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1

Determining the temporal variability in atmospheric temperature profiles measured using radiosondes and assessment of correction factors for different launch schedules  

NASA Astrophysics Data System (ADS)

Radiosondes provide one of the primary sources of upper troposphere and stratosphere temperature data for numerical weather prediction, the assessment of long-term trends in atmospheric temperature, study of atmospheric processes and provide intercomparison data for other temperature sensors, e.g. satellites. When intercomparing different temperature profiles it is important to include the effect of temporal mismatch between the measurements. To help quantify this uncertainty the atmospheric temperature variation through the day needs to be assessed, so that a correction and uncertainty for time difference can be calculated. Temperature data from an intensive radiosonde campaign, at Manus Island in Papua New Guinea, were analysed to calculate the hourly rate of change in temperature at different altitudes and provide recommendations and correction factors for different launch schedules. Using these results, three additional longer term data sets were analysed (Lindenberg 1999 to 2008; Lindenberg 2009 to 2012; and Southern Great Plains 2006 to 2012) to assess the diurnal variability of temperature as a function of altitude, time of day and season of the year. This provides the appropriate estimation of temperature differences for given temporal separation and the uncertainty associated with them. A general observation was that 10 or more repeat measurements would be required to get a standard error of the mean of less than 0.1 K per hour of temporal mismatch.

Butterfield, D.; Gardiner, T.

2015-01-01

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

An experimental and computational investigation of the standard temperature-pressure correction factor for ion chambers in kilovoltage x rays  

SciTech Connect

For ion chambers with cavities open to the surrounding atmosphere, the response measured at a given temperature and pressure must be corrected using the standard temperature-pressure correction factor (P{sub TP}). A previous paper based solely on Monte Carlo simulations [D. J. La Russa and D. W. O. Rogers, Med. Phys. 33, 4590-4599 (2006)] pointed out the shortcomings of the P{sub TP} correction factor when used to correct the response of non-air-equivalent chambers for low-energy x-ray beams. This work presents the results of several experiments that corroborate these calculations for a number of ion chambers. Monte Carlo simulations of the experimental setup revealed additional insight into the various factors affecting the extent of the breakdown of P{sub TP}, including the effect of impurities and the sensitivity to chamber dimensions. For an unfiltered 60 kV beam, the P{sub TP}-corrected response of an NE 2571 ion chamber measured at 0.7 atm was 2.5% below the response measured at reference conditions. In general, Monte Carlo simulations of the experimental setup using EGSnrc were within 0.5% of measured values. EGSnrc-calculated values of air kerma calibration coefficients (N{sub K}) at low x-ray energies are also provided as a means of estimating the level of impurities in the chambers investigated. Calculated values of N{sub K} normalized to the value measured for a 250 kV beam were obtained for three chambers and were within 1% of experiment with one exception, the Exradin A12 in a 50 kV beam.

La Russa, Daniel J.; McEwen, Malcolm; Rogers, D. W. O. [Carleton Laboratory for Radiotherapy Physics, Ottawa Carleton Institute of Physics, Carleton University, Ottawa, ON K1S 5B6 (Canada); Ionizing Radiation Standards, National Research Council of Canada, M-35 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Carleton Laboratory for Radiotherapy Physics, Ottawa Carleton Institute of Physics, Carleton University, Ottawa, ON K1S 5B6 (Canada)

2007-12-15

4

Optimizing Power Factor Correction  

E-print Network

the capacity or demand charge and the energy charge. Increases of the annual electric cost as the power factor decreases are shown in Table I under the assumptions that each month of the year is identical, the metered KW demand is 1,000 kW... .. 300,000 kWh/mo Meter Demand = 1,000 kW Yearly Yearly Yearly Penalty for Billing Capacity Energy Total Low Power Power Capacity Charge Charge Cost Factor Factor kVA $/yr ---- ~~ -1!.E 1.00 1,000 46,920 94,800 186,868 0.96 1,042 48,795 95...

Phillips, R. K.; Burmeister, L. C.

5

Theoretical full power correction factors as related to changes in ambient temperature, pressure and absolute humidity for aircraft turbine engines  

E-print Network

and of the ambient atmospheric temperature. 61 SYMBOLS, SUBSCRIPTS AND UNITS ~Smb o 1, Definition Temperature p = Pres sure PR = Pressure Ratio h . = Enthalpy m = Mass flow rate s = Entropy v = Specific volume Units. Kelvin ('K) ' Rankine ('R) Fahrenheit... - ? ) ? ? (1- ? ) v 2 3 v v v YT where R is the universal constant for the gas in question, 15 T is the temperature level in degrees Rankine, 3 v is the specific volume in ft /pmole. A , B , C , a, b are constants depending on the substance 0 0 0 we...

Raphael, Michel Antoun

1969-01-01

6

Correcting temperature-sensitive protein folding defects.  

PubMed Central

Recently, we found that different low molecular weight compounds, all known to stabilize proteins in their native conformation, are effective in correcting the temperature-sensitive protein folding defect associated with the deltaF508 cystic fibrosis transmembrane regulator (CFTR) protein. Here we examined whether the folding of other proteins which exhibit temperature-sensitive folding defects also could be corrected via a similar strategy. Cell lines expressing temperature-sensitive mutants of the tumor suppressor protein p53, the viral oncogene protein pp60src, or a ubiquitin activating enzyme E1, were incubated at the nonpermissive temperature (39.5 degrees C) in the presence of glycerol, trimethylamine N-oxide or deuterated water. In each case, the cells exhibited phenotypes similar to those observed when the cells were incubated at the permissive temperature (32.5 degrees C), indicative that the particular protein folding defect had been corrected. These observations, coupled with our earlier work and much older studies in yeast and bacteria, indicate that protein stabilizing agents are effective in vivo for correcting protein folding abnormalities. We suggest that this type of approach may prove to be useful for correcting certain protein folding abnormalities associated with human diseases. PMID:9077553

Brown, C R; Hong-Brown, L Q; Welch, W J

1997-01-01

7

Factors of Addiction: New Jersey Correctional Population  

ERIC Educational Resources Information Center

Most state inmates incarcerated under the jurisdiction of the New Jersey Department of Corrections are driven to crimes by drug abuse. Understanding the factors contributing to addiction is the first step in developing strategies for successful inmate reintegration. This study presents an analysis of inmate addiction and factor association using…

Wojtowicz, James P.; Liu, Tongyin; Hedgpeth, G. Wayne

2007-01-01

8

QED radiative corrections to impact factors  

SciTech Connect

We consider radiative corrections to the electron and photon impact factors. The generalized eikonal representation for the e{sup +}e{sup -} scattering amplitude at high energies and fixed momentum transfers is violated by nonplanar diagrams. An additional contribution to the two-loop approximation appears from the Bethe-Heitler mechanism of fermion pair production with the identity of the fermions in the final state taken into account. The violation of the generalized eikonal representation is also related to the charge parity conservation in QED. A one-loop correction to the photon impact factor for small virtualities of the exchanged photon is obtained using the known results for the cross section of the e{sup +}e{sup -} production during photon-nuclei interactions.

Kuraev, E.A. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Researches, Dubna, Moscow oblast, 141980 (Russian Federation); Lipatov, L.N. [St. Petersburg Nuclear Physics Institute, Gatchina, Leningrad oblast, 188350 (Russian Federation); Shishkina, T.V. [Belarus State University, Minsk, 220040 (Belarus)

2001-02-01

9

Hyponatremia: evaluating the correction factor for hyperglycemia  

Microsoft Academic Search

PURPOSE: There are no controlled experimental data that assess the accuracy of the commonly used correction factor of a 1.6 meq\\/L decrease in serum sodium concentration for every 100 mg\\/dL increase in plasma glucose concentration. The purpose of this study was to evaluate experimentally the hyponatremic response to acute hyperglycemia.SUBJECTS AND METHODS: Somatostatin was infused to block endogenous insulin secretion

Teresa A. Hillier; Robert D. Abbott; Eugene J. Barrett

1999-01-01

10

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

11

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

12

Possible resolution of the Casimir force finite temperature correction "controversies"  

E-print Network

By considering the effect of diffusion on the external electric field response of charge carriers in metals and semiconductors, it is shown that the finite temperature correction proposed Bostrom and Sernelius requires substantial modification, and there is no large correction as suggested for good conductors. The apparent violation of the Third Law of Thermodynamics of the various proposed temperature corrections to the Casimir force is also resolved. Finally, the effect of Debye screening on electrostatic calibrations between pure germanium surfaces is calculated

Steve K. Lamoreaux

2008-01-08

13

Fermilab's Booster Correction Element Power Supply Silicon Temperature Rise  

SciTech Connect

Fermilab is in the process of upgrading its Booster Correction Element System to include full field correction element magnets to correct position and chromaticity throughout the booster cycle. For good reliability of the switchmode power supplies designed to power the magnets, it is important to limit both the maximum temperature and the repetitive temperature cycling of the silicon junctions of the switching elements. We will describe how we measured these parameters and the results of our measurements.

Krafczyk, G.; Jensen, C.; Pfeffer, H.; Warchol, G.; /Fermilab

2009-05-01

14

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

15

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

16

Well correction factors for three-dimensional reservoir simulation  

E-print Network

WELL CORRECTION FACTORS POR THREE-DIMENSIONAL RESERVOIR SIMULATION A Thesis by PAUL ALBERT FJERSTAD Submitted to the Graduate College of Texas A&M University' in partial fulfillment for the requirements for the degree of MASTER OP SCIENCE... August 1985 Major Subject: Petroleum Engi. nearing WELL CORRECTION FACTORS FOR THREE-DIMENSIONAL RESERVOIR SIMULATION A Thesis by PAUL ALBERT FJERSTAD Approved as to style and content by: W. . Von Gonten (Chai n of Committee) R. A. Wattenbarge...

Fjerstad, Paul Albert

1985-01-01

17

Second Order Corrections to QED Coupling at Low Temperature  

E-print Network

We calculate the second order corrections to vacuum polarization tensor of photons at low temperatures, i.e; T $\\le 10^{10}$ K ($T temperatures below the electron mass that is $Ttemperatures has explicitly been checked. The electromagnetic properties of such a thermal medium are modified. Parameters like electric permittivity and magnetic permeability of such a medium are no more constant and become functions of temperature.

Samina S. Masood; Mahnaz Q. Haseeb

2008-07-29

18

Application of bottom-hole temperature corrections in geothermal studies  

SciTech Connect

Bottom-hole temperature (BHT) data measured in oil and gas wells constitute a large, low-quality set of temperature observations commonly used in geothermal studies. Raw BHT data are, on the average, cooler than true formation temperatures. To estimate true formation temperatures, corrections must be applied. Empirical BHT corrections may be applied to BHT data for which only depths of measurement are known, but may not be valid outside of the area for which they are calibrated. If multiple BHT measurements from successive logging runs are available, the Horner plot correction procedure can be used. The accuracy of the Horner plot is limited by simplifying assumptions made in its derivation, and by the common lack of information on parameters such as duration of mud circulation. More detailed and complete treatments provide insight into the borehole equilibration process, but their application is similarly limited by a common lack of data regarding borehole thermal properties. A new type of empirical correction procedure may be derived in some areas and allows a correction to be made for BHTs for which only a depth and time of measurement are known.

Deming, D. (Dept. of Geology and Geophysics, Louisiana State Univ., Baton Rouge, LA (US))

1989-01-01

19

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. PMID:24787639

Sun, Jian; Zhao, Kai; Jiang, Tao

2014-01-01

20

A multipoint correction method for environmental temperature changes in airborne double-antenna microwave radiometers.  

PubMed

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. PMID:24787639

Sun, Jian; Zhao, Kai; Jiang, Tao

2014-01-01

21

Literature Review Report 2 Overview of Power Factor Correction  

Microsoft Academic Search

In this report, we will review the fundamentals of power factor correction. We will also introduce a power factor corrector using the most popular topology, the boost PFC pre-regulator. Then a simulation model of a boost PFC pre-regulator by Dranga and Tse(3), together with some experimental verification result will also be presented.

Grace Chu

2006-01-01

22

Correction of Temperatures of Air-Cooled Engine Cylinders for Variation in Engine and Cooling Conditions  

NASA Technical Reports Server (NTRS)

Factors are obtained from semiempirical equations for correcting engine-cylinder temperatures for variation in important engine and cooling conditions. The variation of engine temperatures with atmospheric temperature is treated in detail, and correction factors are obtained for various flight and test conditions, such as climb at constant indicated air speed, level flight, ground running, take-off, constant speed of cooling air, and constant mass flow of cooling air. Seven conventional air-cooled engine cylinders enclosed in jackets and cooled by a blower were tested to determine the effect of cooling-air temperature and carburetor-air temperature on cylinder temperatures. The cooling air temperature was varied from approximately 80 degrees F. to 230 degrees F. and the carburetor-air temperature from approximately 40 degrees F. to 160 degrees F. Tests were made over a large range of engine speeds, brake mean effective pressures, and pressure drops across the cylinder. The correction factors obtained experimentally are compared with those obtained from the semiempirical equations and a fair agreement is noted.

Schey, Oscar W; Pinkel, Benjamin; Ellerbrock, Herman H , Jr

1939-01-01

23

Correction of particulate matter concentrations to reference temperature and pressure conditions  

SciTech Connect

The 1997 revisions to the particulate matter NAAQS included changes in the reporting method of observed concentrations. Pollutant concentration data contained in EPA`s Aerometric Information Retrieval System (AIRS) prior to the 1997 revisions had been required to be reported in units corrected to standard temperature and pressure (25{degree} C, 760 mm Hg). This requirement was removed so that, in the new regulations, the particulate matter data will be reported to AIRS at local temperature and pressure. This work analyzes the impact of this revision to the spatial and temporal pattern of PM10 concentrations. The influence of pressure and temperature individually on the correction of US PM10 concentrations was first examined over a seasonal time scale. The two correction factors were then combined to produce a total correction factor and, subsequently, uncorrected PM10 concentration maps at local conditions were derived. The temperature correction was further inspected for purposes of determining differences between quarterly and monthly aggregations. Particulate matter concentrations expressed in terms of local pressure may be between 10 and 25 percent lower than those reported at standard pressure with the largest decreases occurring in the high elevation areas of the western US The temperature correction is most influential in the Northeast and Upper Midwest during the cold months with PM concentrations up to 10% higher than those reported at standard temperature. Combing the temperature and pressure corrections results in PM10 increases up to 5% in the Northeast and Upper Midwest during the winter and decreases up to 25% in the West, with the summer months experiencing greater decreases than the winter.

Falke, S.R.; Husar, R.B. [Washington Univ., St. Louis, MO (United States). Center for Air Pollution Impact and Trend Analysis

1998-12-31

24

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.

25

Extended Source Size Correction Factor in Antenna Gain Measurements  

NASA Astrophysics Data System (ADS)

In this paper we present improved formulations for the extended source size correction factors that are widely utilized in circular aperture reflector antenna gain measurements. Extended radio sources having an angular size that is comparable or larger than the FWHP antenna beamwidth are often used to determine the directivity of the antenna aperture. The resulting directivity measurements must be corrected to account for the convolution of the extended source angular size with the antenna's far field pattern beamwidth. Two kinds of extended radio sources, having either uniform or Gaussian brightness distributions over the source disk, as well as three kinds of the antenna aperture distributions: "Polynomial-on-Pedestal", Gaussian, and Taylor have been considered. The existing approximate formulae for the extended source size correction factor are examined and compared to the improved formulations.

Solovey, A.; Mittra, R.

2008-10-01

26

Correcting OATS antenna factors for small fully anechoic chambers  

Microsoft Academic Search

Antenna correction factors have been experimentally determined inside a 3 m fully anechoic chamber. In the frequency range of 30-1000 MHz deviations to the manufacturer data, taken from a 10 m OATS, of up to 5 dB have been found in the low frequency range. In the high frequency range the calibration for horizontal polarization was strongly affected, in a

Diethard Hansen; Detlef Ristau; Peter Lilienkamp

2000-01-01

27

Improved induction-heating inverter with power factor correction  

Microsoft Academic Search

An inverter aimed at induction heating applications is presented. It features power factor correction and fast response to sudden changes in the load, while providing the capability to vary the power supplied to the load. Power variation is achieved by means of pulse density modulation using variable-length sequences; thus allowing a high number of power levels to be achieved. The

Hugo Calleja; R. Ordonez

1999-01-01

28

Solar Correction Factors of Building Envelope in Tebei  

E-print Network

Tebei has very rich solar energy in China and needs heating in winter,but the present energy building design code has no solar correction factor for the overall heat transfer coefficient of building envelope for Tebei. Based on the typical year...

Wang, D.; Tang, M.

2006-01-01

29

Eucken correction in high-temperature gases with electronic excitation  

SciTech Connect

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., E-mail: elena-kustova@mail.ru; Mekhonoshina, M. A. [Saint Petersburg State University, 28 Universitetsky pr., 198504 Saint Petersburg (Russian Federation)] [Saint Petersburg State University, 28 Universitetsky pr., 198504 Saint Petersburg (Russian Federation)

2014-05-14

30

Cell asymmetry correction for temperature modulated differential scanning calorimetry  

SciTech Connect

The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter, which is important for temperature-modulated DSC. Heat capacities for sapphire-filled and empty aluminium calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, positive and negative signs of asymmetry were explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 18{degree} depending on asymmetry sign. Once the asymmetry sign is determined, the asymmetry correction for modulated DSC can be made.

Ishikiriyama, K.; Wunderlich, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)

1996-12-31

31

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

32

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

33

Correction for PMT temperature dependence of the LHCf calorimeters  

NASA Astrophysics Data System (ADS)

LHCf is an experiment to measure the very forward production of particles at LHC in order to calibrate the hadronic interaction models used to simulate cosmic-ray air showers. The results obtained from ?s = 7 TeV proton-proton collisions have large systematic errors resulting from the energy scale shift of the reconstructed ?0 mass. It was found that one of the major sources of this shift is the temperature dependence of the PMT response used in the LHCf detectors. In order to correct the variation of the PMT gain by temperature, two types of temperature variation were considered. As a result, systematic errors resulting from the energy scale of Arm2 was improved by 30 %.

Matsubayashi, Eri; LHCf collaboration

2015-02-01

34

Replacement correction factors for cylindrical ion chambers in electron beams  

SciTech Connect

Purpose: In the TG-21 dosimetry protocol, for cylindrical chambers in electron beams the replacement correction factor P{sub repl} (or the product p{sub dis}p{sub cav} in the IAEA's notation), was conceptually separated into two components: the gradient correction (P{sub gr}) accounting for the effective point of measurement and the fluence correction (P{sub fl}) dealing with the change in the electron fluence spectrum. At the depth of maximum dose (d{sub max}), P{sub gr} is taken as 1. There are experimental data available at d{sub max} for the values of P{sub fl} (or P{sub repl}). In the TG-51 dosimetry protocol, the calibration is at the reference depth d{sub ref}=0.6R{sub 50}-0.1 (cm) where P{sub gr} is required for cylindrical chambers and P{sub fl} is unknown and so the measured values at d{sub max} are used with the corresponding mean electron energy at d{sub ref}. Monte Carlo simulations are employed in this study to investigate the replacement correction factors for cylindrical chambers in electron beams. Methods: Using previously established Monte Carlo calculation methods, the values of P{sub repl} and P{sub fl} are calculated with high statistical precision (<0.1%) for cylindrical cavities of a variety of diameters and lengths in a water phantom irradiated by various electron beams. The values of P{sub gr} as defined in the TG-51 dosimetry protocol are also calculated. Results: The calculated values of the fluence correction factors P{sub fl} are in good agreement with the measured values when the wall correction factors are taken into account for the plane-parallel chambers used in the measurements. An empirical formula for P{sub fl} for cylindrical chambers at d{sub ref} in electron beams is derived as a function of the chamber radius and the beam quality specifier R{sub 50}. Conclusions: The mean electron energy at depth is a good beam quality specifier for P{sub fl}. Thus TG-51's adoption of P{sub fl} at d{sub max} with the same mean electron energy for use at d{sub ref} is proven to be accurate. The values of P{sub gr} for a Farmer-type chamber as defined in the TG-51 dosimetry protocol may be wrong by 0.3% for high-energy electron beams and by more than 1% for low-energy electron beams.

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

2009-10-15

35

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; Fernández-Varea, José M; Izewska, Joanna

2010-03-21

36

Temperature corrections in the Priestley-Taylor equation of evaporation  

NASA Astrophysics Data System (ADS)

The Priestley-Taylor equation (PTE) is frequently applied in actual areal evapotranspiration (ET) estimation methods for obtaining the maximum daily rate of evaporation with data from sub-humid conditions. Since PTE was parameterized under humid conditions, a temperature correction is necessary to avoid overestimation of the maximum rate of ET. Wet-environment surface temperature (Tws), a proxy of the wet-environment air temperature (Twa), is estimated by the Szilagyi-Jozsa (SJ) approach as well as by a re-parameterized version of Monteith. The latter yields higher values but typically within 1 °C of the former. Tested by daily FLUXNET data, the estimates are only mildly sensitive to the mean daily wind velocity which thus can be replaced by a region-representative monthly average. From long-term simplified water-balances - plus monthly Moderate Resolution Imaging Spectroradiometer (MODIS) and ERA-Interim re-analysis data - the re-parameterized Monteith method appears to yield more accurate Tws estimates, while the PTE performs better with the SJ provided Tws values since they are closer to Twa, the PTE expects. Both methods require net radiation, air temperature, humidity and monthly mean wind velocity values plus ground heat fluxes when employed on a daily basis.

Szilagyi, Jozsef

2014-11-01

37

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

38

Shear-layer correction after Amiet under consideration of additional temperature gradient. Working diagrams for correction of signals  

NASA Technical Reports Server (NTRS)

Amiet's correction scheme for sound wave transmission through shear-layers is extended to incorporate the additional effects of different temperatures in the flow-field in the surrounding medium at rest. Within a parameter-regime typical for acoustic measurements in wind tunnels amplitude- and angle-correction is calculated and plotted systematically to provide a data base for the test engineer.

Dobrzynski, W.

1984-01-01

39

Finite-temperature electron correlations in the framework of a dynamic local-field correction  

SciTech Connect

The quantum-mechanical version of the Singwi-Tosi-Land-Sjoelander (STLS) approximation is applied to finite temperatures. This approximation has two main advantages. First, it includes a dynamic local-field correction and second, it gives positive values for the pair-distribution function in the short-range region at zero temperature. This is even valid for rather low densities. After a description of the numerical difficulties arising with the use of a dynamic approximation, the results for the static-structure factor and the pair-distribution function are discussed thoroughly. Detailed work is performed on the static part of the local-field correction, with special emphasis put on the investigation of its structure. A peak is found at a wave vector [ital q][approx]2.8 (in units of the Fermi wave vector) for small temperatures, which tends towards higher values of [ital q] with increasing temperature. This peak causes an attractive particle-hole interaction in a certain [ital q] region and thus gives rise to the appearance of a charge-density wave. A parametric description is given for the static local-field correction in order to simplify further applications. Furthermore, the exchange-and-correlation free energy is considered. The results are compared with the STLS results and with the modified convolution approach.

Schweng, H.K.; Boehm, H.M. (Institut fuer Theoretische Physik, Johannes Kepler Universitaet Linz, A-4040 Linz-Auhof (Austria))

1993-07-15

40

Corrections to statistical modeling of spectra for plasmas at moderate or low temperatures  

NASA Astrophysics Data System (ADS)

For plasmas in LTE at moderate or low temperatures (1-50 eV), the statistical approach for calculating emission or absorption spectra may become inaccurate and need improvement to account for the Boltzmann factor in the population of the levels. In this work, corrections to the transition rates are computed by using the moments of emission or absorption zones, which represent the set of levels within a configuration that provide the dominant part of the emissivity (or opacity). Partition functions are also improved by using high-order moments of level energy distributions. Corrections to the statistical models are derived in a non-relativistic framework as a function of these moments, which can be deduced from already published formulas. Numerical comparisons of detailed line-by-line and statistical calculations are presented that clearly illustrate the importance of correcting the models at low temperatures. Thus, these corrections are of great interest for applications such as Warm Dense Matter, LTE photo-absorption experiments where the targets are heated to ˜ Te = 20 eV and astrophysical plasmas.

Gilleron, F.; Pain, J.-C.; Porcherot, Q.; Bauche, J.; Bauche-Arnoult, C.

2011-12-01

41

Finite volume form factors and correlation functions at finite temperature  

E-print Network

In this thesis we investigate finite size effects in 1+1 dimensional integrable QFT. In particular we consider matrix elements of local operators (finite volume form factors) and vacuum expectation values and correlation functions at finite temperature. In the first part of the thesis we give a complete description of the finite volume form factors in terms of the infinite volume form factors (solutions of the bootstrap program) and the S-matrix of the theory. The calculations are correct to all orders in the inverse of the volume, only exponentially decaying (residual) finite size effects are neglected. We also consider matrix elements with disconnected pieces and determine the general rule for evaluating such contributions in a finite volume. The analytic results are tested against numerical data obtained by the truncated conformal space approach in the Lee-Yang model and the Ising model in a magnetic field. In a separate section we also evaluate the leading exponential correction (the $\\mu$-term) associated to multi-particle energies and matrix elements. In the second part of the thesis we show that finite volume factors can be used to derive a systematic low-temperature expansion for correlation functions at finite temperature. In the case of vacuum expectation values the series is worked out up to the third non-trivial order and a complete agreement with the LeClair-Mussardo formula is observed. A preliminary treatment of the two-point function is also given by considering the first nontrivial contributions.

Balázs Pozsgay

2009-07-24

42

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

43

The perturbation correction factors for cylindrical ionization chambers in high-energy photon beams  

Microsoft Academic Search

In this study, we calculated perturbation correction factors for cylindrical ionization chambers in high-energy photon beams\\u000a by using Monte Carlo simulations. We modeled four Farmer-type cylindrical chambers with the EGSnrc\\/Cavity code and calculated\\u000a the cavity or electron fluence correction factor, P\\u000a cav, the displacement correction factor, P\\u000a dis, the wall correction factor, P\\u000a wall, the stem correction factor, P\\u000a stem,

Fumiaki Yoshiyama; Fujio Araki; Takeshi Ono

2010-01-01

44

Corrected long wave radiation budget of the Earth, discussion of solar radiation budget and simulations of Earth's radiative temperature as a function of carbon dioxide quantity and other factors  

Microsoft Academic Search

Summary On the base of articles Zastawny (2004) and Zastawny (2006), a corrected, long wave radiation budget of the Earth is presented. Considering the diffusive character of long wave radiation transport, the large difference between the effective coefficient of absorption of long wave radiation calculated in first work from the radiation budget, and the one calculated in the second work

Andrzej Zastawny

45

Curved tube correction factors for indirect measurements with a radiation thermometer.  

PubMed

To measure surface temperature, a radiation guide in the form of a curved tube with a specular wall is used to couple thermal energy between a target surface and a radiometer. The relationship between the radiometer output and the target temperature depends on a correction factor, CF, which is a function of the tube temperature and another factor CFS. The term CFS, determined by the shape and reflectivity of the tube, is computed by a ray-trace technique. Calculations show how the factor CFS depends both on the ratio of tube length-to-diameter and length-to-bend radius. A particular gold-plated tube in conjunction with a radiometer having a narrowband filter at 7.9 microm is used to verify the relationship between surface temperature and radiometer output. Surface temperatures in the 0-100 degrees C range are measured for various fixed wall temperatures. There is good agreement between the measured and the calculated values. PMID:20309318

Kotlarchyk, M; Po, H

1981-04-15

46

An Egsnrc investigation of the P(TP) correction factor for ion chambers in kilovoltage X rays.  

PubMed

As part of the standard practice for obtaining consistent ion chamber measurements with cavities open to the surrounding atmosphere, the raw measured response is corrected to the response at a reference temperature and pressure using the standard temperature-pressure correction factor (P(TP)). In this study, the EGSnrc Monte Carlo code was used to investigate the validity of the P(TP) correction factor for kilovoltage x rays incident on various geometrically distinct ion chambers. The calculated P(TP)-corrected chamber response deviated by over 2% relative to expected values for a 40 kV spectrum incident on a graphite thimble chamber at an air density typical of Mexico City. The relative deviation from the expected response was much worse for a large spherical graphite chamber, exceeding 16% at an air density of 0.6 kg/m3 (approximately 0.5 atm at 22 degrees C) for the same beam energy. The breakdown of the P(TP) correction factor was also observed for a 26 kV mammography spectrum incident on two mammography chambers. For 60Co beams, the P(TP) correction factor behaved as expected. For day-to-day variations in pressure, only a negligible of the P(TP) correction factor was observed with low x-ray energies. Factors contributing to the breakdown of the P(TP) correction factor at low x-ray energies and large pressure variations, such as the range of electrons, the material of the wall, the chamber dimensions and air-photon interactions, are discussed in depth. PMID:17278811

La Russa, Daniel J; Rogers, D W O

2006-12-01

47

Variation in barometric pressure in Melbourne does not significantly affect the BTPS correction factor.  

PubMed

The conventional BTPS (body temperature and pressure, saturated with water vapour) correction factor varies with ambient barometric pressure (P(B)) and many lung function laboratories measure P(B) daily. The aim was to investigate whether a fixed value for P(B) could replace daily measurements. P(B) was measured daily over a 12-month period. The highest and lowest values in Melbourne in the last century were also recorded from data published by the Bureau of Meteorology. Using these P(B) values, the BTPS factor was determined for a range of spirometer temperatures and compared to the BTPS factors obtained using a fixed ambient pressure of 101.3 kPa. The mean (SD) P(B) measured over the 12-month period was 102.2 kPa (0.64) with a range of 99.9-103.6 kPa. The level of disagreement between the BTPS factor calculated using a P(B) of 101.3 kPa instead of the measured value was greater at lower temperatures. Over the extremes of P(B) during the last century (98.0-104.3 kPa) the use of a standard pressure (101.3 kPa) produced an error in the BTPS factor of correction factor and a fixed value, such as 101.3 kPa at sea level, can be used with little error. PMID:15363017

Johns, David P; Hartley, M Faizel; Burns, Graham; Thompson, Bruce R

2004-08-01

48

A Generalized Finite Source Calibration Factor: A Natural Improvement to the Finite Source Correction Factor for Uranium Holdup Measurements  

SciTech Connect

This paper proposes refinements to the finite source correction factor used in holdup measurements. Specifically it focuses on a more general method to estimate the average detector response for a finite source. This proposed method for the average detector response is based directly on the Generalized Geometry Holdup (GGH) assay method. First, the finite source correction factor as originally proposed is reviewed in this paper. Following this review the GGH assay method is described. Lastly, a new finite area calibration factor based on GGH is then proposed for finite point and line sources. As an alternative to the direct use of the finite arca calibration factor, finite source correction factors are also derived from this calibration factor. This new correction factor can be used in a manner similar to the finite source correction factor as currently implemented.

Gunn, C.A.; Oberer, R.B.; chiang, L.G.; Ceo, R.N.

2003-01-28

49

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

50

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

Code of Federal Regulations, 2014 CFR

...2014-07-01 false NOX intake-air humidity and temperature corrections...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Requirements § 1065.670 NOX intake-air humidity and temperature...

2014-07-01

51

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 false NOX intake-air humidity and temperature corrections...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Requirements § 1065.670 NOX intake-air humidity and temperature...

2011-07-01

52

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false NOX intake-air humidity and temperature corrections...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Requirements § 1065.670 NOX intake-air humidity and temperature...

2013-07-01

53

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 false NOX intake-air humidity and temperature corrections...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Requirements § 1065.670 NOX intake-air humidity and temperature...

2012-07-01

54

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 false NOX intake-air humidity and temperature corrections...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Requirements § 1065.670 NOX intake-air humidity and temperature...

2010-07-01

55

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

56

Quantum Critical Scaling and Temperature-Dependent Logarithmic Corrections in the Spin-Half Heisenberg Chain  

SciTech Connect

Low temperature dynamics of the S=(1)/(2) Heisenberg chain is studied via a simple ansatz generalizing the conformal mapping and analytic continuation procedures to correlation functions with multiplicative logarithmic factors. Closed form expressions for the dynamic susceptibility and the NMR relaxation rates 1/T{sub 1} and 1/T{sub 2G} are obtained, and are argued to improve the agreement with recent experiments. Scaling in q/T and {omega}/T are violated due to these logarithmic terms. Numerical results show that the logarithmic corrections are very robust. While not yet in the asymptotic low temperature regime, they provide striking qualitative confirmation of the theoretical results. {copyright} {ital 1997} {ital The American Physical Society}

Starykh, O.; Singh, R. [Department of Physics, University of California, Davis, California 95616 (United States)] [Department of Physics, University of California, Davis, California 95616 (United States); Sandvik, A. [National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32306 (United States)] [National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32306 (United States)

1997-01-01

57

Development of temperature correction equations for bioelectrical impedance analysis models for brook trout Salvelinus fontinalis.  

PubMed

The objective of this study was to establish the relationships between bioelectrical impedance analysis (BIA) measures (resistance and reactance) and temperature and to determine if corrections improve BIA models for brook trout Salvelinus fontinalis when used over a wide range of temperatures. Both resistance and reactance significantly decreased as temperature increased. Application of temperature corrections to BIA models attempting to predict per cent dry mass reduced root-mean-squared error by an average of 32%. Researchers taking BIA measures on fishes in the field where temperature varies will need to correct resistance and reactance to the temperature at which the BIA model was developed for successful predictions of per cent dry mass to be possible. This study presents a clear description of methods that can be used to developed temperature correction equations so that future researchers can use BIA in any field setting and increase the accuracy of BIA-based estimates of per cent dry mass. PMID:25425157

Hafs, A W; Hartman, K J

2015-01-01

58

Correcting the Temperature Influence on Soil Capacitance Sensors Using Diurnal Temperature and Water Content Cycles  

PubMed Central

The influence of temperature on the dielectric permittivity of soil is the result of counteracting effect that depends on the soil's composition and mineralogy. In this paper, laboratory experiments showed that for a given water content, the soil dielectric permittivity was linearly related to the temperature, with a slope (?) that varied between samples taken in the same soil. These variations are difficult to predict and therefore, a simple and straightforward algorithm was designed to estimate ? based on the diurnal patterns of both the measured dielectric permittivity and the soil temperature. The underlying idea is to assume that soil water content variations can be known with a reasonable accuracy over an appropriate time window within a day. This allows determining the contribution of the soil water content to the dielectric permittivity variations and then, the difference with the observed measurements is attributed to the soil temperature. Implementation of the correction methods in a large number of experiments significantly improved the physical meaning of the temporal evolution of the soil water content as the daily cycles for probes located near the surface or the long-term variations for more deeply installed probes. PMID:23012569

Chanzy, André; Gaudu, Jean-Claude; Marloie, Olivier

2012-01-01

59

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

Microsoft Academic Search

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

Collie Miller; Larry Filipow; Stuart Jackson; Terence Riauka

1996-01-01

60

Testing and Evaluation of a Power Factor Correction for Power-Savings Potential  

E-print Network

Power factor correction (PFC) is an important technology that can be used to enhance power quality. It was noted that the power factor was low for packaged air-conditioning (PAC) units utilized in residential buildings in Kuwait. To study...

Alotaibi, A.

2011-01-01

61

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

62

Note: Vignetting calibration and temperature correction for casting billets.  

PubMed

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. PMID:24089881

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

2013-09-01

63

Experimental validation of beam quality correction factors for proton beams.  

PubMed

This paper presents a method to experimentally validate the beam quality correction factors (kQ) tabulated in IAEA TRS-398 for proton beams and to determine the kQ of non-tabulated ionization chambers (based on the already tabulated values). The method is based exclusively on ionometry and it consists in comparing the reading of two ionization chambers under the same reference conditions in a proton beam quality Q and a reference beam quality (60)Co. This allows one to experimentally determine the ratio between the kQ of the two ionization chambers. In this work, 7 different ionization chamber models were irradiated under the IAEA TRS-398 reference conditions for (60)Co beams and proton beams. For the latter, the reference conditions for both modulated beams (spread-out Bragg peak field) and monoenergetic beams (pseudo-monoenergetic field) were studied. For monoenergetic beams, it was found that the experimental kQ values obtained for plane-parallel chambers are consistent with the values tabulated in IAEA TRS-398; whereas the kQ values obtained for cylindrical chambers are not consistent-being higher than the tabulated values. These results support the suggestion (of previous publications) that the IAEA TRS-398 reference conditions for monoenergetic proton beams should be revised so that the effective point of measurement of cylindrical ionization chambers is taken into account when positioning the reference point of the chamber at the reference depth. For modulated proton beams, the tabulated kQ values of all the ionization chambers studied in this work were found to be consistent with each other-except for the IBA FC65-G, whose experimental kQ value was found to be 0.6% lower than the tabulated one. The kQ of the PTW Advanced Markus chamber, which is not tabulated in IAEA TRS-398, was found to be 0.997 ± 0.042 (k = 2), based on the tabulated value of the PTW Markus chamber. PMID:25813370

Gomà, Carles; Hofstetter-Boillat, Bénédicte; Safai, Sairos; Vörös, Sándor

2015-04-21

64

Corrections for the temperature conditions of tunnel kilns  

Microsoft Academic Search

tmi, where t mopt i is the optimum temperature of the material being fired in the preheating and firing zone for ensuring the statistical invariability of product quality, ~ (t m = idem) i is the temperature of the material which remains invariable in all kiln positions regardless of the truck speed and which ensures that the variation of the

I. G. Kharchenko; V. I. Ivanov; G. A. Molotkov; V. R. Starun; V. Kh. Zima

1974-01-01

65

High magnetic field corrections to resistance thermometers at low temperatures  

NASA Astrophysics Data System (ADS)

We present a reliable method to account for the magnetoresistance of resistance sensors which are used as thermometers in many low temperature (T?20 K) experiments carried out in high magnetic fields (to 31 T). To apply the method, a set of isothermal magnetoresistance data, and a zero magnetic field temperature calibration are first necessary. A simple algorithm, which uses this data set, can then be applied to compute the temperature from the measured resistance at any field. The method is particularly useful for temperature dependent measurements at fixed field, or where, in cases where the temperature may change unpredictably during a change in magnetic field. We apply this method to the treatment of data in two separate experiments with the two different thermometers, RuO2 (below 1 K) and Cernox (above 1 K) sensors, respectively.

Zhang, B.; Brooks, J. S.; Perenboom, J. A. A. J.; Han, S.-Y.; Qualls, J. S.

1999-04-01

66

Gamma ray self attenuation correction factor study. Final report  

SciTech Connect

The overall focus of this work was an attempt to better understand the nature of self attenuating particles of SNM for the purpose of developing procedures for correcting for particle self attenuation relative to improving the quantitative non-destructive assay of these materials. This report is a summary of the various schemes, calculations, data and data analysis performed relative to this subject.

