7 x 3 mm) were prepared by different heat treatments in programmable dental furnace. Identification of the oxides formed on the metal surface was conducted with an X-Ray diffractometer with CuKalpha radiation. Vickers hardness numbers were determine. Additional 50 specimens of commercially pure titanium were used to bond with low fusing porcelain. The bond strength was measured in a universal testing machine. X-ray diffraction analysis of the surface of pure titanium revealed that the relative peak intensity of alpha -Ti decreased and that of TiO2 increased with increasing firing temperature. The Vickers hardness number decreased initially as the temperature increased but it increased remarkably above 900 degrees C & was harder in air than vacuum. The tensile shear bond strength was highest in the green stage i.e. without preoxidation of metal, and decreased above 900 degrees C, and was the lowest in the group without paste bonder application. The difference in bond strengths was statistically highly significant for all groups. Preoxidation under vacuum before porcelain firing can effectively improve bonding. The adhesive provided with the low fusing porcelain helps in the bond between titanium & porcelain.

  2. Does Weak Turbulence Impact PMSEs' Strengths Closer To The Northern Pole?

    Science.gov (United States)

    Swarnalingam, N.; Hocking, W. K.; Janches, D.; Nicolls, M. J.

    2015-12-01

    Existing 51.0 MHz VHF radar at Eureka (80N, 86W) in northern Canada is located closer to both the northern magnetic and geomagnetic poles. A recent calibrated study of Polar Mesosphere Summer Echoes (PMSE) using this radar supports the previous results by other radars that the absolute signal strength of PMSE in this region is relatively weak compared with the radar observations located at high latitudes. Although very cold temperature and existence of charged ice particles are the most important ingredient required for PMSE to appear, several other factors could potentially influence the absolute signal strengths of these echoes. One of them is neutral air turbulence. Previous studies indicate that upper mesospheric turbulence's strength decreases with latitudes, especially in the very high latitudes [Becker, 2004; Lubken et. al., 2009]. In this study, we investigate long-term mesospheric turbulence strengths at Eureka and study how they could be associated with the weak PMSE signal strengths compared with other high latitude conditions, where PMSE are strong.

  3. Development of Yield and Tensile Strength Design Curves for Alloy 617

    Energy Technology Data Exchange (ETDEWEB)

    Nancy Lybeck; T. -L. Sham

    2013-10-01

    The U.S. Department of Energy Very High Temperature Reactor Program is acquiring data in preparation for developing an Alloy 617 Code Case for inclusion in the nuclear section of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. A draft code case was previously developed, but effort was suspended before acceptance by ASME. As part of the draft code case effort, a database was compiled of yield and tensile strength data from tests performed in air. Yield strength and tensile strength at temperature are used to set time independent allowable stress for construction materials in B&PV Code, Section III, Subsection NH. The yield and tensile strength data used for the draft code case has been augmented with additional data generated by Idaho National Laboratory and Oak Ridge National Laboratory in the U.S. and CEA in France. The standard ASME Section II procedure for generating yield and tensile strength at temperature is presented, along with alternate methods that accommodate the change in temperature trends seen at high temperatures, resulting in a more consistent design margin over the temperature range of interest.

  4. Got LEGO Bricks? Children with Spatial Strengths

    Science.gov (United States)

    Mann, Rebecca

    2013-01-01

    Individuals with spatial strengths have preferences for visual ideation, holistic reasoning, and innovation. With the emphasis on verbal skills, American schools rarely provide opportunities for children to excel in these areas. Standardized assessments used to judge achievement do not value reflective thinking and innovation; therefore, students…

  5. Investigation of strength properties of freshwater ice

    Directory of Open Access Journals (Sweden)

    Bragov A.

    2015-01-01

    Full Text Available A study of the strength and deformation properties of freshwater ice under compression, tension and shear in a wide range of strain rates (10−4 − 3 ⋅ 103 s−1 and temperatures of − 5∘ C, − 20∘ C, − 40∘ C and − 60∘ C was performed. Static stress-strain curves of ice under compression were obtained on which the identified strength properties of ice as well as compressive modulus. To determine the mechanical properties of ice at high-speed loading the Kolsky method was used with various embodiments of split Hopkinson bar. The deformation curves were obtained at various loading conditions. Thereon breaking points were defined as well as their dependence on the strain rate and temperature. Also static and dynamic strength properties of ice at splitting and circular shear were defined. Increase in the dynamic strength properties upon the static ones for all loading conditions was marked.

  6. Shear adhesion strength of aligned electrospun nanofibers.

    Science.gov (United States)

    Najem, Johnny F; Wong, Shing-Chung; Ji, Guang

    2014-09-01

    Inspiration from nature such as insects' foot hairs motivates scientists to fabricate nanoscale cylindrical solids that allow tens of millions of contact points per unit area with material substrates. In this paper, we present a simple yet robust method for fabricating directionally sensitive shear adhesive laminates. By using aligned electrospun nylon-6, we create dry adhesives, as a succession of our previous work on measuring adhesion energies between two single free-standing electrospun polymer fibers in cross-cylinder geometry, randomly oriented membranes and substrate, and peel forces between aligned fibers and substrate. The synthetic aligned cylindrical solids in this study are electrically insulating and show a maximal Mode II shear adhesion strength of 27 N/cm(2) on a glass slide. This measured value, for the purpose of comparison, is 270% of that reported from gecko feet. The Mode II shear adhesion strength, based on a commonly known "dead-weight" test, is 97-fold greater than the Mode I (normal) adhesion strength of the same. The data indicate a strong shear binding on and easy normal lifting off. Anisotropic adhesion (Mode II/Mode I) is pronounced. The size and surface boundary effects, crystallinity, and bending stiffness of fibers are used to understand these electrospun nanofibers, which vastly differ from otherwise known adhesive technologies. The anisotropic strength distribution is attributed to a decreasing fiber diameter and an optimized laminate thickness, which, in turn, influences the bending stiffness and solid-state "wettability" of points of contact between nanofibers and surface asperities.

  7. Measuring TGV source strength with Syntacan

    NARCIS (Netherlands)

    Toorn, J.D. van der; Hendriks, H.; Dool, T.C. van den

    1996-01-01

    A 10 m high, vertical, synthetic acoustic antenna (Syntacan) has been used to measure the acoustic source strength and the vertical source distribution of a French TGV, as a function of the speed of the train, the frequency of the sound and the coach type (passenger coach, power car). The results ar

  8. Computer Simulation in Problems of Thermal Strength

    Directory of Open Access Journals (Sweden)

    Olga I. Chelyapina

    2012-05-01

    Full Text Available This article discusses informative technology of using graphical programming environment LabVIEW 2009 when calculating and predicting the thermal strength of materials with an inhomogeneous structure. Algorithm for processing the experimental data was developed as part of the problem.

