WorldWideScience
1

Comparisons of Air Radiation Model with Shock Tube Measurements  

Science.gov (United States)

This paper presents an assessment of the predictive capability of shock layer radiation model appropriate for NASA s Orion Crew Exploration Vehicle lunar return entry. A detailed set of spectrally resolved radiation intensity comparisons are made with recently conducted tests in the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. The spectral range spanned from vacuum ultraviolet wavelength of 115 nm to infrared wavelength of 1400 nm. The analysis is done for 9.5-10.5 km/s shock passing through room temperature synthetic air at 0.2, 0.3 and 0.7 Torr. The comparisons between model and measurements show discrepancies in the level of background continuum radiation and intensities of atomic lines. Impurities in the EAST facility in the form of carbon bearing species are also modeled to estimate the level of contaminants and their impact on the comparisons. The discrepancies, although large is some cases, exhibit order and consistency. A set of tests and analyses improvements are proposed as forward work plan in order to confirm or reject various proposed reasons for the observed discrepancies.

Bose, Deepak; McCorkle, Evan; Bogdanoff, David W.; Allen, Gary A., Jr.

2009-01-01

2

Modelling geo-magnetic radiation from extensive air showers  

Energy Technology Data Exchange (ETDEWEB)

An incoming ultra high energy cosmic ray (UHECR) entering our atmosphere will create a so called extensive air shower (EAS). A cascade of particles flying toward the Earth's surface with extremely high velocities. As a result of this they are concentrated in a thin shower front, which can be visualized by a pancake of particles flying toward the Earth. The deflection of electrons and positrons due to the Earth magnetic field in combination with retardation effects is responsible for an electromagnetic pulse to be emitted within the radio frequency range. Concentrating on a macroscopic description, focussing on the net current created due to the deflection of the electrons and positrons in the Earth magnetic field, a model has been made to simulate the radio signal for a realistic air shower. Several different contributions to the electric pulse have been included to obtain more realistic simulations and have a better comparison with measured data.

Vries, Krijn de; Scholten, Olaf [KVI, University of Groningen (Netherlands); Werner, Klaus [Subatech, Universaty of Nantes (France)

2009-07-01

3

Modelling geo-magnetic radiation from extensive air showers  

International Nuclear Information System (INIS)

An incoming ultra high energy cosmic ray (UHECR) entering our atmosphere will create a so called extensive air shower (EAS). A cascade of particles flying toward the Earth's surface with extremely high velocities. As a result of this they are concentrated in a thin shower front, which can be visualized by a pancake of particles flying toward the Earth. The deflection of electrons and positrons due to the Earth magnetic field in combination with retardation effects is responsible for an electromagnetic pulse to be emitted within the radio frequency range. Concentrating on a macroscopic description, focussing on the net current created due to the deflection of the electrons and positrons in the Earth magnetic field, a model has been made to simulate the radio signal for a realistic air shower. Several different contributions to the electric pulse have been included to obtain more realistic simulations and have a better comparison with measured data.

4

A model for combined radiation temperature accelerated aging of PVC and polyethylene in air  

International Nuclear Information System (INIS)

In order to extrapolate material accelerated aging data, models must be developed based on sufficient understanding of the processes leading to material degradation. A model is proposed to explain the extremely complex degradation behaviors of PVC and polyethylene materials in combined radiation/temperature/air aging environments. The model is based on simple chemical kinetic assumptions. Using a time, temperature, radiation dose rate shift procedure, we will show that accelerated aging data for the PVC and polyethylene materials are consistent with the model and that model extrapolation are in excellent agreement with 12-year real-time aging results from actual nuclear plant electrical cable. 4 figs.

5

Experimental study and improved modeling of high-temperature air radiation  

International Nuclear Information System (INIS)

Spectral emission measurements were conducted in an atmospheric pressure air plasma. The thermodynamic state of the plasma was determined to be close to local thermodynamic equilibrium (LTE), and the temperature profile was measured. The spectrum emitted by the plasma over the range 2,000 to 8,000 A was recorded and calibrated. This spectrum comprises the major radiating molecular bands and atomic lines in air, and is therefore proposed as a benchmark to test radiative calculations. A comparison of these results with the predictions of the NEQAIR code induced several modeling improvements in the code. In particular, radiative transition probabilities and spectroscopic constants were updated, and additional band systems of NO (NO Delta, Epsilon, Beta prime and Gamma prime) were included. Since the C state from which the NO Delta transition originates is predissociated, a simplified collision-predissociation model for this state was added to the code. These changes are presented, and their effect discussed. 34 refs

6

Experimental study and improved modeling of high-temperature air radiation  

Science.gov (United States)

Spectral emission measurements were conducted in an atmospheric pressure air plasma. The thermodynamic state of the plasma was determined to be close to local thermodynamic equilibrium (LTE), and the temperature profile was measured. The spectrum emitted by the plasma over the range 2,000 to 8,000 A was recorded and calibrated. This spectrum comprises the major radiating molecular bands and atomic lines in air, and is therefore proposed as a benchmark to test radiative calculations. A comparison of these results with the predictions of the NEQAIR code induced several modeling improvements in the code. In particular, radiative transition probabilities and spectroscopic constants were updated, and additional band systems of NO (NO Delta, Epsilon, Beta prime and Gamma prime) were included. Since the C state from which the NO Delta transition originates is predissociated, a simplified collision-predissociation model for this state was added to the code. These changes are presented, and their effect discussed.

Laux, Christophe O.; Moreau, Stephane; Kruger, Charles H.