NONE

1993-04-14

67

Weld pool penetration measurement using ultrasound with thermal gradient correction factors  

NASA Astrophysics Data System (ADS)

Weld penetration is critical to final weld performance. There are many techniques for determining surface parameters of weld pools but the transient nature of the pools, high temperatures and intense electromagnetic energy make direct measurement of the penetration of weld pools difficult. In order to determine weld pool penetration ultrasonically from below the weld pool it is necessary to compensate for the variation in the time of flight of the ultrasound wave due to temperature gradients. This requires both a precise understanding of the location and magnitude of the temperature gradients and the time of flight of ultrasound at the range of temperatures seen in the gradients. Given this information it is possible to develop a correction factor to an ultrasonic time of flight reading that accurately represents the actual penetration of a weld pool. This research examines the electroslag surfacing (ESS) processing of AISI 1005 low carbon steel clad onto a ductile iron substrate. The high temperature cladding on low temperature substrate provides a deep weld penetration. Ultrasonic time of flight measurements were made from a piezoelectric transducer on the backside of the substrate to the solid/liquid interface of the weld pool during welding. The speed of ultrasound over a range of temperatures was determined from furnace heated ductile iron substrates. The sample was stepped and contact piezoelectric methods used to determine time of flight. A finite element model was developed and analyzed to predict thermal gradients in the substrate around the weld pool. The model was correlated to thermocouple data of substrate heating during welding. The predicted thermal gradients and speed/temperature curves are combined with the time of flight measurement to determine the location of the solid/liquid weld interface. An automated seam tracking system for ESS was also developed. This system utilizes a line laser at right angles to the view of a CCD camera which illuminates the relief of the existing bead for the camera. Optimas software was used to locate the edge of the bead and determine the correct location for the weld head to overlap the existing bead.

Anderton, John Martin

68

Correction.  

PubMed

The printed version of last month's article Effects of snake envenomation: a guide for emergency nurses (Emergency Nurse. 22, 9, 24-29) does not describe correctly the pain relief patients with snakebite should receive. Such patients should be given paracetamol or opiate-based medication according to local guidelines. We apologise for the error. PMID:25746866

2015-03-01

69

LIGHT-DUTY DIESEL EMISSION CORRECTION FACTORS FOR AMBIENT CONDITIONS  

EPA Science Inventory

Since emission measurements from passenger cars are performed at one standard set of ambient conditions and since emission rates of HC, CO, and NOx are sensitive to temperature and humidity, it is necessary to determine the influence of ambient conditions on emissions from major ...

70

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

71

Self-attenuation correction factors for bioindicators measured by ? spectrometry for energies <100 keV  

NASA Astrophysics Data System (ADS)

The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using ? spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

Manduci, L.; Tenailleau, L.; Trolet, J. L.; De Vismes, A.; Lopez, G.; Piccione, M.

2010-01-01

72

New single-stage power-factor-corrected regulators operating in discontinuous capacitor voltage mode  

Microsoft Academic Search

The duality principle is applied to derive new single-stage power-factor-corrected regulators. This paper begins with an application of duality transformation to conventional discontinuous-mode buck, buck-boost and boost converters. The resulting dual converters operate in the discontinuous capacitor voltage mode. These new converters provide the same power factor correction property, but in the dual manner. It is proved that in the

C. K. Tse; M. H. L. Chow

1997-01-01

73

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

74

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

75

Joint bias correction of temperature and precipitation in climate model simulations  

NASA Astrophysics Data System (ADS)

Bias correction of meteorological variables from climate model simulations is a routine strategy for circumventing known limitations of state-of-the-art general circulation models. Although the assessment of climate change impacts often depends on the joint variability of multiple variables, commonly used bias correction methodologies treat each variable independently and do not consider the relationship among variables. Independent bias correction can therefore produce non-physical corrections and may fail to capture important multivariate relationships. Here, we introduce a joint bias correction methodology (JBC) and apply it to precipitation (P) and temperature (T) fields from the fifth phase of the Climate Model Intercomparison Project (CMIP5) model ensemble. This approach is based on a general bivariate distribution of P-T and can be seen as a multivariate extension of the commonly used univariate quantile mapping method. It proceeds by correcting either P or T first and then correcting the other variable conditional upon the first one, both following the concept of the univariate quantile mapping. JBC is shown to not only reduce biases in the mean and variance of P and T similarly to univariate quantile mapping, but also to correct model-simulated biases in P-T correlation fields. JBC, using methods such as the one presented here, thus represents an important step in impacts-based research as it explicitly accounts for inter-variable relationships as part of the bias correction procedure, thereby improving not only the individual distributions of P and T, but critically, their joint distribution.

Li, Chao; Sinha, Eva; Horton, Daniel E.; Diffenbaugh, Noah S.; Michalak, Anna M.

2014-12-01

76

Temperature correction of arterial blood-gas parameters: A comparative review of methodology.  

PubMed

The need for accurate clinical diagnosis and appropriate intervention requires that a modern blood-gas laboratory have the means to correct for significant discrepancies between patient temperature and the temperature at which in vitro blood samples are analyzed. Recent advances in mini- and microcomputer technology permit application of any or all of the correction formulas above at modest cost and minimal inconvenience (See the Appendix). An expanded program for a TI-59 desk-top calculator and P-100C printer which gives labeled hard-copy readout of temperature-corrected pH, PCO2, PO2, and hemoglobin saturation values, as well as bicarbonate concentration and in vivo base excess is in daily clinical use in our operating room and is available from the authors upon request. PMID:6791530

Andritsch, R F; Muravchick, S; Gold, M I

1981-09-01

77

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

78

Sensitivity and specificity of MMPI-2 neurologic correction factors: receiver operating characteristic analysis.  

PubMed

A number of Minnesota Multiphasic Personality Inventory-2 (MMPI-2) items have been hypothesized to reflect neurologic symptomatology, rather than psychopathology, among closed-head-injury (CHI) patients. Some investigators have proposed a correction factor interpretive approach, which involves the deletion of such items from the MMPI-2 profile, as a method of reducing the probability of artificial clinical scale elevations due to the symptoms of CHI. The present study employed receiver operating characteristic (ROC) analysis to evaluate the sensitivity and specificity of three correction factors. All three factors demonstrated strong sensitivity when discriminating CHI patients from normal individuals but demonstrated poor specificity when discriminating CHI patients from psychiatric patients. These findings suggest that caution should be applied in using MMPI-2 neurologic correction factors, particularly with patients who might have comorbid psychiatric conditions. PMID:14503653

Glassmire, David M; Kinney, Dominique I; Greene, Roger L; Stolberg, Ronald A; Berry, David T R; Cripe, Lloyd

2003-09-01

79

Automatic air and surface temperature measure by IR thermography with perspective correction  

NASA Astrophysics Data System (ADS)

Large building quantitative inspection needs both automatic correction of perspective distortion and precise air and surface temperature measurement. Unfortunately these operations are heavily time consuming if performed manually by a human operator. We present a dedicated algorithm devoted to this task. The procedure first of all detects suitable reference structures put in the field of view, by means of a visual image processing and identifies the 3D position of the wall. The second step matches the thermogram with the visual image of the object. The third step performs an inverse perspective projection applying a thermal camera model, the output is a corrected radiance field. The fourth step measures the air temperature on the reference and the surface temperature map. The surface temperature can be obtained by absolute, relative or differential methods mainly depending on object emissivity value and its spatial distribution.

Bison, Paolo G.; Bressan, Chiara; Grinzato, Ermanno G.; Marinetti, Sergio

1993-05-01

80

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

81

Atmospheric correction of AMSR-E brightness temperatures for dry snow cover mapping  

Microsoft Academic Search

Differences between the brightness temperatures (spectral gradient) collected by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) at 18.7 and 36.5 GHz are used to map the snow-covered area (SCA) over a region including the western U.S. The brightness temperatures are corrected to take into account for atmospheric effects by means of a simplified radiative transfer equation whose parameters are

Marco Tedesco; James R. Wang

2006-01-01

82

Mach-uniformity through the coupled pressure and temperature correction algorithm  

SciTech Connect

We present a new type of algorithm: the coupled pressure and temperature correction algorithm. It is situated in between the fully coupled and the fully segregated approach, and is constructed such that Mach-uniform accuracy and efficiency are obtained. The essential idea is the separation of the convective and the acoustic/thermodynamic phenomena: a convective predictor is followed by an acoustic/thermodynamic corrector. For a general case, the corrector consists of a coupled solution of the energy and the continuity equations for both pressure and temperature corrections. For the special case of an adiabatic perfect gas flow, the algorithm reduces to a fully segregated method, with a pressure-correction equation based on the energy equation. Various test cases are considered, which confirm that Mach-uniformity is obtained.

Nerinckx, Krista [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Krista.Nerinckx@UGent.be; Vierendeels, Jan [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Jan.Vierendeels@UGent.be; Dick, Erik [Department of Flow, Heat and Combustion Mechanics, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium)]. E-mail: Erik.Dick@UGent.be

2005-07-01

83

Monte Carlo calculated correction factors for primary standards of air kerma.  

PubMed

Many laboratories with cavity chambers as primary standards for air kerma are considering using additional Monte Carlo calculated correction factors, in particular the correction for attenuation and scatter in the walls, Kwall, and possibly the correction for point of measurement, Kan. Standards labs also use Monte Carlo calculated Spencer-Attix stopping-power ratios for graphite to air. The purpose of this article is to investigate the sensitivity of these calculations to their details and to assign uncertainties to the calculated values. We also investigate the correction needed for the Canadian primary standard to account for a polystyrene insulator, Kcomp and find that it is quite large (1.0046 +/- 0.0017). The article shows that the values of correction factors are very robust and insensitive to most details of the calculations except the values of the underlying electron stopping powers which have a significant effect on the stopping-power ratio and on Kcomp. The 1% uncertainties on the photon cross-sections have a negligible effect on these correction factors except for Kcomp. As a result of these investigations, with no change in the stopping power data used, the Canadian primary standard of air kerma in a 60Co beam needs to be increased by 0.54%. PMID:12722804

Rogers, D W O; Kawrakow, Iwan

2003-04-01

84

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

85

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

86

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...

87

An improved method for correction of air temperature measured using different radiation shields  

NASA Astrophysics Data System (ADS)

The variation of air temperature measurement errors using two different radiation shields (DTR502B Vaisala, Finland, and HYTFZ01, Huayun Tongda Satcom, China) was studied. Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012. Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers (FRP) Stevenson screen. In most cases, the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield. The measured errors changed sharply at sunrise and sunset, and reached maxima at noon. Their diurnal variation characteristics were, naturally, related to changes in solar radiation. The relationships between the record errors, global radiation, and wind speed were nonlinear. An improved correction method was proposed based on the approach described by Nakamura and Mahrt (2005) (NM05), in which the impact of the solar zenith angle (SZA) on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively. Measurement errors were reduced significantly after correction by either method for both shields. The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3% and 40.4% higher than those using the NM05 method, respectively.

Cheng, Xinghong; Su, Debin; Li, Deping; Chen, Lu; Xu, Wenjing; Yang, Meilin; Li, Yongcheng; Yue, Zhizhong; Wang, Zijing

2014-11-01

88

A modification of the Avrett-Krook temperature-correction procedure.  

NASA Technical Reports Server (NTRS)

In the course of developing a computer program for blanketed model stellar atmospheres, it was found that near the surface the Avrett-Krook temperature correction procedure (1963) has poor convergence properties. The problem is most apparent when frequencies shortward of the Lyman discontinuity are included. Slightly different assumptions have been made to improve the convergence.

Karp, A. H.

1972-01-01

89

Calculation of the Pitot tube correction factor for Newtonian and non-Newtonian fluids.  

PubMed

This paper presents the numerical investigation performed to calculate the correction factor for Pitot tubes. The purely viscous non-Newtonian fluids with the power-law model constitutive equation were considered. It was shown that the power-law index, the Reynolds number, and the distance between the impact and static tubes have a major influence on the Pitot tube correction factor. The problem was solved for a wide range of these parameters. It was shown that employing Bernoulli's equation could lead to large errors, which depend on the magnitude of the kinetic energy and energy friction loss terms. A neural network model was used to correlate the correction factor of a Pitot tube as a function of these three parameters. This correlation is valid for most Newtonian, pseudoplastic, and dilatant fluids at low Reynolds number. PMID:14582876

Etemad, S Gh; Thibault, J; Hashemabadi, S H

2003-10-01

90

Correction of temperature influence on the wind retrieval from a mobile Rayleigh Doppler lidar  

NASA Astrophysics Data System (ADS)

A mobile Rayleigh Doppler lidar based on double-edge technique is implemented for simultaneously observing wind and temperature at heights of 15 km–60 km away from ground. Before the inversion of the Doppler shift due to wind, the Rayleigh response function should be calculated, which is a convolution of the laser spectrum, Rayleigh backscattering function, and the transmission function of the Fabry–Perot interferometer used as the frequency discriminator in the lidar. An analysis of the influence of the temperature on the accuracy of the line-of-sight winds shows that real-time temperature profiles are needed because the bandwidth of the Rayleigh backscattering function is temperature-dependent. An integration method is employed in the inversion of the temperature, where the convergence of this method and the high signal-to-noise ratio below 60 km ensure the accuracy and precision of the temperature profiles inverted. Then, real-time and on-site temperature profiles are applied to correct the wind instead of using temperature profiles from a numerical prediction system or atmosphere model. The corrected wind profiles show satisfactory agreement with the wind profiles acquired from radiosondes, proving the reliability of the method. Project supported by the National Natural Science Foundation of China (Grant Nos. 41174130, 41174131, 41274151, and 41304123).

Zhao, Ruo-Can; Xia, Hai-Yun; Dou, Xian-Kang; Sun, Dong-Song; Han, Yu-Li; Shangguan, Ming-Jia; Guo, Jie; Shu, Zhi-Feng

2015-02-01

91

New look at displacement factor and point of measurement corrections in ionization chamber dosimetry  

SciTech Connect

A new technique is presented for determination of the effective point of measurement when cavity ionization chambers are used to measure the absorbed dose due to ionizing radiation in a dense medium. An algorithm is derived relating the effective point of measurement to the displacement correction factor. This algorithm relates variations of the displacement factor to the radiation field gradient. The technique is applied to derive the magnitudes of the corrections for several chambers in a p(66)Be(49) neutron therapy beam. 30 references, 4 figures, 1 table.

Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

1983-01-01

92

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; Lépy, M-C; Martinkovi?, J; Ramebäck, H; Sima, O; Tzika, F; Vidmar, G

2014-05-01

93

BCS instability and finite temperature corrections to tachyon mass in intersecting D1-branes  

NASA Astrophysics Data System (ADS)

A holographic description of BCS superconductivity is given in [1]. This model was constructed by insertion of a pair of D8-branes on a D4-background. The spectrum of intersecting D8-branes has tachyonic modes indicating an instability which is identified with the BCS instability in superconductors. Our aim is to study the stability of the intersecting branes under finite temperature effects. Many of the technical aspects of this problem are captured by a simpler problem of two intersecting D1-branes on flat background. In the simplified set-up we compute the one-loop finite temperature corrections to the tree-level tachyon mass-squared-squared using the frame-work of SU(2) Yang-Mills theory in (1 + 1)-dimensions. We show that the one-loop two-point functions are ultraviolet finite due to cancellation of ultraviolet divergence between the amplitudes containing bosons and fermions in the loop. The amplitudes are found to be infrared divergent due to the presence of massless fields in the loops. We compute the finite temperature mass-squared correction to all the massless fields and use these temperature dependent masses-squared to compute the tachyonic mass-squared correction. We show numerically the existence of a transition temperature at which the effective mass-squared of the tree-level tachyons becomes zero, thereby stabilizing the brane configuration.

Chowdhury, Sudipto Paul; Sarkar, Swarnendu; Sathiapalan, B.

2014-09-01

94

QCD factorization for hadronic B decays: Proofs and higher-order corrections  

NASA Astrophysics Data System (ADS)

Several issues related to the QCD factorization approach to exclusive hadronic B decays are discussed. This includes a proof of factorization in B ? K*gamma using the soft-collinear effective theory, and an examination of higher-order corrections to QCD factorization for two-body decays into heavy-light states, such as B ? Dpi, and light-light final states, such as B ? Kpi,pipi. The proof of factorization in B ? K*gamma is arguably the most complicated QCD factorization formula proven so far. It is shown that reparameterization invariance in the intermediate effective theory restricts the appearance of transverse momentum components and 3-particle Fock states to operators that can be absorbed into the QCD from factor. This proof also includes an extension of SCET to deal with two collinear directions. The examination of higher-order corrections to QCD factorization has implications for using this technique to extract CP violating weal; phases from data taken at the B factories. The renormalon calculus is used to calculate the b0a2s contributions to the hard scattering kernels, and also to analyze the strength of power corrections due to soft gluon exchange. It is shown that while power corrections are generally small, the higher-order perturbative contributions to the hard scattering kernels have much larger imaginary parts than those at next-to-leading order (NLO). This significantly enhances some CP asymmetries compared to the NLO results, which is an effect that would survive a two-loop calculation unless there were large multi-loop corrections not related to the b0a2s terms of the perturbative expansion.

Pecjak, Benjamin Dale

95

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

96

Correction  

NASA Astrophysics Data System (ADS)

High-temperature arc-parallel normal faulting and transtension at the roots of an obliquely convergent orogen, Klepeis, K. A., and Crawford, M. L. Geology, v. 27, p. 7 10 (January 1999) References to work on dextral transpression and extension in the Coast Mountains developed independently by colleagues at Princeton University as part of the ACCRETE project were omitted from this University as part of the ACCRETE project were omitted from this that the observations published in these references appear completely compatible with their model of sinistral transtension. They also acknowledge the Princeton group for collaboration during the course of these studies. Andronicos C. L., Hollister, L. S., and Davidson, C., 1997, Dextral transpressive shearing at the eastern margin of the Quottoon pluton: Implications for the evolution of the Coast shear zone: Geological Society of America Abstracts with Programs, v. 29, no. 6, p. 83. Chardon, D., and Andronicos, C. L., 1997, The Central Gneiss Complex: An asymmetrical extensional gneiss dome bounded by the Coast shear zone: Geological Society of America Abstracts with Programs, v. 29, no. 6, p. 84. Hollister, L. S., and Andronicos, C. L., 1997, A candidate for the Baja British Columbia fault system in the Coast Plutonic Complex: GSA Today, no. 11, p. 1 7.

1999-07-01

97

Temperature corrected transepithelial electrical resistance (TEER) measurement to quantify rapid changes in paracellular permeability.  

PubMed

Determining the transepithelial electrical resistance (TEER) is a widely used method to functionally analyze tight junction dynamics in cell culture models of physiological barriers. Changes in temperature are known to have strong effects on TEER and can pose problems during the process of TEER measurements in cell culture vessels, complicating comparisons of TEER data across different experiments and studies. Here, we set out to devise a strategy to obtain temperature-independent TEER values based on the physical correlation between parameters such as TEER, temperature, medium viscosity and pore size of the cell culture inserts. By measuring the impact of temperature and different electrode types on TEER measurements on Caco-2 and HPDE (normal human pancreatic ductal epithelium) monolayers, we were able to derive a mathematical method that is suitable for the correction of TEER values for temperature changes. Applying this method to raw TEER values yields temperature-corrected TEER (tcTEER) values. Validity of tcTEER was demonstrated by showing a direct correlation with permeability of monolayers as determined by flux of RITC dextran. Taken together, the mathematical solution presented here allows for a simple and accurate determination of paracellular permeability independent of temperature variation during the process of TEER recording. PMID:20187574

Blume, L-F; Denker, M; Gieseler, F; Kunze, T

2010-01-01

98

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; Fernández-Varea, José M.; Izewska, Joanna

2010-03-01

99

Water temperature-influential factors, field measurement, and data presentation  

USGS Publications Warehouse

This manual contains suggested procedures for collecting and reporting of water-temperature data on streams, lakes and reservoirs, estuaries, and ground water. Among the topics discussed are the selection of equipment and measuring sites, objectives and accuracy of measurements, and data processing and presentation. Background information on the influence of temperature on water quality and the factors influencing water temperature are also presented.

Stevens, Herbert H.; Ficke, John F.; Smoot, George F.

1975-01-01

100

An active power factor correction technique for three-phase diode rectifiers  

Microsoft Academic Search

A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It

A. R. Prasad; Phoivos D. Ziogas; Stefanos Manias

1991-01-01

101

An active power factor correction technique for three-phase diode rectifiers  

Microsoft Academic Search

A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single-switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It is

A. R. Prasad; P. D. Ziogas; S. Manias

1989-01-01

102

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

103

Bias correction of temperature produced by the Community Climate System Model using Artificial Neural Networks  

NASA Astrophysics Data System (ADS)

General Circulation Models (GCMs) are used to predict circulation and energy transfers between the atmosphere and the land. It is known that these models produce biased results that will have impact on their uses. This work proposes a new method for bias correction: the equidistant cumulative distribution function-artificial neural network (EDCDFANN) procedure. The method uses artificial neural networks (ANNs) as a surrogate model to estimate bias-corrected temperature, given an identification of the system derived from GCM models output variables. A two-layer feed forward neural network is trained with observations during a historical period and then the adjusted network can be used to predict bias-corrected temperature for future periods. To capture the extreme values this method is combined with the equidistant CDF matching method (EDCDF, Li et al. 2010). The proposed method is tested with the Community Climate System Model (CCSM3) outputs using air and skin temperature, specific humidity, shortwave and longwave radiation as inputs to the ANN. This method decreases the mean square error and increases the spatial correlation between the modeled temperature and the observed one. The results indicate the EDCDFANN has potential to remove the biases of the model outputs.

Moghim, S.; Hsu, K.; Bras, R. L.

2013-12-01

104

Evaluating atmospheric correction models for retrieving surface temperatures from the AVHRR over a tallgrass prairie  

NASA Technical Reports Server (NTRS)

The effects of atmospheric attenuation on surface radiative temperatures obtained by the AVHRR over a tallgrass prairie area in the Flint Hills of Kansas are examined. Six atmospheric correction models developed primarily for sea-surface temperature studies are used to test their utility for retrieval of radiative temperatures over the land surface. An uncertainty of + or - 3.0 C was found for the AVHRR data, and used to evaluate the performance of a given model. When the difference between in situ and AVHRR surface temperatures was smaller than the uncertainty, the model was judged to be adequate. Among the six models evaluated, only the NOAA split-window model consistently adjusted the AVHRR surface temperatures within + or - 3.0 C of the in situ measurements.

Cooper, D. I.; Asrar, G.

1989-01-01

105

The accuracy of climate models' simulated season lengths and the effectiveness of grid scale correction factors  

SciTech Connect

Global climate change is expected to impact biological populations through a variety of mechanisms including increases in the length of their growing season. Climate models are useful tools for predicting how season length might change in the future. However, the accuracy of these models tends to be rather low at regional geographic scales. Here, I determined the ability of several atmosphere and ocean general circulating models (AOGCMs) to accurately simulate historical season lengths for a temperate ectotherm across the continental United States. I also evaluated the effectiveness of regional-scale correction factors to improve the accuracy of these models. I found that both the accuracy of simulated season lengths and the effectiveness of the correction factors to improve the model's accuracy varied geographically and across models. These results suggest that regional specific correction factors do not always adequately remove potential discrepancies between simulated and historically observed environmental parameters. As such, an explicit evaluation of the correction factors' effectiveness should be included in future studies of global climate change's impact on biological populations.

Winterhalter, Wade

2011-09-01

106

The accuracy of climate models' simulated season lengths and the effectiveness of grid scale correction factors.  

PubMed

Global climate change is expected to impact biological populations through a variety of mechanisms including increases in the length of their growing season. Climate models are useful tools for predicting how season length might change in the future. However, the accuracy of these models tends to be rather low at regional geographic scales. Here, I determined the ability of several atmosphere and ocean general circulating models (AOGCMs) to accurately simulate historical season lengths for a temperate ectotherm across the continental United States. I also evaluated the effectiveness of regional-scale correction factors to improve the accuracy of these models. I found that both the accuracy of simulated season lengths and the effectiveness of the correction factors to improve the model's accuracy varied geographically and across models. These results suggest that regional specific correction factors do not always adequately remove potential discrepancies between simulated and historically observed environmental parameters. As such, an explicit evaluation of the correction factors' effectiveness should be included in future studies of global climate change's impact on biological populations. PMID:21939063

Winterhalter, Wade E

2011-09-01

107

The perturbation correction factor of ionisation chambers in beta -radiation fields  

Microsoft Academic Search

In determining the absorbed dose in a solid medium by means of gas-filled ionisation chambers, the perturbation of the radiation field by the chamber needs to be taken into account. So far, an appropriate correction factor has neither been calculated nor measured for beta -radiation. This work describes its experimental determination for an extrapolation chamber and beta -radiation fields of

J. Bohm

1980-01-01

108

GENETIC IMPROVEMENT Establishment of correction factors of litter size for age  

E-print Network

V. - GENETIC IMPROVEMENT Establishment of correction factors of litter size for age of dam numbers of piglets born, born alive and weaned in 3_5 441 Large It'hile, litters, !z9 Blanc de l'Ouest litters, 9222 French Landrace titters, i;9! Pictrain litters and 4129 Belgian Landrace litters vccre used

Paris-Sud XI, Université de

109

Comparative Study of Power Factor Correction Converters For Single Phase Half-Bridge Inverters  

E-print Network

to the dc bus. Many battery cells connected in series are required to support a high dc bus voltage, which is about twice the peak line voltage. This re- quirement of a high voltage storage battery leads an isolation transformer, and sinu- soidal input currents if a power factor correction (PFC) con- verter

Tolbert, Leon M.

110

Microcontroller Power Mode Stabilized Power Factor Correction Stage for High Intensity Discharge Lamp Electronic Ballast  

Microsoft Academic Search

This paper presents new design considerations and a control strategy for a two-stage ballast system; power factor correction (PFC) and resonant inverter (RI), for high intensity discharge lamps. The ballast includes a microcontroller whose proposed algorithm implements a power loop and a voltage loop, both to control the PFC, and generates the transistor drive signals of the RI. The power

Francisco J. Azcondo; F. Javier Diaz; Christian Branas; Rosario Casanueva

2007-01-01

111

Correction factor to dye-measured flow velocity under varying water and sediment discharges  

Technology Transfer Automated Retrieval System (TEKTRAN)

Dye-tracing technique was a widely used method to measure velocity of overland flow in soil erosion studies under both laboratory and field conditions. Few studies were performed to quantify the effects of sediment load on correction factor on steep slopes. The objective was to investigate the poten...

112

Correction factor for continuous monitoring of wood smoke fine particulate matter  

PubMed Central

The US Environmental Protection Agency (EPA) has designated a handful of instruments as Federal Reference or Federal Equivalency Methods (FRM and FEM, respectively) for the monitoring of fine particulate matter (PM2.5). More commonly used for indoor exposure assessment studies are optical scanning devices such as the DustTrak (TSI) due to the their portability and affordability. It is recommended by the manufacturer of these instruments that a “correction factor” be applied when assessing source-specific conditions. In this study, DustTraks were collocated with multiple samplers in various environments in an effort to establish an indoor, wood smoke-source specific correction factor. The DustTrak was found to report PM2.5 levels on average 1.6 times higher than a filter based method in two indoor sampling programs. The DustTrak also reported indoor PM2.5 concentrations 1.7 times higher than a FRM sampler during a regional forest fire event. These real-world scenarios give a correction factor within a reasonable range of the results of a controlled laboratory experiment in which DustTraks reported PM2.5 approximately 2 times higher than a FEM. Our indoor wood smoke-specific correction factor of 1.65 will allow for DustTraks to be confidently used in quantifying PM2.5 exposures within indoor environments predominantly impacted by wood smoke. PMID:25364330

McNamara, Marcy L.; Noonan, Curtis W.; Ward, Tony J.

2012-01-01

113

Factors Related to Recidivism Among Delinquent Youths in a State Correctional Facility  

Microsoft Academic Search

Identifying and remediating variables accounting for recidivism has been a persistent and often controversial challenge. We investigated factors that may be related to recidivism among delinquent youths committed to a state correctional facility. Data were collected by examining the records of 147 recidivists and 147 non-recidivists. Our findings are consistent with previous research showing age of first offense and first

Antonis Katsiyannis; Teara Archwamety

1997-01-01

114

Comparative analysis of three interleaved boost power factor corrected topologies in DCM  

Microsoft Academic Search

The aim of this paper is to analyze in a comparative manner three interleaved boost power factor corrected (PFC) topologies that alleviate some of the conventional boost PFC shortcomings like high input current ripple and current stress. A parallel interleaved topology and two novel serial topologies especially suitable for electronic ballast applications are considered. The boost inductor current and size

R. Teodorescu; S. B. Kjaer; S. Munk-Nielsen; F. Blaabjerg; J. K. Pedersen

2001-01-01

115

76 FR 19913 - Compliance Testing Procedures: Correction Factor for Room Air Conditioners  

Federal Register 2010, 2011, 2012, 2013, 2014

...a data correction factor in compliance testing procedures for room air conditioners...regulations governing DOE's compliance testing procedures at that time. The petition...using IMST-ART version 3.30 modeling software of five simulations, in each case...

2011-04-11

116

Determining correction factors for seasonal and regional variability in the tracer ratio method  

E-print Network

: The seasonal variability in the CFC-12:CO and CFC-11:CO enhancement ratios, observed during a three year period correction factors for HFC-134a (the main CFC-12 replacement) and HFC-152a emissions estimates (CFC-11 also. (2003) was about 40% (for X = CFC-12) and 30% (for X = CFC-11) higher than the average annual

Meskhidze, Nicholas

117

Linear elevator velocity control system based on correction factor fuzzy PID  

Microsoft Academic Search

The elevator cab will vibrate because of the edge effect in the linear elevators that is driven by the permanent magnet linear synchronous motor (PMLSM). This article adopts correction factor fuzzy - PID control method in order to solve the vibration of elevator cab. The fuzzy control is not completely dependent on the mathematics model, but the fuzzy rules are

Haiyan Yu; Qing Hu; Jing Zhang

2008-01-01

118

Gradient corrections to the kinetic energy density functional of a two-dimensional Fermi gas at finite temperature  

Microsoft Academic Search

We examine the leading-order semiclassical gradient corrections to the noninteracting kinetic-energy density functional of a two-dimensional Fermi gas by applying the extended Thomas-Fermi theory at finite temperature. We find a nonzero von Weizsäcker-like gradient correction, which in the high-temperature limit goes over to the functional form (ℏ2\\/24m)(?rho)2\\/rho. Our work provides a theoretical justification for the inclusion of gradient corrections in

B. P. van Zyl; K. Berkane; K. Bencheikh; A. Farrell

2011-01-01

119

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

120

REFINEMENT OF THE STREAM TEMPERATURE NETWORK MODEL WITH CORRECTIONS FOR SOLAR SHADINGS AND INFLOW TEMPERATURES  

NASA Astrophysics Data System (ADS)

A basin-wide stream network model was developed for stream temperature prediction in a river basin. The model used Horton’s geomorphologic laws for channel networks and river basins with stream ordering systems in order to connect channel segments from sources to the river mouth. Within the each segment, a theoretical solution derived from a thermal energy equation was used to predict longitudinal variation of stream temperatures. The model also took into account effects of solar radiation reduction due to both riparian vegetation and topography, thermal advection from the sources and lateral land-use. Comparison of the model prediction with observation in the Ibo River Basin of Japan showed very good agreement for the thermal structure throughout the river basin for almost all seasons, excluding the autumnal month in which the thermal budget on the stream water body was changed from positive to negative.

Miyamoto, Hitoshi; Maeba, Hiroshi; Nakayama, Kazuya; Michioku, Kohji

121

Bias correction of temperature and precipitation data for regional climate model application to the Rhine basin  

NASA Astrophysics Data System (ADS)

The Hydrology and Quantitative Water Management group of Wageningen University is involved in the EU research project NeWater. The objective of this project is to develop tools which provide medium range hydrological predictions by coupling catchment-scale water balance models and ensembles from mesoscale climate models. The catchment-scale distributed hydrological model used in this study is the Variable Infiltration Capacity (VIC) model. This hydrological model in combination with an ensemble from the climate model ECHAM5 (developed by Max Plank Institute für Meteorologie (MPI-M), Hamburg) is being used to evaluate the effects of climate change on the hydrological regime of the Rhine basin and to assess the uncertainties involved in the ensembles from the climate model used in this study. Three future scenarios (2001-2100) are used in this study, which are downscaled ECHAM5 runs which were forced by the IPCC carbon emission scenarios B1, A1B and A2. A downscaled ECHAM5 "Climate of the 20th Century" run (1951-2000) is used as the reference climate. Downscaled ERA15 data is used to calibrate the VIC model. Downscaling of both the ECHAM5 and ERA15 model was carried out with the regional climate model REMO at MPI-M to a resolution of 0.088 degrees. The assessment of uncertainties involved in the climate model ensembles is performed by comparing the model (ECHAM5-REMO and ERA15-REMO) ensemble precipitation and temperature data with observations. This resulted in the detection of a bias in both the downscaled reference climate data and downscaled ERA15 data. A bias-correction has been applied to both the downscaled ERA15 data and the reference climate data. This bias-correction corrects for the mean and coefficient of variation for precipitation and the mean and standard deviation for temperature. The results of the applied bias-correction are analyzed spatially and temporally. Despite the fact that the bias-correction only uses two parameters, the coefficient of variation, standard deviation and mean of the bias-corrected data sets showed significant improvements for both precipitation and temperature. Even statistics that were not taken into account in the bias-correction, such as the fraction of wet days, the lag-one autocorrelation and the exceedance probabilities have improved as well.

Terink, W.; Hurkmans, R. T. W. L.; Uijlenhoet, R.; Torfs, P. J. J. F.; Warmerdam, P. M. M.

2009-04-01

122

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

123

Low-Temperature Thermoelectric Power Factor Enhancement by Controlling  

E-print Network

applications in waste heat recovery. The energy conversion efficiency depends on the material's dimensionlessLow-Temperature Thermoelectric Power Factor Enhancement by Controlling Nanoparticle Size nanoparticles inside a host matrix on the thermoelectric properties. This takes into account electron multiple

124

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

125

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

126

A new high performance AC to DC rectifier with input power factor correction and harmonic reduction capacity  

E-print Network

, this thesis examines the cause and effects of low power factor and harmonic current in single phase rectifiers; provides a thorough review of previous correction techniques; and presents a new approach for ac to dc rectification with input power factor...

Martinez, Roberto

1994-01-01

127

Monte Carlo simulated correction factors for output factor measurement with the CyberKnife system-results for new detectors and correction factor dependence on measurement distance and detector orientation.  

PubMed

A previous study of the corrections needed for output factor measurements with the CyberKnife system has been extended to include new diode detectors (IBA SFD and Exradin D1V), an air filled microchamber (Exradin CC01) and a scintillation detector (Exradin W1). The dependence of the corrections on detector orientation (detector long axis parallel versus perpendicular to the beam axis) and source to detector distance (SDD) was evaluated for these new detectors and for those in our previous study. The new diodes are found to over-respond at the smallest (5 mm) field size by 2.5% (D1V) and 3.3% (SFD) at 800 mm SDD, while the CC01 under-responds by 7.4% at the same distance when oriented parallel to the beam. Corrections for all detectors tend to unity as field size increases. The W1 corrections are <0.5% at all field sizes. Microchamber correction factors increase substantially if the detector is oriented perpendicular to the beam (by up to 23% for the PTW 31014). Corrections also vary with SDD, with the largest variations seen for microchambers in the perpendicular orientation (up to 13% change at 650 mm SDD versus 800 mm) and smallest for diodes (~1% change at 650 mm versus 800 mm). The smallest and most stable corrections are found for diodes, liquid filled microchambers and scintillation detectors, therefore these should be preferred for small field output factor measurements. If air filled microchambers are used, then the parallel orientation should be preferred to the perpendicular, and care should be taken to use corrections appropriate to the measurement SDD. PMID:24594929

Francescon, P; Kilby, W; Satariano, N

2014-03-21

128

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 ±7.2°C changing by 0.5°C/min, this method produced a camera calibration with spatial-temporal rms variability of 0.21°C, yielding a total calibration uncertainty of 0.38°C limited primarily by the 0.32°C uncertainty in the blackbody source emissivity and temperature.

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

2013-06-01

129

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

130

Temperature and precipitation as limiting factors in ecosystems  

NSDL National Science Digital Library

This classroom activity is aimed at an understanding of different ecosystems by understanding the influence of temperature and precipitation. Students correlate graphs of vegetation vigor with those of temperature and precipitation data for four diverse ecosystems, ranging from near-equatorial to polar, and spanning both hemispheres to determine which climatic factor is limiting growth.

GLOBE Project

131

Introduction Temperature is regarded as an `ecological master factor' for  

E-print Network

of arterial and venous blood occur with increasing water temperature in resting rainbow trout We examined stimulation also increased the cardiac sensitivity to filling pressure, with the maximum left1216 Introduction Temperature is regarded as an `ecological master factor' for fish because of its

Farrell, Anthony P.

132

Frequency Scalable Non-Linear Waveform Generator for Mixed-Simal Power-Factor-Correction IC Controller'  

E-print Network

Frequency Scalable Non-Linear Waveform Generator for Mixed-Simal Power-Factor-Correction IC mixed-signal IC controller for power-factor-correction (PFC) of high-frequency switching AC have been developed for input current shaping [1]-[4],along with some analog IC imple- mentations 1121

133

Correction factors for the self-absorption of gamma-rays in a cylindrical sample  

Microsoft Academic Search

A distribution of distances was calculated which a gamma-ray will travel in order to escape from a cylindrical sample with a radius of 5 mm and a length of 20 mm in a solid angle of 2 sr. From this distribution, attenuation factors were calculated for linear attenuation coefficients varying from 0.001 to 9 (mm-1) and from these corrections the

L. Zikovsky

1984-01-01

134

A soft-switching mode rectifier with power factor correction and high frequency transformer link  

Microsoft Academic Search

This paper presents a soft-switching mode rectifier (SSMR) consisting of a power factor correction zero-voltage-transition-pulse-width-modulated (PFC ZVT-PWM) converter and a high-frequency transformer-coupled DC\\/DC zero voltage switching clamped voltage (ZVS-CV) converter. An easily implemented ZVT soft-switching mechanism is developed to reduce the switching losses and stresses of the power switches in the PFC ZVT-PWM converter. The operations of the proposed SSMR

Chang-Ming Liaw; Thin-Huo Chen

2000-01-01

135

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

136

Application of duality principle to synthesis of single-stage power-factor-correction voltage regulators  

Microsoft Academic Search

SUMMARY The duality principle is applied to derive new single-stage power-factor-correction (PFC) voltage reg- ulators. This paper begins with an application of duality transformation to conventional discontinuous- conduction-mode buck, buck-boost and boost converters. The resulting dual converters operate in the discontinuous capacitor voltage mode. These new converters provide the same PFC property, but in the dual manner. It is proved

C. K. Tse; Y. M. Lai; R. J. Xie; M. H. L. Chow

2003-01-01

137

Interleaved boost-flyback converter with boundary conduction mode for power factor correction  

Microsoft Academic Search

This paper presents a new interleaved pulse-width modulation (PWM) boost-flyback converter to achieve power factor correction (PFC) and regulate DC bus voltage. The adopted boost-flyback converter has a high voltage conversion ratio to overcome the limit of conventional boost or buck-boost converter with narrow turn-off period. The proposed converter has wide turn-off period compared with a conventional boost converter. Thus

Bor-Ren Lin; Chia-Hung Chao; Chih-Cheng Chien

2011-01-01

138

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

139

Nuclear recoil correction to the g factor of boron-like argon  

NASA Astrophysics Data System (ADS)

The nuclear recoil effect to the g factor of boron-like ions is investigated. The one-photon-exchange correction to the nuclear recoil effect is calculated in the nonrelativistic approximation for the nuclear recoil operator and in the Breit approximation for the interelectronic-interaction operator. The screening potential is employed to estimate the higher-order contributions. The updated g-factor values are presented for the ground 2P1/2 and first excited 2P3/2 states of B-like argon 40Ar13+, which are presently being measured by the ARTEMIS group at GSI.

