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1

Impurity temperature correction factors for the transmission grating spectrometer in the TJ-II stellarator  

SciTech Connect

Impurity ion temperature and velocity profiles are obtained across plasmas in the TJ-II stellarator by performing charge-exchange recombination spectroscopy with a diagnostic neutral beam injector. For this, a tridirectional (toroidal plus two poloidal opposing views) multichannel spectroscopic diagnostic, incorporating 12-way fiber arrays, a compact f/1.8 spectrograph, and a back-illuminated CCD, permits Doppler line shifts and widths (of the C VI line at 529.05 nm) to be determined with 1-2 cm spatial resolution. For good photon counting statistics under Li-coated wall conditions, 600 {mu}m diameter fibers collect and transmit light to curved 100 {mu}m wide input slits. When calibrated with a neon pencil lamp this entrance slit width results in a non-Gaussian instrumental function that, if not handled correctly, can result in systematically underestimated impurity temperatures. Here we develop and present correction factors for this effect for a range of conditions.

Arevalo, J.; McCarthy, K. J.; Carmona, J. M.; Fontdecaba, J. M. [Laboratorio Nacional de Fusion, Association Euratom-Ciemat, E-28040 Madrid (Spain)

2010-10-15

2

Temperature Corrected Bootstrap Algorithm  

NASA Technical Reports Server (NTRS)

A temperature corrected Bootstrap Algorithm has been developed using Nimbus-7 Scanning Multichannel Microwave Radiometer data in preparation to the upcoming AMSR instrument aboard ADEOS and EOS-PM. The procedure first calculates the effective surface emissivity using emissivities of ice and water at 6 GHz and a mixing formulation that utilizes ice concentrations derived using the current Bootstrap algorithm but using brightness temperatures from 6 GHz and 37 GHz channels. These effective emissivities are then used to calculate surface ice which in turn are used to convert the 18 GHz and 37 GHz brightness temperatures to emissivities. Ice concentrations are then derived using the same technique as with the Bootstrap algorithm but using emissivities instead of brightness temperatures. The results show significant improvement in the area where ice temperature is expected to vary considerably such as near the continental areas in the Antarctic, where the ice temperature is colder than average, and in marginal ice zones.

Comiso, Joey C.; Zwally, H. Jay

1997-01-01

3

Profile correction to electron temperature and enhancement factor in soft x-ray pulse-height-analysis measurements in tokamaks  

SciTech Connect

Because soft x-ray pulse-height-analysis (PHA) spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. Assuming that the profile Ansatz for the electron temperature and density is of the form n/sub eo/(1-(ra)/sup 2/)/sup ..cap alpha../ and kT/sub eo/(1--(ra)/sup 2/)/sup ..beta../, we obtain the correction factors for the electron temperature and the enhancement factor as a function of the profile coefficients ..cap alpha.. and ..beta.. and the energy at which the evaluation was made. The corrected values of the temperature are typically between 1 to 10% higher than the values derived from the raw chordal spectra. We also correct the measured radiation intensity for the profile effects. Finally, the spectrum distortion due to pulse pile-up effects is evaluated. A set of curves is given from which the distortion of the spectrum can be obtained, if the electron temperature, the Be or Al filter thickness, and the electronic parameters of the acquisition system are known. 7 refs., 23 figs.

Sesnic, S.; Diesso, M.; Hill, K.; Holland, A.; Pohl, F.

1988-04-01

4

Estimating changes in mean body temperature for humans during exercise using core and skin temperatures is inaccurate even with a correction factor.  

PubMed

Changes in mean body temperature (DeltaT(b)) estimated by the traditional two-compartment model of "core" and "shell" temperatures and an adjusted two-compartment model incorporating a correction factor were compared with values derived by whole body calorimetry. Sixty participants (31 men, 29 women) cycled at 40% of peak O(2) consumption for 60 or 90 min in the Snellen calorimeter at 24 or 30 degrees C. The core compartment was represented by esophageal, rectal (T(re)), and aural canal temperature, and the shell compartment was represented by a 12-point mean skin temperature (T(sk)). Using T(re) and conventional core-to-shell weightings (X) of 0.66, 0.79, and 0.90, mean DeltaT(b) estimation error (with 95% confidence interval limits in parentheses) for the traditional model was -95.2% (-83.0, -107.3) to -76.6% (-72.8, -80.5) after 10 min and -47.2% (-40.9, -53.5) to -22.6% (-14.5, -30.7) after 90 min. Using T(re), X = 0.80, and a correction factor (X(0)) of 0.40, mean DeltaT(b) estimation error for the adjusted model was +9.5% (+16.9, +2.1) to -0.3% (+11.9, -12.5) after 10 min and +15.0% (+27.2, +2.8) to -13.7% (-4.2, -23.3) after 90 min. Quadratic analyses of calorimetry DeltaT(b) data was subsequently used to derive best-fitting values of X for both models and X(0) for the adjusted model for each measure of core temperature. The most accurate model at any time point or condition only accounted for 20% of the variation observed in DeltaT(b) for the traditional model and 56% for the adjusted model. In conclusion, throughout exercise the estimation of DeltaT(b) using any measure of core temperature together with mean skin temperature irrespective of weighting is inaccurate even with a correction factor customized for the specific conditions. PMID:17495122

Jay, Ollie; Reardon, Francis D; Webb, Paul; Ducharme, Michel B; Ramsay, Tim; Nettlefold, Lindsay; Kenny, Glen P

2007-08-01

5

ART and SIRT correction factors in geotomography  

NASA Astrophysics Data System (ADS)

The ART and SIRT image reconstruction techniques are introduced and a correction factor which provides high resolution images is presented. The techniques were tested using synthetic measurements. In order to examine the manner in which each reconstruction progresses, the Euclidean distance for the reconstructions were plotted, versus iteration number. Results indicate that ART produces better reconstructed profiles than the SIRT (using identical correction factors).

Balanis, C. A.; Hill, H. W.; Freeland, K. A.

1983-04-01

6

Effective Temperature Scale and Bolometric Corrections  

NASA Astrophysics Data System (ADS)

The conversion from an observational quantity, such as the color index or the spectral type, to the effective temperature (Teff) of a star is known as the effective TEMPERATURE SCALE. Bolometric corrections are required in the calculation of the luminosity of a star if the flux from the star has not been observed over the entire ELECTROMAGNETIC SPECTRUM....

Gray, R.; Murdin, P.

2000-11-01

7

Nonideality Correction Factors for Adsorbates  

Microsoft Academic Search

The values of the nonideality factor, ?, obtained by P. H. Emmett and S. Brunauer, (J. Am. Chem. Soc.59,1553 (1937)) with the aid of the van der Waals equation of state for various adsorbates, and which are routinely utilized in adsorption experiments, are valid only for nonpolar gases such as nitrogen, argon, and oxygen. On the other hand, for most

A. Venkatraman; L. T. Fan; W. P. Walawender

1996-01-01

8

49 CFR 325.73 - Microphone distance correction factors. 1  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Microphone distance correction factors. 1 325... Correction Factors § 325.73 Microphone distance correction factors. 1 1...75. If the distance between the microphone location point and the...

2010-10-01

9

49 CFR 325.73 - Microphone distance correction factors. 1  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Microphone distance correction factors. 1 325... Correction Factors § 325.73 Microphone distance correction factors. 1 1...75. If the distance between the microphone location point and the...

2009-10-01

10

49 CFR 325.75 - Ground surface correction factors. 1  

Code of Federal Regulations, 2013 CFR

...Ground surface correction factors. 1 325.75 Section... FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT...EMISSION STANDARDS Correction Factors § 325.75 Ground surface correction factors. 1 1 Table 1,...

2013-10-01

11

Scale-factor corrections in large ring lasers  

NASA Astrophysics Data System (ADS)

The authors report on fluctuations of the geometric scale factor of a very large ring laser situated 30 m underground in the Cashmere Cavern in Christchurch (New Zealand). Variations in temperature and atmospheric pressure cause thermoelastic deformations to the cavern, which lead to changes of the area and perimeter of the ring laser structure. In situ beam monitoring has been used to partially correct for these effects.

Pritsch, B.; Schreiber, K. U.; Velikoseltsev, A.; Wells, J.-P. R.

2007-08-01

12

A novel single-phase power factor correction scheme  

Microsoft Academic Search

A single-phase power factor correction scheme is proposed based on the power flow analysis. It is found that the conventional power factor correction (PFC) circuit must be designed to handle the rated power, although its purpose is only for power factor correction. With the proposed scheme, the PFC circuit is in parallel with the major power flow path, thus reducing

Yimin Jiang; Fred C. Lee; Guichao Hua; Wei Tang

1993-01-01

13

Elevation correction factor for absolute pressure measurements  

NASA Technical Reports Server (NTRS)

With the arrival of highly accurate multi-port pressure measurement systems, conditions that previously did not affect overall system accuracy must now be scrutinized closely. Errors caused by elevation differences between pressure sensing elements and model pressure taps can be quantified and corrected. With multi-port pressure measurement systems, the sensing elements are connected to pressure taps that may be many feet away. The measurement system may be at a different elevation than the pressure taps due to laboratory space or test article constraints. This difference produces a pressure gradient that is inversely proportional to height within the interface tube. The pressure at the bottom of the tube will be higher than the pressure at the top due to the weight of the tube's column of air. Tubes with higher pressures will exhibit larger absolute errors due to the higher air density. The above effect is well documented but has generally been taken into account with large elevations only. With error analysis techniques, the loss in accuracy from elevation can be easily quantified. Correction factors can be applied to maintain the high accuracies of new pressure measurement systems.

Panek, Joseph W.; Sorrells, Mark R.

1996-01-01

14

A Multipoint Correction Method for Environmental Temperature Changes in Airborne Double-Antenna Microwave Radiometers  

PubMed Central

This manuscript describes a new type Ka-band airborne double-antenna microwave radiometer (ADAMR) designed for detecting atmospheric supercooled water content (SCWC). The source of the measurement error is investigated by analyzing the model of the system gain factor and the principle of the auto-gain compensative technique utilized in the radiometer. Then, a multipoint temperature correction method based on the two-point calibration method for this radiometer is proposed. The multipoint temperature correction method can eliminate the effect of changes in environmental temperature by establishing the relationship between the measurement error and the physical temperatures of the temperature-sensitive units. In order to demonstrate the feasibility of the correction method, the long-term outdoor temperature experiment is carried out. The multipoint temperature correction equations are obtained by using the least square regression method. The comparison results show that the measuring accuracy of the radiometer can be increased more effectively by using the multipoint temperature correction method.

Sun, Jian; Zhao, Kai; Jiang, Tao

2014-01-01

15

An uncertainty analysis of the spectral correction factor  

Microsoft Academic Search

Whenever a photovoltaic device is evaluated with respect to a reference spectrum, there is a spectral mismatch error. The photocurrent can be corrected for this error with a spectral correction factor, as is routinely done for primary and secondary terrestrial reference solar cell calibrations at laboratories throughout the world. The spectral correction factor has also been used to accurately measure

H. Field; K. Emery

1993-01-01

16

Development of a Pressure Sensitive Paint System with Correction for Temperature Variation  

NASA Technical Reports Server (NTRS)

Pressure Sensitive Paint (PSP) is known to provide a global image of pressure over a model surface. However, improvements in its accuracy and reliability are needed. Several factors contribute to the inaccuracy of PSP. One major factor is that luminescence is temperature dependent. To correct the luminescence of the pressure sensing component for changes in temperature, a temperature sensitive luminophore incorporated in the paint allows the user to measure both pressure and temperature simultaneously on the surface of a model. Magnesium Octaethylporphine (MgOEP) was used as a temperature sensing luminophore, with the pressure sensing luminophore, Platinum Octaethylporphine (PtOEP), to correct for temperature variations in model surface pressure measurements.

Simmons, Kantis A.

1995-01-01

17

49 CFR 325.79 - Application of correction factors.  

Code of Federal Regulations, 2013 CFR

...application of correction factors to sound level measurement readings: (1) Example...vehicle generates a maximum observed sound level reading of 86 dB(A) during...acoustically hard. The corrected sound level generated by the motor...

2013-10-01

18

An Analysis of Ionization Correction Factors in Planetary Nebulae  

NASA Astrophysics Data System (ADS)

I will present here some of the results derived from our recent analysis of ionization correction factors (ICFs) in planetary nebulae (PNe). We compute an extensive grid of ~15000 photoionization models using the c10.00 version of Cloudy code (Ferland et al. 1998) that cover a wide range of effective temperatures, nebular radius, luminosities, and gas densities. We use both blackbodies and Rauch atmospheres as ionizing sources, and we calculate constant and non-constant density models as well as radiation-and matter-bounded models. We derive new ICFs for PNe and their associated uncertainties. I will discuss the differences with previous ICFs used in the literature.

Delgado-Inglada, G.

2014-04-01

19

Computer model generated density correction factors for gamma spectroscopy counting.  

PubMed

Using the calibration curve of a single reference source to infer activity levels in samples of different bulk density and/or elemental composition may yield inaccurate results by a gamma spectroscopy system. These inaccuracies are magnified when counting low energy photons, which interact primarily through the photoelectric effect. There have been numerous methods described to empirically derive density correction factors for various samples. An alternate solution is to theoretically derive density correction factors using a computer model. The computer model generated density correction factors for material such as sand, ilmenite, and polyester are in close agreement with published empirically derived density correction factors for these same materials. PMID:9003719

Darman, J J; Aldana, J P

1997-02-01

20

Resistance Moisture Meter Correction Factors for Four Tropical Wood Species.  

National Technical Information Service (NTIS)

Connection factors were determined for an electrical resistance-type moisture meter for African celtis (Celtis sp.), dahoma (Piptadeniastrum africanum), ramon (Brosimun alicastrum), and danto (Vatairea lundellii). For all species, correction factors were ...

W. T. Simpson

1994-01-01

21

Neural networks to predict exosphere temperature corrections  

NASA Astrophysics Data System (ADS)

Precise orbit prediction requires a forecast of the atmospheric drag force with a high degree of accuracy. Artificial neural networks are universal approximators derived from artificial intelligence and are widely used for prediction. This paper presents a method of artificial neural networking for prediction of the thermosphere density by forecasting exospheric temperature, which will be used by the semiempirical thermosphere Drag Temperature Model (DTM) currently developed. Artificial neural network has shown to be an effective and robust forecasting model for temperature prediction. The proposed model can be used for any mission from which temperature can be deduced accurately, i.e., it does not require specific training. Although the primary goal of the study was to create a model for 1 day ahead forecast, the proposed architecture has been generalized to 2 and 3 days prediction as well. The impact of artificial neural network predictions has been quantified for the low-orbiting satellite Gravity Field and Steady-State Ocean Circulation Explorer in 2011, and an order of magnitude smaller orbit errors were found when compared with orbits propagated using the thermosphere model DTM2009.

Choury, Anna; Bruinsma, Sean; Schaeffer, Philippe

2013-10-01

22

Spectral and temperature correction of silicon photovoltaic solar radiation detectors  

Microsoft Academic Search

Silicon photovoltaic sensors are an inexpensive alternative to standard thermopile sensors for the measurement of solar radiation. However, their temperature and spectral response render them less accurate for global horizontal irradiance and unsuitable for direct beam and diffuse horizontal irradiance unless they can be reliably corrected. A correction procedure for the rotating shadowband radiometer, which measures all three components, based

J. J. Michalsky; R. Perez; L. Harrison; B. A. LeBaron

1991-01-01

23

Estimation of Ambient Radiation Temperature for Emissivity-Corrected Thermography.  

National Technical Information Service (NTIS)

A non-contact method for the measurement of emissivity, and emissivity-corrected temperatures has been developed, where the ambient radiation-temperature is changed in a discontinuous way. When the ambient radiation-temperature is unchanged quickly, so th...

K. Otsuka S. Okada T. Togawa

2001-01-01

24

Temperature corrections for the VIZ and Vaisala raddiosondes  

SciTech Connect

The National Weather Service VIZ radiosonde and the Vaisala RS-80 radiosondes are used worldwide to obtain upper-air measurements of atmospheric temperature and moisture. The temperature measured by each sensor is not equal to the atmospheric temperature due to solar and infrared irradiation of the sensor, heat conduction to the sensor from is attachment points, and radiation emitted by the sensor. Presently, only the RS-80 radiosonde applies corrections to the sensor temperature to compensate for these heating sources, and this correction is only considered to be a function of solar angle and pressure. Temperature correction models VIZCOR (VIZ sonde) and VAICOR (Vaisala RS-80 sonde) have been developed that derive the atmospheric temperature from the sensor temperature, taking into account all significant environmental processes that influence the heat transfer to the sensor. These models have been validated by comparing their corrected profiles with atmospheric temperature profiles derived from the NASA multithermistor radiosonde. All three radiosondes were flown on the same balloon during the potential reference radiosonde intercomparison. Excellent agreement has been found between all profiles up to an altitude of 30 km. Since the significant error sources in the VIZCOR, VAICOR, and multithermistor techniques are largely independent, agreement between all profiles implies that the corrected sensor profiles are providing an unbiased estimate of the true atmospheric temperature. 17 refs., 17 figs.

Luers, J.K. [Univ. of Dayton Research Institute, OH (United States)] [Univ. of Dayton Research Institute, OH (United States); Eskridge, R.E. [National Oceanic and Atmospheric Administration, Asheville, NC (United States)] [National Oceanic and Atmospheric Administration, Asheville, NC (United States)

1995-06-01

25

Pseudophakic correction factors for optical biometry  

Microsoft Academic Search

Introduction: The IOLMaster of Carl Zeiss Jena, which has recently become available, is a combined instrument for biometry and intraocular lens (IOL) planning for cataract surgery utilizing partial coherence interferometry for measuring axial length. Whereas measurement data from classical ultrasound biometry, e.g. in pseudophakic eyes, need to be corrected by +0.4 to -0.8 mm - depending on the lens material

Wolfgang Haigis

2001-01-01

26

Correction of high-frequency noise-temperature inaccuracies  

NASA Technical Reports Server (NTRS)

Deep-space mission data rates to Earth are limited by the system operating noise-temperature (T(sub op)) performance of the DSN. This article addresses some of the techniques and definitions used for measuring and reporting the effective noise temperature of receivers (Te) and T(sub op) of the DSN's ground receiving systems. Calibration loads are used to measure T(sub op) of the DSN antennas. At 32 GHz, a calibration load cooled to 2-K physical temperature requires a correction of 0.67 K to determine the noise temperature. Using corrected noise temperature for the calibration loads results in the correct values for T(sub op) such that the total system noise power can be defined by Pn = kT(sub op) B, as required for DSN telecommunications design control tables. T(sub op) and Te should not be converted to equivalent physical temperatures.

Stelzreid, C. T.

1992-01-01

27

Temperature-Corrected Model of Turbulence in Hot Jet Flows  

NASA Technical Reports Server (NTRS)

An improved correction has been developed to increase the accuracy with which certain formulations of computational fluid dynamics predict mixing in shear layers of hot jet flows. The CFD formulations in question are those derived from the Reynolds-averaged Navier-Stokes equations closed by means of a two-equation model of turbulence, known as the k-epsilon model, wherein effects of turbulence are summarized by means of an eddy viscosity. The need for a correction arises because it is well known among specialists in CFD that two-equation turbulence models, which were developed and calibrated for room-temperature, low Mach-number, plane-mixing-layer flows, underpredict mixing in shear layers of hot jet flows. The present correction represents an attempt to account for increased mixing that takes place in jet flows characterized by high gradients of total temperature. This correction also incorporates a commonly accepted, previously developed correction for the effect of compressibility on mixing.

Abdol-Hamid, Khaled S.; Pao, S. Paul; Massey, Steven J.; Elmiligui, Alaa

2007-01-01

28

Correcting for the Temperature Dependence of ACIS Charge Transfer Inefficiency  

NASA Astrophysics Data System (ADS)

The spectral resolution of the ACIS CCDs is substantially improved by a charge transfer inefficiency (CTI) correction algorithm included in acis_process_events. However, the behavior of the charge traps that cause CTI is temperature dependent: warmer-than-nominal focal plane temperatures reduce the effectiveness of the correction algorithm. As the insulation on the exterior of the SIM and the ACIS radiator shade have aged, the surfaces around the ACIS focal plane and radiator have become warmer, leading to FP temperatures which are sometimes a few degrees warmer than desired, particularly for observations done at spacecraft pitch angles greater than 140 degrees. The ACIS team successfully reduced average focal plane temperatures by shutting off the detector housing heater in April 2008 and a heater on the SIM was turned off in August 2009 providing additional margin, but many warm observations exist in the archive, and observations done at "tail-Sun" attitudes still often have warm focal plane temperatures. Here we review the temperature dependence of ACIS performance and present a temperature-dependent CTI correction algorithm, which we have implemented as contributed software designed to work with current CALDB products and CIAO tools. We show examples using this software to CTI-correct warm ACIS observations.

Posson-Brown, Jennifer; Grant, C.; Allen, G.; Plucinsky, P.; Edgar, R.

2010-02-01

29

Finite-temperature and -density corrections to electroweak processes  

SciTech Connect

We present the calculations for the first-order radiative corrections to the electroweak processes at finite temperature and density. As a typical example, the processes {ital Z}{sup 0}{r arrow}{ital l}{sup +}{ital l{minus}} are discussed in detail at QED temperatures. It is noted that the calculations are somewhat different from those in QED. The helicity flipping changes the decay rate in the background of chiral fermions whereas, in the presence of hot photons only, the radiative corrections are similar to those for {ital H}{sup 0}{r arrow}{ital e}{sup +}{ital e{minus}} in QED.

Masood, S.S.; Qader, M. (Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan))

1992-12-01

30

Spectral and temperature correction of silicon photovoltaic solar radiation detectors  

SciTech Connect

Silicon photovoltaic sensors are an inexpensive alternative to standard thermopile sensors for the measurement of solar radiation. However, their temperature and spectral response render them less accurate for global horizontal irradiance and unsuitable for direct beam and diffuse horizontal irradiance unless they can be reliably corrected. A correction procedure for the rotating shadowband radiometer, which measures all three components, based on a three-way parameterization of the solar position and sky conditions is proposed. After correction, root-mean-square errors for the global and diffuse horizontal irradiance and the direct normal irradiance are about 10, 12, and 13 W/m{sup 2} in comparison with coincident, 5-minute thermopile measurements. While the numerical results are specific to the rotating shadowband instrument, the correction algorithm should apply universally.

Michalsky, J.J.; Perez, R.; Harrison, L. (State Univ. of New York, Albany (United States)); LeBaron, B.A. (Pacific Northwest Lab., Richland, WA (United States))

1991-01-01

31

Power factor correction with flyback converter employing charge control  

Microsoft Academic Search

The charge control concept is applied to a flyback power converter for the purpose of power factor correction (PFC). Using charge control, a flyback converter can operate in continuous conduction-mode (CCM) with unity power factor. The simplicity of the flyback circuit is maintained and the power handling capacity is increased. The properties of charge control related to flyback PFC application

W. Tang; Y. Jiang; G. C. Hua; F. C. Lee; I. Cohen

1993-01-01

32

Improved SIRT correction factors and redistribution in geotomography  

NASA Astrophysics Data System (ADS)

In this paper revised correction factors are introduced which improve the profile of a geophysical environment reconstructed using the Simultaneous Iterative Reconstruction Technique (SIRT). These factors are based not only on the distances a given ray passes through the cells, as was assumed in the past, but also on the existing values (from a previous iteration) of the electrical properties of the cells through which a ray traverses. In addition, redistribution of the correction factors is utilized whenever the updated value of the electrical parameter of a given cell falls below a physically realizable or an a priori minimum value.

Balanis, C. A.; Hill, H. W.; Freeland, K. A.

33

Power Factor Correction Using Magnetic Energy Recovery Current Switches  

NASA Astrophysics Data System (ADS)

In this paper, we propose a Magnetic Energy Recovery Switch (MERS). The switch consists of four MOSFET elements and one capacitor. A power factor improvement is automatically possible regardless of the impedance and power frequency of the load by synchronized switching of MERS with a power supply. MERS itself generates voltage and compensates for the inductance voltage unlike a conventional series capacitor, so that another dc power supply is not needed. An experiment was carried out to demonstrate the automatic correction of the power factor. We can also expect energy saving of electromachies such as an electric motor by the power factor correction with MERS.

Takaku, Taku; Isobe, Takanori; Narushima, Jun; Tsutsui, Hiroaki; Shimada, Ryuichi

34

Four point probe geometry modified correction factor for determining resistivity  

NASA Astrophysics Data System (ADS)

The four-point probe technique is well known for its use in determining sheet resistance and resistivity (or effective resistivity) of thin films. Using a standard four-point probe setup, relatively large area samples are required. The convention is that the distance from any probe in the probe arrangement should be at least ten times the probe spacing from the sample boundary in order to use the fixed correction factor. In this paper we show, using computer modelling, how accurate measurements can be made using appropriate correction factors for samples that are either small or of any thickness. For the significant extent of variations used, the correction factor does not vary significantly.

Algahtani, Fahid; Thulasiram, Karthikram B.; Nasir, Nashrul M.; Holland, Anthony S.

2013-12-01

35

An EGSnrc investigation of correction factors for ion chamber dosimetry  

NASA Astrophysics Data System (ADS)

Radiation dosimetry is used to quantify the dose delivered during radiation therapy by using ionization chambers with several correction factors. Knowledge of these factors is needed at well below the 1% level in order to maintain the overall uncertainty on the reference dosimetry near 1-2%. The small magnitude of the corrections renders measurements very difficult. Monte Carlo calculations are widely used for this purpose, however they require very low statistical uncertainties. A new user-code, CSnrc, for the EGSnrc Monte Carlo system is described. CSnrc uses a correlated sampling variance reduction technique to reduce the uncertainty for dose ratio calculations. Compared to an existing EGSnrc user-code from which it was developed, CSnrc shows gains in efficiency of up to a factor of 64 and achieves much lower statistical uncertainties on correction factors than previously published. CSnrc is used to compute the central electrode correction factor, Pcel, in a broader range of beams than previously used and at the depths relevant to modern protocols. For photon beams, the CSnrc values compare well with the values used in dosimetry protocols whereas for electron beams, CSnrc shows up to a 0.2% correction for a graphite electrode, a correction currently ignored by dosimetry protocols. The difference from currently used values is slightly less for an aluminum electrode. CSnrc is also used to compute the wall correction factor, P wall. For cylindrical chambers in photon beams, the CSnrc calculations are compared to the currently used Almond-Svensson formalism and differ from this formalism by as much as 0.8%. The CSnrc values are used to explain some previously published experiments showing problems with Pwall . For electron beams, where dosimetry protocols assume a Pwall of unity, CSnrc calculations show a correction as large as 0.6%. For parallel-plate chambers, there is little information available regarding Pwall in photon beams. CSnrc shows corrections of over 2% for some chambers. In electron beams, Pwall has been assumed to be unity, despite previously published evidence suggesting otherwise. CSnrc shows that for some chambers at lower energies, Pwall is nearly 1.02.

Buckley, Lesley A.

36

Ionization correction factors for planetary nebulae - I. Using optical spectra  

NASA Astrophysics Data System (ADS)

We compute a large grid of photoionization models that covers a wide range of physical parameters and is representative of most of the observed planetary nebulae (PNe). Using this grid, we derive new formulae for the ionization correction factors (ICFs) of He, O, N, Ne, S, Ar, Cl, and C. Analytical expressions to estimate the uncertainties arising from our ICFs are also provided. This should be useful since these uncertainties are usually not considered when estimating the error bars in element abundances. Our ICFs are valid over a variety of assumptions such as the input metallicities, the spectral energy distribution of the ionizing source, the gas distribution, or the presence of dust grains. Besides, the ICFs are adequate both for large aperture observations and for pencil-beam observations in the central zones of the nebulae. We test our ICFs on a large sample of observed PNe that extends as far as possible in ionization, central star temperature, and metallicity, by checking that the Ne/O, S/O, Ar/O, and Cl/O ratios show no trend with the degree of ionization. Our ICFs lead to significant differences in the derived abundance ratios as compared with previous determinations, especially for N/O, Ne/O, and Ar/O.

Delgado-Inglada, Gloria; Morisset, Christophe; Stasi?ska, Gra?yna

2014-05-01

37

Correction of marine air temperature observations for solar radiation effects  

SciTech Connect

The effect of incoming solar radiation on merchant ships` observations of air temperature was assessed as part of the Voluntary Observing Ships` Special Observing Project for the North Atlantic (VSOP-NA). The ships` reports were compared with interpolated output from a numerical weather model. Differences between the ship values and the model values for air temperature (Delta T(sub a)) were found, in the mean, to be independent of instrument type, ship size, and, except for very badly exposed sensors, exposure. The differences were related to the relative wind speed over the ship (V) and the incoming shortwave radiation (R). The formula derived for the radiative heating error delta T was delta T = 2.7 x 10(exp -3) R - 3.2 x 10(exp -5) RV, where delta t has units of degrees Celsius, R is in watts per square meter, and V is in knots. After correcting the Delta T(sub a) values, an approximately constant bias remained with the ship reports on average 0.4 C lower than the model air temperatures. This offset probably represents a mean bias in the model estimates; however, a residual bias in the ship observations is also a possibility. There was also evidence that heat generated by the ship caused a temperature overestimate of about 0.4 C at zero relative wind, decreasing to a negligible level at a relative wind speed of 20 kt. For the North Atlantic dataset used, the correction reduced daytime marine air temperature reports by 0.63 C on average. Applying the correction to the VSOP-NA air temperature data was found to significantly change estimates of sensible and latent heat fluxes.

Kent, E.C.; Tiddy, R.J.; Taylor, P.K. [Chilworth Research Centre, Chilworth, Southampton (United Kingdom)] [Chilworth Research Centre, Chilworth, Southampton (United Kingdom)

1993-12-01

38

Eucken correction in high-temperature gases with electronic excitation  

NASA Astrophysics Data System (ADS)

In the present paper, thermal conductivity coefficient of high-temperature molecular and atomic gases with excited electronic states is studied using both the kinetic theory algorithm developed by authors earlier and the well known simple expression for the thermal conductivity coefficient proposed by Eucken and generalized by Hirschfelder. The influence of large collision diameters of excited states on the thermal conductivity is discussed. The limit of validity of the Eucken correction is evaluated on the basis of the kinetic theory calculations; an improved model suitable for air species under high-temperature conditions is proposed.

Istomin, V. A.; Kustova, E. V.; Mekhonoshina, M. A.

2014-05-01

39

Eucken correction in high-temperature gases with electronic excitation.  

PubMed

In the present paper, thermal conductivity coefficient of high-temperature molecular and atomic gases with excited electronic states is studied using both the kinetic theory algorithm developed by authors earlier and the well known simple expression for the thermal conductivity coefficient proposed by Eucken and generalized by Hirschfelder. The influence of large collision diameters of excited states on the thermal conductivity is discussed. The limit of validity of the Eucken correction is evaluated on the basis of the kinetic theory calculations; an improved model suitable for air species under high-temperature conditions is proposed. PMID:24832274

Istomin, V A; Kustova, E V; Mekhonoshina, M A

2014-05-14

40

Wall temperature measurements using a thermal imaging camera with temperature-dependent emissivity corrections  

Microsoft Academic Search

A methodology is presented whereby the relationship between temperature and emissivity for fused quartz has been used to correct the temperature values of a quartz impingement plate detected by an SC3000 thermal imaging camera. The methodology uses an iterative method using the initial temperature (obtained by assuming a constant emissivity) to find the emissivity values which are then put into

Chloe McDaid; Yang Zhang

2011-01-01

41

Quantum Mechanical Corrections to Simulated Shock Hugoniot Temperatures  

SciTech Connect

The authors present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a grueneisen equation of state and a quasi-harmonic approximation to the vibrational energies, they derive a simple, post-processing method for calculation of the quantum corrected Hugoniot temperatures. They have used our novel technique on ab initio simulations of both shock compressed water and methane. Our results indicate significantly closer agreement with all available experimental temperature data for these two systems. Our formalism and technique can be easily applied to a number of different shock compressed molecular liquids or covalent solids, and has the potential to decrease the large uncertainties inherent in many experimental Hugoniot temperature measurements of these systems.

Goldman, N; Reed, E; Fried, L E

2009-07-17

42

Quantum mechanical corrections to simulated shock Hugoniot temperatures.  

PubMed

We present a straightforward method for the inclusion of quantum nuclear vibrational effects in molecular dynamics calculations of shock Hugoniot temperatures. Using a Gruneisen equation of state and a quasiharmonic approximation to the vibrational energies, we derive a simple, postprocessing method for calculation of the quantum corrected Hugoniot temperatures. We have used our novel technique on ab initio simulations of shock compressed water and methane. Our results indicate significantly closer agreement with all available experimental temperature data for these two systems. Our formalism can be easily applied to a number of different shock compressed molecular liquids or solids, and has the potential to decrease the large uncertainties inherent in many experimental Hugoniot temperature measurements of these systems. PMID:19947671

Goldman, Nir; Reed, Evan J; Fried, Laurence E

2009-11-28

43

40 CFR 1065.670 - NOX intake-air humidity and temperature corrections.  

Code of Federal Regulations, 2010 CFR

...NOX intake-air humidity and temperature corrections... AIR POLLUTION CONTROLS ENGINE-TESTING... intake-air humidity and temperature corrections...of intake-air humidity or temperature. Use the NOX...

2010-07-01

44

40 CFR 1065.670 - NOX intake-air humidity and temperature corrections.  

Code of Federal Regulations, 2010 CFR

...NOX intake-air humidity and temperature corrections... AIR POLLUTION CONTROLS ENGINE-TESTING... intake-air humidity and temperature corrections...of intake-air humidity or temperature. Use the NOX...

2009-07-01

45

Temperature Correction of Pressure-Sensitive Paints Simplified  

NASA Technical Reports Server (NTRS)

Pressure-sensitive paint (PSP) has become a useful tool to augment conventional pressure taps in measuring the surface pressure distribution of aerodynamic components in wind tunnel testing. Although PSP offers the advantage of nonintrusive global mapping of the surface pressure, one prominent drawback to the accuracy of this technique is the inherent temperature sensitivity of PSP's luminescent intensity. Typical aerodynamic surface PSP tests rely on the coated surface to be both spatially and temporally isothermal, along with conventional instrumentation, to yield the highest accuracy pressure mappings. In some tests, however, spatial and temporal thermal gradients are generated by the nature of the test, as in a blowing jet impinging on a surface. In these cases, high accuracy and reliable data cannot be obtained unless the temperature variations on the painted surface are accounted for. A new temperature-correction technique was developed at the NASA Glenn Research Center at Lewis Field to collapse a "family" of PSP calibration curves to a single curve of intensity ratio versus pressure. This correction allows a streamlined procedure to be followed whether or not temperature information is used in the data reduction of the PSP.

Bencic, Timothy J.

2000-01-01

46

Development of a fluorescence internal quenching correction factor to correct botulinum neurotoxin type A endopeptidase kinetics using SNAPtide.  

PubMed

Botulinum neurotoxins (BoNTs), which are highly toxic proteins responsible for botulism, are produced by different strains of Clostridium botulinum. These various strains of bacteria produce seven distinct serotypes, labeled A-G. Once inside cells, the zinc-dependent proteolytic light chain (LC) degrades specific proteins involved in acetylcholine release at neuromuscular junctions causing flaccid paralysis, specifically synaptosomal-associated protein 25 (SNAP-25) for botulinum neurotoxin type A (BoNT/A). BoNT endopeptidase assays using short substrate homologues have been widely used and developed because of their ease of synthesis, detection limits, and cost. SNAPtide, a 13-amino acid fluorescence resonance energy transfer (FRET) peptide, was used in this study as a SNAP-25 homologue for the endopeptidase kinetics study of BoNT/A LC. SNAPtide uses a fluorescein isothiocyanate/4-((4-(dimethylamino)phenyl)azo) benzoic acid (FITC/DABCYL) FRET pair to produce a signal upon substrate cleavage. Signal quenching can become an issue after cleavage since quencher molecules can quench cleaved fluorophore molecules in close proximity, reducing the apparent signal. This reduction in apparent signal provides an inherent error as SNAPtide concentrations are increased. In this study, fluorescence internal quenching (FIQ) correction factors were derived using an unquenched SNAPtide peptide to quantify the signal quenching over a range of SNAPtide concentrations and temperatures. The BoNT/A LC endopeptidase kinetics at the optimally active temperature (37 C) using SNAPtide were studied and used to demonstrate the FIQ correction factors in this study. The FIQ correction factors developed provide a convenient method to allow for improved accuracy in determining and comparing BoNT/A LC activity and kinetics using SNAPtide over a broad range of concentrations and temperatures. PMID:23181535

Feltrup, Thomas M; Singh, Bal Ram

2012-12-18

47

Semiclassical zero-temperature corrections to Schwarzschild spacetime and holography  

SciTech Connect

Motivated by the quest for black holes in anti-de Sitter braneworlds, and, in particular, by the holographic conjecture relating 5D classical bulk solutions with 4D quantum corrected ones, we numerically solve the semiclassical Einstein equations (backreaction equations) with matter fields in the (zero-temperature) Boulware vacuum state. In the absence of an exact analytical expression for in four dimensions we work within the s-wave approximation. Our results show that the quantum corrected solution is very similar to Schwarzschild spacetime until very close to the horizon, but then a bouncing surface for the radial function appears which prevents the formation of an event horizon. We also analyze the behavior of the geometry beyond the bounce, where a curvature singularity arises. In the dual theory, this indicates that the corresponding 5D static classical braneworld solution is not a black hole but rather a naked singularity.

Fabbri, A.; Farese, S.; Navarro-Salas, J.; Sanchis-Alepuz, H. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia (Spain); Olmo, G.J. [Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin, 53201 (United States)

2006-05-15

48

Corrections for Convective Heat Flux Gauges Subjected to a Surface Temperature Discontinuity  

NASA Technical Reports Server (NTRS)

A two-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been carried out in an effort to determine the convective heat transfer corrections for circular heat flux gauges subjected to a surface temperature discontinuity. Solutions were obtained at a Reynolds number Of 1 x 10(exp 6) and a Mach number of 4. The CFD results are compared with the existing correlations for the correction factors. In general, the CFD corrections exceed those provided by the correlations. The discrepancy increases with increasing upstream surface temperature, thus indicating the role of property variations, which are not accounted for in the correlations. A quasi-two-dimensional analysis is also performed to treat the cylindrical geometry of the heat flux gauges by area-averaging the computed two-dimensional results from CFD.

Kandula, M.; Reinarts, T.; Voska, N. (Technical Monitor)

2002-01-01

49

Chiral restoration at finite temperature with meson loop corrections  

SciTech Connect

We investigate the pattern of chiral-symmetry restoration of QCD for N{sub c}=3 and N{sub f}=2 at finite temperature (T) beyond the chiral limit. To this end, we employ the instanton-vacuum configuration for the flavor SU(2) sector and the Harrington-Shepard caloron for modifying relevant instanton parameters as functions of T. The meson loop corrections (MLC), which correspond to 1/N{sub c} corrections, are also taken into account to reproduce appropriate m{sub q} dependences of chiral order parameters. We compute the chiral condensate as a function of T and/or m{sub q}. We observe that MLC play an important role to have a correct universality-class behavior of chiral-restoration patterns in this framework, depending on m{sub q}: Second-order phase transition in the chiral limit m{sub q}=0 and cross-over for m{sub q{ne}}0. Without MLC, all the restoration patterns are crossover, due to simple saddle-point approximations. It turns out that T{sub c}{sup {chi}=}159 MeV in the chiral limit and T{sub c}{sup {chi}=}(177,186,196) MeV for m{sub q}=(5,10,15) MeV, using the phenomenological choices for the instanton parameters at T=0.

Nam, Seung-il [Department of Physics, Chung-Yuan Christian University, Chung-Li 32023, Taiwan (China); Research Institute of Basic Sciences, Korea Aerospace University, Koyang, 412-791 (Korea, Republic of); Kao, Chung-Wen [Department of Physics, Chung-Yuan Christian University, Chung-Li 32023, Taiwan (China)

2010-11-01

50

Broadband emission factors: temperature variation for nongray samples  

NASA Astrophysics Data System (ADS)

The general problem of extracting the correct emission factor from broadband radiometric measurements on non-gray samples is treated with emphasis on polycrystalline beryllium oxide and BeO with a coating of silicon. These samples exhibit a strong spectral variation in their emittance functions where the Planck function has large weight. Under these circumstances the band-averaged emission factor will be temperature dependent, even if the spectral emittance is temperature independent. The consequences of this for the conventional expression which includes a correction for radiance from the surroundings reflected by the sample are investigated. It is concluded that the observation of a temperature variation in this emission factor not only violates an assumption of the derivation, it is also a criterion indicating that the numerical value is incorrect Two algorithms, based on linearization and iteration of the temperature variation are introduced and applied to an emittance step model and the experimental radiometer values for the reststrahlen band materials. It is found that the emission factors obtained after this correction procedure are in significantly better agreement with values obtained from weighted integration of spectral emittance over the spectral window of the radiometer. The room-temperature value of the upper TIR emission factor is 0.40 and 0.22 for BeO and the Si-BeO double layer respectively. A sand-blasted aluminum sample had almost perfectly gray emittance and the emission factor is 0.39 and temperature independent.

Staaf, Oerjan; Ribbing, Carl G.; Andersson, Stefan K.

1996-03-01

51

Harmonic measurements and analysis for power factor correction  

SciTech Connect

Maximizing electric power transfer directly effects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These harmonic currents cause system voltage distortions, power loss in the system, and can interact with power factor correction capacitor banks leading to equipment failures. This paper presents the analytical technique used to correct power factor in a modern steel manufacturing facility. The study included field measurements, harmonic analysis, and filter design work to reduce the amount of harmonic distortion in the plant. The modeling of arc furnaces and rolling mills for a harmonic analysis study is also discussed. The solution recommended in this paper to increase power factor and reduce harmonics can be applied to other steel manufacturing facilities to improve power quality and therefore plant productivity.

Witte, J.F.; Bishop, M.T. (Cooper Power Systems, Franksville, WI (United States)); Andrews, D. (North Star Steel Texas, Inc., Beaumont, TX (United States))

1993-07-01

52

[The pharmacological correction of factors limiting human work capacity].  

PubMed

The problem of pharmacological correction of working capacity and rehabilitation after exhausting physical exertion is discussed from the standpoint of current advances and detection of factors limiting man's working capacity. The removal of factors interfering with the development of optimal possibilities of man through the effect of medicinal drugs is considered. The article discusses the energy sources providing for the performance of physical work differing in power and duration in accordance with the specificity of a type of sports as a most convenient model for studying adaptation to physical exertion. Factors limiting the working capacity of athletes are classified on the basis of current advances in biochemistry and physiology. All pharmacological agents influencing human working capacity are classified according to the potency zones determining the supply of energy. Pharmacological monitoring of man's capacity for work is in fact disclosure of factors limiting it and their pharmacological correction. This allows planning of the means for excluding the use of dope drugs in sports medicine and scientifically substantiated use of drugs in heavy branches of industry, for promoting climato-zone adaptation, and in extreme conditions. It is shown that the use of strongly active drugs is not necessary because a large reserve is available of drugs of plant and animal origin possessing much lesser side effects. PMID:9575403

Se?fulla, R D

1998-01-01

53

Monte Carlo simulation of correction factors for IAEA TLD holders.  

PubMed

The IAEA standard thermoluminescent dosimeter (TLD) holder has been developed for the IAEA/WHO TLD postal dose program for audits of high-energy photon beams, and it is also employed by the ESTRO-QUALity assurance network (EQUAL) and several national TLD audit networks. Factors correcting for the influence of the holder on the TL signal under reference conditions have been calculated in the present work from Monte Carlo simulations with the PENELOPE code for (60)Co gamma-rays and 4, 6, 10, 15, 18 and 25 MV photon beams. The simulation results are around 0.2% smaller than measured factors reported in the literature, but well within the combined standard uncertainties. The present study supports the use of the experimentally obtained holder correction factors in the determination of the absorbed dose to water from the TL readings; the factors calculated by means of Monte Carlo simulations may be adopted for the cases where there are no measured data. PMID:20197601

Hultqvist, Martha; Fernndez-Varea, Jos M; Izewska, Joanna

2010-03-21

54

Gradient corrections to finite-temperature exchange-correlation functionals  

NASA Astrophysics Data System (ADS)

In principle, the only approximation in Kohn-Sham DFT is for the exchange-correlation (XC) energy. As such, about 40 years of development for the zero-temperature XC density functional has resulted in a ladder of functionals from simple LDA (based on essentially exact QMC results) to orbital-dependent functionals including virtuals. The non-zero temperature situation is different. To date, a handful of T 0 K XC functionals have been introduced based on approximate electron gas calculations or interpolations. Except for a finite-T gradient expansion of X, all are local density approximations. Here we present calculations for the XC energy of the electron gas in the dielectric formalism, specifically with approximate local field corrections (LFC). Analysis of the LCF is used to evaluate the first term of the gradient expansion of the XC energy in the slowly varying limit. The resulting gradient expansion finite temperature XC functional will be presented and possible generalized gradient approximations will be considered.

Sjostrom, Travis; Dufty, James

2013-03-01

55

Simple correction factor for laser speckle imaging of flow dynamics  

PubMed Central

One of the major constraints facing laser speckle imaging for blood-flow measurement is reliable measurement of the correlation time (?C) of the back-scattered light and, hence, the bloods speed in blood vessels. In this Letter, we present a new model expression for integrated speckle contrast, which accounts not only for temporal integration but spatial integration, too, due to the finite size of the pixel of the CCD camera; as a result, we find that a correction factor should be introduced to the measured speckle contrast to properly determine ?C; otherwise, the measured bloods speed is overestimated. Experimental results support our theoretical model.

Ramirez-San-Juan, J. C.; Ramos-Garcia, R.; Martinez-Niconoff, G.; Choi, B.

2014-01-01

56

Compilation of Temperature Factors of Cubic Elements,  

National Technical Information Service (NTIS)

A compilation is presented of the temperature factors of twenty cubic elements. This represents the first stage of a Temperature Factor project sponsored by the Neutron Diffraction Commission of the I.U.Cr. (Acta Cryst (1985) B41 374).

N. M. Butt B. T. M. Willis G. Heger J. Bashir

1986-01-01

57

Diurnal drift correction in the NESDIS/STAR MSU/AMSU atmospheric temperature climate data record  

NASA Astrophysics Data System (ADS)

NESDIS/Center for Satellite Applications and Research (STAR) has been reprocessing and recalibrating observations from the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) to generate atmospheric temperature climate data record (CDR). To obtain reliable atmospheric temperature trends from the dataset, diurnal drift errors due to orbital drift must be removed from the time series. This adjustment is especially important for the MSU/AMSU mid-tropospheric temperature product over land where diurnal-drift effect is large. In this study, we applied the diurnal anomalies developed by the Remote Sensing Systems (RSS) to the STAR MSU/AMSU atmospheric temperatures CDR and examined how the correction affects the trend and intersatellite biases over land. A scaling factor was introduced to multiply the RSS diurnal anomalies to account for uncertainties in the dataset. The results show that the diurnal drift has negligible effect on the mid-tropospheric temperature trends over oceans, which is consistent with previous investigations. However, the trend over land is very sensitive to the magnitude of the scaling factor. The final scaling factor was determined by minimizing intersatellite temperature differences over land. The trend values corresponding to such a scaling factor for the 28-year (1979-2006) merged MSU T2 time series are 0.193 K/Decade over the global land and 0.180 K/Decade over the global ocean. The global mean T2 trend is 0.183 K/decade.

Zou, Cheng-Zhi; Wang, Wenhui

2009-08-01

58

Correction for thermal lag in dynamic temperature measurements using resistance thermometers.  

PubMed

Periodical changes of temperature in the autoclave for the purpose of automatic control are measured with the aid of an encased resistance thermometer. To minimize dynamic errors of this thermometer, two different correcting algorithms have been employed: a known single time-constant one and an algorithm proposed by the authors-two time-constant one. The verification and comparison of the two algorithms was done using a physical model of the autoclave and a real thermometer. Additionally, three methods for the determination of time constants of the second order model were compared and factors influencing the algorithms accuracy, including time constants and sampling time, were analysed. The presented methods make possible to increase both the bandwidth of dynamical temperature measurements and its precision with relatively limited increase in computational complexity of the correction algorithm. PMID:23902092

Tomczuk, Krzysztof; Werszko, Radoslaw

2013-07-01

59

Wall temperature measurements using a thermal imaging camera with temperature-dependent emissivity corrections  

NASA Astrophysics Data System (ADS)

A methodology is presented whereby the relationship between temperature and emissivity for fused quartz has been used to correct the temperature values of a quartz impingement plate detected by an SC3000 thermal imaging camera. The methodology uses an iterative method using the initial temperature (obtained by assuming a constant emissivity) to find the emissivity values which are then put into the thermal imaging software and used to find the subsequent temperatures, which are used to find the emissivities, and so on until converged. This method is used for a quartz impingement plate that has been heated under various flame conditions, and the results are compared. Radiation losses from the plate are also calculated, and it is shown that even a slight change in temperature greatly affects the radiation loss. It is a general methodology that can be used for any wall material whose emissivity is a function of temperature.