  9. The structural strength of glass: hidden damage

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2011-01-01

    We discuss “hidden damage” of glass by the rolling process, which results in heterogeneous distribution of microcracks on the edge surface of glass element, which are the fracture source deteriorating glass element strength. It is shown that removal of this damage on the edges of glass elements incr

  10. An improved device to measure cottonseed strength

    Science.gov (United States)

    During processing, seeds of cotton cultivars with fragile seeds often break and produce seed coat fragments that can cause processing problems at textile mills. A cottonseed shear tester, previously developed to measure cottonseed strength, was modified with enhancements to the drive system to provi...

  11. A novel limiting strain energy strength theory

    Institute of Scientific and Technical Information of China (English)

    LIU Guang-lian

    2009-01-01

    With applied dislocation theory,the effects of shear and normal stresses on the slide and climb motions at the same section of a crystal were analyzed.And,based on the synergetic effect of both normal and shear strain specific energies,the concept of the total equivalent strain specific energy (TESSE) at an oblique section and a new strength theory named as limiting strain energy strength theory (LSEST) were proposed.As for isotropic materials,the plastic yielding or brittle fracture of under uniaxial stress state would occur when the maximum TESSE reached the strain specific energy,also the expressions on the equivalent stresses and a function of failure of the LSEST under different principal stress states were obtained.Relationship formulas among the tensile,compressive and shear yield strengths for plastic metals were derived.These theoretical predictions,according to the LSEST,were consistent very well with experiment results of tensile,compressive and torsion tests of three plastic metals and other experiment results from open literatures.This novel LSEST might also help for strength calculation of other materials.

  12. Strength Training. A Key to Athletic Training.

    Science.gov (United States)

    Whiteside, Patricia W.

    Characteristics of an effective strength training program are analyzed and descriptions are offered of different kinds of weight training activities. Comparisons are made between concentric, isometric, eccentric, and isokinetic training methods. The fundamentals and techniques of an exemplary training program are outlined and the organization and…

  13. Promoting Client Strength Through Positive Addiction

    Science.gov (United States)

    Glasser, William

    1977-01-01

    Under certain conditions self-improvement activities like running or meditating can become addictive. This article contends that such addictions confer strength to the individual and promote effective living; therefore, they must be considered "positive". The article traces the development of the concept of positive addiction. (Author)

  14. The Strengths and Weaknesses of Universal Grammar

    Institute of Scientific and Technical Information of China (English)

    华芳

    2013-01-01

      Chomsky’s universal grammar (UG) has always had a following among certain linguists. This article discusses the strengths and weaknesses of UG in the L2 setting according to its proponents and opponents. The author also evaluates it using Ka⁃plan’s five-point tool and Long’s eight-point measuring stick.

  15. Springback analysis of ultra high strength steel

    Science.gov (United States)

    Tenma, Kenji; Kina, Futoshi; Suzuki, Wataru

    2013-12-01

    It is an inevitable trend in the automotive industry to apply more and more high strength steels and even ultra-high strength steels. Even though these materials are more difficult to process the development time of forming tools must be reduced. In order to keep the development time under control, simulation tools are used to verify the forming process in advance. At Aoi Machine Industry a project has been executed to accurately simulate springback of ultra-high strength steels in order to reduce the tool tryout time. In the first phase of the project the simulation settings were optimized based on B-Pillar model A made of Dual Phase 980. In the second phase, it was verified with B-Pillar model B whether these simulation settings were usable as general setting. Results showed that with the right settings it is very well possible to accurately simulate springback of ultra-high strength steels. In the third phase the project the stamping of a B-Pillar of Dual Phase 1180 was studied.

  16. Ultimate Strength of Ship Hulls under Torsion

    DEFF Research Database (Denmark)

    Paik, Jeom Kee; Thayamballi, Anil K.; Pedersen, Preben Terndrup

    2001-01-01

    For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength characte......For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength...... characteristics of ships with large hatch openings. The primary aim of the present study is to investigate the ultimate strength characteristics of ship hulls with large hatch openings under torsion. Axial (warping) as well as shear stresses are normally developed for thin-walled beams with open cross sections...... analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce the ship hull ultimate bending moment....

  17. Concrete Strength for Fire Safety Design

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    2005-01-01

    Idealized data are derived for the compressive strength of a number of concretes for fire safety design. The data are derived from the authors own research including test series not published before and from more than 400 other test series comprising approximately 3000 specimens known from...

  18. Strength variability of single flax fibres

    DEFF Research Database (Denmark)

    Aslan, Mustafa; Chinga-Carrasco, G.; Sørensen, Bent F.

    2011-01-01

    (linear and nonlinear) of the fibres are found to be correlated with the amount of defects. The linear stress–strain curves tend to show a higher tensile strength, a higher Young’s modulus, and a lower strain to failure than the nonlinear curves. Finally, the fibres are found to fracture by a complex...

  19. COMPETITION BUILDS STRENGTH IN FINANCIAL MARKETS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Transitioning from a“planned”economy to a“market”economy may be a long and arduous task for China,but opening its financial markets to foreign competition will help build stability and strength for the Chinese economy, says U.S.Ambassador Alan Holmer.Hol

  20. Abnormality in fracture strength of polycrystalline silicene

    Science.gov (United States)

    Liu, Ning; Hong, Jiawang; Pidaparti, Ramana; Wang, Xianqiao

    2016-09-01

    Silicene, a silicon-based homologue of graphene, arouses great interest in nano-electronic devices due to its outstanding electronic properties. However, its promising electronic applications are greatly hindered by lack of understanding in the mechanical strength of silicene. Therefore, in order to design mechanically reliable devices with silicene, it is necessary to thoroughly explore the mechanical properties of silicene. Due to current fabrication methods, graphene is commonly produced in a polycrystalline form; the same may hold for silicene. Here we perform molecular dynamics simulations to investigate the mechanical properties of polycrystalline silicene. First, an annealing process is employed to construct a more realistic modeling structure of polycrystalline silicene. Results indicate that a more stable structure is formed due to the breaking and reformation of bonds between atoms on the grain boundaries. Moreover, as the grain size decreases, the efficiency of the annealing process, which is quantified by the energy change, increases. Subsequently, biaxial tensile tests are performed on the annealed samples in order to explore the relation between grain size and mechanical properties, namely in-plane stiffness, fracture strength and fracture strain etc. Results indicate that as the grain size decreases, the fracture strain increases while the fracture strength shows an inverse trend. The decreasing fracture strength may be partly attributed to the weakening effect from the increasing area density of defects which acts as the reservoir of stress-concentrated sites on the grain boundary. The observed crack localization and propagation and fracture strength are well-explained by a defect-pileup model.