Shchepetnov, A. A.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.

2015-01-01

140

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

141

Detecting and correcting the bias of unmeasured factors using perturbation analysis: a data-mining approach  

PubMed Central

Background The randomized controlled study is the gold-standard research method in biomedicine. In contrast, the validity of a (nonrandomized) observational study is often questioned because of unknown/unmeasured factors, which may have confounding and/or effect-modifying potential. Methods In this paper, the author proposes a perturbation test to detect the bias of unmeasured factors and a perturbation adjustment to correct for such bias. The proposed method circumvents the problem of measuring unknowns by collecting the perturbations of unmeasured factors instead. Specifically, a perturbation is a variable that is readily available (or can be measured easily) and is potentially associated, though perhaps only very weakly, with unmeasured factors. The author conducted extensive computer simulations to provide a proof of concept. Results Computer simulations show that, as the number of perturbation variables increases from data mining, the power of the perturbation test increased progressively, up to nearly 100%. In addition, after the perturbation adjustment, the bias decreased progressively, down to nearly 0%. Conclusions The data-mining perturbation analysis described here is recommended for use in detecting and correcting the bias of unmeasured factors in observational studies. PMID:24499374

2014-01-01

142

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

143

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

144

Temperature-corrected pressure-sensitive paint measurements using a single camera and a dual-lifetime approach  

Microsoft Academic Search

The temperature dependence of luminescent coatings which measure surface pressure is a well established problem. Temperature correction of the surface pressure measurement is often carried out by incorporating a second luminescent coating or by co-immobilizing a second luminophore to provide a surface temperature profile. This usually complicates the measurement process by requiring a second camera or sophisticated filtering to distinguish

Jan Hradil; Claire Davis; Karen Mongey; Colette McDonagh; Brian D. MacCraith

2002-01-01

145

Analysis, compensation, and correction of temperature effects on FBG strain sensors  

NASA Astrophysics Data System (ADS)

One of the most common fiber optic sensor (FOS) types used are fiber Bragg gratings (FBG), and the most frequently measured parameter is strain. Hence, FBG strain sensors are one of the most prevalent FOS devices in use today in structural sensing and monitoring in civil engineering, aerospace, marine, oil and gas, composites and smart structure applications. However, since FBGs are simultaneously sensitive to both temperature and strain, it becomes essential to utilize sensors that are either fully temperature insensitive or, alternatively, properly temperature compensated to avoid erroneous measurements. In this paper, we introduce the concept of measured "total strain", which is inherent and unique to optical strain sensors. We review and analyze the temperature and strain sensitivities of FBG strain sensors and decompose the total measured strain into thermal and non-thermal components. We explore the differences between substrate CTE and System Thermal Response Coefficients, which govern the type and quality of thermal strain decomposition analysis. Finally, we present specific guidelines to achieve proper temperature-insensitive strain measurements by combining adequate installation, sensor packaging and data correction techniques.

Haber, T. C.; Ferguson, S.; Guthrie, D.; Graver, T. W.; Soller, B. J.; Mendez, Alexis

2013-05-01

146

Atmospheric corrections of passive microwave data for estimating land surface temperature.  

PubMed

Quantitative analysis of the atmospheric effects on observations made by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) has been performed. The differences between observed brightness temperatures at the top of the atmosphere and at the bottom of the atmosphere were analyzed using a database of simulated observations, which were configured to replicate AMSR-E data. The differences between observed brightness temperatures at the top of the atmosphere and land surface-emitted brightness temperatures were also computed. Quantitative results show that the atmosphere has different effects on brightness temperatures in different AMSR-E channels. Atmospheric effects can be neglected at 6.925 and 10.65 GHz, when the standard deviation is less than 1 K. However, at other frequencies and polarizations, atmospheric effects on observations should not be neglected. An atmospheric correction algorithm was developed at 18.7 GHz vertical polarization, based on the classic split-window algorithm used in thermal remote sensing. Land surface emission can be estimated with RMSE = 0.99 K using the proposed method. Using the known land surface emissivity, Land Surface Temperature (LST) can be retrieved. The RMSE of retrieved LST is 1.17 K using the simulated data. PMID:23842351

Liu, Zeng-Lin; Wu, Hua; Tang, Bo-Hui; Qiu, Shi; Li, Zhao-Liang

2013-07-01

147

Monte Carlo calculations of correction factors for plastic phantoms in clinical photon and electron beam dosimetry  

SciTech Connect

The purpose of this study is to calculate correction factors for plastic water (PW) and plastic water diagnostic-therapy (PWDT) phantoms in clinical photon and electron beam dosimetry using the EGSnrc Monte Carlo code system. A water-to-plastic ionization conversion factor k{sub pl} for PW and PWDT was computed for several commonly used Farmer-type ionization chambers with different wall materials in the range of 4-18 MV photon beams. For electron beams, a depth-scaling factor c{sub pl} and a chamber-dependent fluence correction factor h{sub pl} for both phantoms were also calculated in combination with NACP-02 and Roos plane-parallel ionization chambers in the range of 4-18 MeV. The h{sub pl} values for the plane-parallel chambers were evaluated from the electron fluence correction factor {phi}{sub pl}{sup w} and wall correction factors P{sub wall,w} and P{sub wall,pl} for a combination of water or plastic materials. The calculated k{sub pl} and h{sub pl} values were verified by comparison with the measured values. A set of k{sub pl} values computed for the Farmer-type chambers was equal to unity within 0.5% for PW and PWDT in photon beams. The k{sub pl} values also agreed within their combined uncertainty with the measured data. For electron beams, the c{sub pl} values computed for PW and PWDT were from 0.998 to 1.000 and from 0.992 to 0.997, respectively, in the range of 4-18 MeV. The {phi}{sub pl}{sup w} values for PW and PWDT were from 0.998 to 1.001 and from 1.004 to 1.001, respectively, at a reference depth in the range of 4-18 MeV. The difference in P{sub wall} between water and plastic materials for the plane-parallel chambers was 0.8% at a maximum. Finally, h{sub pl} values evaluated for plastic materials were equal to unity within 0.6% for NACP-02 and Roos chambers. The h{sub pl} values also agreed within their combined uncertainty with the measured data. The absorbed dose to water from ionization chamber measurements in PW and PWDT plastic materials corresponds to that in water within 1%. Both phantoms can thus be used as a substitute for water for photon and electron dosimetry.

Araki, Fujio; Hanyu, Yuji; Fukuoka, Miyoko; Matsumoto, Kenji; Okumura, Masahiko; Oguchi, Hiroshi [Department of Radiological Technology, Kumamoto University School of Health Sciences, 4-24-1, Kuhonji, Kumamoto, 862-0976 (Japan); Division of Radiation Oncology, Tokyo Women's Medical University Hospital, Tokyo, 162-8666 (Japan); Department of Central Radiology, Kinki University Hospital, Osaka, 589-8511 (Japan); Department of Central Radiology, Shinshu University Hospital, Matsumoto, 390-8621 (Japan)

2009-07-15

148

SPECTRAL CORRECTION FACTORS FOR CONVENTIONAL NEUTRON DOSEMETERS USED IN HIGH-ENERGY NEUTRON ENVIRONMENTS.  

PubMed

High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6? standard sphere). PMID:25280480

Lee, K W; Sheu, R J

2014-10-01

149

Gradient corrections to the kinetic energy density functional of a two-dimensional Fermi gas at finite temperature  

E-print Network

We examine the leading order semiclassical gradient corrections to the non-interacting kinetic energy density functional of a two dimensional Fermi gas by applying the extended Thomas-Fermi theory at finite temperature. We find a non-zero von Weizs\\"acker-like gradient correction, which in the high-temperature limit, goes over to the familiar functional form $(\\hbar^2/24m) (\

Brandon P. van Zyl; K. Berkane; K Bencheikh; A. Farrell

2011-04-07

150

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

151

Correction factors for low perturbation in vivo diodes used in the determination of entrance doses in high energy photon beams  

SciTech Connect

Purpose--Low perturbation diodes, with thin buildup caps, can be used to reduce perturbations to the delivered dose. The literature states that additional correction factors are required for low perturbation diodes, however, there are few reported studies into their use. This report measured the dose perturbations and correction factors for diodes with varying buildup cap thicknesses. Methods and materials--Scanditronix EDP15, EDD5, and EDD2 diodes were investigated. Dose perturbations and correction factors for field size, source-surface distance (SSD), obliquity, and wedge were measured in megavoltage photon beams. Results--EDP15 produces a 6% dose perturbation. EDD5 produces a perturbation between 1% and 2%. EDD2 perturbation is negligible. The variation of correction factors for the full buildup EDP15 diode is small and consistent with the literature. The low perturbation diode EDD2 has large correction factors. The field size correction factor varies from 1.38 to 0.87 for 10 MV. The SSD correction factor varies from 0.92 to 1.09 for 10 MV. At the maximum angle measured, the obliquity correction factor is 0.73 for 10 MV. Intermediate results were observed for the EDD5 diode. Conclusions--It is expected that it will be very difficult to achieve accurate in vivo dosimetry using the EDD2 diode. The EDD5 diode may represent a reasonable compromise between EDD2 and the full buildup EDP15. The EDD5 dose perturbation is small and the correction factors are not as large as for EDD2, so accurate in vivo dosimetry may be possible as long as the obliquity is below 45 degrees.

Roberts, Ralph; Philp, Amanda [Department of Medical Physics and Clinical Engineering, Oxford Radcliffe Hospitals NHS Trust, Old Road, Headington, Oxford OX3 7LJ (United Kingdom); Nuclear Medicine Department, Gloucestershire Royal Hospital, Great Western Road, Gloucester, GL1 3NN (United Kingdom)

2008-01-15

152

Temperature regulation of virulence factors in the pathogen Vibrio coralliilyticus  

PubMed Central

Sea surface temperatures (SST) are rising because of global climate change. As a result, pathogenic Vibrio species that infect humans and marine organisms during warmer summer months are of growing concern. Coral reefs, in particular, are already experiencing unprecedented degradation worldwide due in part to infectious disease outbreaks and bleaching episodes that are exacerbated by increasing SST. For example, Vibrio coralliilyticus, a globally distributed bacterium associated with multiple coral diseases, infects corals at temperatures above 27?°C. The mechanisms underlying this temperature-dependent pathogenicity, however, are unknown. In this study, we identify potential virulence mechanisms using whole genome sequencing of V. coralliilyticus ATCC (American Type Culture Collection) BAA-450. Furthermore, we demonstrate direct temperature regulation of numerous virulence factors using proteomic analysis and bioassays. Virulence factors involved in motility, host degradation, secretion, antimicrobial resistance and transcriptional regulation are upregulated at the higher virulent temperature of 27?°C, concurrent with phenotypic changes in motility, antibiotic resistance, hemolysis, cytotoxicity and bioluminescence. These results provide evidence that temperature regulates multiple virulence mechanisms in V. coralliilyticus, independent of abundance. The ecological and biological significance of this temperature-dependent virulence response is reinforced by climate change models that predict tropical SST to consistently exceed 27?°C during the spring, summer and fall seasons. We propose V. coralliilyticus as a model Gram-negative bacterium to study temperature-dependent pathogenicity in Vibrio-related diseases. PMID:22158392

Kimes, Nikole E; Grim, Christopher J; Johnson, Wesley R; Hasan, Nur A; Tall, Ben D; Kothary, Mahendra H; Kiss, Hajnalka; Munk, A Christine; Tapia, Roxanne; Green, Lance; Detter, Chris; Bruce, David C; Brettin, Thomas S; Colwell, Rita R; Morris, Pamela J

2012-01-01

153

Reexamination of ionospheric chemistry: high temperature kinetics, internal energy dependences, unusual isomers, and corrections.  

PubMed

A number of aspects of ionospheric chemistry are revisited. The review discusses in detail only work performed at AFRL, but other work is mentioned. A large portion of the paper discusses measurements of the kinetics of upper ionospheric reactions at very high temperatures, i.e. the upper temperature range has been extended to at least 1400 K and in some cases to 1800 K. These temperatures are high enough to excite vibrations in O2, N2, and NO and comparing them to drift tube data allows information on the rotational temperature and vibrational level dependences to be derived. Rotational and translational energy are equivalent in controlling the kinetics in most reactions. Vibrational energy in O2 and N2 is often found to promote reactivity which is shown to cause ionospheric density depletions. NO vibrations do not significantly affect the reactivity. In a number of cases, detailed calculations accompanied the experimental studies and elucidated details of the mechanisms. Kinetics of two peroxide isomers important in the lower ionospheric have been measured for the first time, i.e. NOO+ and ONOO-. Finally, two examples are shown where errors in previous data are corrected. PMID:16738710

Viggiano, A A

2006-06-14

154

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

155

Study of the replacement correction factors for ionization chamber dosimetry by Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

In ionization chamber radiation dosimetry, the introduction of the ion chamber into medium will unavoidably distort the radiation field near the chamber because the chamber cavity material (air) is different from the medium. A replacement correction factor, Prepl was introduced in order to correct the chamber readings to give an accurate radiation dose in the medium without the presence of the chamber. Generally it is very hard to measure the values of Prepl since they are intertwined with the chamber wall effect. In addition, the P repl values always come together with the stopping-power ratio of the two media involved. This makes the problem of determining the P repl values even more complicated. Monte Carlo simulation is an ideal method to investigate the replacement correction factors. In this study, four different methods of calculating the values of Prepl by Monte Carlo simulation are discussed. Two of the methods are designated as 'direct' methods in the sense that the evaluation of the stopping-power ratio is not necessary. The systematic uncertainties of the two direct methods are estimated to be about 0.1-0.2% which comes from the ambiguous definition of the energy cutoff Delta used in the Spencer-Attix cavity theory. The two direct methods are used to calculate the values of P repl for both plane-parallel chambers and cylindrical thimble chambers in either electron beams or photon beams. The calculation results are compared to measurements. For electron beams, good agreements are obtained. For thimble chambers in photon beams, significant discrepancies are observed between calculations and measurements. The experiments are thus investigated and the procedures are simulated by the Monte Carlo method. It is found that the interpretation of the measured data as the replacement correction factors in dosimetry protocols are not correct. In applying the calculation to the BIPM graphite chamber in a 60Co beam, the calculated values of P repl differ from those used for the chamber by about 1% which leads to 1% change in the W/e value obtained by using this chamber.

Wang, Lilie

156

Correction factors for parallel-plate chambers used in plastic phantoms in electron dosimetry  

NASA Astrophysics Data System (ADS)

In electron beam dosimetry using parallel-plate chambers solid phantoms are sometimes necessary. To obtain the dose to water from the ionization obtained in the solid phantom, fluence correction factors and perturbation factors have to be applied. In this study fluence factors in a perturbation free geometry have been determined experimentally for common phantom materials. Wall perturbation factors for simulated Attix, NACP, and Roos chambers have also been determined for the same materials. Comparative Monte Carlo calculations have been performed using the EGS4 Monte Carlo code. Comparison with data in newly published protocols such as IAEA and IPEMB shows an agreement with the results obtained in this paper to within 1%, demonstrating that the data published in these protocols may be used with reasonable accuracy if recommended phantoms are used. The results also show that if unsuitable phantom materials are used, the wall perturbation factors may differ for different chambers and for different phantom materials by more than 3% and perturbation factors have to be considered in order to obtain a high accuracy in the dose determination.

Nilsson, B.; Montelius, A.; Andreo, P.; Johansson, J.

1997-11-01

157

Correction factors for parallel-plate chambers used in plastic phantoms in electron dosimetry.  

PubMed

In electron beam dosimetry using parallel-plate chambers solid phantoms are sometimes necessary. To obtain the dose to water from the ionization obtained in the solid phantom, fluence correction factors and perturbation factors have to be applied. In this study fluence factors in a perturbation free geometry have been determined experimentally for common phantom materials. Wall perturbation factors for simulated Attix, NACP, and Roos chambers have also been determined for the same materials. Comparative Monte Carlo calculations have been performed using the EGS4 Monte Carlo code. Comparison with data in newly published protocols such as IAEA and IPEMB shows an agreement with the results obtained in this paper to within 1%, demonstrating that the data published in these protocols may be used with reasonable accuracy if recommended phantoms are used. The results also show that if unsuitable phantom materials are used, the wall perturbation factors may differ for different chambers and for different phantom materials by more than 3% and perturbation factors have to be considered in order to obtain a high accuracy in the dose determination. PMID:9394400

Nilsson, B; Montelius, A; Andreo, P; Johansson, J

1997-11-01

158

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

159

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

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Temperature derating factor (T) for steel pipe...STANDARDS Pipe Design § 192.115 Temperature derating factor (T ) for steel pipe. The temperature derating factor to be used in the...

2014-10-01

160

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Temperature derating factor (T) for steel pipe...STANDARDS Pipe Design § 192.115 Temperature derating factor (T ) for steel pipe. The temperature derating factor to be used in the...

2012-10-01

161

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

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Temperature derating factor (T) for steel pipe...STANDARDS Pipe Design § 192.115 Temperature derating factor (T ) for steel pipe. The temperature derating factor to be used in the...

2011-10-01

162

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Temperature derating factor (T) for steel pipe...STANDARDS Pipe Design § 192.115 Temperature derating factor (T ) for steel pipe. The temperature derating factor to be used in the...

2010-10-01

163

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

164

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

165

A Passive Radio-Frequency Identification (RFID) Gas Sensor With Self-Correction Against Fluctuations of Ambient Temperature.  

PubMed

Uncontrolled fluctuations of ambient temperature in the field typically greatly reduce accuracy of gas sensors. In this study, we developed an approach for the self-correction against fluctuations of ambient temperature of individual gas and vapor sensors. The main innovation of our work is in the temperature correction which is accomplished without the need for a separate uncoated reference sensor or a separate temperature sensor. Our sensors are resonant inductor-capacitor-resistor (LCR) transducers coated with sensing materials and operated as multivariable passive (battery-free) radio-frequency identification (RFID) sensors. Using our developed approach, we performed quantitation of an exemplary vapor over the temperature range from 25 to 40 °C. This technical solution will be attractive in numerous applications where temperature stabilization of a gas sensor or addition of auxiliary temperature or uncoated reference sensors is prohibitive. PMID:23956496

Potyrailo, Radislav A; Surman, Cheryl

2013-08-01

166

A Passive Radio-Frequency Identification (RFID) Gas Sensor With Self-Correction Against Fluctuations of Ambient Temperature  

PubMed Central

Uncontrolled fluctuations of ambient temperature in the field typically greatly reduce accuracy of gas sensors. In this study, we developed an approach for the self-correction against fluctuations of ambient temperature of individual gas and vapor sensors. The main innovation of our work is in the temperature correction which is accomplished without the need for a separate uncoated reference sensor or a separate temperature sensor. Our sensors are resonant inductor-capacitor-resistor (LCR) transducers coated with sensing materials and operated as multivariable passive (battery-free) radio-frequency identification (RFID) sensors. Using our developed approach, we performed quantitation of an exemplary vapor over the temperature range from 25 to 40 °C. This technical solution will be attractive in numerous applications where temperature stabilization of a gas sensor or addition of auxiliary temperature or uncoated reference sensors is prohibitive. PMID:23956496

Potyrailo, Radislav A.; Surman, Cheryl

2013-01-01

167

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

SciTech Connect

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, E-mail: guillaume.galliero@univ-pau.fr [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR-5150 with CNRS and Total, Université de Pau et des Pays de l'Adour, BP 1155, 64013 Pau (France)] [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR-5150 with CNRS and Total, Université de Pau et des Pays de l'Adour, BP 1155, 64013 Pau (France)

2014-05-21

168

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

169

THE CALCULATION OF BURNABLE POISON CORRECTION FACTORS FOR PWR FRESH FUEL ACTIVE COLLAR MEASUREMENTS  

SciTech Connect

Verification of commercial low enriched uranium light water reactor fuel takes place at the fuel fabrication facility as part of the overall international nuclear safeguards solution to the civilian use of nuclear technology. The fissile mass per unit length is determined nondestructively by active neutron coincidence counting using a neutron collar. A collar comprises four slabs of high density polyethylene that surround the assembly. Three of the slabs contain {sup 3}He filled proportional counters to detect time correlated fission neutrons induced by an AmLi source placed in the fourth slab. Historically, the response of a particular collar design to a particular fuel assembly type has been established by careful cross-calibration to experimental absolute calibrations. Traceability exists to sources and materials held at Los Alamos National Laboratory for over 35 years. This simple yet powerful approach has ensured consistency of application. Since the 1980's there has been a steady improvement in fuel performance. The trend has been to higher burn up. This requires the use of both higher initial enrichment and greater concentrations of burnable poisons. The original analytical relationships to correct for varying fuel composition are consequently being challenged because the experimental basis for them made use of fuels of lower enrichment and lower poison content than is in use today and is envisioned for use in the near term. Thus a reassessment of the correction factors is needed. Experimental reassessment is expensive and time consuming given the great variation between fuel assemblies in circulation. Fortunately current modeling methods enable relative response functions to be calculated with high accuracy. Hence modeling provides a more convenient and cost effective means to derive correction factors which are fit for purpose with confidence. In this work we use the Monte Carlo code MCNPX with neutron coincidence tallies to calculate the influence of Gd{sub 2}O{sub 3} burnable poison on the measurement of fresh pressurized water reactor fuel. To empirically determine the response function over the range of historical and future use we have considered enrichments up to 5 wt% {sup 235}U/{sup tot}U and Gd weight fractions of up to 10 % Gd/UO{sub 2}. Parameterized correction factors are presented.

Croft, Stephen [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory

2012-06-19

170

Gravity Dual Corrections to the Heavy Quark Potential at Finite-Temperature  

E-print Network

We apply gauge/gravity duality to compute $1/N^2_c$ corrections to the heavy quark potentials of a quark--anti-quark pair ($Q\\bar Q$) and of a quark--quark pair ($QQ$) immersed into the strongly coupled N = 4 SYM plasma. On the gravity side these corrections come from the exchanges of supergravity modes between two string worldsheets stretching from the UV boundary of AdS space to the black hole horizon in the bulk and smeared over $S^5$. We find that the contributions to the $Q\\bar Q$ potential coming from the exchanges of all of the relevant modes (such as dilaton, massive scalar, 2-form field, and graviton) are all attractive, leading to an attractive net $Q\\bar Q$ potential. We show that at large separations $r$ and/or high-temperature $T$ the potential is of Yukawa-type, dominated by the graviton exchange, in agreement with earlier findings. On the other hand, at small-$r T$ the $Q\\bar Q$ potential scales as $\\sim (1/r) \\ln (1/rT)$. In the case of $QQ$ potential the 2-form contribution changes sign and becomes repulsive: however, the net $QQ$ potential remains attractive. At large-$r T$ it is dominated by the graviton exchange, while at small-$r T$ the $QQ$ potential becomes Coulomb-like.

Hovhannes R. Grigoryan; Yuri V. Kovchegov

2011-06-23

171

Correction factors for low perturbation in vivo diodes used in the determination of entrance doses in high energy photon beams  

Microsoft Academic Search

Purpose--Low perturbation diodes, with thin buildup caps, can be used to reduce perturbations to the delivered dose. The literature states that additional correction factors are required for low perturbation diodes, however, there are few reported studies into their use. This report measured the dose perturbations and correction factors for diodes with varying buildup cap thicknesses. Methods and materials--Scanditronix EDP15, EDD5,

Ralph Roberts; Amanda Philp

2008-01-01

172

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

SciTech Connect

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 [National Institute of R and D for Physics and Nuclear Engineering-Horia Hulubei, Reactorului 30 St, P.O.BOX MG-6,Magurele, cod 077125 (Romania)

2013-12-16

173

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

174

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

175

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

176

Electron fluence perturbation correction factors for solid state detectors irradiated in megavoltage electron beams.  

PubMed

The perturbation correction factor gamma(p) is defined as the deviation of the absorbed dose in the medium from that predicted by the Spencer-Attix extension of the Bragg-Gray cavity theory where the medium occupies exactly the same volume as the solid state cavity and the electron fluence energy spectrum in the cavity is identical in shape, but not necessarily in magnitude, to that in the medium. The value of gamma(p) has been examined for TL detectors irradiated in megavoltage electron beams (5-20 MeV) using the EGS4 Monte Carlo code. LiF and CaF2 solid state detectors simulated were standard size discs of thickness 1 mm and diameter 3.61 mm irradiated in a water phantom with their centres at d(max) or close to it. Values of gamma(p) for LiF ranged from 0.998 +/- 0.005 to 0.994 +/- 0.005 for electron beams with initial energies of 5 and 20 MeV respectively. For CaF2 the corresponding values were 0.956 +/- 0.006 to 0.989 +/- 0.006 for the same size cavities irradiated at the same depth. EGS4 Monte Carlo simulations demonstrate that the total electron fluence (primary electrons and delta-rays) in these solid state detector materials is significantly different from that in water for the same incident electron energy and depth of irradiation. Thus the Spencer-Attix assumption that the electron fluence energy spectrum in the cavity is identical in shape to that in the medium is violated. Differences in the total electron fluence give rise to electron fluence perturbation correction factors which were up to 5% less than unity for CaF2, indicating a strong violation in this case, but were generally less than 1% for LiF. It is the density of the cavity which perturbs the electron fluence, but it is actually the atomic number differences between the medium and cavity that are responsible for the large electron fluence perturbation correction factors for detectors irradiated close to d(max) because the atomic number affects the change in stopping power with energy. When correction is made for the difference between the electron fluence spectrum in the uniform water phantom and the solid state cavity, the Spencer-Attix cavity equation predicts the dose to water within 0.3% in both clinical and monoenergetic electron beams. Harder's formulation for computing the average mass collision stopping power of water to calcium fluoride, surprisingly, requires perturbation correction factors that are closer to unity than those determined using the Spencer-Attix integrals at depths close to d(max). PMID:10701502

Mobit, P N; Sandison, G A; Nahum, A E

2000-02-01

177

Electron fluence perturbation correction factors for solid state detectors irradiated in megavoltage electron beams  

NASA Astrophysics Data System (ADS)

The perturbation correction factor gamma (p ) is defined as the deviation of the absorbed dose in the medium from that predicted by the Spencer-Attix extension of the Bragg-Gray cavity theory where the medium occupies exactly the same volume as the solid state cavity and the electron fluence energy spectrum in the cavity is identical in shape, but not necessarily in magnitude, to that in the medium. The value of gamma (p ) has been examined for TL detectors irradiated in megavoltage electron beams (5-20 MeV) using the EGS4 Monte Carlo code. LiF and CaF2 solid state detectors simulated were standard size discs of thickness 1 mm and diameter 3.61 mm irradiated in a water phantom with their centres at d max , or close to it. Values of gamma (p ) for LiF ranged from 0.998±0.005 to 0.994±0.005 for electron beams with initial energies of 5 and 20 MeV respectively. For CaF2 the corresponding values were 0.956±0.006 to 0.989±0.006 for the same size cavities irradiated at the same depth. EGS4 Monte Carlo simulations demonstrate that the total electron fluence (primary electrons and delta -rays) in these solid state detector materials is significantly different from that in water for the same incident electron energy and depth of irradiation. Thus the Spencer-Attix assumption that the electron fluence energy spectrum in the cavity is identical in shape to that in the medium is violated. Differences in the total electron fluence give rise to electron fluence perturbation correction factors which were up to 5% less than unity for CaF2 , indicating a strong violation in this case, but were generally less than 1% for LiF. It is the density of the cavity which perturbs the electron fluence, but it is actually the atomic number differences between the medium and cavity that are responsible for the large electron fluence perturbation correction factors for detectors irradiated close to d max because the atomic number affects the change in stopping power with energy. When correction is made for the difference between the electron fluence spectrum in the uniform water phantom and the solid state cavity, the Spencer-Attix cavity equation predicts the dose to water within 0.3% in both clinical and monoenergetic electron beams. Harder's formulation for computing the average mass collision stopping power of water to calcium fluoride, surprisingly, requires perturbation correction factors that are closer to unity than those determined using the Spencer-Attix integrals at depths close to d max .

Mobit, Paul N.; Sandison, George A.; Nahum, Alan E.

2000-02-01

178

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

179

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

NASA Technical Reports Server (NTRS)

The 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. Forecasts are against ERA reanalyses.

Blakenship, Clay; Zavodsky, Bradley; Blackwell, William

2014-01-01

180

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

181

Wall correction factors, P{sub wall}, for parallel-plate ionization chambers  

SciTech Connect

The EGSnrc Monte Carlo user-code CSnrc is used to calculate wall correction factors, P{sub wall}, for parallel-plate ionization chambers in photon and electron beams. A set of P{sub wall} values, computed at the reference depth in water, is presented for several commonly used parallel-plate chambers. These values differ from the standard assumption of unity used by dosimetry protocols by up to 1.7% for clinical electron beams. Calculations also show that P{sub wall} is strongly dependent on the depth of measurement and can vary by as much as 6% for a 6 MeV beam in moving from a depth of d{sub ref} to a depth of R{sub 50}. In photon beams, where there is limited information available regarding P{sub wall} for parallel-plate chambers, CSnrc calculations show P{sub wall} values of up to 2.4% at the reference depth over a range of photon energies. The P{sub wall} values for photon beams are in good agreement with previous estimates of the wall correction but have much lower statistical uncertainties and cover a wider range of photon beam energies.

Buckley, Lesley A.; Rogers, D. W. O. [Ottawa-Carleton Institute of Physics, Carleton University, Ottawa, K1S 5B6 (Canada)

2006-06-15

182

Design and real time implementation of single phase boost power factor correction converter.  

PubMed

This paper presents a real time implementation of the single-phase power factor correction (PFC) AC-DC boost converter. A combination of higher order sliding mode controller based on super twisting algorithm and predictive control techniques are implemented to improve the performance of the boost converter. Due to the chattering effects, the higher order sliding mode control (HOSMC) is designed. Also, the predictive technique is modified taking into account the large computational delays. The robustness of the controller is verified conducting simulation in MATLAB, the results show good performances in both steady and transient states. An experiment is conducted through a test bench based on dSPACE 1104. The experimental results proved that the proposed controller enhanced the performance of the converter under different parameters variations. PMID:25457043

Bouafassa, Amar; Rahmani, Lazhar; Mekhilef, Saad

2014-10-31

183

The calculation of a size correction factor for a whole-body counter  

NASA Astrophysics Data System (ADS)

Whole-Body counting techniques use radiation detectors in order to evaluate the internal exposure from radionuclides. The Whole-Body Counter (WBC) of the Greek Atomic Energy Commission (GAEC) is used for in vivo measurements of workers for routine purposes as well as for the public in case of an emergency. The system has been calibrated using the phantom provided by CANBERRA (RMC phantom) in combination with solid and point sources. Furthermore, four bottle phantoms of different sizes have been used to calibrate the system to measure potassium, 40K, for different sized workers. However, the use of different phantoms in combination with different sources is time consuming and expensive. Moreover, the purchase and construction of the reference standards need specific knowledge. An alternative option would be the use of Monte Carlo simulation. In this study, the Monte Carlo technique has been firstly validated using the 40K measurements of the four phantoms. After the validation of the methodology, the Monte Carlo code, MCNP, has been used with the same simulated geometries (phantom detector) and different sources in order to calculate the efficiency of the system for different photon energies in the four phantoms. The simulation energies correspond to the following radionuclides: 131I, 137Cs, 60Co, and 88Y. A size correction calibration factor has been defined in order to correct the efficiency of the system for the different phantoms and energies for uniform distribution. The factors vary from 0.64 to 1.51 depending on the phantom size and photon energy.

Carinou, E.; Koukouliou, V.; Budayova, M.; Potiriadis, C.; Kamenopoulou, V.

2007-09-01

184

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

185

Output correction factors for nine small field detectors in 6 MV radiation therapy photon beams: A PENELOPE Monte Carlo study  

SciTech Connect

Purpose: To determine detector-specific output correction factors,k{sub Q} {sub c{sub l{sub i{sub n}}}} {sub ,Q} {sub m{sub s{sub r}}} {sup f{sub {sup {sub c}{sub l}{sub i}{sub n}{sub {sup ,f{sub {sup {sub m}{sub s}{sub r}{sub ,}}}}}}}} in 6 MV small photon beams for air and liquid ionization chambers, silicon diodes, and diamond detectors from two manufacturers. Methods: Field output factors, defined according to the international formalism published byAlfonso et al. [Med. Phys. 35, 5179–5186 (2008)], relate the dosimetry of small photon beams to that of the machine-specific reference field; they include a correction to measured ratios of detector readings, conventionally used as output factors in broad beams. Output correction factors were calculated with the PENELOPE Monte Carlo (MC) system with a statistical uncertainty (type-A) of 0.15% or lower. The geometries of the detectors were coded using blueprints provided by the manufacturers, and phase-space files for field sizes between 0.5 × 0.5 cm{sup 2} and 10 × 10 cm{sup 2} from a Varian Clinac iX 6 MV linac used as sources. The output correction factors were determined scoring the absorbed dose within a detector and to a small water volume in the absence of the detector, both at a depth of 10 cm, for each small field and for the reference beam of 10 × 10 cm{sup 2}. Results: The Monte Carlo calculated output correction factors for the liquid ionization chamber and the diamond detector were within about ±1% of unity even for the smallest field sizes. Corrections were found to be significant for small air ionization chambers due to their cavity dimensions, as expected. The correction factors for silicon diodes varied with the detector type (shielded or unshielded), confirming the findings by other authors; different corrections for the detectors from the two manufacturers were obtained. The differences in the calculated factors for the various detectors were analyzed thoroughly and whenever possible the results were compared to published data, often calculated for different accelerators and using the EGSnrc MC system. The differences were used to estimate a type-B uncertainty for the correction factors. Together with the type-A uncertainty from the Monte Carlo calculations, an estimation of the combined standard uncertainty was made, assigned to the mean correction factors from various estimates. Conclusions: The present work provides a consistent and specific set of data for the output correction factors of a broad set of detectors in a Varian Clinac iX 6 MV accelerator and contributes to improving the understanding of the physics of small photon beams. The correction factors cannot in general be neglected for any detector and, as expected, their magnitude increases with decreasing field size. Due to the reduced number of clinical accelerator types currently available, it is suggested that detector output correction factors be given specifically for linac models and field sizes, rather than for a beam quality specifier that necessarily varies with the accelerator type and field size due to the different electron spot dimensions and photon collimation systems used by each accelerator model.

Benmakhlouf, Hamza, E-mail: hamza.benmakhlouf@karolinska.se [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Medical Physics, Karolinska University Hospital, SE-171 76 Stockholm, Sweden, and Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden); Sempau, Josep [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain)] [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Diagonal 647, E-08028, Barcelona (Spain); Andreo, Pedro [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)] [Department of Physics, Medical Radiation Physics, Stockholm University and Karolinska Institute, SE-171 76 Stockholm (Sweden)

2014-04-15

186

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

187

[Characteristics of hemodynamic and skin temperature during application of individually prescribed and corrected magnetotherapeutic regimes (experimental study)].  

PubMed

The objective of this study was to determine functional characteristics of the cardiovascular system and skin temperature believed to adequately reflect its response to the action of an alternating magnetic field (AMF). The estimated parameters included index of cardiovascular regulation and average temperature of the body surface. The time and the skin temperature were determined for each value of regulation index at which AMF action should be terminated. Algorithm for the choice of the AMF treatment regime and its correction depending on body surface temperature and its correlation with the index of cardiovascular regulation. PMID:19886022

Gerasimov, I G; Tedeeva, T A; Simarova, A V

2009-01-01

188

Magnetic-coupled high power factor converter with low line current harmonic distortions for power factor correction and fast output response  

Microsoft Academic Search

A new magnetic-coupled high power factor converter (MCHPFC) with a single switch\\/single stage is proposed. The proposed converter gives good power factor correction, low current harmonic distortions, and tight output voltage regulation. The prototype shows that the IEC555-2 requirements are met satisfactorily with nearly unity power factor. A proposed MCHPFC is particularly suited for low-power-level power supply applications

Gun-Woo Moon; Chung-Wook Roh; Jun-Young Lee; Myung-Joon Choo

1998-01-01

189

Systematic uncertainties in the Monte Carlo calculation of ion chamber replacement correction factors.  

PubMed

In a previous study [Med. Phys. 35, 1747-1755 (2008)], the authors proposed two direct methods of calculating the replacement correction factors (P(repl) or P(cav)P(dis)) for ion chambers by Monte Carlo calculation. By "direct" we meant the stopping-power ratio evaluation is not necessary. The two methods were named as the high-density air (HDA) and low-density water (LDW) methods. Although the accuracy of these methods was briefly discussed, it turns out that the assumption made regarding the dose in an HDA slab as a function of slab thickness is not correct. This issue is reinvestigated in the current study, and the accuracy of the LDW method applied to ion chambers in a 60Co photon beam is also studied. It is found that the two direct methods are in fact not completely independent of the stopping-power ratio of the two materials involved. There is an implicit dependence of the calculated P(repl) values upon the stopping-power ratio evaluation through the choice of an appropriate energy cutoff delta, which characterizes a cavity size in the Spencer-Attix cavity theory. Since the delta value is not accurately defined in the theory, this dependence on the stopping-power ratio results in a systematic uncertainty on the calculated P(repl) values. For phantom materials of similar effective atomic number to air, such as water and graphite, this systematic uncertainty is at most 0.2% for most commonly used chambers for either electron or photon beams. This uncertainty level is good enough for current ion chamber dosimetry, and the merits of the two direct methods of calculating P(repl) values are maintained, i.e., there is no need to do a separate stopping-power ratio calculation. For high-Z materials, the inherent uncertainty would make it practically impossible to calculate reliable P(repl) values using the two direct methods. PMID:19544797

Wang, L L W; La Russa, D J; Rogers, D W O

2009-05-01

190

Intraosseous Delivery of Lentiviral Vectors Targeting Factor VIII Expression in Platelets Corrects Murine Hemophilia A.  