1992-07-01

7

Experimental study and improved modeling of high-temperature air radiation  

Energy Technology Data Exchange (ETDEWEB)

Spectral emission measurements were conducted in an atmospheric pressure air plasma. The thermodynamic state of the plasma was determined to be close to local thermodynamic equilibrium (LTE), and the temperature profile was measured. The spectrum emitted by the plasma over the range 2,000 to 8,000 A was recorded and calibrated. This spectrum comprises the major radiating molecular bands and atomic lines in air, and is therefore proposed as a benchmark to test radiative calculations. A comparison of these results with the predictions of the NEQAIR code induced several modeling improvements in the code. In particular, radiative transition probabilities and spectroscopic constants were updated, and additional band systems of NO (NO Delta, Epsilon, Beta prime and Gamma prime) were included. Since the C state from which the NO Delta transition originates is predissociated, a simplified collision-predissociation model for this state was added to the code. These changes are presented, and their effect discussed. 34 refs.

Laux, C.O.; Moreau, S.; Kruger, C.H. (Stanford University, CA (United States))

1992-07-01

8

Models for obtaining daily global solar radiation with measured air temperature data in Madrid (Spain)  

International Nuclear Information System (INIS)

Solar radiation is a primary driver for many physical, chemical and biological processes on the earth's surface. Complete and accurate solar radiation data at a specific region are quite indispensable to the solar energy related research. For locations where measured values are not available, a number of formulas and models have been developed to estimate solar radiation. This study aimed to calibrate seven existing models and develop one new model for estimating global solar radiation data using temperature measured data for seven stations located in Madrid, Spain. This work concludes that empirical models based on temperature give good results in any location if the parameters are correctly adjusted. A newly developed model that include the difference between maximum and minimum daily air temperature, and the saturation vapour pressures at temperature maximum and minimum, provided estimates with less error than other models. According to the results, the new model showed the best estimation for all stations and therefore is recommended. It is believed that the model developed in this work is applicable for estimating the daily global solar radiation on a horizontal surface at any site in Community of Madrid, Spain. The daily global solar radiation values produced by this approach can be used in the design and estimation of the performance of solar applications.

9

A new dynamical atmospheric ionizing radiation (AIR) model for epidemiological studies  

Science.gov (United States)

A new Atmospheric Ionizing Radiation (AIR) model is currently being developed for use in radiation dose evaluation in epidemiological studies targeted to atmospheric flight personnel such as civilian airlines crewmembers. The model will allow computing values for biologically relevant parameters, e.g. dose equivalent and effective dose, for individual flights from 1945. Each flight is described by its actual three dimensional flight profile, i.e. geographic coordinates and altitudes varying with time. Solar modulated primary particles are filtered with a new analytical fully angular dependent geomagnetic cut off rigidity model, as a function of latitude, longitude, arrival direction, altitude and time. The particle transport results have been obtained with a technique based on the three-dimensional Monte Carlo transport code FLUKA, with a special procedure to deal with HZE particles. Particle fluxes are transformed into dose-related quantities and then integrated all along the flight path to obtain the overall flight dose. Preliminary validations of the particle transport technique using data from the AIR Project ER-2 flight campaign of measurements are encouraging. Future efforts will deal with modeling of the effects of the aircraft structure as well as inclusion of solar particle events. Published by Elsevier Ltd on behalf of COSPAR.

De Angelis, G.; Clem, J. M.; Goldhagen, P. E.; Wilson, J. W.

2003-01-01

10

An improved mathematical model for prediction of air quantity to minimise radiation levels in underground uranium mines.  

Science.gov (United States)

Ventilation is the primary means of controlling radon and its daughter concentrations in an underground uranium mine environment. Therefore, prediction of air quantity is the vital component for planning and designing of ventilation systems to minimise the radiation exposure of miners in underground uranium mines. This paper comprehensively describes the derivation and verification of an improved mathematical model for prediction of air quantity, based on the growth of radon daughters in terms of potential alpha energy concentration (PAEC), to reduce the radiation levels in uranium mines. The model also explains the prediction of air quantity depending upon the quality of intake air to the stopes. This model can be used to evaluate the contribution of different sources to radon concentration in mine atmosphere based on the measurements of radon emanation and exhalation. Moreover, a mathematical relationship has been established for quick prediction of air quantity to achieve the desired radon daughter concentration in the mines. PMID:25461521

Panigrahi, Durga Charan; Sahu, Patitapaban; Mishra, Devi Prasad

2015-02-01

11

Numerical Modelling of Air Streamer Discharge Radiation in the Second Positive and First Negative Systems of Molecular Nitrogen  

International Nuclear Information System (INIS)

Numerical modelling of radiation pulses of an air streamer discharge in the second positive and first negative systems of molecular nitrogen is performed, accounting for non-stationary processes of population and depopulation of the excited states. Temporal characteristics of radiation pulses are obtained in dependence upon a streamer intensity and spatial resolution of a spectral optical system. It is shown that spectral diagnostic methods based on steady state approximations are inapplicable to non-stationary and non-equilibrium streamer plasma. (author)

12

Modeling the UV and VUV radiative emission of high-temperature air  

Science.gov (United States)

A study of the radiative emission of high-temperature air in the spectral range 800-4000 A (ultraviolet and vacuum ultraviolet) is presented. This spectral range is important for several reasons. First, a significant, if not dominant, amount of radiative power is emitted at these wavelengths because at high temperature, high-lying excited electronic levels are significantly populated, and resulting transitions to the ground state produce radiation of high energy and short wavelength. Second, the spectral features due to these high-lying electronic levels can be used to determine vibrational, rotational and electronic temperatures which can help validate flowfield solutions. The NEQAIR code is modified to include a revised treatment of NO delta and NO epsilon which are shown to be the major radiators in the range 1600-2500 A. Estimates are provided of the importance of two electronic systems (N2 Birge-Hopfield I and Carroll-Yoshino) that were not considered in NEQAIR previously. The influence of absorption by the O2 Schumann-Runge dissociation continuum is also examined.

Laux, Christophe O.; Gessman, Richard J.; Kruger, Charles H.

1993-07-01

13

Developing, Coupling, and Applying a Gas, Aerosol, Transport, and Radiation Model to Study Urban and Regional Air Pollution.  