  1. High-strength mineralized collagen artificial bone

    Science.gov (United States)

    Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

    2014-03-01

    Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

  2. AIR RADIOACTIVITY MONITOR

    Science.gov (United States)

    Bradshaw, R.L.; Thomas, J.W.

    1961-04-11

    The monitor is designed to minimize undesirable background buildup. It consists of an elongated column containing peripheral electrodes in a central portion of the column, and conduits directing an axial flow of radioactively contaminated air through the center of the column and pure air through the annular portion of the column about the electrodes. (AEC)

  3. Air-Conditioning Mechanic.

    Science.gov (United States)

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by air conditioning mechanics. Addressed in the four chapters, or lessons, of the manual are the following topics: principles of air conditioning, refrigeration components as…

  4. The Air We Breathe

    Science.gov (United States)

    Davila, Dina

    2010-01-01

    Topics discussed include NASA mission to pioneer the future in space exploration, scientific discovery and aeronautics research; the role of Earth's atmosphere, atmospheric gases, layers of the Earth's atmosphere, ozone layer, air pollution, effects of air pollution on people, the Greenhouse Effect, and breathing on the International Space Station.

  5. Air/liquid collectors

    DEFF Research Database (Denmark)

    Jensen, Søren Østergaard; Olesen, Ole; Kristiansen, Finn Harken

    1997-01-01

    This report determine efficiency equations for combined air/liquid solar collectors by measurements on to different air/liquid collectors. Equations which contain all relevant informations on the solar collectors. A simulation program (Kviksol) has been modified in order to be able to handle...

  6. Bad Air For Children

    Science.gov (United States)

    Kane, Dorothy Noyes

    1976-01-01

    Children are especially sensitive to air pollution and consequences to them maybe of longer duration than to adults. The effects of low-level pollution on children are the concern of this article. The need for research on the threat of air pollution to childrens' health is emphasized. (BT)

  7. Air pollution and society

    OpenAIRE

    Brimblecombe P.

    2010-01-01

    Air pollution is as much a product of our society as it is one of chemistry and meteorology. Social variables such as gender, age, health status and poverty are often linked with our exposure to air pollutants. Pollution can also affect our behaviour, while regulations to improve the environment can often challenge of freedom.

  8. Over the air test

    DEFF Research Database (Denmark)

    2015-01-01

    [1] This invention relates to over-the-air testing of a device in an anechoic chamber. In particular, the invention is suitable for simulating both uplink and downlink over-the-air communication with a device under test even when the anechoic chamber has different numbers of uplink and downlink...

  9. Air Pollution, Teachers' Edition.

    Science.gov (United States)

    Lavaroni, Charles W.; O'Donnell, Patrick A.

    One of three in a series about pollution, this teacher's guide for a unit on air pollution is designed for use in junior high school grades. It offers suggestions for extending the information and activities contained in the textual material for students. Chapter 1 discusses the problem of air pollution and involves students in processes of…

  10. Air Pollution and Industry.

    Science.gov (United States)

    Ross, R. D., Ed.

    This book is an authoritative reference and practical guide designed to help the plant engineer identify and solve industrial air pollution problems in order to be able to meet current air pollution regulations. Prepared under the editorial supervision of an experienced chemical engineer, with each chapter contributed by an expert in his field,…

  11. Bearings Only Air-to-Air Ranging

    Science.gov (United States)

    1988-07-25

    sensor, observer and target parameters still remain. In order to reduce the number of cases to a manageable one, while preserving the geometric...perforance of variotu. ulro-air passive ranging tecnique has been examined as a fimn- tiam of uarget location andi motiom, observer motion. and length

  12. Restoran Buenos Aires = Restaurant Buenos Aires

    Index Scriptorium Estoniae

    2008-01-01

    Restorani Buenos Aires (Narva mnt. 5, Tallinn) sisekujundusest. Sisearhitektid: Janno Roos ja Andres Labi (Ruumilabor OÜ). Laudu eraldavad 400 vardasse aetud puukuuli. Sisearhitektidest, nende tähtsamad tööd. I-III korruse plaan, 12 värv. vaadet, fotod sisearhitektidest

  13. EFFECTS OF SELF-SELECTED MUSIC ON MAXIMAL BENCH PRESS STRENGTH AND STRENGTH ENDURANCE.

    Science.gov (United States)

    Bartolomei, Sandro; Di Michele, Rocco; Merni, Franco

    2015-06-01

    Listening to music during strength workouts has become a very common practice. The goal of this study was to assess the effect of listening to self-selected music on strength performances. Thirty-one resistance-trained men (M age = 24.7 yr., SD = 5.9; M height = 178.7 cm, SD = 4.7; M body mass = 83.54 kg, SD = 12.0) were randomly assigned to either a Music group (n = 19) or to a Control group (n = 12). Both groups took part in two separate sessions; each session consisted in a maximal strength test (1-RM) and a strength-endurance test (repetitions to failure at 60% 1-RM) using the bench press exercise. The music group listened to music in the second assessment session, while the control group performed both tests without music. Listening to music induced a significant increase of strength endurance performance and no effects on maximal strength. These findings have implications for the use of music during strength workouts.

  14. Handgrip Strength: Indications of Paternal Inheritance in Three European Regions

    DEFF Research Database (Denmark)

    Cournil, Amandine; Jeune, Bernard; Skytthe, Axel

    2010-01-01

    BACKGROUND: Handgrip strength is an indicator of overall muscle strength. Poor handgrip strength is a risk factor for disability and mortality. We aimed to investigate the pattern of inheritance of handgrip strength in a sample of parent-offspring pairs from three different European regions in De...

  15. 49 CFR 230.26 - Tensile strength of shell plates.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tensile strength of shell plates. 230.26 Section... Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell plates is not known, it shall be taken at 50,000 psi for steel and...

  16. Hip adduction and abduction strength profiles in elite soccer players

    DEFF Research Database (Denmark)

    Thorborg, Kristian; Serner, Andreas; Petersen, Jesper;

    2011-01-01

    An ipsilateral hip adduction/abduction strength ratio of more than 90%, and hip adduction strength equal to that of the contralateral side have been suggested to clinically represent adequate strength recovery of hip adduction strength in athletes after groin injury. However, to what extent side...

  17. AIRE-Linux

    Science.gov (United States)

    Zhou, Jianfeng; Xu, Benda; Peng, Chuan; Yang, Yang; Huo, Zhuoxi

    2015-08-01

    AIRE-Linux is a dedicated Linux system for astronomers. Modern astronomy faces two big challenges: massive observed raw data which covers the whole electromagnetic spectrum, and overmuch professional data processing skill which exceeds personal or even a small team's abilities. AIRE-Linux, which is a specially designed Linux and will be distributed to users by Virtual Machine (VM) images in Open Virtualization Format (OVF), is to help astronomers confront the challenges. Most astronomical software packages, such as IRAF, MIDAS, CASA, Heasoft etc., will be integrated into AIRE-Linux. It is easy for astronomers to configure and customize the system and use what they just need. When incorporated into cloud computing platforms, AIRE-Linux will be able to handle data intensive and computing consuming tasks for astronomers. Currently, a Beta version of AIRE-Linux is ready for download and testing.