PubMed

Intraosseous (IO) infusion of lentiviral vectors (LVs) for in situ gene transfer into bone marrow may avoid specific challenges posed by ex vivo gene delivery, including, in particular, the requirement of preconditioning. We utilized IO delivery of LVs encoding a GFP or factor VIII (FVIII) transgene directed by ubiquitous promoters (a MND or EF-1?-short element; M-GFP-LV, E-F8-LV) or a platelet-specific, glycoprotein-1b? promoter (G-GFP-LV, G-F8-LV). A single IO infusion of M-GFP-LV or G-GFP-LV achieved long-term and efficient GFP expression in Lineage(-)Sca1(+)c-Kit(+) hematopoietic stem cells and platelets, respectively. While E-F8-LV produced initially high-level FVIII expression, robust anti-FVIII immune responses eliminated functional FVIII in circulation. In contrast, IO delivery of G-F8-LV achieved long-term platelet-specific expression of FVIII, resulting in partial correction of hemophilia A. Furthermore, similar clinical benefit with G-F8-LV was achieved in animals with pre-existing anti-FVIII inhibitors. These findings further support platelets as an ideal FVIII delivery vehicle, as FVIII, stored in ?-granules, is protected from neutralizing antibodies and, during bleeding, activated platelets locally excrete FVIII to promote clot formation. Overall, a single IO infusion of G-F8-LV was sufficient to correct hemophilia phenotype for long term, indicating that this approach may provide an effective means to permanently treat FVIII deficiency. PMID:25655313

Wang, Xuefeng; Shin, Simon C; Chiang, Andy F J; Khan, Iram; Pan, Dao; Rawlings, David J; Miao, Carol H

2015-04-01

191

Temperature corrected kinetic method for the estimation of proton affinities, entropies of protonation and gas phase basicities  

Microsoft Academic Search

The kinetic method provides relative thermochemistry based on the competitive dissociation of mass-selected cluster ions. This dissertation proposes an extension to the current methods of analyzing kinetic method data. This method, termed the temperature corrected kinetic method (TCKM) is more rigorous than the current method and may potentially ease the limitations placed on the choice of reference compounds. In recognition

Jeffry Wayne Danault

2000-01-01

192

Gradient corrections to the kinetic energy density functional of a two-dimensional Fermi gas at finite temperature  

Microsoft Academic Search

We examine the leading order semiclassical gradient corrections to the\\u000anon-interacting kinetic energy density functional of a two dimensional Fermi\\u000agas by applying the extended Thomas-Fermi theory at finite temperature. We find\\u000aa non-zero von Weizs\\\\\\

Brandon P. van Zyl; K. Berkane; K Bencheikh; A. Farrell

2010-01-01

193

Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature  

SciTech Connect

A number of environmental cofactors have been implicated in cataracto-genesis. Two have received the greatest attention: ultraviolet radiation (UVR) and ambient temperature. Unfortunately, both temperature and UVR levels vary similarly with geographical latitude. Careful attention to several more refined physical variables and the geometry of exposure may permit investigators to separate the contributory effects of these two physical agents. This paper briefly reviews the available data, estimates the variation of lenticular temperature with ambient temperature, and provides measurements of short-wavelength (UV-B) UVR exposure to the human eye with different meterological conditions. The study attempts to provide epidemiological investigators with more detailed information necessary to perform more accurate studies of cataract and other ocular pathologies that appear to be related to environmental factors. Ocular UV-B radiation exposure levels were measured at nine locations in the USA near 40 degrees latitude at elevations from sea level to 8000 ft. Terrain reflectance is shown to be much more important than terrain elevation; cloud cover and haze may actually increase ocular exposure; and the value of wearing brimmed hats and spectacles varies with the environment. Several avenues for future research are suggested.

Sliney, D.H.

1986-05-01

194

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

2014-09-01

195

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

196

Irradiated, colour-temperature-corrected accretion discs in ultraluminous X-ray sources  

NASA Astrophysics Data System (ADS)

Although attempts have been made to constrain the stellar types of optical counterparts to ultraluminous X-ray sources (ULXs), the detection of optical variability instead suggests that they may be dominated by reprocessed emission from X-rays which irradiate the outer accretion disc. Here, we report results from a combined X-ray and optical spectral study of a sample of ULXs, which were selected for having broadened disc-like X-ray spectra and known optical counterparts. We simultaneously fit optical and X-ray data from ULXs with a new spectral model of emission from an irradiated, colour-temperature-corrected accretion disc around a black hole, with a central Comptonizing corona. We find that the ULXs require reprocessing fractions of ˜10-3, which is similar to sub-Eddington thermal dominant state black hole binaries (BHBs), but less than has been reported for ULXs with soft ultraluminous X-ray spectra. We suggest that the reprocessing fraction may be due to the opposing effects of self-shielding in a geometrically thick supercritical accretion disc and reflection from far above the central black hole by optically thin material ejected in a natal super-Eddington wind. Then, the higher reprocessing fractions reported for ULXs with wind-dominated X-ray spectra may be due to enhanced scattering on to the outer disc via the stronger wind in these objects. Alternatively, the accretion discs in these ULXs may not be particularly geometrically thick, rather they may be similar in this regard to the thermal dominant state BHBs.

Sutton, Andrew D.; Done, Chris; Roberts, Timothy P.

2014-11-01

197

INTRINSIC COLORS, TEMPERATURES, AND BOLOMETRIC CORRECTIONS OF PRE-MAIN-SEQUENCE STARS  

SciTech Connect

We present an analysis of the intrinsic colors and temperatures of 5-30 Myr old pre-main-sequence (pre-MS) stars using the F0- through M9-type members of nearby, negligibly reddened groups: the ? Cha cluster, the TW Hydra Association, the ? Pic Moving Group, and the Tucana-Horologium Association. To check the consistency of spectral types from the literature, we estimate new spectral types for 52 nearby pre-MS stars with spectral types F3 through M4 using optical spectra taken with the SMARTS 1.5 m telescope. Combining these new types with published spectral types and photometry from the literature (Johnson-Cousins BVI{sub C} , 2MASS JHK{sub S} and WISE W1, W2, W3, and W4), we derive a new empirical spectral type-color sequence for 5-30 Myr old pre-MS stars. Colors for pre-MS stars match dwarf colors for some spectral types and colors, but for other spectral types and colors, deviations can exceed 0.3 mag. We estimate effective temperatures (T {sub eff}) and bolometric corrections (BCs) for our pre-MS star sample through comparing their photometry to synthetic photometry generated using the BT-Settl grid of model atmosphere spectra. We derive a new T {sub eff} and BC scale for pre-MS stars, which should be a more appropriate match for T Tauri stars than often-adopted dwarf star scales. While our new T {sub eff} scale for pre-MS stars is within ?100 K of dwarfs at a given spectral type for stars

Pecaut, Mark J.; Mamajek, Eric E. [University of Rochester, Department of Physics and Astronomy, Rochester, NY 14627-0171 (United States)

2013-09-01

198

Interplay between Raman shift and thermal expansion in graphene: Temperature-dependent measurements and analysis of substrate corrections  

NASA Astrophysics Data System (ADS)

Measurements and calculations have shown significant disagreement regarding the sign and temperature variations of the thermal expansion coefficient (TEC) of graphene ? (T ) . Here we report dedicated Raman scattering experiments conducted for graphene monolayers deposited on silicon nitride substrates and over a broad temperature range extending over 150-800 K. The relation between those measurements for the G band and the graphene TEC, which involves correcting the measured signal from the mismatch contribution of the substrate, is analyzed based on different theoretical candidates for ? (T ) . Contrary to calculations in the quasiharmonic approximation, a many-body potential reparametrized for graphene correctly reproduces experimental data, suggesting that the TEC is more likely to be positive above room temperature.

Linas, S.; Magnin, Y.; Poinsot, B.; Boisron, O.; Förster, G. D.; Martinez, V.; Fulcrand, R.; Tournus, F.; Dupuis, V.; Rabilloud, F.; Bardotti, L.; Han, Z.; Kalita, D.; Bouchiat, V.; Calvo, F.

2015-02-01

199

The value of Seasonal Correction Factors in assessing the health risk from domestic radon: a case study in Northamptonshire, UK.  

PubMed

Following an intensive survey of domestic radon levels in the United Kingdom (UK), the former National Radiological Protection Board (NRPB), now the Radiation Protection Division of the Health Protection Agency (HPA-RPD), established a measurement protocol and promulgated Seasonal Correction Factors applicable to the country as a whole. Radon levels in the domestic built environment are assumed to vary systematically and repeatably during the year, being generally higher in winter. The Seasonal Correction Factors therefore comprise a series of numerical multipliers, which convert a 1-month or 3-month radon concentration measurement, commencing in any month of the year, to an effective annual mean radon concentration. In a recent project undertaken to assess the utility of short-term exposures in quantifying domestic radon levels, a comparative assessment of a number of integrating detector types was undertaken, with radon levels in 34 houses on common geology monitored over a 12-month period using dose-integrating track-etch detectors exposed in pairs (one upstairs, one downstairs) at 1-month and 3-month resolution. Seasonal variability of radon concentrations departed significantly from that expected on the basis of the HPA-RPD Seasonal Correction Factor set, with year-end discontinuities at both 1-month and 3-month measurement resolutions. Following this study, monitoring with electrets was continued in four properties, with weekly radon concentration data now available for a total duration in excess of three and a half years. Analysis of this data has permitted the derivation of reliable local Seasonal Correction Factors. Overall, these are significantly lower than those recommended by HPA-RPD, but are comparable with other results from the UK and from abroad, particularly those that recognise geological diversity and are consequently prepared on a regional rather than a national basis. This finding calls into question the validity of using nationally aggregated Seasonal Correction Factors, especially for shorter exposures, and the universal applicability of these corrections is discussed in detail. PMID:16899293

Denman, A R; Crockett, R G M; Groves-Kirkby, C J; Phillips, P S; Gillmore, G K; Woolridge, A C

2007-01-01

200

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. PMID:24159085

2013-01-01

201

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 0.15 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.

2013-01-01

202

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.

2007-01-01

203

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

204

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

205

27 CFR 30.67 - Table 7, for correction of volume of spirituous liquors to 60 degrees Fahrenheit.  

Code of Federal Regulations, 2011 CFR

...degrees temperature. Where the spirits to be corrected are of an odd temperature, one-half of the difference, if any, between...or if it is also necessary to correct the factor because of odd temperature, to the temperature corrected factor for the...

2011-04-01

206

27 CFR 30.67 - Table 7, for correction of volume of spirituous liquors to 60 degrees Fahrenheit.  

Code of Federal Regulations, 2012 CFR

...degrees temperature. Where the spirits to be corrected are of an odd temperature, one-half of the difference, if any, between...or if it is also necessary to correct the factor because of odd temperature, to the temperature corrected factor for the...

2012-04-01

207

27 CFR 30.67 - Table 7, for correction of volume of spirituous liquors to 60 degrees Fahrenheit.  

Code of Federal Regulations, 2013 CFR

...degrees temperature. Where the spirits to be corrected are of an odd temperature, one-half of the difference, if any, between...or if it is also necessary to correct the factor because of odd temperature, to the temperature corrected factor for the...

2013-04-01

208

27 CFR 30.67 - Table 7, for correction of volume of spirituous liquors to 60 degrees Fahrenheit.  

Code of Federal Regulations, 2010 CFR

...degrees temperature. Where the spirits to be corrected are of an odd temperature, one-half of the difference, if any, between...or if it is also necessary to correct the factor because of odd temperature, to the temperature corrected factor for the...

2010-04-01

209

27 CFR 30.67 - Table 7, for correction of volume of spirituous liquors to 60 degrees Fahrenheit.  

Code of Federal Regulations, 2014 CFR

...degrees temperature. Where the spirits to be corrected are of an odd temperature, one-half of the difference, if any, between...or if it is also necessary to correct the factor because of odd temperature, to the temperature corrected factor for the...

2014-04-01

210

Systematic uncertainties in the Monte Carlo calculation of ion chamber replacement correction factors  

SciTech Connect

In a previous study [Med. Phys. 35, 1747-1755 (2008)], the authors proposed two direct methods of calculating the replacement correction factors (P{sub repl} or p{sub cav}p{sub dis}) for ion chambers by Monte Carlo calculation. By ''direct'' we meant the stopping-power ratio evaluation is not necessary. The two methods were named as the high-density air (HDA) and low-density water (LDW) methods. Although the accuracy of these methods was briefly discussed, it turns out that the assumption made regarding the dose in an HDA slab as a function of slab thickness is not correct. This issue is reinvestigated in the current study, and the accuracy of the LDW method applied to ion chambers in a {sup 60}Co photon beam is also studied. It is found that the two direct methods are in fact not completely independent of the stopping-power ratio of the two materials involved. There is an implicit dependence of the calculated P{sub repl} values upon the stopping-power ratio evaluation through the choice of an appropriate energy cutoff {Delta}, which characterizes a cavity size in the Spencer-Attix cavity theory. Since the {Delta} value is not accurately defined in the theory, this dependence on the stopping-power ratio results in a systematic uncertainty on the calculated P{sub repl} values. For phantom materials of similar effective atomic number to air, such as water and graphite, this systematic uncertainty is at most 0.2% for most commonly used chambers for either electron or photon beams. This uncertainty level is good enough for current ion chamber dosimetry, and the merits of the two direct methods of calculating P{sub repl} values are maintained, i.e., there is no need to do a separate stopping-power ratio calculation. For high-Z materials, the inherent uncertainty would make it practically impossible to calculate reliable P{sub repl} values using the two direct methods.

Wang, L. L. W.; La Russa, D. J.; Rogers, D. W. O. [Ottawa Carleton Institute of Physics, Carleton University, Campus Ottawa, Ottawa, Ontario KIS 5B6 (Canada)

2009-05-15

211

A novel high-efficiency flyback power-factor-correction circuit with regenerative clamping and soft switching  

Microsoft Academic Search

Although most power factor correction (PFC) circuits use the boost topology, the flyback topology does have the advantages of input-output isolation, inrush current limiting and voltage step-down capability. In this paper, the problems associated with flyback PFC circuits are identified. These problems are solved by using a novel regenerative clamping circuit. The circuit topology, analysis, design considerations and experimental results

Kam-Wah Siu; Yim-Shu Lee

2000-01-01

212

A Unity Power Factor Correction Preregulator With Fast Dynamic Response Based on a Low-Cost Microcontroller  

Microsoft Academic Search

Low cost passive power factor correction (PFC) and single-stage PFC converters cannot draw a sinusoidal input current and are only suitable solutions to supply low power levels. PFC preregulators based on the use of a multiplier solve such drawbacks, but a second stage dc-dc converter is needed to obtain fast output voltage dynamics. The output voltage response of PFC preregulators

Diego G. Lamar; Arturo Fernandez; Manuel Arias; Miguel Rodriguez; Javier Sebastian; Marta Maria Hernando

2008-01-01

213

A low frequency AC to high frequency AC inverter with build-in power factor correction and soft-switching  

Microsoft Academic Search

This paper presents a full bridge AC-AC inverter for high frequency power distribution system with power factor correction stage controlled by a unified controller. The proposed inverter has the following features: 1) load independent output voltage with constant frequency and very low total harmonic distortion (THD); 2) soft switching of the full bridge switches for a wide range of input

Wennan Guo; Praveen K. Jain

2004-01-01

214

Correction factors for saturation effects in white light and laser absorption spectroscopy for application to low pressure plasmas  

SciTech Connect

In white light absorption spectroscopy, the broadening of the absorption signal due to the apparatus profile of the spectrometer may lead to an underestimation of the determined density as one measures an apparent optical depth. This is in particular true for high optical depth where saturation effects of the transmitted intensity occur. Provided that the line profile of the absorption line is known, the apparent optical depth effect can be accounted for by introducing a correction factor. The impact of the saturation and the approach of considering the effect are demonstrated for argon and indium lines in low pressure plasmas where correction factors of one order of magnitude or even higher are reached very easily. For the indium line, the hyperfine splitting has been taken into account. In laser absorption, the line profile is resolved. However, the weak but rather broad background emission of the laser diode can cause a saturation signal at the photo diode resulting also in an underestimation of the density obtained from the analysis. It is shown that this can be taken into account by fitting the theoretical line profile to the measured absorption signal which yields also a correction factor. The method is introduced and demonstrated at the example of the cesium resonance line including the hyperfine splitting. Typical correction factors around two are obtained for the cesium ground state density at conditions of a low pressure negative hydrogen ion source in which cesium is evaporated to enhance the negative ion production.

Briefi, S. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Wimmer, C.; Fantz, U. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2012-05-15

215

A novel, empirical equation — Based shunt active filter for harmonic elimination and power factor correction, using a modified PSO algorithm  

Microsoft Academic Search

This paper presents a novel approach for harmonic elimination and power factor correction (PFC) in a single phase AC-DC rectifier system using a shunt Active Power Filter (APF). The DC output of the rectifier is further regulated using a Buck Converter. The active filter topology is based on a single-phase voltage source inverter with four IGBT switches. The proposed approach

Harish S. Krishnamoorthy; Manoj K. Vadali; Prahlad Supeda

2011-01-01

216

Factors affecting characterization of bulk high-temperature superconductors  

SciTech Connect

Three major factors affect the characterization of bulk high-temperature superconductors in terms of their levitation properties during interaction with permanent magnets. First, the appropriate parameter for the permanent magnet is internal magnetization, not the value of the magnetic field measured at the magnet`s surface. Second, although levitation force grows with superconductor thickness and surface area, for a given permanent magnet size, comparison of levitation force between samples is meaningful when minimum values are assigned to the superconductor size parameters. Finally, the effect of force creep must be considered when time-averaging the force measurements. In addition to levitational force, the coefficient of friction of a levitated rotating permanent magnet may be used to characterize the superconductor.

Hull, J.R. [Argonne National Lab., IL (United States). Energy Technology Div.

1997-11-01

217

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

218

Temperature factor for magnetic instability conditions of type - II superconductors  

NASA Astrophysics Data System (ADS)

The macroscopic development of interrelated electrodynamics and thermal states taking place both before and after instability onset in type-II superconductors are studied using the critical state and the flux creep concepts. The physical mechanisms of the non-isothermal formation of the critical state are discussed solving the set of unsteady thermo-electrodynamics equations taking into consideration the unknown moving penetration boundary of the magnetic flux. To make it, the numerical method, which allows to study diffusion phenomena with unknown moving phase-two boundary, is developed. The corresponding non-isothermal flux jump criteria are written. It is proved for the first time that, first, the diffusion phenomena in superconductors have the fission-chain-reaction nature, second, the stability conditions, losses in superconductor and its stable overheating before instability onset are mutually dependent. The results are compared with those following from the existing magnetic instability theory, which does not take into consideration the stable temperature increase of superconductor before the instability onset. It is shown that errors of isothermal approximation are significant for modes closed to adiabatic ones. Therefore, the well-known adiabatic flux jump criterion limits the range of possible stable superconducting states since a correct determination of their stability states must take into account the thermal prehistory of the stable magnetic flux penetration. As a result, the calculation errors in the isothermal approximation will rise when the sweep rate of an external magnetic field or the size of the superconductor’s cross-sectional area increase. The basic conclusions formulated in the framework of the critical state model are verified comparing the experimental results and the numerical analysis of the stability conditions and the temperature dynamics of the helicoid-type superconducting current-carrying element having real voltage-current characteristic. On the whole, the non-isothermal stability conditions expand the existence of allowable stable superconducting states. The non-isothermal approximation permits also to link the theories of the losses, the magnetic instability and the thermal stabilization of superconductors, which are independently developed.

Romanovskii, V.

2014-10-01

219

Quantum corrections to temperature dependent electrical conductivity of ZnO thin films degenerately doped with Si  

SciTech Connect

ZnO thin films degenerately doped with Si (Si{sub x}Zn{sub 1?x}O) in the concentrations range of ?0.5% to 5.8% were grown by sequential pulsed laser deposition on sapphire substrates at 400?°C. The temperature dependent resistivity measurements in the range from 300 to 4.2?K revealed negative temperature coefficient of resistivity (TCR) for the 0.5%, 3.8%, and 5.8% doped Si{sub x}Zn{sub 1?x}O films in the entire temperature range. On the contrary, the Si{sub x}Zn{sub 1?x}O films with Si concentrations of 1.0%, 1.7%, and 2.0% showed a transition from negative to positive TCR with increasing temperature. These observations were explained using weak localization based quantum corrections to conductivity.

Das, Amit K., E-mail: amitkrdh@gmail.com; Ajimsha, R. S.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Center for Advanced Technology, Indore 452 013 (India)

2014-01-27

220

Quantum corrections to temperature dependent electrical conductivity of ZnO thin films degenerately doped with Si  

NASA Astrophysics Data System (ADS)

ZnO thin films degenerately doped with Si (SixZn1-xO) in the concentrations range of ˜0.5% to 5.8% were grown by sequential pulsed laser deposition on sapphire substrates at 400 °C. The temperature dependent resistivity measurements in the range from 300 to 4.2 K revealed negative temperature coefficient of resistivity (TCR) for the 0.5%, 3.8%, and 5.8% doped SixZn1-xO films in the entire temperature range. On the contrary, the SixZn1-xO films with Si concentrations of 1.0%, 1.7%, and 2.0% showed a transition from negative to positive TCR with increasing temperature. These observations were explained using weak localization based quantum corrections to conductivity.

Das, Amit K.; Ajimsha, R. S.; Kukreja, L. M.

2014-01-01

221

Strong temperature dependence of the Hall factor of p-type CoSb3: A re-analysis incorporating band nonparabolicity  

NASA Astrophysics Data System (ADS)

The Hall factor has been calculated as a function of temperature for p-type CoSb3 samples reported by Hui et al. [J. Appl. Phys. 115, 103704 (2014)] in addition to those reported by Caillat et al. [J. Appl. Phys. 80, 4442 (1996)], incorporating the valence band nonparabolicity. For the nominally undoped p-type samples, reported by Caillat et al., the Hall factor was calculated to increase with temperature from about 1.6 around room temperature to about as large as 5 at 900 K. Owing to the incorporation of the Hall factor, the net acceptor concentration has been corrected to be larger by about 1.6 times. Furthermore, due to the strong temperature dependence of the Hall factor, the band-gap energy deduced through fitting the temperature dependence of the Hall coefficient has been corrected to be smaller by about 0.03 eV than the values deduced when assuming a constant Hall factor of unity. It has also been shown that, even when the temperature dependence of the Hall factor is considered, the incorporation of the second valence band into the calculation is necessary to explain the anomalous increase of the Hall coefficient with temperature in the Sn-doped p-type CoSb3 sample reported by Hui et al.

Kajikawa, Y.

2015-02-01

222

Correction factors for on-line microprobe analysis of multielement alloy systems  

NASA Technical Reports Server (NTRS)

An on-line correction technique was developed for the conversion of electron probe X-ray intensities into concentrations of emitting elements. This technique consisted of off-line calculation and representation of binary interaction data which were read into an on-line minicomputer to calculate variable correction coefficients. These coefficients were used to correct the X-ray data without significantly increasing computer core requirements. The binary interaction data were obtained by running Colby's MAGIC 4 program in the reverse mode. The data for each binary interaction were represented by polynomial coefficients obtained by least-squares fitting a third-order polynomial. Polynomial coefficients were generated for most of the common binary interactions at different accelerating potentials and are included. Results are presented for the analyses of several alloy standards to demonstrate the applicability of this correction procedure.

Unnam, J.; Tenney, D. R.; Brewer, W. D.

1977-01-01

223

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

SciTech Connect

This article describes four methods of calculating the replacement correction factor, P{sub repl} (or the product p{sub cav}p{sub 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 0.1% when appropriate calculation parameters are selected. The depth dependence of P{sub repl} for the NACP02 plane-parallel chamber has been calculated in both 6 and 18 MeV electron beams. At the reference depth (0.6R{sub 50}-0.1 cm) P{sub 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{sub repl} is 1.0010. P{sub repl} is also calculated for the NACP02 chamber and a Farmer chamber (diameter 6 mm) at a depth of 5 cm in a {sup 60}Co photon beam, giving values of 1.0063 and 0.9964, respectively. For the Farmer chamber, P{sub 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{sub repl} for cylindrical chambers in photon beams. The nonunity values of P{sub repl} for plane-parallel chambers in lower energy electron beams imply a variety of values used in dosimetry protocols must be reassessed.

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

2008-05-15

224

Implicit temperature-correction-based immersed-boundary thermal lattice Boltzmann method for the simulation of natural convection  

NASA Astrophysics Data System (ADS)

In the present paper, we apply the implicit-correction method to the immersed-boundary thermal lattice Boltzmann method (IB-TLBM) for the natural convection between two concentric horizontal cylinders and in a square enclosure containing a circular cylinder. The Chapman-Enskog multiscale expansion proves the existence of an extra term in the temperature equation from the source term of the kinetic equation. In order to eliminate the extra term, we redefine the temperature and the source term in the lattice Boltzmann equation. When the relaxation time is less than unity, the new definition of the temperature and source term enhances the accuracy of the thermal lattice Boltzmann method. The implicit-correction method is required in order to calculate the thermal interaction between a fluid and a rigid solid using the redefined temperature. Simulation of the heat conduction between two concentric cylinders indicates that the error at each boundary point of the proposed IB-TLBM is reduced by the increment of the number of Lagrangian points constituting the boundaries. We derive the theoretical relation between a temperature slip at the boundary and the relaxation time and demonstrate that the IB-TLBM requires a small relaxation time in order to avoid temperature distortion around the immersed boundary. The streamline, isotherms, and average Nusselt number calculated by the proposed method agree well with those of previous numerical studies involving natural convection. The proposed IB-TLBM improves the accuracy of the boundary conditions for the temperature and velocity using an adequate discrete area for each of the Lagrangian nodes and reduces the penetration of the streamline on the surface of the body.

Seta, Takeshi

2013-06-01

225

Implicit temperature-correction-based immersed-boundary thermal lattice Boltzmann method for the simulation of natural convection.  

PubMed

In the present paper, we apply the implicit-correction method to the immersed-boundary thermal lattice Boltzmann method (IB-TLBM) for the natural convection between two concentric horizontal cylinders and in a square enclosure containing a circular cylinder. The Chapman-Enskog multiscale expansion proves the existence of an extra term in the temperature equation from the source term of the kinetic equation. In order to eliminate the extra term, we redefine the temperature and the source term in the lattice Boltzmann equation. When the relaxation time is less than unity, the new definition of the temperature and source term enhances the accuracy of the thermal lattice Boltzmann method. The implicit-correction method is required in order to calculate the thermal interaction between a fluid and a rigid solid using the redefined temperature. Simulation of the heat conduction between two concentric cylinders indicates that the error at each boundary point of the proposed IB-TLBM is reduced by the increment of the number of Lagrangian points constituting the boundaries. We derive the theoretical relation between a temperature slip at the boundary and the relaxation time and demonstrate that the IB-TLBM requires a small relaxation time in order to avoid temperature distortion around the immersed boundary. The streamline, isotherms, and average Nusselt number calculated by the proposed method agree well with those of previous numerical studies involving natural convection. The proposed IB-TLBM improves the accuracy of the boundary conditions for the temperature and velocity using an adequate discrete area for each of the Lagrangian nodes and reduces the penetration of the streamline on the surface of the body. PMID:23848803

Seta, Takeshi

2013-06-01

226

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

NASA Astrophysics Data System (ADS)

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 mm3 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 cm3 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.

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

2012-05-01

227

Møller-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 Møller-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

228

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

229

Development of correction factors for landfill gas emission model suiting Indian condition to predict methane emission from landfills.  

PubMed

Methane emission from landfill gas emission (LandGEM) model was validated through the results of laboratory scale biochemical methane potential assay. Results showed that LandGEM model over estimates methane (CH4) emissions; and the true CH4 potential of waste depends on the level of segregation. Based on these findings, correction factors were developed to estimate CH4 emission using LandGEM model especially where the level of segregation is negligible or does not exist. The correction factors obtained from the study were 0.94, 0.13 and 0.74 for food waste, mixed un-segregated municipal solid waste (MSW) and vegetable wastes, respectively. PMID:24685512

Sil, Avick; Kumar, Sunil; Wong, Jonathan W C

2014-09-01

230

Development of Self-Correcting Algorithms for Complete Failure of Supply Air Temperature Sensors  

E-print Network

and diagnosis (FDD) of heating, ventilation and air conditioning (HVAC) building equipment ? physical models ? analytical models ? methods driven by performance data ? artificial intelligence ? statistical techniques 2 ESL-IC-13-10-47 Proceedings...: August and September 2012 ESL-IC-13-10-47 Proceedings of the 13th International Conference for Enhanced Building Operations, Montreal, Quebec, October 8-11, 2013 Self-correction of HVAC controls ? proposed approach 9 2. Algorithm Development (cont...

Monfet, D.; Choiniere, D.; Padilla, M.

2013-01-01

231

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

232

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

René P. T. Bascopé; Carlos G. C. Branco; Cícero M. T. Cruz; Gilberto F. S. Filho; Luiz D. S. Bezerra

2009-01-01

233

Looking for simple correction functions between the mean radiant temperature from the "standard black globe" and the "six-directional" techniques in Taiwan  

NASA Astrophysics Data System (ADS)

Mean radiant temperature (T mrt) values were calculated and compared to each other in Taiwan based on the six-directional and globe techniques. In the case of the six-directional technique (measurements with pyranometers and pyrgeometers), two different T mrt values were calculated: one representing the radiation load on a standing man [T mrt(st)] and the other which refers to a spherical reference shape [T mrt(sp)]. Moreover, T mrt(T g ) was obtained through the globe thermometer technique applying the standard black globe. Comparing T mrt values based on the six-directional technique but with different reference shapes revealed that the difference was always in the +/-5 °C domain. Of the cases, 75 % fell into the +/-5 °C Delta Tmrt range when we compared different techniques with similar reference shapes [T mrt(sp) and T mrt(T g )] and only 69 % when we compared the different techniques with different reference shapes [T mrt(st) and T mrt(T g )]. Based on easily accessible factors, simple correction functions were determined to make the T mrt(T g ) values of already existing outdoor thermal comfort databases comparable with other databases which involve sixdirectional T mrt. The corrections were conducted directly between the T mrt(T g ) and T mrt(sp) values and also indirectly, i.e., by using the values of T g to reduce the differences between T mrt(sp) and T mrt(T g ). Both correction methods resulted in considerable improvement and reduced the differences between the T mrt(sp) and the T mrt(T g ) values. However, validations with an independent database from Hungary revealed that it is not suggested to apply the correction functions under totally different background climate conditions.

Kántor, Noémi; Kovács, Attila; Lin, Tzu-Ping

2014-07-01

234

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

235

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.

236

Light and Temperature: Key Factors Affecting Walleye Abundance and Production  

Microsoft Academic Search

We used published information to determine optimum light and temperature conditions for walleye Sander vitreus (formerly Stizostedion vitreum) and then applied this simple niche definition to predict how water clarity, temperature, and bathymetry affect walleye habitat availability. Our model calculated thermal–optical habitat area (TOHA), the benthic area of a lake that supplies optimum light, and temperature conditions for walleye during

Nigel P. Lester; Alan J. Dextrase; Robert S. Kushneriuk; Michael R. Rawson; Phil A. Ryan

2004-01-01

237

Correction Factors Applied to Finger Dosimetry: A Theoretical Assessment of Appropriate Values for Use in Handling Radiopharmaceuticals  

SciTech Connect

United States Nuclear Regulatory Commission (USNRC) regulations limit the dose to the skin to 500 mSv per year. This is also the dose limit recommended by the International Commission on Radiological Protection (ICRP). The operational quantity recommended by ICRP for quantifying dose to the skin is the personal dose equivalent, Hp(0.07) and is identical to NRC s shallow dose equivalent, Hs, also measured at a skin depth of 7 mg cm 2. However, whereas ICRP recommends averaging the dose to the skin over an area of 1 cm2 regardless of the size of the exposed area of skin, USNRC requires the shallow dose equivalent to be averaged over 10 cm2. To monitor dose to the skin of the hands of workers handling radioactive materials and particularly in radiopharmaceutical manufacturing facilities, which is the focus of this work, workers are frequently required to wear finger ring dosimeters. The dosimeters monitor the dose at the location of the sensitive element, but this is not the dose required to show compliance (i.e., the dose averaged over the highest exposed contiguous 10 cm2 of skin). Therefore, it may be necessary to apply a correction factor that enables estimation of the required skin dose from the dosimeter reading. This work explored the effects of finger ring placement and of the geometry of the radioactive materials being handled by the worker on the relationship between the dosimeter reading and the desired average dose. A mathematical model of the hand was developed for this purpose that is capable of positioning the fingers in any desired grasping configuration, thereby realistically modeling manipulation of any object. The model was then used with the radiation transport code MCNP to calculate the dose distribution on the skin of the hand when handling a variety of radioactive vials and syringes, as well as the dose to the dosimeter element. Correction factors were calculated using the results of these calculations and examined for any patterns that may be useful in establishing an appropriate correction factor for this type of work. It was determined that a correction factor of one applied to the dosimeter reading, with the dosimeter placed at the base of the middle finger, provides an adequate estimate of the required average dose during a monitoring period for most commonly encountered geometries. Different correction factors may be required for exceptional or unusual source geometries and must be considered on a case-by-case basis.

Sherbini, Sami [NRC; Ilas, Dan [ORNL; Eckerman, Keith F [ORNL; DeCicco, Joseph [NRC

2011-01-01

238

A new method for both harmonic voltage and harmonic current suppression and power factor correction in industrial power systems  

SciTech Connect

This paper proposes a new method for designing a group of single tuned filters for both harmonic current injection suppression and harmonic voltage distortion reduction and power factor correction. The proposed method is based on three purposes: (1) reduction of harmonic voltage distortion in the source terminals to an acceptable level, (2) suppression of harmonic current injection in the source terminals to an acceptable level, (3) improvement of power factor at the source terminals. To determine the size of the capacitor in a group of single tuned filters, three new NLP mathematical formulations will be introduced. The first is to suppress harmonic current injection within an acceptable level. The second is to minimize the fundamental reactive power output while reducing harmonic voltage distortion to an acceptable level. The third is to determine an optimal assignment of reactive power output based on the results of harmonic voltage reduction and power factor correction. This new method has been demonstrated for designing a group of single tuned filters and its validity has been successfully confirmed through numerical simulation in a 35 KV industrial power system. The proposed method can efficiently provide an optimal coordination in a group of single tuned filters relating to suppressing harmonic current injection, reducing harmonic voltage distortion and improving power factor.

Cheng, H. [Shanghai Jiao Tong Univ. (China). Dept. of Electrical Power Engineering; Sasaki, Hiroshi; Yorino, Naoto [Hiroshima Univ., Higashi-Hiroshima (Japan). Dept. of Electrical Engineering

1995-12-31

239

Impacts of climate change on temperature, precipitation and hydrology in Finland - studies using bias corrected Regional Climate Model data  

NASA Astrophysics Data System (ADS)

Assessment of climate change impacts on climate and hydrology on catchment scale requires reliable information about the average values and climate fluctuations of the past, present and future. Regional Climate Models (RCMs) used in impact studies often produce biased time series of meteorological variables. In this study bias correction of RCM temperature and precipitation for Finland is carried out using different versions of distribution based scaling (DBS) method. The DBS adjusted RCM data is used as input of a hydrological model to simulate changes in discharges in four study catchments in different parts of Finland. The annual mean discharges and seasonal variation simulated with the DBS adjusted temperature and precipitation data are sufficiently close to observed discharges in the control period (1961-2000) and produce more realistic projections for mean annual and seasonal changes in discharges than the uncorrected RCM data. Furthermore, with most scenarios the DBS method used preserves the temperature and precipitation trends of the uncorrected RCM data during 1961-2100. However, if the biases in the mean or the SD of the uncorrected temperatures are large, significant biases after DBS adjustment may remain or temperature trends may change, increasing the uncertainty of climate change projections. The DBS method influences especially the projected seasonal changes in discharges and the use of uncorrected data can produce unrealistic seasonal discharges and changes. The projected changes in annual mean discharges are moderate or small, but seasonal distribution of discharges will change significantly.

Olsson, T.; Jakkila, J.; Veijalainen, N.; Backman, L.; Kaurola, J.; Vehviläinen, B.

2015-03-01

240

Temperature calibration and correction report for PMEL trace gas cruises 1986-1989. Technical memo  

SciTech Connect

Present methods for evaluating the in situ concentrations of gases in surface seawater require accurate temperature measurements. Temperature data from each of 5 PMEL cruises over the years 1986 to 1989 are discussed independently to describe the different types of data available and the methods of analysis. The seawater warming between the inlet and the equilibrator is shown for each cruise as calculated by a point-by-point method and a regression method, and both methods are discussed. The data are given in an accompanying diskette in ASCII format.

Murphy, P.P.; Cosca, C.; Lee, D.C.; Feely, R.A.

1993-02-01

241

Review of mathematics, numerical factors, and corrections for dark matter experiments based on elastic nuclear recoil  

Microsoft Academic Search

We present a systematic derivation and discussion of the practical formulae needed to design and interpret direct searches for nuclear recoil events caused by hypothetical weakly interacting dark matter particles. Modifications to the differential energy spectrum arise from the Earth's motion, recoil detection efficiency, instrumental resolution and threshold, multiple target elements, spin-dependent and coherent factors, and nuclear form factor. We

J. D. Lewin; P. F. Smith

1996-01-01

242

Phenotypic Correction of Hemophilia A by Ectopic Expression of Activated Factor VII in Platelets  

Microsoft Academic Search

Platelets are receiving much attention as novel target cells to secrete a coagulation factor for hemophilia gene therapy. In order to extend the application of platelet-directed gene therapy, we examined whether ectopic expression of activated factor VII (FVIIa) in platelets would result in an efficient bypass therapy to induce sufficient thrombin generation on platelet surfaces in mice with hemophilia A.

Tsukasa Ohmori; Akira Ishiwata; Yuji Kashiwakura; Seiji Madoiwa; Katsuyuki Mitomo; Hidenori Suzuki; Mamoru Hasegawa; Jun Mimuro; Yoichi Sakata

2008-01-01

243

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

244

Finite Temperature QED: Non-Cancellation of Infrared Divergencies and Thermal Corrections to the Electron Magnetic Moment  

E-print Network

In this work quantum electrodynamics at T > 0 is considered. For this purpose we use thermo field dynamics and the causal approach to quantum field theory according to Epstein and Glaser, the latter being a rigorous method to avoid the well-known ultraviolet divergencies of quantum field theory. It will be shown that the theory is infrared divergent if the usual scattering states are used. The same is true if we use more general mixed states. This is in contradiction to the results established in the literature, and we will point out why these earlier approaches fail to describe the infrared behaviour correctly. We also calculate the thermal corrections to the electron magnetic moment in the low temperature approximation k_B T q. We reproduce one of the different results reported up to now in literature. In the low temperature approximation infrared finiteness is recovered in a very straightforward way: In contrast to the literature we do not have to introduce a thermal Dirac equation or thermal spinors.

Adrian Muller

2000-06-28

245

Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature  

Microsoft Academic Search

A number of environmental cofactors have been implicated in cataracto-genesis. Two have received the greatest attention: ultraviolet radiation (UVR) and ambient temperature. Unfortunately, both temperature and UVR levels vary similarly with geographical latitude. Careful attention to several more refined physical variables and the geometry of exposure may permit investigators to separate the contributory effects of these two physical agents. This

Sliney

1986-01-01

246

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

247

Factors influencing the accuracy of high temperature sag calculations  

Microsoft Academic Search

Increased thermal ratings of transmission lines are important for operators of transmission lines. While scientific knowledge of thermal phenomena has advanced substantially in the past two decades, little has been done to improve the understanding of the practical effects of the most important factors for practical transmission engineers. This report studies the impact of various factors on line rating by

T. O. Seppa

1994-01-01

248

Accurately evaluating Young's modulus of polymers through nanoindentations: A phenomenological correction factor to the Oliver and Pharr procedure  

NASA Astrophysics Data System (ADS)

The Oliver and Pharr [J. Mater. Res. 7, 1564 (1992)] procedure is a widely used tool to analyze nanoindentation force curves obtained on metals or ceramics. Its application to polymers is, however, difficult, as Young's moduli are commonly overestimated mainly because of viscoelastic effects and pileup. However, polymers spanning a large range of morphologies have been used in this work to introduce a phenomenological correction factor. It depends on indenter geometry: sets of calibration indentations have to be performed on some polymers with known elastic moduli to characterize each indenter.

Tranchida, Davide; Piccarolo, Stefano; Loos, Joachim; Alexeev, Alexander

2006-10-01

249

Extracting High Temperature Event radiance from satellite images and correcting for saturation using Independent Component Analysis  

E-print Network

.Barnie@opgc.univ-bpclermont.fr (C. Oppenheimer). http://dx.doi.org/10.1016/j.rse.2014.10.023 0034-4257/© 2014 The Authors. Published by Elsevier Incyon, & Nordberg, 1965; 1979; Harris et al., 1997; al., 2002; Kaufman et al., HTE processes can be explicitly modelled, for instance... including back- ground surface temperature as a free parameter in subpixel thermal unmixing (although this is usually assumed a priori, e.g. Oppenheimer,Glaze, Francis, & Rothery, 1989; Hanel et al., Oppenheimer, 1991), wildfires (e.g. Justice et1...