McDaid, Chloe; Zhang, Yang

2011-12-01

60

Use of correction factors in mobility shift affinity capillary electrophoresis for weak analyte-ligand interactions.  

PubMed

The practical and theoretical problems associated with interpretation of binding isotherms obtained by the investigation of weak analyte-ligand interactions using mobility shift affinity CE were investigated with special emphasis on various correction methods to compensate for media effects due to high additive concentrations. The interaction between 2-hydroxypropyl-alpha-CD and two bile salts (glycocholate and glycodeoxycholate) was studied applying correction factors based on viscosity, CE based conductance and separately measured conductivities. Accurate measurement of the stability constants proved to be difficult; several points of general nature relating to the investigation of the weak analyte-ligand interactions were identified. These included undesired dilution of the BGE due to the high amounts of additive, avoidance of temperature effects by maintaining a constant power during the separations and limited validity of Walden's rule. The relative sizes of the buffer constituents, the nonelectrolyte ligand additive, and the analytes as well as noninteracting marker substances should be considered in order to minimize errors in the correction factors when significant deviation from Walden's rule is observed. Under such conditions, the mobilities should preferably be corrected by the use of a noninteracting marker; and the most generally applicable corrections may be based on conductance measurements. PMID:19472279

stergaard, Jesper; Jensen, Henrik; Holm, Ren

2009-05-01

61

Production of element correction factors for thermoluminescent dosimeters  

SciTech Connect

Approximately 80 processors of personal dosimetry in the United States use thermoluminescent dosimeters (TLDs). Recent demands that dosimetry processors be able to measure radiation doses to within +/- 50% of the correct value have focused attention on the reproducibility of the TL elements within each TLD. The phosphors for these TLDs are manufactured by three companies. A dosimetry processor faces three options concerning the quality of the TL elements purchased; trust the supplier's quality control program, screen new TL elements and discard those that are extremely bad, or use element correction factors (ECFs). The first option results in dosimetry processors failing the +/- 50% accuracy requirement due to excessive variability among the TL elements. The second option still permits large precision errors that come close to the +/- 50% accuracy requirement. This paper advocates the third option and presents a 10-step procedure to produce ECFs. The procedure ensures that the ECFs represent only variations among the TL elements and not variations caused by stability problems with the TLD reader. Following is an example of ECF production for 3000 TLDs.

Plato, P.; Miklos, J.

1985-11-01

62

Quality correction factors of composite IMRT beam deliveries: Theoretical considerations  

SciTech Connect

Purpose: In the scope of intensity modulated radiation therapy (IMRT) dosimetry using ionization chambers, quality correction factors of plan-class-specific reference (PCSR) fields are theoretically investigated. The symmetry of the problem is studied to provide recommendable criteria for composite beam deliveries where correction factors are minimal and also to establish a theoretical limit for PCSR delivery k{sub Q} factors. Methods: The concept of virtual symmetric collapsed (VSC) beam, being associated to a given modulated composite delivery, is defined in the scope of this investigation. Under symmetrical measurement conditions, any composite delivery has the property of having a k{sub Q} factor identical to its associated VSC beam. Using this concept of VSC, a fundamental property of IMRT k{sub Q} factors is demonstrated in the form of a theorem. The sensitivity to the conditions required by the theorem is thoroughly examined. Results: The theorem states that if a composite modulated beam delivery produces a uniform dose distribution in a volume V{sub cyl} which is symmetric with the cylindrical delivery and all beams fulfills two conditions in V{sub cyl}: (1) the dose modulation function is unchanged along the beam axis, and (2) the dose gradient in the beam direction is constant for a given lateral position; then its associated VSC beam produces no lateral dose gradient in V{sub cyl}, no matter what beam modulation or gantry angles are being used. The examination of the conditions required by the theorem lead to the following results. The effect of the depth-dose gradient not being perfectly constant with depth on the VSC beam lateral dose gradient is found negligible. The effect of the dose modulation function being degraded with depth on the VSC beam lateral dose gradient is found to be only related to scatter and beam hardening, as the theorem holds also for diverging beams. Conclusions: The use of the symmetry of the problem in the present paper leads to a valuable theorem showing that k{sub Q} factors of composite IMRT beam deliveries are close to unity under specific conditions. The theoretical limit k{sub Q{sub p{sub c{sub s{sub r,Q{sub m{sub s{sub r}{sup f{sub p}{sub c}{sub s}{sub r},f{sub m}{sub s}{sub r}}}}}}}}}=1 is determined based on the property of PCSR deliveries to provide a uniform dose in the target volume. The present approach explains recent experimental observations and proposes ideal conditions for IMRT reference dosimetry. The result of this study could potentially serve as a theoretical basis for reference dosimetry of composite IMRT beam deliveries or for routine IMRT quality assurance.

Bouchard, Hugo [Departement de radio-oncologie, Centre hospitalier de l'Universite de Montreal (CHUM), 1560 Sherbrooke est, Montreal, Quebec H2L 4M1 (Canada)

2012-11-15

63

Bonferroni-based correction factor for multiple, correlated endpoints.  

PubMed

Multiple testing and its impact on the type I and type II error rates are frequently discussed in the statistical and biomedical literature. The Bonferroni adjustment is one of the most widely used approaches, yet it suffers from poor statistical performance when there are correlated test statistics. For example, it is criticized to be too conservative. Nonetheless, part of the strong appeal of the Bonferroni approach is the straightforward implementation and relatively intuitive explanation. In this manuscript, a novel adaptation to the traditional Bonferroni approach that accounts for correlated data is proposed. A simple correction factor based on intraclass correlation is applied to the standard Bonferroni method to overcome the shortcomings of the standard Bonferroni adjustment yet maintains its advantages. The method is motivated by an early phase clinical trial examining the effect of a study medication on marijuana craving, which is commonly quantified into four correlated constructs. A detailed simulation study demonstrated that the proposed approach is statistically sound and appropriate for a wide range of common settings. PMID:22588983

Shi, Qian; Pavey, Emily S; Carter, Rickey E

2012-01-01

64

Stress Intensity Factor Plasticity Correction for Flaws in Stress Concentration Regions.  

National Technical Information Service (NTIS)

Plasticity corrections to elastically computed stress intensity factors are often included in brittle fracture evaluation procedures. These corrections are based on the existence of a plastic zone in the vicinity of the crack tip. Such a plastic zone corr...

E. Friedman W. K. Wilson

2000-01-01

65

Evaluation of enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index  

Microsoft Academic Search

The purpose of this paper is made to clarify that the relationship between the human physiological and psychological responses and the enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index upon the human body. Environmental factors and human physiological and psychological responses were measured. It was made clear that the variables by which summer outdoor environmental

Yoshihito Kurazumi; Tadahiro Tsuchikawa; Naoki Matsubara; Emi Kondo; Tetsumi Horikoshi

2011-01-01

66

75 FR 5536 - Pipeline Safety: Control Room Management/Human Factors, Correction  

Federal Register 2010, 2011, 2012, 2013

...Safety: Control Room Management/Human Factors, Correction AGENCY: Pipeline...Safety Regulations to address human factors and other aspects of control room...Safety: Control Room Management/Human Factors.'' This final rule...

2010-02-03

67

Correction  

NASA Astrophysics Data System (ADS)

We regret that figure 1 in The freeze-drying of wet and waterlogged materials from archaeological excavations (Watson J 2004 Phys. Educ. 39 171-6) is incorrect. The correct figure is shown here. The graph is adapted from one available at wine1.sb.fsu.edu/chm1045/notes/Forces/Phase/Forces06.htm. The error occurred in production and was not the fault of the author. Corrected figure

2004-07-01

68

New Correction Technique for Strain-Gage Measurements Acquired in Transient-Temperature Environments.  

National Technical Information Service (NTIS)

Significant strain-gage errors may exist in measurements acquired in transient-temperature environments if conventional correction methods are applied. As heating or cooling rates increase, temperature gradients between the strain-gage sensor and substrat...

W. L. Richards

1996-01-01

69

Apparatus and method for temperature correction and expanded count rate of inorganic scintillation detectors  

DOEpatents

The present invention includes an apparatus and corresponding method for temperature correction and count rate expansion of inorganic scintillation detectors. A temperature sensor is attached to an inorganic scintillation detector. The inorganic scintillation detector, due to interaction with incident radiation, creates light pulse signals. A photoreceiver processes the light pulse signals to current signals. Temperature correction circuitry that uses a fast light component signal, a slow light component signal, and the temperature signal from the temperature sensor to corrected an inorganic scintillation detector signal output and expanded the count rate.

Ianakiev, Kiril D. (Los Alamos, NM); Hsue, Sin Tao (Santa Fe, NM); Browne, Michael C. (Los Alamos, NM); Audia, Jeffrey M. (Abiquiu, NM)

2006-07-25

70

Note: Vignetting calibration and temperature correction for casting billets  

NASA Astrophysics Data System (ADS)

A method for calibration of vignetting coefficient is proposed in this paper to solve the distortion of temperature measurement using a CCD-based pyrometer. On this basis, a hybrid temperature measurement system, which comprises of an array CCD camera with high resolution and a single spot colorimetric thermometer, is introduced to eliminate the influences of surface striped iron oxide scale, dust, and emissivity on temperature measurement for casting billets. Currently, the system has been successfully applied and verified in some continuous casting production lines. The vignetting estimation error of 0.052 and the maximum temperature measurement fluctuation of 5 C were achieved in these measurements.

Xie, Zhi; Zhang, Yuzhong; Hu, Zhenwei; Bai, Haicheng

2013-09-01

71

SCIENTIFIC NOTE: A method of taking into account the inhomogeneity backscatter contribution to the Batho correction factor (radiotherapy dosimetry)  

Microsoft Academic Search

Reports an algorithm for an inhomogeneity backscatter correction factor which can separately take into account the change in backscattering from materials beyond the point of interest. The total correction factor is the product of an ordinary inhomogeneity correction factor, such as that based on the Batho power law or additive scatter-air ratio method, and an inhomogeneity backscatter correction factor.

A. Iwasaki

1986-01-01

72

Correction of marine air temperature observations for solar radiation effects  

Microsoft Academic Search

The effect of incoming solar radiation on merchant ships` observations of air temperature was assessed as part of the Voluntary Observing Ships` Special Observing Project for the North Atlantic (VSOP-NA). The ships` reports were compared with interpolated output from a numerical weather model. Differences between the ship values and the model values for air temperature (Delta T(sub a)) were found,

E. C. Kent; R. J. Tiddy; P. K. Taylor

1993-01-01

73

A New Correction Technique for Strain-Gage Measurements Acquired in Transient-Temperature Environments  

NASA Technical Reports Server (NTRS)

Significant strain-gage errors may exist in measurements acquired in transient-temperature environments if conventional correction methods are applied. As heating or cooling rates increase, temperature gradients between the strain-gage sensor and substrate surface increase proportionally. These temperature gradients introduce strain-measurement errors that are currently neglected in both conventional strain-correction theory and practice. Therefore, the conventional correction theory has been modified to account for these errors. A new experimental method has been developed to correct strain-gage measurements acquired in environments experiencing significant temperature transients. The new correction technique has been demonstrated through a series of tests in which strain measurements were acquired for temperature-rise rates ranging from 1 to greater than 100 degrees F/sec. Strain-gage data from these tests have been corrected with both the new and conventional methods and then compared with an analysis. Results show that, for temperature-rise rates greater than 10 degrees F/sec, the strain measurements corrected with the conventional technique produced strain errors that deviated from analysis by as much as 45 percent, whereas results corrected with the new technique were in good agreement with analytical results.

Richards, W. Lance

1996-01-01

74

A maximum likelihood approach for estimating the QT correction factor using mixed effects model.  

PubMed

Assessment of QT interval prolongation is often used for assessing the cardiac safety of a new drug. However, the correction of the QT interval for varying heart rates has potential bias due to various different correction factors. This article proposes a maximum likelihood (ML) approach for calculating the appropriate individual correction factor using the data. The data come from a study with 24 subjects participating in a 10 day multiple dose (NEW RX) placebo-controlled cross-over trial with repeat ECGs obtained at baseline and at day 10. ML techniques were used to fit a random-effects model to observed QT and HR values for estimating the pooled and individual correction factors. QT(c) values using four correction factors (Bazett, Friderecia, pooled and individual) were investigated. The relative performance of the various correction factors are given in terms of variability and graphical techniques. The pooled correction factor was estimated to be 0.292 and the individual correction factors ranged from 0.19 to 0.41. The assessment of the treatment effect on QT(c) yielded inconsistent results. Bazett's factor indicated prolongation (6.55+/-1.20), Friderecia's factor indicated no change, while the pooled (-2.92+/-0.94) and individual (-2.82+/-1.00) factors showed a significant decrease. Graphical examination of individual QT(c) data showed a significant advantage in the use of individual correction factors versus Bazett's factor both in terms of sensitivity as well as reduction in bias. Use of individual correction factors is advocated for the assessment of possible drug-induced QT(c) prolongation. PMID:12754723

Shah, Amrik; Hajian, Gerald

2003-06-15

75

Spatial correction factors for YALINA Booster facility loaded with medium and low enriched fuels  

SciTech Connect

The Bell and Glasstone spatial correction factor is used in analyses of subcritical assemblies to correct the experimental reactivity as function of the detector position. Besides the detector position, several other parameters affect the correction factor: the energy weighting function of the detector, the detector size, the energy-angle distribution of source neutrons, and the reactivity of the subcritical assembly. This work focuses on the dependency of the correction factor on the detector material and it investigates the YALINA Booster subcritical assembly loaded with medium (36%) and low (10%) enriched fuels. (authors)

Talamo, A.; Gohar, Y. [Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL 60439 (United States); Bournos, V.; Fokov, Y.; Kiyavitskaya, H.; Routkovskaya, C. [Joint Inst. for Power and Nuclear Research-Sosny, 99 Academician A.K.Krasin Str, Minsk 220109 (Belarus)

2012-07-01

76

Power Factor Correction of Single-Phase Induction Motor Using Magnetic Energy Recovery Switch  

NASA Astrophysics Data System (ADS)

Magnetic energy recovery switch (MERS) has a function of automatic power factor correction of series connected load. The MERS is applied for a single-phase induction motor to improve the power factor. Two control methods of the MERS for power factor correction are described in this paper. Experiments were carried out and confirmed that the input power factor of a single-phase induction motor is improved.

Takaku, Taku; Narushima, Jun; Isobe, Takanori; Kitahara, Tadayuki; Shimada, Ryuichi

77

Recombinant factor VIIa corrects prothrombin time in cirrhotic patients: A preliminary study  

Microsoft Academic Search

BACKGROUND & AIMS: Cirrhotic patients with a prolonged prothrombin time (PT) are known to have low levels of factor VII. Because the current modalities to correct this problem are not ideal, recombinant factor VIIa (rFVIIa) may be useful in correcting the prolonged PT observed in the coagulopathy of cirrhosis. The aim of this study was to evaluate the effectiveness of

DE Bernstein; L Jeffers; E Erhardtsen; KR Reddy; S Glazer; P Squiban; R Bech; U Hedner; ER Schiff

1997-01-01

78

Two dimensional bias correction of temperature and precipitation copulas in climate models  

NASA Astrophysics Data System (ADS)

In common climate model bias-correction procedures, temperature and precipitation are corrected separately, thereby degrading the dynamical link represented within the model. We propose a methodology that advances the state-of-the-art by correcting not just the 1D intensity distributions separately but the full two-dimensional statistical distribution. To assess the effectiveness of the proposed method, it is applied to the REMO regional climate model output using point measurements of hourly temperature and precipitation from 6 weather stations over Germany as observations. A standard cross-validation is performed by dividing the data into two nonoverlapping 15 year periods. Results show that the methodology effectively improves the temperature-precipitation copula in the validation period, unlike separate 1D temperature and precipitation corrections which, by construction, leave the copula unchanged. An unexpected result is that a relatively small number (<5) of temperature bins are required to achieve significant improvements in the copula. Results are similar for all stations.

Piani, C.; Haerter, J. O.

2012-10-01

79

Correction  

NASA Astrophysics Data System (ADS)

Alleged mosasaur bite marks on Late Cretaceous ammonites are limpet (patellogastropod) home scars Geology, v. 26, p. 947 950 (October 1998) This article had the following printing errors: p. 947, Abstract, line 11, sepia should be septa p. 947, 1st paragraph under Introduction, line 2, creep should be deep p. 948, column 1, 2nd paragraph, line 7, creep should be deep p. 949, column 1, 1st paragraph, line 1, creep should be deep p. 949, column 1, 1st paragraph, line 5, 19774 should be 1977) p. 949, column 1, 4th paragraph, line 7, in particular should be In particular CORRECTION Mammalian community response to the latest Paleocene thermal maximum: An isotaphonomic study in the northern Bighorn Basin, Wyoming Geology, v. 26, p. 1011 1014 (November 1998) An error appeared in the References Cited. The correct reference appears below: Fricke, H. C., Clyde, W. C., O'Neil, J. R., and Gingerich, P. D., 1998, Evidence for rapid climate change in North America during the latest Paleocene thermal maximum: Oxygen isotope compositions of biogenic phosphate from the Bighorn Basin (Wyoming): Earth and Planetary Science Letters, v. 160, p. 193 208.

1998-12-01

80

Urban-Effect Correction to Improve Accuracy of Spatially Interpolated Temperature Estimates in Korea  

Microsoft Academic Search

Gridded temperature data are frequently used to run ecological models at regional scales and are routinely generated by spatially interpolating point observations at synoptic weather stations. If synoptic stations are located in urbanized areas, observed temperature and the interpolated data could be contaminated by the urban heat island effect. Without an appropriate correction, temperature estimates over rural areas or forests

Jaeyeon Choi; Uran Chung; Jin I. Yun

2003-01-01

81

Parameterized nonuniformity corrections (NUC) for non-temperature stabilized InGaAs SWIR sensing  

NASA Astrophysics Data System (ADS)

Military applications for conventional InGaAs SWIR sensing have been limited by the requirement of thermoelectric cooler (TEC) temperature stabilization for nonuniformity correction (NUC). TEC operation restricts the operating temperature range and size, weight, and power (SWAP) of these systems. For battery-powered man portable and micro UAV applications elimination of the TEC is critical. This paper discusses the advantages of our non-TEC temperature parameterized NUC corrections algorithms versus TEC stabilized architectures. The corrections algorithms enable performance-tuned polynomial order correction of both pixel uniformity and temperature parameterization for each SWIR sensor. These advances enable SWIR InGaAs sensing to meet the SWAP requirements of next generation military applications.

Battaglia, Jesse; Burzi, Vincent; Moyer, Bruce; Sudol, Thomas; Passe, Joseph

2010-04-01

82

Temperature dependence of the local-field correction function (in Ukrainian)  

Microsoft Academic Search

Dynamic local--field correction function for models of Fermi--systems model has been investigated at low temperature in the region of the strong degeneration. It has been shown that temperature dependence of the local--field correction function expressed by a long--wave asymptote of the interaction potential and coupling parameter. This function for the electron liquid model has been calculated in the weak and

M. V. Vavrukh; V. N. Paslavs'kiy; N. L. Tyshko

2000-01-01

83

Prediction of tunnel lining loads using correction factors  

Microsoft Academic Search

A design method for the prediction of lining loads should include the decrease of lining loads due to the stress release before lining installation and the increase of lining loads due to development of ground yielding. Schwartz and Einstein included both factors in their original closed form solutions in the form of a support delay factor ?d and a yield

H. J. Kim; Z. Eisenstein

2006-01-01

84

Correction factors for a cylindrical ionization chamber used in medium-energy X-ray beams  

Microsoft Academic Search

Correction factors are derived for a cylindrical NE2571 ionization chamber, for absorbed dose determinations in medium-energy X-rays. These new correction factors are proposed as weighted mean values of the factors derived from two methods. The first method is based on a comparative study of dosimetry of medium-energy X-rays with the cylindrical ionization chamber and a water calorimeter. The calorimetric results

J. Seuntjens; H. Thierens; U. Schneider

1993-01-01

85

Temperature Dependence of Factors Controlling Isoprene Emissions  

NASA Technical Reports Server (NTRS)

We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

2009-01-01

86

Experimental verification of Theodorsen's theoretical jet-boundary correction factors  

NASA Technical Reports Server (NTRS)

Prandtl's suggested use of a doubly infinite arrangement of airfoil images in the theoretical determination of wind-tunnel jet-boundary corrections was first adapted by Glauert to the case of closed rectangular jets. More recently, Theodorsen, using the same image arrangement but a different analytical treatment, has extended this work to include not only closed but also partly closed and open tunnels. This report presents the results of wind-tunnel tests conducted at the Georgia School of Technology for the purpose of verifying the five cases analyzed by Theodorsen. The tests were conducted in a square tunnel and the results constitute a satisfactory verification of his general method of analysis. During the preparation of the data two minor errors were discovered in the theory and these have been rectified.

Schliestett, George Van

1934-01-01

87

Factors Influencing the Design, Establishment, Administration, and Governance of Correctional Education for Females  

ERIC Educational Resources Information Center

This article summarizes the results of a study conducted to investigate factors influencing the organizational design, establishment, administration, and governance of correctional education for females. The research involved interviews with correctional and community college administrators and practitioners representing North Carolina female

Ellis, Johnica; McFadden, Cheryl; Colaric, Susan

2008-01-01

88

Power Factor Correction Using Magnetic Energy Recovery Current Switches  

Microsoft Academic Search

In this paper, we propose a Magnetic Energy Recovery Switch (MERS). The switch consists of four MOSFET elements and one capacitor. A power factor improvement is automatically possible regardless of the impedance and power frequency of the load by synchronized switching of MERS with a power supply. MERS itself generates voltage and compensates for the inductance voltage unlike a conventional

Taku Takaku; Takanori Isobe; Jun Narushima; Hiroaki Tsutsui; Ryuichi Shimada

2005-01-01

89

New soft tissue correction factors for stature estimation: results from magnetic resonance imaging.  

PubMed

In stature reconstruction using Fully's method, it is essential that a soft tissue correction factor be added to skeletal height in order to obtain an estimate of living stature. While some anthropologists consider Fully's method to be the most reliable for stature estimation, others consider it to be inadequate as it seems to be underestimating living stature, possibly due to an error in the magnitude of Fully's soft tissue factors. A recent study by Raxter and co-workers revised Fully's technique and also presented a new "universally applicable" soft tissue correction factor. The present study examines the reliability of soft tissue correction factors of Fully and Raxter et al. on a living sample of indigenous South African males. The current study is based on data collected from 28 indigenous South African (ISA) male volunteers. Standing height of each subject was measured using a stadiometer. Fully's method was used in the calculation of total skeletal height from a full body MRI scan of each subject. Subsequent analyses of the acquired data revealed that the previously derived soft tissue correction factors are not applicable to the studied sample, and why they are not applicable. The correction factors of Fully and Raxter et al. both significantly underestimate living stature in a living sample of indigenous South African males. Consequently, a new correction factor was calculated based on the prediction of living stature from TSH using regression analysis. PMID:21937173

Bidmos, Mubarak Ariyo; Manger, Paul Robert

2012-01-10

90

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

NASA Astrophysics Data System (ADS)

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.

olc, Jaroslav; Sochor, Vladimr

2014-06-01

91

Two dimensional bias correction of temperature and precipitation copulas in climate models  

NASA Astrophysics Data System (ADS)

In most climate model bias-correction procedures, temperature and precipitation are corrected independently, thereby degrading the dynamical link represented within the model. We propose a methodology that advances the state-of-the-art by correcting not just the independent intensity distributions but the full two-dimensional statistical distribution of temperature and precipitation as described by the copula. To illustrate the methodology and its potential to affect copulas, it was applied to a synthetic temperature and precipitation (T&P) dataset. Figure 1a shows two histograms derived from synthetic 2D T&P datasets. The dashed color-filled contours represent the simulated T&P data histogram while the solid contours represent the observed T&P data. The distribution shown in fig. 1e is the copula extracted from the synthetic observed T&P data set used to derive the non-colored 2D histogram shown in fig. 1a. The copula extracted from the simulated data is flat. In fig 1b (1c) the simulated 2D histogram has been bias corrected using linear (high order) 1D bias corrections separately for temperature and precipitation. Inspection of fig. 1b and 1c will reveal that the simple independent bias corrections of temperature and precipitation improve the 2D histogram greatly without affecting the copula at all. In fact the copulas derived from the 2D colored histograms in fig 1b and 1c are still flat! Finally, in fig. 1d, the full 2D bias correction is applied. Figure 1f shows the copula of the corrected data from fig. 1d. Now that we have applied the full 2D bias correction developed in this study, we obtain some structure in the derived copula. To assess the effectiveness of the proposed method, it is applied to the a regional climate model output and weather station data over Germany. A standard cross-validation is performed by dividing the data into two non overlapping 10 year periods. Results show that the methodology effectively improves the temperature-precipitation copula in the validation period, unlike independent temperature and precipitation corrections which, by construction, leave the copula unchanged. Figure 1. Synthetic histograms of simulated (dashed color filled contours) and observed (solid contours) of temperature and precipitation.

Piani, C.; Haerter, J. O.

2012-12-01

92

Power-Factor Correction of Resistance Welding Machines Series Capacitors  

Microsoft Academic Search

Resistance-welding machines usually are characterized by a large intermittent kilovolt-ampere demand at low power factor which is sometimes difficult to handle on the available power circuits due to regulation problems. Frequently the situation is so acute that power companies are unable to serve large resistance-welding machines, because the cost of reinforcing the system to render the desired service is disproportionate

L. G. Levoy

1940-01-01

93

Area detector corrections for high quality synchrotron X-ray structure factor measurements  

SciTech Connect

Correction procedures for obtaining accurate X-ray structure factors from large area detectors are considered, including subpanel effects, over excited pixels and careful intensity corrections. Problems associated with data normalization, the use of a pixel response correction from a glass standard and minimization of systematic errors are also discussed. Data from glassy GeSe{sub 2} and liquid water measured with a Perkin Elmer amorphous-Silicon detector are used to demonstrate the effectiveness of these correction procedures. This requires reduction of systematic errors in the measured intensity to around the 0.1% level.

Skinner L. B.; Parise J.; Benmore, C.

2011-10-01

94

Global analysis of proton elastic form factor data with two-photon exchange corrections  

SciTech Connect

We use the world's data on elastic electron-proton scattering and calculations of two-photon exchange effects to extract corrected values of the proton's electric and magnetic form factors over the full Q^2 range of the existing data. Our analysis combines the corrected Rosenbluth cross section and polarization transfer data, and is the first extraction of G_Ep and G_Mp including explicit two-photon exchange corrections and their associated uncertainties. In addition, we examine the angular dependence of the corrected cross sections, and discuss the possible nonlinearities of the cross section as a function of epsilon.

J. Arrington; W. Melnitchouk; J. A. Tjon

2007-09-01

95

Three-Dimensional Thermal Boundary Layer Corrections for Circular Heat Flux Gauges Mounted in a Flat Plate with a Surface Temperature Discontinuity  

NASA Technical Reports Server (NTRS)

Three-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been performed in an effort to determine thermal boundary layer correction factors for circular convective heat flux gauges (such as Schmidt-Boelter and plug type)mounted flush in a flat plate subjected to a stepwise surface temperature discontinuity. Turbulent flow solutions with temperature-dependent properties are obtained for a free stream Reynolds number of 1E6, and freestream Mach numbers of 2 and 4. The effect of gauge diameter and the plate surface temperature have been investigated. The 3-D CFD results for the heat flux correction factors are compared to quasi-21) results deduced from constant property integral solutions and also 2-D CFD analysis with both constant and variable properties. The role of three-dimensionality and of property variations on the heat flux correction factors has been demonstrated.

Kandula, M.; Haddad, G. F.; Chen, R.-H.

2006-01-01

96

Effective temperatures and bolometric corrections for some galactic Wolf-Rayet stars from absolute spectrophotometry  

NASA Astrophysics Data System (ADS)

The author presents the absolute continuum fluxes of Wolf-Rayet stars measured in the region ??3100 - 8090 by a two channel scanner built up cooperatively by the Observatoire of Lyon and the Laboratoire d'Astronomie Spatiale (L.A.S.). The dereddened fluxes together with IUE and ANS ultraviolet data are compared to those of Kurucz's LTE model atmospheres in order to derive effective temperatures and bolometric corrections. The resulting effective temperatures and bolometric corrections for these stars are found to range from 25,000 to 32,700K, and from B.C. = -2.5 to -3.7 mag. respectively.

Woo, Jong Ok

97

A New High-precision Correction Method of Temperature Distribution in Model Stellar Atmospheres  

NASA Astrophysics Data System (ADS)

The main features of the temperature correction methods, suggested and used in modeling of plane-parallel stellar atmospheres, are discussed. The main features of the new method are described. Derivation of the formulae for a version of the Unsld-Lucy method, used by us in the SMART (Stellar Model Atmospheres and Radiative Transport) software for modeling stellar atmospheres, is presented. The method is based on a correction of the model temperature distribution based on minimizing differences of flux from its accepted constant value and on the requirement of the lack of its gradient, meaning that local source and sink terms of radiation must be equal. The final relative flux constancy obtainable by the method with the SMART code turned out to have the precision of the order of 0.5 %. Some of the rapidly converging iteration steps can be useful before starting the high-precision model correction. The corrections of both the flux value and of its gradient, like in Unsld-Lucy method, are unavoidably needed to obtain high-precision flux constancy. A new temperature correction method to obtain high-precision flux constancy for plane-parallel LTE model stellar atmospheres is proposed and studied. The non-linear optimization is carried out by the least squares, in which the Levenberg-Marquardt correction method and thereafter additional correction by the Broyden iteration loop were applied. Small finite differences of temperature (? T/T=10-3) are used in the computations. A single Jacobian step appears to be mostly sufficient to get flux constancy of the order 10-2 %. The dual numbers and their generalization -- the dual complex numbers (the duplex numbers) -- enable automatically to get the derivatives in the nilpotent part of the dual numbers. A version of the SMART software is in the stage of refactorization to dual and duplex numbers, what enables to get rid of the finite differences, as an additional source of lowering precision of the computed results.

Sapar, A.; Poolame, R.; Sapar, L.

98

A low-cost four-switch BLDC motor drive with active power factor correction  

Microsoft Academic Search

This paper presents a high-performance low-cost brushless DC (BLDC) motor drive for commercial and residential applications. The proposed drive employs fewer number of switches than the conventional converter and incorporates an active power factor correction feature which results in sinusoidal input current at close to unity power factor. The proposed converter has bidirectional capability, which improves speed control features of

S. M. Madani; Lei Hao; H. A. Toliyat

2002-01-01

99

A digital power factor correction (PFC) control strategy optimized for DSP  

Microsoft Academic Search

A predictive algorithm for digital control power factor correction (PFC) is presented in this paper. Based on this algorithm, all of the duty cycles required to achieve unity power factor in one half line period are calculated in advance by digital signal processors (DSP). A boost converter controlled by these precalculated duty cycles can achieve sinusoidal current waveform. One main

Wanfeng Zhang; Guang Feng; Yan-Fei Liu; Bin Wu

2004-01-01

100

Statistical Correction of Air Temperature Forecasts for City and Road Weather Applications  

NASA Astrophysics Data System (ADS)

The method for statistical correction of air /road surface temperatures forecasts was developed based on analysis of long-term time-series of meteorological observations and forecasts (from HIgh Resolution Limited Area Model & Road Conditions Model; 3 km horizontal resolution). It has been tested for May-Aug 2012 & Oct 2012 - Mar 2013, respectively. The developed method is based mostly on forecasted meteorological parameters with a minimal inclusion of observations (covering only a pre-history period). Although the st iteration correction is based taking into account relevant temperature observations, but the further adjustment of air and road temperature forecasts is based purely on forecasted meteorological parameters. The method is model independent, e.g. it can be applied for temperature correction with other types of models having different horizontal resolutions. It is relatively fast due to application of the singular value decomposition method for matrix solution to find coefficients. Moreover, there is always a possibility for additional improvement due to extra tuning of the temperature forecasts for some locations (stations), and in particular, where for example, the MAEs are generally higher compared with others (see Gilet et al., 2014). For the city weather applications, new operationalized procedure for statistical correction of the air temperature forecasts has been elaborated and implemented for the HIRLAM-SKA model runs at 00, 06, 12, and 18 UTCs covering forecast lengths up to 48 hours. The procedure includes segments for extraction of observations and forecast data, assigning these to forecast lengths, statistical correction of temperature, one-&multi-days statistical evaluation of model performance, decision-making on using corrections by stations, interpolation, visualisation and storage/backup. Pre-operational air temperature correction runs were performed for the mainland Denmark since mid-April 2013 and shown good results. Tests also showed that the CPU time required for the operational procedure is relatively short (less than 15 minutes including a large time spent for interpolation). These also showed that in order to start correction of forecasts there is no need to have a long-term pre-historical data (containing forecasts and observations) and, at least, a couple of weeks will be sufficient when a new observational station is included and added to the forecast point. Note for the road weather application, the operationalization of the statistical correction of the road surface temperature forecasts (for the RWM system daily hourly runs covering forecast length up to 5 hours ahead) for the Danish road network (for about 400 road stations) was also implemented, and it is running in a test mode since Sep 2013. The method can also be applied for correction of the dew point temperature and wind speed (as a part of observations/ forecasts at synoptical stations), where these both meteorological parameters are parts of the proposed system of equations. The evaluation of the method performance for improvement of the wind speed forecasts is planned as well, with considering possibilities for the wind direction improvements (which is more complex due to multi-modal types of such data distribution). The method worked for the entire domain of mainland Denmark (tested for 60 synoptical and 395 road stations), and hence, it can be also applied for any geographical point within this domain, as through interpolation to about 100 cities' locations (for Danish national byvejr forecasts). Moreover, we can assume that the same method can be used in other geographical areas. The evaluation for other domains (with a focus on Greenland and Nordic countries) is planned. In addition, a similar approach might be also tested for statistical correction of concentrations of chemical species, but such approach will require additional elaboration and evaluation.

Mahura, Alexander; Petersen, Claus; Sass, Bent; Gilet, Nicolas

2014-05-01

101

Comparison between CARS and corrected thermocouple temperature measurements in a diffusion flame  

SciTech Connect

Coherent anti-Stokes Raman spectroscopy (CARS) has been used to obtain radial temperature profiles in an axisymmetric methane diffusion flame. Temperatures were obtained from analysis of background-free nitrogen Q- and O-branch spectra. The spectra were analyzed with a nonlinear least-squares CARS fitting program and compared to measurements from radiation- and conduction-corrected thermocouples. Excellent agreement was obtained in regions of relatively constant temperature, whereas improved CARS spatial resolution was required to obtain agreement near steep temperature gradients.

Farrow, R.L.; Mattern, P.L.; Rahn, L.A.

1982-09-01

102

Color reproduction error correction for color temperature conversion in PDP-TV  

Microsoft Academic Search

It is often desirable that manufacturers and users can convert the reference white of display into the preferred color temperature that is one of representative color characteristics of a light source. An efficient method of correcting color reproduction error is proposed for displaying the NTSC-based video signal in plasma display panel televisions (PDP-TVs) and is also shown to be successfully

Hyun-Chul Do; Sung-Il Chien; Ki-Duck Cho; Heung-Sik Tae

2003-01-01

103

Correcting land surface temperature measurements for directional emissivity over 3D structured vegetation  

Microsoft Academic Search

The emissivity variation of the land surface is the most difficult effect to correct for when retrieving land surface temperature (LST) from satellite measurements. This is not only because of the emissivity inter-pixel variability, but also because each individual pixel is a combination of different surface types with different emissivies. For different illumination-observation geometries, this heterogeneity leads to different ensemble

Yunyue Yu; Ana C. Pinheiro; Jeffrey L. Privette

2006-01-01

104

OBSERVATIONS OF SIMILARITY THEORY STABILITY CORRECTION TERMS FOR MOMENTUM AND TEMPERATURE, OVER AGRICULTURAL FIELDS AND FORESTS.  

EPA Science Inventory

Many observations of temperature and wind speed profiles have been taken over "ideal" terrain and analyzed to develop the stability correction terms which are commonly used in the application of similarity theory. Fewer observations have been taken and analyzed in this manner ov...

105

Study on the correction model of aero-engine exhaust gas temperature  

Microsoft Academic Search

Therefore, the measure gas path parameters must be standardized into the value under the external environment which was same to baseline, the process was called performance corrected process. The standardized model of aero-engine exhaust gas temperature (EGT) was analyzed in this paper, and the new standardized model based on core function different from the experimental test bed of aircraft maintenance

Zhi-quan Cui; Lin; Shi-sheng Zhong; Ti-chun Wang

2011-01-01

106

Implementation of Coupled Skin Temperature Analysis and Bias Correction in a Global Atmospheric Data Assimilation System  

NASA Technical Reports Server (NTRS)

The NASA/NCAR Finite Volume GCM (fvGCM) with the NCAR CLM (Community Land Model) version 2.0 was integrated into the NASA/GMAO Finite Volume Data Assimilation System (fvDAS). A new method was developed for coupled skin temperature assimilation and bias correction where the analysis increment and bias correction term is passed into the CLM2 and considered a forcing term in the solution to the energy balance. For our purposes, the fvDAS CLM2 was run at 1 deg. x 1.25 deg. horizontal resolution with 55 vertical levels. We assimilate the ISCCP-DX (30 km resolution) surface temperature product. The atmospheric analysis was performed 6-hourly, while the skin temperature analysis was performed 3-hourly. The bias correction term, which was updated at the analysis times, was added to the skin temperature tendency equation at every timestep. In this presentation, we focus on the validation of the surface energy budget at the in situ reference sites for the Coordinated Enhanced Observation Period (CEOP). We will concentrate on sites that include independent skin temperature measurements and complete energy budget observations for the month of July 2001. In addition, MODIS skin temperature will be used for validation. Several assimilations were conducted and preliminary results will be presented.

Radakovich, Jon; Bosilovich, M.; Chern, Jiun-dar; daSilva, Arlindo

2004-01-01

107

Skin Temperature Analysis and Bias Correction in a Coupled Land-Atmosphere Data Assimilation System  

NASA Technical Reports Server (NTRS)

In an initial investigation, remotely sensed surface temperature is assimilated into a coupled atmosphere/land global data assimilation system, with explicit accounting for biases in the model state. In this scheme, an incremental bias correction term is introduced in the model's surface energy budget. In its simplest form, the algorithm estimates and corrects a constant time mean bias for each gridpoint; additional benefits are attained with a refined version of the algorithm which allows for a correction of the mean diurnal cycle. The method is validated against the assimilated observations, as well as independent near-surface air temperature observations. In many regions, not accounting for the diurnal cycle of bias caused degradation of the diurnal amplitude of background model air temperature. Energy fluxes collected through the Coordinated Enhanced Observing Period (CEOP) are used to more closely inspect the surface energy budget. In general, sensible heat flux is improved with the surface temperature assimilation, and two stations show a reduction of bias by as much as 30 Wm(sup -2) Rondonia station in Amazonia, the Bowen ratio changes direction in an improvement related to the temperature assimilation. However, at many stations the monthly latent heat flux bias is slightly increased. These results show the impact of univariate assimilation of surface temperature observations on the surface energy budget, and suggest the need for multivariate land data assimilation. The results also show the need for independent validation data, especially flux stations in varied climate regimes.

Bosilovich, Michael G.; Radakovich, Jon D.; daSilva, Arlindo; Todling, Ricardo; Verter, Frances

2006-01-01

108

Assessing bias corrections in historical sea surface temperature using a climate model  

NASA Astrophysics Data System (ADS)

Analyses of simulations of variations in global and large-regional land surface air temperature (LSAT) for 1872-1998 using the HadAM3 atmospheric general circulation model are reported. The analyses are designed to test the accuracy of bias corrections to sea-surface temperature (SST) used in the Hadley Centre's global sea ice and SST (GISST3.1) data set, the more recent Hadley Centre sea ice and SST (HadISST) data set, and in the underlying Met Office historical SST (MOHSST and HadSST1) data sets. The tests are important because SST corrections considerably affect estimates of the magnitude of global warming since the late 19th century. Two ensembles of simulations were created using GISST3.1 as the lower boundary condition. The first ensemble, of six integrations, was forced using GISST with bias-corrections applied from 1871 until 1941, and was continued with no bias corrections to 1998. A second ensemble of four integrations, for 1871 to 1941, was forced with uncorrected GISST data. Simulations with uncorrected GISST show a substantial and often highly significant cold bias in simulated global and large-regional annual mean LSAT changes before 1942 relative to a 1946-65 reference period. By contrast, corrected SST data led to simulations of LSAT changes that are generally insignificantly different from those of observed LSAT in most regions before 1942. Tests on extratropical hemispheric scales generally validate the seasonal variation of the bias corrections, though less clearly before 1890 in some seasons. Issues about the quality of the LSAT data are raised by the results in a couple of regions. Over Australia, the model may have reconstructed LSAT changes using bias-corrected GISST with greater accuracy than the observations before about 1910.

Folland, Chris

2005-06-01

109

Correction factor for ablation algorithms used in corneal refractive surgery with gaussian-profile beams  

NASA Astrophysics Data System (ADS)

We provide a correction factor to be added in ablation algorithms when a Gaussian beam is used in photorefractive laser surgery. This factor, which quantifies the effect of pulse overlapping, depends on beam radius and spot size. We also deduce the expected post-surgical corneal radius and asphericity when considering this factor. Data on 141 eyes operated on LASIK (laser in situ keratomileusis) with a Gaussian profile show that the discrepancy between experimental and expected data on corneal power is significantly lower when using the correction factor. For an effective improvement of post-surgical visual quality, this factor should be applied in ablation algorithms that do not consider the effects of pulse overlapping with a Gaussian beam.

Jimenez, Jose Ramn; Gonzlez Anera, Rosario; Jimnez del Barco, Luis; Hita, Enrique; Prez-Ocn, Francisco

2005-01-01

110

Three-dimensional Correction of the Stress Intensity Factor for Plate with a Notch  

Microsoft Academic Search

The 3D effects of the 2D mode I stress intensity factor for the plate with a V-shaped straight through-thickness notch are\\u000a investigated by the finite element method and three-dimensional thicknessdependent correction of SIF is suggested. The correction\\u000a relies on the assumed relationship between the SIF and the constraint factor (out-of-plane degree of freedom). The 3D finite\\u000a element mesh generator combining

Rimantas Ka?ianauskas; Mroz zenon; Vladislav arnovskij; Eugeniu Stupak

2005-01-01

111

Equivalence of computer codes for calculation of coincidence summing correction factors.  

PubMed

The aim of the study was to check for equivalence of computer codes that can perform calculations of true coincidence summing correction factors. All calculations were performed for a set of well-defined detector and sample parameters, without any reference to empirical data. For a p-type detector model the application of different codes resulted in satisfactory agreement in the calculated correction factors. For high-efficiency geometries in combination with an n-type detector and a radionuclide emitting abundant X-rays the results were scattered. PMID:24332343

Vidmar, T; Capogni, M; Hult, M; Hurtado, S; Kastlander, J; Lutter, G; Lpy, M-C; Martinkovi?, J; Ramebck, H; Sima, O; Tzika, F; Vidmar, G

2014-05-01

112

Shear Correction Factors in Creep-Damage Analysis of Beams, Plates and Shells  

NASA Astrophysics Data System (ADS)

Modern design rules for thin-walled structures which operate at elevated temperatures are based on the demand that the creep and may be the damage behaviour should be taken into account. In the last four decades various models including the scalar or tensor valued hardening and damage variables are established. These models reflect the influence of the deformation or the damage induced anisotropy on the creep response. One problem in creep analysis of thin-walled structures is the selection of the structural mechanics model which has to be adequate to the choice of the constitutive equations. Considering complex loading conditions the structural mechanics model has to reflect for instance the different constitutive behaviour in tension and compression. Below the applicability of classical engineering models for beams, plates and shells to the creep-damage analysis is discussed. It will be shown that a first improvement of the classical approach can be given within the assumptions of the first order shear deformation theory. Based on the beam equations we demonstrate that the shear correction factors have to be modified within the time-step analysis.

Altenbach, Holm; Naumenko, Konstantin

113

NOTE: Monte Carlo simulation of correction factors for IAEA TLD holders  

NASA Astrophysics Data System (ADS)

The IAEA standard thermoluminescent dosimeter (TLD) holder has been developed for the IAEA/WHO TLD postal dose program for audits of high-energy photon beams, and it is also employed by the ESTRO-QUALity assurance network (EQUAL) and several national TLD audit networks. Factors correcting for the influence of the holder on the TL signal under reference conditions have been calculated in the present work from Monte Carlo simulations with the PENELOPE code for 60Co ?-rays and 4, 6, 10, 15, 18 and 25 MV photon beams. The simulation results are around 0.2% smaller than measured factors reported in the literature, but well within the combined standard uncertainties. The present study supports the use of the experimentally obtained holder correction factors in the determination of the absorbed dose to water from the TL readings; the factors calculated by means of Monte Carlo simulations may be adopted for the cases where there are no measured data.

Hultqvist, Martha; Fernndez-Varea, Jos M.; Izewska, Joanna

2010-03-01

114

SU(3) corrections to B ? Dl overline? form factors at O( {1}/{M})  

NASA Astrophysics Data System (ADS)

We compute the O( {1}/{M}, m s) heavy quark and SU(3) corrections to overlineBs ? D se? form factors. In the limit of vanishing light quark mass, overlineBs ? D se? form factors are given in terms of the the overlineB ? De? form factors, the leading order chiral parameter g, and two O( {1}/{M}) chiral parameters g1 and g2. All the chiral parameters can be extracted, in principle, from other heavy meson decays. Analytic counterterms proportional to the strange quark mass are presented for completeness, but no predictive power remains when they are included. Anomalously large loop corrections warn of poor convergence of the heavy quark chiral symmetry expansion for these processes. This suggests that naive extrapolations of overlineB ? D form factors relying on heavy quark and chiral symmetries, as often used in monte carlo simulations of lattice QCD, may incur large errors.

Boyd, C. Glenn; Grinstein, Benjamn

1995-02-01

115

Calculations of electron fluence correction factors using the Monte Carlo code PENELOPE  

Microsoft Academic Search

In electron-beam dosimetry, plastic phantom materials may be used instead of water for the determination of absorbed dose to water. A correction factor ?waterplastic is then needed for converting the electron fluence in the plastic phantom to the fluence at an equivalent depth in water. The recommended values for this factor given by AAPM TG-25 (1991 Med. Phys.18 73109) and

E A Siegbahn; B Nilsson; J M Fernndez-Varea; P Andreo

2003-01-01

116

Calculations of electron fluence correction factors using the Monte Carlo code PENELOPE  

Microsoft Academic Search

In electron-beam dosimetry, plastic phantom materials may be used instead of water for the determination of absorbed dose to water. A correction factor phiwaterplastic is then needed for converting the electron fluence in the plastic phantom to the fluence at an equivalent depth in water. The recommended values for this factor given by AAPM TG-25 (1991 Med. Phys. 18 73-109)

E. A. Siegbahn; B. Nilsson; J. M. Fernndez-Varea; P. Andreo

2003-01-01

117

Simulation of a Wireless Power Transfer System for Electric Vehicles with Power Factor Correction  

SciTech Connect

Wireless power transfer has been a popular topic of recent research. Most research has been done to address the limitations of coil-to-coil efficiency. However, little has been done to address the problem associated with the low input power factor with which the systems operate. This paper details the steps taken to analyze a wireless power transfer system from the view of the power grid under a variety of loading conditions with and without power factor correction.