  18. The influence of strength, flexibility, and simultaneous training on flexibility and strength gains.

    Science.gov (United States)

    Simão, Roberto; Lemos, Adriana; Salles, Belmiro; Leite, Thalita; Oliveira, Élida; Rhea, Matthew; Reis, Victor Machado

    2011-05-01

    The purpose of this study was to examine the strength and flexibility gains after isolated or simultaneous strength and flexibility training after 16 weeks. Eighty sedentary women were randomly assigned to 1 of 4 groups: strength training (ST; n = 20), flexibility training (FLEX) (n = 20), combination of both (ST + FLEX; n = 20) and control group (CG; n = 20). All the groups performed pre and posttraining sit and reach test to verify the flexibility level and 10RM test for leg press and bench press exercises. The training protocol for all groups, except for the CG, included 3 weekly sessions, in alternated days, totaling 48 sessions. Strength training was composed of 8 exercises for upper and lower body, executed in 3 sets of periodized training. The flexibility training was composed of static stretching exercises that involved upper and lower body. Results showed that ST (30 ± 2.0 to 36 ± 3.0 cm), ST + FLEX (31 ± 1.0 to 42 ± 4.0 cm), and FLEX (32 ± 3.0 to 43 ± 2.0 cm) significantly increased in flexibility in relation to baseline and to CG (30 ± 2.0 to 30 ± 2.0 cm); however, no significant differences were observed between the treatment conditions. Strength tests demonstrated that ST and ST + FLEX significantly increased 10RM when compared to baseline, FLEX, and the CG. In conclusion, short-term strength training increases flexibility and strength in sedentary adult women. Strength training may contribute to the development and maintenance of flexibility even without the inclusion of additional stretching, but strength and flexibility can be prescribed together to get optimal improvements in flexibility.

  19. At-home resistance tubing strength training increases shoulder strength in the trained and untrained limb.

    Science.gov (United States)

    Magnus, C R A; Boychuk, K; Kim, S Y; Farthing, J P

    2014-06-01

    The purpose was to determine if an at-home resistance tubing strength training program on one shoulder (that is commonly used in rehabilitation settings) would produce increases in strength in the trained and untrained shoulders via cross-education. Twenty-three participants were randomized to TRAIN (strength-trained one shoulder; n = 13) or CONTROL (no intervention; n = 10). Strength training was completed at home using resistance tubing and consisted of maximal shoulder external rotation, internal rotation, scaption, retraction, and flexion 3 days/week for 4 weeks. Strength was measured via handheld dynamometry and muscle size measured via ultrasound. For external rotation strength, the trained (10.9 ± 10.9%) and untrained (12.7 ± 9.6%) arm of TRAIN was significantly different than CONTROL (1.6 ± 13.2%; -2.7 ± 12.3%; pooled across arm; P strength, the trained (14.8 ± 11.3%) and untrained (14.6 ± 10.1%) arm of TRAIN was significantly different than CONTROL (6.4 ± 11.2%; 5.1 ± 8.8%; pooled across arm; P strength (P = 0.056). TRAIN significantly increased muscle size in the training arm of the supraspinatus (1.90 ± 0.32 to 1.99 ± 0.31 cm), and the anterior deltoid (1.08 ± 0.37 to 1.21 ± 0.39 cm; P training program on one limb can produce increases in strength in both limbs, and has implications for rehabilitation after unilateral shoulder injuries.

  20. Airing 'clean air' in Clean India Mission.

    Science.gov (United States)

    Banerjee, T; Kumar, M; Mall, R K; Singh, R S

    2016-12-30

    The submission explores the possibility of a policy revision for considering clean air quality in recently launched nationwide campaign, Clean India Mission (CIM). Despite of several efforts for improving availability of clean household energy and sanitation facilities, situation remain still depressing as almost half of global population lacks access to clean energy and proper sanitation. Globally, at least 2.5 billion people do not have access to basic sanitation facilities. There are also evidences of 7 million premature deaths by air pollution in year 2012. The situation is even more disastrous for India especially in rural areas. Although, India has reasonably progressed in developing sanitary facilities and disseminating clean fuel to its urban households, the situation in rural areas is still miserable and needs to be reviewed. Several policy interventions and campaigns were made to improve the scenario but outcomes were remarkably poor. Indian census revealed a mere 31% sanitation coverage (in 2011) compared to 22% in 2001 while 60% of population (700 million) still use solid biofuels and traditional cook stoves for household cooking. Further, last decade (2001-2011) witnessed the progress decelerating down with rural households without sanitation facilities increased by 8.3 million while minimum progress has been made in conversion of conventional to modern fuels. To revamp the sanitation coverage, an overambitious nationwide campaign CIM was initiated in 2014 and present submission explores the possibility of including 'clean air' considerations within it. The article draws evidence from literatures on scenarios of rural sanitation, energy practises, pollution induced mortality and climatic impacts of air pollution. This subsequently hypothesised with possible modification in available technologies, dissemination modes, financing and implementation for integration of CIM with 'clean air' so that access to both sanitation and clean household energy may be

  1. Damage and Fracture Strength Behavior of Jointed Rockmass

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The strength of rockmass from two aspects is analyzed.Firstly,the strength of the rockmass is mainly controlled by the critical stress value of rock,and the contribution of joints is to increase the effective stresses of rock and to decrease the damage strength of rockmass according to the macro-damage mechanics of rockmass.Secondly,the strength of rockmass is mainly controlled by the fracture strength of joints.Based on the comprehensive analysis and comparison for the damage strength of rockmass and the fracture strength of joints,a composite damage theory of rockmass may be established.

  2. Location Problem of Air Materials Supply Center for Air Force

    Institute of Scientific and Technical Information of China (English)

    王涛; 何亚群; 陶学禹

    2002-01-01

    Based on the analysis of three influencing factors on the air material supply center location, the location model of air material supply center was established. By solving the model, the rational supply center of air materials was also determined.