Barnie, Talfan; Oppenheimer, Clive

2014-12-01

250

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

251

Proton form-factor dependence of the finite-size correction to the Lamb shift in muonic hydrogen  

E-print Network

The measurement of the 2P^{F=2}_{3/2} to 2S^{F=1}_{1/2} transition in muonic hydrogen by Pohl et al. and subsequent analysis has led to the conclusion that the rms radius of the proton differs from the accepted (CODATA) value by approximately 4%, corresponding to a 4.9 sigma discrepancy. We investigate the finite-size effects - in particular the dependence on the shape of the proton electric form-factor - relevant to this transition using bound-state QED with nonperturbative, relativistic Dirac wave-functions for a wide range of idealised charge-distributions and a parameterization of experimental data in order to comment on the extent to which the perturbation-theory analysis which leads to the above conclusion can be confirmed. We find no statistically significant dependence of this correction on the shape of the proton form-factor.

J. D. Carroll; A. W. Thomas; J. Rafelski; G. A. Miller

2011-08-12

252

Proton form-factor dependence of the finite-size correction to the Lamb shift in muonic hydrogen  

E-print Network

The measurement of the 2P^{F=2}_{3/2} to 2S^{F=1}_{1/2} transition in muonic hydrogen by Pohl et al. and subsequent analysis has led to the conclusion that the rms radius of the proton differs from the accepted (CODATA) value by approximately 4%, corresponding to a 4.9 sigma discrepancy. We investigate the finite-size effects - in particular the dependence on the shape of the proton electric form-factor - relevant to this transition using bound-state QED with nonperturbative, relativistic Dirac wave-functions for a wide range of idealised charge-distributions and a parameterization of experimental data in order to comment on the extent to which the perturbation-theory analysis which leads to the above conclusion can be confirmed. We find no statistically significant dependence of this correction on the shape of the proton form-factor.

Carroll, J D; Rafelski, J; Miller, G A

2011-01-01

253

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

NASA Astrophysics Data System (ADS)

Plastic scintillation detectors (PSDs) have many advantages over other detectors in small field dosimetry due to their high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs undergo a quenching effect which makes the signal level reduced significantly when the detector is close to the 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, ?0.5 mm × 4 mm) 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 the 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.

2012-12-01

254

Influence of unfavourable environmental factors upon health of workers and correction of resultant alterations  

Microsoft Academic Search

Intensified formation of free radicals is one of the most important unfavourable consequences of factors of industry acting upon human organism. Under physiological conditions, antioxidative system preserves from harmful influence of free radicals. To avoid a disturbing influence of oxidative stress upon the processes of human homeosthasis, additional quantities of antioxidants are indispensable. Dynamics of alterations of markers of oxidative

Algirdas Juozulynas; Antanas Jurgelenas

2005-01-01

255

A simple strategy of power factor correction based on low-end MCU  

Microsoft Academic Search

A low-end MCU base power factor corrector (PFC) is proposed in this paper. Due to green power issue, PFC is more important, but need an extra controller to achieve. However, in most electric equipments and appliances, the MCU is used to accomplish key functions or handle user interface. The structure and control strategy proposed in this paper is based on

Chung-Wen Hung; Jhih-Han Chen; Li-Sheng Chang; Cheng-Han Li

2010-01-01

256

Single current sensor control for single-phase active power factor correction  

Microsoft Academic Search

This paper presents the realization of a boost-type active power factor corrector (APFC) using a single current sensor to sense the inductor current for input current shaping and output voltage regulation. Neither input voltage nor output voltage sensing is needed. The sensed inductor current is used for two main functions. The first one is for comparing with a sawtooth signal

D.-Y. Qiu; S.-C. Yip; H. S. H. Chung; S. Y. R. Hui

2002-01-01

257

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

258

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...

259

Mechanical quality factor of a sapphire fiber at cryogenic temperatures  

E-print Network

A mechanical quality factor of $1.1 \\times 10^{7}$ was obtained for the 199 Hz bending vibrational mode in a monocrystalline sapphire fiber at 6 K. Consequently, we confirm that pendulum thermal noise of cryogenic mirrors used for gravitational wave detectors can be reduced by the sapphire fiber suspension.

T. Uchiyama; T. Tomaru; D. Tatsumi; S. Miyoki; M. Ohashi; K. Kuroda; T. Suzuki; A. Yamamoto; T. Shintomi

2000-07-27

260

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

261

Predictive factors for perioperative blood transfusion in surgeries for correction of idiopathic, neuromuscular or congenital scoliosis  

PubMed Central

OBJECTIVE: To evaluate the association of clinical and demographic variables in patients requiring blood transfusion during elective surgery to treat scoliosis with the aim of identifying markers predictive of the need for blood transfusion. METHODS: Based on the review of medical charts at a public university hospital, this retrospective study evaluated whether the following variables were associated with the need for red blood cell transfusion (measured by the number of packs used) during scoliosis surgery: scoliotic angle, extent of arthrodesis (number of fused levels), sex of the patient, surgery duration and type of scoliosis (neuromuscular, congenital or idiopathic). RESULTS: Of the 94 patients evaluated in a 55-month period, none required a massive blood transfusion (most patients needed less than two red blood cell packs). The number of packs was not significantly associated with sex or type of scoliosis. The extent of arthrodesis (r?=?0.103), surgery duration (r?=?0.144) and scoliotic angle (r?=?0.004) were weakly correlated with the need for blood transfusion. Linear regression analysis showed an association between the number of spine levels submitted to arthrodesis and the volume of blood used in transfusions (p?=?0.001). CONCLUSION: This study did not reveal any evidence of a significant association between the need for red blood cell transfusion and scoliotic angle, sex or surgery duration in scoliosis correction surgery. Submission of more spinal levels to arthrodesis was associated with the use of a greater number of blood packs. PMID:25518018

Cristante, Alexandre Fogaça; Borges, Paulo Alvim; Barbosa, Angelo Roberto; Letaif, Olavo Biraghi; Marcon, Raphael Martus; de Barros-Filho, Tarcisio Eloy Pessoa

2014-01-01

262

Transcription factor genes Smad4 and Gata4 cooperatively regulate cardiac valve development. [corrected  

PubMed

We report that the dominant human missense mutations G303E and G296S in GATA4, a cardiac-specific transcription factor gene, cause atrioventricular septal defects and valve abnormalities by disrupting a signaling cascade involved in endocardial cushion development. These GATA4 missense mutations, but not a mutation causing secundum atrial septal defects (S52F), demonstrated impaired protein interactions with SMAD4, a transcription factor required for canonical bone morphogenetic protein/transforming growth factor-? (BMP/TGF-?) signaling. Gata4 and Smad4 genetically interact in vivo: atrioventricular septal defects result from endothelial-specific Gata4 and Smad4 compound haploinsufficiency. Endothelial-specific knockout of Smad4 caused an absence of valve-forming activity: Smad4-deficient endocardium was associated with acellular endocardial cushions, absent epithelial-to-mesenchymal transformation, reduced endocardial proliferation, and loss of Id2 expression in valve-forming regions. We show that Gata4 and Smad4 cooperatively activated the Id2 promoter, that human GATA4 mutations abrogated this activity, and that Id2 deficiency in mice could cause atrioventricular septal defects. We suggest that one determinant of the phenotypic spectrum caused by human GATA4 mutations is differential effects on GATA4/SMAD4 interactions required for endocardial cushion development. PMID:21330551

Moskowitz, Ivan P; Wang, Jun; Peterson, Michael A; Pu, William T; Mackinnon, Alexander C; Oxburgh, Leif; Chu, Gerald C; Sarkar, Molly; Berul, Charles; Smoot, Leslie; Robertson, Elizabeth J; Schwartz, Robert; Seidman, Jonathan G; Seidman, Christine E

2011-03-01

263

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

264

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 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. To understand the power flow through the system this paper presents a novel approach to the system model and the impact of different control parameters on the load power. The implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation is also discussed.

Chinthavali, Madhu Sudhan [ORNL] [ORNL; Onar, Omer C [ORNL] [ORNL; Miller, John M [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL

2013-01-01

265

Well correction factors for three-dimensional reservoir simulation with nonsquare grid blocks and anisotropic permeability  

E-print Network

permeability, kh Viscosity of fluid, p Total compressibility, ct Formation volume factor, B Producing rate, q Penetration ratio, hp/ht Permeability ratio, kz/kh 0. 25 1024 ft 50. 0 0. 20 50. 0 md 0. 37 cp 4. 28 E-6 psi 0. 979 RB/STB 5000. STB.... 3388 27. 9631 0. 4. 2842 8. 3827 15. 7067 31. 0090 0. 4. 7397 9. 2929 17. 5225 35. 0652 0. 5. 0848 9. 9828 18. 8996 38. 1479 35 38 25 15 ? KZ/KH = 1. 8 KZ/KH = 8. 5 KZ/KH = 8. 2 KZ/KH = 8. 1 8 1 2 3 4 5 6 7 6 9 H'1/HP - 1 PIE...

Kim, Dukmin

1988-01-01

266

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 et al. 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, Fabián; Lallena, Antonio M

2013-03-01

267

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

268

Correction of hypertension by normalization of endothelial levels of fibroblast growth factor and nitric oxide synthase in spontaneously hypertensive rats.  

PubMed Central

Acidic and basic fibroblast growth factors (FGFs) share a wide range of diverse biological activities. To date, low levels of FGF have not been correlated with a pathophysiologic state. We report that blood vessels of spontaneously hypertensive rats are shown to be associated with a marked decrement in endothelial basic FGF content. This decrement correlates both with hypertension and with a decrease in the endothelial content of nitric oxide synthase. Restoration of FGF to physiological levels in the vascular wall, either by systemic administration or by in vivo gene transfer, significantly augmented the number of endothelial cells with positive immunostaining for nitric oxide synthase, corrected hypertension, and ameliorated endothelial-dependent responses to vasoconstrictors. These results suggest an important role for FGFs in blood pressure homeostasis and open new avenues for the understanding of the etiology and treatment of hypertension. Images Fig. 2 Fig. 4 PMID:8876251

Cuevas, P; García-Calvo, M; Carceller, F; Reimers, D; Zazo, M; Cuevas, B; Muñoz-Willery, I; Martínez-Coso, V; Lamas, S; Giménez-Gallego, G

1996-01-01

269

Reliability Analysis of a Composite Wind Turbine Blade Section Using the Model Correction Factor Method: Numerical Study and Validation  

NASA Astrophysics Data System (ADS)

Reliability analysis of fiber-reinforced composite structures is a relatively unexplored field, and it is therefore expected that engineers and researchers trying to apply such an approach will meet certain challenges until more knowledge is accumulated. While doing the analyses included in the present paper, the authors have experienced some of the possible pitfalls on the way to complete a precise and robust reliability analysis for layered composites. Results showed that in order to obtain accurate reliability estimates it is necessary to account for the various failure modes described by the composite failure criteria. Each failure mode has been considered in a separate component reliability analysis, followed by a system analysis which gives the total probability of failure of the structure. The Model Correction Factor method used in connection with FORM (First-Order Reliability Method) proved to be a fast and efficient way to calculate the reliability index of a complex composite structure.

Dimitrov, Nikolay; Friis-Hansen, Peter; Berggreen, Christian

2013-02-01

270

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. PMID:23890257

2013-01-01

271

Dynamic correction for parallel conductance, GP, and gain factor, ?, in invasive murine left ventricular volume measurements  

PubMed Central

The conductance catheter technique could be improved by determining instantaneous parallel conductance (GP), which is known to be time varying, and by including a time-varying calibration factor in Baan's equation [?(t)]. We have recently proposed solutions to the problems of both time-varying GP and time-varying ?, 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 GP 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 ?l error) compared with those same parameters calculated by SV calibrated conductance (35.89 ± 73.22 ?l error) and by cuvette calibrated conductance (?7.53 ± 16.23 ?l ES and ?29.10 ± 31.53 ?l ED error). To utilize the admittance approach, myocardial permittivity (?m) and conductivity (?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 ?l, 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/?l Wei's equation (P < 0.05), 3.3 ± 1.2 to 8.8 ± 5.1 mmHg/?l using Baan's equation (P = not significant)]. New theory and method for instantaneous GP 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 GP) and Wei's equation (dynamic ?) 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.; Treviño, Rodolfo J.; Valvano, Jonathan W.; Pearce, John A.

2009-01-01

272

Factors affecting quality of temperature models for the pre-appearance interval of forensically useful insects.  

PubMed

In the case of many forensically important insects an interval preceding appearance of an insect stage on a corpse (called the pre-appearance interval or PAI) is strongly temperature-dependent. Accordingly, it was proposed to estimate PAI from temperature by using temperature models for PAI of particular insect species and temperature data specific for a given case. The quality of temperature models for PAI depends on the protocols for PAI field studies. In this article we analyze effects of sampling frequency and techniques, temperature data, as well as the size of a sample on the quality of PAI models. Models were created by using data from a largely replicated PAI field study, and their performance in estimation was tested with external body of PAI data. It was found that low frequency of insect sampling distinctly deteriorated temperature models for PAI. The effect of sampling techniques was clearly smaller. Temperature data from local weather station gave models of poor quality, however their retrospective correction clearly improved the models. Most importantly, current results demonstrate that sample size in PAI field studies may be substantially reduced, with no model deterioration. Samples consisting of 11-14 carcasses gave models of high quality, as long as the whole range of relevant temperatures was studied. Moreover, it was found that carcasses exposed in forests and carcasses exposed in early spring are particularly important, as they ensure that PAI data is collected at low temperatures. A preliminary best practice model for PAI field studies is given. PMID:25541074

Matuszewski, Szymon; M?dra, Anna

2015-02-01

273

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

274

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

275

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

276

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

277

Perturbation on-time (POT) control and inhibit time control (ITC) in suppression of THD of power factor correction (PFC) design  

Microsoft Academic Search

The PFC control is more popular in today’s green power mainstream for improving power utilization efficiency. The power factor correction shapes the input current of off-line power supplies to increase the real power available from the AC source. The passive PFC technique may need large external inductors and capacitors to achieve PF value only about 75%. Today, electrical equipment in

Jen-Chieh Tsai; Chi-Lin Chen; Yi-Ting Chen; Chia-Lung Ni; Chun-Yen Chen; Ke-Horng Chen; Chih-Jen Chen; Heng-Lin Pan

2011-01-01

278

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

René P. T. Bascopé; Carlos G. C. Branco; Cícero M. T. Cruz; Eduardo F. de Oliveira; Gean J. M. Sousa

2009-01-01

279

Identification of possible factors influencing temperatures elevation during implant site preparation with piezoelectric technique  

PubMed Central

Summary Background Overheating during implant site preparation negatively affects the osseointegration process as well the final outcome of implant rehabilitations. Piezoelectric techniques seem to provide to a gentle implant preparation although few scientific reports have investigated the heat generation and its underlying factors. Purpose To investigate, through a proper methodological approach, the main factors influencing temperature rise during piezoelectric implant site preparation. Materials and methods Different piezoelectric tips (IM1s, IM2, P2-3, IM3, Mectron Medical Technology, Carasco, Italy) have been tested. The experimental set-up consisted in a mechanical positioning device equipped with a load cell and a fluoroptic thermometer. Results The first tip of the sequence (IM1s) generated the highest temperature increasing (?T). The diamond tips (IM1s and P2-3) determined higher ?T values than the smooth tips (IM2 and IM3). Further tests with IM1s suggested that the temperature elevation during the first thirty seconds may be predictive of the maximal temperature as well as of the overall thermal impact. Conclusions Working load, working movements management and bone features resulted to be the main factors influencing temperature rise during piezoelectric implant site preparation. Irrigant temperature and clogging effect may also synergically contribute to the heat generation. PMID:25774245

Lamazza, Luca; Laurito, Domenica; Lollobrigida, Marco; Brugnoletti, Orlando; Garreffa, Girolamo; De Biase, Alberto

2014-01-01

280

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

281

Effects of metal ions and temperature on the interaction of cobra venom factor and human complement factor B  

SciTech Connect

The alternative pathway C3 convertase is formed by the equilibrium association of factor B with cobra venom factor (CVF) followed by an activation step catalyzed by Factor D. However, the association with CVF has only occasionally been demonstrated and has not been quantitatively analyzed. Here they show that in the absence of metals the two proteins have residual affinity and associate in a one-to-one stoichiometry with a dissociation constant of 11.6 ..mu..M. Upon the addition of metal ions the complex is stabilized only 10- to 20-fold in the order Ni/sup 2 +/ (K/sub d/ = 6.62 ..mu..M) < Mg/sup 2 +/ (K/sub d/ = 1.05 ..mu..M) < Mn/sup 2 +/ (K/sub d/ = 0.41 ..mu..M). Hence, even in the presence of metal ions the interaction is weak. They observed no temperature dependence of the dissociation of the proteins in the presence of Mg/sup 2 +/, however in the presence of EDTA or Ni/sup 2 +/ the affinity is increased 3- to 5-fold as the temperature is lowered from 21/sup 0/ to 14/sup 0/C. This association was demonstrated in the analytical ultracentrifuge at sedimentation equilibrium employing a combination of single- and multiple-independent variable nonlinear least squares analytical techniques. Two different numerical approaches gave very similar results.

Spangler, C.J.; O'Keefe, M.C.; Osborne, J.C. Jr.; Hensley, P.; Vogel, C.W.

1986-03-05

282

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...

283

Temperature trumps light: Teasing apart interactive factors controlling non-indigenous Zostera japonica growth  

EPA Science Inventory

In the Pacific Northwest Zostera marina and Z. japonica co-exist by occupying separate elevation niches. We conducted two mesocosm experiments to evaluate light and temperature as factors controlling the disjunct distribution of congeners. The first study tests the hypothesis t...

284

Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana  

Technology Transfer Automated Retrieval System (TEKTRAN)

Despite much effort, a robust protocol for in vitro germination of Arabidopsis thaliana pollen was still elusive. Here we show that controlled temperatures, a largely disregarded factor in previous studies, and a simple optimized medium, solidified or liquid, yielded pollen germination rates above 8...

285

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

286

High Temperature as a Risk Factor for Infectious Diarrhea in Shanghai, China  

PubMed Central

Background Recent studies indicate that ambient temperature could be a risk factor for infectious diarrhea, but evidence for such a relation is limited in China. Methods We investigated the short-term association between daily temperature and physician-diagnosed infectious diarrhea during 2008–2010 in Shanghai, China. We adopted a time-series approach to analyze the data and a quasi-Poisson regression model with a natural spline-smoothing function to adjust for long-term and seasonal trends, as well as other time-varying covariates. Results There was a significant association between temperature and outpatient visits for diarrhea. A 1°C increase in the 6-day moving average of temperature was associated with a 2.68% (95% CI: 1.83%, 3.52%) increase in outpatient visits for diarrhea. We did not find a significant association between rainfall and infectious diarrhea. Conclusions High temperature might be a risk factor for infectious diarrhea in Shanghai. Public health programs should focus on preventing diarrhea related to high temperature among city residents. PMID:23994865

Zhou, Xiaodan; Zhou, Yanbing; Chen, Renjie; Ma, Wenjuan; Deng, Haiju; Kan, Haidong

2013-01-01

287

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 30°C with strains that can cause disease below 20°C 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 18°C 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. PMID:24725348

2014-01-01

288

Experimental determination of the weighting factor for the energy window subtraction–based downscatter correction for I-123 in brain SPECT studies  

PubMed Central

Correction for downscatter in I-123 SPECT can be performed by the subtraction of a secondary energy window from the main window, as in the triple-energy window method. This is potentially noise sensitive. For studies with limited amount of counts (e.g. dynamic studies), a broad subtraction window with identical width is preferred. This secondary window needs to be weighted with a factor higher than one, due to a broad backscatter peak from high-energy photons appearing at 172 keV. Spatial dependency and the numerical value of this weighting factor and the image contrast improvement of this correction were investigated in this study. Energy windows with a width of 32 keV were centered at 159 keV and 200 keV. The weighting factor was measured both with an I-123 point source and in a dopamine transporter brain SPECT study in 10 human subjects (5 healthy subjects and 5 patients) by minimizing the background outside the head. Weighting factors ranged from 1.11 to 1.13 for the point source and from 1.16 to 1.18 for human subjects. Point source measurements revealed no position dependence. After correction, the measured specific binding ratio (image contrast) increased significantly for healthy subjects, typically by more than 20%, while the background counts outside of all subjects were effectively removed. A weighting factor of 1.1–1.2 can be applied in clinical practice. This correction effectively removes downscatter and significantly improves image contrast inside the brain. PMID:21170186

de Nijs, Robin; Holm, Søren; Thomsen, Gerda; Ziebell, Morten; Svarer, Claus

2010-01-01

289

Systematic Error Correction of Dynamical Seasonal Prediction of Sea Surface Temperature Using a Stepwise Pattern Project Method  

E-print Network

with increased scientific and economic interest in seasonal climate prediction and predictabil- ity. Since a Stepwise Pattern Project Method JONG-SEONG KUG Climate Environment System Research Center, Seoul National developed based on the pattern projection method in order to empirically correct the dynamical seasonal

Kang, In-Sik

290

Conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation 1948--1951. Hanford Environmental Dose Reconstruction Project  

SciTech Connect

This report is a part of the Hanford Environmental Dose Reconstruction (HEDR) Project, whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. The key radionuclide emitted that would affect the radiation dose was iodine-131 (Napier 1992). Because the early methods of measuring iodine-131 were not comparable to later techniques, conversion and correction factors are needed to convert the historical measurement data into concentration values that would be determined using today`s knowledge and technologies. This report describes the conversion and correction factors developed for reconstructing historical measurements of iodine-131 in Hanford-area vegetation, which was collected from 1948 through the end of December 1951.

Denham, D.H.; Mart, E.I.; Thiede, M.E.

1993-09-01

291

NOTE: Determination of the recombination correction factor kS for some specific plane-parallel and cylindrical ionization chambers in pulsed photon and electron beams  

Microsoft Academic Search

It has been shown from an evaluation of the inverse reading of the dosemeter (1\\/M) against the inverse of the polarizing voltage (1\\/V), obtained with a number of commercially available ionization chambers, using dose per pulse values between 0.16 and 5 mGy, that a linear relationship between the recombination correction factor kS and dose per pulse (DPP) can be found.

G. Bruggmoser; R. Saum; A. Schmachtenberg; F. Schmid; E. Schüle

2007-01-01

292

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

PubMed

EGSnrc calculations of ion chamber response and Spencer-Attix (SA) restricted stopping-power ratios are used to test the assumptions of the SA cavity theory and to assess the accuracy of this theory as it applies to the air kerma formalism for 60Co beams. Consistent with previous reports, the EGSnrc calculations show that the SA cavity theory, as it is normally applied, requires a correction for the perturbation of the charged particle fluence (K(fl)) by the presence of the cavity. The need for K(fl) corrections arises from the fact that the standard prescription for choosing the low-energy threshold delta in the SA restricted stopping-power ratio consistently underestimates the values of delta needed if no perturbation to the fluence is assumed. The use of fluence corrections can be avoided by appropriately choosing delta, but it is not clear how delta can be calculated from first principles. Values of delta required to avoid K(fl) corrections were found to be consistently higher than delta values obtained using the conventional approach and are also observed to be dependent on the composition of the wall in addition to the cavity size. Values of K(fl) have been calculated for many of the graphite-walled ion chambers used by the national metrology institutes around the world and found to be within 0.04% of unity in all cases, with an uncertainty of about 0.02%. PMID:19810491

La Russa, D J; Rogers, D W O

2009-09-01

293

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

SciTech Connect

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

La Russa, D. J.; Rogers, D. W. O. [Ottawa Carleton Institute of Physics, Carleton University Campus, Ottawa, Ontario K1S 5B6 (Canada)

2009-09-15

294

Factors Influencing the Completion of the GED in a Federal Correctional Setting a Multiple Regression Correlation-Predictive Study  

ERIC Educational Resources Information Center

Correctional education's primary goal is to reduce recidivism and increase employment among ex-offenders. The Bureau of Prison's practical goal in its mandatory GED program is to maximize the number of inmates obtaining the GED in a given time period. The purpose of this research is to model the number of instructional hours an inmate…

Akers, Kimberly

2013-01-01

295

Volume and loss optimization of high frequency transformer for compact switch mode power supply considering corrected waveform factor  

Microsoft Academic Search

A new procedure for optimum design of high frequency transformers is presented. The presented design method is based on a restatement and correction of the traditional transformer design equations to include non-sinusoidal switching waveforms and high frequency skin and proximity effects. In this optimization procedure both electric and thermal effects in the transformer is considered. Wave form of voltage and

H. R. Karampoorian; Gh. Papi; A. Zadehgol

2006-01-01

296

Uptake of inorganic phosphate is a limiting factor for Saccharomyces cerevisiae during growth at low temperatures.  

PubMed

The fermenting ability of Saccharomyces at low temperatures is crucial for the development of alcoholic beverages, but the key factors for the cold tolerance of yeast are not well known. In this report, we present the results of a screening for genes able to confer cold tolerance by overexpression in a laboratory yeast strain auxotrophic for tryptophan. We identified genes of tryptophan permeases (TAT1 and TAT2), suggesting that the first limiting factor in the growth of tryptophan auxotrophic yeast at low temperatures is tryptophan uptake. This fact is of little relevance to industrial strains which are prototrophic for tryptophan. Then, we screened for genes able to confer growth at low temperatures in tryptophan-rich media and found several genes related to phosphate uptake (PHO84, PHO87, PHO90 and GTR1). This suggests that without tryptophan limitation, uptake of inorganic phosphate becomes the limiting factor. We have found that overexpression of the previously uncharacterized ORF YCR015c/CTO1 increases the uptake of inorganic phosphate. Also, genes involved in ergosterol biosynthesis (NSG2) cause improvement of growth at 10°C, dependent on tryptophan uptake, while the gluconeogenesis gene PCK1 and the proline biosynthesis gene PRO2 cause an improvement in growth at 10°C, independent of tryptophan and phosphate uptake. PMID:25725023

Vicent, Isabel; Navarro, Alfonso; Mulet, Jose M; Sharma, Sukesh; Serrano, Ramón

2015-05-01

297

A robust approach to correct for pronounced errors in temperature measurements by controlling radiation damping feedback fields in solution NMR  

NASA Astrophysics Data System (ADS)

Accurate temperature measurement is a requisite for obtaining reliable thermodynamic and kinetic information in all NMR experiments. A widely used method to calibrate sample temperature depends on a secondary standard with temperature-dependent chemical shifts to report the true sample temperature, such as the hydroxyl proton in neat methanol or neat ethylene glycol. The temperature-dependent chemical shift of the hydroxyl protons arises from the sensitivity of the hydrogen-bond network to small changes in temperature. The frequency separation between the alkyl and the hydroxyl protons are then converted to sample temperature. Temperature measurements by this method, however, have been reported to be inconsistent and incorrect in modern NMR, particularly for spectrometers equipped with cryogenically-cooled probes. Such errors make it difficult or even impossible to study chemical exchange and molecular dynamics or to compare data acquired on different instruments, as is frequently done in biomolecular NMR. In this work, we identify the physical origins for such errors to be unequal amount of dynamical frequency shifts on the alkyl and the hydroxyl protons induced by strong radiation damping (RD) feedback fields. Common methods used to circumvent RD may not suppress such errors. A simple, easy-to-implement solution was demonstrated that neutralizes the RD effect on the frequency separation by a "selective crushing recovery" pulse sequence to equalize the transverse magnetization of both spin species. Experiments using cryoprobes at 500 MHz and 800 MHz demonstrated that this approach can effectively reduce the errors in temperature measurements from about ±4.0 K to within ±0.4 K in general.

Wolahan, Stephanie M.; Li, Zhao; Hsu, Chao-Hsiung; Huang, Shing-Jong; Clubb, Robert; Hwang, Lian-Pin; Lin, Yung-Ya

2014-11-01

298

A robust approach to correct for pronounced errors in temperature measurements by controlling radiation damping feedback fields in solution NMR.  

PubMed

Accurate temperature measurement is a requisite for obtaining reliable thermodynamic and kinetic information in all NMR experiments. A widely used method to calibrate sample temperature depends on a secondary standard with temperature-dependent chemical shifts to report the true sample temperature, such as the hydroxyl proton in neat methanol or neat ethylene glycol. The temperature-dependent chemical shift of the hydroxyl protons arises from the sensitivity of the hydrogen-bond network to small changes in temperature. The frequency separation between the alkyl and the hydroxyl protons are then converted to sample temperature. Temperature measurements by this method, however, have been reported to be inconsistent and incorrect in modern NMR, particularly for spectrometers equipped with cryogenically-cooled probes. Such errors make it difficult or even impossible to study chemical exchange and molecular dynamics or to compare data acquired on different instruments, as is frequently done in biomolecular NMR. In this work, we identify the physical origins for such errors to be unequal amount of dynamical frequency shifts on the alkyl and the hydroxyl protons induced by strong radiation damping (RD) feedback fields. Common methods used to circumvent RD may not suppress such errors. A simple, easy-to-implement solution was demonstrated that neutralizes the RD effect on the frequency separation by a "selective crushing recovery" pulse sequence to equalize the transverse magnetization of both spin species. Experiments using cryoprobes at 500 MHz and 800 MHz demonstrated that this approach can effectively reduce the errors in temperature measurements from about ±4.0 K to within ±0.4 K in general. PMID:25299766

Wolahan, Stephanie M; Li, Zhao; Hsu, Chao-Hsiung; Huang, Shing-Jong; Clubb, Robert; Hwang, Lian-Pin; Lin, Yung-Ya

2014-11-01

299

Correcting artifacts in transition to a wound optic fiber: Example from high-resolution temperature profiling in the Dead Sea  

NASA Astrophysics Data System (ADS)

Spatial resolution fiber-optic cables allow for detailed observation of thermally complex heterogeneous hydrologic systems. A commercially produced high spatial resolution helically wound optic fiber sensing cable is employed in the Dead Sea, in order to study the dynamics of thermal stratification of the hypersaline lake. Structured spatial artifacts were found in the data from the first 10 m of cable (110 m of fiber length) following the transition from straight fiber optic. The Stokes and Anti-Stokes signals indicate that this is the result of differential attenuation, thought to be due to cladding losses. Though the overall spatial form of the loss was consistent, the fine structure of the loss changed significantly in time, and was strongly asymmetrical, and thus was not amenable to standard calibration methods. Employing the fact that the cable was built with a duplex construction, and using high-precision sensors mounted along the cable, it was possible to correct the artifact in space and time, while retaining the high-quality of data obtained in the early part of the cable (prior to significant optical attenuation). The defect could easily be overlooked; however, reanalyzing earlier experiments, we have observed the same issue with installations employing similar cables in Oregon and France, so with this note we both alert the community to this persistent concern and provide an approach to correct the data in case of similar problems.

Arnon, Ali; Selker, John; Lensky, Nadav

2014-06-01

300

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

301

Factors influencing the acquisition and correct and consistent use of the top-lit updraft cookstove in Uganda.  

PubMed

This study looked at the effects of select behavior change interventions on the purchase and the correct and consistent use of a locally fabricated top-lit updraft (TLUD) stove in Uganda. Behavior change interventions included training of community sales agents and village health team volunteers on household air pollution and correct use, referral of interested community members to sales agents, community cooking demonstrations, information flyers, and direct sales of TLUDs and processed wood. Qualitative and quantitative research methods shaped interventions and were used to understand attitudes and practices related to TLUD stove acquisition and use. Results showed that TLUDs were appreciated because they use wood efficiently, cook quickly, reduce smoke, and produce charcoal. However, the substantial purchase price barrier, combined with the cost of processed wood, effectively eliminated the cost savings from its significant fuel efficiency. This made it difficult for the TLUD to be a meaningful part of most households' cooking practices. PMID:25839205

Namagembe, Allen; Muller, Nancy; Scott, Lisa Mueller; Zwisler, Greg; Johnson, Michael; Arney, Jennifer; Charron, Dana; Mugisha, Emmanuel

2015-03-31

302

Defective functional activity and accelerated apoptosis in neutrophils from children with cancer are differentially corrected by granulocyte and granulocyte-macrophage colony stimulating factors in vitro.  

PubMed

We have previously shown that polymorphonuclear leucocytes (PMN) harvested from children with cancer and exposed to chemotherapy exhibit defective bactericidal activities against both Gram-positive and Gram-negative microorganisms as well as accelerated apoptosis. In this study, PMN from children with cancer were evaluated to compare in vitro the corrective effects of the two myeloid colony stimulating factors G-CSF and GM-CSF on these defective pathways. Both G-CSF and GM-CSF were able to increase the defective bactericidal activities against S. aureus and E. coli. However, GM-CSF was consistently superior to G-CSF in correcting PMN microbicidal activity; this correction was incomplete since it did not reach the level observed in normal PMN exposed to GM-CSF. The accelerated apoptosis of PMN was not affected by G-CSF. In contrast, GM-CSF significantly prolonged the survival of the PMN although it did not reach the level of survival observed with normal PMN exposed to GM-CSF. These observations were consistent with other studies indicating that in PMN, microbicidal activities and apoptosis are differentially sensitive to the myeloid growth factors G-CSF and GM-CSF. PMID:10468870

Lejeune, M; Cantinieaux, B; Harag, S; Ferster, A; Devalck, C; Sariban, E

1999-09-01

303

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

304

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 25°C (room temperature) and 4°C (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 4°C and 25°C; and APTT for ?12?h at 4°C and ?8?h at 25°C. PMID:24463857

Feng, Limin; Zhao, Ying; Zhao, Hongcan; Shao, Zhexin

2014-01-01

305

Do current models correctly predict the L-band terrestrial brightness temperature when crops begin to senesce?  

Technology Transfer Automated Retrieval System (TEKTRAN)

The microwave terrestrial brightness temperature is sensitive to soil moisture, the water content of the first few centimeters of Earth's surface. The European Space Agency will soon launch the Soil Moisture and Ocean Salinity (SMOS) mission, the world's first soil moisture satellite that will measu...

306

Effect of temperature on growth of Vibrio parahaemolyticus [corrected] and Vibrio vulnificus in flounder, salmon sashimi and oyster meat.  

PubMed

Vibrio parahaemolyticus and Vibrio vulnificus are the major pathogenic Vibrio species which contaminate ready-to-eat seafood. The purpose of this study was to evaluate the risk of human illness resulting from consumption of ready-to-eat seafood such as sashimi and raw oyster meat due to the presence of V. parahaemolyticus and V. vulnificus. We compared the growth kinetics of V. parahaemolyticus and V. vulnificus strains in broth and ready-to-eat seafood, including flounder and salmon sashimi, as a function of temperature. The growth kinetics of naturally occurring V. vulnificus in raw oyster meat was also evaluated. The minimum growth temperatures of V. parahaemolyticus and V. vulnificus in broth were 13 °C and 11 °C, respectively. Overall, significant differences in lag time (LT) and specific growth rate (SGR) values between flounder and salmon sashimi were observed at temperatures ranging from 13 °C to 30 °C (p < 0.05). The growth of naturally occurring V. vulnificus reached stationary phase at ~4 log CFU/g in oysters, regardless of the storage temperature. This data indicates that the population of V. vulnificus in oysters did not reach the maximum population density as observed in the broth, where growth of V. vulnificus and V. parahaemolyticus isolated from oysters grew up to >8 log CFU/mL. PMID:23330227

Kim, Yoo Won; Lee, Soon Ho; Hwang, In Gun; Yoon, Ki Sun

2012-12-01

307

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

308

Quantum corrections to the ground state energy of inhomogeneous neutron matter  

E-print Network

We estimate the quantum corrections to the ground state energy in neutron matter (which could be termed as well either shell correction energy or Casimir energy) at subnuclear densities, where various types of inhomogeneities (bubbles, rods, plates) are energetically favorable. We show that the magnitude of these energy corrections are comparable to the energy differences between various types of inhomogeneous phases. We discuss the dependence of these corrections on a number of physical parameters (density, filling factor, temperature, lattice distortions).

Aurel Bulgac; Piotr Magierski

2002-02-12

309

NOTE: Determination of the recombination correction factor kS for some specific plane-parallel and cylindrical ionization chambers in pulsed photon and electron beams  

NASA Astrophysics Data System (ADS)

It has been shown from an evaluation of the inverse reading of the dosemeter (1/M) against the inverse of the polarizing voltage (1/V), obtained with a number of commercially available ionization chambers, using dose per pulse values between 0.16 and 5 mGy, that a linear relationship between the recombination correction factor kS and dose per pulse (DPP) can be found. At dose per pulse values above 1 mGy the method of a general equation with coefficients dependent on the chamber type gives more accurate results than the Boag method. This method was already proposed by Burns and McEwen (1998, Phys. Med. Biol. 43 2033) and avoids comprehensive and time-consuming measurements of Jaffé plots which are a prerequisite for the application of the multi-voltage analysis (MVA) or the two-voltage analysis (TVA). We evaluated and verified the response of ionization chambers on the recombination effect in pulsed accelerator beams for both photons and electrons. Our main conclusions are: (1) The correction factor kS depends only on the DPP and the chamber type. There is no influence of radiation type and energy. (2) For all the chambers investigated there is a linear relationship between kS and DPP up to 5 mGy/pulse, and for two chambers we could show linearity up to 40 mGy/pulse. (3) A general formalism, such as that of Boag, characterizes chambers exclusively by the distance of the electrodes and gives a trend for the correction factor, and therefore (4) a general formalism has to reflect the influence of the chamber construction on the recombination by the introduction of chamber-type dependent coefficients.

Bruggmoser, G.; Saum, R.; Schmachtenberg, A.; Schmid, F.; Schüle, E.

2007-01-01

310

Correction of the characteristics of strongly irradiated SiC-based nuclear radiation detectors by increasing the working temperature  

Microsoft Academic Search

Owing to the wide bandgap of silicon carbide, p-n structures based on this semiconductor are characterized by low densities of the generation current. For this reason, it\\u000a is possible to increase the working temperature of SiC-based p-n detectors of nuclear radiation so as to control the time of emission of nonequilibrium carriers from defect-related trapping\\u000a centers. We have studied strongly

A. M. Ivanov; N. B. Strokan; A. A. Lebedev

2009-01-01

311

Correction of the characteristics of strongly irradiated SiC-based nuclear radiation detectors by increasing the working temperature  

Microsoft Academic Search

Owing to the wide bandgap of silicon carbide, p- n structures based on this semiconductor are characterized by low densities of the generation current. For this reason, it is possible to increase the working temperature of SiC-based p- n detectors of nuclear radiation so as to control the time of emission of nonequilibrium carriers from defect-related trapping centers. We have

A. M. Ivanov; N. B. Strokan; A. A. Lebedev

2009-01-01

312

High Thermoelectric Power Factor Near Room Temperature in Full-Heusler Alloys  

NASA Astrophysics Data System (ADS)

We present results on the electrical resistivity, Seebeck coefficient, and thermal conductivity for the Heusler alloys Fe2VAl1- x Si x and Fe2VAl1- x Sn x synthesized using standard arc-melting techniques. While alloys with x = 0 are p-type, upon substitution of Si or Sn for Al the alloys can be made n-type with optimized sample compositions exhibiting thermoelectric power factors in excess of that of bismuth telluride near room temperature. The lattice thermal conductivity ? L of these alloys is too large to produce a high figure of merit; the prospects for and initial attempts at lowering ? L are discussed.