Pickelsimer, Michael C [ORNL; Tolbert, Leon M [ORNL; Ozpineci, Burak [ORNL; Miller, John M [ORNL

2012-01-01

118

A novel PWM scheme for single-phase three-level power-factor-correction circuit  

Microsoft Academic Search

This paper presents a control scheme for a single-phase AC-to-DC power converter with three-level pulsewidth modulation. A single-phase power-factor-correction circuit is proposed to improve the power quality. The hysteresis current control technique for a diode bridge, with two power switches is adopted to achieve a high power factor and low harmonic distortion. A control scheme is presented where the line

Bor-Ren Lin; Hsin-Hung Lu

2000-01-01

119

A new scheme for power factor correction and active filtering for six-pulse converters loads  

Microsoft Academic Search

This paper presents a novel harmonic-free power factor correction (PFC) topology based on T-type active power filter (APF), which is dedicated for power factor improvement and harmonic filtering for six-pulse converter loads. The cascaded controller structure is adopted for the proposed system, namely, the inner current loop and outer voltage loop. The current-loop control scheme is based on a decoupled

Y. HAN; M. M. KHAN; L. XU; G. YAO; L. ZHOU; C. CHEN

120

Aminoglycoside Dosing Weight Correction Factors for Patients of Various Body Sizes  

Microsoft Academic Search

Prior investigations have suggested the use of a dosing weight correction factor of ideal body weight (IBW) plus 40% excess body weight (EBW, where EBW 5total body weight (TBW) 2IBW) to determine the weight to use for aminoglycoside dosing in morbidly obese (TBW\\/IBW ratio, >2) patients. Little data are available to provide dosing information for underweight or moderately obese patients.

ANNE M. TRAYNOR; ANNE N. NAFZIGER; S. BERTINO

121

Corrected QT Intervals in Newly Admitted Geriatric Psychiatric Patients: An Examination of Risk Factors  

Microsoft Academic Search

Objectives: The primary objective of this study was to determine the incidence of prolonged corrected QT (QTc) intervals in a population of geriatric psychiatry inpatients. Our secondary objective was to examine the associations between prolonged QTc intervals and risk factors identified as determinants in prolonging the QTc interval. Methods: We identified all geriatric patients (aged 60 years and older) who

Jane Dumontet; Rhonda Malyuk; Gary Kiang; Ric M Procyshyn

122

A DSP based controller for power factor correction (PFC) in a rectifier circuit  

Microsoft Academic Search

In this paper a digital signal processor (DSP) based power factor correction (PFC) scheme is presented. A dual-loop controller is designed to control the average input AC current as well as DC bus voltage. The DSP controller is implemented and tested. Design methodologies and trade-offs such as discrete-time implementation methods are also presented

M. Fu; Q. Chen

2001-01-01

123

A comparison of high power single-phase power factor correction pre-regulators  

Microsoft Academic Search

In this paper, a comparison of three high power single-phase power factor correction (PFC) pre-regulators is proposed. The topologies discussed are the boost converter, the interleaved boost converter and the dual boost converter. The control system used to perform the PFC is based in predictive current control laws and an algorithm to detect the conduction modes is also used, once

Fernando Beltrame; Leandro Roggia; Luciano Schuch; Jos Renes Pinheiro

2010-01-01

124

Variable Universe Fuzzy Controller with Correction Factors for Ball and Beam System  

Microsoft Academic Search

Traditional fuzzy controller is a interpolator in mathematic essence. The ball and beam system has defects of steady state error and low respond speed under traditional fuzzy control method. Therefore, a variable universe fuzzy control method with correction factors is proposed in this paper to solve those problems. By adjusting the fuzzy control rule and changing the universe on real

Beibei Hou; Yan Gao

2011-01-01

125

New Power Factor Correction AC-DC Converter With Reduced Storage Capacitor Voltage  

Microsoft Academic Search

Most of single-stage power factor correction (PFC) ac-dc converters usually present a high voltage swing on the storage capacitor. That means, high size and cost of the storage capacitor is obtained. The Series Inductance Interval (SII) PFC converters allow reducing cost and size of the storage capacitor since the capacitor voltage is lower than the output voltage and, therefore, the

Antonio Lazaro; Andrs Barrado; Marina Sanz; Vicente Salas; Emilio Olias

2007-01-01

126

A comparative study on current control methods for load balancing and power factor correction using STATCOM  

Microsoft Academic Search

This paper investigates several current control methods for load balancing and power factor correction based on distribution static compensator (STATCOM). Two different configurations are considered for STATCOM; a three leg inverter, and three single phase inverters. It is assumed that the STATCOM is associated with a load that is remote from the supply. After a brief introduction, control structure based

Amin Hasanzadeh; Mostafa Parniani; S. Mohammad Reza Sadriyeh

2005-01-01

127

Development of a fuzzy logic controller for boost rectifier with active power factor correction  

Microsoft Academic Search

This paper presents the use of fuzzy logic to derive a practical control scheme for a boost rectifier with active power factor correction. The methodology integrates a fuzzy logic control technique in the feedback path and linear programming rule on controlling the duty cycle of the switch for shaping the input current waveform. The proposed approach avoids complexities associated with

Henry S. H. Chung; Eugene P. W. Tam; S. Y. R. Hui

1999-01-01

128

Control of power factor correcting boost converter without instantaneous measurement of input current  

Microsoft Academic Search

This paper proposes a new control method for the constant-frequency control of power factor correcting boost power converter using a sinewave template modulated PWM signal which eliminates the need for instantaneous measurement of the line current for the switching control of the boost converter. The control strategy is based on the notion that the line current can be forced to

Seshadri Sivakumar; K. Natarajan; Rajmund Gudelewicz

1995-01-01

129

Temperature effects and corrections in volume measurements based on liquid-level detection  

SciTech Connect

Temperature changes affect volume measurements in several ways. The dimensions of the tank, and the density and level of the liquid it contains vary with temperature. In addition, the response signal of the sensor and hence the response of the liquid-level detection device may change with temperature. Level measurement devices can be grouped according to four measurement points of reference: tip of probe, response proportional to the length of probe, top of tank, and liquid surface. This paper describes the physical principles of pressure, capacitance probe, sonic reflections, and visual scales. These are representative of the four types of liquid level detection techniques. Development of the temperature correction algorithm requires that the measurement process be clearly defined, conditions or limitations specified, and that a temperature-effects test be run. Although not difficult or necessarily time-consuming to run, good practice requires a test plan following demonstrated guidelines. Measurement control procedures for remeasurement of the process solution in the tank during normal operation can provide data to validate temperature correction algorithms.

Suda, S.; Keisch, B.

1993-08-01

130

Correcting temperature and humidity forecasts using Kalman filtering: potential for agricultural protection in Northern Greece  

NASA Astrophysics Data System (ADS)

A correction method for the provision of accurate near-surface temperature and humidity forecasts is developed, based on the combination of a Kalman theory filtering technique and an empirical method with exponential smoothing. The combined method is applied on high-resolution weather forecasts provided by an operational model in Greece, over a basin in the northern part of the country, where agricultural protection is of great importance, especially due to mildew in potatoes, which represents a constant threat for farmers. The application of the method has shown that it can substantially reduce errors of the near-surface temperature and humidity forecasts provided for 2-3 days ahead in time. Based on these corrected forecasts, farmers can then schedule their fungicide spraying programs according to the expected weather, thus reducing the cost and the ecological impact of frequent preventive spraying interventions.

Anadranistakis, Manolis; Lagouvardos, Kostas; Kotroni, Vassiliki; Elefteriadis, Helias

131

A corrected procedure and consistent interpretation for temperature programmed reduction of supported MoO 3  

Microsoft Academic Search

Experiments in which bulk MoO3 has been diluted in silica or alumina reveal a corrected TPR pattern in which the bulk oxide reduces at the same temperature as the supported crystalline phase. The reduction patterns for diluted bulk MoO3, in conjunction with an XRD study of the reduction process and a recent comprehensive speciation theory have greatly assisted the assignment

John R. Regalbuto; Jin-Wook Ha

1994-01-01

132

Reconstructing past sea surface temperatures: Correcting for diagenesis of bulk marine carbonate  

Microsoft Academic Search

A numerical model which describes oxygen isotope exchange during burial and recrystallization of deep-sea carbonate is used to obtain information on how sea surface temperatures have varied in the past by correcting measured ?18O values of bulk carbonate for diagenetic overprinting. Comparison of bulk carbonate and planktonic foraminiferal ?18O records from ODP site 677A indicates that the oxygen isotopic composition

Daniel P. Schrag; Donald J. DePaolo; Frank M. Richter

1995-01-01

133

Low temperature conductivity in ferromagnetic manganite thin films: quantum corrections and inter-granular transport.  

PubMed

The interplay between inter-granular transport and quantum corrections to low temperature transport properties of La(0.67)Sr(0.33)MnO(3) (LSMO) and Nd(0.67)Sr(0.33)MnO(3) (NSMO) thin films has been discussed. All the samples exhibit characteristics of renormalized electron-electron interaction in two dimensions. The contrasting response of the low temperature transport to magnetic field in the LSMO and NSMO films is attributed to the strikingly different magnetic field sensitivity of the inter-granular transport. PMID:21825470

Mukhopadhyay, Soumik; Das, I

2009-05-01

134

Short-Wave Near-Infrared Spectrometer for Alcohol Determination and Temperature Correction  

PubMed Central

A multichannel short-wave near-infrared (SW-NIR) spectrometer module based on charge-coupled device (CCD) detection was designed. The design relied on a tungsten lamp enhanced by light emitting diodes, a fixed grating monochromator and a linear CCD array. The main advantages were high optical resolution and an optimized signal-to-noise ratio (0.24?nm and 500, resp.) in the whole wavelength range of 650 to 1100?nm. An application to alcohol determination using partial least squares calibration and the temperature correction was presented. It was found that the direct transfer method had significant systematic prediction errors due to temperature effect. Generalized least squares weighting (GLSW) method was utilized for temperature correction. After recalibration, the RMSEP found for the 25C model was 0.53% v/v and errors of the same order of magnitude were obtained at other temperatures (15, 35 and 40C). And an r2 better than 0.99 was achieved for each validation set. The possibility and accuracy of using the miniature SW-NIR spectrometer and GLSW transfer calibration method for alcohol determination at different temperatures were proven. And the analysis procedure was simple and fast, allowing a strict control of alcohol content in the wine industry.

Fu, Qingbo; Wang, Jinming; Lin, Guannan; Suo, Hui; Zhao, Chun

2012-01-01

135

Short-wave near-infrared spectrometer for alcohol determination and temperature correction.  

PubMed

A multichannel short-wave near-infrared (SW-NIR) spectrometer module based on charge-coupled device (CCD) detection was designed. The design relied on a tungsten lamp enhanced by light emitting diodes, a fixed grating monochromator and a linear CCD array. The main advantages were high optical resolution and an optimized signal-to-noise ratio (0.24?nm and 500, resp.) in the whole wavelength range of 650 to 1100?nm. An application to alcohol determination using partial least squares calibration and the temperature correction was presented. It was found that the direct transfer method had significant systematic prediction errors due to temperature effect. Generalized least squares weighting (GLSW) method was utilized for temperature correction. After recalibration, the RMSEP found for the 25C model was 0.53% v/v and errors of the same order of magnitude were obtained at other temperatures (15, 35 and 40C). And an r(2) better than 0.99 was achieved for each validation set. The possibility and accuracy of using the miniature SW-NIR spectrometer and GLSW transfer calibration method for alcohol determination at different temperatures were proven. And the analysis procedure was simple and fast, allowing a strict control of alcohol content in the wine industry. PMID:22649750

Fu, Qingbo; Wang, Jinming; Lin, Guannan; Suo, Hui; Zhao, Chun

2012-01-01

136

Monte Carlo calculated correction factors for diodes and ion chambers in small photon fields  

NASA Astrophysics Data System (ADS)

The application of small photon fields in modern radiotherapy requires the determination of total scatter factors Scp or field factors \\Omega ^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}} with high precision. Both quantities require the knowledge of the field-size-dependent and detector-dependent correction factor k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}}. The aim of this study is the determination of the correction factor k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}} for different types of detectors in a clinical 6 MV photon beam of a Siemens KD linear accelerator. The EGSnrc Monte Carlo code was used to calculate the dose to water and the dose to different detectors to determine the field factor as well as the mentioned correction factor for different small square field sizes. Besides this, the mean water to air stopping power ratio as well as the ratio of the mean energy absorption coefficients for the relevant materials was calculated for different small field sizes. As the beam source, a Monte Carlo based model of a Siemens KD linear accelerator was used. The results show that in the case of ionization chambers the detector volume has the largest impact on the correction factor k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}}; this perturbation may contribute up to 50% to the correction factor. Field-dependent changes in stopping-power ratios are negligible. The magnitude of k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}} is of the order of 1.2 at a field size of 1 1 cm2 for the large volume ion chamber PTW31010 and is still in the range of 1.05-1.07 for the PinPoint chambers PTW31014 and PTW31016. For the diode detectors included in this study (PTW60016, PTW 60017), the correction factor deviates no more than 2% from unity in field sizes between 10 10 and 1 1 cm2, but below this field size there is a steep decrease of k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}} below unity, i.e. a strong overestimation of dose. Besides the field size and detector dependence, the results reveal a clear dependence of the correction factor on the accelerator geometry for field sizes below 1 1 cm2, i.e. on the beam spot size of the primary electrons hitting the target. This effect is especially pronounced for the ionization chambers. In conclusion, comparing all detectors, the unshielded diode PTW60017 is highly recommended for small field dosimetry, since its correction factor k^{f_{clin} ,f_{msr}}_{Q_{clin} ,Q_{msr}} is closest to unity in small fields and mainly independent of the electron beam spot size.

Czarnecki, D.; Zink, K.

2013-04-01

137

Juvenile Correctional Workers' Perceptions of Suicide Risk Factors and Mental Health Issues of Incarcerated Juveniles  

PubMed Central

Correctional staff knowledge, attitudes, and perceptions of incarcerated juveniles' mental health needs, including suicide prevention, have not been studied empirically. This study measured juvenile correctional officers' knowledge and attitudes regarding suicide risk factors and mental health and substance abuse issues through administration of the Mental Health Knowledge and Attitude Test (MHKAT) before and after a staff training on suicide prevention. Seventy-six participants completed the pre- and post-training MHKAT. They demonstrated significant improvement in knowledge of and attitudes toward mental health treatment of incarcerated youth as reflected by higher post-training MHKAT scores. Findings suggest that correctional staff are receptive to increasing knowledge of critical mental health issues. Studies of the retention and implementation of this new knowledge by direct care staff over time and the optimal type and frequency of new staff training and continuing education are indicated.

Penn, Joseph V.; Esposito, Christianne; Stein, L. A. R.; Lacher-Katz, Molly; Spirito, Anthony

2009-01-01

138

Diaphragm correction factors for free-air chamber standards for air kerma in x-rays  

NASA Astrophysics Data System (ADS)

At present, only a correction factor for photon transmission, kl, is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate kl for the BIPM standards and new correction factors are calculated for photon scatter and for fluorescence production in the diaphragm. An additional effect arising from electrons emitted from the diaphragm is shown to be significant at the highest photon energies. The results for the radiation qualities used for international comparisons give a combined diaphragm correction factor kdia = 0.9980(3) for the BIPM medium-energy standard at 250 kV. This is significantly different from the factor kl = 0.9996(1) in use at present and it might be concluded that differences are likely to exist for all free-air chamber standards. The effect of using a conical taper at the downstream edge of the diaphragm is shown to be negligible for these radiation qualities.

Burns, D. T.; Kessler, C.

2009-05-01

139

Diaphragm correction factors for free-air chamber standards for air kerma in x-rays.  

PubMed

At present, only a correction factor for photon transmission, k(l), is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate k(l) for the BIPM standards and new correction factors are calculated for photon scatter and for fluorescence production in the diaphragm. An additional effect arising from electrons emitted from the diaphragm is shown to be significant at the highest photon energies. The results for the radiation qualities used for international comparisons give a combined diaphragm correction factor k(dia) = 0.9980(3) for the BIPM medium-energy standard at 250 kV. This is significantly different from the factor k(l) = 0.9996(1) in use at present and it might be concluded that differences are likely to exist for all free-air chamber standards. The effect of using a conical taper at the downstream edge of the diaphragm is shown to be negligible for these radiation qualities. PMID:19351980

Burns, D T; Kessler, C

2009-05-01

140

Stress Intensity Factor Plasticity Correction for Flaws in Stress Concentration Regions  

SciTech Connect

Plasticity corrections to elastically computed stress intensity factors are often included in brittle fracture evaluation procedures. These corrections are based on the existence of a plastic zone in the vicinity of the crack tip. Such a plastic zone correction is included in the flaw evaluation procedure of Appendix A to Section XI of the ASME Boiler and Pressure Vessel Code. Plasticity effects from the results of elastic and elastic-plastic explicit flaw finite element analyses are examined for various size cracks emanating from the root of a notch in a panel and for cracks located at fillet fadii. The results of these caluclations provide conditions under which the crack-tip plastic zone correction based on the Irwin plastic zone size overestimates the plasticity effect for crack-like flaws embedded in stress concentration regions in which the elastically computed stress exceeds the yield strength of the material. A failure assessment diagram (FAD) curve is employed to graphically c haracterize the effect of plasticity on the crack driving force. The Option 1 FAD curve of the Level 3 advanced fracture assessment procedure of British Standard PD 6493:1991, adjusted for stress concentration effects by a term that is a function of the applied load and the ratio of the local radius of curvature at the flaw location to the flaw depth, provides a satisfactory bound to all the FAD curves derived from the explicit flaw finite element calculations. The adjusted FAD curve is a less restrictive plasticity correction than the plastic zone correction of Section XI for flaws embedded in plastic zones at geometric stress concentrators. This enables unnecessary conservatism to be removed from flaw evaluation procedures that utilize plasticity corrections.

Friedman, E.; Wilson, W.K.

2000-02-01

141

Correcting for focal-plane-array temperature dependence in microbolometer infrared cameras lacking thermal stabilization  

NASA Astrophysics Data System (ADS)

Advances in microbolometer detectors have led to the development of infrared cameras that operate without active temperature stabilization. The response of these cameras varies with the temperature of the camera's focal plane array (FPA). This paper describes a method for stabilizing the camera's response through software processing. This stabilization is based on the difference between the camera's response at a measured temperature and at a reference temperature. This paper presents the mathematical basis for such a correction and demonstrates the resulting accuracy when applied to a commercially available long-wave infrared camera. The stabilized camera was then radiometrically calibrated so that the digital response from the camera could be related to the radiance or temperature of objects in the scene. For FPA temperature deviations within 7.2C changing by 0.5C/min, this method produced a camera calibration with spatial-temporal rms variability of 0.21C, yielding a total calibration uncertainty of 0.38C limited primarily by the 0.32C uncertainty in the blackbody source emissivity and temperature.

Nugent, Paul W.; Shaw, Joseph A.; Pust, Nathan J.

2013-06-01

142

Correcting infrared satellite estimates of sea surface temperature for atmospheric water vapor attenuation  

NASA Technical Reports Server (NTRS)

A new satellite sea surface temperature (SST) algorithm is developed that uses nearly coincident measurements from the microwave special sensor microwave imager (SSM/I) to correct for atmospheric moisture attenuation of the infrared signal from the advanced very high resolution radiometer (AVHRR). This new SST algorithm is applied to AVHRR imagery from the South Pacific and Norwegian seas, which are then compared with simultaneous in situ (ship based) measurements of both skin and bulk SST. In addition, an SST algorithm using a quadratic product of the difference between the two AVHRR thermal infrared channels is compared with the in situ measurements. While the quadratic formulation provides a considerable improvement over the older cross product (CPSST) and multichannel (MCSST) algorithms, the SSM/I corrected SST (called the water vapor or WVSST) shows overall smaller errors when compared to both the skin and bulk in situ SST observations. Applied to individual AVHRR images, the WVSST reveals an SST difference pattern (CPSST-WVSST) similar in shape to the water vapor structure while the CPSST-quadratic SST difference appears unrelated in pattern to the nearly coincident water vapor pattern. An application of the WVSST to week-long composites of global area coverage (GAC) AVHRR data demonstrates again the manner in which the WVSST corrects the AVHRR for atmospheric moisture attenuation. By comparison the quadratic SST method underestimates the SST corrections in the lower latitudes and overestimates the SST in th e higher latitudes. Correlations between the AVHRR thermal channel differences and the SSM/I water vapor demonstrate the inability of the channel difference to represent water vapor in the midlatitude and high latitudes during summer. Compared against drifting buoy data the WVSST and the quadratic SST both exhibit the same general behavior with the relatively small differences with the buoy temperatures.

Emery, William J.; Yu, Yunyue; Wick, Gary A.; Schluessel, Peter; Reynolds, Richard W.

1994-01-01

143

Correcting infrared satellite estimates of sea surface temperature for atmospheric water vapor attenuation  

NASA Astrophysics Data System (ADS)

A new satellite sea surface temperature (SST) algorithm is developed that uses nearly coincident measurements from the microwave special sensor microwave imager (SSM/I) to correct for atmospheric moisture attenuation of the infrared signal from the advanced very high resolution radiometer (AVHRR). This new SST algorithm is applied to AVHRR imagery from the South Pacific and Norwegian seas, which are then compared with simultaneous in situ (ship based) measurements of both skin and bulk SST. In addition, an SST algorithm using a quadratic product of the difference between the two AVHRR thermal infrared channels is compared with the in situ measurements. While the quadratic formulation provides a considerable improvement over the older cross product (CPSST) and multichannel (MCSST) algorithms, the SSM/I corrected SST (called the water vapor or WVSST) shows overall smaller errors when compared to both the skin and bulk in situ SST observations. Applied to individual AVHRR images, the WVSST reveals an SST difference pattern (CPSST-WVSST) similar in shape to the water vapor structure while the CPSST-quadratic SST difference appears unrelated in pattern to the nearly coincident water vapor pattern. An application of the WVSST to week-long composites of global area coverage (GAC) AVHRR data demonstrates again the manner in which the WVSST corrects the AVHRR for atmospheric moisture attenuation. By comparison the quadratic SST method underestimates the SST corrections in the lower latitudes and overestimates the SST in the higher latitudes. Correlations between the AVHRR thermal channel differences and the SSM/I water vapor demonstrate the inability of the channel difference to represent water vapor in the midlatitude and high latitudes during summer. Compared against drifting buoy data the WVSST and the quadratic SST both exhibit the same general behavior with relatively small differences with the buoy temperatures.

Emery, William J.; Yu, Yunyue; Wick, Gary A.; Schluessel, Peter; Reynolds, Richard W.

1994-03-01

144

Photoelastic correction factor for fiber strain measurements in a cable under tensile load  

Microsoft Academic Search

There has been a large variation among reported values for photo-elastic correction factor (K). The nonlinearity of group index versus strain plot was demonstrated to be the cause of the inconsistency. Based on this finding, it is concluded that the K value should be in the range of 1.26-1.30 when the fiber strain is less than 0.6% and 1.22-1.24 when

K. Abe; K. Yoshida; O. Daneshvar; J. J. Carr

1995-01-01

145

Current waveform distortion in power factor correction circuits employing discontinuous-mode boost converters  

Microsoft Academic Search

For active power factor correction circuits employing discontinuous-mode boost converters, the line current will automatically follow the sinusoidal line-voltage waveform. However, due to the modulation of the input inductor current discharging time, there is certain distortion in the AC line-current waveform. It is found that the modulation of inductor current discharging time is a function of the line voltage and

Kwang-Hwa Liu; Yung-Lin Lin

1989-01-01

146

Totem-Pole Power-Factor-Correction Converter under Critical-Conduction-Mode Interleaved Operation  

NASA Astrophysics Data System (ADS)

This paper proposes a new power-factor-correction (PFC) topology, and explains its operation principle, its control mechanism, related application problems followed by experimental results. In this proposed topology, critical-conduction-mode (CRM) interleaved technique is applied to a bridgeless PFC in order to achieve high efficiency by combining benefits of each topology. This application is targeted toward low to middle power applications that normally employs continuous-conduction-mode boost converter.

Firmansyah, Eka; Tomioka, Satoshi; Abe, Seiya; Shoyama, Masahito; Ninomiya, Tamotsu

147

Zero-Current-Switch Quasi-Resonant Boost Converter in Power Factor Correction Applications  

Microsoft Academic Search

A modified zero-current-switched quasi-resonant (ZCS-QR) boost converter is employed in a power factor correction (PFC) application. The main goal is to achieve a small-size low-noise PFC circuit based on single-switch boost topology. A clamp diode has been added to avoid the voltage ringing problem that is originally generated across the ZCS-QR switch during its turn-off period. The converter operation states

E. Firmansyah; S. Tomioka; S. Abe; M. Shoyama; T. Ninomiya

2009-01-01

148

Single-phase three-level converter for power factor correction  

Microsoft Academic Search

A single-phase half-bridge switching mode rectifier is presented to draw a sinusoidal line current, to achieve power factor correction and to maintain the dc-link voltage constant. Four active switches with voltage stress of half dc bus voltage are used in the proposed rectifier to generate a unipolar PWM voltage waveform on the ac terminal voltage. There is no clamping diode

Bor-ren Lin; Tsung-yu Yang

2004-01-01

149

An integral battery charger with Power Factor Correction for electric scooter  

Microsoft Academic Search

An integral battery charger is proposed for an electric scooter with Li-Ion batteries and Interior-permanent-magnet (IPM) traction motor. The battery charger is integrated in the power hardware of the scooter, with the IPM traction drive that operates as three-phase dc-dc converter with power factor correction (PFC) capability. The control of the PFC battery charger is also integrated into the traction

Gianmario Pellegrino; Eric Armando; Paolo Guglielmi

2009-01-01

150

An Integral Battery Charger With Power Factor Correction for Electric Scooter  

Microsoft Academic Search

This paper presents an integral battery charger for an electric scooter with high voltage batteries and interior-permanent-magnet motor traction drive. The battery charger is derived from the power hardware of the scooter, with the ac motor drive that operates as three-phase boost rectifier with power factor correction capability. The control of the charger is also integrated into the scooter control

Gianmario Pellegrino; Eric Armando; Paolo Guglielmi

2010-01-01

151

ccSVM: correcting Support Vector Machines for confounding factors in biological data classification  

PubMed Central

Motivation: Classifying biological data into different groups is a central task of bioinformatics: for instance, to predict the function of a gene or protein, the disease state of a patient or the phenotype of an individual based on its genotype. Support Vector Machines are a wide spread approach for classifying biological data, due to their high accuracy, their ability to deal with structured data such as strings, and the ease to integrate various types of data. However, it is unclear how to correct for confounding factors such as population structure, age or gender or experimental conditions in Support Vector Machine classification. Results: In this article, we present a Support Vector Machine classifier that can correct the prediction for observed confounding factors. This is achieved by minimizing the statistical dependence between the classifier and the confounding factors. We prove that this formulation can be transformed into a standard Support Vector Machine with rescaled input data. In our experiments, our confounder correcting SVM (ccSVM) improves tumor diagnosis based on samples from different labs, tuberculosis diagnosis in patients of varying age, ethnicity and gender, and phenotype prediction in the presence of population structure and outperforms state-of-the-art methods in terms of prediction accuracy. Availability: A ccSVM-implementation in MATLAB is available from http://webdav.tuebingen.mpg.de/u/karsten/Forschung/ISMB11_ccSVM/. Contact: limin.li@tuebingen.mpg.de; karsten.borgwardt@tuebingen.mpg.de

Li, Limin; Rakitsch, Barbara; Borgwardt, Karsten

2011-01-01

152

Next-to-leading-order corrections to exclusive processes in k{sub T} factorization  

SciTech Connect

We calculate next-to-leading-order corrections to exclusive processes in the k{sub T} factorization theorem, taking {pi}{gamma}*{yields}{gamma} as an example. Partons off shell by k{sub T}{sup 2} are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the k{sub T}-dependent hard kernel as their difference. The gauge invariance of the hard kernel is then proven to all orders by induction. The light-cone singularities in the k{sub T}-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. This regularization introduces a factorization-scheme dependence into the hard kernel, which can be minimized in the standard way. Both the large double logarithms ln{sup 2}k{sub T} and ln{sup 2}x, x being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function and organized by the k{sub T} resummation and the latter absorbed into a jet function and organized by the threshold resummation. The next-to-leading-order corrections are found to be only a few percent for {pi}{gamma}*{yields}{gamma}, if setting the factorization scale to the momentum transfer from the virtual photon.

Nandi, Soumitra [Department of Physics, University of Calcutta, 92 A.P.C Road, Kolkata 700009 (India); Li Hsiangnan [Institute of Physics, Academia Sinica, Taipei, Taiwan 115 (China); Department of Physics, National Cheng-Kung University, Tainan, Taiwan 701 (China) and Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan 300 (China)

2007-08-01

153

Development of Tissue to Total Mass Correction Factor for Porites divaricata in Calcification Rate Studies  

NASA Astrophysics Data System (ADS)

One anticipated result of ocean acidification is lower calcification rates of corals. Many studies currently use the buoyant weights of coral nubbins as a means of estimating skeletal weight during non-destructive experiments. The objectives of this study, conducted at the Little Cayman Research Centre, were twofold: (1) to determine whether the purple and yellow color variations of Porites divaricata had similar tissue mass to total mass ratios; and (2) to determine a correction factor for tissue mass based on the total coral mass. T-test comparisons indicated that the tissue to total mass ratios were statistically similar for purple and yellow cohorts, thus allowing them to be grouped together within a given sample population. Linear regression analysis provided a correction factor (r2 = 0.69) to estimate the tissue mass from the total mass, which may eliminate the need to remove tissue during studies and allow subsequent testing on the same nubbins or their return to the natural environment. Additional work is needed in the development of a correction factor for P. divaricata with a higher prediction accuracy.

Cannone, T. C.; Kelly, S. K.; Foster, K.

2013-05-01

154

Main considerable factors for correct laboratory test interpretation under DOA treatment  

PubMed Central

Summary To avoid misinterpretation and mismanagement clinicians should be aware of the interference of new direct oral anticoagulants (DOA) on coagulation assays. A variety of oral anticoagulants targeting specific coagulation factors has already entered the market, and new indications for DOA will be released each year over the next few years. Due to their heterogeneous mode of action and different pharmacokinetic profile each DOA will vary in its effects on coagulations assays, and it is of current importance to recognize these variable effects. In this summary the main considerable factors for correct laboratory test interpretation under DOA treatment are described.

2013-01-01

155

Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars  

NASA Astrophysics Data System (ADS)

Broad band colors and bolometric corrections in the Johnson-Cousins-Glass system (Bessell, 1990; Bessell & Brett, 1988) have been computed from synthetic spectra from new model atmospheres of Kurucz (1995a), Castelli (1997), Plez, Brett & Nordlund (1992), Plez (1995-97), and Brett (1995a,b). These atmospheres are representative of larger grids that are currently being completed. We discuss differences between the different grids and compare theoretical color-temperature relations and the fundamental color temperature relations derived from: (a) the infrared-flux method (IRFM) for A-K stars (Blackwell & Lynas-Gray 1994; Alonso et al. 1996) and M dwarfs (Tsuji et al. 1996a); (b) lunar occultations (Ridgway et al. 1980) and (c) Michelson interferometry (Di Benedetto & Rabbia 1987; Dyck et al. 1996; Perrin et al. 1997) for K-M giants, and (d) eclipsing binaries for M dwarfs. We also compare color - color relations and color - bolometric correction relations and find good agreement except for a few colors. The more realistic fluxes and spectra of the new model grids should enable accurate population synthesis models to be derived and permit the ready calibration of non-standard photometric passbands. As well, the theoretical bolometric corrections and temperature - color relations will permit reliable transformation from observed color magnitude diagrams to theoretical HR diagrams. Tables 1-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Bessell, M. S.; Castelli, F.; Plez, B.

1998-05-01

156

[Consideration to eliminate K as a factor of correction in the Mini-Mult 82].  

PubMed

In this study, a discussion and procedure to eliminate K as a factor of correction in the MINI-MULT 82, is presented. This test was developed in Costa Rica and based on Kincannon's Mini-Mult, a short form of the Minnesota Multiphasic Personality Inventory (MMPI). However, the test has been independent from the MMPI, and it is not used as s predictor form. In consequence, the influence of factor K has been considered, either as a suppressor variable or as a contributor to improve the validity of the test. Two samples, one of non patients and other of psychiatric patients were compared using Student's t-test. To do that, the test was scored first, without the K factor and finally, using that one. The results showed statistical differences between the samples (p < 0.001) and they were stronger when the K factor was not used. This findings support the elimination of K as a factor of correction in the MINI-MULT 82. Implications and guidelines about future research, are discussed at the end. PMID:7484186

Garnier Zamora, L A; Alberto Leandro, M

1994-12-01

157

Stability correction functions for the mean wind speed and temperature in the unstable surface layer  

NASA Technical Reports Server (NTRS)

In accordance with a theoretical analysis by Kader and Yaglom, interpolation expressions are proposed for the Monin-Obukhov functions for the wind speed and temperature profiles under unstable conditions in the surface layer of the atmospheric boundary layer. The values of the parameters are adjusted to agree with earlier work under weak instability, as reviewed by Hogstrom. The resulting formulations are valid for considerably larger values of their argument than those that were hitherto available. Their advantage is that they yield concise and closed-form stability correction functions which can be readily applied in profile analysis and model calculations.

Brutsaert, Wilfried

1992-01-01

158

Implementation of the Temperature-Dependent Dark Correction in CalnicA  

NASA Astrophysics Data System (ADS)

The pipeline implementation of the temperature-dependent dark correction, previously only available to users as a WWW tool, is described. The algorithm used to generate the darksisdescribed,alongwithadescriptionofhowtheIDLcodeanddatathatareusedin the WWW tool were incorporated into the usual HST pipeline model of code+reference ?les. This implementation necessitated the creation of a new reference ?le type: the Tem- perature-Dependent Dark (TDD) ?le. The design of this ?le type allowed many of the hardconstantstoberemovedfromthecodeandputintothereference?les,allowingmore convenient and ?exible updating of the calibration parameters, if necessary.

Jedrzejewski, R.

2002-12-01

159

Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.  

PubMed

Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively. PMID:23464237

Hindasageri, V; Vedula, R P; Prabhu, S V

2013-02-01

160

Using satellite altimetry to correct mean temperature and salinity fields derived from Argo floats in the ocean regions around Australia  

NASA Astrophysics Data System (ADS)

We present results from a suite of methods using in situ temperature and salinity data, and satellite altimetric observations to obtain an enhanced set of mean fields of temperature, salinity (down to 2000-m depth) and steric height (0/2000 m) for a time-specific period (1992-2007). Firstly, the improved global sampling resulting from the introduction of the Argo program, enables a representative determination of the large-scale mean oceanic structure. However, shortcomings in the coverage remain. High variability western boundary current eddy fields, continental slope and shelf boundaries may all be below their optimal sampling requirements. We describe a simple method to supplement and improve standard spatial interpolation schemes and apply them to the available data within the waters surrounding Australia (100E-180W; 50S-10N). This region includes a major current system, the East Australian Current (EAC), complex topography, unique boundary currents such as the Leeuwin Current, and large ENSO related interannual variability in the southwest Pacific. We use satellite altimetry sea level anomalies (SLA) to directly correct sampling errors in in situ derived mean surface steric height and subsurface temperature and salinity fields. The surface correction is projected through the water column (using an empirical model) to modify the mean subsurface temperature and salinity fields. The errors inherent in all these calculations are examined. The spatial distribution of the barotropic-baroclinic balance is obtained for the region and a 'baroclinic factor' to convert the altimetry SLA into an equivalent in situ height is determined. The mean fields in the EAC region are compared with independent estimates on repeated XBT sections, a mooring array and full-depth CTD transects.

Ridgway, K. R.; Dunn, J. R.

2010-09-01

161

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

PubMed

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 rateK?a,100 and reference dose rate to waterD?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 ktot, 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?a,100 or D?w,1. The factor ktot was determined for four available (192)Ir sources and one (60)Co source with three different thimble ionization chambers. Finally, ionization chamber measurements on three ?Selectron V2 HDR sources within the Krieger-phantom were performed and K?a,100 was determined according to three different methods: 1) using a calibration factor in terms of absorbed dose to water with the global correction factor [Formula: see text] 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 [Formula: see text] with those from DGMP 13 showed that the DGMP data were systematically smaller by about 2-2.5%. The experimentally determined [Formula: see text] , based on the direct K?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 1? level of confidence of the interval of their respective uncertainties in a Gaussian distribution. The application of Monte Carlo based [Formula: see text] for the determination of K?a,100 for three ?Selectron V2 sources revealed the smallest deviation to the manufacturer's source certificate. With the calculated [Formula: see text] for a (60)Co source, the user is now able to accurately determine K?a,100 of a HDR (60)Co source via in-phantom measurement. Moreover, using the presented global correction factor [Formula: see text] , the user is able to determine the future source specification quantity D?w,1 with the same in-phantom setup. PMID:24021956

Ubrich, Frank; Wulff, Jrg; Engenhart-Cabillic, Rita; Zink, Klemens

2014-05-01

162

Correcting land surface temperature measurements for directional emissivity over 3D structured vegetation  

NASA Astrophysics Data System (ADS)

The emissivity variation of the land surface is the most difficult effect to correct for when retrieving land surface temperature (LST) from satellite measurements. This is not only because of the emissivity inter-pixel variability, but also because each individual pixel is a combination of different surface types with different emissivies. For different illumination-observation geometries, this heterogeneity leads to different ensemble (scene) emissivities. The modified geometric project (MGP) model has been demonstrated to be able to simulate such effect when the surface structural characteristics are available. In this study, we built a lookup table to correct the surface emissivity variation effect in LST retrievals. The lookup table is calculated using the MGP model and the MODTRAN radiative transfer model. The MGP model, assumes that the land surface visible to the satellite sensor is a composite of homogeneous vegetation and soil background surface types. The homogeneous or "pure" surface types and their emissivity values are adopted from Snyder's surface type classification. Our simulation procedure was designed to calculate the emissivity directional variation for multiple scenarios with different surface types, solar-view angles, tree cover fractions, and leaf area index. Analysis of the MODTRAN simulation results indicates that an error of over 1.4 K can be observed in the retrieved LST if surface emissivity directional variability is not accounted for. Several MODIS granule data were selected to evaluate the correction method. The results are compared with the current MODIS LST products.

Yu, Yunyue; Pinheiro, Ana C.; Privette, Jeffrey L.

2006-09-01

163

Planar imaging quantification using 3D attenuation correction data and Monte Carlo simulated buildup factors.  

PubMed

A new method to correct for attenuation and the buildup of scatter in planar imaging quantification is presented. The method is based on the combined use of 3D density information provided by computed tomography to correct for attenuation and the application of Monte Carlo simulated buildup factors to correct for buildup in the projection pixels. CT and nuclear medicine images were obtained for a purpose-built nonhomogeneous phantom that models the human anatomy in the thoracic and abdominal regions. The CT transverse slices of the phantom were converted to a set of consecutive density maps. An algorithm was developed that projects the 3D information contained in the set of density maps to create opposing pairs of accurate 2D correction maps that were subsequently applied to planar images acquired from a dual-head gamma camera. A comparison of results obtained by the new method and the geometric mean approach based on published techniques is presented for some of the source arrangements used. Excellent results were obtained for various source-phantom configurations used to evaluate the method. Activity quantification of a line source at most locations in the nonhomogeneous phantom produced errors of less than 2%. Additionally, knowledge of the actual source depth is not required for accurate activity quantification. Quantification of volume sources placed in foam, Perspex and aluminium produced errors of less than 7% for the abdominal and thoracic configurations of the phantom. PMID:8858727

Miller, C; Filipow, L; Jackson, S; Riauka, T

1996-08-01

164

Study of corrections to the geometrical factor in the space charge impedance for the IPNS upgrade  

SciTech Connect

Collective instabilities are an important consideration in the 2-GeV rapidly-cycling synchrotron (RCS) of the proposed 1-MW spallation neutron source upgrade due to the very high beam intensity of 1.04{times}10{sup 14} protons per pulse. Collective instabilities are intensity-dependent effects which arise due to the electromagnetic wake fields generated by the beam as it interacts with its surroundings. The interactions are characterized by the coupling impedance, which in the RCS is dominated by space charge effects. To minimize the space charge impedance, the vacuum chamber is constructed with a special wire rf shield. Estimating the longitudinal and transverse impedance due to space charge is critical for the beam stability analysis. The standard geometrical factors used to evaluate the space charge impedance assume a uniform, round, unbunched beam in a cylindrical, smooth beam pipe. Two corrections to the geometrical factors have been proposed to account separately for the wire rf-screening cage and the more realistic varying elliptical beam cross-section. These corrections are studied in the case of the RCS. It is found that including these details results in a correction of less than 20%.

Harkay, K.C.

1995-03-17

165

Bias Correction for Assimilation of Retrieved AIRS Profiles of Temperature and Humidity  

NASA Technical Reports Server (NTRS)

Atmospheric Infrared Sounder (AIRS) is a hyperspectral radiometer aboard NASA's Aqua satellite designed to measure atmospheric profiles of temperature and humidity. AIRS retrievals are assimilated into the Weather Research and Forecasting (WRF) model over the North Pacific for some cases involving "atmospheric rivers". These events bring a large flux of water vapor to the west coast of North America and often lead to extreme precipitation in the coastal mountain ranges. An advantage of assimilating retrievals rather than radiances is that information in partly cloudy fields of view can be used. Two different Level 2 AIRS retrieval products are compared: the Version 6 AIRS Science Team standard retrievals and a neural net retrieval from MIT. Before assimilation, a bias correction is applied to adjust each layer of retrieved temperature and humidity so the layer mean values agree with a short-term model climatology. WRF runs assimilating each of the products are compared against each other and against a control run with no assimilation. This paper will describe the bias correction technique and results from forecasts evaluated by validation against a Total Precipitable Water (TPW) product from CIRA and against Global Forecast System (GFS) analyses.

Blankenship, Clay; Zavodsky, Brad; Blackwell, William

2014-01-01

166

Errors in climate model daily precipitation and temperature output: time invariance and implications for bias correction  

NASA Astrophysics Data System (ADS)

When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with GCM biases varying between mean and extreme values and for different sets of historical years. Daily precipitation and maximum and minimum temperature from late 20th century simulations by four GCMs over the United States were compared to gridded observations. Using random years from the historical record we select a "base" set and a 10-yr independent "projected" set. We compare differences in biases between these sets at median and extreme percentiles. On average a base set with as few as 4 randomly-selected years is often adequate to characterize the biases in daily GCM precipitation and temperature, at both median and extreme values; 12 yr provided higher confidence that bias correction would be successful. This suggests that some of the GCM bias is time invariant. When characterizing bias with a set of consecutive years, the set must be long enough to accommodate regional low frequency variability, since the bias also exhibits this variability. Newer climate models included in the Intergovernmental Panel on Climate Change fifth assessment will allow extending this study for a longer observational period and to finer scales.

Maurer, E. P.; Das, T.; Cayan, D. R.

2013-02-01

167

Errors in climate model daily precipitation and temperature output: time invariance and implications for bias correction  

NASA Astrophysics Data System (ADS)

When correcting for biases in general circulation model (GCM) output, for example when statistically downscaling for regional and local impacts studies, a common assumption is that the GCM biases can be characterized by comparing model simulations and observations for a historical period. We demonstrate some complications in this assumption, with GCM biases varying between mean and extreme values and for different sets of historical years. Daily precipitation and maximum and minimum temperature from late 20th century simulations by four GCMs over the United States were compared to gridded observations. Using random years from the historical record we select a "base" set and a 10 yr independent "projected" set. We compare differences in biases between these sets at median and extreme percentiles. On average a base set with as few as 4 randomly-selected years is often adequate to characterize the biases in daily GCM precipitation and temperature, at both median and extreme values; 12 yr provided higher confidence that bias correction would be successful. This suggests that some of the GCM bias is time invariant. When characterizing bias with a set of consecutive years, the set must be long enough to accommodate regional low frequency variability, since the bias also exhibits this variability. Newer climate models included in the Intergovernmental Panel on Climate Change fifth assessment will allow extending this study for a longer observational period and to finer scales.

Maurer, E. P.; Das, T.; Cayan, D. R.

2013-06-01

168

A Study on the Subjective Response for Corrected Colour Temperature Conditions in a Specific Space  

Microsoft Academic Search

The luminous environment in a space is one of the key factors affecting the occupants' work performance and mood. An illuminance value is quantitatively standardised and recommended for a specific space, but correlated colour temperature (CCT) is not. Although some studies on CCT conditions have shown that higher CCT conditions appear brighter to people than lower CCT conditions, other studies

Byoung-Chul Park; Jun-Ho Chang; Yu-Sin Kim; Jae-Weon Jeong; An-Seop Choi

2010-01-01

169

Calculations of electron fluence correction factors using the Monte Carlo code PENELOPE.  

PubMed

In electron-beam dosimetry, plastic phantom materials may be used instead of water for the determination of absorbed dose to water. A correction factor phi(water)plastic is then needed for converting the electron fluence in the plastic phantom to the fluence at an equivalent depth in water. The recommended values for this factor given by AAPM TG-25 (1991 Med. Phys. 18 73-109) and the IAEA protocols TRS-381 (1997) and TRS-398 (2000) disagree, in particular at large depths. Calculations of the electron fluence have been done, using the Monte Carlo code PENELOPE, in semi-infinite phantoms of water and common plastic materials (PMMA, clear polystyrene, A-150, polyethylene, Plastic water and Solid water (WT1)). The simulations have been carried out for monoenergetic electron beams of 6, 10 and 20 MeV, as well as for a realistic clinical beam. The simulated fluence correction factors differ from the values in the AAPM and IAEA recommendations by up to 2%, and are in better agreement with factors obtained by Ding et al (1997 Med. Phys. 24 161-76) using EGS4. Our Monte Carlo calculations are also in good accordance with phi(water)plastic values measured by using an almost perturbation-free ion chamber. The important interdependence between depth- and fluence-scaling corrections for plastic phantoms is discussed. Discrepancies between the measured and the recommended values of phi(water)plastic may then be explained considering the different depth-scaling rules used. PMID:12812445

Siegbahn, E A; Nilsson, B; Fernndez-Varea, J M; Andreo, P

2003-05-21

170

Vibration Behavior of Composite Beams with Rectangular Sections Considering the Different Shear Correction Factors  

NASA Astrophysics Data System (ADS)

As is well known, there are the first and higher order shear deformation theories that involve the shear correction factor (k- factor), which appears as a coefficient in the expression for the transverse shear stress resultant, to consider the shear deformation effects with a good approximation as a result of non-uniform distribution of the shear stresses over the cross-section of the beam. Timoshenko's beam theory (TBT) accounts both the shear and rotatory inertia effects based upon the first order shear deformation theory which offers the simple and acceptable solutions. The numerical value of the k-factor which was originally proposed by Timoshenko depends upon generally both the Poisson's ratio of the material and the shape of the cross-section. Recently, especially the numerical value of the k-factor for rectangular sections is examined by both theoretical and experimental manners. Although there are no large numerical differences among the most of the theories, a few of them says that the k-factor varies obviously with the aspect ratio of rectangular sections while Timoshenko's k-factor is applicable for small aspect ratios. In this study, the effect of the different k-factors developed by Timoshenko, Cowper and Hutchinson on the in-plane free vibration of the orthotropic beams with different boundary conditions and different aspect ratios are studied numerically based on the transfer matrix method. For the first six frequencies, the relative differences of among the theories are presented by charts.

Y?ld?r?m, Vebil

171

New continuous-input current charge pump power-factor-correction electronic ballast  

SciTech Connect

Continuous-input current charge pump power-factor-correction (CIC-CPPFC) electronic ballasts are proposed in this paper. The CPPFC circuit and unity power factor condition using the charge pump concept are derived and analyzed. The average lamp current control with switching frequency modulation was developed so that the low crest factor and constant lamp power operation can be achieved. The developed electronic ballast has continuous input current, so that a small line input filter can be used. The proposed CIC-CPPFC electronic ballast was implemented and tested with two 45-W fluorescent lamps. It is shown that the measured line input current harmonics satisfy IEC 1000-3-2 Class C requirements.