  3. Air Baltic: Estonian Air on nurka surutud / Teele Tammeorg

    Index Scriptorium Estoniae

    Tammeorg, Teele

    2010-01-01

    Air Balticu asepresidendi Janis Vanagsi hinnangul on Estonian Air aastaid jätnud tähelepanuta oma peamised turismiturud ning on praegu halvas seisus. Air Baltic on endiselt huvitatud Estonian Airi ostust. Majandus- ja kommunikatsiooniminister Juhan Partsi seisukoht

  4. Achievable field strength in reverberation chambers

    Directory of Open Access Journals (Sweden)

    N. Eulig

    2003-01-01

    Full Text Available Feldvariable Kammern (FVK, engl.: modestirred- chamber werden unter anderem für EMV-Störfestigkeitsprüfungen verwendet. Ein häufig genanntes Argument, das die Einführung dieser Kammern als normgerechte Prüfumgebung vorantreiben soll, ist eine hohe Feldstärke, die im Vergleich zu anderen Testumgebungen mit relativ moderaten HF-Leistungen erreicht werden kann. Besonders für sicherheitskritische Geräte, wie Komponenten aus der Avionik- oder KFZ-Industrie, sind heutzutage Testfeldstärken von mehreren 100 V/m notwendig. Derart hohe Feldstärken können in Umgebungen, die ein ebenes Wellenfeld erzeugen oder nachbilden, nur mit großen HFLeistungen generiert werden. Durch die Resonanzeigenschaften einer FVK können demgegenüber mit sehr viel weniger Leistung und damit Verstärkeraufwand vergleichbare Werte der Feldstärke erzeugt werden. Allerdings sinkt mit zunehmendem Volumen die erreichbare Feldstärke bei gleicher Speiseleistung. Idealerweise sollen Feldvariable Kammern bei möglichst niedrigen Frequenzen für EMVTests nutzbar sein, was jedoch ein großes Kammervolumen erfordert. Das Problem, bei niedrigen Frequenzen hohe Feldstärken erzeugen zu können, relativiert deshalb den Vorteil von FVKn gegenüber bekannten Testumgebungen bei niedrigen Testfrequenzen. Der Posterbeitrag erläutert, welche Feldstärken in verschieden großen Feldvariablen Kammern beim Einspeisen einer bestimmten hochfrequenten Leistung erreicht werden können. Anhand dieser Ergebnisse wird aufgezeigt, oberhalb welcher Grenzfrequenz eine Anwendung von FVKn nur sinnvoll erscheint. Mode-stirred chambers (MSCs can be used for radiated immunity tests in EMC testing. Advantageous compared to conventional test methods is the high field strength which can here be generated with less RF-Power. This point is often the main argument for pushing the standardization of MSCs as an other EMC testing environment. Especially for safety-critical electronic equipment like avionic or

  5. Hip adduction and abduction strength profiles in elite soccer players

    DEFF Research Database (Denmark)

    Serner, Andreas; Petersen, Jesper; Madsen, Thomas Moller

    2011-01-01

    An ipsilateral hip adduction/abduction strength ratio of more than 90%, and hip adduction strength equal to that of the contralateral side have been suggested to clinically represent adequate strength recovery of hip adduction strength in athletes after groin injury. However, to what extent side-......-to-side symmetry in isometric hip adduction and abduction strength can be assumed in soccer players remains uncertain....

  6. Air Cleaning Technologies

    Science.gov (United States)

    2005-01-01

    Executive Summary Objective This health technology policy assessment will answer the following questions: When should in-room air cleaners be used? How effective are in-room air cleaners? Are in-room air cleaners that use combined HEPA and UVGI air cleaning technology more effective than those that use HEPA filtration alone? What is the Plasmacluster ion air purifier in the pandemic influenza preparation plan? The experience of severe acute respiratory syndrome (SARS) locally, nationally, and internationally underscored the importance of administrative, environmental, and personal protective infection control measures in health care facilities. In the aftermath of the SARS crisis, there was a need for a clearer understanding of Ontario’s capacity to manage suspected or confirmed cases of airborne infectious diseases. In so doing, the Walker Commission thought that more attention should be paid to the potential use of new technologies such as in-room air cleaning units. It recommended that the Medical Advisory Secretariat of the Ontario Ministry of Health and Long-Term Care evaluate the appropriate use and effectiveness of such new technologies. Accordingly, the Ontario Health Technology Advisory Committee asked the Medical Advisory Secretariat to review the literature on the effectiveness and utility of in-room air cleaners that use high-efficiency particle air (HEPA) filters and ultraviolet germicidal irradiation (UVGI) air cleaning technology. Additionally, the Ontario Health Technology Advisory Committee prioritized a request from the ministry’s Emergency Management Unit to investigate the possible role of the Plasmacluster ion air purifier manufactured by Sharp Electronics Corporation, in the pandemic influenza preparation plan. Clinical Need Airborne transmission of infectious diseases depends in part on the concentration of breathable infectious pathogens (germs) in room air. Infection control is achieved by a combination of administrative, engineering

  7. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  8. Air Quality Management Process Cycle

    Science.gov (United States)

    Air quality management are activities a regulatory authority undertakes to protect human health and the environment from the harmful effects of air pollution. The process of managing air quality can be illustrated as a cycle of inter-related elements.

  9. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation??s (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  10. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation's (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  11. Does grip strength on the unaffected side of patients with hemiparetic stroke reflect the strength of other ipsilateral muscles?

    Science.gov (United States)

    Takahashi, Jumpei; Nishiyama, Toru; Matsushima, Yoshimasa

    2017-01-01

    [Purpose] Grip strength is used as an indicator of overall body muscular strength. However, most studies on grip strength have been performed in healthy people, and no study has evaluated it in the unaffected side of patients with hemiparetic stroke. The purpose of this study was to determine if grip strength on the unaffected side of patients with hemiparetic stroke correlates with the strength of other ipsilateral musculature. [Subjects and Methods] The maximal strengths of the muscles on the unaffected side of 31 patients with hemiparetic stroke were measured, and correlation coefficients were calculated. [Results] The results revealed significant positive correlations between grip strength on the unaffected side and the strength of the other ipsilateral muscle groups, with relatively high correlations being observed for the upper extremity muscle groups. [Conclusion] This suggests that grip strength on the unaffected side of patients with hemiparetic stroke can be used as a simple way to estimate overall strength on that side.

  12. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  13. The Bendability of Ultra High strength Steels

    Science.gov (United States)

    Hazra, S. K.; Efthymiadis, P.; Alamoudi, A.; Kumar, R. L. V.; Shollock, B.; Dashwood, R.

    2016-08-01

    Automotive manufacturers have been reducing the weight of their vehicles to meet increasingly stringent environmental legislation that reflects public demand. A strategy is to use higher strength materials for parts with reduced cross-sections. However, such materials are less formable than traditional grades. The frequent result is increased processing and piece costs. 3D roll forming is a novel and flexible process: it is estimated that a quarter of the structure of a vehicle can be made with a single set of tooling. Unlike stamping, this process requires material with low work hardening rates. In this paper, we present results of ultra high strength steels that have low elongation in a tension but display high formability in bending through the suppression of the necking response.