Skoug, Eric J.; Zhou, Chen; Pei, Yanzhong; Morelli, Donald T.

2009-07-01

313

Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature  

NASA Astrophysics Data System (ADS)

We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×1016 Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Galliou, S.; Bourquin, R.; Tobar, M. E.

2014-12-01

314

Conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation, 1945--1947. Hanford Environmental Dose Reconstruction Project  

SciTech Connect

This report is a result of the Hanford Environmental Dose Reconstruction (HEDR) Project whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the U.S. Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is conducted by Battelle, Pacific Northwest Laboratories (BNW). One of the radionuclides emitted that would affect the radiation dose was iodine-131. This report describes in detail the reconstructed conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation which was collected from the beginning of October 1945 through the end of December 1947.

Mart, E.I.; Denham, D.H.; Thiede, M.E.

1993-12-01

315

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. PMID:25050049

Pham, C. H.; Vu, C. C.; Sommer, S. G.; Bruun, S.

2014-01-01

316

ECOC comparison exercise with identical thermal protocols after temperature offset correction - instrument diagnostics by in-depth evaluation of operational parameters  

NASA Astrophysics Data System (ADS)

A comparison exercise on thermal-optical elemental carbon/organic carbon (ECOC) analysers was carried out among 17 European laboratories. Contrary to previous comparison exercises, the 17 participants made use of an identical instrument set-up, after correcting for temperature offsets with the application of a recently developed temperature calibration kit (Sunset Laboratory Inc, OR, US). Temperature offsets reported by participants ranged from -93 to +100 °C per temperature step. Five filter samples and two sucrose solutions were analysed with both the EUSAAR2 and NIOSH870 thermal protocols. z scores were calculated for total carbon (TC); nine outliers and three stragglers were identified. Three outliers and eight stragglers were found for EC. Overall, the participants provided results between the warning levels with the exception of two laboratories that showed poor performance, the causes of which were identified and corrected through the course of the comparison exercise. The TC repeatability and reproducibility (expressed as relative standard deviations) were 11 and 15% for EUSAAR2 and 9.2 and 12% for NIOSH870; the standard deviations for EC were 15 and 20% for EUSAAR2 and 20 and 26% for NIOSH870. TC was in good agreement between the two protocols, TCNIOSH870 = 0.98 × TCEUSAAR2 (R2 = 1.00, robust means). Transmittance (TOT) calculated EC for NIOSH870 was found to be 20% lower than for EUSAAR2, ECNIOSH870 = 0.80 × ECEUSAAR2 (R2 = 0.96, robust means). The thermograms and laser signal values were compared and similar peak patterns were observed per sample and protocol for most participants. Notable deviations from the typical patterns indicated either the absence or inaccurate application of the temperature calibration procedure and/or pre-oxidation during the inert phase of the analysis. Low or zero pyrolytic organic carbon (POC), as reported by a few participants, is suggested as an indicator of an instrument-specific pre-oxidation. A sample-specific pre-oxidation effect was observed for filter G, for all participants and both thermal protocols, indicating the presence of oxygen donors on the suspended particulate matter. POC (TOT) levels were lower for NIOSH870 than for EUSAAR2, which is related to the heating profile differences of the two thermal protocols.

Panteliadis, P.; Hafkenscheid, T.; Cary, B.; Diapouli, E.; Fischer, A.; Favez, O.; Quincey, P.; Viana, M.; Hitzenberger, R.; Vecchi, R.; Saraga, D.; Sciare, J.; Jaffrezo, J. L.; John, A.; Schwarz, J.; Giannoni, M.; Novak, J.; Karanasiou, A.; Fermo, P.; Maenhaut, W.

2015-02-01

317

Correction factors for the ISO rod phantom, a cylinder phantom, and the ICRU sphere for reference beta radiation fields of the BSS 2  

NASA Astrophysics Data System (ADS)

The International Organization for Standardization (ISO) requires in its standard ISO 6980 that beta reference radiation fields for radiation protection be calibrated in terms of absorbed dose to tissue at a depth of 0.07 mm in a slab phantom (30 cm x 30 cm x 15 cm). However, many beta dosemeters are ring dosemeters and are, therefore, irradiated on a rod phantom (1.9 cm in diameter and 30 cm long), or they are eye dosemeters possibly irradiated on a cylinder phantom (20 cm in diameter and 20 cm high), or area dosemeters irradiated free in air with the conventional quantity value (true value) being defined in a sphere (30 cm in diameter, made of ICRU tissue (International Commission on Radiation Units and Measurements)). Therefore, the correction factors for the conventional quantity value in the rod, the cylinder, and the sphere instead of the slab (all made of ICRU tissue) were calculated for the radiation fields of 147Pm, 85Kr, 90Sr/90Y, and, 106Ru/106Rh sources of the beta secondary standard BSS 2 developed at PTB. All correction factors were calculated for 0° up to 75° (in steps of 15°) radiation incidence. The results are ready for implementation in ISO 6980-3 and have recently been (partly) implemented in the software of the BSS 2.

Behrens, R.

2015-03-01

318

Correction of systematic model forcing bias of CLM using assimilation of cosmic-ray neutrons and land surface temperature: a study in the Heihe catchment, China  

NASA Astrophysics Data System (ADS)

The recent development of the non-invasive cosmic-ray soil moisture sensing technique fills the gap between point scale soil moisture measurements and regional scale soil moisture measurements by remote sensing. A cosmic-ray probe measures soil moisture for a footprint with a diameter of ~600 m (at sea level) and with an effective measurement depth between 12 and 76 cm, depending on the soil humidity. In this study, it was tested whether neutron counts also allow to correct for a systematic error in the model forcings. Lack of water management data often cause systematic input errors to land surface models. Here, the assimilation procedure was tested for an irrigated corn field (Heihe Watershed Allied Telemetry Experimental Research - HiWATER, 2012) where no irrigation data were available as model input although the area a significant amount of water was irrigated. Measured cosmic-ray neutron counts and Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) products were jointly assimilated into the Community Land Model (CLM) with the Local Ensemble Transform Kalman Filter. Different data assimilation scenarios were evaluated, with assimilation of LST and/or cosmic-ray neutron counts, and possibly parameter estimation of leaf area index (LAI). The results show that the direct assimilation of cosmic-ray neutron counts can improve the soil moisture and evapotranspiration (ET) estimation significantly, correcting for lack of information on irrigation amounts. The joint assimilation of neutron counts and LST could improve further the ET estimation, but the information content of neutron counts exceeded the one of LST. Additional improvement was achieved by calibrating LAI, which after calibration was also closer to independent field measurements. It was concluded that assimilation of neutron counts was useful for ET and soil moisture estimation even if the model has a systematic bias like neglecting irrigation. However, also the assimilation of LST helped to correct the systematic model bias introduced by neglecting irrigation and LST could be used to update soil moisture with state augmentation.

Han, X.; Hendricks Franssen, H.-J.; Rosolem, R.; Jin, R.; Li, X.; Vereecken, H.

2014-07-01

319

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

320

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

321

Perturbation correction factors for the NACP-02 plane-parallel ionization chamber in water in high-energy electron beams  

NASA Astrophysics Data System (ADS)

Recent dosimetry protocols for clinical high-energy electron beams recommend measurements of absorbed dose-to-water with a plane-parallel or cylindrical ionization chamber. For well-guarded plane-parallel ionization chambers, the ionization chamber perturbation factor in water, pQ, has a recommended value of unity in all protocols. This assumption was investigated in detail in this study for one of the recommended ionization chambers in the protocols: the Scanditronix NACP-02 plane-parallel ionization chamber. Monte Carlo (MC) simulations of the NACP-02 ionization chamber with the EGSnrc code were validated against backscatter experiments. MC simulations were then used to calculate pwall, pcav and pQ perturbation factors and water-to-air Spencer-Attix stopping powers in 4-19 MeV electron beams of a calibration laboratory (NPL), and in 6-22 MeV clinical electron beams from a Varian CL2300 accelerator. Differences between calculated and the currently recommended (Burns et al 1996 Med. Phys. 23 383-8) stopping powers, water-to-air, were found to be limited to 0.9% at depths between the reference depth zref and the depth where the dose has decreased to 50% of the maximum dose, R50. pwall was found to exceed unity by 2.3% in the 4 MeV NPL calibration beam at zref. For higher energy electron beams pwall decreased to a value of about 1%. Combined with a pcav about 1% below unity for all energies at zref, this was found to cause pQ to exceed unity significantly for all energies. In clinical electron beams all three perturbation factors were found to increase with depth. Our findings indicate that the perturbation factors have to be taken into account in calibration procedures and for clinical depth dose measurements with the NACP-02 ionization chamber.

Verhaegen, F.; Zakikhani, R.; Du Sautoy, A.; Palmans, H.; Bostock, G.; Shipley, D.; Seuntjens, J.

2006-03-01

322

EMRI corrections to the angular velocity and redshift factor of a mass in circular orbit about a Kerr black hole  

E-print Network

This is the first of two papers on computing the self-force in a radiation gauge for a particle moving in circular, equatorial orbit about a Kerr black hole. In the EMRI (extreme-mass-ratio inspiral) framework, with mode-sum renormalization, we compute the renormalized value of the quantity $h_{\\alpha\\beta}u^\\alpha u^\\beta$, gauge-invariant under gauge transformations generated by a helically symmetric gauge vector; and we find the related order $\\frak{m}$ correction to the particle's angular velocity at fixed renormalized redshift (and to its redshift at fixed angular velocity). The radiative part of the perturbed metric is constructed from the Hertz potential which is extracted from the Weyl scalar by an algebraic inversion\\cite{sf2}. We then write the spin-weighted spheroidal harmonics as a sum over spin-weighted spherical harmonics and use mode-sum renormalization to find the renormalization coefficients by matching a series in $L=\\ell+1/2$ to the large-$L$ behavior of the expression for $H := \\frac12 h_{\\alpha\\beta}u^\\alpha u^\\beta $. The non-radiative parts of the perturbed metric associated with changes in mass and angular momentum are calculated in the Kerr gauge.

Abhay G. Shah; John L. Friedman; Tobias S. Keidl

2012-09-26

323

Effect of Temperature on Stability and Activity of Elongation Factor 2 Proteins from Antarctic and Thermophilic Methanogens  

Microsoft Academic Search

Despite the presence and abundance of archaea in low-temperature environments, little information is available regarding their physiological and biochemical properties. In order to investigate the adaptation of archaeal proteins to low temperatures, we purified and characterized the elongation factor 2 (EF-2) protein from the Antarctic methanogen Methanococcoides burtonii, which was expressed in Escherichia coli, and com- pared it to the

TORSTEN THOMAS; RICARDO CAVICCHIOLI

2000-01-01

324

Stress intensity factors for glass-fiber reinforced plastics with an infinite row of parallel cracks at low temperatures  

Microsoft Academic Search

Stress intensity factors are determined for glass-fiber reinforced plastics with an infinite row of parallel cracks at low temperatures under tension. A state of generalized plane strain is assumed. The thermal and mechanical properties as functions of temperature are obtained from the experimental data. Fourier transforms are used to reduce the problem to the solution of a pair of dual

K. Sanada; Y. Shindo; S. Ueda

1998-01-01

325

High Q-factor sapphire whispering gallery mode microwave resonator at single photon energies and millikelvin temperatures  

E-print Network

High Q-factor sapphire whispering gallery mode microwave resonator at single photon energies and millikelvin temperatures Daniel L. Creedon,1,a Yarema Reshitnyk,2 Warrick Farr,1 John M. Martinis,3 Timothy L measured at very low excitation strength E/ 1 and low temperatures T 30 mK . The measurements were

Martinis, John M.

326

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

327

Small fields output factors measurements and correction factors determination for several detectors for a CyberKnife{sup Registered-Sign} and linear accelerators equipped with microMLC and circular cones  

SciTech Connect

Purpose: The use of small photon fields is now an established practice in stereotactic radiosurgery and radiotherapy. However, due to a lack of lateral electron equilibrium and high dose gradients, it is difficult to accurately measure the dosimetric quantities required for the commissioning of such systems. Moreover, there is still no metrological dosimetric reference for this kind of beam today. In this context, the first objective of this work was to determine and to compare small fields output factors (OF) measured with different types of active detectors and passive dosimeters for three types of facilities: a CyberKnife{sup Registered-Sign} system, a dedicated medical linear accelerator (Novalis) equipped with m3 microMLC and circular cones, and an adaptive medical linear accelerator (Clinac 2100) equipped with an additional m3 microMLC. The second one was to determine the k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factors introduced in a recently proposed small field dosimetry formalism for different active detectors.Methods: Small field sizes were defined either by microMLC down to 6 Multiplication-Sign 6 mm{sup 2} or by circular cones down to 4 mm in diameter. OF measurements were performed with several commercially available active detectors dedicated to measurements in small fields (high resolution diodes: IBA SFD, Sun Nuclear EDGE, PTW 60016, PTW 60017; ionizing chambers: PTW 31014 PinPoint chamber, PTW 31018 microLion liquid chamber, and PTW 60003 natural diamond). Two types of passive dosimeters were used: LiF microcubes and EBT2 radiochromic films.Results: Significant differences between the results obtained by several dosimetric systems were observed, particularly for the smallest field size for which the difference in the measured OF reaches more than 20%. For passive dosimeters, an excellent agreement was observed (better than 2%) between EBT2 and LiF microcubes for all OF measurements. Moreover, it has been shown that these passive dosimeters do not require correction factors and can then be used as reference dosimeters. Correction factors for the active detectors have then been determined from the mean experimental OF measured by the passive dosimeters.Conclusions: Four sets of correction factors needed to apply the new small field dosimetry formalism are provided for several active detectors. A protocol for small photon beams OF determination based on passive dosimeters measurements has been recently proposed to French radiotherapy treatment centers.

Bassinet, C.; Huet, C.; Derreumaux, S.; Baumann, M.; Trompier, F.; Roch, P.; Clairand, I. [Institut de Radioprotection et de Surete Nucleaire (IRSN), BP17, 92262 Fontenay-aux-Roses Cedex (France); Brunet, G.; Gaudaire-Josset, S. [Institut de Cancerologie de l'Ouest Rene Gauducheau, bd Jacques Monod, 44805 Saint Herblain Cedex (France); Chea, M.; Boisserie, G. [Groupe Hospitalier Pitie-Salpetriere, 47/83 bd de l'Hopital, 75651 Paris Cedex 13 (France); Lacornerie, T. [Centre Oscar Lambret, 3, rue Frederic Combemale, BP 307, 59020 Lille Cedex (France)

2013-07-15

328

Environmental factors affecting the low temperature isomerization of homohopanes in acidic peat deposits, central China  

NASA Astrophysics Data System (ADS)

Progressively more evidence reveals the abundant occurrence of the C31 homohopane with a 17?, 21?-configuration (C31 ??) in immature peats. This compound is commonly considered to be an indicator of thermal maturity in petroleum source rocks, but in peats it has also been interpreted to reflect the oxidation and subsequent decarboxylation reactions of bacteriohopanepolyols with microbially mediated epimerization at C-17 that is catalyzed by the acidic peat conditions. To learn more about the environmental factors that affect the low-temperature isomerization of homohopanes, we investigated the distribution patterns of homohopanes in a well-studied peat core from the Dajiuhu peatland, central China, together with data from modern surface peat samples from Dajiuhu and three other locations. From comparison with paleotemperature and paleohydrologic records in the peat core, we hypothesize that the ratio of C31 ?? hopane relative to the ?? isomer (C31 ??/??) is mainly influenced on a centennial to millennial timescale by ambient temperature with a secondary effect from redox conditions that are defined by peatland water levels. The surface peat samples revealed that relatively high C31 ??/?? values occurred under pH < 6. These results suggest that pH is indeed an important factor in the low-temperature isomerization of C31 homohopanes, although the magnitude of the pH effect may be less than those of ambient temperature and redox conditions. In both surface peat and peat horizons from the Dajiuhu peatland, the amount of the C31 ?? compound with R configuration relative to that with S configuration (C31 R/S) varied closely with C31 ??/??, suggesting that the epimerization at both C-17 and C-22 may happen synchronously and at similar rates. This study reveals that the isomerization of homohopanes has the potential to reflect paleoenvironmental changes in acidic peat deposits. In addition, acidic peat samples investigated in this and previous studies commonly have relatively high values of C31 ??/?? and C31 R/S, highlighting the potential of homohopane isomers to be tracers of the delivery and deposition of organic matter from acidic settings.

Huang, Xianyu; Meyers, Philip A.; Xue, Jiantao; Gong, Linfeng; Wang, Xinxin; Xie, Shucheng

2015-04-01

329

Perturbation correction factors for the NACP-02 plane-parallel ionization chamber in water in high-energy electron beams.  

PubMed

Recent dosimetry protocols for clinical high-energy electron beams recommend measurements of absorbed dose-to-water with a plane-parallel or cylindrical ionization chamber. For well-guarded plane-parallel ionization chambers, the ionization chamber perturbation factor in water, p(Q), has a recommended value of unity in all protocols. This assumption was investigated in detail in this study for one of the recommended ionization chambers in the protocols: the Scanditronix NACP-02 plane-parallel ionization chamber. Monte Carlo (MC) simulations of the NACP-02 ionization chamber with the EGSnrc code were validated against backscatter experiments. MC simulations were then used to calculate p(wall), p(cav) and p(Q) perturbation factors and water-to-air Spencer-Attix stopping powers in 4-19 MeV electron beams of a calibration laboratory (NPL), and in 6-22 MeV clinical electron beams from a Varian CL2300 accelerator. Differences between calculated and the currently recommended (Burns et al 1996 Med. Phys. 23 383-8) stopping powers, water-to-air, were found to be limited to 0.9% at depths between the reference depth z(ref) and the depth where the dose has decreased to 50% of the maximum dose, R50. p(wall) was found to exceed unity by 2.3% in the 4 MeV NPL calibration beam at z(ref). For higher energy electron beams p(wall) decreased to a value of about 1%. Combined with a p(cav) about 1% below unity for all energies at z(ref), this was found to cause p(Q) to exceed unity significantly for all energies. In clinical electron beams all three perturbation factors were found to increase with depth. Our findings indicate that the perturbation factors have to be taken into account in calibration procedures and for clinical depth dose measurements with the NACP-02 ionization chamber. PMID:16481689

Verhaegen, F; Zakikhani, R; Dusautoy, A; Palmans, H; Bostock, G; Shipley, D; Seuntjens, J

2006-03-01

330

Activity-based anorexia: ambient temperature has been a neglected factor.  

PubMed

Activity-based anorexia refers to the self-starvation of rats exposed to experimental conditions that combine restricted access to food with access to an activity wheel. This paper compares previous studies of this phenomenon in relation to the ambient temperatures (AT) that were employed. On this basis, and from some more direct evidence, we argue that AT is an important, but neglected, factor in activity-based anorexia research. More attention to AT is needed in future research, since its neglect threatens the validity of conclusions drawn from those studies. Furthermore, direct examination of the effect of AT on activity-based anorexia will allow a better understanding of the mechanisms underlying this phenomenon and the possible clinical implications for the treatment of human anorexia nervosa. PMID:12120785

Gutiérrez, Emilio; Vázquez, Reyes; Boakes, R A

2002-06-01

331

Shorter telomere length - A potential susceptibility factor for HIV-associated neurocognitive impairments in South African women [corrected].  

PubMed

The neuropathogenesis of the human immunodeficiency virus (HIV) may manifest as various neurocognitive impairments (NCI). HIV-positive individuals also have significantly shorter telomere length (TL) in peripheral blood mononuclear cells (PBMCs) and CD8+ T cells compared to HIV-negative individuals. Additionally, reduced TL has been found to be associated with chronic psychological stress. This study focused on the effects of HIV-infection and chronic stress associated with childhood trauma on telomere length, and investigated whether leukocyte TL (LTL), in particular, represents a risk factor for NCI. Eighty-three HIV-positive and 45 HIV-negative women were assessed for childhood trauma and were subjected to detailed neurocognitive testing. Blood from each participant was used to extract Deoxyribonucleic acid (DNA). Relative LTL were determined by performing real time quantitative PCR reactions as described by Cawthon et al. (2002). As expected, relative LTL in the HIV-positive individuals was significantly shorter than that of HIV-negative individuals (F = 51.56, p = <0.01). Notably, a significant positive correlation was evident between relative LTL and learning performance in the HIV-positive group. In addition, a significant negative correlation was observed between relative LTL and verbal fluency, but this association was only evident in HIV-positive individuals who had experienced trauma. Our results suggest that reduced LTL is associated with worse learning performance in HIV-positive individuals, indicating that TL could act as a susceptibility factor in increasing neurocognitive decline in HIV-infected individuals. PMID:23472184

Malan-Müller, Stefanie; Hemmings, Sîan Megan Joanna; Spies, Georgina; Kidd, Martin; Fennema-Notestine, Christine; Seedat, Soraya

2013-01-01

332

Daily and Interannual Variability of Air Temperature and Precipitation As Agricultural Factor  

NASA Astrophysics Data System (ADS)

The problem investigated concerns wheat growing process sensitivity to the changes in climate variability. For the sensitivity analysis five CERES-model runs are held for three stations in Italy: Decimomannu (Sardinia), Brindisi (Apulia) and Ghedi (Padana valley, Veneto). The only difference between these five experiments for each station is a weather input. All five weather inputs for each location are simulated by weather generator WXGEN. First run ("base") is forced by weather input having tempera- ture and precipitation variance equal to the present-day values (1960-1990). Then two crop simulations are made with changed "base" interannual variance of monthly to- tal precipitation by multiplicative factors 0.5 and 2. Temperature variability remains unchanged. Last two model runs are carried out with daily halved and doubled temper- ature variance, precipitation variability is the same as in "base" simulation. Investiga- tion showed that doubled precipitation variability is accompanied at all three locations by the largest amounts of yield variability for all five scenarios. Decreased precipi- tation variability is followed by yield decline and, at the same time the amplitude of yield change is the least compared with other forcings. Decreasing of precipitation variability results in noticeably raised harvest index for the years of minimum yield. For Decimomannu and Brindisi it is almost equal to that of the maximum yield years. In general, more significantly expressed response of the yield amounts occurs for pre- cipitation variability forcings. The influence of temperature variability changes seems to be less for all three locations.

Sourkova, G.; Pona, C.

333

RNA thermometer controls temperature-dependent virulence factor expression in Vibrio cholerae  

PubMed Central

Vibrio cholerae is the bacterium that causes the diarrheal disease cholera. The bacteria experience a temperature shift as V. cholerae transition from contaminated water at lower temperatures into the 37 °C human intestine. Within the intestine, V. cholerae express cholera toxin (CT) and toxin-coregulated pilus (TCP), two main virulence factors required for disease. CT and TCP expression is controlled by the transcriptional activator protein ToxT. We identified an RNA thermometer motif in the 5? UTR of toxT, with a fourU anti-Shine-Dalgarno (SD) element that base pairs with the SD sequence to regulate ribosome access to the mRNA. RNA probing experiments demonstrated that the fourU element allowed access to the SD sequence at 37 °C but not at 20 °C. Moreover, mutations within the fourU element (U5C, U7C) that strengthened base-pairing between the anti-SD and SD sequences prevented access to the SD sequence even at 37 °C. Translation of ToxT-FLAG from the native toxT UTR was enhanced at 37 °C, compared with 25 °C in both Escherichia coli and V. cholerae. In contrast, the U5C, U7C UTR prevented translation of ToxT-FLAG even at 37 °C. V. cholerae mutants containing the U5C, U7C UTR variant were unable to colonize the infant mouse small intestine. Our results reveal a previously unknown regulatory mechanism consisting of an RNA thermometer that controls temperature-dependent translation of toxT, facilitating V. cholerae virulence at a relevant environmental condition found in the human intestine. PMID:25228776

Weber, Gregor G.; Kortmann, Jens; Narberhaus, Franz; Klose, Karl E.

2014-01-01

334

RNA thermometer controls temperature-dependent virulence factor expression in Vibrio cholerae.  

PubMed

Vibrio cholerae is the bacterium that causes the diarrheal disease cholera. The bacteria experience a temperature shift as V. cholerae transition from contaminated water at lower temperatures into the 37 °C human intestine. Within the intestine, V. cholerae express cholera toxin (CT) and toxin-coregulated pilus (TCP), two main virulence factors required for disease. CT and TCP expression is controlled by the transcriptional activator protein ToxT. We identified an RNA thermometer motif in the 5' UTR of toxT, with a fourU anti-Shine-Dalgarno (SD) element that base pairs with the SD sequence to regulate ribosome access to the mRNA. RNA probing experiments demonstrated that the fourU element allowed access to the SD sequence at 37 °C but not at 20 °C. Moreover, mutations within the fourU element (U5C, U7C) that strengthened base-pairing between the anti-SD and SD sequences prevented access to the SD sequence even at 37 °C. Translation of ToxT-FLAG from the native toxT UTR was enhanced at 37 °C, compared with 25 °C in both Escherichia coli and V. cholerae. In contrast, the U5C, U7C UTR prevented translation of ToxT-FLAG even at 37 °C. V. cholerae mutants containing the U5C, U7C UTR variant were unable to colonize the infant mouse small intestine. Our results reveal a previously unknown regulatory mechanism consisting of an RNA thermometer that controls temperature-dependent translation of toxT, facilitating V. cholerae virulence at a relevant environmental condition found in the human intestine. PMID:25228776

Weber, Gregor G; Kortmann, Jens; Narberhaus, Franz; Klose, Karl E

2014-09-30

335

Role of Factor VII in Correcting Dilutional Coagulopathy and Reducing Re-operations for Bleeding Following Non-traumatic Major Gastrointestinal and Abdominal Surgery  

PubMed Central

Objective The objective of this study is to evaluate the effectiveness of rfVIIa in reducing blood product requirements and re-operation for postoperative bleeding after major abdominal surgery. Background Hemorrhage is a significant complication after major gastrointestinal and abdominal surgery. Clinically significant bleeding can lead to shock, transfusion of blood products, and re-operation. Recent reports suggest that activated rfVIIa may be effective in correcting coagulopathy and decreasing the need for re-operation. Methods This study was a retrospective review over a 4-year period of 17 consecutive bleeding postoperative patients who received rfVIIa to control hemorrhage and avoid re-operation. Outcome measures were blood and clotting factor transfusions, deaths, thromboembolic complications, and number of re-operations for bleeding. Results Seventeen patients with postoperative hemorrhage following major abdominal gastrointestinal surgery (nine pancreas, four sarcoma, two gastric, one carcinoid, and one fistula) were treated with rfVIIa. In these 17 patients, rfVIIa was administered for 18 episodes of bleeding (dose 2,400-9,600 mcg, 29.8-100.8 mcg/kg). Transfusion requirement of pRBC and FFP were each significantly less than pre-rfVIIa. Out of the 18 episodes, bleeding was controlled in 17 (94%) without surgery, and only one patient returned to the operating room for hemorrhage. There were no deaths and two thrombotic complications. Coagulopathy was corrected by rfVIIa from 1.37 to 0.96 (p?correct dilutional coagulopathy, reducing blood product requirements and need for re-operation. PMID:20517651

Tsai, Thomas C.; Rosing, James H.

2010-01-01

336

Correct dosage of Fog2 and Gata4 transcription factors is critical for fetal testis development in mice.  

PubMed

Previous reports suggested that humans and mice differ in their sensitivity to the genetic dosage of transcription factors that play a role in early testicular development. This difference implies that testis determination might be somewhat different in these two species. We report that the Fog2 and Gata4 transcription factors are haploinsufficient for testis determination in mice. Whether gonadal sex reversal occurs depends on genetic background (i.e., modifier genes). For example, C57BL/6J (B6) XY mice develop testes if they are heterozygous for a mutant Fog2 (Fog2-) or Gata4 (Gata4(ki)) allele. However, if the B6 Y chromosome (Y(B6)) is replaced by the AKR Y chromosome (Y(AKR)), B6 Fog2-/+ XY(AKR) mice develop ovaries, and B6 Gata4(ki)/+ XY(AKR) mice develop ovaries and ovotestes (gonads containing both ovarian and testicular tissue). Furthermore, DBA/2J (D2) Fog2-/+ XY(AKR) mice and (B6 x D2)F1 hybrid Gata4(ki)/+ XY(AKR) mice develop testes. Sry is expressed in the mutant XY gonads, indicating that the lack of Sry expression is not the cause of ovarian tissue development in B6 Fog2-/+ or Gata4(ki)/+ XY(AKR) mice. However, up-regulation of Sox9 expression, which is critical for normal testicular development, does not occur in mutant XY gonads that develop as ovaries. We conclude that under certain genetic conditions, Sox9 up-regulation depends on the proper dosage of Fog2 and Gata4. We propose that in humans the FOG2 and/or GATA4 genes might be haploinsufficient for normal testis determination and thus could be the cause of some previously unassigned cases of XY gonadal sex reversal. PMID:17848526

Bouma, Gerrit J; Washburn, Linda L; Albrecht, Kenneth H; Eicher, Eva M

2007-09-18

337

ECOC comparison exercise with identical thermal protocols after temperature offsets correction - instrument diagnostics by in-depth evaluation of operational parameters  

NASA Astrophysics Data System (ADS)

A comparison exercise on thermal-optical elemental carbon/organic carbon (ECOC) analyzers was carried out among 17 European laboratories. Contrary to previous comparison exercises, the 17 participants made use of an identical instrument set-up, after correcting for temperature offsets with the application of a recently developed temperature calibration kit (Sunset Laboratory Inc, OR, US). Five filter samples and two sucrose solutions were analyzed with both the EUSAAR2 and NIOSH870 thermal protocols. z Scores were calculated for total carbon (TC) and nine outliers and three stragglers were identified. Three outliers and eight stragglers were found for EC. Overall, the participants provided results within the warning levels with the exception of two laboratories that showed poor performance, the causes of which were identified and corrected through the course of the comparison exercise. The TC repeatability and reproducibility relative standard deviations were 11.4 and 14.6% for EUSAAR2 and 9.2 and 11.7% for NIOSH870; the standard deviations for EC were 15.3 and 19.5% for EUSAAR2 and 19.9 and 25.5% for NIOSH870. TC was in good agreement between the two protocols, TCNIOSH870 = 0.98 · TCEUSAAR2 (R2 = 1.00, normalized means). Transmittance (TOT) calculated EC for NIOSH870 was found to be 20% lower than for EUSAAR2, ECNIOSH870 = 0.80 · ECEUSAAR2 (R2 = 0.96, normalized means). The thermograms and laser signal values were compared and similar peak patterns were observed per sample and protocol for most participants. Notable deviations of plotted values indicated absence or inaccurate application of the temperature calibration procedure and/or pre-oxidation during the inert phase of the analysis. Low or no pyrolytic organic carbon (POC), as reported by a few participants, is suggested as an indicator of pre-oxidation. A sample-specific pre-oxidation effect was observed for filter G, for all participants and both thermal protocols, indicating the presence of oxygen donors on the suspended particulate matter. POC (TOT) levels were lower for NIOSH870 than for EUSAAR2, which is related to the heating profile differences of the two thermal protocols.

Panteliadis, P.; Hafkenscheid, T.; Cary, B.; Diapouli, E.; Fischer, A.; Favez, O.; Quincey, P.; Viana, M.; Hitzenberger, R.; Vecchi, R.; Maggos, T.; Sciare, J.; Jaffrezo, J. L.; John, A.; Schwarz, J.; Giannoni, M.; Novak, J.; Karanasiou, A.; Fermo, P.; Maenhaut, W.

2014-08-01

338

Evaluation of Wall Correction Factor of INER's Air-Kerma Primary Standard Chamber and Dose Variation by Source Displacement for HDR 192Ir Brachytherapy  

PubMed Central

The aim of the present study was to estimate the wall effect of the self-made spherical graphite-walled cavity chamber with the Monte Carlo method for establishing the air-kerma primary standard of high-dose-rate (HDR) 192Ir brachytherapy sources at the Institute of Nuclear Energy Research (INER, Taiwan). The Monte Carlo method established in this paper was also employed to respectively simulate wall correction factors of the 192Ir air-kerma standard chambers used at the National Institute of Standards and Technology (NIST, USA) and the National Physical Laboratory (NPL, UK) for comparisons and verification. The chamber wall correction calculation results will be incorporated into INER's HDR 192Ir primary standard in the future. For the brachytherapy treatment in the esophagus or in the bronchi, the position of the isotope may have displacement in the cavity. Thus the delivered dose would differ from the prescribed dose in the treatment plan. We also tried assessing dose distribution due to the position displacement of HDR 192Ir brachytherapy source in a phantom with a central cavity by the Monte Carlo method. The calculated results could offer a clinical reference for the brachytherapy within the human organs with cavity. PMID:24222907

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

2013-01-01

339

Development of correction factors for NO2 EMEP emission fluxes using the GEM-AQ model simulations and satellite observations from OMI and SCIAMACHY.  

NASA Astrophysics Data System (ADS)

A simple method for correcting NO2 emissions that employs an air quality model results and satellite observations from OMI and SCIAMACHY will be presented. A 3 year (2008-2010) air quality model simulation over Europe was undertaken. The GEM-AQ model using EMEP emissions was run on a global variable resolution grid centered over Europe with spacing of ~15 km (0.125ox 0.125o) in the core. Monthly mean NO2 tropospheric columns were calculated using hourly model results. Monthly averaged NO2 tropospheric columns for the 2008-2010 were compared with OMI and SCIAMACHY tropospheric products. This simple method based on differences between model and satellite data allowed to define regions with systematic over and underestimations of the modelled NO2 columns. Results from this work allow for the development of emission correction factors that can be applied to NO2 emissions fluxes for individual SNAP sectors. The GEM-AQ model simulations were done for 2011 using adjusted emission fluxes. Monthly averaged tropospheric columns were compared with available satellite products for 2011.

Szymankiewicz, Karol; Kaminski, Jacek W.; Struzewska, Joanna

2014-05-01

340

Exposure levels due to WLAN devices in indoor environments corrected by a time-amplitude factor of distribution of the quasi-stochastic signals.  

PubMed

With the development of radiofrequency technology, radiating quasi-stochastic signals like the wireless local area networks (WLAN), a proper procedure of exposure level assessment is needed. No standardised procedure exists at the moment. While channel power measurement proved to overestimate the field strength, weighting techniques were proposed. The paper compares the exposure levels determined by three different procedures, two of them correcting the field level by weighting. Twenty-three experimental cases of WLAN traffic load are analysed in an indoor environment in controlled conditions. The results show the differences obtained when the duty cycle (DC) method is applied comparatively with the application of weighting based on an amplitude-time correction. Significant exposure level reductions of 52.6-79.2 % from the field determined by frequency domain method and of 36.5-72.8 % from the field determined by the DC weighting method were obtained by time-amplitude method. Specificities of weighting factors probability density functions were investigated and regression analysis was applied for a detailed characterisation of this procedure. PMID:24591729

Miclaus, Simona; Bechet, Paul; Stratakis, Dimitrios

2014-12-01

341

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 climatic conditions and geohazards is required to help prepare for future events. To this end, Norwegian authorities initiated an interdisciplinary research project, called "GeoExtreme". By studying the climatic conditions of historic geohazards, GeoExtreme is establishing relationships between climate variables and geohazards. Following these studies, GeoExtreme will endeavor to forecast geohazard scenarios using state-of-the-art climate change projection models and to assess the socio-economic consequences of future geohazards (Jaedicke et. al., 2008). The work presented here, carried out under the GeoExtreme project, is focused specifically on the effect of rainfall and temperature on rockslides and rockfalls in the southwestern coastal counties of Hordaland and Sogn og Fjordane in Norway. The Norwegian Geotechnical Institute (NGI) has provided an inventory of 3,595 rockslide events, recorded by the Norwegian Road and Rail Authorities, that have been recorded in the area since 1963. In order to study the effects of climate on these historic slides, the Norwegian Meteorological Institute (met.no) has examined precipitation and temperature data from local weather stations to interpolate the climatic conditions at each rockslide location on the day and the days preceding the event. As a result, each rockslide in the database includes climate variables such as temperature, accumulated precipitation of one to several days, degree-days, and frost cycles. The rockslide database comes with some constraints. Rockslides in the region have been recorded by Transportation Authorities. As a consequence, the data is only available along road or railway corridors. Rockslides that occur away from transportation infrastructure are not recorded and hence the dataset contains substantial spatial data discontinuity. There is also a temporal variance in the data. The county of Sogn og Fjordane has been recording rockslides semi-frequently since the 1970's, but there is a distinct increase in rockslide incidence in 1997, as recording procedures became more detailed and comprehensive. The county of Hordaland had very infrequent recording of rockslides prior to 2000, but since then has kept a very detailed rockslide inventory. Research completed thus far includes statistical analyses to establish relationships between the rockslides and their corresponding climate variables. Preliminary results indicate that short-term antecedent rainfall (less than 7 days before the event) and freeze-thaw cycles have the most important effect on the triggering of rockslides in the region. In fact, a high proportion of rockslides occur when these conditions occur simultaneously, when warm Atlantic storms make landfall during the cold winter months. These storms bring intense rainfall and raise temperatures above freezing levels, thus creating high runoff conditions. This ongoing research includes the study of historical storm events to gain a better understanding of the precise climatic conditions required to initiate rockslides. A primary goal of this research is to use geographic information system (GIS) technology to complete a rockslide hazard susceptibility map of the study area. A statistical approach is proposed, including many of the traditional factors (i.e. layers) used to generate hazard maps, such as: slope angle, slope curvature, geology, land use, etc. Factors related to climate will also be included as trends become apparent from the data analysis described above. It is expected that elevation, distance from the coast, and pro

Dunlop, S.; Hutchinson, D. J.

2009-04-01

342

Toward accurate thermochemistry of the (24)MgH, (25)MgH, and (26)MgH molecules at elevated temperatures: corrections due to unbound states.  

PubMed

The total partition functions QT and their first two moments Q(')T and Q(?)T, together with the isobaric heat capacities CpT, are computed a priori for three major MgH isotopologues on the temperature range of T = 100-3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to QT at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q(?)T and CpT, principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of (24)MgH, (25)MgH, and (26)MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species. PMID:25573549

Szidarovszky, Tamás; Császár, Attila G

2015-01-01

343

Toward accurate thermochemistry of the 24MgH, 25MgH, and 26MgH molecules at elevated temperatures: Corrections due to unbound states  

NASA Astrophysics Data System (ADS)

The total partition functions Q(T) and their first two moments Q ' (T) and Q ? (T), together with the isobaric heat capacities C p (T), are computed a priori for three major MgH isotopologues on the temperature range of T = 100-3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to Q (T) at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q ? (T) and C p (T), principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of 24MgH, 25MgH, and 26MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species.

Szidarovszky, Tamás; Császár, Attila G.