Qian, J.; Lee, F.C. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States); Yamauchi, Tokushi [Matsushita Electric Works, Ltd., Osaka (Japan). Lighting Research and Development Center

1999-03-01

172

A method to correct satellite measurements of sea surface temperature for the effects of atmospheric aerosols  

NASA Astrophysics Data System (ADS)

Multichannel sea surface temperature (MCSST) measurements with the NOAA 7 advanced very high resolution radiometer (AVHRR) have been corrected for the effects of the El Chichon aerosol layer by using a previously developed method of inferring the aerosol optical thickness (?) from the channel 1 radiance. A theoretical model shows that the error in the MCSST is directly proportional to ? sec ?, where ? is the satellite zenith angle. Data using moored buoy SST's and AVHRR MCSST's at five locations verify this relationship. Analysis of the data also shows empirically that the MCSST error is more closely related to ln (? sec2?). Linear regressions for these relationships for the combined data of two locations show correlation coefficients of 0.80 and 0.88 for the ?sec ? and ln (? sec2?) relationships, respectively. These regression lines are used to correct the MCSST values in the independent data sets of the other three locations. Statistics of the comparison between the corrected MCSST's and the buoy SST's show that the root mean square difference in the MCSST and buoy SST comparison is 1.14C and 1.01C for the ?sec ? and ln (?sec2?) relationships, respectively. These values are close to the value of 1.05C found in an extensive study at NOAA of an earlier MCSST algorithm that was not influenced by aerosols. Before this correction, considerable daytime data were rejected by the MCSST algorithm, and errors as large as 7C were observed. It appears that the correction procedure can be used in the presence of partial cloud in a pixel, since both the MCSST and the aerosol algorithms interpret the partial cloud as a uniform haze. Thus the technique also results in the retrieval of more MCSST values (than are currently available with the NOAA cloud filter tests) in the presence of clouds in normal aerosol conditions. The technique also offers the potential of increasing the accuracy of MCSST measurements in normal atmospheres where the aerosols are mostly in the troposphere.

Griggs, M.

1985-12-01

173

The non-uniformity correction factor for the cylindrical ionization chambers in dosimetry of an HDR 192Ir brachytherapy source  

PubMed Central

The aim of this study is to derive the non-uniformity correction factor for the two therapy ionization chambers for the dose measurement near the brachytherapy source. The two ionization chambers of 0.6 cc and 0.1 cc volume were used. The measurement in air was performed for distances between 0.8 cm and 20 cm from the source in specially designed measurement jig. The non-uniformity correction factors were derived from the measured values. The experimentally derived factors were compared with the theoretically calculated non-uniformity correction factors and a close agreement was found between these two studies. The experimentally derived non-uniformity correction factor supports the anisotropic theory.

Majumdar, Bishnu; Patel, Narayan Prasad; Vijayan, V.

2006-01-01

174

Factor analysis for spillover correction or movement detection in dynamic PET studies  

NASA Astrophysics Data System (ADS)

In this study, we applied factor analysis of dynamic structures (FADS) techniques in dynamic PET images to (1) extract the arterial time activity curve (TAC) from human adult or small monkey dynamic FDG PET; and (2) investigate the use of FADS generated factor images and factor curves to detect large subject movements during dynamic GA-68 EDTA scans of brain tumor patients. The results showed that a blood sample constraint improved the accuracy of FADS technique in extracting the `pure' blood pool TAC from dynamic PET studies that have large spillover problems. The studies of GA-68 EDTA brain PET studies showed that three major factors were extracted from images using FADS. For studies with little patient movement, a standard pattern of three factor curves and three factor images were obtained. However, large patient movement changed the outcomes of FADS results. We conclude that (1) FADS technique with a blood sample allows the extraction of the `pure' blood pool TAC directly from quantitative PET images without requiring multiple blood samples, region-of- interest drawing or spillover correction; and (2) FADS technique provides a sensitive way to detect large patient movements in dynamic PET studies.

Wu, Han-Ming; Hoh, Carl K.; Huang, Sung-Cheng

1996-04-01

175

Reliability of IGBT in a STATCOM for Harmonic Compensation and Power Factor Correction  

SciTech Connect

With smart grid integration, there is a need to characterize reliability of a power system by including reliability of power semiconductors in grid related applications. In this paper, the reliability of IGBTs in a STATCOM application is presented for two different applications, power factor correction and harmonic elimination. The STATCOM model is developed in EMTP, and analytical equations for average conduction losses in an IGBT and a diode are derived and compared with experimental data. A commonly used reliability model is used to predict reliability of IGBT.

Gopi Reddy, Lakshmi Reddy [ORNL; Tolbert, Leon M [ORNL; Ozpineci, Burak [ORNL; Xu, Yan [ORNL; Rizy, D Tom [ORNL

2012-01-01

176

Perturbative pion-photon transition form factors with transverse momentum corrections  

NASA Astrophysics Data System (ADS)

We perform a perturbative QCD analysis of the quark transverse momentum effect on the pion-photon transition form factors F?? and F??* in the standard light-cone formalism, with two phenomenological models of the wave function as the input of the nonperturbative aspect of the pion. We point out that the transverse momentum dependence in both the numerator and the denominator of the hard scattering amplitude is of the same importance and should be considered consistently. It is shown that after taking into account the quark transverse momentum corrections, the results obtained from different model wave functions are consistent with the available experimental data at finite Q2.

Cao, Fu-Guang; Huang, Tao; Ma, Bo-Qiang

1996-06-01

177

Longitudinal measurement of chromatic dispersion along an optical fiber transmission system with a new correction factor  

NASA Astrophysics Data System (ADS)

At present existence OTDR based techniques have become a standard practice for measuring chromatic dispersion distribution along an optical fiber transmission link. A constructive measurement technique has been offered in this paper, in which a four wavelength bidirectional optical time domain reflectometer (OTDR) has been used to compute the chromatic dispersion allocation beside an optical fiber transmission system. To improve the correction factor a novel formulation has been developed, which leads to an enhanced and defined measurement. The investigational outcomes obtained are in good harmony.

Abbasi, Madiha; Imran Baig, Mirza; Shafique Shaikh, Muhammad

2013-12-01

178

Temperature, gravity, and bolometric correction scales for non-supergiant OB stars  

NASA Astrophysics Data System (ADS)

Context. Precise and accurate determinations of the atmospheric parameters effective temperature and surface gravity are mandatory to derive reliable chemical abundances in OB stars. Furthermore, fundamental parameters like distances, masses, radii, luminosities can also be derived from the temperature and gravity of the stars. Aims: Atmospheric parameters recently determined at high precision with several independent spectroscopic indicators in non-local thermodynamic equilibrium, with typical uncertainties of ~300 K for temperature and of ~0.05 dex for gravity, are employed to calibrate photometric relationships. This is in order to investigate whether a faster tool to estimate atmospheric parameters can be provided. Methods: Temperatures and gravities of 30 calibrators, i.e. well-studied OB main sequence to giant stars in the solar neighbourhood, are compared to reddening-independent quantities of the Johnson and Strmgren photometric systems, assuming normal reddening. In addition, we examine the spectral and luminosity classification of the star sample and compute bolometric corrections. Results: Calibrations of temperatures and gravities are proposed for various photometric indices and spectral types. Once the luminosity of the stars is well known, effective temperatures can be determined at a precision of ~400 K for luminosity classes III/IV and ~800 K for luminosity class V. Furthermore, surface gravities can reach internal uncertainties as low as ~0.08 dex when using our calibration to the Johnson Q-parameter. Similar precision is achieved for gravities derived from the ?-index and the precision is lower for both atmospheric parameters when using the Strmgren indices [c1] and [u - b] . In contrast, external uncertainties are larger for the Johnson than for the Strmgren calibrations. Our uncertainties are smaller than typical differences among other methods in the literature, reaching values up to 2000 K for temperature and 0.25 dex for gravity, and in extreme cases, + 6000 K and 0.4 dex, respectively. A parameter calibration for sub-spectral types is also proposed. Moreover, we present a new bolometric correction relation to temperature based on our empirical data, rather than on synthetic grids. Conclusions: The photometric calibrations presented here are useful tools to estimate effective temperatures and surface gravities of non-supergiant OB stars in a fast manner. This is also applicable to some single-line spectroscopic binaries, but caution has to be taken for undetected double-lined spectroscopic binaries and single objects with anomalous reddening-law, dubious photometric quantities and/or luminosity classes, for which the systematic uncertainties may increase significantly. We recommend to use these calibrations only as a first step of the parameter estimation, with subsequent refinements based on spectroscopy. A larger sample covering more uniformly the parameter space under consideration will allow refinements to the present calibrations. Based on observations collected at the Centro Astronmico Hispano Alemn (CAHA) at Calar Alto, operated jointly by the Max- Planck Institut fr Astronomie and the Instituto de Astrofsica de Andaluca (CSIC), proposals H2001-2.2-011 and H2005-2.2-016.Based on observations collected at the European Southern Observatory, Chile, ESO 074.B-0455(A) and from the ESO Archive.Based on spectral data retrieved from the ELODIE archive at Observatoire de Haute-Provence (OHP).Appendices A and B are available in electronic form at http://www.aanda.org

Nieva, M.-F.

2013-02-01

179

Hydrophone area-averaging correction factors in nonlinearly generated ultrasonic beams  

NASA Astrophysics Data System (ADS)

The nonlinear propagation of an ultrasonic wave can be used to produce a wavefield rich in higher frequency components that is ideally suited to the calibration, or inter-calibration, of hydrophones. These techniques usually use a tone-burst signal, limiting the measurements to harmonics of the fundamental calibration frequency. Alternatively, using a short pulse enables calibration at a continuous spectrum of frequencies. Such a technique is used at PTB in conjunction with an optical measurement technique to calibrate devices. Experimental findings indicate that the area-averaging correction factor for a hydrophone in such a field demonstrates a complex behaviour, most notably varying periodically between frequencies that are harmonics of the centre frequency of the original pulse and frequencies that lie midway between these harmonics. The beam characteristics of such nonlinearly generated fields have been investigated using a finite difference solution to the nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation for a focused field. The simulation results are used to calculate the hydrophone area-averaging correction factors for 0.2 mm and 0.5 mm devices. The results clearly demonstrate a number of significant features observed in the experimental investigations, including the variation with frequency, drive level and hydrophone element size. An explanation for these effects is also proposed.

Cooling, M. P.; Humphrey, V. F.; Wilkens, V.

2011-02-01

180

A posteriori estimates for shear correction factors in multilayered composite cylinders  

NASA Technical Reports Server (NTRS)

A predictor-corrector approach is presented for calculating the composite shear correction factors and analyzing multilayered composite cylinders. In the predictor phase a two-dimensional first-order shear deformation theory is used to predict the gross response characteristics of the cylinder (vibration frequencies, average through-the-thickness displacements, rotations, and transverse shear strain energy per unit area) as well as the in-plane strains and stresses in the thickness direction. The three-dimensional equilibrium equations and constitutive relations are then used to compute the transverse stresses and strains as well as the transverse shear factors, and they are also used to correct the predicted response quantities of the cylinder. For simply supported multilayered cylinders the response quantities obtained by using the proposed approach are shown to be in close agreement with three-dimensional elasticity solutions for a wide range of lamination and geometric parameters. Also, the potential of the proposed approach for use in conjunction with large-scale finite element models of composite cylinders is outlined.

Noor, Ahmed K.; Peters, Jeanne M.

1989-01-01

181

Application of geometry correction factors for low-level waste package dose measurements. Revision 1  

SciTech Connect

Plans are to determine the Cs-137 content of low-level waste packages generated in High-Level Waste by measuring the radiation level at a specified distance from the package with a hand-held radiation instrument. The measurement taken at this specified distance, either 3 or 5 feet, is called the far-field measurement. This report documents a method for adjusting the gamma exposure rate (mR/hr) reading used in dose-to-curie determinations when the far-field measurement equals the background reading. This adjustment is necessary to reduce the conservatism resulting from using a minimum detection limit exposure rate for the dose-to-curie determination for the far-field measurement position. To accomplish this adjustment, the near-field (5 cm) measurement is multiplied by a geometry correction factor to obtain an estimate of the far field exposure rate (which is below instrument sensitivity). This estimate of the far field exposure rate is used to estimate the Cs-137 curie content of the package. This report establishes the geometry correction factors for the dose-to-curie determination when the far-field gamma exposure measurement equals the background reading. This report also provides a means of demonstrating compliance to 1S Manual requirements for exposure rate readings at different locations from waste packages while specifying only two measurement positions. This demonstration of compliance is necessary to minimize the number of locations exposure rate measurements that are required, i.e., ALARA.

Chandler, M.C.; Parish, B.

1995-01-05

182

Home radon levels and seasonal correction factors for the Isle of Man  

NASA Astrophysics Data System (ADS)

Ionizing radiation dose levels due to home radon can rise to levels that would be illegal for workers in the nuclear industry. It is well known that radon levels within homes and from home to home, and also from month to month, vary considerably. To define an Isle of Man radon seasonal correction factor, readings were taken in eight homes over a 12 month period. An average island indoor exposure of 48 Bq m-3 (range 4-518 Bq m-3) was determined from 285 homes selected from a cohort of 1300 families participating in the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) in the Isle of Man. This compares with a UK home average of 20 Bq m-3 and a European Union average (excluding UK) of 68 Bq m-3. Ten homes of those measured were found to have radon levels above the National Radiological Protection Board 200 Bq m-3 action level. There are 29 377 homes on the Isle of Man, suggesting that there could be some 900 or more homes above the action level. No statistical difference was found between the NRPB and Isle of Man seasonal correction factors.

Grainger, P.; Shalla, S. H.; Preece, A. W.; Goodfellow, S. A.

2000-08-01

183

Aerosol Correction for Remotely Sensed Sea Surface Temperatures From the NOAA AVHRR: Phase II  

NASA Astrophysics Data System (ADS)

For over two decades, the National Oceanic and Atmospheric Administration (NOAA) has produced global retrievals of sea surface temperature (SST) using infrared (IR) data from the Advanced Very High Resolution Radiometer (AVHRR). The standard multichannel retrieval algorithms are derived from regression analyses of AVHRR window channel brightness temperatures against in situ buoy measurements under non-cloudy conditions thus providing a correction for IR attenuation due to molecular water vapor absorption. However, for atmospheric conditions with elevated aerosol levels (e.g., arising from dust, biomass burning and volcanic eruptions), such algorithms lead to significant negative biases in SST because of IR attenuation arising from aerosol absorption and scattering. This research presents the development of a 2nd-phase aerosol correction algorithm for daytime AVHRR SST. To accomplish this, a long-term (1990-1998), global AVHRR-buoy matchup database was created by merging the Pathfinder Atmospheres (PATMOS) and Oceans (PFMDB) data sets. The merged data are unique in that they include multi-year, global daytime estimates of aerosol optical depth (AOD) derived from AVHRR channels 1 and 2 (0.63 and 0.83 ? m, respectively), along with an effective Angstrom exponent derived from the AOD retrievals (Ignatov and Nalli, 2002). Recent enhancements in the aerosol data constitute an improvement over the Phase I algorithm (Nalli and Stowe, 2002) which relied only on channel 1 AOD and the ratio of normalized reflectance from channels 1 and 2. The Angstrom exponent and channel 2 AOD provide important statistical information about the particle size distribution of the aerosol. The SST bias can be parametrically expressed as a function of observed AVHRR channels 1 and 2 slant-path AOD, normalized reflectance ratio and the Angstrom exponent. Based upon these empirical relationships, aerosol correction equations are then derived for the daytime multichannel and nonlinear SST (MCSST and NLSST) algorithms. Separate sets of coefficients are utilized for two aerosol modes, these being stratospheric/tropospheric (e.g., volcanic aerosol) and tropospheric (e.g., dust, smoke). The algorithms are subsequently applied to retrospective PATMOS data to demonstrate the potential for climate applications. The minimization of cold biases in the AVHRR SST, as demonstrated in this work, should improve its overall utility for the general user community.

Nalli, N. R.; Ignatov, A.

2002-05-01

184

Experimental setup for the determination of the correction factors of the neutron doseratemeters in fast neutron fields  

NASA Astrophysics Data System (ADS)

The use of the U-120 Cyclotron of the IFIN-HH allowed to perform a testing bench with fast neutrons in order to determine the correction factors of the doseratemeters dedicated to neutron measurement. This paper deals with researchers performed in order to develop the irradiation facility testing the fast neutrons flux generated at the Cyclotron. This facility is presented, together with the results obtain in determining the correction factor for a doseratemeter dedicated to the neutron dose equivalent rate measurement.

Iliescu, Elena; Bercea, Sorin; Dudu, Dorin; Celarel, Aurelia

2013-12-01

185

Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation.  

PubMed

The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. ["Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects," Mol. Phys. 110, 1069-1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effects of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations. PMID:24852552

Collell, Julien; Galliero, Guillaume

2014-05-21

186

Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation  

NASA Astrophysics Data System (ADS)

The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. ["Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects," Mol. Phys. 110, 1069-1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effects of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations.

Collell, Julien; Galliero, Guillaume

2014-05-01

187

Correction factors for the INER-improved free-air ionization chambers calculated with the Monte Carlo method.  

PubMed

Monte Carlo method was used to simulate the correction factors for electron loss and scattered photons for two improved cylindrical free-air ionization chambers (FACs) constructed at the Institute of Nuclear Energy Research (INER, Taiwan). The method is based on weighting correction factors for mono-energetic photons with X-ray spectra. The newly obtained correction factors for the medium-energy free-air chamber were compared with the current values, which were based on a least-squares fit to experimental data published in the NBS Handbook 64 [Wyckoff, H.O., Attix, F.H., 1969. Design of free-air ionization chambers. National Bureau Standards Handbook, No. 64. US Government Printing Office, Washington, DC, pp. 1-16; Chen, W.L., Su, S.H., Su, L.L., Hwang, W.S., 1999. Improved free-air ionization chamber for the measurement of X-rays. Metrologia 36, 19-24]. The comparison results showed the agreement between the Monte Carlo method and experimental data is within 0.22%. In addition, mono-energetic correction factors for the low-energy free-air chamber were calculated. Average correction factors were then derived for measured and theoretical X-ray spectra at 30-50 kVp. Although the measured and calculated spectra differ slightly, the resulting differences in the derived correction factors are less than 0.02%. PMID:16427292

Lin, Uei-Tyng; Chu, Chien-Hau

2006-05-01

188

Sea surface temperature estimation from the DMSP operational linescan system using a SSM/I-derived water vapor correction  

SciTech Connect

Atmospheric correction algorithms for Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) single channel infrared (IR) estimation of sea surface temperature (SST) have been derived based on Special Sensor Microwave/Imager (SSM/I) water vapor (WV) content retrievals. It is demonstrated that the OLS single IR channel atmospheric correction can be correlated to WV and that the SSM/I-derived correction algorithms provide significant improvement over uncorrected single IR channel SST estimation. Best results are obtained from a correction algorithm that incorporates a quadratic WV term. Use of the quadratic SSM/I-derived WV correction on properly cloud screened OLS IR data produces SST retrievals accurate to within 1.0[degree]C RMS when compared to moored buoy in situ SST measurements. 12 refs., 4 figs., 3 tabs.

May, D.A. (Naval Research Lab., Stennis Space Center, MS (United States))

1993-04-09

189

Artificial neural network based microwave precipitation estimation using scattering index and polarization corrected temperature  

NASA Astrophysics Data System (ADS)

An Artificial Neural Network (ANN) based technique is proposed for estimating precipitation over Indian land and oceanic regions [30 S - 40 N and 30 E - 120 E] using Scattering Index (SI) and Polarization Corrected Temperature (PCT) derived from Special Sensor Microwave Imager (SSM/I) measurements. This rainfall retrieval algorithm is designed to estimate rainfall using a combination of SSM/I and Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) measurements. For training the ANN, SI and PCT (which signify rain signatures in a better way) calculated from SSM/I brightness temperature are considered as inputs and Precipitation Radar (PR) rain rate as output. SI is computed using 19.35 GHz, 22.235 GHz and 85.5 GHz Vertical channels and PCT is computed using 85.5 GHz Vertical and Horizontal channels. Once the training is completed, the independent data sets (which were not included in the training) were used to test the performance of the network. Instantaneous precipitation estimates with independent test data sets are validated with PR surface rain rate measurements. The results are compared with precipitation estimated using power law based (i) global algorithm and (ii) regional algorithm. Overall results show that ANN based present algorithm shows better agreement with PR rain rate. This study is aimed at developing a more accurate operational rainfall retrieval algorithm for Indo-French Megha-Tropiques Microwave Analysis and Detection of Rain and Atmospheric Structures (MADRAS) radiometer.

Mahesh, C.; Prakash, Satya; Sathiyamoorthy, V.; Gairola, R. M.

2011-11-01

190

Factors Affecting Clinical Results after Corrective Osteotomy for Lumbar Degenerative Kyphosis  

PubMed Central

Study Design This study is a prospective, clinical study for lumbar degenerative kyphosis. Purpose To determine the factors affecting postoperative clinical outcomes in patients who undergo corrective osteotomy for lumbar degenerative kyphosis. Overview of Literature Only a small number of studies have reported clinical results for surgery for lumbar degenerative kyphosis. There are almost no studies about prognostic factors that predict postoperative clinical results. Methods This study involved 25 patients who were diagnosed with lumbar degenerative kyphosis and who underwent corrective osteotomy following gait analysis. A pedicle subtraction osteotomy was done at the third lumbar vertebra (L 3). Regarding the fusion level, surgery was done within a range from T10 proximally to S1 distally. Of these, for rigid fixation of a distal part, an iliac screw was used. Pain was evaluated using a 10-point pain scale and a questionnaire about activities. We also evaluated cosmesis and subjective satisfaction using a modified version of the Scoliosis Research Society Outcome-22 (SRS-22) instrument. This assessment was done using a 5-point scale which was designed by us. We assigned patients to group A (good clinical outcomes) if their postoperative pain score was lower than 4 (of 10 points) and if scores indicating activity, cosmesis and subjective satisfaction were higher than 11 (of 15 points). All other patients were assigned to group B (poor clinical outcomes). Results Clinical outcomes were good in 64% of patients (16/25) and poor in 36% (9/25). Regarding cosmesis and subjective satisfaction, there were significant differences between the two groups. There were also significant differences in physical factors of individual patients such as body mass index (BMI): 23.78 2.79 in group A and 26.44 2.75 in group B. On gait analysis, there was a significant difference in the dynamic pelvic tilt: 7.5 3.3 in group A and 11.72 1.89 in group B. Conclusions There is no correlation between preoperative degree of kyphotic deformity and clinical outcomes. The degree of anterior rotation of pelvic tilt does not change significantly; rather, compensatory mechanisms of the pelvis and BMI were found to have more influence. Because neither the degree of satisfaction with clinical outcomes nor the increased activity was relatively higher, a more sincere decision should be made before recommending corrective osteotomy for degenerative lumbar kyphosis.

Kim, Whoan Jeang; Kang, Sung Il; Sung, Hwan Il; Park, Kun Young; Park, Jae Guk; Kwon, Won Cho; Choy, Won Sik

2010-01-01

191

A novel correction factor based on extended volume to complement the conformity index  

PubMed Central

Objective We propose a modified conformity index (MCI), based on extended volume, that improves on existing indices by correcting for the insensitivity of previous conformity indices to reference dose shape to assess the quality of high-precision radiation therapy and present an evaluation of its application. Methods In this paper, the MCI is similar to the conformity index suggested by Paddick (CIPaddick), but with a different correction factor. It is shown for three cases: with an extended target volume, with an extended reference dose volume and without an extended volume. Extended volume is generated by expanding the original volume by 0.11.1 cm isotropically. Focusing on the simulation model, measurements of MCI employ a sphere target and three types of reference doses: a sphere, an ellipsoid and a cube. We can constrain the potential advantage of the new index by comparing MCI with CIPaddick. The measurements of MCI in headneck cancers treated with intensity-modulated radiation therapy and volumetric-modulated arc therapy provide a window on its clinical practice. Results The results of MCI for a simulation model and clinical practice are presented and the measurements are corrected for limited spatial resolution. The three types of MCI agree with each other, and comparisons between the MCI and CIPaddick are also provided. Conclusion The results from our analysis show that the proposed MCI can provide more objective and accurate conformity measurement for high-precision radiation therapy. In combination with a dosevolume histogram, it will be a more useful conformity index.

Jin, F; Wang, Y; Wu, Y-Z

2012-01-01

192

Seroprevalence and Risk Factors of Hepatitis C Virus among Juveniles in Correctional Center in Isfahan, Iran  

PubMed Central

Objectives: Juveniles in custody are affected by blood borne viruses due to high rates of risk behaviors. Therefore, they have a disproportionate burden of infectious diseases, such as hepatitis C virus (HCV) infection. The purpose of the present study was to determine prevalence and associated characteristics of hepatitis C infection in inmates of a correctional center in Isfahan, Iran. Methods: We conducted a cross-sectional study of HCV infection in 160 youths, who were admitted to correctional center in Isfahan during 2008-2009. Subjects were asked questions regarding behaviors that might put them at high risk for acquiring HCV and blood was drawn for this test. Sera were analyzed for HCV Ab and RIBA test was performed on antibody-positive HCV. We used Chi-square test and logistic regression model to analyze data and P < 0.05 was considered statistically significant. Results: A total of 160 young prisoners (147 boys and 13 girls) were studied. The mean age of the inmates was 16.59 1.24 year. A history of intravenous drug addiction was reported in 3.8% of them. HCV infection was detected in 7 (4.4%) subjects. This study revealed that history of IDU was the main risk factor for HCV (OR, 134.44; 95% confidence interval [CI], 7.29-2481.03). Conclusions: To prevent HCV transmission, proper drug prevention educations should be performed in young age prisoners.

Nokhodian, Zary; Ataei, Behrooz; Kassaian, Nazila; Yaran, Majid; Hassannejad, Razieh; Adibi, Peyman

2012-01-01

193

Coulomb corrections to the extraction of the density and temperature in non-relativistic heavy ion collisions  

NASA Astrophysics Data System (ADS)

We address the role of Coulomb interaction in the determination of densities and temperatures of hot sources produced in heavy ion collisions. Such quantities can be obtained from the quadrupole momentum and multiplicity fluctuations of the emitted light particles. In this paper we modify the method by taking explicitly into account Coulomb corrections. The classical and quantum limits for fermions are discussed. In the classical case we find that the temperatures determined from 3H and 3He, after the Coulomb correction, are very similar to those obtained from neutrons within the constrained molecular dynamics approach. In the quantum case, the proton temperature becomes very similar to neutrons, while densities are not sensitive to the Coulomb corrections.

Zheng, Hua; Giuliani, Gianluca; Bonasera, Aldo

2014-05-01

194

QCD corrections of all structure functions in transverse momentum dependent factorization for Drell-Yan processes  

NASA Astrophysics Data System (ADS)

We study the one-loop correction in Transverse-Momentum-Dependent(TMD) factorization for Drell-Yan processes at small transverse momentum of the lepton pair. We adopt the so-called subtractive approach, in which one can systematically construct contributions for subtracting long-distance effects represented by diagrams. The perturbative parts are obtained after the subtraction. We find that the perturbative coefficients of all structure functions in TMD factorization at leading twist are the same. The perturbative parts can also be studied with scattering of partons instead of hadrons. In this way, the factorization of many structure functions can only be examined by studying the scattering of multi-parton states, where there are many diagrams. These diagrams have no similarities to those treated in the subtractive approach. As an example, we use existing results of one structure function responsible for Single-Spin-Asymmetry, to show that these diagrams in the scattering of multi-parton states are equivalent to those treated in the subtractive approach after using Ward identity.

Ma, J. P.; Zhang, G. P.

2014-02-01

195

Free oscillation rheometry monitoring of haemodilution and hypothermia and correction with fibrinogen and factor XIII concentrates  

PubMed Central

Background Haemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry FOR (Reorox) is a novel viscoelastic haemostatic assay that has not been studied in this context before. Methods Blood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringers acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33C and 37C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor. Results Hydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringers acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringers acetate solution. Hypothermia did not influence any of the coagulation factor effects. Conclusions Both haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringers acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl starch induced clot instability, but improved coagulation in blood diluted with Ringers acetate solution. Fibrinogen improved coagulation irrespective of hypothermia.

2013-01-01

196

Control of power factor correcting boost converter without instantaneous measurement of input current  

SciTech Connect

This paper proposes a new control method for the constant-frequency control of power factor correcting boost converter using a sinewave template modulated PWM signal which eliminates the need for instantaneous measurement of the line current for the switching control of the boost converter. The control strategy is based on the notion that the line current can be forced to trace a deterministic waveform such as a sinusoid by considering the implicit model of the sinewave in the boost converter controller structure. The modulating sinewave template is generated using the line voltage, the boost converter output voltage and the load current. The paper provides the analysis and the design of the controller and presents simulation and implementation results to demonstrate its effectiveness.

Sivakumar, S.; Gudelewicz, R. [KB Electronics Ltd., Bedford, Nova Scotia (Canada)] [KB Electronics Ltd., Bedford, Nova Scotia (Canada); Natarajan, K. [Lakehead Univ., Thunder Bay, Ontario (Canada). Dept. of Electrical Engineering] [Lakehead Univ., Thunder Bay, Ontario (Canada). Dept. of Electrical Engineering

1995-07-01

197

Monte Carlo calculations of correction factors for plane-parallel ionization chambers in clinical electron dosimetry  

SciTech Connect

Recent standard dosimetry protocols recommend that plane-parallel ionization chambers be used in the measurements of depth-dose distributions or the calibration of low-energy electron beams with beam quality R{sub 50}<4 g/cm{sup 2}. In electron dosimetry protocols with the plane-parallel chambers, the wall correction factor, P{sub wall}, in water is assumed to be unity and the replacement correction factor, P{sub repl}, is taken to be unity for well-guarded plane-parallel chambers, at all measurement depths. This study calculated P{sub wall} and P{sub repl} for NACP-02, Markus, and Roos plane-parallel chambers in clinical electron dosimetry using the EGSnrc Monte Carlo code system. The P{sub wall} values for the plane-parallel chambers increased rapidly as a function of depth in water, especially at lower energy. The value around R{sub 50} for NACP-02 was about 10% greater than unity at 4 MeV. The effect was smaller for higher electron energies. Similarly, P{sub repl} values with depth increased drastically at the region with the steep dose gradient for lower energy. For Markus P{sub repl} departed more than 10% from unity close to R{sub 50} due to the narrow guard ring width. P{sub repl} for NACP-02 and Roos was close to unity in the plateau region of depth-dose curves that includes a reference depth, d{sub ref}. It was also found that the ratio of the dose to water and the dose to the sensitive volume in the air cavity for the plane-parallel chambers, D{sub w}/[D{sub air}]{sub pp}, at d{sub ref} differs significantly from that assumed by electron dosimetry protocols.

Araki, Fujio [Department of Radiological Technology, Kumamoto University School of Health Sciences, 4-24-1, Kuhonji, Kumamoto, 862-0976 (Japan)

2008-09-15

198

Error Detection, Factorization and Correction for Multi-View Scene Reconstruction from Aerial Imagery  

SciTech Connect

Scene reconstruction from video sequences has become a prominent computer vision research area in recent years, due to its large number of applications in fields such as security, robotics and virtual reality. Despite recent progress in this field, there are still a number of issues that manifest as incomplete, incorrect or computationally-expensive reconstructions. The engine behind achieving reconstruction is the matching of features between images, where common conditions such as occlusions, lighting changes and texture-less regions can all affect matching accuracy. Subsequent processes that rely on matching accuracy, such as camera parameter estimation, structure computation and non-linear parameter optimization, are also vulnerable to additional sources of error, such as degeneracies and mathematical instability. Detection and correction of errors, along with robustness in parameter solvers, are a must in order to achieve a very accurate final scene reconstruction. However, error detection is in general difficult due to the lack of ground-truth information about the given scene, such as the absolute position of scene points or GPS/IMU coordinates for the camera(s) viewing the scene. In this dissertation, methods are presented for the detection, factorization and correction of error sources present in all stages of a scene reconstruction pipeline from video, in the absence of ground-truth knowledge. Two main applications are discussed. The first set of algorithms derive total structural error measurements after an initial scene structure computation and factorize errors into those related to the underlying feature matching process and those related to camera parameter estimation. A brute-force local correction of inaccurate feature matches is presented, as well as an improved conditioning scheme for non-linear parameter optimization which applies weights on input parameters in proportion to estimated camera parameter errors. Another application is in reconstruction pre-processing, where an algorithm detects and discards frames that would lead to inaccurate feature matching, camera pose estimation degeneracies or mathematical instability in structure computation based on a residual error comparison between two different match motion models. The presented algorithms were designed for aerial video but have been proven to work across different scene types and camera motions, and for both real and synthetic scenes.

Hess-Flores, M

2011-11-10

199

Replacement correction factors for plane-parallel ion chambers in electron beams  

SciTech Connect

Purpose: Plane-parallel chambers are recommended by dosimetry protocols for measurements in (especially low-energy) electron beams. In dosimetry protocols, the replacement correction factor P{sub repl} is assumed unity for ''well-guarded'' plane-parallel chambers in electron beams when the front face of the cavity is the effective point of measurement. There is experimental evidence that ion chambers which are not well-guarded (e.g., Markus) have nonunity P{sub repl} values. Monte Carlo simulations are employed in this study to investigate the replacement correction factors for plane-parallel chambers in electron beams. Methods: Using previously established Monte Carlo calculation methods, the values of P{sub repl} are calculated with high statistical precision for the cavities of a variety of plane-parallel chambers in a water phantom irradiated by various electron beams. The dependences of the values of P{sub repl} on the beam quality, phantom depth, as well as the guard ring width are studied. Results: In the dose fall-off region for low-energy beams, the P{sub repl} values are very sensitive to depth. It is found that this is mainly due to the gradient effect, which originates from the fact that the effective point of measurement for many plane-parallel chambers should not be at the front face of the cavity but rather shifted toward the center of the cavity by a fraction of a millimeter. Using the front face of the cavity as the effective point of measurement, the calculated values of P{sub repl} at d{sub ref} are not unity for some well-guarded plane-parallel chambers. The calculated P{sub repl} values for the Roos chamber are close to 1 for all electron beams. The calculation results for the Markus chamber are in good agreement with the measured values. Conclusions: The appropriate selection of the effective point of measurement for plane-parallel chambers in electron beams is an important issue. If the effective point of measurement is correctly accounted for, the P{sub repl} values would be almost independent of depth. Both the guard ring width and the ratio of the collecting volume diameter to the cavity thickness can influence the values of P{sub repl}. For a diameter to thickness ratio of 5 (e.g., NACP02 chamber), the guard width has to be 6 mm for the chamber to be considered as well-guarded, i.e., have a P{sub repl} value of 1.00.

Wang, Lilie L. W.; Rogers, David W. O. [Ottawa Carleton Institute of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada)

2010-02-15

200

New acceleration factors for temperature, humidity, bias testing  

Microsoft Academic Search

New temperature-humidity acceleration factors for surface conductance (G) were determined. These can be used to relate device life in a high-stress laboratory environment to device life in a normal-use environment. Analytical expressions for the acceleration factors were derived for both encapsulated and unencapsulated test specimens. Lower acceleration factors were predicted for specimens encapsulated with DC 3-6550 RTV silicone rubber than

N. L. Sbar; R. P. Kozakiewicz

1979-01-01

201

Finite temperature corrections and embedded strings in noncommutative geometry and the standard model with neutrino mixing  

NASA Astrophysics Data System (ADS)

The recent extension of the standard model to include massive neutrinos in the framework of noncommutative geometry and the spectral action principle involves new scalar fields and their interactions with the usual complex scalar doublet. After ensuring that they bring no unphysical consequences, we address the question of how these fields affect the physics predicted in the Weinberg-Salam theory, particularly in the context of the electroweak phase transition. Applying the Dolan-Jackiw procedure, we calculate the finite temperature corrections, and find that the phase transition is first order. The new scalar interactions significantly improve the stability of the electroweak Z string, through the ``bag'' phenomenon described by Vachaspati and Watkins [``Bound states can stabilize electroweak strings,'' Phys. Lett. B 318, 163-168 (1993)]. (Recently, cosmic strings have climbed back into interest due to a new evidence.) Sourced by static embedded strings, an internal space analogy of Cartan's torsion is drawn, and a possible Higgs-force-like ``gravitational'' effect of this nonpropagating torsion on the fermion masses is described. We also check that the field generating the Majorana mass for the ?R is nonzero in the physical vacuum.

Martins, R. A.

2007-08-01

202

Finite temperature corrections and embedded strings in noncommutative geometry and the standard model with neutrino mixing  

SciTech Connect

The recent extension of the standard model to include massive neutrinos in the framework of noncommutative geometry and the spectral action principle involves new scalar fields and their interactions with the usual complex scalar doublet. After ensuring that they bring no unphysical consequences, we address the question of how these fields affect the physics predicted in the Weinberg-Salam theory, particularly in the context of the electroweak phase transition. Applying the Dolan-Jackiw procedure, we calculate the finite temperature corrections, and find that the phase transition is first order. The new scalar interactions significantly improve the stability of the electroweak Z string, through the 'bag' phenomenon described by Vachaspati and Watkins ['Bound states can stabilize electroweak strings', Phys. Lett. B 318, 163-168 (1993)]. (Recently, cosmic strings have climbed back into interest due to a new evidence.) Sourced by static embedded strings, an internal space analogy of Cartan's torsion is drawn, and a possible Higgs-force-like 'gravitational' effect of this nonpropagating torsion on the fermion masses is described. We also check that the field generating the Majorana mass for the {nu}{sub R} is nonzero in the physical vacuum.

Martins, R. A. [Centro de Analise Matematica, Geometria e Sistemas Dinamicos, Departamento de Matematica, Instituto Superior Tecnico, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal)

2007-08-15

203

Image quality improvements of electronic portal imaging devices by multi-level gain calibration and temperature correction  

NASA Astrophysics Data System (ADS)

Amorphous silicon (aSi:H) flat panel detectors are prevalent in radiotherapy for megavoltage imaging tasks. Any clinical and dosimetrical application requires a well-defined dose response of the system to achieve meaningful results. Due to radiation damages, panels deteriorate and the linearity of pixel response to dose as well as the stability with regard to changing operating temperatures get worse with time. Using a single level gain correction can lead to an error of about 23% when irradiating a flood field image with 100 MU min-1 on an old detector. A multi-level gain (MLG) correction is introduced, emending the nonlinearities and subpanel-related artifacts caused by insufficient radiation hardness of amplifiers in the read-out electronics. With rising temperature, offset values typically increase (up to 300 gray values) while the response at higher dose values per frame remain constant for a majority of pixels. To account for temperature-related image artifacts, two additional temperature correction methods have been developed. MLG in combination with temperature corrections can re-establish the aSi:H image quality to the performance required by reliable medical verification tools. Furthermore, the life span and recalibration intervals of these costly devices can be prolonged decisively.

Huber, S.; Mooslechner, M.; Mitterlechner, B.; Weichenberger, H.; Serpa, M.; Sedlmayer, F.; Deutschmann, H.

2013-09-01

204

Image quality improvements of electronic portal imaging devices by multi-level gain calibration and temperature correction.  

PubMed

Amorphous silicon (aSi:H) flat panel detectors are prevalent in radiotherapy for megavoltage imaging tasks. Any clinical and dosimetrical application requires a well-defined dose response of the system to achieve meaningful results. Due to radiation damages, panels deteriorate and the linearity of pixel response to dose as well as the stability with regard to changing operating temperatures get worse with time. Using a single level gain correction can lead to an error of about 23% when irradiating a flood field image with 100 MU min(-1) on an old detector. A multi-level gain (MLG) correction is introduced, emending the nonlinearities and subpanel-related artifacts caused by insufficient radiation hardness of amplifiers in the read-out electronics. With rising temperature, offset values typically increase (up to 300 gray values) while the response at higher dose values per frame remain constant for a majority of pixels. To account for temperature-related image artifacts, two additional temperature correction methods have been developed. MLG in combination with temperature corrections can re-establish the aSi:H image quality to the performance required by reliable medical verification tools. Furthermore, the life span and recalibration intervals of these costly devices can be prolonged decisively. PMID:23999060

Huber, S; Mooslechner, M; Mitterlechner, B; Weichenberger, H; Serpa, M; Sedlmayer, F; Deutschmann, H

2013-09-21

205

Region of validity of the finite-temperature Thomas-Fermi model with respect to quantum and exchange corrections  

NASA Astrophysics Data System (ADS)

We determine the region of applicability of the finite-temperature Thomas-Fermi model and its thermal part with respect to quantum and exchange corrections. Very high accuracy of computations has been achieved by using a special approach for the solution of the boundary problem and numerical integration. We show that the thermal part of the model can be applied at lower temperatures than the full model. Also we offer simple approximations of the boundaries of validity for practical applications.

Dyachkov, Sergey; Levashov, Pavel

2014-05-01

206

Enhanced conduction-corrected modified effective temperature as the outdoor thermal environment evaluation index upon the human body  

Microsoft Academic Search

This paper aims to clarify the handling technique of the solar radiation in an element of the thermal environment evaluation indices and to add expansions and improvements to conduction-corrected modified effective temperature ETF (Kurazumi etal., 2009) that can quantify the comprehensive effect on sensational and physiological sense and the effect of individual meteorological elements on the same evaluation axis applicable

Yoshihito Kurazumi; Kenta Fukagawa; Yoshiaki Yamato; Kunihito Tobita; Emi Kondo; Tadahiro Tsuchikawa; Tetsumi Horikoshi; Naoki Matsubara

2011-01-01

207

Quantum-Shell Corrections to the Finite-Temperature Thomas-Fermi-Dirac Statistical Model of the Atom.  

National Technical Information Service (NTIS)

Quantum-shell corrections are made directly to the finite-temperature Thomas-Fermi-Dirac statistical model of the atom by a partition of the electronic density into bound and free components. The bound component is calculated using analytic basis function...

2003-01-01

208

Determination of ?Pu airborne concentration alpha correction factor for a zinc sulfide detector via ambient Rn progeny air sampling.  

PubMed

This research empirically determined the ?Pu airborne concentration alpha correction factor for an ADM-300 zinc sulfide detection system via ambient Rn progeny air sampling using a RADeCO high volume air sampler. Radon progeny air samples were collected on a four inch glass fiber filter and evaluated on both a high purity germanium detector and the ADM?-300 simultaneously using the three count method. These data were analyzed to obtain a loss fraction in the glass fiber filter for the ?Bi collected. The ?Bi response then was used to estimate a loss fraction for ?Pu. The ?Pu airborne concentration alpha correction factor for the ADM-300 detection system was found to be 445 47 dpm ft cpm? m? as compared to a previously published correction factor of 500 dpm ft cpm? m?. PMID:21399436

Hale, Alan C; Tries, Mark A

2011-02-01

209

CORRIGENDUM: Diaphragm correction factors for free-air chamber standards for air kerma in x-rays Diaphragm correction factors for free-air chamber standards for air kerma in x-rays  

NASA Astrophysics Data System (ADS)

The paper describes the Monte Carlo calculation of diaphragm correction factors for free-air ionization chamber standards. Although not submitted for publication until December 2008, this work was carried out in 2006 and preliminary results were presented at the World Congress on Medical Physics and Biomedical Engineering of that year (Kessler 2006). Subsequently, Mainegra-Hing et al (2008) published the results of similar calculations for their own standard. In retrospect, the authors regret that they did not take the opportunity to revise their manuscript to include a citation to the work of Mainegra-Hing et al. The following sentence should be added at the end of the second paragraph of section 7 (Discussion) on page 2744 (following the text '...correction for diaphragm scatter.'): 'In a more recent work, Mainegra-Hing et al (2008) calculated a combined correction for diaphragm transmission and scatter of 0.9984 for their 250 kV measurement conditions. This is in agreement with the value 0.9983(3) obtained in the present work.' References Kessler C 2006 Calculation of the aperture scatter and transmission correction factors for the BIPM free-air chamber standards using the code PENELOPE World Congress on Medical Physics and Biomedical Engineering (27 August-1 September 2006, Seoul, Korea) Mainegra-Hing E, Reynaert N and Kawrakow I 2008 Novel approach for the Monte Carlo calculation of free-air chamber correction factors Med. Phys. 35 3650-60

Burns, D. T.; Kessler, C.

2009-07-01

210

Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations.  

PubMed

The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues. PMID:23629423

Palmans, H; Al-Sulaiti, L; Andreo, P; Shipley, D; Lhr, A; Bassler, N; Martinkovi?, J; Dobrovodsk, J; Rossomme, S; Thomas, R A S; Kacperek, A

2013-05-21

211

Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, kfl, is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by kfl = 0.9964 + 0.0024???zw-eq with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by kfl = 0.9947 + 0.0024???zw-eq with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues.

Palmans, H.; Al-Sulaiti, L.; Andreo, P.; Shipley, D.; Lhr, A.; Bassler, N.; Martinkovi?, J.; Dobrovodsk, J.; Rossomme, S.; Thomas, R. A. S.; Kacperek, A.

2013-05-01

212

Calibration of Gyros with Temperature Dependent Scale Factors  

NASA Technical Reports Server (NTRS)

The general problem of gyro calibration can be stated as the estimation of the scale factors, misalignments, and drift-rate biases of the gyro using the on-orbit sensor measurements. These gyro parameters have been traditionally treated as temperature-independent in the operational flight dynamics ground systems at NASA Goddard Space Flight Center (GSFC), a scenario which has been successfully applied in the gyro calibration of a large number of missions. A significant departure from this is the Microwave Anisotropy Probe (MAP) mission where, due to the high thermal variations expected during the mission phase, it is necessary to model the scale factors as functions of temperature. This paper addresses the issue of gyro calibration for the MAP gyro model using a manufacturer-supplied model of the variation of scale factors with temperature. The problem is formulated as a least squares problem and solved using the Levenberg-Marquardt algorithm in the MATLAB(R) library function NLSQ. The algorithm was tested on simulated data with Gaussian noise for the quaternions as well as the gyro rates and was found to consistently converge close to the true values. Significant improvement in accuracy was noticed due to the estimation of the temperature-dependent scale factors as against constant scale factors.

Belur, Sheela V.; Harman, Richard

2001-01-01

213

Myopia Stabilization and Associated Factors Among Participants in the Correction of Myopia Evaluation Trial (COMET)  

PubMed Central

Purpose. To use the Gompertz function to estimate the age and the amount of myopia at stabilization and to evaluate associated factors in the Correction of Myopia Evaluation Trial (COMET) cohort, a large ethnically diverse group of myopic children. Methods. The COMET enrolled 469 ethnically diverse children aged 6 to younger than 12 years with spherical equivalent refraction between ?1.25 and ?4.50 diopters (D). Noncycloplegic refraction was measured semiannually for 4 years and annually thereafter. Right eye data were fit to individual Gompertz functions in participants with at least 6 years of follow-up and at least seven refraction measurements over 11 years. Function parameters were estimated using a nonlinear least squares procedure. Associated factors were evaluated using linear regression. Results. In total, 426 participants (91%) had valid Gompertz curve fits. The mean (SD) age at myopia stabilization was 15.61 (4.17) years, and the mean (SD) amount of myopia at stabilization was ?4.87 (2.01) D. Ethnicity (P < 0.0001) but not sex or the number of myopic parents was associated with the age at stabilization. Ethnicity (P = 0.02) and the number of myopic parents (P = 0.01) but not sex were associated with myopia magnitude at stabilization. At stabilization, African Americans were youngest (mean age, 13.82 years) and had the least myopia (mean, ?4.36 D). Participants with two versus no myopic parents had approximately 1.00 D more myopia at stabilization. The age and the amount of myopia at stabilization were correlated (r = ?0.60, P < 0.0001). Conclusions. The Gompertz function provides estimates of the age and the amount of myopia at stabilization in an ethnically diverse cohort. These findings should provide guidance on the time course of myopia and on decisions regarding the type and timing of interventions.

2013-01-01

214

Investigation of systematic uncertainties in Monte Carlo-calculated beam quality correction factors.  