Science.gov (United States)

This thesis discusses the development of a gas, aerosol, transport, and radiation air quality model (GATOR), the coupling of GATOR to a mesoscale meteorological and tracer dispersion model (MMTD), and the application of the resulting GATOR/MMTD air pollution modeling system (APMS) to studies of gas and aerosol pollution buildup in the Los Angeles Basin. GATOR consists of computer algorithms that simulate four groups of atmospheric processes: gas, aerosol, transport, and radiation processes. Gas processes include chemistry, emissions, gas-to-particle conversion, optical depth attenuation, and deposition. Aerosol processes include size-resolved emissions, nucleation, coagulation, condensational growth, dissolutional growth, evaporation, chemical equilibrium, aqueous chemistry, optical depth attenuation, deposition, and sedimentation. Transport processes include horizontal advection and diffusion and vertical diffusion of all gases and particles, and they require meteorological data as inputs. To drive the transport processes, the MMTD, developed by R. Lu and R. P. Turco, was coupled to GATOR. The MMTD predicts wind speed, wind direction, temperature, humidity, and pressure, among other variables. Finally, radiation processes in GATOR include spectrally-resolved scattering and absorption by gases, aerosols, fogs, and clouds, and calculation of mean intensities and heating rates. I used the GATOR/MMTD modeling system to predict pollution buildup in Los Angeles during the Southern California Air Quality Study (SCAQS) period of August 26-28, 1987. Among the model inputs were emissions, soil moisture, albedo, topographical, landuse, and chemical rate data. To validate the model, surface observations were compared to model predictions of gas-phase ozone, nitric oxide, nitrogen dioxide, carbon monoxide, sulfur dioxide, methane, total non-methane hydrocarbons, formaldehyde, peroxyacetylnitrate, hydrogen peroxide, nitric acid, nitrous acid, and ammonia concentrations. Observations were also compared to predictions of aerosol-phase ammonium, nitrate, sodium, chloride, sulfate, and total particulate concentrations. Finally, observations were compared to predictions of solar radiation and scattering coefficients. In sum, the GATOR/MMTD system predicted ozone to within a normalized gross error of 20 -35% during the study period. Additional statistics and time-series plots are shown.

Jacobson, Mark Zachary

14

Method for Water Vapor Profile Retievals by Means of Minimizing Difference Between Estimated and Actual Brightness Temperatures Derived from AIRS data and Radiative Transfer Model  

OpenAIRE

Method for water vapor profile retrievals by means of minimizing difference between estimated and actual brightness temperatures derived from AIRS data and radiative transfer model is proposed. Initial value is determined by linearized radiative transfer equation. It is found that this initial value determination method makes improvement of estimation accuracy together with reducing convergence time

Kohei Arai

2013-01-01

15

Radiation protection of air crew at exposition with cosmic radiation  

International Nuclear Information System (INIS)

In this presentation authors deals with radiation protection of air crew at exposition by cosmic radiation. Some results of measurements of dose equivalents on some air board from Slovakia are presented

16

Infrared Signature Masking by Air Plasma Radiation  

Science.gov (United States)

This report summarizes the results obtained during a research program on the infrared radiation of air plasmas conducted in the High Temperature Gasdynamics Laboratory at Stanford University under the direction of Professor Charles H. Kruger, with Dr. Christophe O. Laux as Associate Investigator. The goal of this research was to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. To this end, spectral measurements and modeling were made of the radiation emitted between 2.4 and 5.5 micrometers by an atmospheric pressure air plasma in chemical and thermal equilibrium at a temperature of approximately 3000 K. The objective was to examine the spectral emission of air species including nitric oxide, atomic oxygen and nitrogen lines, molecular and atomic continua, as well as secondary species such as water vapor or carbon dioxide. The cold air stream injected in the plasma torch contained approximately 330 parts per million of CO2, which is the natural CO2 concentration in atmospheric air at room temperatures, and a small amount of water vapor with an estimated mole fraction of 3.8x10(exp -4).

Kruger, Charles H.; Laux, C. O.

2001-01-01

17

Infrared Signature Masking by Air Plasma Radiation  

Science.gov (United States)

Detailed measurements and modeling of the spectral emission of an atmospheric pressure air plasma at temperatures up to -3400 K have been made. The cold gas injected in the plasma torch contained an estimated mole fraction of water vapor of approximately 4.5 x 10(exp -3) and an estimated carbon dioxide mole fraction of approximately 3.3 x 10(exp -4). Under these conditions, the minimum level of air plasma emission is found to be between 3.9 and 4.15 microns. Outside this narrow region, significant spectral emission is detected that can be attributed to the fundamental and overtone bands of NO and OH, and to the v(sub 3) and the (v(sub 1)+v(sub 3)) bands Of CO2. Special attention was paid to the effects of ambient air absorption in the optical path between the plasma and the detector. Excellent quantitative agreement is obtained between the measured and simulated spectra, which are both on absolute intensity scales, thus lending confidence in the radiation models incorporated into NEQAIR2-IR over the course of this research program.

Kruger, C. H.; Laux, C. O.

1998-01-01

18

Modeling air travel behavior  

OpenAIRE

Modeling passengers’ flight choice behavior is valuable to understanding the increasingly competitive airline market and predicting air travel demands. This report estimates standard and mixed multinomial logit models of itinerary choice for business travel, based on a stated preference survey conducted in 2001. Previous work on air travel behavior modeling hasalmost exclusively been confined to studying either airport or airline choice. However, two recent papers have expanded th...

Warburg, Valdemar; Nielsen, Otto Anker; Bhat, Chandra

2006-01-01

19

Nonequilibrium air radiation (Nequair) program: User's manual  

Science.gov (United States)

A supplement to the data relating to the calculation of nonequilibrium radiation in flight regimes of aeroassisted orbital transfer vehicles contains the listings of the computer code NEQAIR (Nonequilibrium Air Radiation), its primary input data, and explanation of the user-supplied input variables. The user-supplied input variables are the thermodynamic variables of air at a given point, i.e., number densities of various chemical species, translational temperatures of heavy particles and electrons, and vibrational temperature. These thermodynamic variables do not necessarily have to be in thermodynamic equilibrium. The code calculates emission and absorption characteristics of air under these given conditions.