2015-01-01

344

Structure of hydrothermal convection in the Upper Rhine Graben as inferred from corrected temperature data and basin-scale numerical models  

NASA Astrophysics Data System (ADS)

Geothermal anomalies in sedimentary basins are strongly controlled by fluid circulation within permeable zones. Exploration of new targets requires the understanding of how and why hydrothermal circulation patterns establish in a particular zone. This study presents a new compilation of newly corrected bottom-hole temperature data in the French part of the Upper Rhine Graben, where the Soultz-sous-Forêts temperature anomaly is locked beneath a local horst structure. After a geostatistically constrained interpolation procedure, maps and cross-sections are extracted from the 3D thermal block, together with the associated standard deviations. Thermal anomalies are preferentially associated with the thickest zones of the permeable fractured Buntsandstein (sandstones) formation, in apparent contradiction with previous models where two major fault zones were suggested to control fluid flow. The underlying fractured granitic basement hosts fluid circulation patterns which are apparently controlled at large-scale by the inclined basement-sediments interface. Based on these observations, numerical models of hydrothermal convection including an inclined basement-sediments interface, a local horst structure, and realistic petrophysical properties have been carried out. The depth-decrease of permeability, the inclination of the interface and the fixed heat flow condition at the base of the model, explain why only a few upwellings can be triggered. Thermal anomalies and a measured temperature profile can be reproduced when fault permeability equals 10- 14 m2. Interestingly, structure of convective patterns also exhibits a second and hotter upwelling, in the Rittershoffen area, 8 km east of the Soultz-sous-Forêts upwelling zone, where another geothermal exploration project is now underway. The understanding of hydrothermal convection with realistic fluid and rock properties clearly appears as a predictive tool for geothermal exploration strategies.

Guillou-Frottier, Laurent; Carr?, Clément; Bourgine, Bernard; Bouchot, Vincent; Genter, Albert

2013-04-01

345

Characterization of radiation beams used to determinate the correction factor for a CyberKnife® unit reference field using ionization chambers  

NASA Astrophysics Data System (ADS)

This paper aimed to characterize a 6 MV x-ray beam from a Varian® iX linear accelerator in order to obtain the correction factors needed by the IAEA/AAPM new formalism1. The experiments were performed in a liquid water phantom under different irradiation conditions: a) Calibration of the reference field of 10 cm × 10 cm at 90 cm SSD and 10 cm depth was carried out according to the TRS-398 protocol using three ionization chambers (IC) calibrated in different reference laboratory and b) Measurement of the absorbed dose rate at 70 cm SSD and 10 cm depth in a 10 cm × 10 cm and 5.4 cm × 5.4 cm fields was obtained in order to simulate the CyberKnife® conditions where maximum distance between the source and the detector is equal to 80 cm and the maximum field size is 6 cm diameter. Depending where the IC was calibrated, differences between 0.16% and 2.24% in the absorbed dose rate measured in the 10 cm × 10 cm field at 90 cm SSD were observed, while for the measurements at 70 cm SSD, differences between 1.27% and 3.88% were obtained. For the 5.4 cm × 5.4 cm field, the absorbed dose measured with the three ICs varies between 1.37% and 3.52%. The increase in the difference on the absorbed dose when decreasing the SSD could possibly be associated to scattering radiation generated from the collimators and/or the energy dependence of the ionization chambers to low-energy radiation. The results presented in this work suggest the importance of simulating the CyberKnife® conditions using other linear accelerator for obtaining the correction factors as proposed by the IAEA/AAPM new formalism in order to measure the absorbed dose with acceptable accuracy.

Aragón-Martínez, Nestor; Gómez-Muñoz, Arnulfo; Massillon-JL, Guerda

2014-11-01

346

Correction of systematic model forcing bias of CLM using assimilation of cosmic-ray Neutrons and land surface temperature: a study in the Heihe Catchment, China  

NASA Astrophysics Data System (ADS)

The recent development of the non-invasive cosmic-ray soil moisture sensing technique fills the gap between point-scale soil moisture measurements and regional-scale soil moisture measurements by remote sensing. A cosmic-ray probe measures soil moisture for a footprint with a diameter of ~ 600 m (at sea level) and with an effective measurement depth between 12 and 76 cm, depending on the soil humidity. In this study, it was tested whether neutron counts also allow correcting for a systematic error in the model forcings. A lack of water management data often causes systematic input errors to land surface models. Here, the assimilation procedure was tested for an irrigated corn field (Heihe Watershed Allied Telemetry Experimental Research - HiWATER, 2012) where no irrigation data were available as model input although for the area a significant amount of water was irrigated. In the study, the measured cosmic-ray neutron counts and Moderate-Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) products were jointly assimilated into the Community Land Model (CLM) with the local ensemble transform Kalman filter. Different data assimilation scenarios were evaluated, with assimilation of LST and/or cosmic-ray neutron counts, and possibly parameter estimation of leaf area index (LAI). The results show that the direct assimilation of cosmic-ray neutron counts can improve the soil moisture and evapotranspiration (ET) estimation significantly, correcting for lack of information on irrigation amounts. The joint assimilation of neutron counts and LST could improve further the ET estimation, but the information content of neutron counts exceeded the one of LST. Additional improvement was achieved by calibrating LAI, which after calibration was also closer to independent field measurements. It was concluded that assimilation of neutron counts was useful for ET and soil moisture estimation even if the model has a systematic bias like neglecting irrigation. However, also the assimilation of LST helped to correct the systematic model bias introduced by neglecting irrigation and LST could be used to update soil moisture with state augmentation.

Han, X.; Franssen, H.-J. H.; Rosolem, R.; Jin, R.; Li, X.; Vereecken, H.

2015-01-01

347

Far-infrared-detected Lyman-break galaxies at z ~ 3. Dust attenuation and dust correction factors at high redshift  

NASA Astrophysics Data System (ADS)

Lyman-break galaxies (LBGs) represent one of the kinds of star-forming galaxies that are found in the high-redshift universe. The detection of LBGs in the far-infrared (FIR) domain can provide very important clues on their dust attenuation and total star-formation rate (SFR), allowing a more detailed study than has been performed so far. In this work we explore the FIR emission of a sample of 16 LBGs at z ~ 3 in the GOODS-North and GOODS-South fields that are individually detected in PACS-100 ?m or PACS-160 ?m. These detections demonstrate the possibility of measuring the dust emission of LBGs at high redshift. We find that PACS-detected LBGs at z ~ 3 are highly obscured galaxies which belong to the ultra-luminous or hyper-luminous IR galaxy class. Their total SFR cannot be recovered with the dust attenuation factors obtained from their UV continuum slope or their SED-derived dust attenuation employing Bruzual & Charlot (2003) templates. Both methods underestimate the results for most of the galaxies. Comparing with a sample of PACS-detected LBGs at z ~ 1, we find evidence that the FIR emission of LBGs might have changed with redshift, in the sense that the dustiest LBGs found at z ~ 3 have more prominent FIR emission, are dustier for a given UV slope, and have higher SFR for a given stellar mass than the dustiest LBGs found at z ~ 1. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A is available in electronic form at http://www.aanda.org

Oteo, I.; Cepa, J.; Bongiovanni, Á.; Pérez-García, A. M.; Cedrés, B.; Domínguez Sánchez, H.; Ederoclite, A.; Sánchez-Portal, M.; Pintos-Castro, I.; Pérez-Martínez, R.

2013-06-01

348

The Role of Column Calibration Factor in the Study of Temperature Dependence of Thermal Diffusion Factor of Hydrogenic Trace Mixtures with Helium  

NASA Astrophysics Data System (ADS)

The variation of column calibration factor Fs with respect to temperature change has been attained for a given column (C.J.G. Slieker and A. E. de Vries: J. Chim. Phys. 60 (1963) 172) to estimate the temperature dependence of thermal diffusion factor ?T of trace mixtures of hydrogenic isotopes in helium only to detect the existence of inelastic collision effect in the mixtures as predicted by T. K. Chattopadhyay and S. Acharyya (J. Phys. B 7 (1974) 2277). Attempts have also been made to interpret the ?T’s thus obtained in terms of the available elastic and inelastic collision theories of thermal diffusion to establish the importance of the column calibration factor in column measurements.

Acharyya, S.; Saha, I. L.; Datta, A. K.; Chatterjee, A. K.

1987-01-01

349

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; Treviño, Rodolfo J; Valvano, Jonathan W; Pearce, John A; Feldman, Marc D

2009-12-01

350

Factorize  

NSDL National Science Digital Library

Visualize factors through building rectangular areas on a grid. First enter all the factorizations of a number, then draw each factor set as an area on the grid. Factorize is one of the Interactivate assessment explorers.

351

Factors controlling corrosion in high-temperature aqueous solutions: a contribution to the dissociation and solubility data influencing corrosion processes  

Microsoft Academic Search

Typical materials for applications in high-temperature, high-pressure aqueous solutions are stainless steels, nickel-base alloys, titanium, tantalum, noble metals, or ceramics. Under these conditions, these materials are often severely attacked, especially in the presence of acids, salts, or gases.Corrosion phenomena in high-temperature aqueous solutions are mainly influenced by the following factors: dissociation of acids, salts, and bases, the solubility of gases,

P. Kritzer; N. Boukis; E. Dinjus

1999-01-01

352

High-Temperature Protein G Is an Essential Virulence Factor of Leptospira interrogans  

PubMed Central

Leptospira interrogans is a global zoonotic pathogen and is the causative agent of leptospirosis, an endemic disease of humans and animals worldwide. There is limited understanding of leptospiral pathogenesis; therefore, further elucidation of the mechanisms involved would aid in vaccine development and the prevention of infection. HtpG (high-temperature protein G) is the bacterial homolog to the highly conserved molecular chaperone Hsp90 and is important in the stress responses of many bacteria. The specific role of HtpG, especially in bacterial pathogenesis, remains largely unknown. Through the use of an L. interrogans htpG transposon insertion mutant, this study demonstrates that L. interrogans HtpG is essential for virulence in the hamster model of acute leptospirosis. Complementation of the htpG mutant completely restored virulence. Surprisingly, the htpG mutant did not appear to show sensitivity to heat or oxidative stress, phenotypes common in htpG mutants in other bacterial species. Furthermore, the mutant did not show increased sensitivity to serum complement, reduced survival within macrophages, or altered protein or lipopolysaccharide expression. The underlying cause for attenuation thus remains unknown, but HtpG is a novel leptospiral virulence factor and one of only a very small number identified to date. PMID:24366253

King, Amy M.; Pretre, Gabriela; Bartpho, Thanatchaporn; Sermswan, Rasana W.; Toma, Claudia; Suzuki, Toshihiko; Eshghi, Azad; Picardeau, Mathieu; Murray, Gerald L.

2014-01-01

353

Improving source identification of Atlanta aerosol using temperature resolved carbon fractions in positive matrix factorization  

NASA Astrophysics Data System (ADS)

Daily integrated PM 2.5 (particulate matter ?2.5 ?m in aerodynamic diameter) composition data including eight individual carbon fractions collected at the Jefferson Street monitoring site in Atlanta were analyzed with positive matrix factorization (PMF). Particulate carbon was analyzed using the thermal optical reflectance method that divides carbon into four organic carbon (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. A total of 529 samples and 28 variables were measured between August 1998 and August 2000. PMF identified 11 sources in this study: sulfate-rich secondary aerosol I (50%), on-road diesel emissions (11%), nitrate-rich secondary aerosol (9%), wood smoke (7%), gasoline vehicle (6%), sulfate-rich secondary aerosol II (6%), metal processing (3%), airborne soil (3%), railroad traffic (3%), cement kiln/carbon-rich (2%), and bus maintenance facility/highway traffic (2%). Differences from previous studies using only the traditional OC and EC data (J. Air Waste Manag. Assoc. 53(2003a)731; Atmos Environ. (2003b)) include four traffic-related combustion sources (gasoline vehicle, on-road diesel, railroad, and bus maintenance facility) containing carbon fractions whose abundances were different between the various sources. This study indicates that the temperature resolved fractional carbon data can be utilized to enhance source apportionment study, especially with respect to the separation of diesel emissions from gasoline vehicle sources. Conditional probability functions using surface wind data and identified source contributions aid the identifications of local point sources.

Kim, Eugene; Hopke, Philip K.; Edgerton, Eric S.

354

Dust correction factors over 0 < z < 3 in massive star-forming galaxies derived from a stacking analysis of Herschel data  

NASA Astrophysics Data System (ADS)

We use a stacking analysis in Herschel/PACS to study the accuracy of several dust-correction factors that are typically employed to estimate the total star-formation rate (SFR) of high-redshift, massive, star-forming (SF) galaxies. We also analyze what stacking suggests about the relation between SFR and stellar mass and the redshift evolution of the specific SFR (sSFR = SFR/M?). We find that the dust properties of massive SF galaxies evolve with redshift, that is, galaxies at z ~ 2-3 are more attenuated than at z ~ 1 for a given UV continuum slope and stellar mass. As a consequence, a single IRX-? or dust-mass relation cannot be used to recover the total SFR of massive SF galaxies at 0 ? z ? 3. This might have implications for studies at higher redshifts, where a single IRX-? relation derived for local starbursts is usually assumed to be valid. However, we find evidence that the local relations might be valid at least up to z ~ 1, where bluer and less massive galaxies can be detected through stacking. The spectral energy distribution fitting procedure with stellar population templates gives overestimated values (about 0.3-0.5 dex in log SFR) of the dust-corrected SFR at all redshifts studied here. We find that the slope of the main-sequence of star formation is flatter than previously found in massive galaxies with log (M?/M?) ? 10, and the redshift evolution of the sSFR reported in previous works in massive galaxies is well recovered. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A is available in electronic form at http://www.aanda.org

Oteo, I.

2014-12-01

355

Factoring  

NSDL National Science Digital Library

Test your factoring skills Factors and Multiples Jeopardy How much do you know about factoring and multiples? Play Jeopardy and find out! Prime Factoring Turkey Shoot Blast these turkeys using your factoring skills. Help the Professor Super save the planet by "cooking" the Giant Frozen Turkeys of Destruction. Math Lines 12 X-Factor Shoot the ball at the other factors to get a product of 12. You can also ...

Mr Clark

2012-10-31

356

Temperature  

NSDL National Science Digital Library

This topic in depth begins with the About Temperature (1) Web site, written by Beverly T. Lynds of Unidata, which is a program that works to enable university researchers and educators to acquire and use atmospheric and related data. The one-page site explains what temperature is, the development of thermometers, heat and thermodynamics, and other related topics. The second site is maintained by the University of Execter's Centre for Innovation in Mathematics Teaching. Actually an online tool called Conversion Calculator for Units of Temperature (2), the site allows users to type in any value, choose a significant figure, press "convert it," and get that value in Kelvin, Celsius, Fahrenheit, r'aumur, and rankine units. The next site is a lesson plan from AskEric.com entitled Temperature: Is it Hot or Cold? (3). Written for 2nd graders, the lesson demonstrates to how to read thermometers, determine their rise or fall, record temperatures, and take temperatures of various items. The fourth site, Surface Temperature Analysis (4), is presented by NASA's Goddard Institute for Space Studies. Here, visitors can view graphs, maps, animations, and station data of global surface temperatures. For example, the animation covers 12-month means from 1971 to 1999. The History Behind the Thermometer (5) Web site, from About.com, explores what a thermometer is, how it works, and how it came into being. The sixth site, entitled Science Shack (6) and offered by the BBC, answers the question, Why do we have two different temperature scales, Celsius and Fahrenheit? The site explains how to create your own thermometer like Galileo's, tells how it works, and why we use other types today. The next site is provided by National Oceanic and Atmospheric Administration (NOAA) and presents US State temperature extremes and drought information (7). Visitors can see all-time temperature maximums and minimums by state, monthly temperatures by state, and more. The last site is an all-inclusive temperature site called Temperature World (8). Everything from news, science, organizations, general interest, games, and more -- all related to temperature -- can be found here.

Brieske, Joel A.

357

Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature.  

PubMed

Sky view factor (SVF), which is an indicator of urban canyon geometry, affects the surface energy balance, local air circulation, and outdoor thermal comfort. This study focused on a continuous and long-term meteorological observation system to investigate the effects of SVF on outdoor thermal conditions and physiological equivalent temperature (PET) in the central business district (CBD) of Beijing (which is located within Chaoyang District), specifically addressed current knowledge gaps for SVF-PET relationships in cities with typical continental/microthermal climates. An urban sub-domain scale model and the RayMan model were used to diagnose wind fields and to calculate SVF and long-term PET, respectively. Analytical results show that the extent of shading contributes to variations in thermal perception distribution. Highly shaded areas (SVF <0.3) typically exhibit less frequent hot conditions during summer, while enduring longer periods of cold discomfort in winter than moderately shaded areas (0.3< SVF <0.5) and slightly shaded areas (SVF >0.5), and vice versa. Because Beijing has a monsoon-influenced humid continental climate with hot summers and long, cold, windy, and dry winters, a design project that ideally provides moderate shading should be planned to balance hot discomfort in summer and cold discomfort in winter, which effectively prolongs the comfort periods in outdoor spaces throughout the entire year. This research indicate that climate zone characteristics, urban environmental conditions, and thermal comfort requirements of residents must be accounted for in local-scale scientific planning and design, i.e., for urban canyon streets and residential estates. PMID:24842520

He, Xiaodong; Miao, Shiguang; Shen, Shuanghe; Li, Ju; Zhang, Benzhi; Zhang, Ziyue; Chen, Xiujie

2015-03-01

358

Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature  

NASA Astrophysics Data System (ADS)

Sky view factor (SVF), which is an indicator of urban canyon geometry, affects the surface energy balance, local air circulation, and outdoor thermal comfort. This study focused on a continuous and long-term meteorological observation system to investigate the effects of SVF on outdoor thermal conditions and physiological equivalent temperature (PET) in the central business district (CBD) of Beijing (which is located within Chaoyang District), specifically addressed current knowledge gaps for SVF-PET relationships in cities with typical continental/microthermal climates. An urban sub-domain scale model and the RayMan model were used to diagnose wind fields and to calculate SVF and long-term PET, respectively. Analytical results show that the extent of shading contributes to variations in thermal perception distribution. Highly shaded areas (SVF <0.3) typically exhibit less frequent hot conditions during summer, while enduring longer periods of cold discomfort in winter than moderately shaded areas (0.3< SVF <0.5) and slightly shaded areas (SVF >0.5), and vice versa. Because Beijing has a monsoon-influenced humid continental climate with hot summers and long, cold, windy, and dry winters, a design project that ideally provides moderate shading should be planned to balance hot discomfort in summer and cold discomfort in winter, which effectively prolongs the comfort periods in outdoor spaces throughout the entire year. This research indicate that climate zone characteristics, urban environmental conditions, and thermal comfort requirements of residents must be accounted for in local-scale scientific planning and design, i.e., for urban canyon streets and residential estates.

He, Xiaodong; Miao, Shiguang; Shen, Shuanghe; Li, Ju; Zhang, Benzhi; Zhang, Ziyue; Chen, Xiujie

2014-05-01

359

Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature  

NASA Astrophysics Data System (ADS)

Sky view factor (SVF), which is an indicator of urban canyon geometry, affects the surface energy balance, local air circulation, and outdoor thermal comfort. This study focused on a continuous and long-term meteorological observation system to investigate the effects of SVF on outdoor thermal conditions and physiological equivalent temperature (PET) in the central business district (CBD) of Beijing (which is located within Chaoyang District), specifically addressed current knowledge gaps for SVF-PET relationships in cities with typical continental/microthermal climates. An urban sub-domain scale model and the RayMan model were used to diagnose wind fields and to calculate SVF and long-term PET, respectively. Analytical results show that the extent of shading contributes to variations in thermal perception distribution. Highly shaded areas (SVF <0.3) typically exhibit less frequent hot conditions during summer, while enduring longer periods of cold discomfort in winter than moderately shaded areas (0.3< SVF <0.5) and slightly shaded areas (SVF >0.5), and vice versa. Because Beijing has a monsoon-influenced humid continental climate with hot summers and long, cold, windy, and dry winters, a design project that ideally provides moderate shading should be planned to balance hot discomfort in summer and cold discomfort in winter, which effectively prolongs the comfort periods in outdoor spaces throughout the entire year. This research indicate that climate zone characteristics, urban environmental conditions, and thermal comfort requirements of residents must be accounted for in local-scale scientific planning and design, i.e., for urban canyon streets and residential estates.

He, Xiaodong; Miao, Shiguang; Shen, Shuanghe; Li, Ju; Zhang, Benzhi; Zhang, Ziyue; Chen, Xiujie

2015-03-01

360

An improved temperature index model for alpine glaciers using derived degree-day factors from climatic inputs  

NASA Astrophysics Data System (ADS)

Glacier melt rates are strongly affected by minor perturbations in climatic systems. Quantifying changes in glacier melt rates is therefore important, particularly in areas where melt-water contributes to hydroelectric power generation, irrigation, or flood risks. Several methods currently exist for modeling glacier melt rates, but one widely used method is temperature index modeling, also called positive degree-day modeling. This model is often applied due to its simplicity and small number of input variables, but it still depends on an empirically-measured scaling constant (the degree-day factor). These degree-day factors can vary by a factor of five from one glacier to the next, complicating the applicability of the approach to new regions, or to different time periods. Previous work suggests the degree-day factor may be a function of the surface albedo, solar radiation, and near-surface air temperature. Thus, it is possible the degree-day factor itself is predictable. In this study we present a method to derive these melt factors directly from easily obtained climatic variables, thus allowing for the ready application of temperature index modeling to a much wider suite of glaciers with greater accuracy. We used a full energy-balance model to calculate possible degree-day factors over the full range of climate conditions commonly encountered with alpine glaciers. We then constructed a statistical emulator (a linear model which considers numerous interactions and polynomial effects) using select climate variables (insolation, positive degree-days, and albedo) as inputs. The statistical model is tuned using the energy-balance output as training data. The model skill will be tested against a suite of empirically-derived degree-day factors. These results would allow for the application of more accurate glacier melt models with quantified uncertainties to under-sampled glacial regions and paleoclimate reconstructions.

Keeler, D. G.; Havens, A. P.; Rupper, S.; Christensen, W. F.

2013-12-01

361

Trends in 1970-2010 summertime coastal California air temperatures:how HCN-corrections to COOP-data eliminated coastal-cooling  

NASA Astrophysics Data System (ADS)

The analysis of California COOP-site monthly-averaged summer Tmax-trends (1970-2005) by Lebassi et al. (2009, in J. of Climate) has been extended by: (a) lengthening the period to 2010, (b) trend-comparisons with newly released HCN data, and (c) calculation of trends in annual Tmax-values. HCN data sets are NCDC-homogenized subsets of the "most trusted" COOP sites; they include 12 (of the 52 COOP sites) in the San Francisco Bay Area and four (of 28) in the Southern California Air Basin (SoCAB). COOP data used as HCN1 data were adjusted by NCDC for the following biases: (a) time-of-observations, (b) spatial inhomogeneity, (c) missing values, (d) changes in thermometer type, and (e) urban warming, while HCN2 data do not include the last two corrections. Comparison of the 35- and 40-year COOP monthly-averaged Tmax-trends at the 16 HCN sites showed a high correlation (0.96). It also showed, however, that as the six inland warming-sites (COOP sites also HCN sites) of Lebassi et al. are now generally warming a slightly lower rate than five years ago, the seven comparable coastal-cooling sites are thus now generally cooling at a slightly lower rate. Coastal-cooling was shown by Lebassi et al. as a "reverse-reaction" to regional warming in inland areas, which triggers coastal sea breezes, and which thus increased cooling onshore flows. Comparison of HCN1 and COOP 35-year Tmax-trends shows little correlation (0.15), as the HCN1-corrections changed six of the seven COOP cooling-sites into HCN1 warming-sites. Only the site with largest original COOP cooling also showed HCN1 cooling. Similar comparisons between the COOP and HCN2 sites showed that HCN2-corrections changed fewer (only four) cooling-sites to warming (and with lower warming-rates); a low correlation (0.44) thus existed between trend-values. As many climate-change impacts (e.g., brown outs, heat stress, ozone peaks) depend on extreme Tmax-values, and not just averaged-monthly Tmax-values, the SoCAB distribution of the highest COOP Tmax-values anytime (at each of its 28 sites) during the period from 1970-2010 shows three sub-areas, with a boundary-temperature of 340C (and with the following ranges): (a) cool coastal (27-340C), (b) cool mountain-tops (28-340C), and (c) in-between hot-area (34-400C). The spatial distribution of the trends in these extreme Tmax-values show decreases up to -0.80C/dec in the coastal cooling areas and increases up to 0.60C/dec in the inland and mountain warming areas. Note that these trends are larger than the monthly-averaged Tmax-trends (about ±0.30C/dec) in Lebassi et al.

Bornstein, R. D.; Ghebreegziabher, A. T.; Lebassi, B.; González, J. E.

2011-12-01

362

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

363

Temperature  

NSDL National Science Digital Library

This article discusses the relationship between temperature and heat and kinetic energy and it shows how to convert from degrees Fahrenheit to Centigrade. It also includes links to other resources, data, maps, and classroom activities.

2008-04-08

364

Complete and sustained phenotypic correction of hemophilia B in mice following hepatic gene transfer of a high-expressing human factor IX plasmid.  

PubMed

Therapeutic correction of hemophilia B was achieved by rapid infusion of a large-volume solution containing a high-expressing human factor IX (hFIX) plasmid into the tail vein of hemophilia B mice. hFIX circulated at therapeutic levels (1-5 micro g mL-1) in all animals for more than 1 year as determined by both species-specific antigen assay and an activated partial thromboplastin time (APTT)-based clotting assay. There was acute, transient hepatic tissue damage by the infusion procedure and no significant inhibitory anti-hFIX antibodies developed. No bleeding episode was observed during or after treatment. Immunohistochemical studies indicated that the hFIX gene was exclusively expressed in hepatocytes, and that transduced cells had readily detectable hFIX protein at 4 h postinfusion, and stainable protein persisted for up to 1 year. Repeated infusions of hFIX plasmids boosted the hFIX expression to higher levels. These results demonstrate that hemophilia B can be treated by gene transfer of naked hFIX plasmids. PMID:12871546

Ye, X; Loeb, K R; Stafford, D W; Thompson, A R; Miao, C H

2003-01-01

365

[Temperature as an autoecological factor of chitinolytic microbial complex formation in soils].  

PubMed

The dynamics of carbon dioxide emission from soil was studied during chitinolytic succession induced by humidification and chitin introduction at different temperatures (5, 27, and 50 degrees C) using gas chromatography. The abundance and biomass of the chitinolytic bacterial and actinomycete complex in soil were evaluated by luminescent microscopy. Active development of the chitinolytic microbial complexes was observed at all studied temperatures. The most active growth of chitinolytic microorganisms was observed at high temperature during early succession and at low temperature during late succession. High and low temperatures provided for active development of the chitinolytic microbial complex in soils confined to warm climatic zones (brown desert-steppe soil) and soils of temporary zones (gray forest soil). Actinomycetes demonstrated the most active growth among chitinolytic microorganisms in the studied soil samples both at low and high temperatures.. PMID:17665647

Manucharova, N A; Vlasenko, A N; Stepanov, A L

2007-01-01

366

Factors influencing stream temperatures in small streams: substrate effects and a shading experiment  

Microsoft Academic Search

The temperature of stream water is an important control of many in-stream processes. To better understand the processes and consequences of solar energy inputs to streams, stream temperature dynamics were examined before, during, and after experimental shading of a 150-m reach of a second-order stream in the Oregon Cascade Range. Maxi- mum water temperatures declined significantly in the shaded reach,

Sherri L. Johnson

2004-01-01

367

Thermal form factors of the XXZ chain and the large-distance asymptotics of its temperature dependent correlation functions  

NASA Astrophysics Data System (ADS)

We derive expressions for the form factors of the quantum transfer matrix of the spin-\\frac{1}{2} XXZ chain which are suitable for taking the infinite Trotter number limit. These form factors determine the finitely many amplitudes in the leading asymptotics of the finite-temperature correlation functions of the model. We consider form factor expansions of the longitudinal and transversal two-point functions. Remarkably, the formulae for the amplitudes are in both cases of the same form. We also explain how to adapt our formulae to the description of ground-state correlation functions of the finite chain. The usefulness of our novel formulae is demonstrated by working out explicit results in the high- and low-temperature limits. We obtain, in particular, the large-distance asymptotics of the longitudinal two-point functions for small temperatures by summing up the asymptotically most relevant terms in the form factor expansion of a generating function of the longitudinal correlation functions. As expected, the leading term in the expansion of the corresponding two-point functions is in accordance with conformal field theory predictions. Here it is obtained for the first time by a direct calculation.

Dugave, Maxime; Göhmann, Frank; Kozlowski, Karol K.

2013-07-01

368

A hypothesis about factors that affect maximum stream temperatures across montane landscapes  

USGS Publications Warehouse

Temperature is an important variable structuring lotic biotas, but little is known about how montane landscapes function to determine stream temperatures. We developed an a priori hypothesis that was used to predict how watershed elements would interact to affect stream temperatures. The hypothesis was tested in a series of path analyses using temperature data from 26 sites on second-order to fourth-order streams across a fifth-order Rocky Mountain watershed. Based on the performance of the first hypothesis, two revised versions of the hypothesis were developed and tested that proved to be more accurate than the original hypothesis. The most plausible of the revised hypotheses accounted for 82 percent of the variation in maximum stream temperature, had a predicted data structure that did not deviate from the empirical data structure, and was the most parsimonious. The final working hypothesis suggested that stream temperature maxima were directly controlled by a large negative effect from mean basin elevation (direct effect = -0.57, p < 0.01) and smaller effects from riparian tree abundance (direct effect = -0.28, p = 0.03), and cattle density (direct effect = 0.24, p = 0.05). Watershed slope, valley constraint, and the abundance of grass across a watershed also affected temperature maxima, but these effects were indirect and mediated through cattle density and riparian trees. Three variables included in the a priori hypothesis - watershed aspect, stream width, and watershed size - had negligible effects on maximum stream temperatures and were omitted from the final working hypothesis.

Isaak, D.J.; Hubert, W.A.

2001-01-01

369

SUMMER STREAM TEMPERATURES, JUVENILE COHO CONDITION FACTORS AND BLACK SPOT INFECTION IN THE OREGON COAST RANGE  

EPA Science Inventory

We monitored stream temperatures at 35 locations throughout the West Fork Smith River watershed in the Oregon Coast Range during the summer of 2002. Between July 24 and August 24, maximum seven-day moving average high daily temperatures ranged from 21.8 C near the catchment's mo...

370

Effect of design factors on surface temperature and wear in disk brakes  

NASA Technical Reports Server (NTRS)

The temperatures, friction, wear and contact conditions that occur in high energy disk brakes are studied. Surface and near surface temperatures were monitored at various locations in a caliper disk brake during drag type testing, with friction coefficient and wear rates also being determined. The recorded transient temperature distributions in the friction pads and infrared photographs of the rotor disk surface both showed that contact at the friction surface was not uniform, with contact areas constantly shifting due to nonuniform thermal expansion and wear. The effect of external cooling and of design modifications on friction, wear and temperatures was also investigated. It was found that significant decreases in surface temperature and in wear rate can be achieved without a reduction in friction either by slotting the contacting face of the brake pad or by modifying the design of the pad support to improve pad compliance. Both design changes result in more uniform contact conditions on the friction surface.

Santini, J. J.; Kennedy, F. E.; Ling, F. F.

1976-01-01

371

Dominant factors affecting temperature rise in simulations of human thermoregulation during RF exposure.  

PubMed

Numerical models of the human thermoregulatory system can be used together with realistic voxel models of the human anatomy to simulate the body temperature increases caused by the power absorption from radio-frequency electromagnetic fields. In this paper, the Pennes bioheat equation with a thermoregulatory model is used for calculating local peak temperatures as well as the body-core-temperature elevation in a realistic human body model for grounded plane-wave exposures at frequencies 39, 800 and 2400 MHz. The electromagnetic power loss is solved by the finite-difference time-domain (FDTD) method, and the discretized bioheat equation is solved by the geometric multigrid method. Human thermoregulatory models contain numerous thermophysiological and computational parameters--some of which may be subject to considerable uncertainty--that affect the simulated core and local temperature elevations. The goal of this paper is to find how greatly the computed temperature is influenced by changes in various modelling parameters, such as the skin blood flow rate, models for vasodilation and sweating, and clothing and air movement. The results show that the peak temperature rises are most strongly affected by the modelling of tissue blood flow and its temperature dependence, and mostly unaffected by the central control mechanism for vasodilation and sweating. Almost the opposite is true for the body-core-temperature rise, which is however typically greatly lower than the peak temperature rise. It also seems that ignoring the thermoregulation and the blood temperature increase is a good approximation when the local 10 g averaged specific absorption rate is smaller than 10 W kg(-1). PMID:22080753

Laakso, Ilkka; Hirata, Akimasa

2011-12-01

372

Dominant factors affecting temperature rise in simulations of human thermoregulation during RF exposure  

NASA Astrophysics Data System (ADS)

Numerical models of the human thermoregulatory system can be used together with realistic voxel models of the human anatomy to simulate the body temperature increases caused by the power absorption from radio-frequency electromagnetic fields. In this paper, the Pennes bioheat equation with a thermoregulatory model is used for calculating local peak temperatures as well as the body-core-temperature elevation in a realistic human body model for grounded plane-wave exposures at frequencies 39, 800 and 2400 MHz. The electromagnetic power loss is solved by the finite-difference time-domain (FDTD) method, and the discretized bioheat equation is solved by the geometric multigrid method. Human thermoregulatory models contain numerous thermophysiological and computational parameters—some of which may be subject to considerable uncertainty—that affect the simulated core and local temperature elevations. The goal of this paper is to find how greatly the computed temperature is influenced by changes in various modelling parameters, such as the skin blood flow rate, models for vasodilation and sweating, and clothing and air movement. The results show that the peak temperature rises are most strongly affected by the modelling of tissue blood flow and its temperature dependence, and mostly unaffected by the central control mechanism for vasodilation and sweating. Almost the opposite is true for the body-core-temperature rise, which is however typically greatly lower than the peak temperature rise. It also seems that ignoring the thermoregulation and the blood temperature increase is a good approximation when the local 10 g averaged specific absorption rate is smaller than 10 W kg-1.

Laakso, Ilkka; Hirata, Akimasa

2011-12-01

373

Temperature  

NASA Technical Reports Server (NTRS)

The problems in human comfort in heat stress are emphasized, with less emphasis placed upon cold exposure problems. Physiological parameters related to human thermal interactions are discussed, as well as data concerning thermal protective clothing. The energy balance equation, heat transfer equation, thermal comfort, heat stress, and cold stress are also considered. A two node model of human temperature regulation in FORTRAN is appended.

Berenson, P. J.; Robertson, W. G.

1973-01-01

374

Heat shock factor gene family in rice: genomic organization and transcript expression profiling in response to high temperature, low temperature and oxidative stresses.  

PubMed

Binding of heat shock factors (HSFs) with heat shock element sequence is critical for the transcriptional induction of heat shock genes. Rice genome sequence shows 26 OsHsf genes out of which 25 possess various important domains noted in HSFs i.e. DNA binding domain (DBD), oligomerization domain (OD), nuclear localization signal (NLS), nuclear export signal (NES) and AHA type activation domain. OsHsf entry LOC_Os06g226100 has the oligomerization domain but lacks the above other domains. Also, there are no ESTs or full-length cDNA noted for this entry in database. Expression profiling showed that 22 OsHsf genes are induced by high temperature. Induction of 10 and 14 OsHsf genes was also noted against low temperature stress and oxidative stress, respectively. All OsHsf genes induced by oxidative stress were also induced by high temperature. On the other hand, induction of 6 and 1 OsHsf genes was noted to be exclusive to high and low temperature stresses, respectively. Seven OsHsf genes showed induced expression in response to all the three stresses examined. While in silico promoter analysis showed that OsHsf genes contain upstream regulatory elements corresponding to different abiotic stresses, there was lack of correlation noted between the in silico profiling of the elements and their corresponding transcript expression patterns. Apart from stress inducibility, EST database suggests that various OsHsf genes are developmentally regulated in diverse tissue types. PMID:19539489

Mittal, Dheeraj; Chakrabarti, Sveta; Sarkar, Anshuk; Singh, Amanjot; Grover, Anil

2009-09-01

375

Resource Supply Overrides Temperature as a Controlling Factor of Marine Phytoplankton Growth  

PubMed Central

The universal temperature dependence of metabolic rates has been used to predict how ocean biology will respond to ocean warming. Determining the temperature sensitivity of phytoplankton metabolism and growth is of special importance because this group of organisms is responsible for nearly half of global primary production, sustains most marine food webs, and contributes to regulate the exchange of CO2 between the ocean and the atmosphere. Phytoplankton growth rates increase with temperature under optimal growth conditions in the laboratory, but it is unclear whether the same degree of temperature dependence exists in nature, where resources are often limiting. Here we use concurrent measurements of phytoplankton biomass and carbon fixation rates in polar, temperate and tropical regions to determine the role of temperature and resource supply in controlling the large-scale variability of in situ metabolic rates. We identify a biogeographic pattern in phytoplankton metabolic rates, which increase from the oligotrophic subtropical gyres to temperate regions and then coastal waters. Variability in phytoplankton growth is driven by changes in resource supply and appears to be independent of seawater temperature. The lack of temperature sensitivity of realized phytoplankton growth is consistent with the limited applicability of Arrhenius enzymatic kinetics when substrate concentrations are low. Our results suggest that, due to widespread resource limitation in the ocean, the direct effect of sea surface warming upon phytoplankton growth and productivity may be smaller than anticipated. PMID:24921945

Marañón, Emilio; Cermeño, Pedro; Huete-Ortega, María; López-Sandoval, Daffne C.; Mouriño-Carballido, Beatriz; Rodríguez-Ramos, Tamara

2014-01-01

376

Temperature as an autoecological factor of chitinolytic microbial complex formation in soils  

Microsoft Academic Search

The dynamics of carbon dioxide emission from soil was studied during chitinolytic succession induced by humidification and\\u000a chitin introduction at different temperatures (5, 27, and 50C) using gas chromatography. The abundance and biomass of the\\u000a chitinolytic bacterial and actinomycete complex in soil were evaluated by luminescent microscopy. Active development of the\\u000a chitinolytic microbial complexes was observed at all studied temperatures.

N. A. Manucharova; A. N. Vlasenko; A. L. Stepanov

2007-01-01

377

Factors affecting temperature variation and habitat use in free-ranging diamondback terrapins.  