PubMed

Modern Monte Carlo codes allow for the calculation of ion chamber specific beam quality correction factors k(Q), which are needed for dosimetry in radiotherapy. While statistical (type A) uncertainties of the calculated data can be minimized sufficiently, the influence of systematic (type B) uncertainties is mostly unknown. This study presents an investigation of systematic uncertainties of Monte Carlo-based k(Q) values for a NE2571 thimble ion chamber, calculated with the EGSnrc system. Starting with some general investigation on transport parameter settings, the influence of geometry and source variations is studied. Furthermore, a systematic examination of uncertainties due to cross section is introduced by determining the sensitivity of k(Q) results to changes in cross section data. For this purpose, single components of the photon cross sections and the mean excitation energy I in the electron stopping powers are varied. The corresponding sensitivities are subsequently applied with information of standard uncertainties for the cross section data found in the literature. It turns out that the calculation of k(Q) factors with EGSnrc is mostly insensitive to transport settings within the statistical uncertainties of approximately 0.1%. Severe changes in the dimensions of the chamber lead to comparatively small, insignificant changes. Further, the inclusion of realistic beam models, delivering a complete phase space instead of simple photon spectra, does not significantly influence the result. However, the uncertainties in electron cross sections have an impact on the final uncertainty of k(Q) to a comparatively large degree. For the NE2571 chamber investigated in this work, this uncertainty amounts to 0.4% at 24 MV, decreasing to 0.2% at 6 MV. PMID:20668340

Wulff, J; Heverhagen, J T; Zink, K; Kawrakow, I

2010-08-21

215

Power factor correction system by means of continuous modulation. Final report  

SciTech Connect

The novel power factor correction system described here is an improvement over existing ones because it reduces the VAR`s with no switching transients, continuously; i.e., without the customary VAR-jumps that result from the usual capacitor-switchings. Work on this concept was begun in the early 1980`s by Mr. Frederick Rohatyn. The invention was granted a U.S. Patent (No. 4,672,298) in June 1987. Mr. Rohatyn continued his experiments for four year`s following issuance of the patent. During that time, he built several prototypes in order to develop a practical realization of his idea. The invention was evaluated technically by the U.S. Department of Commerce, National Institute of Standards and Technology (NIST), resulting in very favorable recommendations. In the invention, the compensating reactive power is generated by a linear capacitor. A transformer is connected in series with the capacitor. The voltage applied to the capacitor terminals can be varied from zero to a maximum level. This is done by supplying the primary winding of the series transformer from a variable auto-transformer. This feature permits continuous variation of the reactive power generated by the capacitor. Based on the results of this study, the industrial partner intends to develop a line of production models and market them to power management companies worldwide.

Zabar, Z.; Kaish, N.

1997-08-01

216

Power corrections to the ?0? transition form factor and pion distribution amplitudes  

NASA Astrophysics Data System (ADS)

Employing the standard hard-scattering approach and the running coupling method we calculate a class of power-suppressed corrections 1/Q2n, n=1,2,3, to the electromagnetic ?0? transition form factor (FF) Q2F??(Q2) arising from the end-point x?0,1 integration regions. In the investigation we use a hard-scattering amplitude of the subprocess ?+?*?q+q, symmetrized under the exchange ?2R??2R important for exclusive processes containing two external photons. In the computations the pion model distribution amplitudes (DAs) with one and two nonasymptotic terms are employed. The obtained predictions are compared with the CLEO data and constraints on the DA parameters b2(?20) and b4(?20) at the normalization point ?20=1 GeV2 are extracted. Further restrictions on the pion DAs are deduced from the experimental data on the electromagnetic FF F?(Q2).

Agaev, S. S.

2004-05-01

217

Differential dissolution of Lake Baikal diatoms: correction factors and implications for palaeoclimatic reconstruction  

NASA Astrophysics Data System (ADS)

In order to assess how faithfully the composition of diatom assemblages in the recent sediments of Lake Baikal represents the composition of the planktonic diatom populations in the lake, we have compared the flux of diatoms from the water column (i.e., "expected" in the sediment) with the accumulation rates of the same diatom taxa (i.e., "observed" in the sediment) from BAIK 38, a sediment core collected in the south basin of the lake. Whilst there are many uncertainties, the results indicate that only approximately 1% of the phytoplankton crop is preserved in the sediment and some species are more affected by dissolution than others. These findings are comparable to similar studies undertaken in the marine environment. In terms of differential dissolution, our studies suggest that the endemic taxa (e.g., Cyclotella minuta and Aulacoseira baicalensis) are the most resilient, whereas cosmopolitan taxa such as Nitzschia acicularis and Synedra acus are the least resilient. N. acicularis dissolves in the water column, but for other taxa, most dissolution takes place at the surface sediment-water interface. We use the data to develop a series of species-specific correction factors that allow the composition of the source populations to be reconstituted, and we argue that failure to take these processes into account can undermine the use of the diatom and biogenic silica record in Lake Baikal for palaeo-productivity and palaeoclimate reconstruction.

Battarbee, Richard W.; Mackay, A. W.; Jewson, D. H.; Ryves, D. B.; Sturm, M.

2005-04-01

218

Continuous correction of differential path length factor in near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p<0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p<0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method.

Talukdar, Tanveer; Moore, Jason H.; Diamond, Solomon G.

2013-05-01

219

Continuous correction of differential path length factor in near-infrared spectroscopy.  

PubMed

In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p < 0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15 Hz, 0.15 to 0.4 Hz and 0.4 to 2.0 Hz (p < 0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method. PMID:23640027

Talukdar, Tanveer; Moore, Jason H; Diamond, Solomon G

2013-05-01

220

Control of Dual-Opposed Stirling Convertors with Active Power Factor Correction Controllers  

NASA Technical Reports Server (NTRS)

When using recently-developed active power factor correction (APFC) controllers in power systems comprised of dual-opposed free-piston Stirling convertors, a variety of configurations of the convertors and controller(s) can be considered, with configuration ultimately selected based on benefits of efficiency, reliability, and robust operation. The configuration must not only achieve stable control of the two convertors, but also synchronize and regulate motion of the pistons to minimize net dynamic forces. The NASA Glenn Research Center (GRC) System Dynamic Model (SDM) was used to study ten configurations of dual-opposed convertor systems. These configurations considered one controller with the alternators connected in series or in parallel, and two controllers with the alternators not connected (isolated). For the configurations where the alternators were not connected, several different approaches were evaluated to synchronize the two convertors. In addition, two thermodynamic configurations were considered: two convertors with isolated working spaces and convertors with a shared expansion space. Of the ten configurations studied, stable operating modes were found for four. Three of those four had a common expansion space. One stable configuration was found for the dual-opposed convertors with separate working spaces. That configuration required isochronous control of both convertors, and two APFC controllers were used to accomplish this. A frequency/phase control loop was necessary to allow each APFC controller to synchronize its associated convertor with a common frequency.

Regan, Timothy F.; Lewandowski, Edward J.; Schreiber, Jeffrey G.

2006-01-01

221

Continuous correction of differential path length factor in near-infrared spectroscopy  

PubMed Central

Abstract. In continuous-wave near-infrared spectroscopy (CW-NIRS), changes in the concentration of oxyhemoglobin and deoxyhemoglobin can be calculated by solving a set of linear equations from the modified Beer-Lambert Law. Cross-talk error in the calculated hemodynamics can arise from inaccurate knowledge of the wavelength-dependent differential path length factor (DPF). We apply the extended Kalman filter (EKF) with a dynamical systems model to calculate relative concentration changes in oxy- and deoxyhemoglobin while simultaneously estimating relative changes in DPF. Results from simulated and experimental CW-NIRS data are compared with results from a weighted least squares (WLSQ) method. The EKF method was found to effectively correct for artificially introduced errors in DPF and to reduce the cross-talk error in simulation. With experimental CW-NIRS data, the hemodynamic estimates from EKF differ significantly from the WLSQ (p<0.001). The cross-correlations among residuals at different wavelengths were found to be significantly reduced by the EKF method compared to WLSQ in three physiologically relevant spectral bands 0.04 to 0.15Hz, 0.15 to 0.4Hz and 0.4 to 2.0Hz (p<0.001). This observed reduction in residual cross-correlation is consistent with reduced cross-talk error in the hemodynamic estimates from the proposed EKF method.

Talukdar, Tanveer; Moore, Jason H.; Diamond, Solomon G.

2013-01-01

222

Surface temperature-modulating factors in the Sonoran Desert, Mexico  

NASA Astrophysics Data System (ADS)

This study is focused on seasonal cycle of parameters, which modulate surface temperature in the Sonora desert (North-West Mexico). The understanding of this process is important for monitoring of desertification. In this paper, a new approach to the monitoring of desertification based on the use of the albedo mechanism is proposed. It is known that the positive albedo-precipitation feedback plays a significant role in the desertification process. The originality of the work rest on considering the albedo mechanism not in isolation but as a joint effect of two temperature-modulating factors: radiation and evapotranspiration. It is assumed that the prevalence of the radiation factor is a manifestation of the albedo mechanism. One indirect characteristic of prevalence of the radiation factor is Normalized Difference Vegetation Index (NDVI), which is an indicator of green phytomass. We define and substantiate the criterion of predominance of the radiation factor by using the threshold value of NDVI AVHRR. The area, within which the threshold value is achieved, is a key factor; the data on the variability of this area becomes useful and essential in the process of monitoring of desertification. This is true because in a certain year, the time span of the period, during which the radiation factor is predominant, is an important factor in the desertification process. The main features of the ratio between albedo and surface temperature are discussed in terms of analysis of monthly means (albedo, temperature, NDVI) in the state of Sonora (29-32N, 111-115W), in particular, within the box 30-31N, 112-113W.

Tereshchenko, I.; Zolotokryin, A.; Titkova, T.; Brito-Castillo, L.; Monzon, C.

2013-05-01

223

Correction analysis for a supersonic water cooled total temperature probe tested to 1370 K  

NASA Technical Reports Server (NTRS)

The authors address the thermal analysis of a water cooled supersonic total temperature probe tested in a Mach 2 flow, up to 1366 K total temperature. The goal of this experiment was the determination of high-temperature supersonic jet mean flow temperatures. An 8.99 cm exit diameter water cooled nozzle was used in the tests. It was designed for exit Mach 2 at 1366 K exit total temperature. Data along the jet centerline were obtained for total temperatures of 755 K, 1089 K, and 1366 K. The data from the total temperature probe were affected by the water coolant. The probe was tested through a range of temperatures between 755 K and 1366 K with and without the cooling system turned on. The results were used to develop a relationship between the indicated thermocouple bead temperature and the freestream total temperature. The analysis and calculated temperatures are presented.

Lagen, Nicholas T.; Seiner, John M.

1991-01-01

224

Subtherapeutic erythropoietin and insulin-like growth factor-1 correct the anemia of chronic renal failure in the mouse  

Microsoft Academic Search

Subtherapeutic erythropoietin and insulin-like growth factor-1 correct the anemia of chronic renal failure in the mouse. Chronic renal failure (CRF) is associated with a hyporegenerative anemia, which is caused primarily by inadequate production of erythropoietin (EPO) by the diseased kidneys and is responsive to exogenous EPO administration. Little is known about compensatory mechanisms that might supervene in anemia with low

Alan G Brox; Feng Zhang; Harvey Guyda; Raymonde F Gagnon

1996-01-01

225

Three dimensional model based on image theory for low frequency correction factors evaluation in semi-anechoic chambers  

Microsoft Academic Search

The need to study the radiated emissions from electric and electronic devices whose main energy content is below 50 MHz calls for the prediction of correction factors that allows one to correlate the direct electromagnetic field radiated by the device to the total measured field inside a test chamber due to the reflections on all the chamber's walls. A three-dimensional

G. Antonini; A. Orlandi

1997-01-01

226

A New Cycle by Cycle Controller for a Three Level Resonant Single Stage Power Factor Correction Converter  

Microsoft Academic Search

This paper presents a discrete time cycle by cycle controller for a three level resonant single stage power factor correction converter. The controller is supposed to generate variable frequency pulse width modulated (VFPWM) gate signals to the switches. The merits of such control method is to tightly regulate the output voltage, shape the input ac current as well as regulating

Mohammed S. Agamy; Praveen K. Jain

2006-01-01

227

Evaluation of off-axis wedge correction factor using diode dosimeters for estimation of delivered dose in external radiotherapy  

PubMed Central

An in vivo dosimetry system, using p-type diode dosimeters, was characterized for clinical applications of treatment machines ranging in megavoltage energies. This paper investigates two different models of diodes for externally wedged beams and explains a new algorithm for the calculation of the target dose at various tissue depths in external radiotherapy. The values of off-axis wedge correction factors were determined at two different positions in the wedged (toward the thick and thin edges) and in the non-wedged directions on entrance and exit surfaces of a polystyrene phantom in 60Co and 6 MV photon beams. Depth transmission was defined on the entrance and exit surfaces to obtain the off-axis wedge correction factor at any depth. As the sensitivity of the diodes depends on physical characteristics [field size, sourceskin distance (SSD), thickness, backscatter], correction factors were applied to the diode reading when measuring conditions different from calibration situations. The results indicate that needful correction factors for 60Co wedged photons are usually larger than those for 6 MV wedged photon beams. In vivo dosimetry performed with the proposed algorithms at externally wedged beams has negligible probable errors (less than 0.5&) and is a reliable method for patient dose control.

Allahverdi, Mahmoud; Mohammadkarim, Alireza; Esfehani, Mahbod; Nedaie, Hasanali; Shirazi, Alireza; Geraily, Ghazale

2012-01-01

228

Correction Factor for Determining the London Penetration Depth from Strip Resonators  

NASA Technical Reports Server (NTRS)

A significant disagreement is often seen between the theoretical temperature dependent magnetic penetration depth profile and experimentally derived calculations based on stripline type resonators. This short paper shows that the disagreement can be attributed to the susceptance coupled into the resonator from the gap discontinuity as well as the feed line. When the effect is taken into account, the natural resonant frequency of the resonator is increased, and the frequency shift due to kinetic inductance can be calculated much more accurately. While it is necessary to include this effect to determine the penetration depth, it is shown that the impact on unloaded quality factor is generally negligible. The situation when the strip characteristic impedance is not matched to the generator is included.

Romanofsky, Robert R.

1995-01-01

229

Calculation of the replacement correction factors for ion chambers in megavoltage beams by Monte Carlo simulation.  

PubMed

This article describes four methods of calculating the replacement correction factor, P(repl0 (or the product p(cav)P(dis) in the IAEA's notation), for a plane-parallel chamber in both electron and photon beams, and for a Farmer chamber in photon beams, by using the EGSnrc Monte Carlo code. The accuracy of underlying assumptions and relative merits of each technique are assessed. With careful selection of parameters it appears that all four methods give reasonable answers although the direct methods are more intellectually satisfying and more accurate in some cases. The direct methods are shown to have an accuracy of 0.11% when appropriate calculation parameters are selected. The depth dependence of P(repl) for the NACP02 plane-parallel chamber has been calculated in both 6 and 18 MeV electron beams. At the reference depth (0.6R50-0.1 cm) P(repl) is 0.9964 for the 6 MeV beam and 1.0005 for the 18 MeV beam for this well-guarded chamber; at the depth of maximum dose for the 18 MeV beam, P(repl) is 1.0010. P(repl) is also calculated for the NACP02 chamber and a Farmer chamber (diameter 6 mm) at a depth of 5 cm in a 60Co photon beam, giving values of 1.0063 and 0.9964, respectively. For the Farmer chamber, P(repl) is about half a percent higher than the value (0.992) recommended by the AAPM dosimetry protocol. It is found that the dosimetry protocols may have adopted an incorrect value of P(repl) for cylindrical chambers in photon beams. The nonunity values of P(repl) for plane-parallel chambers in lower energy electron beams imply a variety of values used in dosimetry protocols must be reassessed. PMID:18561649

Wang, L L W; Rogers, D W O

2008-05-01

230

Temperature can interact with landscape factors to affect songbird productivity.  

PubMed

Increased temperatures and more extreme weather patterns associated with global climate change can interact with other factors that regulate animal populations, but many climate change studies do not incorporate other threats to wildlife in their analyses. We used 20 years of nest-monitoring data from study sites across a gradient of habitat fragmentation in Missouri, USA, to investigate the relative influence of weather variables (temperature and precipitation) and landscape factors (forest cover and edge density) on the number of young produced per nest attempt (i.e., productivity) for three species of songbirds. We detected a strong forest cover temperature interaction for the Acadian Flycatcher (Empidonax virescens) on productivity. Greater forest cover resulted in greater productivity because of reduced brood parasitism and increased nest survival, whereas greater temperatures reduced productivity in highly forested landscapes because of increased nest predation but had no effect in less forested landscapes. The Indigo Bunting (Passerina cyanea) exhibited a similar pattern, albeit with a marginal forest cover temperature interaction. By contrast, productivity of the Northern Cardinal (Cardinalis cardinalis) was not influenced by landscape effects or temperature. Our results highlight a potential difficulty of managing wildlife in response to global change such as habitat fragmentation and climate warming, as the habitat associated with the greatest productivity for flycatchers was also that most negatively influenced by high temperatures. The influence of high temperatures on nest predation (and therefore, nest predators) underscores the need to acknowledge the potential complexity of species' responses to climate change by incorporating a more thorough consideration of community ecology in the development of models of climate impacts on wildlife. PMID:23504884

Cox, W Andrew; Thompson, Frank R; Reidy, Jennifer L; Faaborg, John

2013-04-01

231

Quantum-Shell Corrections to the Finite-Temperature Thomas-Fermi-Dirac Statistical Model of the Atom  

Microsoft Academic Search

Quantum-shell corrections are made directly to the finite-temperature Thomas-Fermi-Dirac statistical model of the atom by a partition of the electronic density into bound and free components. The bound component is calculated using analytic basis functions whose parameters are chosen to minimize the energy. Poisson's equation is solved for the modified density, thereby avoiding the need to solve Schroedinger's equation for

Ritchie

2003-01-01

232

Correction of eddy covariance water vapor flux using additional measurements of temperature  

Microsoft Academic Search

Evaporation measurements using the eddy covariance technique tend to underestimate latent heat flux, partly due to the separation between the water vapor sensor and the sonic anemometer. Although correction equations have been proposed, they rely on empirical turbulence spectra and might not be easy to apply to some situations. In this paper we test the hypothesis that relative flux losses

F. J. Villalobos

1997-01-01

233

Fatigue Crack Growth Rate and Stress-Intensity Factor Corrections for Out-of-Plane Crack Growth  

NASA Technical Reports Server (NTRS)

Fatigue crack growth rate testing is performed by automated data collection systems that assume straight crack growth in the plane of symmetry and use standard polynomial solutions to compute crack length and stress-intensity factors from compliance or potential drop measurements. Visual measurements used to correct the collected data typically include only the horizontal crack length, which for cracks that propagate out-of-plane, under-estimates the crack growth rates and over-estimates the stress-intensity factors. The authors have devised an approach for correcting both the crack growth rates and stress-intensity factors based on two-dimensional mixed mode-I/II finite element analysis (FEA). The approach is used to correct out-of-plane data for 7050-T7451 and 2025-T6 aluminum alloys. Results indicate the correction process works well for high DeltaK levels but fails to capture the mixed-mode effects at DeltaK levels approaching threshold (da/dN approximately 10(exp -10) meter/cycle).

Forth, Scott C.; Herman, Dave J.; James, Mark A.

2003-01-01

234

Application of neural fuzzy network to pyrometer correction and temperature control in rapid thermal processing  

Microsoft Academic Search

Temperature measurement and control are two difficult problems in the rapid thermal processing (RTP) system. For many applications such as rapid thermal processing chemical vapor deposition (RTCVD) and rapid thermal oxidation (RTO), large changes in wafer emissivity can occur during film growing, leading to erroneous temperature measurements with a single wavelength pyrometer. The error in the inferred temperature will affect

Jiun-Hong Lai; Chin-Teng Lin

1999-01-01

235

Voluntary STD testing and treatment program at a metropolitan correctional facility: evaluation of test acceptability and associated risk factors.  

PubMed

Few studies have addressed challenges of diagnosis and treatment of sexually transmitted diseases (STDs) within correctional facilities. Initiatives that screen all inmates can be cost-prohibitive, while symptom-based screening undoubtedly fails to recognize significant numbers of asymptomatically infected persons. This study discusses a voluntary STD screening and treatment program developed at the Douglas County (Nebraska) Department of Corrections where student volunteers interviewed, screened, and educated 456 inmates. Inmate urine samples and interview responses about risk behaviors and motivators for participation in the screening program were analyzed. The results support the ongoing project method to screen and treat inmates in the community correctional facility. Risk factor analysis suggests that targeted testing and treatment efforts may have a role in providing cost-effective care for STD among the incarcerated population. PMID:24352406

Brown, Christopher K; Earley, Mary; Shaikh, Raees; Fickenscher, Jillian; Ott, Jessica; Person, Austin; Islam, K M Monirul; Simonsen, Kari; Sandkovsky, Uriel; Kaiser, Katherine Laux; Foxall, Mark; Margalit, Ruth

2014-01-01

236

Temperature dependent thermoelectric material power factor measurement system  

NASA Astrophysics Data System (ADS)

Thermoelectric materials can be used for cooling/heating applications, or converting waste heat into electricity. Novel thermoelectric materials have been discovered in recent years. Characterization of an electrical conductivity and thermopower of a sample from room temperature to >=900 K is often necessary for thermoelectric materials. This paper describes a system built for measurement of the power factor of thermoelectric materials from 300 to 1273 K. Characterization results of the system are also presented.

D'Angelo, Jonathan; Downey, Adam; Hogan, Timothy

2010-07-01

237

Temperature dependent thermoelectric material power factor measurement system.  

PubMed

Thermoelectric materials can be used for cooling/heating applications, or converting waste heat into electricity. Novel thermoelectric materials have been discovered in recent years. Characterization of an electrical conductivity and thermopower of a sample from room temperature to > or = 900 K is often necessary for thermoelectric materials. This paper describes a system built for measurement of the power factor of thermoelectric materials from 300 to 1273 K. Characterization results of the system are also presented. PMID:20687759

D'Angelo, Jonathan; Downey, Adam; Hogan, Timothy

2010-07-01

238

Reference dosimetry condition and beam quality correction factor for CyberKnife beam  

SciTech Connect

This article is intended to improve the certainty of the absorbed dose determination for reference dosimetry in CyberKnife beams. The CyberKnife beams do not satisfy some conditions of the standard reference dosimetry protocols because of its unique treatment head structure and beam collimating system. Under the present state of affairs, the reference dosimetry has not been performed under uniform conditions and the beam quality correction factor k{sub Q} for an ordinary 6 MV linear accelerator has been temporally substituted for the k{sub Q} of the CyberKnife in many sites. Therefore, the reference conditions and k{sub Q} as a function of the beam quality index in a new way are required. The dose flatness and the error of dosimeter reading caused by radiation fields and detector size were analyzed to determine the reference conditions. Owing to the absence of beam flattening filter, the dose flatness of the CyberKnife beam was inferior to that of an ordinary 6 MV linear accelerator. And if the absorbed dose is measured with an ionization chamber which has cavity length of 2.4, 1.0 and 0.7 cm in reference dosimetry, the dose at the beam axis for a field of 6.0 cm collimator was underestimated 1.5%, 0.4%, and 0.2% on a calculation. Therefore, the maximum field shaped with a 6.0 cm collimator and ionization chamber which has a cavity length of 1.0 cm or shorter were recommended as the conditions of reference dosimetry. Furthermore, to determine the k{sub Q} for the CyberKnife, the realistic energy spectrum of photons and electrons in water was simulated with the BEAMnrc. The absence of beam flattening filter also caused softer photon energy spectrum than that of an ordinary 6 MV linear accelerator. Consequently, the k{sub Q} for ionization chambers of a suitable size were determined and tabulated as a function of measurable beam quality indexes in the CyberKnife beam.

Kawachi, Toru; Saitoh, Hidetoshi; Inoue, Mitsuhiro; Katayose, Tetsurou; Myojoyama, Atsushi; Hatano, Kazuo [Tokyo Metropolitan University Graduate School of Human Health Sciences, Tokyo, Japan and Chiba Cancer Center, Chiba (Japan); Tokyo Metropolitan University Graduate School of Human Health Sciences, Tokyo (Japan); Yokahama CyberKnife Center, Yokohama (Japan); Tokyo Metropolitan University Graduate School of Human Health Sciences, Tokyo (Japan); Chiba Cancer Center, Chiba (Japan)

2008-10-15

239

Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars  

Microsoft Academic Search

Broad band colors and bolometric corrections in the Johnson-Cousins-Glass system (Bessell, 1990; Bessell & Brett, 1988) have been computed from synthetic spectra from new model atmospheres of Kurucz (1995a), Castelli (1997), Plez, Brett & Nordlund (1992), Plez (1995-97), and Brett (1995a,b). These atmospheres are representative of larger grids that are currently being completed. We discuss differences between the different grids

M. S. Bessell; F. Castelli; B. Plez

1998-01-01

240

Shutterless solution for simultaneous focal plane array temperature estimation and nonuniformity correction in uncooled long-wave infrared camera.  

PubMed

In uncooled long-wave infrared (LWIR) microbolometer imaging systems, temperature fluctuations of the focal plane array (FPA) result in thermal drift and spatial nonuniformity. In this paper, we present a novel approach based on single-image processing to simultaneously estimate temperature variances of FPAs and compensate the resulting temperature-dependent nonuniformity. Through well-controlled thermal calibrations, empirical behavioral models are derived to characterize the relationship between the responses of microbolometer and FPA temperature variations. Then, under the assumption that strong dependency exists between spatially adjacent pixels, we estimate the optimal FPA temperature so as to minimize the global intensity variance across the entire thermal infrared image. We make use of the estimated FPA temperature to infer an appropriate nonuniformity correction (NUC) profile. The performance and robustness of the proposed temperature-adaptive NUC method are evaluated on realistic IR images obtained by a 640 512 pixels uncooled LWIR microbolometer imaging system operating in a significantly changed temperature environment. PMID:24085086

Cao, Yanpeng; Tisse, Christel-Loic

2013-09-01

241

Physical parameters and correction factors for ionization chambers for absolute measurement of air kerma in ?³-ray fields  

NASA Astrophysics Data System (ADS)

Values of physical parameters and correction factors essential for the absolute measurement of air kerma in 137Cs and 60Co ?-ray fields were obtained using an EGS5 program for spherical, cylindrical and pancake ionization chambers. The mean mass collision stopping power ratio for graphite and air, was found to vary depending on the cutoff energy of electrons employed in calculation. The ratio between the energies deposited in cavity air due to Compton electrons emitted from the air and those from the graphite wall increases as the chamber size is increased. It also increases as the ?-ray energy is reduced and is equal to 0.09 for 137Cs ?-rays in a spherical ionization chamber of cavity diameter 12 cm. Correction factors for ?-ray attenuation in chamber walls and those for the contribution of scattered ?-rays to chamber responses were obtained separately. The wall correction factor, which is equal to the product of these two factors, is close to unity for pancake chambers.

Takata, N.; Kurosawa, T.; Begum, A.; Sugita, T.

2007-09-01

242

Temperature variation of the structure factor of liquid helium  

NASA Astrophysics Data System (ADS)

The temperature variation of the structure factor S( q) of liquid helium follows S(q) = h?2q 2{{1 + 2f(?)}}/{2}m? , where f(?) is the Bose distribution function of the quasiparticles of energy ?( q). For very low temperatures, the formula predicts that S( q) increases linearly with q starting from a constant, S(0) = {kT}/{mc 2}. This trend changes at temperatures higher than T I = {c h?}/{k}?24? 1, where ? 1 is the coefficient to q2 of the energy dispersion relation. Therefore, above around 2.78 K, a minimum of S( q) is expected. These theoretical predictions are in good agreement with the recent experimental data of Sears, Svensson, Woods and Martel based on neutron diffraction and of Hallock obtained by X-ray scattering.

Isihara, A.

1981-07-01

243

Model-based emissivity correction in pyrometer temperature control of rapid thermal processing systems  

Microsoft Academic Search

Single-wavelength pyrometers are most often used to infer wafer temperature in rapid-thermal-processing (RTP) systems. A constant wafer emissivity is assumed with a pyrometer, but a variation in the wafer's surface emissivity can result in an error in the inferred temperature which affects the temperature control of the RTP system. A time-dependent variation is evident in rapid thermal chemical vapor deposition

F. Y. Sorrell; R. S. Gyurcsik

1993-01-01

244

Analysis of biologically-derived small particles--searching for geometry correction factors using Monte Carlo simulation.  

PubMed

A Monte Carlo simulation was used to determine geometry correction factors that increase accuracy of quantitative X-ray microanalysis of laterally semithick biological materials. A model composed of cellulose with homogeneously distributed biological elements and lateral dimensions between 0.5-25 ?m was chosen. The specimen was exposed to 5, 10, and 15 keV electrons, the net intensities of characteristic X-rays registered for the elements, and presented as a function of the lateral dimensions of the model. This showed the double decay exponential function fitted the distribution of X-ray intensities in relation to the model size. The applicability of the function as a correction method was successfully tested for 30 specimens with varying composition and dimensions. The value of relative error decreased from 60% to 5% when the correction was applied. Moreover, the minimal lateral size of the material was defined, below which the correction is not required. The simulation also revealed that the difference of the weighted sum of Z/A between the unknown and the standard could reach 25% without significant influence on the quantitative results. The correction method could be helpful for accurate assessment of elemental composition in biological or organic matrices, when their lateral dimensions are smaller than the distribution range. PMID:23302468

Tylko, Grzegorz

2013-02-01

245

Finite temperature application of the corrected propagator method to reactive dynamics in a condensed-phase environment  

PubMed Central

The recently proposed mixed quantum-classical method is extended to applications at finite temperatures. The method is designed to treat complex systems consisting of a low-dimensional quantum part (the primary system) coupled to a dissipative bath described classically. The method is based on a formalism showing how to systematically correct the approximate zeroth-order evolution rule. The corrections are defined in terms of the total quantum Hamiltonian and are taken to the classical limit by introducing the frozen Gaussian approximation for the bath degrees of freedom. The evolution of the primary system is governed by the corrected propagator yielding the exact quantum dynamics. The method has been tested on a standard model system describing proton transfer in a condensed-phase environment: a symmetric double-well potential bilinearly coupled to a bath of harmonic oscillators. Flux correlation functions and thermal rate constants have been calculated at two different temperatures for a range of coupling strengths. The results have been compared to the fully quantum simulations of Topaler and Makri [J. Chem. Phys. 101, 7500 (1994)] with the real path integral method.

Gelman, David; Schwartz, Steven D.

2011-01-01

246

Temperature dependence of the electron spin g factor in CdTe and InP  

NASA Astrophysics Data System (ADS)

Temperature dependence of the electron spin g factors in bulk CdTe and InP is calculated and compared with experiment. It is assumed that the only modification of the band structure related to temperature is a dilatation change in the fundamental energy gap. The dilatation changes of fundamental gaps are calculated for both materials using available experimental data. Computations of the band structures in the presence of a magnetic field are carried out employing five-level P.p model appropriate for medium-gap semiconductors. In particular, the model takes into account spin splitting due to bulk inversion asymmetry (BIA) of the materials. The resulting theoretical effective masses and g factors increase with electron energy due to band nonparabolicity. Average g values are calculated by summing over populated Landau and spin levels properly accounting for the thermal distribution of electrons in the band. It is shown that the spin splitting due to BIA in the presence of a magnetic field gives observable contributions to g values. Our calculations are in good agreement with experiments in the temperature range of 0 K to 300 K for CdTe and 0 K to 180 K for InP. The temperature dependence of g is stronger in CdTe than in InP due to different signs of band-edge g values in the two materials. Good agreement between the theory and experiments strongly indicates that the temperature dependence of spin g factors is correctly explained. In addition, we discuss formulas for the energy dependence of spin g factor due to band nonparabolicity, which are liable to misinterpretation.

Pfeffer, Pawel; Zawadzki, Wlodek

2012-04-01

247

Diurnal drift correction in the NESDIS\\/STAR MSU\\/AMSU atmospheric temperature climate data record  

Microsoft Academic Search

NESDIS\\/Center for Satellite Applications and Research (STAR) has been reprocessing and recalibrating observations from the Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) to generate atmospheric temperature climate data record (CDR). To obtain reliable atmospheric temperature trends from the dataset, diurnal drift errors due to orbital drift must be removed from the time series. This adjustment is especially

Cheng-Zhi Zou; Wenhui Wang

2009-01-01

248

Multispectral infrared pyrometer for temperature measurement with automatic correction of the influence of emissivity  

Microsoft Academic Search

A new method for contactless temperature measurement has been developed.(1) It is applied advantageously to highly reflecting objects of moderate temperatures (emitting no visible radiation), where conventional methods fail. A set of data is collected by radiance measurement m a number of n narrow spectral bands. These data represent numerical values for a set of analytical equations of the radiation

V. Tank; H. Dietl

1990-01-01

249

Small field diode correction factors derived using an air core fibre optic scintillation dosimeter and EBT2 film.  

PubMed

There is no commercially available real-time dosimeter that can accurately measure output factors for field sizes down to 4 mm without the use of correction factors. Silicon diode detectors are commonly used but are not dosimetrically water equivalent, resulting in energy dependence and fluence perturbation. In contrast, plastic scintillators are nearly dosimetrically water equivalent. A fibre optic dosimeter (FOD) with a 0.8 mm(3) plastic scintillator coupled to an air core light guide was used to measure the output factors for Novalis/BrainLab stereotactic cones of diameter 4-30 mm and Novalis MLC fields of width 5-100 mm. The FOD data matched the output factors measured by a 0.125 cm(3) Semiflex ion chamber for the MLC fields above 30 mm and those measured with the EBT2 radiochromic film for the cones and MLC fields below 30 mm. Relative detector readings were obtained with four diode types (IBA SFD, EFD, PFD, PTW 60012) for the same fields. Empirical diode correction factors were determined by taking the ratio of FOD output factors to diode relative detector readings. The diodes were found to over-respond by 3%-16% for the smallest field. There was good agreement between different diodes of the same model number. PMID:22505592

Ralston, Anna; Liu, Paul; Warrener, Kirbie; McKenzie, David; Suchowerska, Natalka

2012-05-01

250

Correction of temperature-induced spectral variations by loading space standardization.  

PubMed

With a view to maintaining the validity of multivariate calibration models for chemical processes affected by temperature fluctuations, loading space standardization (LSS) is proposed. Through the application of LSS, multivariate calibration models built at temperatures other than those of the test samples can provide predictions with an accuracy comparable to the results obtained at a constant temperature. Compared with other methods, designed for the same purpose, such as continuous piecewise direct standardization, LSS has the advantages of straightforward implementation and good performance. The methodology was applied to shortwave NIR spectral data sets measured at different temperatures. The results showed that LSS can effectively remove the influence of temperature variations on the spectra and maintain the predictive abilities of the multivariate calibration models. PMID:15732921

Chen, Zeng-Ping; Morris, Julian; Martin, Elaine

2005-03-01

251

Mller-Plesset (MP2) energy correction using tensor factorization of the grid-based two-electron integrals  

NASA Astrophysics Data System (ADS)

We present a tensor-structured method for calculating the Mller-Plesset (MP2) correction to the Hartree-Fock energy with reduced computational cost. The approach originates from the 3D grid-based low-rank factorization of the two-electron integrals tensor performed by the purely algebraic optimization. The computational scheme benefits from fast multilinear algebra implemented on separable representations of transformed two-electron integrals, doubles amplitude tensors, and other fourth order data arrays. The separation rank estimates are discussed. The so-called quantized approximation of the long skeleton vectors comprising tensor factorizations of the main entities allows a reduction in storage costs. A detailed description of tensor algorithms for evaluating the MP2 energy correction is presented. The efficiency of these algorithms is illustrated in the framework of Hartree-Fock calculations for compact molecules, including the amino acids alanine and glycine.

Khoromskaia, V.; Khoromskij, B. N.

2014-01-01

252

Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices  

DOEpatents

A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

Horn, Kevin M.

2013-07-09

253

Corrections for Thermal Expansion in Thermal Conductivity Measurement of Insulations Using the High-Temperature Guarded Hot-Plate Method  

NASA Astrophysics Data System (ADS)

The anticipation of recently published European product standards for industrial thermal insulation has driven improvements in high-temperature thermal conductivity measurements in an attempt to obtain overall measurement uncertainties better than 5 % ( k = 2). The two measurement issues that are focused on in this article are the effect of thermal expansion on in situ thickness measurement and on determining the metering area at high temperatures. When implementing in situ thickness measurements, it is vital to correct the thermal expansion of components in a high-temperature guarded hot plate (HTGHP). For example, in the NPL HTGHP this could cause 3.2 % measurement error for a 50 mm thick specimen at 800 C. The thermal expansion data for nickel 201 measured by NPL are presented, and the effect of this on the metering area of NPL's heater plate (nickel 201) is discussed.

Wu, Jiyu; Morrell, Roger

2012-02-01

254

Improved Color-Temperature Relations and Bolometric Corrections for Cool Stars  

Microsoft Academic Search

We present new grids of colors and bolometric corrections for F-K stars\\u000ahaving 4000 K < Teff < 6500 K, 0.0 < log g < 4.5 and -3.0 < [Fe\\/H] < 0.0. A\\u000acompanion paper extends these calculations into the M giant regime. Colors are\\u000atabulated for Johnson U-V and B-V; Cousins V-R and V-I; Johnson-Glass V-K, J-K\\u000aand H-K;

A. V. Sweigart; M. L. Houdashelt; R. A. Bell

1999-01-01

255

Improved Color-Temperature Relations and Bolometric Corrections for Cool Stars  

Microsoft Academic Search

We present new grids of colors and bolometric corrections for F-K stars having 4000 K<=Teff<=6500 K, 0.0<=logg<=4.5, and -3.0<=[Fe\\/H]<=0.0. A companion paper extends these calculations into the M giant regime (3000 K<=Teff<=4000 K). Colors are tabulated for Johnson U-V and B-V, Cousins V-R and V-I, Johnson-Glass V-K, J-K, and H-K, and CIT\\/CTIO V-K, J-K, H-K, and CO. We have developed

M. L. Houdashelt; R. A. Bell; A. V. Sweigart

2000-01-01

256

A novel single-stage single-phase DC uninterruptible power supply with power-factor correction  

Microsoft Academic Search

Nowadays, DC uninterruptible power supply (DC-UPS) systems are becoming a reliable solution in order to improve the efficiency in switch-mode power supplies. An important challenge in the incorporation of power factor correction and fast dynamic output response is low-cost power electronic hardware. This paper describes a novel and simple DC-UPS structure, which offers excellent characteristics in terms of cost, size,

E. Rodriguez; D. Abud; J. Arau

1999-01-01

257

Juvenile Correctional Workers' Perceptions ofSuicide Risk Factors andMental Health Issues ofIncarcerated Juveniles  

Microsoft Academic Search

Correctional staff knowledge, attitudes, andperceptions of incarcerated juveniles' mental health needs, including suicide prevention, havenotbeenstudied empirically. Thisstudy measured juvenile correc- tional officers' knowledge andattitudes regarding suicide risk factors and mental health andsubstance abuse issues through administration ofthe Mental Health Knowledge andAttitude Test(MHKAT)before andafter astaff training onsuicide prevention. Seventy-six participants completed thepre-andpost-training MHKAT.Theydemonstrated significant improvement inknowledge ofandattitudes toward mental health treat-

Joseph V. Penn; L. A. R. Stein; BA Anthony Spirito

258

Implementation of three-level AC\\/DC\\/AC converter with power factor correction and harmonic reduction  

Microsoft Academic Search

This paper proposes a three-level AC\\/DC\\/AC converter. A single-phase double-voltage power factor correction circuit to improve the power quality and provide two capacitor voltages in the input side of the AC\\/DC\\/AC converter and a three-level PWM inverter to reduce the harmonic contents of the inverter output voltages for induction motor drive are presented. In the rectifier side, the hysteresis current

Bor-Ren Lin; Hsin-Hung Lu; Yaow-Ming Chen

1998-01-01

259

Three-phase 15kVA UPS system with power factor correction and high frequency transformer isolation  

Microsoft Academic Search

This work proposes a double conversion three-phase uninterruptible power system (UPS) with power factor correction, and high frequency (HF) transformer isolation. It's suitable for operation with line-to-line input voltages equal to 220 V or 380 V. For both input voltages, the proposed converter has almost the same efficiency processing the same output power. The front-end converter is based on three

Ren P. T. Bascop; Carlos G. C. Branco; Ccero M. T. Cruz; Gilberto F. S. Filho; Luiz D. S. Bezerra

2009-01-01

260

Sustained phenotypic correction of hemophilia B dogs with a factor IX null mutation by liver-directed gene therapy  

Microsoft Academic Search

Hemophilia B is an X-linked coagulopathy caused by absence of functional coagula- tion factor IX (FIX). Using adeno-associ- ated virus (AAV)-mediated, liver-directed gene therapy, we achieved long-term (> 17 months) substantial correction of canine hemophilia B in 3 of 4 animals, including 2 dogs with an FIX null mutation. This was accomplished with a comparatively low dose of 1 3

Jane D. Mount; Roland W. Herzog; D. Michael Tillson; Susan A. Goodman; Nancy Robinson; Mark L. McCleland; Dwight Bellinger; Timothy C. Nichols; Valder R. Arruda; Clinton D. Lothrop Jr; Katherine A. High

2002-01-01

261

Critical Factors in Mental Health Programming for Juveniles in Corrections Facilities  

ERIC Educational Resources Information Center

Juveniles with mental health and other specialized needs are overrepresented in the juvenile justice system, and while juvenile corrections have not historically provided standardized and evidence-based mental health services for its incarcerated youth, the demand is evident. The reality is that juveniles with serious mental illness are committed

Underwood, Lee A.; Phillips, Annie; von Dresner, Kara; Knight, Pamela D.

2006-01-01

262

Monte Carlo study of thermal flux profiles and body correction factors for body protein measurements of obese subjects.  

PubMed

In previous calculations for Total Body Nitrogen measurements of children, the anterior/posterior thermal neutron flux profile with depth was found to be fairly flat after an initial rise. However, for obese adults significant variations are found in the flux profile with the central flux value being as low as 20% of the peak value. The significance of these flux variations is examined. Correction factors are calculated for the varying attenuation of the nitrogen and hydrogen photons by a range of obese bodies. The calculations included the effect of the thermal flux profile as well as that of an outer layer of low nitrogen content adipose tissue. The bodies are assumed to have a homogeneous hydrogen content. A study of four obese body models with varying sex and fat content shows that the correction factors do not vary much between males and females. This is surprising since the female models are assumed to have a surface fat layer twice as thick as for the male models. The correction factors are found to be only slightly sensitive to the thermal flux variations with depth. PMID:2029238

McGregor, B J; Allen, B J

1991-03-01

263

A simple method to correct for the temperature lag in TL glow-curve measurements  

NASA Astrophysics Data System (ADS)

Temperature lags between the heating element and the sample are known to exists during a thermoluminescence measurement. The experimental difficulties associated with the temperature lag can be quite serious, when one wants to extract physical information from the glow curves, because it is obviously essential to know the sample's temperature rather than that of the heating element. In the present work approximate relations to estimate the temperature lag between the heating element and the dosemeter and the effective heating rate 0022-3727/31/16/017/img5 across the sample are proposed. Preliminary experimental tests of the proposed equations are performed on LiF:Mg, Ti and 0022-3727/31/16/017/img6 and on data taken from the literature.

Kitis, G.; Tuyn, J. W. N.

1998-08-01

264

On the Correct Form of the Saha Equation for Two-Temperature Plasmas  

Microsoft Academic Search

Two quite different Saha equations modified to a two-temperature plasma were proposed and employed in many literatures. In order to clear up this confusion phenomenon lasted for a few decades in the community of thermal plasma science and technology, this paper re-examines the thermodynamic derivation of the two-temperature Saha equations. It is pointed out that the modified Saha equation deduced

Peng Han; Xi Chen; He-ping Li

1999-01-01

265

On the use of the correction factor with Japanese ozonesonde data  

NASA Astrophysics Data System (ADS)

In submitting data to the World Meteorological Organization (WMO) World Ozone and Ultraviolet Data Center (WOUDC), numerous ozonesonde stations include a correction factor (CF) that multiplies ozone concentration profile data so that the columns computed agree with column measurements from co-located ground-based and/or overpassing satellite instruments. We evaluate this practice through an examination of data from four Japanese ozonesonde stations: Kagoshima, Naha, Sapporo, and Tsukuba. While agreement between the sonde columns and Total Ozone Mapping Spectrometer (TOMS) or Ozone Mapping Instrument (OMI) is improved by use of the CF, agreement between the sonde ozone concentrations reported near the surface and data from surface monitors near the launch sites is negatively impacted. In addition, we find the agreement between the mean sonde columns without the CF and the ground-based Dobson instrument columns is improved by ~1.5 % by using the McPeters et al. (1997) balloon burst climatology rather than the constant mixing ratio assumption (that has been used for the data in the WOUDC archive) for the above burst height column estimate. Limited comparisons of coincident ozonesonde profiles from Hokkaido University with those in the WOUDC database suggest that while the application of the CFs in the stratosphere improves agreement, it negatively impacts the agreement in the troposphere. Finally and importantly, unexplained trends and changing trends in the CFs appear over the last 20 years. The overall trend in the reported CFs for the four Japanese ozonesonde stations from 1990-2010 is (-0.264 0.036) 10-2 yr-1; but from 1993-1999 the trend is (-2.18 0.14) 10-2 yr-1 and from 1999-2009 is (1.089 0.075) 10-2 yr-1, resulting in a statistically significant difference in CF trends between these two periods of (3.26 0.16) 10-2 yr-1. Repeating the analysis using CFs derived from columns computed using the balloon-burst climatology, the trends are somewhat reduced, but remain statistically significant. Given our analysis, we recommend the following: (1) use of the balloon burst climatology is preferred to a constant mixing ratio assumption for determining total column ozone with sonde data; (2) if CFs are applied, their application should probably be restricted to altitudes above the tropopause; (3) only sondes that reach at least 32 km (10.5 hPa) before bursting should be used in data validation and/or ozone trend studies if the constant mixing ratio assumption is used to calculate the above burst column (as is the case for much of the data in the WOUDC archive). Using the balloon burst climatology, sondes that burst above 29 km (~16 hPa), and perhaps lower, can be used; and (4) all ozone trend studies employing Japanese sonde data should be revisited after a careful examination of the impact of the CF on the calculated ozone trends.

Morris, G. A.; Labow, G.; Akimoto, H.; Takigawa, M.; Fujiwara, M.; Hasebe, F.; Hirokawa, J.; Koide, T.

2013-02-01

266

Quantum-Shell Corrections to the Finite-Temperature Thomas-Fermi-Dirac Statistical Model of the Atom  

SciTech Connect

Quantum-shell corrections are made directly to the finite-temperature Thomas-Fermi-Dirac statistical model of the atom by a partition of the electronic density into bound and free components. The bound component is calculated using analytic basis functions whose parameters are chosen to minimize the energy. Poisson's equation is solved for the modified density, thereby avoiding the need to solve Schroedinger's equation for a self-consistent field. The shock Hugoniot is calculated for aluminum: shell effects characteristic of quantum self-consistent field models are fully captures by the present model.

Ritchie, A B

2003-07-22

267

Separating temperature from other factors in phenological measurements  

NASA Astrophysics Data System (ADS)

Phenological observations offer a simple and effective way to measure climate change effects on the biosphere. While some species in northern mixed forests show a highly sensitive site preference to microenvironmental differences (i.e., the species is present in certain areas and absent in others), others with a more plastic environmental response (e.g., Acer saccharum, sugar maple) allow provisional separation of the universal "background" phenological variation caused by in situ (possibly biological/genetic) variation from the microclimatic gradients in air temperature. Moran's I tests for spatial autocorrelation among the phenological data showed significant (? ? 0.05) clustering across the study area, but random patterns within the microclimates themselves, with isolated exceptions. In other words, the presence of microclimates throughout the study area generally results in spatial autocorrelation because they impact the overall phenological development of sugar maple trees. However, within each microclimate (where temperature conditions are relatively uniform) there is little or no spatial autocorrelation because phenological differences are due largely to randomly distributed in situ factors. The phenological responses from 2008 and 2009 for two sugar maple phenological stages showed the relationship between air temperature degree-hour departure and phenological change ranged from 0.5 to 1.2 days earlier for each additional 100 degree-hours. Further, the standard deviations of phenological event dates within individual microclimates (for specific events and years) ranged from 2.6 to 3.8 days. Thus, that range of days is inferred to be the "background" phenological variation caused by factors other than air temperature variations, such as genetic differences between individuals.

Schwartz, Mark D.; Hanes, Jonathan M.; Liang, Liang

2013-09-01

268

A Hybrid Framework to Bias Correct and Empirically Downscale Daily Temperature and Precipitation from Regional Climate Models  

NASA Astrophysics Data System (ADS)

Bias correction and statistical downscaling are widely used approaches for postprocessing climate simulations generated by global and/or regional climate models. The skills of these approaches are typically assessed in terms of their ability to reproduce historical climate conditions as well as the plausibility and consistency of the derived statistical indicators needed by end users. Current bias correction and downscaling approaches often do not adequately satisfy the two criteria of accurate prediction and unbiased estimation. To overcome this limitation, a hybrid regression framework was developed to both minimize prediction errors and preserve the distributional characteristics of climate observations. Specifically, the framework couples the loss functions of standard (linear or nonlinear) regression methods with a regularization term that penalizes for discrepancies between the predicted and observed distributions. The proposed framework can also be extended to generate physically-consistent outputs across multiple response variables, and to incorporate both reanalysis-driven and GCM-driven RCM outputs into a unified learning framework. The effectiveness of the framework is demonstrated using daily temperature and precipitation simulations from the North American Regional Climate Change Program (NARCCAP) . The accuracy of the framework is comparable to standard regression methods, but, unlike the standard regression methods, the proposed framework is able to preserve many of the distribution properties of the response variables, akin to bias correction approaches such as quantile mapping and bivariate geometric quantile mapping.