Park, C.

1985-07-01

20

Cosmic radiation and air crew exposure  

International Nuclear Information System (INIS)

When the primary particles from space, mainly protons, enter the atmosphere, they interact with the air nuclei and induce cosmic-ray shower. When an aircraft is in the air, the radiation field within includes many types of radiation of large energy range; the field comprises mainly photons, electrons, positrons and neutrons. Cosmic radiation dose for crews of air crafts A 320 and ATR 42 was measured using TLD-100 (LiF: Mg, Ti) detectors and the Mini 6100 semiconductor dosimeter; radon concentration in the atmosphere was measured using the Alpha Guard radon detector. The total annual dose estimated for the A 320 aircraft crew, at altitudes up to 12000 meters, was 5.3 mSv (including natural radon radiation dose of 1.1 mSv).(author)

21

Greenhouse air temperature modelling  

OpenAIRE

This paper describes two implementation approaches for modelling the air temperature of an automated greenhouse located in the campus of the University of Trás-os- Montes e Alto Douro. Linear models, based in the discretization of the heat transfer physical laws, and non-linear neural networks models are used. These models are describes as functions of the outside climate and control actions performed for heating and cooling. Results are presented to illustrate the performance of each model ...

Cunha, Jose? Boaventura; Oliveira, Paulo; Coelho, J. P.

2004-01-01

22

World-wide radiation dosage calculations for air crew members  

Science.gov (United States)

A greatly improved version of the computer program to calculate radiation dosage to air crew members is now available. Designated CARI-6, this program incorporates an updated geomagnetic cutoff rigidity model and a revision of the primary cosmic ray spectrum based on recent work by Gaisser and Stanev (1998). We believe CARI-6 provides the most accurate available method for calculating the radiation dosage to air crew members. The program is now utilized by airline companies around the world and provides unification for subsequent world-wide studies on the effects of natural radiation on aircrew members.

O'Brien, K.; Smart, D. F.; Shea, M. A.; Felsberger, E.; Schrewe, U.; Friedberg, W.; Copeland, K.

23

Subsonic radiation waves in air  

International Nuclear Information System (INIS)

It is shown that fast waves of absorption of laser radiation with the propagation mechanism dominated by the role of the intrinsic radiation emitted from the resultant plasma may appear at flux densities at least an order of magnitude lower than those at which they have been observed experimentally. An expanding plasma generates a shock wave where the pressure is much higher than atmospheric. Numerical calculations relating to the spectral radiation-dynamic problem are used to study the evolution of such subsonic radiation waves traveling from the initial plasma layer and to determine the time dependences of their main parameters (up to the quasisteady propagation stage). It is shown that these effects may occur when the flux (power) density exceeds 0.1 MW/cm2 for CO2 lasers and 1 MW/cm2 for neodymium lasers

24

SESAM: a model for the calculation of radiation exposure by emission of pollutants with the exhaust air in the case of a multi-source situation  

International Nuclear Information System (INIS)

The report deals with the calculation of the individual radiation exposure in the catchment area of several nuclear emitters. A model and computer program, SESAM - Calculation of the Radiation Exposure by Emission of Pollutants with the Exhaust air in the Case of a Multi-Source Situation -, was developed which makes possible all the evaluations of long-time exposure which are relevant for the licensing process - such as the determination of the maximum individual radiation exposure to the various organs at the worst receiving point - together with the exposure of the environment by several nuclear emission sources - such as, for example, several units of a power plant facility, the various emitters of a waste management center, or even consideration of the previous exposure of a site by nuclear emission sources

25

40 CFR 1.41 - Office of Air and Radiation.  

Science.gov (United States)

...functions of the Office of Air and Radiation. The Director for Air Quality Planning and Standards...programs, technical policies, regulations, guidelines...and criteria for air pollution control...success in achieving air quality goals; for...

2010-07-01

26

Extension of radiative transfer code MOMO, matrix-operator model to the thermal infrared - Clear air validation by comparison to RTTOV and application to CALIPSO-IIR  

Science.gov (United States)

1-D radiative transfer code Matrix-Operator Model (MOMO), has been extended from [0.2-3.65 ?m] the band to the whole [0.2-100 ?m] spectrum. MOMO can now be used for the computation of a full range of radiation budgets (shortwave and longwave). This extension to the longwave part of the electromagnetic radiation required to consider radiative transfer processes that are features of the thermal infrared: the spectroscopy of the water vapor self- and foreign-continuum of absorption at 12 ?m and the emission of radiation by gases, aerosol, clouds and surface. MOMO's spectroscopy module, Coefficient of Gas Absorption (CGASA), has been developed for computation of gas extinction coefficients, considering continua and spectral line absorptions. The spectral dependences of gas emission/absorption coefficients and of Planck's function are treated using a k-distribution. The emission of radiation is implemented in the adding-doubling process of the matrix operator method using Schwarzschild's approach in the radiative transfer equation (a pure absorbing/emitting medium, namely without scattering). Within the layer, the Planck-function is assumed to have an exponential dependence on the optical-depth. In this paper, validation tests are presented for clear air case studies: comparisons to the analytical solution of a monochromatic Schwarzschild's case without scattering show an error of less than 0.07% for a realistic atmosphere with an optical depth and a blackbody temperature that decrease linearly with altitude. Comparisons to radiative transfer code RTTOV are presented for simulations of top of atmosphere brightness temperature for channels of the space-borne instrument MODIS. Results show an agreement varying from 0.1 K to less than 1 K depending on the channel. Finally MOMO results are compared to CALIPSO Infrared Imager Radiometer (IIR) measurements for clear air cases. A good agreement was found between computed and observed radiance: biases are smaller than 0.5 K and Root Mean Square Error (RMSE) varies between 0.4 K and 0.6 K depending on the channel. The extension of the code allows the utilization of MOMO as forward model for remote sensing algorithms in the full range spectrum. Another application is full range radiation budget computations (heating rates or forcings).