  14. Theory of Arched Structures Strength, Stability, Vibration

    CERN Document Server

    Karnovsky, Igor A

    2012-01-01

    Theory of Arched Structures: Strength, Stability, Vibration presents detailed procedures for analytical analysis of the strength, stability, and vibration of arched structures of different types, using exact analytical methods of classical structural analysis. The material discussed is divided into four parts. Part I covers stress and strain with a particular emphasis on analysis; Part II discusses stability and gives an in-depth analysis of elastic stability of arches and the role that matrix methods play in the stability of the arches; Part III presents a comprehensive tutorial on dynamics and free vibration of arches, and forced vibration of arches; and Part IV offers a section on special topics which contains a unique discussion of plastic analysis of arches and the optimal design of arches.

  15. Photophoretic Strength on Chondrules 1: Modeling

    CERN Document Server

    Loesche, Christoph; Teiser, Jens; Friedrich, Jon M; Bischoff, Addi

    2013-01-01

    Photophoresis is a physical process that transports particles in optical thin parts of protoplanetary disks, especially at the inner edge and at the optically surface. To model the transport and resulting effects in detail, it is necessary to quantify the strength of photophoresis for different particle classes as a fundamental input. Here, we explore photophoresis for a set of chondrules. The composition and surface morphology of these chondrules was measured by X-ray tomography. Based on the three-dimensional models, heat transfer through illuminated chondrules was calculated. The resulting surface temperature map was then used to calculate the photophoretic strength. We found that irregularities in particle shape and variations in composition induce variations in the photophoretic force. These depend on the orientation of a particle with respect to the light source. The variations of the absolute value of the photophoretic force on average over all chondrules is $4.17\\%$. The deviation between the directio...

  16. Ultimate strength performance of offshore structural framing

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This review of the use of nonlinear ultimate strength (pushover) analyses in determining performance measures of tubular framed structures has been prepared for the Health and Safety Executive (HSE) by BOMEL Limited. An in-house state-of-the-art package (SAFJAC), developed over the last decade in parallel with experimental investigations, was used to analyse a variety of frames representative of platforms in the UK Sector of the North Sea. Ultimate strength analysis of offshore structures has increasingly become used to assess the integrity of various design configurations against extreme and accidental loading. It has also been used to determine the safety of existing offshore structures in view of updated environmental and structural data or changing operational requirements. It is now also being adopted to determine the criticality of members within the structural system and to assess various inspection and repair schemes. (author)

  17. High-strength concrete for Peacekeeper facilities

    Science.gov (United States)

    Saucier, K. L.

    1984-03-01

    An investigation is described which was conducted to determine the processes and techniques required to produce portland-cement concrete with a compressive strength of 15,000 psi or greater using conventional concreting methods and equipment, and to develop physical property data on the mixtures. It was permitted that special materials and admixtures be used, but a requirement was set that the aggregates and cements be selected from those available in the Cheyenne, Wyoming, area. Results indicated that it is feasible to achieve the 15,000-psi compressive strengths but that workability may decrease over a 2-hour period, and this latter development should be studied under job conditions. It is recommended that: (1) all materials and procedures to be used on a specific project be tested in the laboratory for basic property information, and (2) selected mixtures be tested in the field under expected environmental conditions prior to actual job use.

  18. Cold-Drawn Bioabsorbable Ferrous and Ferrous Composite Wires: An Evaluation of Mechanical Strength and Fatigue Durability

    Science.gov (United States)

    Schaffer, Jeremy E.; Nauman, Eric A.; Stanciu, Lia A.

    2012-08-01

    Yield strengths exceeding 1 GPa with elastic strains exceeding 1 pct were measured in novel bioabsorbable wire materials comprising high-purity iron (Fe), manganese (Mn), magnesium (Mn), and zinc (Zn), which may enable the development of self-expandable, bioabsorbable, wire-based endovascular stents. The high strength of these materials is attributed to the fine microstructure and fiber textures achieved through cold drawing techniques. Bioabsorbable vascular stents comprising nutrient metal compositions may provide a means to overcome the limitations of polymer-based bioabsorbable stents such as excessive strut thickness and poor degradation rate control. Thin, 125- μm wires comprising combinations of ferrous alloys surrounding a relatively anodic nonferrous core were manufactured and tested using monotonic and cyclic techniques. The strength and durability properties are tested in air and in body temperature phosphate-buffered saline, and then they were compared with cold-drawn 316L stainless steel wire. The antiferromagnetic Fe35Mn-Mg composite wire exhibited more than 7 pct greater elasticity (1.12 pct vs 1.04 pct engineering strain), similar fatigue strength in air, an ultimate strength of more than 1.4 GPa, and a toughness exceeding 35 mJ/mm3 compared with 30 mJ/mm3 for 316L.

  19. Predicting Soil Strength with Remote Sensing Data

    Science.gov (United States)

    2010-09-01

    Air Flight Services, HyVista Corporation, and Cabras Marine Corporation. B. PURPOSE AND SCOPE The primary focus of the CNMI’10 experiment was...operated by the Cabras Marine Corporation. The vessel had a crew of about ten personnel to support the team and aid in the on-load and off-load of

  20. 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......-parameter Weibull (and Normal) distributions give the best fits to the data available, especially if tail fits are used whereas the LogNormal distribution generally gives poor fit and larger coefficients of variation, especially if tail fits are used....

  1. Postactivation Potentiation Biases Maximal Isometric Strength Assessment

    Directory of Open Access Journals (Sweden)

    Leonardo Coelho Rabello Lima

    2014-01-01

    Full Text Available Postactivation potentiation (PAP is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs. The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n=23 performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT, time to achieve it (tPTI, contractile impulse (CI, root mean square of the electromyographic signal during PTI (RMS, and rate of torque development (RTD, in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·m versus 248.9 ± 55.1 N·m, RTD (746 ± 152 N·m·s−1versus 727 ± 158 N·m·s−1, and RMS (59.1 ± 12.2% RMSMAX  versus 54.8 ± 9.4% RMSMAX were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 ms versus 2784 ± 1226 ms. We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.

  2. High toughness-high strength iron alloy

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1980-01-01

    An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

  3. Evaluation of concrete mechanical strength through porosity

    Directory of Open Access Journals (Sweden)

    Olivares, M.

    2004-03-01

    Full Text Available The increasing on voids or pores in any material - if the rest of characteristics remains equal -always causes a decrease in their mechanical strength since the ratio volume/resistant mass is lower Following all these fact a well known conclusion rises: there is a relationship between compacity/porosity and mechanical strengths. The purpose of this research is to establish a new possible correlation between both concrete properties with independence of the proportions, type of cement, size of grain, age, use. etc. So it can be concluded that the results of this research allow the engineer or architect in charge of a restoration or reparation to determine the compression strength of a concrete element. A first step is to determine the porosity through a rather short number of tests. Subsequently, compression strength will be obtained applying just a mathematical formula.