Tan, P.; Abraham, Z.; Winkler, J. A.; Perdinan, P.; Zhong, S. S.; Liszewska, M.

2013-12-01

269

Equation of state in a strong magnetic field - Finite temperature and gradient corrections  

Microsoft Academic Search

The equation of state for condensed matter in a strong magnetic field is constructed. The regime for which statistical models and spherical Wigner-Seitz lattice cells are valid approximations is treated. The equation of state for a free nonrelativistic homogeneous electron gas in a uniform magnetic field is examined as a function of temperature, after which this treatment is refined by

Andrew M. Abrahams; Stuart L. Shapiro

1991-01-01

270

Stability correction functions for the mean wind speed and temperature in the unstable surface layer  

Microsoft Academic Search

In accordance with a theoretical analysis by Kader and Yaglom, interpolation expressions are proposed for the Monin-Obukhov functions for the wind speed and temperature profiles under unstable conditions in the surface layer of the atmospheric boundary layer. The values of the parameters are adjusted to agree with earlier work under weak instability, as reviewed by Hgstrm. The resulting formulations are

Wilfried Brutsaert

1992-01-01

271

Spectral Sensitivity Corrections for Optical Standard Pyrometers  

Microsoft Academic Search

A new method is proposed to deal with the spectral width of optical pyrometers. A constant reference wavelength and a radiance correction factor are introduced instead of a temperature dependent effective wavelength as is used in the conventional method.

J. Bezemer

1974-01-01

272

Use of SiC band gap temperature dependence for absolute calibration of emissivity corrected pyrometers in III-nitride MOVPE  

Microsoft Academic Search

In this paper we will demonstrate a new method for temperature calibration by using the in-situ measured band-gap shift of SiC in conjunction with real-time emissivity corrected pyrometry. The complete procedure for temperature calibration and real-time wafer temperature measurement on transparent substrates will be presented.

R. Steins; N. Kaluza; H. Hardtdegen; M. Zorn; K. Haberland; J.-T. Zettler

2004-01-01

273

A high performance uninterruptible power supply system with power factor correction  

Microsoft Academic Search

In this paper a simplified sinusoidal uninterruptible power supply (UPS) system is presented. The proposed scheme includes features such as high power factor, low total harmonic distortion and good dynamic response on the output voltage. This scheme has the desirable features of high efficiency, simple circuit and low cost compared to a traditional standalone multiple stages UPS with power factor

R. Caceres; N. Vazquez; C. Aguilar; J. Alvarez; I. Barbi; J. Arau

1997-01-01

274

Nuclear-polarization correction to the bound-electron g factor in heavy hydrogenlike ions.  

PubMed

The influence of nuclear polarization on the bound-electron g factor in heavy hydrogenlike ions is investigated. Numerical calculations are performed for the K- and L-shell electrons taking into account the dominant virtual nuclear excitations. This determines the ultimate limit for tests of QED utilizing measurements of the bound-electron g factor in highly charged ions. PMID:12190457

Nefiodov, A V; Plunien, G; Soff, G

2002-08-19

275

Solid state temperature-dependent NUC (non-uniformity correction) in uncooled LWIR (long-wave infrared) imaging system  

NASA Astrophysics Data System (ADS)

In uncooled LWIR microbolometer imaging systems, temperature fluctuations of FPA (Focal Plane Array) as well as lens and mechanical components placed along the optical path result in thermal drift and spatial non-uniformity. These non-idealities generate undesirable FPN (Fixed-Pattern-Noise) that is difficult to remove using traditional, individual shutterless and TEC-less (Thermo-Electric Cooling) techniques. In this paper we introduce a novel single-image based processing approach that marries the benefits of both statistical scene-based and calibration-based NUC algorithms, without relying neither on extra temperature reference nor accurate motion estimation, to compensate the resulting temperature-dependent non-uniformities. Our method includes two subsequent image processing steps. Firstly, an empirical behavioral model is derived by calibrations to characterize the spatio-temporal response of the microbolometric FPA to environmental and scene temperature fluctuations. Secondly, we experimentally establish that the FPN component caused by the optics creates a spatio-temporally continuous, low frequency, low-magnitude variation of the image intensity. We propose to make use of this property and learn a prior on the spatial distribution of natural image gradients to infer the correction function for the entire image. The performance and robustness of the proposed temperature-adaptive NUC method are demonstrated by showing results obtained from a 640512 pixels uncooled LWIR microbolometer imaging system operating over a broad range of temperature and with rapid environmental temperature changes (i.e. from -5C to 65C within 10 minutes).

Cao, Yanpeng; Tisse, Christel-Loic

2013-06-01

276

Experimental derivation of wall correction factors for ionization chambers used in high dose rate 192Ir source calibration.  

PubMed

At present there are no specific primary standards for 192Ir high dose rate sources used in brachytherapy. Traceability to primary standards is guaranteed through the method recommended by the AAPM that derives the air kerma calibration factor for the 192Ir gamma rays as the average of the air kerma calibration factors for x-rays and 137Cs gamma-rays or the Marchal et al. method that uses the energy-weighted air kerma calibration factors for 250 kV x rays and 60Co gamma rays as the air kerma calibration factor for the 192Ir gamma rays. In order to use these methods, it is necessary to use the same buildup cap for all energies and the appropriate wall correction factor for each chamber. This work describes experimental work used to derive the A(W) for four different ionization chambers and different buildup cap materials for the three energies involved in the Marchal et al. method. The A(W) for the two most common ionization chambers used in hospitals, the Farmer NE 2571 and PTW N30001 is 0.995 and 0.997, respectively, for 250 kV x rays, 0.982 and 0.985 for 192Ir gamma rays, and 0.979 and 0.991 for 60Co gamma rays, all for a PMMA build-up cap of 0.550 gm cm(-2). A comparison between the experimental values and Monte Carlo calculations shows an agreement better than 0.9%. Availability of the A(W) correction factors for all commercial chambers allows users of the in-air calibration jig, provided by the manufacturer, to alternatively use the Marchal et al. method. Calibration laboratories may also used this method for calibration of a well-type ionization chamber with a comparable accuracy to the AAPM method. PMID:11833542

Marchal, M H; de Almeida, C E; Ferreira, I H; Sibata, C H

2002-01-01

277

A transient, Hex-Z nodal code corrected by discontinuity factors. Volume 1: The transient nodal code; Final report  

SciTech Connect

This document constitutes Volume 1 of the Final Report of a three-year study supported by the special Research Grant Program for Nuclear Energy Research set up by the US Department of Energy. The original motivation for the work was to provide a fast and accurate computer program for the analysis of transients in heavy water or graphite-moderated reactors being considered as candidates for the New Production Reactor. Thus, part of the funding was by way of pass-through money from the Savannah River Laboratory. With this intent in mind, a three-dimensional (Hex-Z), general-energy-group transient, nodal code was created, programmed, and tested. In order to improve accuracy, correction terms, called {open_quotes}discontinuity factors,{close_quotes} were incorporated into the nodal equations. Ideal values of these factors force the nodal equations to provide node-integrated reaction rates and leakage rates across nodal surfaces that match exactly those edited from a more exact reference calculation. Since the exact reference solution is needed to compute the ideal discontinuity factors, the fact that they result in exact nodal equations would be of little practical interest were it not that approximate discontinuity factors, found at a greatly reduced cost, often yield very accurate results. For example, for light-water reactors, discontinuity factors found from two-dimensional, fine-mesh, multigroup transport solutions for two-dimensional cuts of a fuel assembly provide very accurate predictions of three-dimensional, full-core power distributions. The present document (volume 1) deals primarily with the specification, programming and testing of the three-dimensional, Hex-Z computer program. The program solves both the static (eigenvalue) and transient, general-energy-group, nodal equations corrected by user-supplied discontinuity factors.

Shatilla, Y.A.M.; Henry, A.F.

1993-12-31

278

Metabolic Correction of Congenital Erythropoietic Porphyria with iPSCs Free of Reprogramming Factors  

PubMed Central

Congenital erythropoietic porphyria (CEP) is due to a deficiency in the enzymatic activity of uroporphyrinogen III synthase (UROS); such a deficiency leads to porphyrin accumulation and results in skin lesions and hemolytic anemia. CEP is a candidate for retrolentivirus-mediated gene therapy, but recent reports of insertional leukemogenesis underscore the need for safer methods. The discovery of induced pluripotent stem cells (iPSCs) has opened up new horizons in gene therapy because it might overcome the difficulty of obtaining sufficient amounts of autologous hematopoietic stem cells for transplantation and the risk of genotoxicity. In this study, we isolated keratinocytes from a CEP-affected individual and generated iPSCs with two excisable lentiviral vectors. Gene correction of CEP-derived iPSCs was obtained by lentiviral transduction of a therapeutic vector containing UROS cDNA under the control of an erythroid-specific promoter shielded by insulators. One iPSC clone, free of reprogramming genes, was obtained with a single proviral integration of the therapeutic vector in a genomic safe region. Metabolic correction of erythroblasts derived from iPSC clones was demonstrated by the disappearance of fluorocytes. This study reports the feasibility of porphyria gene therapy with the use of iPSCs.

Bedel, Aurelie; Taillepierre, Miguel; Guyonnet-Duperat, Veronique; Lippert, Eric; Dubus, Pierre; Dabernat, Sandrine; Mautuit, Thibaud; Cardinaud, Bruno; Pain, Catherine; Rousseau, Benoit; Lalanne, Magalie; Ged, Cecile; Duchartre, Yann; Richard, Emmanuel; de Verneuil, Hubert; Moreau-Gaudry, Francois

2012-01-01

279

Metabolic correction of congenital erythropoietic porphyria with iPSCs free of reprogramming factors.  

PubMed

Congenital erythropoietic porphyria (CEP) is due to a deficiency in the enzymatic activity of uroporphyrinogen III synthase (UROS); such a deficiency leads to porphyrin accumulation and results in skin lesions and hemolytic anemia. CEP is a candidate for retrolentivirus-mediated gene therapy, but recent reports of insertional leukemogenesis underscore the need for safer methods. The discovery of induced pluripotent stem cells (iPSCs) has opened up new horizons in gene therapy because it might overcome the difficulty of obtaining sufficient amounts of autologous hematopoietic stem cells for transplantation and the risk of genotoxicity. In this study, we isolated keratinocytes from a CEP-affected individual and generated iPSCs with two excisable lentiviral vectors. Gene correction of CEP-derived iPSCs was obtained by lentiviral transduction of a therapeutic vector containing UROS cDNA under the control of an erythroid-specific promoter shielded by insulators. One iPSC clone, free of reprogramming genes, was obtained with a single proviral integration of the therapeutic vector in a genomic safe region. Metabolic correction of erythroblasts derived from iPSC clones was demonstrated by the disappearance of fluorocytes. This study reports the feasibility of porphyria gene therapy with the use of iPSCs. PMID:22795135

Bedel, Aurlie; Taillepierre, Miguel; Guyonnet-Duperat, Vronique; Lippert, Eric; Dubus, Pierre; Dabernat, Sandrine; Mautuit, Thibaud; Cardinaud, Bruno; Pain, Catherine; Rousseau, Benot; Lalanne, Magalie; Ged, Ccile; Duchartre, Yann; Richard, Emmanuel; de Verneuil, Hubert; Moreau-Gaudry, Franois

2012-07-13

280

Correction Factor for Gaussian Deconvolution of Optically Thick Linewidths in Homogeneous Sources  

NASA Technical Reports Server (NTRS)

Profiles of optically thick, non-Gaussian emission line profiles convoluted with Gaussian instrumental profiles are constructed, and are deconvoluted on the usual Gaussian basis to examine the departure from accuracy thereby caused in "measured" linewidths. It is found that "measured" linewidths underestimate the true linewidths of optically thick lines, by a factor which depends on the resolution factor r congruent to Doppler width/instrumental width and on the optical thickness tau(sub 0). An approximating expression is obtained for this factor, applicable in the range of at least 0 <= tau(sub 0) <= 10, which can provide estimates of the true linewidth and optical thickness.

Kastner, S. O.; Bhatia, A. K.

1999-01-01

281

Partial correction of a severe molecular defect in hemophilia A, because of errors during expression of the factor VIII gene  

SciTech Connect

Although the molecular defect in patients in a Japanese family with mild to moderately severe hemophilia A was a deletion of a single nucleotide T within an A{sub 8}TA{sub 2} sequence of exon 14 of the factor VIII gene, the severity of the clinical phenotype did not correspond to that expected of a frameshift mutation. A small amount of functional factor VIII protein was detected in the patient`s plasma. Analysis of DNA and RNA molecules from normal and affected individuals and in vitro transcription/translation suggested a partial correction of the molecular defect, because of the following: (i) DNA replication/RNA transcription errors resulting in restoration of the reading frame and/or (ii) {open_quotes}ribosomal frameshifting{close_quotes} resulting in the production of normal factor VIII polypeptide and, thus, in a milder than expected hemophilia A. All of these mechanisms probably were promoted by the longer run of adenines, A{sub 10} instead of A{sub 8}TA{sub 2}, after the delT. Errors in the complex steps of gene expression therefore may partially correct a severe frameshift defect and ameliorate an expected severe phenotype. 36 refs., 6 figs.

Young, M.; Antonarakis, S.E. [Univ. of Geneva (Switzerland); Inaba, Hiroshi [Tokyo Medical College (Japan)] [and others

1997-03-01

282

Estimating the age of immature Chrysomya albiceps (Diptera: Calliphoridae), correcting for temperature and geographical latitude.  

PubMed

Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D (0)) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671-682, 2000). Comparison with the K and D (0) values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D (0) is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis. PMID:17899152

Richards, Cameron S; Paterson, Iain D; Villet, Martin H

2008-07-01

283

Temperature-dependent immunoreactive assay to screen for digoxin-like immunoreactive factor(s).  

PubMed

Endogenous circulating digoxin-like immunoreactive factors (DLIF) are known to cross-react with antibodies to digoxin and to inhibit Na+/K(+)-transporting ATPase (Na+K+ATPase; EC 3.6.1.37). Moreover, increasing the immunoassay temperature from 4 to 37 degrees C markedly decreases DLIF from human cord serum. We tested several compounds, including hormonal steroids, bile salts, lipids, and methionine-enkephalin, for their ability to cross-react with two commercially available 125I digoxin RIAs, to inhibit porcine Na+K+ATPase, and to see whether they present the same incubation temperature dependence as human cord serum. Except for methionine-enkephalin, all compounds were inhibitors of Na+K+ATPase in the range of 1-10 mmol/L. Progesterone exhibited the highest cross-reactivity in the two RIAs. The apparent digoxin immunoreactivity for the majority of the cross-reacting steroids, bile salts, and linoleic acid was markedly decreased by increasing the incubation temperature from 4 to 37 degrees C, whereas estriol, pregnanediol, and nonspecific compounds (e.g., ethanol, human serum albumin) did not appear to be temperature-sensitive. Both lysophosphatidyl lipids gave an increased apparent digoxin concentration with increasing incubation temperature. Our data suggest that numerous weakly cross-reactive compounds can parallel the response of human cord serum. However, the temperature-dependent effect could be an additional criterion for identifying DLIF. PMID:1718632

Gudeney, X; Chanez, C; Grenier, A; Scherrmann, J M

1991-11-01

284

Development and Reliability of a Correction Factor for Parent-Reported Adherence to Pediatric Antiepileptic Drug Therapy  

PubMed Central

Purpose Study aims were 1) to document and examine associations between parent-report and electronic monitoring of pediatric antiepileptic drug adherence, 2) determine the sensitivity and specificity of parent -reported adherence, and 3) develop a correction factor for parent -reported adherence. Methods Participants included 111 consecutive children with new-onset epilepsy (Mage = 7.2 2.0; 61.3% males; 75.8% Caucasian) and their primary caregivers. Antiepileptic drug adherence was electronically monitored for three months prior to the 4-month clinic follow-up visit. parent-reported adherence captured adherence one-week prior to the clinic visit. For specificity/sensitivity analyses of parent-reported adherence, cut-points of 50%, 80%, and 90% were used with electronically-monitored adherence calculated one-week prior to the clinic visit as the reference criterion. Results Electronically monitored adherence (80.3%) was significantly lower than parent-reported adherence (96.5%; p < 0.0001) one-week prior to the clinic visit, but both were significantly correlated (rho=0.46, p < 0.001). The 90% parent-reported adherence cut-point demonstrated the most sensitivity and specificity to electronically monitored adherence; however, specificity was still only 28%. A correction factor of 0.83 was identified as a reliable adjustment for parent-reported adherence when compared to electronically monitored adherence. Discussion Although electronic monitoring is the gold standard of adherence measurement for pediatric epilepsy, it is often not clinically feasible to integrate it into routine clinical care. Thus, use of a correction factor for interpreting parent-reported adherence holds promise as a reliable clinical tool. With reliable adherence measurement, clinicians can provide adherence interventions with the hope of optimizing health outcomes for children with pediatric epilepsy.

Modi, Avani C.; Guilfoyle, Shanna M.; Morita, Diego A.; Glauser, Tracy A.

2010-01-01

285

In Vivo Gene Therapy of Hemophilia B: Sustained Partial Correction in Factor IX-Deficient Dogs  

NASA Astrophysics Data System (ADS)

The liver represents a model organ for gene therapy. A method has been developed for hepatic gene transfer in vivo by the direct infusion of recombinant retroviral vectors into the portal vasculature, which results in the persistent expression of exogenous genes. To determine if these technologies are applicable for the treatment of hemophilia B patients, preclinical efficacy studies were done in a hemophilia B dog model. When the canine factor IX complementary DNA was transduced directly into the hepatocytes of affected dogs in vivo, the animals constitutively expressed low levels of canine factor IX for more than 5 months. Persistent expression of the clotting. factor resulted in reductions of whole blood clotting and partial thromboplastin times of the treated animals. Thus, long-term treatment of hemophilia B patients may be feasible by direct hepatic gene therapy in vivo.

Kay, Mark A.; Rothenberg, Steven; Landen, Charles N.; Bellinger, Dwight A.; Leland, Frances; Toman, Carol; Finegold, Milton; Thompson, Arthur R.; Read, M. S.; Brinkhous, Kenneth M.; Woo, Savio L. C.

1993-10-01

286

Shear Correction Factors in Creep-Damage Analysis of Beams, Plates and Shells  

Microsoft Academic Search

Modern design rules for thin-walled structures which operate at elevated temperatures are based on the demand that the creep and may be the damage behaviour should be taken into account. In the last four decades various models including the scalar or tensor valued hardening and damage variables are established. These models reflect the influence of the deformation or the damage

Holm Altenbach; Konstantin Naumenko

2002-01-01

287

Determination of the quenching correction factors for plastic scintillation detectors in therapeutic high-energy proton beams  

PubMed Central

The plastic scintillation detectors (PSD) have many advantages over other detectors in small field dosimetry due to its high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs will undergo a quenching effect which makes the signal level reduced significantly when the detector is close to Bragg peak where the linear energy transfer (LET) for protons is very high. This study measures the quenching correction factor (QCF) for a PSD in clinical passive-scattering proton beams and investigates the feasibility of using PSDs in depth-dose measurements in proton beams. A polystyrene based PSD (BCF-12, ?0.5mm4mm) was used to measure the depth-dose curves in a water phantom for monoenergetic unmodulated proton beams of nominal energies 100, 180 and 250 MeV. A Markus plane-parallel ion chamber was also used to get the dose distributions for the same proton beams. From these results, the QCF as a function of depth was derived for these proton beams. Next, the LET depth distributions for these proton beams were calculated by using the MCNPX Monte Carlo code, based on the experimentally validated nozzle models for these passive-scattering proton beams. Then the relationship between the QCF and the proton LET could be derived as an empirical formula. Finally, the obtained empirical formula was applied to the PSD measurements to get the corrected depth-dose curves and they were compared to the ion chamber measurements. A linear relationship between QCF and LET, i.e. Birks' formula, was obtained for the proton beams studied. The result is in agreement with the literature. The PSD measurements after the quenching corrections agree with ion chamber measurements within 5%. PSDs are good dosimeters for proton beam measurement if the quenching effect is corrected appropriately.

Wang, L L W; Perles, L A; Archambault, L; Sahoo, N; Mirkovic, D; Beddar, S

2013-01-01

288

A novel uninterruptible power supply system with active power factor correction  

Microsoft Academic Search

This paper presents a simplified sinusoidal uninterruptible power supply (UPS) system. The proposed scheme includes features such as high power factor, low total harmonic distortion and good dynamic response at the AC output voltage. In addition, the scheme has the desirable characteristics, of high efficiency, simple circuit and low cost compared with a traditional standalone multiple stages UPS with power

Nimrod Vzquez; Carlos Aguilar; Jaime Arau; Ramn O. Cceres; Ivo Barbi; Jaime Alvarez Gallegos

2002-01-01

289

Simulation of a wireless power transfer system for electric vehicles with power factor correction  

Microsoft Academic Search

Wireless power transfer has been a popular topic of recent research. Most research has been done to address the limitations of coil-to-coil efficiency. However, little has been done to address the problem associated with the low input power factor with which the systems operate. This paper details the steps taken to analyze a wireless power transfer system from the view

Michael Pickelsimer; Leon Tolbert; Burak Ozpineci; John M. Miller

2012-01-01

290

Programmable input power factor correction method for switch-mode rectifiers  

SciTech Connect

A programmable method for single- and three-phase switch-mode rectifiers (SMR`s), operating with discontinuous current conduction to control input power factor close to unity, is presented. Single-phase SMR operation is based on variable turn-on time, while three-phase SMR operation is based on constant turn-on time.

Dawande, M.S. [R.K.N. Engineering Coll., Nagpur (India). Dept. of Electrical Engineering] [R.K.N. Engineering Coll., Nagpur (India). Dept. of Electrical Engineering; Dubey, G.K. [Indian Inst. of Tech., Kanpur (India). Dept. of Electrical Engineering] [Indian Inst. of Tech., Kanpur (India). Dept. of Electrical Engineering

1996-07-01

291

An Improvement on Horn's Parallel Analysis Methodology for Selecting the Correct Number of Factors to Retain.  

ERIC Educational Resources Information Center

A modification of Horn's parallel analysis is introduced that is based on the Monte Carlo simulation of the null distributions of the eigenvalues generated from a population correlation identity matrix. This modification reduces the tendency of the parallel analysis procedure to overextract or to extract poorly defined factors. (SLD)

Glorfeld, Louis W.

1995-01-01

292

The Differential CORDIC Algorithm: Constant Scale Factor Redundant Implementation without Correcting Iterations  

Microsoft Academic Search

The CORDIC algorithm is a well-known iterative method for the efficient computation of vector rotations, and trigonometric and hyperbolic functions. Basically, CORDIC performs a vector rotation which is not a perfect rotation, since the vector is also scaled by a constant factor. This scaling has to be compensated for following the CORDIC iteration. Since CORDIC implementations using conventional number systems

Herbert Dawid; Heinrich Meyr

1996-01-01

293

Harmonic measurements, analysis, and power factor correction in a modern steel manufacturing facility  

Microsoft Academic Search

Maximizing electric power transfer directly affects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These

Douglas Andrews; Martin T. Bishop; John F. Witte

1996-01-01

294

Background correction for fluorescence detection in thin-layer chromatography using factor analysis and the adaptive Kalman filter  

SciTech Connect

A method is proposed that corrects for variable background signals. This technique has been applied to the analysis of polyaromatic hydrocarbons using high-performance thin-layer chromatography with fluorescence detection. The fluorescent background from thin-layer plates was found to be highly variable, and simple background subtraction yielded imprecise and inaccurate concentration estimates. The method proposed here is based on the assumption that variable background signals can be modeled by the abstract spectra obtained from factor analysis of several background spectra, and the appropriate weighting factors can then be calculated by using the adaptive Kalman filter. It was found that the best models were obtained by selecting spectra from random locations across the thin-layer plate, as opposed to spectra from a blank lane or spectra adjacent to the analyte zone. This approach gave concentration estimates with improved accuracy and precision, in most cases, when compared to simple subtraction.

Gerow, D.D.; Rutan, S.C.

1988-05-01

295

49 CFR 192.115 - Temperature derating factor (T) for steel pipe.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation ...Design § 192.115 Temperature derating factor (T ) for steel pipe. The temperature derating factor to be used in the...

2013-10-01

296

A strain energy-based damage severity correction factor method for damage identification in plate-type structures  

NASA Astrophysics Data System (ADS)

A strain energy-based damage identification method for plate-type structures is presented. The concepts of a damage location factor (DLF) matrix and a damage severity correction factor (DSCF) matrix, which can be derived from the elemental modal strain energy, are proposed. The damage identification method using the DLF and DSCF is developed for damage localization and quantification in plate-type structures. The method consists of three steps: sensitive mode selection, damage localization, and damage quantification. The proposed method is a response-based damage identification technique which requires the modal frequencies and curvature mode shapes before and after damage. Numerical study demonstrates its viability to correctly detect the damage, approximate the damage area, and estimate the damage severity under high measurement noise and low damage severity conditions. The possibility of damage identification using the partial modal strain energy from the modal strain/curvature mode shape in one direction of plate is also explored based on the numerically simulated data. The method is further implemented on the experimental modal testing data to identify damage at three stages of increasing damage severity on a fiber-reinforced plastic (FRP) sandwich deck panel using a surface-bonded PVDF sensor array. The present DSCF-based damage identification method, as demonstrated in this study, can be used as a viable and effective technique for damage localization and quantification of plate-type structures.

Fan, Wei; Qiao, Pizhong

2012-04-01

297

Calculation of the flux attenuation and multiple scattering correction factors in time of flight technique for double differential cross section measurements.  

National Technical Information Service (NTIS)

Using Monte Carlo method technique, a computer code which simulates the time of flight experiment to measure double differential cross section was developed. The correction factor for flux attenuation and multiple scattering, that make a deformation to th...

G. Martin M. Coca R. Capote

1996-01-01

298

Quasi-Active Power Factor Correction Circuit for HB LED Driver  

Microsoft Academic Search

High brightness light emitting diodes (HB LEDs) are likely to be used for general lighting applications due to their high efficiency and longer life. The paper presents a quasi-active power factor corrector (PFC) for driving a string of HB LEDs. The single-stage PFC circuit has a high efficiency, and it does not increase the voltage\\/current stress on the active switch

Kening Zhou; Jian Guo Zhang; Subbaraya Yuvarajan; Da Feng Weng

2008-01-01

299

Power-factor correction with interleaved boost converters in continuous-inductor-current mode  

Microsoft Academic Search

The operation and design trade-offs of the interleaved boost converter in continuous inductor-current mode in a high-power-factor preregulator circuit are investigated. By using interleaved converters, an overall reduction of boost inductor and electromagnetic interference (EMI) filter volume can be achieved, together with reduced switching losses. The problem of unequal load sharing between the interleaved power stages with average current control

L. Balogh; R. Redl

1993-01-01

300

A novel single-phase AC\\/DC converter for power factor correction  

Microsoft Academic Search

A novel single-phase AC\\/DC converter with two pulsewidth modulation (PWM) schemes is proposed to draw a sinusoidal line current with nearly unity power factor, achieve balanced neutral point voltage and regulate the do bus voltage. With the aid of neutral point clamped scheme, a three-level voltage pattern will be generated on the AC side of the proposed rectifier. To track

Bor-Ren Lin; Shih-Jung Huang; Tsung-Liang Hung

2002-01-01

301

Analysis and modeling for fiber-optic gyroscope scale factor based on environment temperature.  

PubMed

To explore and reduce the nonlinear error and temperature dependency of fiber-optic gyroscope (FOG) scale factor, a scale factor modeling method based on temperature is presented in this paper. A hyperbolic curve fitting is proposed according to the characteristic of scale factor under stable temperature at first. Compared to traditional modeling methods, it shows that a higher precision model of scale factor can be obtained. Then the influence of temperature on scale factor is analyzed and then the hyperbolic curve fitting method is extended based on temperature, making it possible to work over the whole potential temperature range of the FOG without degrading the performance. This paper also provides the experimental and verification results. It can be seen that a high precision model of scale factor has been established, the temperature dependency of scale factor has been reduced effectively, and the error due to environment temperature is reduced by one order at least. PMID:22614471

Shen, Chong; Chen, Xiyuan

2012-05-10

302

Safety factor corrections to the magnetohydrodynamic internal kink mode in a tokamak  

SciTech Connect

It has long been acknowledged that the well known and frequently used stability criterion {beta}{sub p}<0.3 for the toroidal ideal magnetohydrodynamic internal kink mode in a tokamak is inaccurate for an empirically relevant safety factor. The present paper outlines the severity of the usual approximation, and presents improved analytical approximations of the general solution in M. N. Bussac, R. Pellat, D. Edery, and J. L. Soule, Phys. Rev. Lett. 35, 1638 (1975), thus providing new insights into the nature of the instability, together with simple formulas that can be incorporated into transport codes with sawtooth cycle algorithms.

Graves, J. P.; Wahlberg, C. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Department of Astronomy and Space Physics, EURATOM/VR Fusion Association, P.O. Box 515, Uppsala University, SE-751 20 Uppsala (Sweden)

2007-08-15

303

Correcting instruments applied to displacement and turbine gas meters  

Microsoft Academic Search

Correcting instruments offer an advantage over conventional chart recording instruments in that the correction factors for varying line pressures and temperatures are automatically applied to gas flow volume to give a direct readout of corrected volume. This eliminates the need for handling and integrating circular charts. MERCOR III CORRECTORS retain the flexibility, however, to be mounted with a circular chart

Comerford

1984-01-01

304

Transforming growth factor-? superfamily ligand trap ACE-536 corrects anemia by promoting late-stage erythropoiesis.  

PubMed

Erythropoietin (EPO) stimulates proliferation of early-stage erythrocyte precursors and is widely used for the treatment of chronic anemia. However, several types of EPO-resistant anemia are characterized by defects in late-stage erythropoiesis, which is EPO independent. Here we investigated regulation of erythropoiesis using a ligand-trapping fusion protein (ACE-536) containing the extracellular domain of human activin receptor type IIB (ActRIIB) modified to reduce activin binding. ACE-536, or its mouse version RAP-536, produced rapid and robust increases in erythrocyte numbers in multiple species under basal conditions and reduced or prevented anemia in murine models. Unlike EPO, RAP-536 promoted maturation of late-stage erythroid precursors in vivo. Cotreatment with ACE-536 and EPO produced a synergistic erythropoietic response. ACE-536 bound growth differentiation factor-11 (GDF11) and potently inhibited GDF11-mediated Smad2/3 signaling. GDF11 inhibited erythroid maturation in mice in vivo and ex vivo. Expression of GDF11 and ActRIIB in erythroid precursors decreased progressively with maturation, suggesting an inhibitory role for GDF11 in late-stage erythroid differentiation. RAP-536 treatment also reduced Smad2/3 activation, anemia, erythroid hyperplasia and ineffective erythropoiesis in a mouse model of myelodysplastic syndromes (MDS). These findings implicate transforming growth factor-? (TGF-?) superfamily signaling in erythroid maturation and identify ACE-536 as a new potential treatment for anemia, including that caused by ineffective erythropoiesis. PMID:24658078

Suragani, Rajasekhar N V S; Cadena, Samuel M; Cawley, Sharon M; Sako, Dianne; Mitchell, Dianne; Li, Robert; Davies, Monique V; Alexander, Mark J; Devine, Matthew; Loveday, Kenneth S; Underwood, Kathryn W; Grinberg, Asya V; Quisel, John D; Chopra, Rajesh; Pearsall, R Scott; Seehra, Jasbir; Kumar, Ravindra

2014-04-01

305

Electron beam therapy at extended SSDs: an analysis of output correction factors for a Mitsubishi linear accelerator.  

PubMed

The effects of extended source-to-surface distance (SSD) on the electron beam dose profiles were evaluated for various electron beam energies--6, 9, 12, 15 and 20 MeV-and the accuracy of various output correction methods was analysed on a Mitsubishi linear accelerator using a radiation field analyser (RFA). The dose fall-off region of the central axis depth-dose curves was nearly independent for SSDs up to 120 cm where as in the build-up region, a marginal reduction of surface dose was observed, particularly for lower energies and for smaller field sizes. Effective SSDs and virtual source distances were evaluated for field sizes ranging from 5 x 5 to 15 x 15 cm2 for various energies. Curve fitting was done with the measured outputs with various equations and coefficients were evaluated. The accuracy of the derived output correction factors by effective SSD, virtual source distance and curve-fit methods was assessed by evaluating correlation coefficients between the calculated and the measured values. The correlation coefficient was best with the linear-quadratic equation followed by the effective SSD method and the virtual source method. The output correction based on the linear-quadratic equation showed the best estimate of electron beam output at extended SSDs with an accuracy well within +/- 1%. The rapid reduction of dose due to the applicator-scattered component at d(max) point with an extended SSD was significant for the 5 x 5 cm2 applicator and lower energies. PMID:12375822

Rajasekar, D; Datta, N R; Das, K J Maria; Ayyagari, S

2002-09-21

306

Aerosol correction for remotely sensed sea surface temperatures from the National Oceanic and Atmospheric Administration advanced very high resolution radiometer  

NASA Astrophysics Data System (ADS)

This research presents the first-phase derivation and implementation of daytime aerosol correction algorithms for remotely sensed sea surface temperature (SST) from the advanced very high resolution radiometer (AVHRR) instrument flown onboard NOAA polar orbiting satellites. To accomplish this, a long-term (1990-1998), global AVHRR-buoy match-up database was created by merging the NOAA/NASA Pathfinder Atmospheres and Pathfinder Oceans data sets. The merged data set is unique in that it includes daytime estimates of aerosol optical depth (AOD) derived from AVHRR channel 1 (0.63 ?m) under global conditions of significant aerosol loading. Histograms of retrieved AOD reveal monomodal, lognormal distributions for both tropospheric and stratospheric aerosol modes. It is then shown empirically that the SST depression caused under each aerosol mode can be expressed as a linear function in two predictors, these being the slant path AOD retrieved from AVHRR channel 1 along with the ratio of channels 1 and 2 normalized reflectances. On the basis of these relationships, parametric equations are derived to provide an aerosol correction for retrievals from the daytime NOAA operational multichannel and nonlinear SST algorithms. Separate sets of coefficients are utilized for two aerosol modes: tropospheric (i.e., dust, smoke, haze) and stratospheric/tropospheric (i.e., following a major volcanic eruption). The equations are shown to significantly reduce retrieved SST bias using an independent set of match-ups. Eliminating aerosol-induced bias in both real-time and retrospective processing will enhance the utility of the AVHRR SST for the general user community and in climate research.

Nalli, Nicholas R.; Stowe, Larry L.

2002-10-01

307

Estimating population access to insecticide-treated nets from administrative data: correction factor is needed  

PubMed Central

Background Population access to insecticide-treated nets (ITN) is usually determined from survey data. However, for planning purposes it is necessary to estimate this indicator between surveys. Two different approaches are currently recommended for such estimates from administrative data, multiplying the number of ITN delivered either by 2.0 or 1.8 before dividing by the population. However, the validity of such estimates has not previously been investigated. Methods Thirty-five datasets from household surveys in sub-Saharan Africa were selected from ten different countries. The number of ITN and de-facto population from the samples was used as proxy administrative data and estimates of population access to ITN were calculated using the recommended formulae. Administrative estimates were compared to the access indicator from the survey data. Regression analysis was used to further define the relationship between administrative and survey population access. Mean number of ITN users was determined for each data set separately for households with and without enough ITN. Results Analysis of users per ITN showed that the assumption of two users per net is valid overall (median 2.00) but that it was consistently lower in households with at least one ITN for every two people (median 1.66). Using the formula number of ITN times 2.0 divided by the population to estimate population access to ITN from administrative data generally overestimated the survey access indicator. This was particularly the case at higher coverage levels, resulting in a 30 percentage-point overestimate at survey access above 80%. Using 1.8 as the multiplier for the number of ITN from administrative data improved the results but still showed a 19 percentage-point overestimate at access coverage above 80%. Regression analysis found that a factor of 1.64 provides the best prediction of the access indicator with slight underestimation at low access levels but good fit at levels above 55%. Conclusions A factor of 1.6 rather than 2.0 or 1.8 as the mean number of users per ITN provides a more accurate estimation of population access to ITN from administrative data accounting for discordant ITN-person pairs and a reduced number of ITN users when sufficient ITN are available.

2013-01-01

308

Self-absorption correction factor applied to 129I measurement by direct gamma-X spectrometry for Fucus serratus samples  

NASA Astrophysics Data System (ADS)

Self-absorption corrections have been determined for the energies characterising 129I below 40 keV in the frame of studying Fucus serratus samples by direct gamma-X spectrometry. This work was performed on a large spatio-temporal scale in order to integrate the fluctuations of the matrix. More than 200 samples monthly collected from January 1983 to December 1996 along the French Atlantic and English Channel coasts, have been measured as part of the Permanent Observatory of the radioactivity programme of the Institut de Radioprotection et de Sret Nuclaire (IRSN). A relationship has been established between experimental mass attenuation coefficients at low energy and the 40K concentrations of the samples, where the latter showed the same temporal variation as the 127I concentration (iodine stable isotope). Based on the mean correction factors determined in the present work, a simplified method is proposed to quantify the content of 129I. The direct gamma-X spectrometry results obtained in this way are in good agreement with those reported by Patti et al. (Radioprotection 23 (1988) 381) using neutron activation analysis for the samples collected between October 1983 and December 1984 at Herquemoulin, located near the La Hague reprocessing plant.

Lefvre, O.; Bouisset, P.; Germain, P.; Barker, E.; Kerlau, G.; Cagnat, X.

2003-06-01

309

Calculation of beam quality correction factors for various thimble ionization chambers using the Monte Carlo code PENELOPE.  

PubMed

The beam quality correction factor [Formula: see text] and the perturbation factor pQ, commonly considered in dosimetry with ionization chambers, were calculated for the NE2571 and the Standard Imaging A19 and A12S chambers, using the Monte Carlo simulation code PENELOPE. For the NE2571 chamber, the values of [Formula: see text] obtained are in very good agreement with those found in previous works by Wulff etal. and Muir and Rogers with the code EGSnrc and also with the experimental results summarized in the NCS code of practice. For pQ, a difference of ?0.4% has been found between our results and those obtained with EGSnrc for (60)Co and this difference increases slightly with TPR10(20) values. These factors have been calculated also for the A19 and A12S chambers of Standard Imaging. The values of [Formula: see text] show reasonable agreement with those recently calculated by Muir and Rogers and the measurements of McEwen. PMID:22277185

Erazo, Fabin; Lallena, Antonio M

2013-03-01

310

Temperature Variations and Habitability: Activity B Relating Factors that Influence Planetary Temperature and Habitability  

NSDL National Science Digital Library

In this activity, student teams create a knowledge map of the essential characteristics or factors of a planet with a habitable climate, identifying range of inputs, outputs and variables of a planetary environmental system. Identified characteristics are compared to extreme environments on Earth, such as the Antarctic or the Sahara desert, and are used to consider the real life challenge of searching for life in extreme environments. The resource includes a student data sheet, questions, teacher's guide and scoring rubric. This is Activity B of two activities in the first module, titled "Temperature variations and habitability," of the resource, Earth Climate Course: What Determines a Planet's Climate? The course aims to help students to develop an understanding of our environment as a system of human and natural processes that result in changes that occur over various space and time scales.

311

A model for correcting Workplace Protection Factors for lung deposition and other effects.  

PubMed

The Workplace Protection Factor (WPF) is a measure of the protection provided by an industrial respirator against a challenge agent. It is traditionally defined as the ratio of the ambient contaminant concentration (Co) in a worker's breathing zone to the in-facepiece contaminant concentration (Ci) that occurs during inhalation, and is determined by simultaneous concentration measurements during the time the respirator is worn. There are several sources of particulate loss that result in the overestimation of the true WPF. A model is presented to "estimate" these losses so that an adjusted or "unbiased" WPF can be calculated. This model requires three measurements: Co, Ci, and the ambient aerodynamic mass frequency particle size distribution (PSD). Both Co and Ci are expressed in units of "mass per unit volume." There are four steps to the calculation of the unbiased WPF. First, the in-facepiece PSD is estimated using the ambient PSD and a particle leak penetration curve. Second, the fraction of the in-facepiece PSD that will deposit in the lung is estimated using the in-facepiece PSD and a "reference worker" total lung deposition curve. Third, the fraction of the in-facepiece PSD that will deposit at the inlet of the sampling probe during both inhalation and exhalation is estimated using the in-facepiece PSD, the exhaled in-facepiece PSD, and published inlet deposition data. Last, the adjusted in-facepiece concentration is calculated using the estimates from steps two and three. The adjusted WPF, WPFa, is then calculated as the ratio of the measured ambient contaminant concentration and the adjusted in-facepiece concentration. PMID:8480629

Hewett, P; Pallay, B G; Gamble, J F

1993-04-01

312

Experimental determination of mode correction factors for thermal method spring constant calibration of AFM cantilevers using laser Doppler vibrometry  

NASA Astrophysics Data System (ADS)

Mode correction factors (MCFs) represent a significant adjustment to the spring constant values measured using the thermal cantilever calibration method. Usually, the ideal factor of 0.971 for a tipless rectangular cantilever is used, which adjusts the value by 3% for the first flexural mode. An experimental method for determining MCFs has been developed that relies on measuring the areas under the first few resonance peaks for the flexural mode type. Using this method, it has been shown that MCFs for the first flexural mode of commercially available atomic force microscope cantilevers actually vary from 0.95 to 1.0, depending on the shape and end mass of the cantilever. Triangular shaped cantilevers tend to lower MCFs with tipless versions providing the lowest values. Added masses (including tips) tend to increase the first flexural modes MCF to higher values with large colloid probes at the high extreme. Using this understanding and applying it to the recently developed laser Doppler vibrometry thermal calibration method it is now possible to achieve very accurate and precise cantilever spring constant calibrations (uncertainties close to 1%) with commonly available commercial cantilevers such as tipped rectangular and triangular cantilevers, and colloid probes.

Gates, Richard S.; Osborn, William A.; Pratt, Jon R.

2013-06-01

313

Temperature  

NSDL National Science Digital Library

Thermometers record the temperature in a given location. Temperature is a non-living thing because it doesn't physically move or eat, for example. However, temperature is a very important factor that effects where animals live and how long they stay in that particular spot.

Luis Miguel Orta Rial (None;)

2008-03-24

314

Temperature-stable and high Q-factor TiO2 Bragg reflector resonator  

NASA Astrophysics Data System (ADS)

The highest Q-factor resonators employ whispering gallery modes in single-crystal sapphire but have poor temperature stability. Rutile was the first dielectric material used to construct a microwave dielectric resonator. However, its very high temperature coefficient of permittivity made it unsuitable for practical applications. This paper reports a high Q-factor (50 000) and temperature-stable spherical Bragg reflector resonator based on polycrystalline rutile operating at 29.9 GHz. Temperature stability is achieved by adjusting the electric filling factor of a spherical shell so that in combination with its highly negative temperature coefficient of permittivity, the effect of thermal expansion is exactly cancelled out.

Breeze, Jonathan; Krupka, Jerzy; Centeno, Anthony; Alford, Neil Mcn

2009-02-01

315

Temperature Data Assimilation with Salinity Corrections: Validation for the NSIPP Ocean Data Assimilation System in the Tropical Pacific Ocean, 1993-1998  

NASA Technical Reports Server (NTRS)

The NASA Seasonal-to-Interannual Prediction Project (NSIPP) has developed an Ocean data assimilation system to initialize the quasi-isopycnal ocean model used in our experimental coupled-model forecast system. Initial tests of the system have focused on the assimilation of temperature profiles in an optimal interpolation framework. It is now recognized that correction of temperature only often introduces spurious water masses. The resulting density distribution can be statically unstable and also have a detrimental impact on the velocity distribution. Several simple schemes have been developed to try to correct these deficiencies. Here the salinity field is corrected by using a scheme which assumes that the temperature-salinity relationship of the model background is preserved during the assimilation. The scheme was first introduced for a zlevel model by Troccoli and Haines (1999). A large set of subsurface observations of salinity and temperature is used to cross-validate two data assimilation experiments run for the 6-year period 1993-1998. In these two experiments only subsurface temperature observations are used, but in one case the salinity field is also updated whenever temperature observations are available.

Troccoli, Alberto; Rienecker, Michele M.; Keppenne, Christian L.; Johnson, Gregory C.

2003-01-01

316

Dependence of Yb-169 absorbed dose energy correction factors on self-attenuation in source material and photon buildup in water  

SciTech Connect

Purpose: Absorbed dose energy correction factors, used to convert the absorbed dose deposited in a LiF thermoluminescent dosimeter (TLD) into the clinically relevant absorbed dose to water, were obtained for both spherical volumetric sources and for the model 4140 HDR Yb-169 source. These correction factors have a strong energy dependence below 200 keV; therefore, spectral changes were quantified as Yb-169 photons traveled through both source material (Yb{sub 2}O{sub 3}) and water with the corresponding absorbed dose energy correction factors, f(r,{theta}), calculated as a function of location in a phantom. Methods: Using the MCNP5 Monte Carlo radiation transport simulation program, the Yb-169 spectrum emerging from spherical Yb{sub 2}O{sub 3} sources (density 6.9 g/cm{sup 3}) with radii between 0.2 and 0.9 mm were analyzed and their behavior compared against those for a point-source. The absorbed dose deposited to both LiF and H{sub 2}O materials was analyzed at phantom depths of 0.1-10 cm for each source radius and the absorbed dose energy correction factor calculated as the ratio of the absorbed dose to water to that of LiF. Absorbed dose energy correction factors for the Model 4140 Yb-169 HDR brachytherapy source similarly were obtained and compared against those calculated for the Model M-19 Ir-192 HDR source. Results: The Yb-169 average spectral energy, emerging from Yb{sub 2}O{sub 3} spherical sources 0.2-0.9 mm in radius, was observed to harden from 7% to 29%; as these photons traveled through the water phantom, the photon average energy softened by as much as 28% at a depth of 10 cm. Spectral softening was dependent on the measurement depth in the phantom. Energy correction factors were found to vary both as a function of source radius and phantom depth by as much as 10% for spherical Yb{sub 2}O{sub 3} sources. The Model 4140 Yb-169 energy correction factors depended on both phantom depth and reference angle and were found to vary by more than 10% between depths of 1 and 10 cm and angles of 0 deg. and 180 deg. This was in contrast to that of the Model M-19 Ir-192 source which exhibited approximately 3.5%-4.4% variation in its energy correction factors from phantom depths of 0.5-10 cm. The absorbed dose energy correction factor for the Ir-192 source, on the other hand, was independent of angle to within 1%. Conclusions: The application of a single energy correction factor for Yb-169 TLD based dosimetry would introduce a high degree of measurement uncertainty that may not be reasonable for the clinical characterization of a brachytherapy source; rather, an absorbed dose energy correction function will need to be developed for these sources. This correction function should be specific to each source model, type of TLD used, and to the experimental setup to obtain accurate and precise dosimetric measurements.

Medich, David C.; Munro, John J. III [Radiation Laboratory, University of Massachusetts Lowell, 1 University Avenue, Lowell, Massachusetts 01854 (United States); Source Production and Equipment Co., Inc., 113 Teal Street, St. Rose, Louisiana 70087 (United States)

2010-05-15

317

Atmospheric circulation as a factor for air temperatures in Bulgaria  

NASA Astrophysics Data System (ADS)

The research period is 1950-2012, and includes data for air temperatures in 21 Bulgarian stations. Two circulation indices, covering the same period and showing west-east or south-north directions of transport of air masses, were calculated. Statistical methods were used in the study. The results show a significant positive trend in average annual air temperatures in almost the entire territory of Bulgaria with the exception of its eastern-northeastern part. The warming occurs mainly in March, June and July, with some stations having significant positive values also in January, May and August. The zonal index reveals an insignificant increase of western transport of air masses in the cold half of the year (October-April) and strengthening of the eastern transport in the rest of the year. The meridional index shows an increase of the northern transport of air masses over the entire year and this is particularly visible in March, June, August and September. Correlation coefficients indicate that atmospheric circulation has leading role in determination of air temperatures during the period from November to April. Western transport of air masses leads to higher temperatures in spring, autumn and winter and to lower temperatures in summer. The influence of ENSO on atmospheric circulation over Bulgaria is weak, with a time lag of 2 months. El Nio is associated with increased western and northern transport of air masses, while La Nia is associated with increased eastern and southern transport of air masses over southeastern Europe.