Doppler, Lionel; Carbajal-Henken, Cintia; Pelon, Jacques; Ravetta, François; Fischer, Jürgen

2014-09-01

27

Co-60 radiation in air  

International Nuclear Information System (INIS)

One of the responsibilities of the Staatliche Materialpruefungsamt NW (materials testing office) is to run an official personal dosimetry service in the Federal Republic. Approximately 80.000 films, 2000 thermoluminescent (TLD) ring dosemeters and 2000 glass dosemeters are evaluated every month as a part of the official monitoring of doses received by individuals. The service also carries out voluntary monitoring of whole body doses with TLD's and evaluates TLD's for the environmental monitoring of nuclear installations and for other area monitoring purposes. In addition TLD's are evaluated in order to check doses received during medical irradiation programmes and as part of tests on working materials. At the site occupied by the testing office, the Dortmund Weights and Measures Department operates its installations for the calibration of dose and dose-rate meters for photon radiation. The available isotope sources comprise Cs-137 up to 3.7.103 Bq and Co-60 up to 1.85·1013 Bq. If high dose rates are required to produce high doses within a short period when simulating suspected accidents, these installations are also used by the dosimetry service. For the purposes of routine calibration and the production of blind samples, which are introduced in the routine evaluation without the knowledge of the assistants to ensure that the evaluation results are accurate, the dosimetry service runs its own irradiation facilitiesfacilities

28

Radiation control at open-air sediment fixation facility  

International Nuclear Information System (INIS)

For disposal of radioactive wastes at NPP A-1 it was necessary to built special facilities for their treatment. One of them is a facility for sediment fixation by its cementation that was designed and constructed by VUJE a.s. in 2004 -2005. A 3D model of this facility is shown. Except of technological parts of the facility , the system of radiation control plays an important role, too. Range of the radiation control system fulfils demands of the valid legislative documents, the technical design of the technology sediment fixation and the present state of objects VYZ Jaslovske Bohunice. The radiation control system has been designed for monitoring of radiological situation during normal operation as well as during radiation accidents. System of radiation control at fixation facility covers: (1) personnel radiation control; (2) radiation control of working area (semi servicing areas); (3) radiation control of gaseous releases; (4) radiation control of the facility technology, monitoring of the vicinity of the open-air facility; (5) informational system of radiation control. (authors)

29

One-dimensional hydro-kinetic modelling of the decaying arc in air-PA66-copper mixtures: I. Chemical kinetics, thermodynamics, transport and radiative properties  

Energy Technology Data Exchange (ETDEWEB)

A one-dimensional hydro-kinetic model is developed to study arc extinction in a low-voltage breaking device. In part 1 of this double paper, the data necessary for the implementation of the hydro-kinetic model are presented. The equilibrium composition of the plasma is derived from the law of mass action. Mixtures of air and materials ablated from the thermoplastic wall (PA66, monomer C{sub 12}H{sub 22}O{sub 2}N{sub 2}) and from the contacts (copper) are considered. Thermodynamic properties such as mass density, enthalpy and specific heat at constant pressure are then calculated. Transport coefficients (viscosity, electrical conductivity and thermal conductivity) are determined with the Chapman-Enskog theory. Concerning radiation, the net emission coefficient, corresponding to the power radiated per unit volume and per unit solid angle, is calculated. Finally, for chemical kinetics, a reliable set of reaction rate coefficients linking the chemical species of the plasma is compiled. Particular attention is paid to ionization and recombination of atomic species which are obtained with the 'bottleneck' method.

Teulet, Ph; Gonzalez, J J; Mercado-Cabrera, A; Cressault, Y; Gleizes, A, E-mail: philippe.teulet@laplace.univ-tlse.f [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France)

2009-09-07

30

Assessing the Usefulness of AIRS Radiance Observations in a 4D-Var Assimilation Scheme Using the Penn State/NCAR Mesoscale Model Version 5 (MM5) and a Stand Alone Radiative Transfer Algorithm (SARTA)  

Science.gov (United States)

Short-term precipitation forecast skill remains poor despite further advances in numerical modeling and data analysis. Utilizing indirect observations, such as the radiance observations obtained from the Atmospheric Infrared Sounder (AIRS), in a 4D-Var assimilation scheme may lead to a rapid improvement in the skill of 12-h QPF. In order to investigate the usefulness of AIRS observations, the adjoint code of a radiative transfer model (SARTA) is developed and linked to MM5 4D-Var system. A statistical comparison of the AIRS radiances with those calculated using the linked MMS-SARTA model is carried out to assess errors in the radiative transfer model, MM5 and AIRS data, and to develop a quality control scheme. Outliers and any bias that may exist in radiative transfer model, MM5 and AIRS data are identified. An adjoint sensitivity study, utilizing the SARTA adjoint model, is then done to identify the relative sensitivities of each spectral channel to such parameters as atmospheric temperature, pressure, and mixing ratio. Another sensitivity study is done using the MM5 alone to determine the sensitivity of the 12-h QPF to model parameters such as atmospheric temperature, pressure, and mixing ratio under various weather regimes (i.e. summertime convection, winter snowfall). Results from these two types of adjoint sensitivity studies are used to determine which AIRS channels contribute most to 12-h QPF under differing weather regimes. This information is useful when conducting 4D-Var experiments using a subset of the 2378 AIRS spectral channels. Finally, 4D-Var experiments are done to analyze the impact of the AIRS observations on the quality of the 12-h QPF results. This project falls under the data assimilation general session topic as specified by the conference organizers.