PubMed

Measuring the thermal conditions of aquatic reptiles with temperature dataloggers is a cost-effective way to study their behavior and habitat use. Temperature dataloggers are a particularly useful and informative approach to studying organisms such as the estuarine diamondback terrapin (Malaclemys terrapin) that inhabits a dynamic environment often inaccessible to researchers. We used carapace-mounted dataloggers to measure hourly carapace temperature (Tc) of free-ranging terrapins in South Carolina from October 2007 to 2008 to examine the effects of month, sex, creek site, and tide on Tc and to determine the effects of month, sex, and time of day on terrapin basking frequency. Simultaneous measurements of environmental temperatures (Te; shallow mud, deep mud, water) allowed us to make inferences about terrapin microhabitat use. Terrapin Tc differed significantly among months and creek and between sexes. Terrapin microhabitat use also varied monthly, with shallow mud temperature being the best predictor of Tc November-March and water temperature being the best predictor of Tc April-October. Terrapins basked most frequently in spring and fall and males basked more frequently than females. Our study contributes to a fuller understanding of terrapin thermal biology and provides support for using dataloggers to investigate behavior and habitat use of aquatic ectotherms inhabiting dynamic environments. PMID:25086975

Akins, C D; Ruder, C D; Price, S J; Harden, L A; Gibbons, J W; Dorcas, M E

2014-08-01

378

Deconvolving temperature and substrate effects on soil heterotrophic respiration under multiple global change factors in mixed grass prairie  

NASA Astrophysics Data System (ADS)

The temperature sensitivity of soil organic matter (SOM) decomposition exposed to elevated CO2 and warming represents a substantial source of uncertainty in predicting climate-carbon feedbacks. Here, we evaluated temperature responses of soil heterotrophic respiration via soil laboratory incubations at the Prairie Heating and CO2 Enrichment experiment. Soils were collected from plots with and without native vegetation so as to examine plant-mediated effects on temperature sensitivity of SOM decomposition under simulated climate change. Thus, soils were exposed to full factorial combinations of elevated CO2, warming and vegetation removal for four years prior to sampling. Incubations were conducted for 60 days at optimal water content (60% of field capacity) and 15, 22 or 30 °C. Total soil C content was measured prior to the start of incubations, and soil respiration was measured 11 times throughout the incubation. Data were analyzed in the context of a Bayesian model where respiration of the fast (aka ';labile') and slow (aka ';recalcitrant') soil C pools were determined by separate Arrhenius-type temperature sensitivity functions as well as by the pool size. We tested competing hypotheses that differences in soil heterotrophic respiration under the different treatments could be explained by 1) changes in the exponential temperature sensitivity (Q10), 2) changes in the base rate, or 3) changes in the size of the fast and slow pools. The model predictions fit the observed data well (r2 = 0.93) across all treatments. The Q10 of both the fast and slow pools decreased ~40% between the 15 and 30 °C incubation temperature across all treatment levels. The Q10 of the fast pool was lower in the warmed treatment than the control in both fallow and vegetated soils, consistent with thermal acclimation. The Q10 of the fast pool under elevated CO2 and warming was lowest in the fallow soil, but highest in the vegetated soil. This indicates that rhizosphere priming plays a role in temperature sensitivity of SOM decomposition. Overall, the temperature sensitivity of the fast pool was highly sensitive to global change factors and their interactions. On the other hand, there were no differences in temperature sensitivity of the slow pool in response to the global change factors. Similarly, the base rate of the fast pool was sensitive to the global change factors, while the slow pool base rate was not. However, the overall size of the slow pool was significantly affected by the global change factors. Vegetation removal reduced the slow pool by ~19% across all warming x CO2 treatments. This effect was greatest under elevated CO2 (both warmed and control), but non-significant under ambient CO2 and temperature. Importantly, effects mediated through the vegetation were the primary factor determining whether slow pool C was gained or lost under elevated CO2 and warming. Our data-model fusion approach allowed us to deconvolve the effect of reduced substrate availability from temperature sensitivity, and to demonstrate that global change may lead to strong positive C cycling feedbacks.

Tucker, C.; Nie, M.; Pendall, E. G.

2013-12-01

379

Role of Hot Water System Design on Factors Influential to Pathogen Regrowth: Temperature, Chlorine Residual, Hydrogen Evolution, and Sediment.  

PubMed

Residential water heating is linked to growth of pathogens in premise plumbing, which is the primary source of waterborne disease in the United States. Temperature and disinfectant residual are critical factors controlling increased concentration of pathogens, but understanding of how each factor varies in different water heater configurations is lacking. A direct comparative study of electric water heater systems was conducted to evaluate temporal variations in temperature and water quality parameters including dissolved oxygen levels, hydrogen evolution, total and soluble metal concentrations, and disinfectant decay. Recirculation tanks had much greater volumes of water at temperature ranges with potential for increased pathogen growth when set at 49°C compared with standard tank systems without recirculation. In contrast, when set at the higher end of acceptable ranges (i.e., 60°C), this relationship was reversed and recirculation systems had less volume of water at risk for pathogen growth compared with conventional systems. Recirculation tanks also tended to have much lower levels of disinfectant residual (standard systems had 40-600% higher residual), 4-6 times as much hydrogen, and 3-20 times more sediment compared with standard tanks without recirculation. On demand tankless systems had very small volumes of water at risk and relatively high levels of disinfectant residual. Recirculation systems may have distinct advantages in controlling pathogens via thermal disinfection if set at 60°C, but these systems have lower levels of disinfectant residual and greater volumes at risk if set at lower temperatures. PMID:24170969

Brazeau, Randi H; Edwards, Marc A

2013-10-01

380

Role of Hot Water System Design on Factors Influential to Pathogen Regrowth: Temperature, Chlorine Residual, Hydrogen Evolution, and Sediment  

PubMed Central

Abstract Residential water heating is linked to growth of pathogens in premise plumbing, which is the primary source of waterborne disease in the United States. Temperature and disinfectant residual are critical factors controlling increased concentration of pathogens, but understanding of how each factor varies in different water heater configurations is lacking. A direct comparative study of electric water heater systems was conducted to evaluate temporal variations in temperature and water quality parameters including dissolved oxygen levels, hydrogen evolution, total and soluble metal concentrations, and disinfectant decay. Recirculation tanks had much greater volumes of water at temperature ranges with potential for increased pathogen growth when set at 49°C compared with standard tank systems without recirculation. In contrast, when set at the higher end of acceptable ranges (i.e., 60°C), this relationship was reversed and recirculation systems had less volume of water at risk for pathogen growth compared with conventional systems. Recirculation tanks also tended to have much lower levels of disinfectant residual (standard systems had 40–600% higher residual), 4–6 times as much hydrogen, and 3–20 times more sediment compared with standard tanks without recirculation. On demand tankless systems had very small volumes of water at risk and relatively high levels of disinfectant residual. Recirculation systems may have distinct advantages in controlling pathogens via thermal disinfection if set at 60°C, but these systems have lower levels of disinfectant residual and greater volumes at risk if set at lower temperatures. PMID:24170969

Brazeau, Randi H.; Edwards, Marc A.

2013-01-01

381

Stable and temperature-sensitive transformation of rat kidney epithelial cells suppresses expression of acidic fibroblast growth factor 1 but activates secretion of fibroblast growth factor 3 (int-2) and vascular endothelial growth factor.  

PubMed

Rat kidney proximal tubule epithelial cells (RPTE) in primary culture express acidic fibroblast growth factor 1 (FGF-1). Transformation of RPTE by SV40 (SV-RPTE) suppressed FGF-1 expression but activated secretion of FGF-like factor(s). SV-RPTE conditioned medium contained growth-promoting activity for SV-RPTE and human umbilical vein endothelial cells, indicating that both autocrine and angiogenic factors were secreted. Reverse transcriptase-polymerase chain reaction and Northern analysis for various FGFs showed that only FGF-3, also known as int-2, mRNA was expressed in SV-RPTE. In addition, expression of mRNA for the heparin-binding angiogenic factor vascular endothelial growth factor (VEGF) increased dramatically in SV-RPTE. Physical characterization of the activity in the SV-RPTE conditioned medium suggested that FGF-3 and VEGF contributed the autocrine and angiogenic activities, respectively. We also investigated FGF-3 and VEGF secretion in temperature-sensitive (ts) SV40-transformed RPTE. tsSV-RPTE had transformed properties resembling those of SV-RPTE only at the permissive temperature (33 degrees C), e.g., increased growth potential and anchorage-independent growth. FGF-1 was expressed only at the nonpermissive temperature. VEGF mRNA levels and secretion of the human umbilical vein endothelial cell growth-promoting activity were reduced by switching tsSV-RPTE cells from 33 degrees to 39 degrees C. However, FGF-3 mRNA levels were not affected significantly by the temperature switch suggesting that activation of VEGF and FGF-3 occurs through different mechanisms. These results indicate that FGF-1 expression in RPTE is suppressed by SV40 transformation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7519042

Zhang, G; Sato, J D; Herley, M T; Tsang, M W; Ye, H; Liu, H; Ichimura, T; Yan, G; McKeehan, W L; Stevens, J L

1994-04-01

382

Ambient temperature: a factor affecting performance and physiological response of broiler chickens  

NASA Astrophysics Data System (ADS)

An experiment was conducted to elucidate the influence of four constant ambient temperatures (20°, 25°, 30° and 35°C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20°, 25°, 30° and 35°C treatments showed highly significant ( P<0.0001) depression in growth rate, food intake and efficiency of food utilization, and a significant increase in water consumption for the 30° and 35°C groups. Mortality was, however, not affected by the temperature treatments. Changes in physiological status, such as increased rectal temperatures, decreased concentration of red blood cells, haemoglobin, haematocrit, and total plasma protein were observed in birds housed in the higher temperature (30° and 35°C) environments. Moreover, in these broiler chickens, there was an increased blood glucose concentration and a decreased thyroid gland weight. These results indicate that continuous exposure of broiler chickens to high ambient temperatures markedly affects their performance and physiological response.

Donkoh, A.

1989-12-01

383

The effects of incomplete annealing on the temperature dependence of sheet resistance and gage factor in aluminum and phosphorus implanted silicon on sapphire  

NASA Technical Reports Server (NTRS)

Partial annealing of damage to the crystal lattice during ion implantation reduces the temperature coefficient of resistivity of ion-implanted silicon, while facilitating controlled doping. Reliance on this method for temperature compensation of the resistivity and strain-gage factor is discussed. Implantation conditions and annealing conditions are detailed. The gage factor and its temperature variation are not drastically affected by crystal damage for some crystal orientations. A model is proposed to account for the effects of electron damage on the temperature dependence of resistivity and on silicon piezoresistance. The results are applicable to the design of silicon-on-sapphire strain gages with high gage factors.

Pisciotta, B. P.; Gross, C.

1976-01-01

384

Factorize  

NSDL National Science Digital Library

This interactive applet allows a student to visually explore the concept of factors by creating different rectangular arrays for a number. The user constructs the array by clicking and dragging on a grid. The length and width of the array are factors of the number. A student can elect an option of a randomly selected number or the student selects his own number between 2 and 50. Exploration questions are included to promote student discovery of mathematical concepts with factors.

2000-01-01

385

Uncovering Different Masking Factors on Wrist Skin Temperature Rhythm in Free-Living Subjects  

PubMed Central

Most circadian rhythms are controlled by a major pacemaker located in the hypothalamic suprachiasmatic nucleus. Some of these rhythms, called marker rhythms, serve to characterize the timing of the internal temporal order. However, these variables are susceptible to masking effects as the result of activity, body position, light exposure, environmental temperature and sleep. Recently, wrist skin temperature (WT) has been proposed as a new index for evaluating circadian system status. In light of previous evidence suggesting the important relationship between WT and core body temperature regulation, the aim of this work was to purify the WT pattern in order to obtain its endogenous rhythm with the application of multiple demasking procedures. To this end, 103 subjects (18–24 years old) were recruited and their WT, activity, body position, light exposure, environmental temperature and sleep were recorded under free-living conditions for 1 week. WT demasking by categories or intercepts was applied to simulate a “constant routine” protocol (awakening, dim light, recumbent position, low activity and warm environmental temperature). Although the overall circadian pattern of WT was similar regardless of the masking effects, its amplitude was the rhythmic parameter most affected by environmental conditions. The acrophase and mesor were determined to be the most robust parameters for characterizing this rhythm. In addition, a circadian modulation of the masking effect was found for each masking variable. WT rhythm exhibits a strong endogenous component, despite the existence of multiple external influences. This was evidenced by simultaneously eliminating the influence of activity, body position, light exposure, environmental temperature and sleep. We therefore propose that it could be considered a valuable and minimally-invasive means of recording circadian physiology in ambulatory conditions. PMID:23577201

Martinez-Nicolas, Antonio; Ortiz-Tudela, Elisabet; Rol, Maria Angeles; Madrid, Juan Antonio

2013-01-01

386

Comparison of models for the free-free Gaunt factor at low temperatures and frequencies  

SciTech Connect

We perform calculations for the free-free Gaunt factor at electron and photon energies below 1 Ry in the dipole approximation to the radiation field for a variety of representations of the scattering potential. We consider the static-exchange, static-exchange + model polarization, model exchange, and static models. Within each model, the resulting Schroedinger equation is solved exactly using a linear algebraic prescription. We investigate the rare gas and alkali systems. We find great sensitivity to the models for energies below four electron volts (4 eV). Above this energy, the Gaunt factors for the various models come into better agreement. 31 refs., 3 figs., 1 tab.

Collins, L.A.; Merts, A.L.

1985-01-01

387

Combined influence of chemical and physical factors upon coal particle temperature profiles during rapid heating pyrolysis  

Microsoft Academic Search

In order to numerically determine the effect of chemical and physical parameters upon particle temperature profiles during pyrolysis, a basic composition model of coal itself needs to be postulated. It is desirable to make the model as straightforward and general as possible in order to more clearly ascertain the effects of systematic parametric changes upon results. Keeping the model initially

J. D. Freihaut; A. A. Leff; F. J. Vastola

1977-01-01

388

Estradiol and Incubation Temperature Modulate Regulation of Steroidogenic Factor 1 in the Developing  

E-print Network

hormones, including estrogen, are not thought to be involved in primary sex determination of mammals (3, 4 for sex deter- mination, with incubation temperature of the egg determining go- nadal sex. At higher biosynthesis from cholesterol. In mammals as well as red-eared slider turtles, SF-1 is differentially expressed

Crews, David

389

Ambient temperature: a factor affecting performance and physiological response of broiler chickens  

Microsoft Academic Search

An experiment was conducted to elucidate the influence of four constant ambient temperatures (20°, 25°, 30° and 35°C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20°, 25°,

A. Donkoh

1989-01-01

390

Physiological fluctuations in brain temperature as a factor affecting electrochemical evaluations of extracellular glutamate and glucose in behavioral experiments.  

PubMed

The rate of any chemical reaction or process occurring in the brain depends on temperature. While it is commonly believed that brain temperature is a stable, tightly regulated homeostatic parameter, it fluctuates within 1-4 °C following exposure to salient arousing stimuli and neuroactive drugs, and during different behaviors. These temperature fluctuations should affect neural activity and neural functions, but the extent of this influence on neurochemical measurements in brain tissue of freely moving animals remains unclear. In this Review, we present the results of amperometric evaluations of extracellular glutamate and glucose in awake, behaving rats and discuss how naturally occurring fluctuations in brain temperature affect these measurements. While this temperature contribution appears to be insignificant for glucose because its extracellular concentrations are large, it is a serious factor for electrochemical evaluations of glutamate, which is present in brain tissue at much lower levels, showing smaller phasic fluctuations. We further discuss experimental strategies for controlling the nonspecific chemical and physical contributions to electrochemical currents detected by enzyme-based biosensors to provide greater selectivity and reliability of neurochemical measurements in behaving animals. PMID:23448428

Kiyatkin, Eugene A; Wakabayashi, Ken T; Lenoir, Magalie

2013-05-15

391

Monte Carlo study of correction factors for Spencer-Attix cavity theory at photon energies at or above 100 keV.  

PubMed

To develop a primary standard for 192Ir sources, the basic science on which this standard is based, i.e., Spencer-Attix cavity theory, must be established. In the present study Monte Carlo techniques are used to investigate the accuracy of this cavity theory for photons in the energy range from 20 to 1300 keV, since it is usually not applied at energies below that of 137Cs. Ma and Nahum [Phys. Med. Biol. 36, 413-428 (1991)] found that in low-energy photon beams the contribution from electrons caused by photons interacting in the cavity is substantial. For the average energy of the 192Ir spectrum they found a departure from Bragg-Gray conditions of up to 3% caused by photon interactions in the cavity. When Monte Carlo is used to calculate the response of a graphite ion chamber to an encapsulated 192Ir source it is found that it differs by less than 0.3% from the value predicted by Spencer-Attix cavity theory. Based on these Monte Carlo calculations, for cavities in graphite it is concluded that the Spencer-Attix cavity theory with delta = 10 keV is applicable within 0.5% for photon energies at 300 keV or above despite the breakdown of the assumption that there is no interaction of photons within the cavity. This means that it is possible to use a graphite ion chamber and Spencer-Attix cavity theory to calibrate an 192Ir source. It is also found that the use of delta related to the mean chord length instead of delta = 10 keV improves the agreement with Spencer-Attix cavity theory at 60Co from 0.2% to within 0.1% of unity. This is at the level of accuracy of which the Monte Carlo code EGSnrc calculates ion chamber responses. In addition, it is shown that the effects of other materials, e.g., insulators and holders, have a substantial effect on the ion chamber response and should be included in the correction factors for a primary standard of air kerma. PMID:10984227

Borg, J; Kawrakow, I; Rogers, D W; Seuntjens, J P

2000-08-01

392

Growth, condition factor, and bioenergetics modeling link warmer stream temperatures below a small dam to reduced performance of juvenile steelhead  

USGS Publications Warehouse

We investigated the growth and feeding performance of juvenile steelhead Oncorhynchus mykiss using field measures and bioenergetics modeling. Juvenile steelhead populations were sampled from mid-June through August 2004 at study sites upstream and downstream of Hemlock Dam. The growth and diet of juvenile steelhead were determined for a warm (summer) and subsequent (late summer) transitional period at each study site. Empirical data on the growth and diet of juvenile steelhead and mean daily temperatures were used in a bioenergetics model to estimate the proportion of maximum consumption achieved by juvenile steelhead by site and period. Modeled estimates of feeding performance were better for juvenile steelhead at the upstream compared to the downstream site during both periods. The median condition factor of juvenile steelhead did not change over the summer at the upstream site, but showed a significant decline over time at the downstream site. A negative trend in median condition factor at the downstream site supported bioenergetics modeling results that suggested the warmer stream temperatures had a negative impact on juvenile steelhead. Bioenergetics modeling predicted a lower feeding performance for juvenile steelhead rearing downstream compared to upstream of Hemlock Dam although food availability appeared to be limited at both study sites during the warm period. Warmer water temperatures, greater diel variation, and change in diel pattern likely led to the reduced feeding performance and reduced growth, which could have affected the overall survival of juvenile steelhead downstream of Hemlock Dam. ?? 2010 by the Northwest Scientific Association.

Sauter, S.T.; Connolly, P.J.

2010-01-01

393

Re-evaluation of correction factors of a primary standard graphite calorimeter in 60Co gamma ray beams as a basis for the appointment of the BEV absorbed dose rate to water reference value.  

PubMed

The graphite calorimeter of the Federal Office of Metrology and Surveying (BEV-Bundesamt für Eich- und Vermessungswesen) was established in the 1980s as the primary standard for the absorbed dose to water for (60)Co gamma ray beams. To maintain the primary standard at an international level the graphite calorimeter and its corresponding components had to undergo a refurbishment and modernisation process. The correction factors of the graphite calorimeter were re-evaluated with Monte Carlo and experimental methods to obtain improved values. These are the correction for the effect of the gaps (1.0061), the scaling correction (0.9998), the correction for the difference in air attenuation (0.9971) and the corrections for the effective measurement depths in the graphite phantom for the graphite calorimeter (0.9886) and the CC01-105 ionisation chamber (0.9913). Consequently, it was necessary to change the reference value for the absorbed dose rate to water of the (60)Co teletherapy unit used for the calibration of secondary standard dosemeters. PMID:21112889

Baumgartner, Andreas; Steurer, Andreas; Tiefenböck, Wilhelm; Gabris, Frantisek; Maringer, Franz Josef; Kapsch, Ralf-Peter; Stucki, Gerhard

2011-04-01

394

Assessment of factors limiting Klamath River fall Chinook salmon production potential using historical flows and temperatures  

USGS Publications Warehouse

We parameterized and applied a deterministic salmon production model to infer the degree to which river flows and temperatures may limit freshwater production potential of the Klamath River in California. Specific parameter requirements, data sources, and significant assumptions are discussed in detail. Model simulations covered a wide variety of historical hydrologic and meteorologic conditions for 40+ years of environmental data. The model was calibrated only qualitatively, appearing to perform well in predicted outmigrant timing, but overestimating growth. Egg-to-outmigrant survival was near that reported for other rivers north of the Klamath River. Predicted production potential appeared to be determined by multiple causes involving both regularly occurring habitat-related constraints and irregularly occurring exposure to high water temperatures. Simulated production was greatest in years of intermediate water availability and was constrained in both dry and wet years, but for different reasons. Reducing mortality associated with limitations to juvenile habitat, if possible, would be expected to have the highest payoff in increasing production. Water temperature was important in determining predicted production in some years but overall was not predicted to be as important as physical microhabitat. No single mortality cause acted as a true a??bottlenecka?? on productiona?|

Bartholow, John M.; Henriksen, James A.

2006-01-01

395

Calibration factor of track etch detectors at different temperatures of water  

E-print Network

. LR 115 Type 2 Response to Alpha Particles. . . . Calculation for the Calibration Factor . 21 . 23 . 27 . . . 30 . . . 34 III METHODS AND MATERIALS 36 Radium Standard . Radon Source Liquid Scintillation Calibration and Radon Concentration... and Jordana 1987). The average US groundwater concentration is in the range of 200- 600 pCi/L The concentration of radon in public groundwater supplies is a thousand times higher than uranium or radium, probably due to the absorption of the radium...

Yasmeen, Nuzhat

1997-01-01

396

Factors  

NSDL National Science Digital Library

This lesson is designed to develop students' abilities to find factors of whole numbers. The lesson also introduces prime numbers. This lesson provides links to discussions and activities related to factors as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one. Note, reading level is not indicated because the lesson does not include student reading material.

2011-05-24

397

Factoring  

NSDL National Science Digital Library

In this lesson we will explore prime numbers and factors A prime number has only two factors, 1 and itself. The Greek scholar, Eratosthenes of Cyrene lived from approximately 275 to 195 BC. He is know for being the first to have computed the size of the Earth and served as the director of the famous library in

Mrs. Taylor

2010-10-19

398

Single-crystal sapphire resonator at millikelvin temperatures: Observation of thermal bistability in high-Q factor whispering gallery modes  

SciTech Connect

Resonance modes in single crystal sapphire ({alpha}-Al{sub 2}O{sub 3}) exhibit extremely high electrical and mechanical Q factors ({approx_equal}10{sup 9} at 4 K), which are important characteristics for electromechanical experiments at the quantum limit. We report the cool down of a bulk sapphire sample below superfluid liquid-helium temperature (1.6 K) to as low as 25 mK. The electromagnetic properties were characterized at microwave frequencies, and we report the observation of electromagnetically induced thermal bistability in whispering gallery modes due to the material T{sup 3} dependence on thermal conductivity and the ultralow dielectric loss tangent. We identify ''magic temperatures'' between 80 and 2100 mK, the lowest ever measured, at which the onset of bistability is suppressed and the frequency-temperature dependence is annulled. These phenomena at low temperatures make sapphire suitable for quantum metrology and ultrastable clock applications, including the possible realization of the quantum-limited sapphire clock.

Creedon, Daniel L.; Tobar, Michael E.; Le Floch, Jean-Michel; Reshitnyk, Yarema; Duty, Timothy [School of Physics (M013), University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009 (Australia); School of Mathematics and Physics, University of Queensland, St. Lucia, Queensland 4072 (Australia)

2010-09-01

399

Genetically distinct populations of northern shrimp, Pandalus borealis, in the North Atlantic: adaptation to different temperatures as an isolation factor.  

PubMed

The large-scale population genetic structure of northern shrimp, Pandalus borealis, was investigated over the species' range in the North Atlantic, identifying multiple genetically distinct groups. Genetic divergence among sample localities varied among 10 microsatellite loci (range: FST  = -0.0002 to 0.0475) with a highly significant average (FST  = 0.0149; P < 0.0001). In contrast, little or no genetic differences were observed among temporal replicates from the same localities (FST  = 0.0004; P = 0.33). Spatial genetic patterns were compared to geographic distances, patterns of larval drift obtained through oceanographic modelling, and temperature differences, within a multiple linear regression framework. The best-fit model included all three factors and explained approximately 29% of all spatial genetic divergence. However, geographic distance and larval drift alone had only minor effects (2.5-4.7%) on large-scale genetic differentiation patterns, whereas bottom temperature differences explained most (26%). Larval drift was found to promote genetic homogeneity in parts of the study area with strong currents, but appeared ineffective across large temperature gradients. These findings highlight the breakdown of gene flow in a species with a long pelagic larval phase (up to 3 months) and indicate a role for local adaptation to temperature conditions in promoting evolutionary diversification and speciation in the marine environment. PMID:25782085

Jorde, Per Erik; Søvik, Guldborg; Westgaard, Jon-Ivar; Albretsen, Jon; André, Carl; Hvingel, Carsten; Johansen, Torild; Sandvik, Anne Dagrun; Kingsley, Michael; Jørstad, Knut Eirik

2015-04-01

400

The time of day differently influences fatigue and locomotor activity: is body temperature a key factor?  

PubMed

The aim of this study was to verify the possible interactions between exercise capacity and spontaneous locomotor activity (SLA) during the oscillation of core body temperature (Tb) that occurs during the light/dark cycle. Wistar rats (n=11) were kept at an animal facility under a light/dark cycle of 14/10h at an ambient temperature of 23°C and water and food ad libitum. Initially, in order to characterize the daily oscillation in SLA and Tb of the rats, these parameters were continuously recorded for 24h using an implantable telemetric sensor (G2 E-Mitter). The animals were randomly assigned to two progressive exercise test protocols until fatigue during the beginning of light and dark-phases. Fatigue was defined as the moment rats could not keep pace with the treadmill. We assessed the time to fatigue, workload and Tb changes induced by exercise. Each test was separated by 3days. Our results showed that exercise capacity and heat storage were higher during the light-phase (p<0.05). In contrast, we observed that both SLA and Tb were higher during the dark-phase (p<0.01). Notably, the correlation analysis between the amount of SLA and the running capacity observed at each phase of the daily cycle revealed that, regardless of the time of the day, both types of locomotor physical activity have an important inherent component (r=0.864 and r=0.784, respectively, p<0.01) without a direct relationship between them. This finding provides further support for the existence of specific control mechanisms for each type of physical activity. In conclusion, our data indicate that the relationship between the body temperature and different types of physical activity might be affected by the light/dark cycle. These results mean that, although exercise performance and spontaneous locomotor activity are not directly associated, both are strongly influenced by daily cycles of light and dark. PMID:25479573

Machado, Frederico Sander Mansur; Rodovalho, Gisele Vieira; Coimbra, Cândido Celso

2015-03-01

401

The effect of temperature on the formation resistivity factor of porous media  

E-print Network

!. racting the dry weight from the saturated weight, the weig!it o thc fluid in 1!ie sampl. . was detemsined. This value was divided by the density of the brine, giving the pore vo!iime nf the samp1e. Porosity was ca!. culated by dividing the pore volume... s to previon. . . d!c &. ; ?c-3 . ud ' The problc. , ras resolved by laboratory measure?? nts on core 0 sa&sp1 as at temperatures ranging Crom 72 F to 368 I' and miih brine resistiv&ties fr. mi 5 ohm-cm to 20 ohm-cm. Enperimcnta1. results indicated that te...

Brannan, Geryl Owen

1972-01-01

402

Stress, temperature, heart rate, and hibernating factors in hamsters. [pathophysiological conditions resulting from exposure to zero gravity  

NASA Technical Reports Server (NTRS)

Pathophysiological conditions resulting from prolonged exposure to zero gravity, cabin constraint, altered ambient environment, whether it be noise, vibrations, high temperatures, or combinations of such factors, are studied in laboratory animals and applied to manned space flight. Results and plans for further study are presented. Specific topics covered include: thermoregulation and its role in reflecting stress and adaptation to the gravity free environment and cabin confinement with its altered circadian forcings; renal function and its measurement in electrolyte distribution and blood flow dynamics; gastronintestinal function and an assessment of altered absorptive capacity in the intestinal mucosa; and catecholamine metabolism in terms of distribution and turnover rates in specific tissues.

Musacchia, X. J.

1974-01-01

403

Mechanical Q-factor Measurement of a Quartz Oscillator at Cryogenic Temperature  

NASA Astrophysics Data System (ADS)

By cooling a small macroscopic object with high mechanical quality, we can realize an “ideal” harmonic oscillator that has quite low intrinsic dissipation, showing extremely small thermal noise. Although a micromechanical system rarely has a high Q-factor, we have succeeded to observe Q˜5×106, using a tuning-fork-type quartz-crystal resonator of sub-mg scale; this value is quite high compared with that of other systems. Regarding such a mechanical oscillator, we discuss the quantum behavior of a macromechanical system coupled to laser light.

Mori, Takumi; Moriwaki, Shigenori; Mio, Norikatsu

2008-07-01

404

Aureolegraph internal scattering correction.  

PubMed

Two methods of determining instrumental scattering for correcting aureolegraph measurements of particulate solar scattering are presented. One involves subtracting measurements made with and without an external occluding ball and the other is a modification of the Langley Plot method and involves extrapolating aureolegraph measurements collected through a large range of solar zenith angles. Examples of internal scattering correction determinations using the latter method show similar power-law dependencies on scattering, but vary by roughly a factor of 8 and suggest that changing aerosol conditions during the determinations render this method problematic. Examples of corrections of scattering profiles using the former method are presented for a range of atmospheric particulate layers from aerosols to cumulus and cirrus clouds. PMID:23207299

DeVore, John; Villanucci, Dennis; LePage, Andrew

2012-11-20

405

[Temperature as a factor of development of psychrotolerant mycelial bacteria complexes in soils of north regions].  

PubMed

It has been demonstrated that complexes of mycelial bacteria (actinomycetes), in which the amount of psychrotolerant actinomycetes reaches hundreds of thousands of CFU/g of the soil (frequently exceeding the portion of mesophilic forms), are developed in peat and podzolic soils of the tundra and taiga at low temperatures. As actinomycetes grow and develop in cold soils, their mycelium increases in length. Use of the molecular in situ hybridization method (fluorescent in situ hybridization, FISH) demonstrated that the portion of metabolically active mycelial actinobacteria exceeds the portion of unicellular actinobacteria in the Actinobacteria phylum. Specific peculiarities of psychrotolerant populations in relation to the spectrum of consumed substrates (histidine, mannitol, saccharose) were established by the method of multirespirometric testing. PMID:23136737

Zenova, G M; Kozhevin, P A; Manucharova, N A; Dubrova, M S; Zviagintsev, D G

2012-01-01

406

Study of Inactivation Factors in Low Temperature Surface-wave Plasma Sterilization  

NASA Astrophysics Data System (ADS)

In this study we investigated the low temperature surface-wave plasma sterilization of directly and indirectly exposed Geobacillus stearothermophilus spores with a large-volume microwave plasma device. The air-simulated gas mixture was used to produce the plasma. The water vapor addition to the gas mixture improved the sterilization efficiency significantly. The effect of ultraviolet photons produced along with plasma to inactivate the spores was studied using a separate chamber, which was evacuated to less than one mTorr and was observed that spores were sterilized within 60 min. The scanning electron microscopy images revealed no significant changes in the actual size of the spores with that of untreated spores despite the survival curve shown that the spores were inactivated.

Singh, Mrityunjai Kumar; Xu, Lei; Ogino, Akihisa; Nagatsu, Masaaki

407

Role of electronic correlation in high-low temperature phase transition of hexagonal nickel sulfide: a comparative density functional theory study with and without correction for on-site Coulomb interaction.  

PubMed

The structural, electronic, magnetic, and elastic properties of hexagonal nickel sulfide (NiS) have been investigated comparatively by Density Functional theory (DFT) and DFT plus correction for on-site Coulomb interaction (DFT+U), in which two different exchange correlation functionals local density approximations (LDA) and general gradient approximations (GGA) in the form of Perdew-Burke-Ernzerhof (PBE) are used. Our results indicate LDA and PBE methods predict hexagonal NiS to be a paramagnetic metal whereas LDA(PBE)+U calculations with reasonable on-site Coulomb interaction energy give the antiferromagnetic insulating state of low temperature hexagonal NiS successfully. Meanwhile, compared with LDA(PBE) results, LDA(PBE)+U methods give larger lattice parameters, crystal volume, and shear constant c44, consistent with the experimental picture during high-low temperature phase transition of hexagonal NiS, in which an increase of the shear constant c44 and lattice parameters were found in the low-temperature antiferromagnetic phase. The present DFT and DFT+U calculations provide a reasonable description for the properties of high temperature and low temperature hexagonal NiS respectively, which indicates that electronic correlation is responsible for this high-low temperature phase transition. PMID:23822260

Zhang, Wei-Bing; Li, Jie; Tang, Bi-Yu

2013-06-28

408

Factors regulating soil surface CO2 and NOx flux in response to high temperature, pulse water events, and nutrient fertilization  

NASA Astrophysics Data System (ADS)

Trace gas emissions from the soil surface are often underestimated due to poor understanding of the factors regulating fluxes under extreme conditions when moisture can be highly variable. In particular, dynamics of soil surface trace gas emissions from hot agricultural regions can be difficult to predict due to the sporadic use of flood irrigation and nitrogen fertilization. Soil surface CO2 and NOx fluxes are especially difficult to predict due to nonlinear responses to pulse water and fertilization events. Additionally, models such as Lloyd and Taylor (1994) and Yienger and Levy II (1995) are not well parameterized for soil surface CO2 and NOx flux, respectively, under excessively high temperatures. We measured soil surface CO2 and NOx flux in an agricultural field transitioning from fallow to biofuel crop production (Sorghum bicolor). Soil surface CO2 flux was measured using CO2 probes coupled with the flux-gradient method. NOx measurements were made using chambers coupled with a NOx monitor. Our field site is located at the University of California Desert Research and Extension Center in the Imperial Valley of CA. Air temperatures regularly exceed 42°C in the summer. Flood irrigation is used at the site as well as nitrogen fertilizers. Soil respiration ranged from 0-15 ?moles CO2 m-2 s-1, with strong hysteresis observed both with and without plants. Soil CO2 fluxes measured in the fallow field before the biofuel crop was planted were temperature independent and mainly regulated by soil moisture. When plants were introduced, temperature became an important predictor for soil respiration as well as canopy height. NOx fluxes were highest at intermediate soil moisture and varied significantly across an irrigation cycle. NOx emissions were temperature dependent, ranging from 3-113 ng N cm-2 hr-1. Neither CO2 nor NOx emissions showed inhibition at soil temperatures up to 55°C. Models may underestimate fluxes of CO2 and NOx from hot agricultural regions due to their inability to account for high temperature emission behavior, responses to irrigation and fertilization events, and influence of vegetation on soil surface trace gas flux.

Oikawa, P. Y.; Grantz, D. A.; Chatterjee, A.; Eberwein, J. R.; Allsman, L. A.; Jenerette, D.

2012-12-01

409

Regression analysis in modeling of air surface temperature and factors affecting its value in Peninsular Malaysia  

NASA Astrophysics Data System (ADS)

This study encompasses air surface temperature (AST) modeling in the lower atmosphere. Data of four atmosphere pollutant gases (CO, O3, CH4, and H2O) dataset, retrieved from the National Aeronautics and Space Administration Atmospheric Infrared Sounder (AIRS), from 2003 to 2008 was employed to develop a model to predict AST value in the Malaysian peninsula using the multiple regression method. For the entire period, the pollutants were highly correlated (R=0.821) with predicted AST. Comparisons among five stations in 2009 showed close agreement between the predicted AST and the observed AST from AIRS, especially in the southwest monsoon (SWM) season, within 1.3 K, and for in situ data, within 1 to 2 K. The validation results of AST with AST from AIRS showed high correlation coefficient (R=0.845 to 0.918), indicating the model's efficiency and accuracy. Statistical analysis in terms of ? showed that H2O (0.565 to 1.746) tended to contribute significantly to high AST values during the northeast monsoon season. Generally, these results clearly indicate the advantage of using the satellite AIRS data and a correlation analysis study to investigate the impact of atmospheric greenhouse gases on AST over the Malaysian peninsula. A model was developed that is capable of retrieving the Malaysian peninsulan AST in all weather conditions, with total uncertainties ranging between 1 and 2 K.

Rajab, Jasim Mohammed; Jafri, Mohd. Zubir Mat; Lim, Hwee San; Abdullah, Khiruddin

2012-10-01

410

Exercise hyperthermia as a factor limiting physical performance - Temperature effect on muscle metabolism  

NASA Technical Reports Server (NTRS)

The effect of trunk cooling on the muscle contents of ATP, ADP, AMP, creatine phosphate (CrP), and creatine, as well as of glycogen, some glycolytic intermediates, pyruvate, and lactate were assessed in 11 fasted dogs exercised at 20 C on treadmill to exhaustion. Without cooling, dogs were able to run 57 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 and 43.0 C, respectively. Cooling with ice packs prolonged the ability to run by 45 percent, and resulted in lower Tre (by 1.1 C) and Tm (by 1.2 C). Depletion of muscle content of total high-energy phosphates (ATP + CrP) and glycogen, and increases in contents of AMP, pyruvate, and lactate were lower in cooled dogs than in non-cooled dogs. The muscle content of lactiate correlated positively with TM. These results indicate that hypothermia accelerates glycolysis, and shifts the equilibrium between high- and low-energy phosphates in favor of the latter. The adverse effect of hypothermia on muscle metabolism may be relevant to the limitation of endurance.

Kozlowski, S.; Brzezinska, Z.; Kruk, B.; Kaciuba-Uscilko, H.; Greenleaf, J. E.

1985-01-01

411

A Study of Reflectance Spectra of Deciduous Tree Leaves with an attempt to Correlate Environmental Factors of Temperature and Precipitation  

NASA Astrophysics Data System (ADS)

Students at the Model Secondary School for the Deaf are investigating if there is any variation in leaf reflectance spectra that correlates with environmental factors. Past student investigations have indicated differences in the reflectance spectra of fresh, aged and dead leaves (MSSD student ESS investigations 2000 and 2001). Would there be a change in leaf reflectance spectra in response to temperature or moisture variations? The students hypothesized that the leaves may respond to precipitation differences (or drought) but probably will not respond spectrally to the temperature range normally encountered during the spring time in Washington, D.C.. The ALTA spectrometer will be used to detect the reflectance spectra of living tree leaves at regular intervals during the spring. Daily temperature and precipitation data will be collected at the school GLOBE (Global Learning and Observations to Benefit the Environment) Atmosphere Study Site. The students became interested in this question through questions about how much could be determined from satellite measurements about the relative health of forest vegetation.

Ellsworth, M. S.; Dowling, A.; Johnson, R.; Lewis, C.

2002-05-01

412

Factors affecting the wettability of different surface materials with vegetable oil at high temperatures and its relation to cleanability  

NASA Astrophysics Data System (ADS)

The main aim of the work was to investigate the wettability of different surface materials with vegetable oil (olive oil) over the temperature range of 25-200 °C to understand the differences in cleanability of different surfaces exposed to high temperatures in food processes. The different surface materials investigated include stainless steel (reference), PTFE (polytetrafluoroethylene), silicone, quasicrystalline (Al, Fe, Cr) and ceramic coatings: zirconium oxide (ZrO2), zirconium nitride (ZrN) and titanium aluminum nitride (TiAlN). The ceramic coatings were deposited on stainless steel with two different levels of roughness. The cosine of the contact angle of olive oil on different surface materials rises linearly with increasing temperature. Among the materials analyzed, polymers (PTFE, silicone) gave the lowest cos ? values. Studies of the effect of roughness and surface flaws on wettability revealed that the cos ? values increases with increasing roughness and surface flaws. Correlation analysis indicates that the measured contact angle values gave useful information for grouping easy-clean polymer materials from the other materials; for the latter group, there is no direct relation between contact angle and cleanability. In addition to surface wettability with oil many other factors such as roughness and surface defects play an essential role in determining their cleanability.

Ashokkumar, Saranya; Adler-Nissen, Jens; Møller, Per

2012-12-01

413