Nojarov, Peter

2014-05-01

318

Entrance dose measurements for in-vivo diode dosimetry: Comparison of correction factors for two types of commercial silicon diode detectors.  

PubMed

Silicon diode dosimeters have been used routinely for in-vivo dosimetry. Despite their popularity, an appropriate implementation of an in-vivo dosimetry program using diode detectors remains a challenge for clinical physicists. One common approach is to relate the diode readout to the entrance dose, that is, dose to the reference depth of maximum dose such as d(max) for the 10x10 cm(2) field. Various correction factors are needed in order to properly infer the entrance dose from the diode readout, depending on field sizes, target-to-surface distances (TSD), and accessories (such as wedges and compensate filters). In some clinical practices, however, no correction factor is used. In this case, a diode-dosimeter-based in-vivo dosimetry program may not serve the purpose effectively; that is, to provide an overall check of the dosimetry procedure. In this paper, we provide a formula to relate the diode readout to the entrance dose. Correction factors for TSD, field size, and wedges used in this formula are also clearly defined. Two types of commercial diode detectors, ISORAD (n-type) and the newly available QED (p-type) (Sun Nuclear Corporation), are studied. We compared correction factors for TSDs, field sizes, and wedges. Our results are consistent with the theory of radiation damage of silicon diodes. Radiation damage has been shown to be more serious for n-type than for p-type detectors. In general, both types of diode dosimeters require correction factors depending on beam energy, TSD, field size, and wedge. The magnitudes of corrections for QED (p-type) diodes are smaller than ISORAD detectors. PMID:11674824

Zhu, X R

2000-01-01

319

Basic factors controlling pest in high temperature systems  

NASA Technical Reports Server (NTRS)

The catastrophic disintegration in air at intermediate temperatures of refractory materials which are very resistant to oxidation at high temperatures is known as pest. A study was undertaken to determine whether the mechanism proposed for pest failure in silicides might also be responsible for pest failure in NbAl3. The aim was to correlate oxidation kinetics in the range where disintegration of NbAl3 is observed with delayed failure data obtained under similar conditions. Studies were also undertaken to develop some understanding of deformation mechanisms in both silicides and aluminides.

Berkowitz-Mattuck, J.; Rossetti, M.

1971-01-01

320

PHYSICOCHEMICAL FACTORS AFFECTING TOXICITY IN FRESHWATER: HARDNESS, PH, AND TEMPERATURE  

EPA Science Inventory

A search of the literature for effects of hardness, pH, or temperature on the toxicity of chemicals to freshwater organisms suggested that the amount of reliable and useful data is limited. uch of the disparity among results reported in the literature was caused by improperly des...

321

Proposal of a 5kVA single-phase on-line UPS with high frequency isolation and power factor correction  

Microsoft Academic Search

A high performance isolated double conversion uninterruptible power supply (UPS) with power factor correction using a high frequency transformer, and input voltages equal to 110 V\\/220 V is proposed. The arrangement is suitable to rack type structures because it has small size and reduced weight. For both input voltages, the proposed converter has almost the same efficiency processing the same

Ren P. T. Bascop; Carlos G. C. Branco; Ccero M. T. Cruz; Eduardo F. de Oliveira; Gean J. M. Sousa

2009-01-01

322

Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites  

NASA Technical Reports Server (NTRS)

For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

2005-01-01

323

Retrieving water surface temperature from archive LANDSAT thermal infrared data: Application of the mono-channel atmospheric correction algorithm over two freshwater reservoirs  

NASA Astrophysics Data System (ADS)

Water surface temperature is a key element in characterizing the thermodynamics of waterbodies, and for irregularly-shaped inland reservoirs, LANDSAT thermal infrared images are the best alternative yet for the retrieval of this parameter. However, images must be corrected mainly for atmospheric effects in order to be fully exploitable. The objective of this study is to validate the mono-channel correction algorithm for single-band thermal infrared LANDSAT data as put forward by Jimnez-Muoz et al. (2009). Two freshwater reservoirs in continental France were selected as study sites, and best use was made of all accessible image and field data. Results obtained are satisfactory and in accordance with the literature: r2 values are above 0.90 and root-mean-square error values are comprised between 1 and 2 C. Moreover, paired Wilcoxon signed rank tests showed a highly significant difference between field and uncorrected image data, a very highly significant difference between uncorrected and corrected image data, and no significant difference between field and corrected image data. The mono-channel algorithm is hence recommended for correcting archive LANDSAT single-band thermal infrared data for inland waterbody monitoring and study.

Simon, R. N.; Tormos, T.; Danis, P.-A.

2014-08-01

324

Factors affecting the performance of metakaolin geopolymers exposed to elevated temperatures  

Microsoft Academic Search

The effects of geopolymer binder systems exposed to elevated temperatures are examined. Geopolymers investigated were synthesized\\u000a from metakaolin, activated by combinations of sodium\\/potassium silicate and sodium\\/potassium hydroxide. The specimens were\\u000a then exposed to temperatures of 800C. The factors studied were: (1) calcining temperatures of kaolin; (2) Si\\/Al ratio of\\u000a the geopolymer; (3) activator\\/metakaolin ratio; (4) curing temperature; and (5) alkali

Daniel L. Y. Kong; Jay G. Sanjayan; Kwesi Sagoe-Crentsil

2008-01-01

325

Determination of alcohol content in beverages using short-wave near-infrared spectroscopy and temperature correction by transfer calibration procedures  

Microsoft Academic Search

This paper reports the utilization of short-wave near-infrared (SW-NIR) transmission spectroscopy for rapid and conclusive analysis of alcoholic content (%v\\/v) in beverages. This spectral region is interesting because common visible diode array spectrometers can be utilized, reducing time and costs in comparison with traditional near-infrared or mid-infrared instruments. A correction of external temperature influence is necessary, and for this purposes

Fernando D. Barboza; Ronei J. Poppi

2003-01-01

326

Low temperature coefficient of resistance and high gage factor in beryllium-doped silicon  

NASA Technical Reports Server (NTRS)

The gage factor and resistivity of p-type silicon doped with beryllium was studied as a function of temperature, crystal orientation, and beryllium doping concentration. It was shown that the temperature coefficient of resistance can be varied and reduced to zero near room temperature by varying the beryllium doping level. Similarly, the magnitude of the piezoresistance gage factor for beryllium-doped silicon is slightly larger than for silicon doped with a shallow acceptor impurity such as boron, whereas the temperature coefficient of piezoresistance is about the same for material containing these two dopants. These results are discussed in terms of a model for the piezoresistance of compensated p-type silicon.

Robertson, J. B.; Littlejohn, M. A.

1974-01-01

327

High School 9th Grade Students' Understanding Level and Misconceptions about Temperature and Factors Affecting It  

ERIC Educational Resources Information Center

The purpose of this study is to explore students' understanding levels and misconceptions about temperature and factors affecting it. The concept of the study was chosen from Geography National Curriculum. In this study, a questionnaire was developed after a pilot study with an aim to ascertain the students' understanding levels of temperature and

Akbas, Yavuz

2012-01-01

328

Dependence of Plastic TATB Shock-Wave Sensitivity on Temperature, Density and Technology Factors  

Microsoft Academic Search

Mixed TATB-based HE is the most perspective because of the manufacture and exploitation safety of its items. At the same time the safety of these explosive, at high temperatures, which take place at emergencies, causes the certain anxiety. Plastic TATB shock-wave sensitivity (SWS) researches has shown that temperature as one of the important factors of external influence is not always

Yu. A. Vlasov; V. B. Kosolapov; L. V. Fomicheva; I. P. Khabarov

1999-01-01

329

High quality factor resonance at room temperature with nanostrings under high tensile stress  

Microsoft Academic Search

Quality factors as high as 207 000 are demonstrated at room temperature for radio-frequency silicon nitride string resonators with cross sectional dimensions on the scale of 100 nm, made with a nonlithographic technique. A product of quality factor and surface to volume ratio greater than 6000 nm?1 is presented, the highest yet reported. Doubly clamped nanostring resonators are fabricated in

Scott S. Verbridge; Jeevak M. Parpia; Robert B. Reichenbach; Leon M. Bellan; H. G. Craighead

2006-01-01

330

High quality factor resonance at room temperature with nanostrings under high tensile stress  

Microsoft Academic Search

Quality factors as high as 207 000 are demonstrated at room temperature for radio-frequency silicon nitride string resonators with cross sectional dimensions on the scale of 100 nm, made with a nonlithographic technique. A product of quality factor and surface to volume ratio greater than 6000 nm-1 is presented, the highest yet reported. Doubly clamped nanostring resonators are fabricated in

Scott S. Verbridge; Jeevak M. Parpia; Robert B. Reichenbach; Leon M. Bellan; H. G. Craighead

2006-01-01

331

Factorize  

NSDL National Science Digital Library

This interactive Java applet helps students explore the relationship between area and multiplication. First, users are asked to input all factor pairs of a given number. Then, selecting each of those factor pairs, the user draws the respective rectangular array by clicking and dragging across a grid. Options include the use of the commutative property (e.g., user must enter both 2x4 and 4x2 for factors of 8 and represent them with different arrays), entering a number of the user's own choice, and an optional scoring feature allowing the user to keep track of the number correct.

2004-01-01

332

An active-clamped full-wave zero-current-switched quasi-resonant boost converter in power factor correction application  

Microsoft Academic Search

In this paper, a power factor correction (PFC) based on active-clamped full-wave quasi-resonant (ZCS-QR) boost converter is presented. This circuit is characterized by zero-voltage-switched (ZVS) and zero-current-switched (ZCS) that results in higher efficiency, opens possibility to incorporate higher switching frequency, and has some potency to reduce converter's conducted EMI. The working principle and steady state performance of the proposed converter

E. Firmansyah; S. Abe; M. Shoyama; S. Tomioka; T. Ninomiya

2010-01-01

333

Analysis and Design for a Novel Single-Stage High Power Factor Correction Diagonal Half-Bridge Forward ACDC Converter  

Microsoft Academic Search

By means of components placement, the buck-boost and diagonal half-bridge forward converters are combined to create a novel single-stage high power factor correction (HPFC) diagonal half-bridge forward converter. When both the PFC cell and dc-dc cell operate in DCM, the proposed converter can achieve HPFC and lower voltage stress of the bulk capacitor. The circuit analysis of the proposed converter

Jong-Lick Lin; Wei-Kai Yao; Sung-Pei Yang

2006-01-01

334

Calculation of perturbation correction factors for some reference dosimeters in high-energy photon beams with the Monte Carlo code PENELOPE.  

PubMed

The BNM-LNHB (formerly BNM-LPRI, the French national standard laboratory for ionizing radiation) is equipped with a SATURNE 43 linear accelerator (GE Medical Systems) dedicated to establishing national references of absorbed dose to water for high-energy photon and electron beams. These standards are derived from a dose measurement with a graphite calorimeter and a transfer procedure to water using Fricke dosimeters. This method has already been used to obtain the reference of absorbed dose to water for cobalt-60 beams. The correction factors rising from the perturbations generated by the dosimeters were determined by Monte Carlo calculations. To meet these applications, the Monte Carlo code PENELOPE was used and user codes were specially developed. The first step consisted of simulating the electron and photon showers produced by primary electrons within the accelerator head to determine the characteristics of the resulting photon beams and absorbed dose distributions in a water phantom. These preliminary computations were described in a previous paper. The second step, described in this paper, deals with the calculation of the perturbation correction factors of the graphite calorimeter and of Fricke dosimeters. To point out possible systematic biases, these correction factors were calculated with another Monte Carlo code, EGS4, widely used for years in the field of dose metrology applications. Comparison of the results showed no significant bias. When they were possible, experimental verifications confirmed the calculated values. PMID:11419629

Mazurier, J; Gouriou, J; Chauvenet, B; Barthe, J

2001-06-01

335

Correlations between transition temperature, tolerance factor and cohesive energy in 2+:4+ perovskites  

NASA Astrophysics Data System (ADS)

Cohesive energies were calculated ab initio for a range of simple 2+:4+ perovskites (A2+B4+O3). Correlations were sought between the sets of lattice parameters, cohesive energies, cubic transition temperatures and Goldschmidt tolerance factors for these compounds. There is a noticeable correlation (R = -0.60) between the transition temperatures and the tolerance factors, but only weak relationships between the cohesive energy and the other parameters. However, for more than half the set of compounds, there is a strong correlation (R = 0.989), in the form of a simple linear trend between the tolerance factor and the ratio of cubic transition temperature to cohesive energy density. The remaining compounds form two distinct clusters and either retain cubicity down to 0 K or undergo transitions to lower symmetry at substantially lower temperatures than might be expected from the trend.

Goudochnikov, Pavel; Bell, Andrew J.

2007-04-01

336

A correction factor for ablation algorithms assuming deviations of Lambert-Beer's law with a Gaussian-profile beam  

NASA Astrophysics Data System (ADS)

In this work, we propose an adjustment factor to be considered in ablation algorithms used in refractive surgery. This adjustment factor takes into account potential deviations of Lambert-Beer's law and the characteristics of a Gaussian-profile beam. To check whether the adjustment factor deduced is significant for visual function, we applied it to the paraxial Munnerlyn formula and found that it significantly influences the post-surgical corneal radius and p-factor. The use of the adjustment factor can help reduce the discrepancies in corneal shape between the real data and corneal shape expected when applying laser ablation algorithms.

Rodrguez-Marn, Francisco; Anera, Rosario G.; Alarcn, Aixa; Hita, E.; Jimnez, J. R.

2012-04-01

337

Calculation of Compressibility Factor for Air Over the Ranges of Pressure, Temperature, and Relative Humidity of Interest in Flowmeter Calibration.  

National Technical Information Service (NTIS)

A simple yet precise equation has been developed to enable calculation (using programmable calculators) of the compressibility factor, Z, for air from measurements of pressure, temperature, and humidity. The compressibility factor, a factor which accounts...

F. E. Jones

1983-01-01

338

Influence of environmental factors on infrared eye temperature measurements in cattle.  

PubMed

Environmental factors were evaluated to determine potential limitations in using cattle eye temperatures obtained through infrared thermography (IRT) for early disease detection systems or in animal welfare research studies. The effects of the following factors on IRT eye temperatures in cattle and a fabricated surrogate "eye" were evaluated: camera to object distance, wind speed, camera settings (distance, emissivity, and humidity), and solar loading. Wind speed in both live animals and using a surrogate "eye" was found to decrease the IRT temperature. In the presence of ? 7 km/h wind, the mean IRT eye temperature decreased by 0.43 0.13 C and; at higher wind speeds (? 12 km/h), the temperature decreased by 0.78 0.33 C. Direct sunlight was found to increase the IRT eye temperature by 0.56 0.36 C. It was determined that environmental factors impact IRT temperature measurements significantly and therefore must be managed to ensure reproducible and accurate readings. PMID:24290729

Church, J S; Hegadoren, P R; Paetkau, M J; Miller, C C; Regev-Shoshani, G; Schaefer, A L; Schwartzkopf-Genswein, K S

2014-02-01

339

Atmospheric correction of infrared measurements of sea surface temperature using channels at 3.7, 11 and 12 Mum  

Microsoft Academic Search

Atmospheric effects upon the radiometric determination of surface temperature were studied for channels centered at 3.7, 11 and 12 Mum. The error due to the atmosphere is least for the channel centered at 3.7 Mum, which is a real advantage. The use of a linear combination of two or all three of these channels allows one to eliminate most of

P. Y. Deschamps; T. Phulpin

1980-01-01

340

Radiosonde Temperature Measurements in Strong Inversions: Correction for Thermal Lag Based on an Experiment at the South Pole  

Microsoft Academic Search

Very steep shallow temperature inversions occur during most of the year in the near-surface layer on the Antarctic Plateau. A radiosonde carried by a balloon rising at a few meters per second does not measure such inversions accurately because the response time of the thermistor is several seconds. To quantify this error, the authors flew a radiosonde on a tethered

Ashwin Mahesh; Von P. Walden; Stephen G. Warren

1997-01-01

341

Novel, cyclic heat dissipation method for the correction of natural temperature gradients in sap flow measurements. Part 1. Theory and application.  

PubMed

Natural temperature gradient (NTG) can be a significant problem in thermal sap flow measurements, particularly in dry environments with sparse vegetation. To resolve this problem, we propose a novel correction method called cyclic heat dissipation (CHD) in its thermal dissipation probe (TDP) application. The CHD method is based on cyclic, switching ON/OFF power schema measurements and a three-exponential model, extrapolating measured signal to steady state thermal equilibrium. The extrapolated signal OFF represents NTG, whereas the extrapolated signal ON represents standard TDP signal, biased by NTG. Therefore, subtraction of the OFF signal from the ON signal allows defining the unbiased TDP signal, finally processed according to standard Granier calibration. The in vivo Kalahari measurements were carried out in three steps on four different tree species, first as NTG, then as standard TDP and finally in CHD mode, each step for ?1-2 days. Afterwards, each tree was separated from its stem following modified Roberts' (1977) procedure, and CHD verification was applied. The typical NTG varying from ?0.5 C during night-time to -1 C during day-time, after CHD correction, resulted in significant reduction of sap flux densities (J(p)) as compared with the standard TDP, particularly distinct for low J(p). The verification of the CHD method indicated ?20% agreement with the reference method, largely dependent on the sapwood area estimate. The proposed CHD method offers the following advantages: (i) in contrast to any other NTG correction method, it removes NTG bias from the measured signal by using in situ, extrapolated to thermal equilibrium signal; (ii) it does not need any specific calibration making use of the standard Granier calibration; (iii) it provides a physical background to the proposed NTG correction; (iv) it allows for power savings; (v) it is not tied to TDP, and so can be adapted to other thermal methods. In its current state, the CHD data processing is not yet fully automated. PMID:22611074

Lubczynski, Maciek W; Chavarro-Rincon, Diana; Roy, Jean

2012-07-01

342

Recombinant factor VIIa to correct coagulopathy in patients with traumatic brain injury presenting to outlying facilities before transfer to the regional trauma center.  

PubMed

Timely correction of coagulopathy in patients with traumatic brain injury (TBI) improves mortality. Recombinant, activated factor VII (VIIa) has been identified as an effective method to correct coagulopathy in patients with TBI. We performed a retrospective study (January 1, 2008-December 31, 2009) of all patients with TBI and coagulopathy (international normalized ratio (INR) > 1.5) transferred to our Level I trauma center. Twenty-three patients with coagulopathy and TBI were transferred to our trauma center, 100 per cent sustained a fall, and 100 per cent were taking warfarin at the time of injury. Ten patients received VIIa to correct coagulopathy before transfer, whereas 13 did not. The purpose of this study was to compare outcomes in patients who received VIIa with those who did not. When comparing the VIIa group with the no-VIIa group there was no difference in age, gender, Glasgow Coma Scale score, injury severity score, transfer time, or INR at outlying facility. Both groups received one unit of plasma before arrival at our trauma center; patients in the VIIa group received a single 1.2 mg dose of VIIa at the outlying facility. Upon arrival to our trauma center the VIIa group had a lower INR (1.0 vs 3.0, P = 0.02) and lower mortality (0% vs 39%, P = 0.03). In coagulopathic patients with TBI presenting to outlying institutions with limited resources to quickly provide plasma, VIIa efficiently corrects coagulopathy before transfer to definitive care at the regional trauma center. More rapid correction of coagulopathy with VIIa in this patient population may improve mortality. PMID:22273315

Brown, Carlos V R; Sowery, Lauren; Curry, Eardie; Valadka, Alex B; Glover, Cynthia S; Grabarkewitz, Kim; Green, Terry; Hail, Steve; Admire, John

2012-01-01

343

The use of a numerical filter to correct airborne temperature measurements for the effects of sensor lag  

NASA Technical Reports Server (NTRS)

A numerical filter for transforming measured temperature signals into a close approximation of the actual temperature signal is described. The filter is derived by minimizing the mean-square error of the system, and assuming a knowledge of the characteristics of the sensing element and its housing. The equation representing the frequency-response function of the numerical filter is given. Input and output spectra for a filter applied to a case with negligible noise and a noise level of 1.5 percent of the total power in the input spectrum are analyzed, and the numerical weights for these two cases are calculated. Phase angle and gain for the entire system are examined. It is noted that the filter can enhance spectral components as high as 8 Hz with little phase and gain degradation over the bandwidth.

Ritter, John A.; Smith, G. Louis; Cahoon, Donald R.

1987-01-01

344

A new method for charge-loss correction of room-temperature semiconductor detectors using digital trapezoidal pulse shaping  

NASA Astrophysics Data System (ADS)

It is well known that semiconductor detectors operating at room temperature can be read out at high rate, with good noise performance and low sensitivity to ballistic deficit, by using trapezoidal (flat-topped) pulse shaping. Nevertheless, the energy resolution of these detectors is also affected by chargetrapping inside the detector crystal, which can not be compensated by the standard trapezoidal pulse shaping. A new digital algorithm based on trapezoidal pulse shaping, to compensate for the charge-trapping effect while minimizing the electronic noise, has been developed. The application of the pulse processing algorithm to a 5 5 1 mm3 planar Schottky CdTe detector leads to an energy resolution of 1.15% FWHM at 662 keV at room temperature, which is considerably superior to the results of the standard pulse filters.

Nakhostin, M.; Veeramani, P.

2012-06-01

345

Remote temperature inversion sensor. [For correcting aerial survey measurements for uranium; using spectral radiance measurements in 15. mu. CO band  

Microsoft Academic Search

In conducting aircraft surveys for uranium, it is found that temperature inversions can give spurious results because they promote accumulation of radon gas in the atmosphere. The Bi (daughter product of radon) gamma-rays detected from the atmosphere-borne radon are difficult to separate from the Bi gamma-rays originating from the ground, and providing a signature for uranium deposits. The purpose of

W. Malkmus; M. Griggs

1977-01-01

346

Boltzmann factor and Hawking radiation  

NASA Astrophysics Data System (ADS)

Hawking radiation has thermal spectrum corresponding to the temperature TH=(8, where M is the mass (energy) of the black hole. Corrections to the Hawking radiation spectrum were discovered by Kraus and Wilczek (1995) and Parikh and Wilczek (2000). Here I show that these corrections follow directly from the basic principles of thermodynamics and statistical mechanics. In essence, it is the Boltzmann factor that ought to be corrected; corrections to the Hawking (or any other) radiation spectrum then follow necessarily.

Ryskin, Gregory

2014-06-01

347

Dependence on temperature and pixel threshold of the calibration for the Timepix detector and its correction method  

NASA Astrophysics Data System (ADS)

The semiconductor pixel detector Timepix (matrix of 256 256 pixels with 55 ?m pitch) can be used for measurements of energies of radiation quanta. For this purpose knowledge of the energy calibration of each pixel is required. Such a calibration is nonlinear. Two calibration methods already exist that use either monochromatic radiation sources or the internal test pulse capability. In the work we compare the calibrated response of the detector with the source method and for different temperatures and detector settings. Furthermore in this work we also explore the possibility of calibrating the detector under new conditions (temperature, detector settings) by adjusting an already existing calibration for different conditions. The new cross-temperature and cross-threshold calibration is calculated based on 3 original calibrations. This approach is advantageous, because it allows improving the detector response for different conditions without the need to make a whole new calibration. It is also the only appropriate method for particular applications where the detector is for instance placed in environments beyond direct physical access such as in a nuclear reactor vessel, the LHC ATLAS detector or in outer space. The method was applied and tested on a Timepix chip equipped with a 300 ?m thick Si sensor.

Turecek, D.; Jakubek, J.

2013-01-01

348

Temperature-sensitive mouse cell factors for strand-specific initiation of poliovirus RNA synthesis.  

PubMed Central

Two cell lines, TgSVA and TgSVB, were established from the kidneys of transgenic mice carrying the human gene encoding poliovirus receptor. The cells were highly susceptible to poliovirus infection, and a large amount of infectious particles was produced in the infected cells at 37 degrees C. However, the virus yield was greatly reduced at 40 degrees C. This phenomenon was common to all mouse cells tested. To identify the temperature-sensitive step(s) of the virus infection cycle, different steps of the infection cycle were examined for temperature sensitivity. The results strongly suggested that the growth restriction observed at 40 degrees C was due to reduced efficiency of the initiation process of virus-specific RNA synthesis. Furthermore, this restriction appeared to occur only on the synthesis of positive-strand RNA. Virus-specific RNA synthesis in crude replication complexes was not affected by the nonpermissive temperature of 40 degrees C. In vitro uridylylation of VPg seemed to be temperature sensitive only after prolonged incubation at 40 degrees C. These results indicate that a specific host factor(s) is involved in the efficient initiation process of positive-strand RNA synthesis of poliovirus and that the host factor(s) is temperature sensitive in TgSVA and TgSVB cells. Images

Shiroki, K; Kato, H; Koike, S; Odaka, T; Nomoto, A

1993-01-01

349

Monte Carlo modelling of diode detectors for small field MV photon dosimetry: detector model simplification and the sensitivity of correction factors to source parameterization  

NASA Astrophysics Data System (ADS)

The goal of this work was to examine the use of simplified diode detector models within a recently proposed Monte Carlo (MC) based small field dosimetry formalism and to investigate the influence of electron source parameterization has on MC calculated correction factors. BEAMnrc was used to model Varian 6?MV jaw-collimated square field sizes down to 0.5 cm. The IBA stereotactic field diode (SFD), PTW T60016 (shielded) and PTW T60017 (un-shielded) diodes were modelled in DOSRZnrc and isocentric output ratios (OR_{\\det _{MC} }^{f_{clin} }) calculated at depths of d = 1.5, 5.0 and 10.0 cm. Simplified detector models were then tested by evaluating the percent difference in OR_{det_{MC} }^{f_{clin} }between the simplified and complete detector models. The influence of active volume dimension on simulated output ratio and response factor was also investigated. The sensitivity of each MC calculated replacement correction factor (\\mathop k\

Cranmer-Sargison, G.; Weston, S.; Evans, J. A.; Sidhu, N. P.; Thwaites, D. I.

2012-08-01

350

In vivo hepatic gene therapy: complete albeit transient correction of factor IX deficiency in hemophilia B dogs.  

PubMed Central

Hemophilia B is a bleeding disorder caused by mutations in the factor IX gene. The disorder is X-linked recessive with a prevalence of about 1 in 30,000 Caucasian males. Factor IX is naturally synthesized in the liver and secreted into blood. Here we report the construction of recombinant adenoviral vectors containing the canine factor IX cDNA that are capable of transducing hepatocytes in mice at high efficiencies in vivo without partial hepatectomy. The recombinant viral vector was used to treat hemophilia B dogs by direct vector infusion into the portal vasculature of deficient animals. Plasma factor IX concentrations in the treated hemophilia B dogs increased from 0 to 300% of the level present in normal dogs, resulting in complete amelioration of the disease as demonstrated by normal blood coagulation and hemostatic measurements. Although plasma factor IX concentration started to decline after a few days, therapeutic levels of factor IX persisted for 1-2 months in the treated animals. The results validate the principle of in vivo hepatic gene delivery to reconstitute the genetic deficiency in a large animal model and suggest that gene therapy is achievable when long-acting vectors are developed. Images

Kay, M A; Landen, C N; Rothenberg, S R; Taylor, L A; Leland, F; Wiehle, S; Fang, B; Bellinger, D; Finegold, M; Thompson, A R

1994-01-01

351

The role of demagnetization factor in determining the true value of the Curie temperature  

SciTech Connect

The Curie temperature, T{sub c}, is the temperature above which a material loses its long-range ferromagnetic order. Considering the equation of state of a ferromagnet in the mean-field approximation it has been shown theoretically that the value of the demagnetization factor N has a significant influence on the perceived location of T{sub c} on the temperature scale. A series of precise measurements of magnetization using two differently shaped single crystals of high-purity gadolinium was carried out to prove this result experimentally and develop a procedure leading to the 'true' value of T{sub c}.

Zverev, V.I.; Gimaev, R.R.; Tishin, A.M.; Mudryk, Ya; Gschneidner, Jr., K.A.; Pecharsky, V.K.

2011-05-20

352

Adenoviral-mediated overexpression of platelet-derived growth factor-B corrects ischemic impaired wound healing.  

PubMed

Chronic wounds represent a major clinical problem with significant morbidity and healthcare expenditures, but no effective therapies. Topical platelet-derived growth factor-BB trials have required large and repeated doses to achieve only a modest effect. We examined the ability of an adenovirus containing the platelet-derived growth factor-B transgene to improve the rate of wound healing through induction of platelet-derived growth factor-B overexpression in cells participating in the wound healing response. We treated excisional wounds in the ischemic rabbit ear, which have a 60% delay in healing, with vehicle, 106, or 108 plaque-forming units of an adenovirus containing the platelet-derived growth factor-B per wound (n = 19). At 7 d this resulted in a decrease in the epithelial gap from 3.4 +/- 1 mm (mean +/- SD) in vehicle-treated wounds to 1.9 +/- 1.8 mm (mean +/- SD, p < 0.05) when treated with 106 plaque-forming units of an adenovirus containing the platelet-derived growth factor-B, and 0.7 +/- 1.1 mm (mean +/- SD, p < 0.001) when treated with 108 plaque-forming units of an adenovirus containing the platelet-derived growth factor-B. Ischemic excisional wounds treated with 108 plaque-forming units of an adenovirus containing the platelet-derived growth factor-B even healed more rapidly than non-ischemic excisional wounds treated with vehicle (p < 0.05). In contrast, 5 microg of platelet-derived growth factor-BB protein (n = 2) resulted in only modest granulation tissue at the margin, but no significant differences in epithelial gap (3 +/- 0.6 mm, mean +/- SD). Plaque-forming units (106 or 108) of an adenovirus containing the beta-galactosidase transgene (n = 4) impaired wound re-epithelialization with an epithelial gap of 5.11 +/- 0.69 mm, mean +/- SD, p < 0.004, and 3.8 +/- 0.57 mm, mean +/- SD, p < 0.07, respectively. Adenoviral-mediated gene transfer of platelet-derived growth factor-B overcame the ischemic defect in wound healing and offers promise in the treatment of chronic nonhealing wounds. The vulnerary effects of platelet-derived growth factor-B overexpression were sufficient to overcome the adverse effects of the adenovirus or transgene on wound healing. PMID:10469337

Liechty, K W; Nesbit, M; Herlyn, M; Radu, A; Adzick, N S; Crombleholme, T M

1999-09-01

353

WINDOW-WALL INTERFACE CORRECTION FACTORS: THERMAL MODELING OF INTEGRATED FENESTRATION AND OPAQUE ENVELOPE SYSTEMS FOR IMPROVED PREDICTION OF ENERGY USE  

SciTech Connect

The boundary conditions for thermal modeling of fenestration systems assume an adiabatic condition between the fenestration system installed and the opaque envelope system. This theoretical adiabatic boundary condition may not be appropriate owing to heat transfer at the interfaces, particularly for aluminum- framed windows affixed to metal- framed walls. In such scenarios, the heat transfer at the interface may increase the discrepancy between real world thermal indices and laboratory measured or calculated indices based on NFRC Rating System.This paper discusses the development of window-wall Interface Correction Factors (ICF) to improve energy impacts of building envelope systems

Bhandari, Mahabir S [ORNL; Ravi, Dr. Srinivasan [University of Florida, Gainesville

2012-01-01

354

Factors affecting preconditioning of Trichinella spiralis nativa larvae in musculature to low temperatures.  

PubMed Central

The influence of preconditioning temperature, length of the preconditioning period, host and age of the infection on the survival of Trichinella spiralis nativa larvae in musculature to low temperature refrigeration was investigated. Dogs, foxes, ferrets, mink and guinea pigs were infected with a T. spiralis nativa isolate, killed at various times postinfection, preconditioned at temperature of -10 degrees C, -15 degrees C or -20 degrees C for varying periods of time prior to low temperature refrigeration and subsequent pepsin digestion to determine survival of larvae. The preconditioning temperature played an important role in the subsequent survival of larvae in musculature at low refrigeration temperatures. Under the conditions of this study, survival of larvae was greater as the preconditioning temperature became lower. The minimum period of preconditioning required had an inverse relationship with the refrigeration temperature. Preconditioning of the T. spiralis nativa isolate used occurred in the musculature of guinea pigs, foxes, ferrets, mink and dogs with larvae surviving longer in vulpine and canine musculature than in the other hosts studied. Age of the infection was not a major factor in the survival of preconditioned larvae in musculature at low refrigeration temperatures although survival was slightly longer in older infections.

Smith, H J

1987-01-01

355

Factors affecting preconditioning of Trichinella spiralis nativa larvae in musculature to low temperatures.  

PubMed

The influence of preconditioning temperature, length of the preconditioning period, host and age of the infection on the survival of Trichinella spiralis nativa larvae in musculature to low temperature refrigeration was investigated. Dogs, foxes, ferrets, mink and guinea pigs were infected with a T. spiralis nativa isolate, killed at various times postinfection, preconditioned at temperature of -10 degrees C, -15 degrees C or -20 degrees C for varying periods of time prior to low temperature refrigeration and subsequent pepsin digestion to determine survival of larvae. The preconditioning temperature played an important role in the subsequent survival of larvae in musculature at low refrigeration temperatures. Under the conditions of this study, survival of larvae was greater as the preconditioning temperature became lower. The minimum period of preconditioning required had an inverse relationship with the refrigeration temperature. Preconditioning of the T. spiralis nativa isolate used occurred in the musculature of guinea pigs, foxes, ferrets, mink and dogs with larvae surviving longer in vulpine and canine musculature than in the other hosts studied. Age of the infection was not a major factor in the survival of preconditioned larvae in musculature at low refrigeration temperatures although survival was slightly longer in older infections. PMID:3607648

Smith, H J

1987-04-01

356

Correction of murine galactosialidosis by bone marrow-derived macrophages overexpressing human protective protein/cathepsin A under control of the colony-stimulating factor-1 receptor promoter  

PubMed Central

Galactosialidosis (GS) is a human neurodegenerative disease caused by a deficiency of lysosomal protective protein/cathepsin A (PPCA). The GS mouse model resembles the severe human condition, resulting in nephropathy, ataxia, and premature death. To rescue the disease phenotype, GS mice were transplanted with bone marrow from transgenic mice overexpressing human PPCA specifically in monocytes/macrophages under the control of the colony stimulating factor-1 receptor promoter. Transgenic macrophages infiltrated and resided in all organs and expressed PPCA at high levels. Correction occurred in hematopoietic tissues and nonhematopoietic organs, including the central nervous system. PPCA-expressing perivascular and leptomeningeal macrophages were detected throughout the brain of recipient mice, although some neuronal cells, such as Purkinje cells, continued to show storage and died. GS mice crossed into the transgenic background reflected the outcome of bone marrow-transplanted mice, but the course of neuronal degeneration was delayed in this model. These studies present definite evidence that macrophages alone can provide a source of corrective enzyme for visceral organs and may be beneficial for neuronal correction if expression levels are sufficient.

Hahn, Christopher N.; del Pilar Martin, Maria; Zhou, Xiao-Yan; Mann, Linda W.; d'Azzo, Alessandra

1998-01-01

357

The Aquarius Scatterometer: An Active System for Measuring Surface Roughness for Sea-Surface Brightness Temperature Correction  

NASA Technical Reports Server (NTRS)

The Aquarius scatterometer is a total-power L-band radar system for estimating ocean surface roughness. Its measurements will enable the removal of wind effects from the Aquarius radiometer ocean-surface brightness temperature measurements being used to retrieve ocean salinity. The Aquarius scatterometer is a relatively simple, low-spatial resolution power-detecting radar, without ranging capability. But to meet its science requirement, it must be very stable, with repeatability on the order of 0.1 dB over several days, and calibrated accuracy to this level over several months. Data from this instrument over land as well as ocean areas will be available for a variety of geophysical applications.

Freedman, Adam; McWatters, Dalia; Spencer, Michael

2006-01-01

358

FACTORS INFLUENCING YEAR-CLASS STRENGTH OF PERCIDS: A SUMMARY AND A MODEL OF TEMPERATURE EFFECTS  

EPA Science Inventory

Factors regulating year-class strength in the percid genera Stizostedion and Perca are summarized. Some index of water temperature regime correlates significantly with year-class strength of percids in many waterbodies, in several lakes in North America. A probablistic model is p...

359

Exchange interactions and local-moment fluctuation corrections in ferromagnets at finite temperatures based on noncollinear density-functional calculations  

NASA Astrophysics Data System (ADS)

We explore the derivation of interatomic exchange interactions in ferromagnets within density-functional theory (DFT) and the mapping of DFT results onto a spin Hamiltonian. We delve into the problem of systems comprising atoms with strong spontaneous moments together with atoms with weak induced moments. All moments are considered as degrees of freedom, with the strong moments thermally fluctuating only in angle and the weak moments thermally fluctuating in angle and magnitude. We argue that a quadratic dependence of the energy on the weak local moments magnitude, which is a good approximation in many cases, allows for an elimination of the weak-moment degrees of freedom from the thermodynamic expressions in favor of a renormalization of the Heisenberg interactions among the strong moments. We show that the renormalization is valid at all temperatures accounting for the thermal fluctuations and resulting in temperature-independent renormalized interactions. These are shown to be the ones directly derived from total-energy DFT calculations by constraining the strong-moment directions, as is done, e.g., in spin-spiral methods. We furthermore prove that within this framework the thermodynamics of the weak-moment subsystem, and in particular all correlation functions, can be derived as polynomials of the correlation functions of the strong-moment subsystem with coefficients that depend on the spin susceptibility and that can be calculated within DFT. These conclusions are rigorous under certain physical assumptions on the measure in the magnetic phase space. We implement the scheme in the full-potential linearized augmented plane wave method using the concept of spin-spiral states, considering applicable symmetry relations and the use of the magnetic force theorem. Our analytical results are corroborated by numerical calculations employing DFT and a Monte Carlo method.

Leai?, Marjana; Mavropoulos, Phivos; Bihlmayer, Gustav; Blgel, Stefan

2013-10-01

360

Beyond temperature and precipitation: ecological risk factors that modify malaria transmission.  

PubMed

Being able to identify the ecological factors that impact risk for malaria would confer important predictive capacity to target malaria control interventions in a community. Temperature and water available for breeding habitats have been shown to be important primary ecological factors that impact the distribution of the malaria vectors and the rate at which the mosquito and parasite develop. However, to this point, studies focusing on the local level have been met with many inconsistent results when assessing malaria risk using both temperature and precipitation. This paper reviewed existing literature to determine if other ecological factors beyond temperature and water are present that may be modifying any associations present between ecological factors and malaria risk. It was found that the ability for water to pool and persist, water quality, elevation, deforestation, and agriculture have all been associated with malaria and may be modifying risk. Using the primary and modifying ecological variables, identifying the interactions between these factors and specific thresholds for increased malaria risk is critical: filling this knowledge gap would enable communities to develop tailored malaria control interventions targeted to their specific circumstances. PMID:20727338

Stresman, Gillian H

2010-12-01

361

Evaluation of weldment creep and fatigue strength-reduction factors for elevated-temperature design  

SciTech Connect

New explicit weldment strength criteria in the form of creep and fatigue strength-reduction factors were recently introduced into the American Society of Mechanical Engineers Code Case N-47, which governs the design of elevated-temperature nuclear plants components in the United States. This paper provides some of the background and logic for these factors and their use, and it describes the results of a series of long-term, confirmatory, creep-rupture and fatigue tests of simple welded structures. The structures (welded plates and tubes) were made of 316 stainless steel base metal and 16-8-2 weld filler metal. Overall, the results provide further substantiation of the validity of the strength-reduction factor approach for ensuring adequate life in elevated-temperature nuclear component weldments. 16 refs., 7 figs.

Corum, J.M.

1989-01-01

362

Relations of Tualatin River water temperatures to natural and human-caused factors  

USGS Publications Warehouse

Aquatic research has long shown that the survival of cold-water fish, such as salmon and trout, decreases markedly as water temperatures increase above a critical threshold, particularly during sensitive life stages of the fish. In an effort to improve the overall health of aquatic ecosystems, the State of Oregon in 1996 adopted a maximum water-temperature standard of 17.8 degrees Celsius (68 degrees Fahrenheit), based on a 7-day moving average of daily maximum temperatures, for most water bodies in the State. Anthropogenic activities are not permitted to raise the temperature of a water body above this level. In the Tualatin River, a tributary of the Willamette River located in northwestern Oregon, water temperatures periodically surpass this threshold during the low-flow summer and fall months.An investigation by the U.S. Geological Survey quantified existing seasonal, diel, and spatial patterns of water temperatures in the main stem of the river, assessed the relation of water temperatures to natural climatic conditions and anthropogenic factors (such as wastewater-treatment-plant effluent and modification of riparian shading), and assessed the impact of various flow management practices on stream temperatures. Half-hourly temperature measurements were recorded at 13 monitoring sites from river mile (RM) 63.9 to RM 3.4 from May to November of 1994. Four synoptic water- temperature surveys also were conducted in the upstream and downstream vicinities of two wastewater-treatment-plant outfalls. Temperature and streamflow time-series data were used to calibrate two dynamic-flow heat-transfer models, DAFLOW-BLTM (RM 63.9-38.4) and CE-QUAL-W2 (RM 38.4-3.4).Simulations from the models provided a basis for approximating 'natural' historical temperature patterns, performing effluent and riparian-shading sensitivity analyses, and evaluating mitigation management scenarios under 1994 climatic conditions. Findings from the investigation included (1) under 'natural' conditions the temperature of the river would exceed the State standard of 17.8 degrees Celsius at many locations during the low-flow season, (2) current operation of wastewater-treatment plants increases the temperature of the river downstream of the plants under low-flow conditions, (3) river temperature is significantly affected by riparian shade variations along both the tributaries and the main stem, (4)flow releases during the low-flow season from the Henry Hagg Lake reservoir decrease the river temperature in the upper section, and (5) removal of a low diversion dam at RM 3.4 would slightly decrease temperatures below RM 10.0.

Risley, John C.

1997-01-01

363

PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) regulates auxin biosynthesis at high temperature  

PubMed Central

At high ambient temperature, plants display dramatic stem elongation in an adaptive response to heat. This response is mediated by elevated levels of the phytohormone auxin and requires auxin biosynthesis, signaling, and transport pathways. The mechanisms by which higher temperature results in greater auxin accumulation are unknown, however. A basic helix-loop-helix transcription factor, PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), is also required for hypocotyl elongation in response to high temperature. PIF4 also acts redundantly with its homolog, PIF5, to regulate diurnal growth rhythms and elongation responses to the threat of vegetative shade. PIF4 activity is reportedly limited in part by binding to both the basic helix-loop-helix protein LONG HYPOCOTYL IN FAR RED 1 and the DELLA family of growth-repressing proteins. Despite the importance of PIF4 in integrating multiple environmental signals, the mechanisms by which PIF4 controls growth are unknown. Here we demonstrate that PIF4 regulates levels of auxin and the expression of key auxin biosynthesis genes at high temperature. We also identify a family of SMALL AUXIN UP RNA (SAUR) genes that are expressed at high temperature in a PIF4-dependent manner and promote elongation growth. Taken together, our results demonstrate direct molecular links among PIF4, auxin, and elongation growth at high temperature.

Franklin, Keara A.; Lee, Sang Ho; Patel, Dhaval; Kumar, S. Vinod; Spartz, Angela K.; Gu, Chen; Ye, Songqing; Yu, Peng; Breen, Gordon; Cohen, Jerry D.; Wigge, Philip A.; Gray, William M.

2011-01-01

364

Should Quaternary sea-level changes be used to correct glacier ELAs, vegetation belt altitudes and sea level temperatures for inferring climate changes?  

NASA Astrophysics Data System (ADS)

Changes in the altitudes of glacier snowlines (ELAs) and the altitudes of montane vegetation belts (VBAs) measure Quaternary climatic change. An accepted 'correction' to such changes by deducting the amount of contemporary sea level fall is wrong, since the air displaced by the ice sheets approximately fills the space left by the falling sea level and so there is no overall downward movement of the troposphere. This also causes a reduced cooling at the lowered sea level relative to that at the former inter-glacial sea level, about 1C at the Las Glacial Maximum, which reduces the discrepancies previously noted by others between terrestrial and marine estimates of sea-level cooling. The change in temperature is indicated by the product of the ELA or VBA lowering and the environmental lapse rate (ELR). Prior estimates of ?ELA (-900 135 m) and ELR (-6 0.1C km -1) would indicate a cooling of -5.4C at interglacial sea level and -4.4C at glacial sea level, although glacial-period ELRs are not known reliably. Established ELA corrections for local epeirogenic uplift or subsidence are appropriate.

Osmaston, Henry A.

2006-03-01

365

Proteomic comparison of Ralstonia solanacearum strains reveals temperature dependent virulence factors  

PubMed Central

Background Ralstonia solanacearum, the causal agent of bacterial wilt, is a genetically diverse bacterial plant pathogen present in tropical and subtropical regions of the world that infects more than 200 plant species, including economically important solanaceous crops. Most strains of R. solanacearum are only pathogenic at temperatures between 25 to 30C with strains that can cause disease below 20C considered a threat to agriculture in temperate areas. Identifying key molecular factors that distinguish strains virulent at cold temperatures from ones that are not is needed to develop effective management tools for this pathogen. We compared protein profiles of two strains virulent at low temperature and two strains not virulent at low temperature when incubated in the rhizosphere of tomato seedlings at 30 and 18C using quantitative 2D DIGE gel methods. Spot intensities were quantified and compared, and differentially expressed proteins were sequenced and identified by mass spectrometry (MS/MS). Results Four hundred and eighteen (418) differentially expressed protein spots sequenced produced 101 unique proteins. The identified proteins were classified in the Gene Ontology biological processes categories of metabolism, cell processes, stress response, transport, secretion, motility, and virulence. Identified virulence factors included catalase (KatE), exoglucanase A (ChbA), drug efflux pump, and twitching motility porin (PilQ). Other proteins identified included two components of a putative type VI secretion system. We confirmed differential expression of 13 candidate genes using real time PCR techniques. Global regulators HrpB and HrpG also had temperature dependent expression when quantified by real time PCR. Conclusions The putative involvement of the identified proteins in virulence at low temperature is discussed. The discovery of a functional type VI secretion system provides a new potential virulence mechanism to explore. The global regulators HrpG and HrpB, and the protein expression profiles identified suggest that virulence at low temperatures can be partially explained by differences in regulation of virulence factors present in all the strains.

2014-01-01

366

Calcite saturation, foraminiferal test mass, and Mg/Ca-based temperatures dissolution corrected using XDXA 150 ka record from the western Indian Ocean  

NASA Astrophysics Data System (ADS)

record of deep-sea calcite saturation >(?>[CO 32->]>), derived from X-ray computed tomography-based foraminifer dissolution index, XDX, was constructed for the past 150 ka for a core from the deep (4157 m) tropical western Indian Ocean. G. sacculifer and N. dutertrei recorded a similar dissolution history, consistent with the process of calcite compensation. Peaks in calcite saturation (15 mol/kg higher than the present-day value) occurred during deglaciations and early in MIS 3. Dissolution maxima coincided with transitions to colder stages. The mass record of G. sacculifer better indicated preservation than did that of N. dutertrei or G. ruber. Dissolution-corrected Mg/Ca-derived SST records, like other SST records from marginal Indian Ocean sites, showed coolest temperatures of the last 150 ka in early MIS 3, when mixed layer temperatures were 4C lower than present SST. Temperatures recorded by N. dutertrei showed the thermocline to be 4C colder in MIS 3 compared to the Holocene (8 ka B.P.).

Johnstone, Heather J. H.; Kiefer, Thorsten; Elderfield, Henry; Schulz, Michael

2014-03-01

367

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications  

SciTech Connect

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

Onar, Omer C [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL; Chinthavali, Madhu Sudhan [ORNL] [ORNL; Campbell, Steven L [ORNL] [ORNL; Miller (JNJ), John M. [JNJ-Miller PLC] [JNJ-Miller PLC

2014-01-01

368

Electron beam quality correction factors for plane-parallel ionization chambers: Monte Carlo calculations using the PENELOPE system  

Microsoft Academic Search

Simulations of three plane-parallel ionization chambers have been used to determine directly the chamber- and quality-dependent factors fc,Q, instead of the product (sw,air p)Q, and k_{Q,Q_o} (or k_{Q,Q_int} ) for a broad range of electron beam qualities (4-20 MeV) using divergent monoenergetic beams and phase-space data from two accelerators. An original calculation method has been used which circumvents the weakness

Josep Sempau; Pedro Andreo; Judith Aldana; Jocelyne Mazurier; Francesc Salvat

2004-01-01

369

Blackbody-radiation correction to the polarizability of helium  

SciTech Connect

The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric gas thermometry using helium or argon.