    El aumento de huecos o poros de cualquier material, lo mismo que en otras circunstancias, redunda siempre en una merma de sus resistencias mecánicas, al haber menor volumen-masa resistente. En consecuencia, puede deducirse, que hay una relación entre la compacidad/porosidad y las resistencias mecánicas. En el presente trabajo se estudia una posible correlación entre ambas propiedades del hormigón con independencia de su dosificación, tipo de cemento, granulometría, edad, uso, etc. Las conclusiones obtenidas en la presente investigación permiten al técnico, encargado de una restauración o rehabilitación, determinar la resistencia a compresión de un elemento de hormigón, una vez hallada, de una forma sencilla, la porosidad de una muestra no muy voluminosa, mediante la aplicación de una simple fórmula matemática.

  4. Strength in Cognitive Self-Regulation

    OpenAIRE

    2013-01-01

    Failures in self-regulation are predictive of adverse cognitive, academic and vocational outcomes, yet the interplay between cognition and self-regulation failure remains elusive. Two experiments tested the hypothesis that lapses in self-regulation, as predicted by the strength model, can be induced in individuals using cognitive paradigms and whether such failures are related to cognitive performance. In Experiments 1, the stop-signal task (SST) was used to show reduced behavioral inhibition...

  5. Indoor field strength prediction based on FMM

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-bin; ZHANG Ye-rong

    2006-01-01

    In this article, the fast multipole method (FMM) is applied to analyze the field strength of an ultra-wideband (UWB)signal. Small coverage of UWB communication systems and high efficiency of the algorithm make it possible to calculate the amplitude of electric field accurately. A homogeneous dielectric body and a multilayered dielectric object are studied. The computational results obtained by applying the FMM agree well with those obtained by applying the method of moments (MoM).

  6. Olefin metathesis in air

    Directory of Open Access Journals (Sweden)

    Lorenzo Piola

    2015-10-01

    Full Text Available Since the discovery and now widespread use of olefin metathesis, the evolution of metathesis catalysts towards air stability has become an area of significant interest. In this fascinating area of study, beginning with early systems making use of high oxidation state early transition metal centers that required strict exclusion of water and air, advances have been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance.

  7. Air/Water Purification

    Science.gov (United States)

    1992-01-01

    After 18 years of research into air/water pollution at Stennis Space Center, Dr. B. C. Wolverton formed his own company, Wolverton Environmental Services, Inc., to provide technology and consultation in air and water treatment. Common houseplants are used to absorb potentially harmful materials from bathrooms and kitchens. The plants are fertilized, air is purified, and wastewater is converted to clean water. More than 100 U.S. communities have adopted Wolverton's earlier water hyacinth and artificial marsh applications. Catfish farmers are currently evaluating the artificial marsh technology as a purification system.

  8. Olefin metathesis in air

    Science.gov (United States)

    Piola, Lorenzo; Nahra, Fady

    2015-01-01

    Summary Since the discovery and now widespread use of olefin metathesis, the evolution of metathesis catalysts towards air stability has become an area of significant interest. In this fascinating area of study, beginning with early systems making use of high oxidation state early transition metal centers that required strict exclusion of water and air, advances have been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance. PMID:26664625

  9. Clean Air and Water

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    The air we breathe and the water we drink are both vital components of our health. Nevertheless, bacteria, pollutants, and other contaminates can alter life-giving air and water into health-threatening hazards. Learn about how scientists at the Centers for Disease Control and Prevention work to protect the public from air and water-related health risks.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  10. Air Quality Monitoring Programme

    DEFF Research Database (Denmark)

    Kemp, K.; Palmgren, F.

    The air quality in Danish cities has been monitored continuously since 1982 within the Danish Air Quality (LMP) network. The aim has been to follow the concentration levels of toxic pollutants in the urban atmosphere and to provide the necessary knowledge to assess the trends, to perform source...... apportionment, and to evaluate the chemical reactions and the dispersion of the pollutants in the atmosphere. In 2002 the air quality was measured in four Danish cities and at two background sites. NO2 and PM10 were at several stations found in concentrations above the new EU limit values, which the Member...

  11. Mid-air Acrobatics

    Institute of Scientific and Technical Information of China (English)

    LlU FENG'AN

    2011-01-01

    On September 1 two new aerobatic demonstration teams,theSky Wing and the Red Falcon,debuted at an air show held in Changchun,capital of northeast China's Jilin Province.The show was staged at a ceremony held by the Aviation University of the People's Liberation Army (PLA) Air Force.Also performing at the show was the 50-year-old Bayi aerobatic demonstration team.The teams demonstrated their superlative flying skills,which showcase the quality of the air force's rigorous pilot training.

  12. The theoretical tensile strength of fcc crystals predicted from shear strength calculations

    Science.gov (United States)

    Černý, M.; Pokluda, J.

    2009-04-01

    This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for \\langle 001\\rangle and \\langle 111\\rangle loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for \\langle 110\\rangle loading almost match the stresses related to tensile instability.

  13. Acute effects of partial-body cryotherapy on isometric strength: maximum handgrip strength evaluation.

    Science.gov (United States)

    De Nardi, M; Pizzigalli, L; Benis, R; Caffaro, F; Cremasco, M Micheletti

    2017-01-20

    The aim of the study was to evaluate the influence of a single partial-body cryotherapy (PBC) session on the maximum handgrip strength (JAMAR Hydraulic Hand dynamometer). Two hundred healthy adults were randomized into a PBC group and a control group (50 males and 50 females in each group). After the initial handgrip strength test (T0), the experimental group performed a 150 seconds session of PBC (temperature range between -130 and -160 °C), whilst the control group stayed in a thermo neutral room (22.0 ± 0.5 °C). Immediately after, both groups performed another handgrip strength test (T1). Data underlined that both groups showed an increase in handgrip strength values, especially the experimental group (Control: T0=39.48 kg, T1=40.01 kg; PBC: T0=39.61 kg, T1=41.34 kg). The analysis reported also a statistical effect related to gender (F=491.99, Pstrength values compared with males (females=30.43 kg, males=52.27 kg). Findings provide the first evidence that a single session of PBC leads to the improvement of muscle strength in healthy people. The results of the study implies that PBC could be performed also before a training session or a sport competition, to increase hand isometric strength.