Carrier, M.; Zou, X.; Lapenta, W. M.; Jedlovec, G.

2004-01-01

31

Correction of marine air temperature observations for solar radiation effects  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-12-01

32

Investigation of infra-red and nonequilibrium air radiation  

Science.gov (United States)

This report describes progress on the first year of a research program on the infrared radiation of air plasmas conducted in the High Temperature Gasdynamics Laboratory at Stanford University. This program is intended to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. To this date, the radiative emission of air plasmas in the infrared has been the object of few experimental investigations, and although several infrared systems are already modeled in radiation codes such as NEQAIR, measurements are required to validate numerical predictions and indicate whether all transitions of importance are accounted for. The present program is motivated by the fact that 9 excited states (A, B, C, D, B', F, H, and H') of NO radiate in the infrared, especially between 1 and 1.5 microns where at least 9 transitions involving can be observed. Because these IR transitions are relatively well separated from each other, excited NO states concentrations can be easily measured, thus providing essential information on excited-state chemistry for use in optical diagnostics or in electronic excitation model validation. Developing accurate collisional-radiative models for these excited NO states is of importance as the UV-VUV transitions of NO (beta, gamma, epsilon, beta prime, gamma prime) produce a major, if not dominant, fraction of the radiation emitted by air plasmas. During the first year of the program, research has focused on the spectral range 1.0 to 1.5 microns, as detailed in Section 2 of this report. The measurements, conducted in a 50 kW radio-frequency inductively coupled plasma torch operating on air at atmospheric pressure, extend previous shock tube investigations by Wray to a wider spectral range (1.0 to 1.5 microns vs 0.9 to 1.2 microns) and higher temperatures (7600 K in the plasma torch versus 6700 K in the shock-tube). These higher temperatures in the present experiment have made it possible to observe high-lying excited NO states that were previously undetectable. These measurements are currently being extended up to 5 microns, with particular attention paid to the rovibronic bands of ground state NO, molecular continua, CO transitions, and other systems of importance. Publications and presentations resulting from or related to this work are cited in Section 3, and Section 4 lists the personnel who contributed to this report.

Kruger, Charles H.

1995-02-01

33

INEEL AIR MODELING PROTOCOL ext  

Energy Technology Data Exchange (ETDEWEB)

Various laws stemming from the Clean Air Act of 1970 and the Clean Air Act amendments of 1990 require air emissions modeling. Modeling is used to ensure that air emissions from new projects and from modifications to existing facilities do not exceed certain standards. For radionuclides, any new airborne release must be modeled to show that downwind receptors do not receive exposures exceeding the dose limits and to determine the requirements for emissions monitoring. For criteria and toxic pollutants, emissions usually must first exceed threshold values before modeling of downwind concentrations is required. This document was prepared to provide guidance for performing environmental compliance-driven air modeling of emissions from Idaho National Engineering and Environmental Laboratory facilities. This document assumes that the user has experience in air modeling and dose and risk assessment. It is not intended to be a "cookbook," nor should all recommendations herein be construed as requirements. However, there are certain procedures that are required by law, and these are pointed out. It is also important to understand that air emissions modeling is a constantly evolving process. This document should, therefore, be reviewed periodically and revised as needed. The document is divided into two parts. Part A is the protocol for radiological assessments, and Part B is for nonradiological assessments. This document is an update of and supersedes document INEEL/INT-98-00236, Rev. 0, INEEL Air Modeling Protocol. This updated document incorporates changes in some of the rules, procedures, and air modeling codes that have occurred since the protocol was first published in 1998.

C. S. Staley; M. L. Abbott; P. D. Ritter

2004-12-01

34

Determination of the potential radiation exposure of the population close to the Asse II mine caused by deduction of radioactive substances with the discharge air in the normal operation using the ''Atmospheric Radionuclide-Transport-Model'' (ARTM)  

International Nuclear Information System (INIS)

Between 1967 and 1978 125.787 packages filled with low-level and intermediate-level radioactive waste were emplaced in the mining plant Asse II. Volatile radioactive substances like H-3, C-14 and Rn-222 are released from the emplaced waste. These substances reach the ventilated parts of the mine and are released with the discharge air. The potential radiation exposure of the population caused by deduction of radioactive substances with the discharge air in the normal operation is determined by the ''Atmospheric Radionuclide-Transport-Model'' (ARTM). As result the maximal deductions of volatile radioactive substances with the discharge air in the normal operation of the Asse II mine lead to radiation exposure of the population, which is considerably lower than the permissible values of application rate.

35

Air crews - a new group of radiation workers  

International Nuclear Information System (INIS)

Air crews on commercial flights are not generally regarded as occupationally exposed radiation workers. The studies show that they may receive radiation doses in excess of the ICRP recommended limits for members of the public. An international approach to this problem could be enforced through IATA and other organizations in commercial air traffic. The results of the analysis for air crews of Yugoslav Airlines are used as example. (author)

36

Radiation Physics for Space and High Altitude Air Travel  

Science.gov (United States)

Galactic cosmic rays (GCR) are of extra-solar origin consisting of high-energy hydrogen, helium, and heavy ions. The GCR are modified by physical processes as they traverse through the solar system, spacecraft shielding, atmospheres, and tissues producing copious amounts of secondary radiation including fragmentation products, neutrons, mesons, and muons. We discuss physical models and measurements relevant for estimating biological risks in space and high-altitude air travel. Ambient and internal spacecraft computational models for the International Space Station and a Mars mission are discussed. Risk assessment is traditionally based on linear addition of components. We discuss alternative models that include stochastic treatments of columnar damage by heavy ion tracks and multi-cellular damage following nuclear fragmentation in tissue.