Puchalski, M. [Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60-780 Poznan (Poland); Jentschura, U. D. [Missouri University of Science and Technology, Rolla, Missouri 65409-0640 (United States); Mohr, P. J. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8420 (United States)

2011-04-15

370

Finite-temperature dynamical structure factor of the Heisenberg-Ising chain  

NASA Astrophysics Data System (ADS)

We consider the spin-1/2 Heisenberg XXZ chain in the regime of large Ising-type anisotropy ? . By a combination of duality and Jordan-Wigner transformations we derive a mapping to weakly interacting spinless fermions, which represent domain walls between the two degenerate ground states. We develop a perturbative expansion in 1/? for the transverse dynamical spin structure factor at finite temperatures and in an applied transverse magnetic field. We present a unified description for both the low-energy temperature-activated response and the temperature evolution of the T=0 two-spinon continuum. We find that the two-spinon continuum narrows in energy with increasing temperature. At the same time spectral weight is transferred from the two-spinon continuum to the low-energy intraband scattering continuum, which is strongly peaked around the position of the (single) spinon dispersion (Villain mode).

James, A. J. A.; Goetze, W. D.; Essler, F. H. L.

2009-06-01

371

Influence of anelastic corrections to the temperature derivatives of seismic velocities on 3-D wavefields in geodynamically derived seismic mantle heterogeneity  

NASA Astrophysics Data System (ADS)

Recently, we have developed a new joint forward modeling approach to test geodynamic hypotheses directly against seismic data: Seismic heterogeneity is predicted by converting the temperature field of a high-resolution 3-D mantle circulation model into seismic velocities using thermodynamic models of mantle mineralogy. 3-D global wave propagation in the synthetic elastic structures is then simulated using a spectral element method. Being based on forward modelling only, this approach allows us to generate synthetic wavefields and seismograms independently of seismic observations. The statistics of observed long-period body wave traveltime variations show a markedly different behaviour for P- and S-waves: the standard deviation of P-wave delay times stays almost constant with ray turning depth, while that of the S-wave delay times increases strongly throughout the mantle. In an earlier study, we showed that synthetic traveltime variations computed for an isochemical mantle circulation model with strong core heating can reproduce these different trends. This was taken as a strong indication that seismic heterogeneity in the lower mantle is likely dominated by thermal variations on large length-scales; that is, relevant for long-period body waves. To test the robustness of our earlier conclusion, we address now the question on the influence of anelasticity on the standard deviation of synthetic traveltime variations. Owing to the differences in seismic frequency content between laboratory measurements (MHz to GHz) and the Earth (mHz to Hz), the seismic velocities given in the mineralogical model need to be adjusted; that is, corrected for dispersion due to anelastic effects. This correction will increase the sensitivity of the seismic velocities to temperature variations. The magnitude of this increase in sensitivity depends on absolute temperature, frequency, the frequency dependence of attenuation and the activation enthalpy of the dissipative process. Especially the latter two are poorly known for mantle minerals and our results show that variations in activation enthalpy produce the largest differences in temperature sensitivity with respect to the purely elastic case. We will present new wave propagation simulations and corresponding statistical analyses of traveltime measurements for different synthetic seismic models spanning the possible range of anelastic velocity conversions while being based on the same mantle circulation model.

Schuberth, Bernhard; Grber, Claudia; Baykiev, Eldar; Zaroli, Christophe

2014-05-01

372

Correlation between behavioral deficits and decreased brain-derived neurotrophic [correction of neurotrofic] factor in neonatal meningitis.  

PubMed

We investigated the correlation between memory impairment and hippocampal brain-derived neurotrophic factor (BDNF) levels in adult rats submitted to experimental meningitis (Streptococcus pneumoniae) in the neonatal period. Sixty days after inoculation the animals were submitted to the behavior tasks and hippocampal BDNF protein were evaluated. In the meningitis group, there was impairment in habituation and avoidance memory and a decrease in the BDNF levels. The decrease in hippocampal BDNF levels correlated to impairment in memory in adult animals submitted to experimental meningitis in the neonatal period. PMID:20452683

Barichello, Tatiana; Belarmino, Eraldo; Comim, Clarissa M; Cipriano, Andreza L; Generoso, Jaqueline S; Savi, Geovana D; Stertz, Laura; Kapczinski, Flvio; Quevedo, Joo

2010-06-01

373

Long-Term Expression of Human Coagulation Factor VIII and Correction of Hemophilia A after in vivo Retroviral Gene Transfer in Factor VIII-Deficient Mice  

Microsoft Academic Search

Hemophilia A is caused by a deficiency in coagulation factor VIII (FVIII) and predisposes to spontaneous bleeding that can be life-threatening or lead to chronic disabilities. It is well suited for gene therapy because a moderate increase in plasma FVIII concentration has therapeutic effects. Improved retroviral vectors expressing high levels of human FVIII were pseudotyped with the vesicular stomatitis virus

Thierry Vandendriessche; Veerle Vanslembrouck; Inge Goovaerts; Hans Zwinnen; Marie-Line Vanderhaeghen; Desire Collen; Marinee K. L. Chuah

1999-01-01

374

Temperature dependence and Debye-Waller factors for resonant x-ray Raman scattering in solids  

NASA Astrophysics Data System (ADS)

Resonant x-ray Raman scattering is a strongly coherent process. The well defined phase relations between scattering channels through the core excited states localized at different atoms result in a conservation of the electronic crystal momentum. However, as we show here, the zero-point and thermal vibrations dephase these scattering channels and lead to incoherent contributions with different spectral shapes. The relative strength of the coherent and incoherent contributions are found to strongly depend on temperature via a Debye-Waller factor. This results in a characteristic temperature dependence of the spectral profile of the resonant x-ray Raman scattering.

Gel'mukhanov, Faris; Privalov, Timofei; gren, Hans

2000-12-01

375

Calculated influence of temperature-related factors on ozone formation rates in the lower troposphere  

SciTech Connect

Using an atmospheric chemical reaction mechanism applied to air parcels near the Earth`s surface, the sensitivities of ozone (O3) formation rates are quantified for changes in four meteorologically controlled parameters: temperature, sunlight intensity, water vapor mixing ratio, and isoprene concentration. Over a wide range of NO(x) and anthropogenic hydrocarbon concentrations, enhanced photolysis rates and elevated isoprene concentrations are calculated to be the most important factors contributing to increased O3 formation rates in warmer days. These results suggest that the most uncertain yet important meteorological factor controlling regional-scale O3 formation is fractional cloudiness and its impact on photolysis rates.

Walcek, C.J.; Yuan, H.H. [State Univ. of New York, Albany, NY (United States)] [State Univ. of New York, Albany, NY (United States)

1995-05-01

376

Electron beam quality correction factors for plane-parallel ionization chambers: Monte Carlo calculations using the PENELOPE system.  

PubMed

Simulations of three plane-parallel ionization chambers have been used to determine directly the chamber- and quality-dependent factors fc,Q, instead of the product (Sw,air p)Q, and kQ,Q0 (or kQ,Q,int) for a broad range of electron beam qualities (4-20 MeV) using divergent monoenergetic beams and phase-space data from two accelerators. An original calculation method has been used which circumvents the weakness of the so far assumed independence between stopping-power ratios and perturbation factors. Very detailed descriptions of the geometry and materials of the chambers have been obtained from the manufacturers, and prepared as input to the PENELOPE 2003 Monte Carlo system using a computer code that includes correlated sampling and particle splitting. Values of the beam quality factors have been determined for the case of an electron reference beam. The calculated values have been compared with those in the IAEA TRS-398 dosimetry protocol and the differences analysed. The results for a NACP-02 chamber show remarkably good agreement with TRS-398 at high electron beam qualities but differ slightly at low energies. Arguments to explain the differences include questioning the undemonstrated assumption that the NACP is a 'perturbation-free' chamber even at very low electron beam energies. Results for Wellhfer PPC-40 and PPC-05 chambers cannot be compared with data from others for these chambers because no calculations or reliable experimental data exist. It has been found that the results for the PPC-40 are very close to those of a Roos chamber, but the values for the PPC-05 are considerably different from those of a Markus chamber, and rather approach those of a Roos chamber. Results for monoenergetic electrons and accelerator phase-space data have been compared to assess the need for detailed and costly simulations, finding very small differences. This questions the emphasis given in recent years to the use of 'realistic' source data for accurate electron beam dosimetry. PMID:15509075

Sempau, Josep; Andreo, Pedro; Aldana, Judith; Mazurier, Jocelyne; Salvat, Francesc

2004-09-21

377

Electron beam quality correction factors for plane-parallel ionization chambers: Monte Carlo calculations using the PENELOPE system  

NASA Astrophysics Data System (ADS)

Simulations of three plane-parallel ionization chambers have been used to determine directly the chamber- and quality-dependent factors fc,Q, instead of the product (sw,air p)Q, and k_{Q,Q_o} (or k_{Q,Q_int} ) for a broad range of electron beam qualities (4-20 MeV) using divergent monoenergetic beams and phase-space data from two accelerators. An original calculation method has been used which circumvents the weakness of the so far assumed independence between stopping-power ratios and perturbation factors. Very detailed descriptions of the geometry and materials of the chambers have been obtained from the manufacturers, and prepared as input to the PENELOPE 2003 Monte Carlo system using a computer code that includes correlated sampling and particle splitting. Values of the beam quality factors have been determined for the case of an electron reference beam. The calculated values have been compared with those in the IAEA TRS-398 dosimetry protocol and the differences analysed. The results for a NACP-02 chamber show remarkably good agreement with TRS-398 at high electron beam qualities but differ slightly at low energies. Arguments to explain the differences include questioning the undemonstrated assumption that the NACP is a 'perturbation-free' chamber even at very low electron beam energies. Results for Wellhfer PPC-40 and PPC-05 chambers cannot be compared with data from others for these chambers because no calculations or reliable experimental data exist. It has been found that the results for the PPC-40 are very close to those of a Roos chamber, but the values for the PPC-05 are considerably different from those of a Markus chamber, and rather approach those of a Roos chamber. Results for monoenergetic electrons and accelerator phase-space data have been compared to assess the need for detailed and costly simulations, finding very small differences. This questions the emphasis given in recent years to the use of 'realistic' source data for accurate electron beam dosimetry.

Sempau, Josep; Andreo, Pedro; Aldana, Judith; Mazurier, Jocelyne; Salvat, Francesc

2004-09-01

378

Correction of the Jicamarca electron-ion temperature ratio problem: Verifying the effect of electron Coulomb collisions on the incoherent scatter spectrum  

NASA Astrophysics Data System (ADS)

Ever since the first attempts to fit Jicamarca autocorrelation function (ACF) measurements in the 1970s using a full nonlinear least squares analysis, an apparent electron-ion temperature ratio below unity has been deduced for a large portion of the F region data. The cause of this unexpected and geophysically unreasonable result has been a mystery until recently, when Sulzer and Gonzlez [1999] (herein SG) explained how electron Coulomb collisions can distort, or narrow, the incoherent backscatter spectrum, and that for this narrowing to be observable two conditions must be met. First, the radar k vector must lie in a small range near perpendicular to the magnetic field, and second, the radar wavelength must be sufficiently long. Both of these conditions are true at Jicamarca. The accurate calculations from the SG theory are now available in a compact library, which we have incorporated into an incoherent scatter least squares fitting code. Using this code, we have reduced Jicamarca ACF data taken with the Faraday double-pulse mode, and find that the SG theory correctly interprets the ACF data from Jicamarca, thereby solving the longstanding Te/Ti ratio problem and thus allowing accurate electron and ion temperature measurements.

Aponte, Nstor; Sulzer, Michael P.; Gonzlez, Sixto A.

2001-11-01

379

Physical and temporal factors involved in the death of yeast at subzero temperatures.  

PubMed

The survival of yeast cells after exposure to subzero temperatures was affected by the cooling and warming velocity, temperature itself, and the physical state of the water surrounding the cells. The cells were injured only when the external medium was frozen and then only when the temperature was -10 degrees or below. Survival dropped abruptly between -10 degrees and -30 degrees regardless of whether the cells were suspended in water or 0.1 M solutions of KH(2)PO(4), NaC1, or CaC1(2). The critical temperature range of -10 degrees to -30 degrees was unrelated to the temperatures at which the suspending fluids completely solidified, these temperatures being -0.3 degrees , -11 degrees , -30 degrees , and -71 degrees for the four liquids, respectively. Survival at -30 degrees or below was greatly affected by the rate at which the cells were cooled or warmed, with higher survivals being obtained with slow cooling and with rapid warming. Length of exposure at -30 degrees was not a factor; injury was inflicted within 1 minute. The results are interpreted as indicating that death is a result of intracellular ice formation. Internal freezing is believed to occur when external ice crystals grow through aqueous channels in the cell wall or membrane and seed supercooled water in the cell interior. PMID:13768689

MAZUR, P

1961-01-01

380

Two-Dimensional Thermal Boundary Layer Corrections for Convective Heat Flux Gauges  

NASA Technical Reports Server (NTRS)

This work presents a CFD (Computational Fluid Dynamics) study of two-dimensional thermal boundary layer correction factors for convective heat flux gauges mounted in flat plate subjected to a surface temperature discontinuity with variable properties taken into account. A two-equation k - omega turbulence model is considered. Results are obtained for a wide range of Mach numbers (1 to 5), gauge radius ratio, and wall temperature discontinuity. Comparisons are made for correction factors with constant properties and variable properties. It is shown that the variable-property effects on the heat flux correction factors become significant

Kandula, Max; Haddad, George

2007-01-01

381

Temperature and risk factors for ischaemic heart disease in the Caerphilly prospective study.  

PubMed Central

OBJECTIVE--To examine the associations between air temperature and risk factors for ischaemic heart disease. METHOD--Data on risk factors are available from up to 2036 men in the Caerphilly Prospective Heart Disease Study. Daily temperatures were obtained from the Meteorological Office. Relations between these were examined by regression. RESULTS--The coldest month of the year has a mean temperature that is 16 degrees C lower than that in the warmest month. A fall in temperature of this magnitude is associated with higher blood pressures (by 3-5 mm Hg) and a lower concentration of high density lipoprotein cholesterol (by 0.08 mmol/l). The most important effects however, seem to be on the haemostatic system. Fibrinogen is 0.34 g/l higher in the coldest month than in the warmest (p < 0.001) and alpha 2 macroglobulin, a protein that inhibits fibrinolysis, is also raised. Platelet count is increased by 30% of a standard deviation and the sensitivity of platelets in whole blood to adenosine diphosphate is increased by cold. CONCLUSIONS--These effects on haemostasis, together with the effect on blood pressure, could explain a large part of the increase in ischaemic heart disease in the winter but are unlikely to explain much of the difference in mortality within different areas of England and Wales.

Eldwood, P C; Beswick, A; O'Brien, J R; Renaud, S; Fifield, R; Limb, E S; Bainton, D

1993-01-01

382

Major complications and risk factors associated with surgical correction of congenital medial patellar luxation in 124 dogs.  

PubMed

Dogs treated for congenital medial patellar luxation were reviewed for the purpose of determining the incidence of postoperative major complications requiring surgical revision and the risk factors for their occurrence. Major complications occurred in 18.5% of the patellar luxation stabilization procedures with implant associated complications being the most frequent, patellar reluxation the second, and tibial tuberosity avulsion the third most common major complication. Other complications included patellar ligament rupture and trochlear wedge displacement. When recession trochleoplasty was performed in addition to tibial tuberosity transposition, a 5.1-fold reduction in the rate of patellar reluxation was observed. Release of the cranial belly of the sartorius muscle further reduced the incidence of patellar reluxation, while patella alta (pre- or postoperative) and patellar luxation grade were not found to influence the rate of reluxation. Tibial tuberosity avulsion was 11.1-times more likely when using a single Kirschner wire to stabilize a transposition, compared with two Kirschner wires. Independent to the number of Kirschner wires used, the more caudodistally the Kirschner wires were directed, the higher the risk for tibial tuberosity avulsion. Tension bands were used in 24.4% of the transpositions with no tuberosity avulsion occurring in stifles stabilized with a tension band. Overall, grade 1 luxations had a significantly lower incidence of major complications than other grades, while body weight, age, sex, and bilateral patellar stabilization were not associated with risk of major complication development. PMID:24817090

Cashmore, R G; Havlicek, M; Perkins, N R; James, D R; Fearnside, S M; Marchevsky, A M; Black, A P

2014-07-21

383

An evaluation of milk temperature measurement for detecting oestrus in dairy cattle. I factors affecting measurement of milk temperature  

Microsoft Academic Search

The paper reports the development of an electronic system of milk temperature measurement and the results of investigations into the influence of milk yield, milk flow and ambient temperature on milk temperature. The milk and body temperatures of randomly selected multiparous Friesian cows were recorded at afternoon milkings. Temperature was measured by bead thermistors housed in perspex probes from which

D. P. Fordham; T. T. McCarthy; P. Rowlinson

1987-01-01

384

A correction factor to account for mixing in Ghyben-Herzberg and critical pumping rate approximations of seawater intrusion in coastal aquifers  

NASA Astrophysics Data System (ADS)

The classic Ghyben-Herzberg estimate of the depth of the freshwater-saltwater interface together with the Dupuit approximation is a useful tool for developing analytical solutions to many seawater intrusion problems. On the basis of these assumptions, Strack (1976) developed a single-potential theory to calculate critical pumping rates in a coastal pumping scenario. The sharp interface assumption and, in particular, this analytical solution are widely used to study seawater intrusion and the sustainable management of groundwater resources in coastal aquifers. The sharp interface assumption neglects mixing and implicitly assumes that salt water remains static. Consequently, this approximation overestimates the penetration of the saltwater front and underestimates the critical pumping rates that ensure a freshwater supply. We investigate the error introduced by adopting the sharp interface approximation, and we include the effects of dispersion on the formulation of Strack (1976). To this end, we perform numerical three-dimensional variable density flow simulations. We find that Strack's equations can be extended to the case of mixing zone if the density factor is multiplied by an empirically derived dispersion factor [1 - (?T/b')1/6], where ?T is transverse dispersivity and b' is aquifer thickness. We find that this factor can be used not only to estimate the critical pumping rate but also to correct the Ghyben-Herzberg estimate of the interface depth. Its simplicity facilitates the generalization of sharp interface analytical solutions and good predictions of seawater penetration for a broad range of conditions.

Pool, MarA.; Carrera, Jess

2011-05-01

385

Efficiency correction factors of an ACCUSCAN whole-body counter due to the biodistribution of 134Cs, 137Cs and 60Co.  

PubMed

The efficiency calibration of whole-body counters (WBCs) for monitoring of internal contaminations is usually performed with anthropomorphic physical phantoms assuming homogeneous activity distribution. Besides the inherent limitations of these phantoms in resembling the human anatomy, they do not represent a realistic activity distribution, since in real situations each incorporated radionuclide has its particular biodistribution after entering the systemic circulation. Moreover, the activity content in the different organs and tissues comprising the biokinetics is time dependent. This work aims at assessing the whole-body counting efficiency deviations arising from considering a detailed voxel phantom instead of a standard physical phantom (BOMAB) and at evaluating the effect of the anatomical differences between both phantoms. It also aims at studying the efficiency considering the biodistribution of a set of radionuclides of interest incorporated in the scope of environmental and occupational exposures (inhalation and ingestion) and at computing the time-dependent efficiency correction factors to account for the biodistribution variation over time. For the purpose, Monte Carlo (MC) simulations were performed to simulate the whole-body counting efficiencies and biokinetic models were used to estimate the radionuclides' biokinetic behaviour in the human body after intake. The comparison between the efficiencies obtained with BOMAB and the voxel phantom showed deviations between 1.8 and 11.7 %, proving the adequacy of the BOMAB for WBC calibration. The obtained correction factors show that the effect of the biodistribution in the whole-body counting efficiency is more pronounced in cases of acute activity uptake and long-term retention in certain organs than in cases of homogeneous distribution in body tissues, for which the biokinetics influence can be neglected. This work further proves the powerful combination of MC simulation methods using voxel phantoms and biokinetic models for internal dosimetry studies. PMID:23188813

Bento, J; Barros, S; Teles, P; Vaz, P; Zankl, M

2013-06-01

386

Dynamic correction for parallel conductance, GP, and gain factor, alpha, in invasive murine left ventricular volume measurements.  

PubMed

The conductance catheter technique could be improved by determining instantaneous parallel conductance (G(P)), which is known to be time varying, and by including a time-varying calibration factor in Baan's equation [alpha(t)]. We have recently proposed solutions to the problems of both time-varying G(P) and time-varying alpha, which we term "admittance" and "Wei's equation," respectively. We validate both our solutions in mice, compared with the currently accepted methods of hypertonic saline (HS) to determine G(P) and Baan's equation calibrated with both stroke volume (SV) and cuvette. We performed simultaneous echocardiography in closed-chest mice (n = 8) as a reference for left ventricular (LV) volume and demonstrate that an off-center position for the miniaturized pressure-volume (PV) catheter in the LV generates end-systolic and diastolic volumes calculated by admittance with less error (P < 0.03) (-2.49 +/- 15.33 microl error) compared with those same parameters calculated by SV calibrated conductance (35.89 +/- 73.22 microl error) and by cuvette calibrated conductance (-7.53 +/- 16.23 microl ES and -29.10 +/- 31.53 microl ED error). To utilize the admittance approach, myocardial permittivity (epsilon(m)) and conductivity (sigma(m)) were calculated in additional mice (n = 7), and those results are used in this calculation. In aortic banded mice (n = 6), increased myocardial permittivity was measured (11,844 +/- 2,700 control, 21,267 +/- 8,005 banded, P < 0.05), demonstrating that muscle properties vary with disease state. Volume error calculated with respect to echo did not significantly change in aortic banded mice (6.74 +/- 13.06 microl, P = not significant). Increased inotropy in response to intravenous dobutamine was detected with greater sensitivity with the admittance technique compared with traditional conductance [4.9 +/- 1.4 to 12.5 +/- 6.6 mmHg/microl Wei's equation (P < 0.05), 3.3 +/- 1.2 to 8.8 +/- 5.1 mmHg/microl using Baan's equation (P = not significant)]. New theory and method for instantaneous G(P) removal, as well as application of Wei's equation, are presented and validated in vivo in mice. We conclude that, for closed-chest mice, admittance (dynamic G(P)) and Wei's equation (dynamic alpha) provide more accurate volumes than traditional conductance, are more sensitive to inotropic changes, eliminate the need for hypertonic saline, and can be accurately extended to aortic banded mice. PMID:19696357

Porterfield, John E; Kottam, Anil T G; Raghavan, Karthik; Escobedo, Daniel; Jenkins, James T; Larson, Erik R; Trevio, Rodolfo J; Valvano, Jonathan W; Pearce, John A; Feldman, Marc D

2009-12-01

387

Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings  

NASA Astrophysics Data System (ADS)

The Bragg wavelength of a PMMA based fiber grating is determined by the effective core index and the grating pitch, which, in temperature sensing, depend on the thermo-optic and thermal expansion coefficients of PMMA. These two coefficients are a function of surrounding temperature and humidity. Amorphous polymers including PMMA exhibit a certain degree of anisotropic thermal expansion. The anisotropic nature of expansion mainly depends on the polymer processing history. The expansion coefficient is believed to be lower in the direction of the molecular orientation than in the direction perpendicular to the draw direction. Such anisotropic behavior of polymers can be expected in drawn PMMA based optical fiber, and will lead to a reduced thermal expansion coefficient and larger temperature sensitivity than would be the case were the fiber to be isotropic. Extensive work has been carried out to identify these factors. The temperature responses of gratings have been measured at different relative humidity. Gratings fabricated on annealed and non-annealed PMMA optical fibers are used to compare the sensitivity performance as annealing is considered to be able to mitigate the anisotropic effect in PMMA optical fiber. Furthermore an experiment has been designed to eliminate the thermal expansion contribution to the grating wavelength change, leading to increased temperature sensitivity and improved response linearity.

Zhang, Wei; Webb, David J.

2014-05-01

388

Determining desorption pre-exponential factors from temperature-programmed desorption spectra when the surface is nonuniform  

SciTech Connect

To find desorption pre-exponential factors from temperature-programmed desorption (TPD) spectra, we develop procedures using both the TPD spectra and their derivatives. First, an approximate method is derived using peak temperatures. This method is formally identical with one used for determining pre-exponential factors and desorption activation energies when desorptions are energetically uniform. The method can be used when the pre-exponential factor is constant. We next develop an iterative process that also uses peak temperatures, and again is usable when the pre-exponential factor is constant. This iterative approach should give more exact values of pre-exponential factors than the approximate approach. Using the first derivatives of TPD spectra over the entire range of temperatures leads to a second iterative process. This last procedure allows determination of energy-dependent pre-exponential factors. 8 refs., 13 figs.

Brown, L.F.; Chemburkar, R.M.

1991-03-15

389

Medium factors of electrical insulation systems in high temperature superconducting power apparatus with coil structure for equivalent ac withstand voltage test at room temperature  

Microsoft Academic Search

Equivalent insulation test voltage at room temperature of high temperature superconducting (HTS) power apparatus with coil structure for power frequency withstand voltage tests is discussed based on medium factors of insulation weak parts in electrical insulation elements of the HTS power apparatus. Uniform and non-uniform field gaps, triple junction and solid insulator surface are selected as the insulation weak parts,

M. Hara; T. Kurihara; R. Nakano; J. Suehiro

2005-01-01

390

[Temperature characteristics of huang-Ryes factor of all-trans-beta-carotene].  

PubMed

A visible absorption and Raman spectra of all-trans-beta-beta-carotene was measured in cyclohexanol solution in the temperature range from 68 degrees C to 26 degrees C. The results indicated that the visible absorption spectra are red-shifted, Raman scattering cross section increases, Huang-Ryes factor and electron-phonon coupling constants of CC bond vibration modes decreases with the temperature decreasing. The changes are interpreted using the theory of "coherent weakly damped electronic-lattice vibration model" and "effective conjugation length model". The red shift of the absorption spectra and intensity of the Raman active are attributed to the thermal conformational change-induced increase in the effective conjugation length in all-trans-beta-carotene chains. All-trans-beta-carotene has strong coherent weakly damped CC bonds vibrational properties, which lead to large Raman scattering cross section in the solvent of low temperature. The electron-phonon coupling constants with dimension are used, which can easily establish relation with the Huang-Rhys factor and calculate the electron-phonon coupling constants of CC bond vibration modes. Effective conjugation length, the pi-electron delocalization range and the Raman scattering cross section are described by the electron-phonon coupling constants. PMID:24371847

Li, Shuo; Sun, Shang; Li, Zuo-wei; Qu, Guan-nan; Liu, Tian-yuan; Sun, Cheng-lin; Fan, Li-mei

2013-09-01

391

Effects of storage time and temperature on coagulation tests and factors in fresh plasma  

PubMed Central

Coagulation tests and factors measurements have been widely applied in clinical practice. Pre-analytical conditions are very important in laboratory assessment.Here,we aim to determine the effects of storage time and temperature on activated partial thromboplastin time (APTT), fibrinogen (Fbg), prothrombin time (PT), the international normalized ratio (INR), thrombin time (TT), factor VIII activity (FVIII:C), and factor IX activity (FIX:C) in fresh plasma. Seventy-two blood samples were tested after storage for 0 (baseline), 2, 4, 6, 8, 12, and 24?h at 25C (room temperature) and 4C (refrigeration) in two centers. The mean percentage change of greater than 10% and the numbers of samples with greater than 10% percentage changes more than 25% were used to determine clinically relevant difference. We demonstrated that samples for Fbg, PT/INR, and TT could be safely stored for ?24?h; FVIII:C for ?2?h; FIX:C for ?4?h both at 4C and 25C; and APTT for ?12?h at 4C and ?8?h at 25C.

Feng, Limin; Zhao, Ying; Zhao, Hongcan; Shao, Zhexin

2014-01-01

392

Computational study of the influence of some systematic factors on the fuel temperature in a very high temperature gas-cooled reactor with prismatic fuel assemblies  

SciTech Connect

The influence of the main systematic factors of overheating (such as nonuniformity of power density and cold leaks of coolant) on the fuel temperatures in a very high temperature gas-cooled reactor NGNP (Next Generation Nuclear Plant) with prismatic fuel blocks is studied. The results of computations show a high sensitivity of the fuel temperatures to systematic factors of overheating. This circumstance indicates the necessity of high-precision three-dimensional modeling of the gas dynamics and heat transfer in the core when designing this type of reactor.

Sedov, A. A.; Frolov, A. A., E-mail: frolov@dhtp.kiae.ru [Russian Research Centre Kurchatov Institute (Russian Federation)

2011-12-15

393

Dynamic stress intensity factors of mode-I crack in high temperature superconductor  

NASA Astrophysics Data System (ADS)

The coupled magneto-mechanical model is established for the dynamic fracture problem for the high temperature superconductor (HTS). The superconductor E-J constitutive law is characterized by power law model where the critical current density is assumed to depend exponentially on the flux density. The cracked superconductor under dynamic loading are employed to investigate dynamic fracture behavior such as the variation of dynamic stress intensity factors (DSIFs) for different applied magnetic field amplitude, the thickness of HTS, and critical current density. To evaluate DSIFs for a type-II superconductor under alternating magnetic field, the flux pinning induced magnetoelasticity model proposed to evaluate DSIFs, and is implemented in conjunction with finite element method. The results show that the applied magnetic field amplitude, thickness of HTS, and critical current density are three important factors affecting the dynamic fracture behavior of the HTS.

Gao, Zhiwen; Zhou, Youhe

2013-12-01

394

Quantitative Analysis of the Head Scatter and Jaw Transmission Correction Factor for Commissioning of Enhanced Dynamic Wedge Fields Using a MapCHECK 2 Diode Array  

NASA Astrophysics Data System (ADS)

Quality assurance in radiation oncology treatment planning requires independent verification of dose to be delivered to a patient through "second check" calculations for simple plans as well as planar dose fluence measurements for more complex treatments, such as intensity modulated radiation treatments (IMRT). Discrepancies between treatment planning system (TPS) and second check calculations created a need for treatment plan verification using a two dimensional diode array for Enhanced Dynamic Wedge (EDW) fields. While these measurements met clinical standards for treatment, they revealed room for improvement in the EDW model. The purpose of this study is to analyze the head scatter and jaw transmission effects of the moving jaw in EDW fields by measuring dose profiles with a two dimensional diode array in order to minimize differences between the manufacturer provided fluence table (Golden Segmented Treatment Table) and actual machine output. The jaw transmission effect reduces the dose gradient in the wedge direction due to transmission photons adding dose to the heel region of the field. The head scatter effect also reduces the gradient in the dose profile due to decreased accelerator output at increasingly smaller field sizes caused by the moving jaw. The field size continuously decreases with jaw motion, and thus the toe region of the wedge receives less dose than anticipated due to less head scatter contribution for small field sizes. The Golden Segmented Treatment Table (GSTT) does not take these factors into account since they are specific to each individual machine. Thus, these factors need to be accounted for in the TPS to accurately model the gradient of the wedge. The TPS used in this clinic uses one correction factor (transmission factor) to account for both effects since both factors reduce the dose gradient of the wedge. Dose profile measurements were made for 5x5 cm2, 10x10 cm2, and 20x20 cm2 field sizes with open fields and 10, 15, 20, 25, 30, 45, and 60 wedges for 6 MV and 18 MV beams and compared with TPS generated profiles. The transmission factor was adjusted for the 18 MV beam to obtain a better correlation between planned and measured dose gradient by reducing the gradient of the wedge in the TPS. This correction resulted in an average and maximum pass rate improvement for patient plans at a distance to agreement of 3% 3mm of 1.07% and 3.9% respectively. The off axis ratio data in the second check calculation software was also adjusted to bring the dose agreement between the initial TPS calculation and second check calculation within clinical standards. This study demonstrated the ability to adjust the EDW gradient in a treatment planning system to improve the differences in machine output specific to each machine and the manufacturer provided GSTT.

Dickerson, Edward C.

395

Two types of phantom scatter correction factors for high-energy photons  

NASA Astrophysics Data System (ADS)

Two types of phantom scatter correction factors are introduced for high-energy photons. One is the traditional correction factor. It is produced using the primary absorbed dose under lateral CPE (charged particle equilibrium). It usually takes a non-zero value at zero-area field. The other is produced using the actual primary absorbed dose, which fails in lateral CPE when the field is small. It takes a value of zero at zero-area field. The two types of correction factors can be connected with the laterally spread primary absorbed dose (LSD).

Iwasaki, Akira

1996-12-01

396

Factor analysis for El Nio signals in sea surface temperature and precipitation  

NASA Astrophysics Data System (ADS)

Maximum likelihood factor analysis (MLFA) is applied to investigate the variables of monthly Tropical Pacific sea surface temperatures (SST) from Nio 1+2, Nio 3, Nio 3.4, and Nio 4 and precipitation over New South Wales and Queensland of eastern Australia, Kalimantan Island of Indonesia, and California and Oregon of the west coast of the United States. The monthly data used were from 1950 to 1999. The November-February SST with time leads of 0, 1, 2, and 3 months to precipitation are considered for both El Nio warm phases and non El Nio seasons. Interpretations of the factor loadings are made to diagnose relationships between the SST and precipitation variables. For El Nio signals, the rotated FA loadings can efficiently group the SST and precipitation variables with interpretable physical meanings. When the time lag is 0 or 1 month, the November-February El Nio SST explains much of the drought signals over eastern Australia and Kalimantan. However, when the time lag is 2 or 3 months, the same SST cannot adequately explain the precipitation during January-May over the two regions. Communality results of five factors for precipitation indicate nearly 100% explanation of variances for Queensland and California, but the percentages are reduced to only about 30% for Oregon and Kalimantan. Factor scores clearly identify the strongest El Nio relevant to precipitation variations. Principal component factor analysis (PCFA) is also investigated, and its results are compared with MLFA. The comparison indicates that MLFA can better group SST data relevant to precipitation. The residuals of MLFA are always smaller than the PCFA. Thus, MLFA may become a useful tool for improving potential predictability of precipitation from SST predictors.

Lee, Christine K.; Shen, Samuel S. P.; Bailey, Barbara; North, Gerald R.

2009-06-01

397

Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam.  

PubMed

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

Pham, C H; Vu, C C; Sommer, S G; Bruun, S

2014-07-01

398

Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam  

PubMed Central

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

Pham, C. H.; Vu, C. C.; Sommer, S. G.; Bruun, S.

2014-01-01

399

XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes  

SciTech Connect

We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained.

Dimakis, Nicholas [University of Texas-Pan American, Edinburg, TX 78539 (United States); Bunker, Grant [Illinois Institute of Technology, Chicago IL 60616 (United States)

2007-02-02

400

Jitter Correction  

NASA Technical Reports Server (NTRS)

Jitter_Correct.m is a MATLAB function that automatically measures and corrects inter-frame jitter in an image sequence to a user-specified precision. In addition, the algorithm dynamically adjusts the image sample size to increase the accuracy of the measurement. The Jitter_Correct.m function takes an image sequence with unknown frame-to-frame jitter and computes the translations of each frame (column and row, in pixels) relative to a chosen reference frame with sub-pixel accuracy. The translations are measured using a Cross Correlation Fourier transformation method in which the relative phase of the two transformed images is fit to a plane. The measured translations are then used to correct the inter-frame jitter of the image sequence. The function also dynamically expands the image sample size over which the cross-correlation is measured to increase the accuracy of the measurement. This increases the robustness of the measurement to variable magnitudes of inter-frame jitter

Waegell, Mordecai J.; Palacios, David M.

2011-01-01

401

High Temperature Requirement Factor A1 (HTRA1) Gene Regulates Angiogenesis through Transforming Growth Factor-? Family Member Growth Differentiation Factor 6*  

PubMed Central

Genome-wide association study (GWAS) has identified genetic variants in the promoter region of the high temperature requirement factor A1 (HTRA1) gene associated with age-related macular degeneration (AMD). As a secreted serine protease, HTRA1 has been reported to interact with members of the transforming growth factor-? (TGF-?) family and regulate their signaling pathways. Growth differentiation factor 6 (GDF6), a member of the TGF-? family, is involved in ectoderm patterning and eye development. Mutations in GDF6 have been associated with abnormal eye development that may result in microphthalmia and anophthalmia. In this report, we identified a single nucleotide polymorphism (SNP) rs6982567 A/G near the GDF6 gene that is significantly associated with AMD (p value = 3.54 10?8). We demonstrated that the GDF6 AMD risk allele (rs6982567 A) is associated with decreased expression of the GDF6 and increased expression of HTRA1. Similarly, the HTRA1 AMD risk allele (rs10490924 T) is associated with decreased GDF6 and increased HTRA1 expression. We observed decreased vascular development in the retina and significant up-regulation of GDF6 gene in the RPE layer, retinal and brain tissues in HTRA1 knock-out (htra1?/?) mice as compared with the wild-type counterparts. Furthermore, we showed enhanced SMAD signaling in htra1?/? mice. Our data suggests a critical role of HTRA1 in the regulation of angiogenesis via TGF-? signaling and identified GDF6 as a novel disease gene for AMD.

Zhang, Li; Lim, Siok Lam; Du, Hongjun; Zhang, Ming; Kozak, Igor; Hannum, Gregory; Wang, Xiaolei; Ouyang, Hong; Hughes, Guy; Zhao, Ling; Zhu, Xuemei; Lee, Clara; Su, Zhiguang; Zhou, Xinrong; Shaw, Robert; Geum, Dongho; Wei, Xinran; Zhu, Jin; Ideker, Trey; Oka, Chio; Wang, Ningli; Yang, Zhenglin; Shaw, Peter X.; Zhang, Kang

2012-01-01

402

Alveolar macrophage deficiency in osteopetrotic mice deficient in macrophage colony-stimulating factor is spontaneously corrected with age and associated with matrix metalloproteinase expression and emphysema.  

PubMed

Macrophage colony-stimulating factor (M-CSF) is one of several hematologic growth factors capable of regulating the survival, proliferation, and differentiation of macrophages, but its role in modulation of the accumulation and function of alveolar macrophages (AMs) in vivo is not well defined. Osteopetrotic (Op/Op) mice have no detectable M-CSF and show variable tissue-specific reductions in macrophage numbers. It was hypothesized that AMs would be decreased in number and have altered function in Op/Op mice because of the absence of M-CSF. Lung macrophages identified by Mac-3 staining in lung sections were decreased in number in 20-day-old Op/Op mice (P <.001) but not Op/Op mice older than 4 months (P =.68) compared with findings in age-matched littermate controls. The numbers of AMs recovered by bronchoalveolar lavage (BAL) were also reduced in young but not adult Op/Op mice compared with controls. Expression of interleukin-3 (IL-3) was increased in the lungs of Op/Op mice compared with controls as determined by quantification of IL-3 cytokine levels (P =.04), bioactivity (P =.02), and messenger RNA transcript levels. AMs of Op/Op mice spontaneously released higher levels of matrix metalloproteinases (MMPs) than AMs of controls as determined by immunohistochemical staining of AMs and zymographic assessment of BAL fluid and AM lysates. Consistent with an increased release of MMP, Op/Op mice had abnormal elastin deposition and spontaneously developed emphysema in the absence of molecular or cellular evidence of lung inflammation. These data show that the AM deficiency observed in young Op/Op mice is spontaneously corrected with age and is associated with increased lung levels of IL-3, spontaneous MMP expression by AMs, and destruction of lung tissue. PMID:11675359

Shibata, Y; Zsengeller, Z; Otake, K; Palaniyar, N; Trapnell, B C

2001-11-01

403

The effect of feed intake on ileal rate of passage and apparent amino acid digestibility determined with or without correction factors in pigs.  

PubMed

The apparent ileal digestibilities of amino acids and rate of passage were evaluated in pigs (BW = 78.3 +/- 7.4 kg) fed a semipurified diet. The pigs were fed 1.82, 2.73, or 3.65 kg DMI/d. The highest level of feed intake was considered to be ad libitum feeding. The pigs were fed according to a 3 x 3 Latin square design and were allowed to adapt to each experimental diet for 5 d. This was followed by 1 d of continuous collection of ileal digesta and a 2nd d of continuous collection separated into six 2-h postprandial time blocks. Ytterbium chloride hexahydrate was used to determine rate of passage. The ileal digestibilities of amino acids and rate of passage were unaffected (P > 0.05) by level of feed intake. The use of correction factors to more accurately express amino acid concentrations in the diet and digesta affected (P < 0.05) the apparent ileal digestibility coefficients of some amino acids. PMID:11374545

Albin, D M; Wubben, J E; Smiricky, M R; Gabert, V M

2001-05-01

404

Calculation of calibration figures and the volume correction factors for 90Y, 125I, 131I and 177Lu radionuclides based on Monte-Carlo ionization chamber simulation method  

NASA Astrophysics Data System (ADS)

Many metrology laboratories are dealing with activity measurements of different radionuclides with special interest in nuclear medicine as well as in radiopharmaceutical industry. In improving the accuracy of radionuclide activity measurements, a key role plays the calculation of calibration figures and the volume correction factors for the radionuclide under study. It is well known that the chamber calibration factors depend on the measurement geometry including the volume of the source and the type of the measurement vessel. In this work, the activity standards in the form of radioactive solutions are delivered in sealed Jena glass 5 ml FIOLAX -klar ampoule. Calculation of the calibration figures (or efficiencies) for 90Y, 125I, 131I and 177Lu radionuclides on 5 ml ampoule are presented in this paper. Additionally, their appropriate volume correction factors are determined. These calibration figures for the ISOCAL IV pressurized well re-entrant ionization chamber (IC) are pointed out based on the Monte-Carlo (MC) simulation method of such chamber using the PENELOPE-2005 MC computer simulation code. The chamber is filled with nitrogen gas pressurized to approximately 1 MPa. In determining the volume correction factors, the variation of calibration factors versus the mass of radioactive solution filling the 5 ml ampoule glass is investigated. From the point of view that impurity of 177 mLu isomer is always accompanying the 177Lu radionuclide, for making possible the correction due to presence of this impurity, the calibration factor and the volume correction factors for 177 mLu are reported as well.

Kryeziu, D.; Tschurlovits, M.; Kreuziger, M.; Maringer, F.-J.

2007-09-01

405

Temperature dependence of the electron spin $\\\\textbf{g}$ factor in CdTe and InP  

Microsoft Academic Search

Temperature dependence of the electron spin $g$ factors in bulk CdTe and InP are calculated and compared with experiment. It is assumed that the only modification of the band structure related to temperature is a dilatation change in the fundamental energy gap. The dilatation changes of fundamental gaps are calculated for both materials using available experimental data. Computations of the

Pawel Pfeffer; Wlodek Zawadzki

2011-01-01

406

Temperature-Dependence of Weibel-Palade Body Exocytosis and Cell Surface Dispersal of von Willebrand Factor and Its Propolypeptide  

Microsoft Academic Search

BackgroundWeibel-Palade bodies (WPB) are endothelial cell (EC) specific secretory organelles containing Von Willebrand factor (VWF). The temperature-dependence of Ca2+-driven WPB exocytosis is not known, although indirect evidence suggests that WPB exocytosis may occur at very low temperatures. Here we quantitatively analyse the temperature-dependence of Ca2+-driven WPB exocytosis and release of secreted VWF from the cell surface of ECs using fluorescence

Lindsay Hewlett; Gregor Zupan?i?; Gregory Mashanov; Laura Knipe; David Ogden; Matthew J. Hannah; Tom Carter

2011-01-01

407

Surface temperature-controlling factors during transaction of Mexican monsoon in the Sonoran Desert, North-West Mexico  

NASA Astrophysics Data System (ADS)

Correlation between albedo and dry land surface temperature can serve as an indicator of processes, which control the temperature. The term dry land is used in reference to arid, semi-arid and dry subhumid regions, whose humidification coefficient ranges between 0.05 and 0.65 according to United Nations Convention to combat desertification in those countries experiencing serious drought and desertification, particularly in Africa. Geneva, 1994. The three main competing factors of underlying surface temperature control are an inherent feature of dry lands: first - radiation, second - evapotranspiration, third - aerodynamic control. This study is focused on seasonal cycle of parameters, which control surface temperature in the Sonora desert (North-West Mexico). The understanding of this process is important for monitoring of desertification. This is so because in a certain year, the time span of the period, during which the radiation factor is predominant, is an important factor in the desertification process. One indirect characteristic of prevalence of the radiation factor is Normalized Difference Vegetation Index (NDVI), which is an indicator of green phytomass. The main features of the ratio between albedo and surface temperature are discussed in terms of analysis of monthly means (albedo, temperature, NDVI) in the state of Sonora (29-32N, 111-115W), in particular, within the box 30-31N, 112-113W. The analysis of synchronous time series of albedo, surface temperature and NDVI has shown that the dominating temperature-controlling factors can switch within the year in the study area. The radiation factor is dominant in dry months (April - May) and the surface temperature is negatively correlated with albedo. This can cause generation of positive albedo-precipitation feedback, which in turn contributes to the desertification process.

Tereshchenko, I.; Zolotokrilin, A.; Titkova, T.; Brito, L.; Monzon, C.

2009-12-01

408

Genetic analyses of temperature-sensitive mutations in baculovirus late expression factors.  

PubMed

Two temperature-sensitive mutants of Autographa californica nuclear polyhedrosis virus were characterized with respect to late and very late gene expression. Cells infected with ts317 or ts538 at the nonpermissive temperature revealed slightly reduced intracellular levels of late structural gene products including gp64 envelope, vp39 capsid, and p6.9 DNA binding proteins. However, with the exception of gp64, there was a dramatic reduction in extracellular levels of the structural proteins, suggesting that assembly or transport of extracellular virions was impaired. Electron microscopy confirmed the dramatic effect the mutations exhibited on viral morphogenesis. The ts538 mutation was physically mapped to the 60-65 mu region and DNA sequence analysis identified a single nucleotide alteration converting Leu to Phe in amino acid 105 of the late expression factor called lef-4. The mutation was positively correlated with the temperature-sensitive phenotype by analysis of DNA from ts+ revertants generated by marker rescue. Transient expression assays confirmed that lef-4 was required for activation of the late vp39 gene in virus infected cells. The defect in activation of the ts317 and ts538 polyhedrin genes could be overcome by coinfection with helper virus indicating that the mutations affected functions involved in activating the very late class of baculovirus genes as well. These results demonstrated a clear functional differentiation between genes regulating viral DNA replication which was normal in the mutant infected cells and those regulating late gene expression and extracellular virus production which were defective in these same infected cells. PMID:8091663

Carstens, E B; Chan, H; Yu, H; Williams, G V; Casselman, R

1994-10-01

409

Adsorbate migration effects on continuous and discontinuous temperature-dependent transitions in the quality factors of graphene nanoresonators.  

PubMed

We perform classical molecular dynamics simulation to investigate the mechanisms underpinning the unresolved, experimentally observed temperature-dependent scaling transition in the quality factors of graphene nanomechanical resonators (GNMRs). Our simulations reveal that the mechanism underlying this temperature scaling phenomenon is the out-of-plane migration of adsorbates on GNMRs. Specifically, the migrating adsorbate undergoes frequent collisions with the GNMR, which strongly influences the resulting mechanical oscillation, and thus the quality factors. We also predict a discontinuous transition in the quality factor at a lower critical temperature, which results from the in-plane migration of the adsorbate. Overall, our work clearly demonstrates the strong effect of adsorbate migration on the quality factors of GNMRs. PMID:24334407

Jiang, Jin-Wu; Wang, Bing-Shen; Park, Harold S; Rabczuk, Timon

2014-01-17

410

Rockslides in a changing climate: evaluating rainfall and temperature as triggering factors in southwestern Norway  

NASA Astrophysics Data System (ADS)

Climatic conditions such as rainfall and temperature often play an important role in the triggering of geohazards, such as landslides, rockfalls and snow avalanches. This is especially true in coastal, mountainous areas such as Norway. In the last 150 years, geohazards have resulted in over 2,000 casualties in Norway, making it an important area of study. With recent climate research indicating significant climate change in northern regions, it has become apparent that a better understanding of the link between clim