  14. Strength Optimization of Thermally Bonded Spunbond Nonwovens

    Directory of Open Access Journals (Sweden)

    Nataliya Fedorova, Ph.D

    2007-04-01

    Full Text Available Recent research on all aspects of thermally point bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding and the resultant deterioration of the mechanical properties of the nonwoven materials. This paper addresses how one may use a bicomponent fiber technology to overcome the shortcomings of the thermal bonding and obtain high strength spunbond fabrics. In particular, we present the utility of islands-in-the-sea (I/S bicomponent fibers for optimizing the strength of thermally bonded fabrics. To examine the role of various bonding temperatures on the fabric performance, pre-consolidated webs were formed and subsequently, thermally bonded. Thus, any influence introduced by potential variations in the structure was minimized. Point-bonded bicomponent samples made up of nylon-6 (N6 as the islands and low density polyethylene (PE as the sea showed great promise with respect to their mechanical properties, suggesting that the use of bicomponent fibers can be beneficial for strength optimization of thermally bonded spunbond nonwovens.

  15. ROSETTA lander Philae - soil strength analysis

    Science.gov (United States)

    Roll, Reinhard; Witte, Lars; Arnold, Walter

    2016-12-01

    The landing of Philae, the lander of ESA's ROSETTA-mission, on November 12th 2014 on Comet 67P/Churyumov-Gerasimenko, was planned as a descent with passive landing activating a damper system and anchoring by harpoons at touch-down. The lander was not fixed to the ground at touch-down due to failing harpoons. The lander damper, however, was actuated for a length of 42.6 mm with a maximal speed of 0.08 m/s, while the lander speed was 1 m/s. Based on the damper data and a detailed mechanical model of Philae, an estimate can be made for the forces acting and the energy dissipated at touch-down inside the lander and the energy dissipated by ground penetration. The forces acting at ground penetration provide constraints on the mechanical strength of the soil. Two different soil models are investigated. Assuming constant compressive strength σ, one obtains σ ≈ 2 kPa. Assuming an increasing σs strength with penetration depth with results in σs = 3 kPa/m fits the damper data best.

  16. Electric Monopole Transition Strengths in 62Ni

    Science.gov (United States)

    Evitts, L. J.; Garnsworthy, A. B.; Kibédi, T.; Moukaddam, M.; Alshahrani, B.; Eriksen, T. K.; Holt, J. D.; Hota, S. S.; Lane, G. J.; Lee, B. Q.; McCormick, B. P.; Palalani, N.; Reed, M. W.; Stroberg, S. R.; Stuchbery, A. E.

    2016-09-01

    Excited states in 62Ni were populated with a (p, p') reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0), were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77-34+23 × 10-3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0) value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0) values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0) value for the 22+ to 21+ transition.

  17. Electric Monopole Transition Strengths in 62Ni

    Directory of Open Access Journals (Sweden)

    Evitts L. J.

    2016-01-01

    Full Text Available Excited states in 62Ni were populated with a (p, p’ reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0, were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77−34+23 × 10−3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0 value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0 values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0 value for the 22+ to 21+ transition.

  18. Interlimb coupling strength scales with movement amplitude.

    Science.gov (United States)

    Peper, C Lieke E; de Boer, Betteco J; de Poel, Harjo J; Beek, Peter J

    2008-05-23

    The relation between movement amplitude and the strength of interlimb interactions was examined by comparing bimanual performance at different amplitude ratios (1:2, 1:1, and 2:1). For conditions with unequal amplitudes, the arm moving at the smaller amplitude was predicted to be more strongly affected by the contralateral arm than vice versa. This prediction was based on neurophysiological considerations and the HKB model of coupled oscillators. Participants performed rhythmic bimanual forearm movements at prescribed amplitude relations. After a brief mechanical perturbation of one arm, the relaxation process back to the initial coordination pattern was examined. This analysis focused on phase adaptations in the unperturbed arm, as these reflect the degree to which the movements of this arm were affected by the coupling influences stemming from the contralateral (perturbed) arm. The thus obtained index of coupling (IC) reflected the relative contribution of the unperturbed arm to the relaxation process. As predicted IC was larger when the perturbed arm moved at a larger amplitude than did the unperturbed arm, indicating that coupling strength scaled with movement amplitude. This result was discussed in relation to previous research regarding sources of asymmetry in coupling strength and the effects of amplitude disparity on interlimb coordination.

  19. Dipole strength distribution of {sup 50}Ti

    Energy Technology Data Exchange (ETDEWEB)

    Gayer, Udo; Beck, Tobias; Beller, Jacob; Mertes, Laura; Pai, Haridas; Pietralla, Norbert; Ries, Philipp; Romig, Christopher; Werner, Volker; Zweidinger, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany)

    2015-07-01

    A first nuclear resonance fluorescence (NRF) experiment with a 68% isotopically enriched {sup 50}Ti target has been performed at the superconducting Darmstadt electron linear accelerator S-DALINAC to investigate particle-bound dipole excitations in this nucleus. The target was irradiated with an unpolarized bremsstrahlung photon beam at endpoint energies of 7.5 MeV and 9.7 MeV. The observed excited states are analyzed with respect to their excitation energies, spin quantum numbers and transition strengths. A complementary NRF experiment with polarized photons will be conducted at the High Intensity gamma-ray Source in Durham, NC, USA to determine the polarity of the dipole transitions. Data will be analyzed with regard to the Pygmy Dipole Resonance, a weakly-collective electric dipole excitation which starts to form in nuclei of this mass region. The measured transition strengths will be compared to microscopic calculations in the quasiparticle-phonon model. The investigation of the magnetic dipole strength distribution will focus on strong spin-flip transitions between the p,f spin-orbit partners expected in the nuclear shell model. First results of the measurements and the evaluation will be presented and discussed.

  20. Measuring Strength of Motivation for Medical School

    Directory of Open Access Journals (Sweden)

    Marja GH Nieuwhof

    2004-01-01

    Full Text Available Purpose. Students vary in their strength of motivation to start and pursue medical training. This study was conducted to investigate the psychometric properties of a Strength of Motivation for Medical School (SMMS questionnaire. Method. The questionnaire was designed using an iterative method. The instrument was applied to medical students (N= 296 at the start of medical school and to potential applicants (N= 147. The stability of the concept over a six month’s time and associations with other motivation measures were studied. A separate group of potential applicants and their parents (N= 169 were asked to validate the items of the questionnaire. Results. Cronbach’s alpha reliability of .79 was found. Test-retest reliability of SMMS-scores with a six months interval was .71. Little to no association with specific dimensions of motivation was found, except for a negative correlation with ‘ambivalence towards studying’. SMMS-scores were associated with potential applicants’ plans to apply for medical school (Spearman’s rho .65 and differentially with potential applicants’ and their parents’ judgements of item validities (.13 to .57. Conclusions. The SMMS-questionnaire appears to be a reliable and valid instrument to measure strength of motivation for medical training in students who have just entered medical school. It may be used to evaluate the validity of selection procedures and to identify associated variables that could be used in selection procedures.