Cucinotta, F. A.; Wilson, J. W.; Goldhagen, P.; Saganti, P.; Shavers, M. R.; McKay, Gordon A. (Technical Monitor)

2000-01-01

37

Air pollution V. Modelling, monitoring and management  

Energy Technology Data Exchange (ETDEWEB)

Papers are presented under the following section headings: air pollution management; turbulence modelling at small and meso scales; wind flow and dispersion modelling; air pollution modelling; air pollution modelling and experiments; data analysis; and observations; urban air pollution; emission inventories; monitoring and laboratory studies; chemistry of air pollution; transport pollution; and health problems. Two papers have been abstracted separately for the IEA Coal Research CD-ROM.

Power, H.; Tirabassi, T.; Brebbia, C.A. [eds.] [Wessex Institute of Technology, Southampton (United Kingdom)

1997-12-31

38

Air pollution radiative forcing from specific emissions sectors at 2030  

Science.gov (United States)

Reduction of short-lived air pollutants can contribute to mitigate global warming in the near-term with ancillary benefits to human health. However, the radiative forcings of short-lived air pollutants depend on the location and source type of the precursor emissions. We apply the Goddard Institute for Space Studies atmospheric composition-climate model to quantify near-future (2030 A1B) global annual mean radiative forcing by ozone (O3) and sulfate from six emissions sectors in seven geographic regions. At 2030 the net forcings from O3, sulfate, black and organic carbon, and indirect CH4 effects for each emission sector are (in mWm-2) biomass burning, +95; domestic, +68; transportation, +67; industry, -131; and power, -224. Biomass burning emissions in East Asia and central and southern Africa, domestic biofuel emissions in East Asia, south Asia, and central and southern Africa, and transportation emissions in Europe and North America have large net positive forcings and are therefore attractive targets to counter global warming. Power and industry emissions from East Asia, south Asia, and north Africa and the Middle East have large net negative forcings. Therefore air quality control measures that affect these regional sectors require offsetting climate measures to avoid a warming impact. Linear relationships exist between O3 forcing and biomass burning and domestic biofuel CO precursor emissions independent of region with sensitivity of +0.2 mWm-2/TgCO. Similarly, linear relationships exist between sulfate forcing and SO2 precursor emissions that depend upon region but are independent of sector with sensitivities ranging from -3 to -12 mWm-2/TgS.

Unger, Nadine; Shindell, Drew T.; Koch, Dorothy M.; Streets, David G.

2008-01-01

39

Air Quality – monitoring and modelling  

Directory of Open Access Journals (Sweden)

Full Text Available Air pollution is a major concern for all nations, regardless of their development. The rapid growth of the industrial sector and urban development have lead to significant quantities of substances and toxic materials, mostly discharged into the atmosphere and having adverse effects both on human health and environment in general. Human society has to recognize that environment has only a limited capacity to process all of its waste without major changes. Each of us is a pollutant but also a victim of pollution. If monitoring of air pollutants is particularly important for assessing the air quality at any moment, by modelling the monitoring data spectacular results are obtained both through the factor analysis and identification of potential pollution mitigation measures. Latest equipment and techniques come and support these problems giving medium and long term solutions.

Marius DEACONU

2012-12-01

40

Assessment of cosmic radiation doses received by air crew  

International Nuclear Information System (INIS)

Cosmic radiation in the atmosphere is such a complex mixture of radiation type that it is difficult to get a single instrument which is suitable for such measurements. Passive devices such as film badges and track etch detectors have also been used, but again present difficulties of interpretation and requirements of multiple devices to accommodate the different types of radiation encountered. In summary, air crew are the occupational group most highly exposed to radiation. The radiation doses experienced by them are sufficiently high as to require assessment on a regular basis and possible control by appropriate rostering. There appears little possibility of the dose limit for workers being exceeded, except possibly in the case of pregnant female crew. This category of air crew should be the subject of special controls aimed at ensuring that the dose limits for the foetus should not be exceeded

41

Passive radiative cooling below ambient air temperature under direct sunlight.  

Science.gov (United States)

Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning, for example, accounts for nearly fifteen per cent of the primary energy used by buildings in the United States. A passive cooling strategy that cools without any electricity input could therefore have a significant impact on global energy consumption. To achieve cooling one needs to be able to reach and maintain a temperature below that of the ambient air. At night, passive cooling below ambient air temperature has been demonstrated using a technique known as radiative cooling, in which a device exposed to the sky is used to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres. Peak cooling demand, however, occurs during the daytime. Daytime radiative cooling to a temperature below ambient of a surface under direct sunlight has not been achieved because sky access during the day results in heating of the radiative cooler by the Sun. Here, we experimentally demonstrate radiative cooling to nearly 5 degrees Celsius below the ambient air temperature under direct sunlight. Using a thermal photonic approach, we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. When exposed to direct sunlight exceeding 850 watts per square metre on a rooftop, the photonic radiative cooler cools to 4.9 degrees Celsius below ambient air temperature, and has a cooling power of 40.1 watts per square metre at ambient air temperature. These results demonstrate that a tailored, photonic approach can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day. PMID:25428501

Raman, Aaswath P; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui

2014-11-27

42

Air Temperature estimation from Land Surface temperature and solar Radiation parameters  

Science.gov (United States)

Air Temperature (AirT) is a fundamental parameter in a wide range of applications such as climate change studies, weather forecast, energy balance modeling, efficiency of Photovoltaic (PV) solar cells, etc. Air temperature data are generally obtained through regular measurements from meteorological stations. The distribution of these stations is normally sparse, so the spatial pattern of this parameter cannot be accurately estimated by interpolation methods. This work investigated the relationship between Air Temperature measured at meteorological stations and spatially contiguous measurements derived from Remote Sensing techniques, such as Land Surface Temperature (LST) maps, emissivity maps and shortwave radiation maps with the aim of creating a continuous map of AirT. For LST and emissivity, MSG-SEVIRI LST product from Land Surface Analysis Satellite Applications Facility (LSA-SAF) has been used. For shortwave radiation maps, an Artificial Neural Networks ensemble model has been developed and previously tested to create continuous maps from Global Horizontal Irradiance (GHI) point measurements, utilizing six thermal channels of MSG-SEVIRI. The testing sites corresponded to three meteorological stations located in the United Arab Emirates (UAE), where in situ measurements of Air Temperature were available. From the starting parameters, energy fluxes and net radiation have been calculated, in order to have information on the incoming and outgoing long-wave radiation and the incoming short-wave radiation. The preliminary analysis (day and Night measurements, cloud free) showed a strong negative correlation (0.92) between Outgoing long-wave radiation - GHI and LST- AirT, with a RMSE of 1.84 K in the AirT estimation from the initial parameters. Regression coefficients have been determined and tested on all the ground stations. The analysis also demonstrated the predominant impact of the incoming short-wave radiation in the AirT hourly variation, while the incoming long-wave radiation remains almost constant during the testing period. To conclude, the final AirT maps have been used to calculate continuous maps of Net Radiation, showing an important application of the output of this work for surface energy balance retrieval.

Lazzarini, Michele; Eissa, Yehia; Marpu, Prashanth; Ghedira, Hosni

2013-04-01

43

Radiation measurement of civil air flight  

International Nuclear Information System (INIS)

In order to aquire knowledge of the radiation exposure of civil aircrew members in common flight altitudes, it was necessary to develop a practicable measurement system. Radiation exposure was hereby estimated by using the ACREM-System, which is patented by the Austrian Research Centres Seibersdorf (OEFZS). Total Equivalent Dose could be estimated in a simple way by combining a measured component of the radiation field in flight altitudes and the results of simulation with LUIN 94 particle transport code (Keran O'Brian). To verify the results of the measurement system, a tissue equivalent proportional counter (TEPC) was used. Because of the difficult measurement conditions in cargo airplanes, special attention had to be taken to make the measurement equipment easy to use and transport. Special software has been developed to automate the measurement and the evaluation of the large amount of collected data. Measurements in standard calibration photon fields for the characterization of the equipment could be performed at the Primary Dosimetry Laboratory for Austria at the Austrian Research Centre (OEFZS) in Seibersdorf. Additional measurements were performed at Physikalisch Technische Bundesanstalt Braunschweig (PTB, Germany) and Paul Scherer Institute (PSI, Switzerland) to determine the reponse of the instruments to high energy photon and standard neutron fields. (author)

44

Radiation exposure on different air routes  

International Nuclear Information System (INIS)

Radiation exposure of aircrew personnel has obtained special emphasis by a European Council decision to consider the increased radiation level at high altitudes in the Earth's atmosphere as occupational exposure. The radiation field at typical jet cruising altitudes arises from cascade-like interaction processes of primary cosmic rays with the top layers of the atmosphere and is composed of various charged and uncharged particles in a broad energy range. The metrological assessment of all constituents with reasonable detection efficiency commonly requires a large set of experimental devices. Lithium fluoride thermoluminescent dosemeters (TLDs) evaluated according to the high-temperature ratio (HTR) method represent an appropriate alternative. The methodology was developed at the Atomic Institute of the Austrian Universities to determine absorbed dose and average LET of a mixed radiation field of unknown composition. The relative intensity of combined peaks 6 and 7 in the LiF glow curve compared with the main peak 5 are used as an indication of the average LET. Extensive irradiation campaigns with high-energy ions of different Z ranging from H to Fe established a HTR vs. LET calibration curve. The HTR method has previously been applied with great success on several space missions (including measurements onboard space station Mir, space shuttles, bio-satellites and the International Space Station) as well as in radiotherapeutic dosimetry. Within this paper measurements on several north-bound and equatorial flight routes originating from Vienna, Austria, and Cologne, Germany, are reviewed. The obtained route dose rates range from 2.1 ?Sv/h to 6.7 ?Sv/h and are compared with Monte Carlo simulations by means of the well-established algorithm CARI-6M, taking into account accurate route and altitude profiles on a 10-minutes scale. Contrary to previous releases of the program, the CARI-6M calculations proved to be in general agreement with the experimental data, although the values for north-bound routes are still underestimated by up to 15 % as neutrons contribute roughly 60 % of the dose equivalent. However, the most important insufficiency common to all simulations concerns the treatment of irregularly occurring solar flares. (author)

45

Chandra Radiation Environment Modeling  

Science.gov (United States)

CRMFLX (Chandra Radiation Model of ion FluX) is a radiation environment risk mitigation tool for use as a decision aid in planning the operations times for Chandra's Advanced CCD Imaging Spectrometer (ACIS) detector. The accurate prediction of the proton flux environment with energies of 100 - 200 keV is needed in order to protect the ACIS detector against proton degradation. Unfortunately, protons of this energy are abundant in the region of space Chandra must operate, and on-board particle detectors do not measure proton flux levels of the required energy range. This presentation will describe the plasma environment data analysis and modeling basis of the CRMFLX engineering environment model developed to predict the proton flux in the solar wind, magnetosheath, and magnetosphere phenomenological regions of geospace. The recently released CRMFLX Version 2 implementation includes an algorithm that propagates flux from an observation location to other regions of the magnetosphere based on convective ExB and VB-curvature particle drift motions. This technique has the advantage of more completely filling out the database and makes maximum use of limited data obtained during high Kp periods or in areas of the magnetosphere with poor satellite flux measurement coverage.

Minow, Joseph I.; Blackwell, W. C.

2003-01-01

46

Radiative divertor modeling studies  

International Nuclear Information System (INIS)

A two-dimensional fluid code called UEDGE is used to simulate the edge plasma in tokamak divertors and to evaluate methods for reducing the heat load on divertor plates by radiating some of the power before it reaches the plates. UEDGE is a fully-implicit code being developed jointly by us, D. A. Knoll and R. B. Campbell. For these studies, UEDGE uses a banded matrix solver and a fixed-fraction impurity model. Work is presently underway with Knoll and Campbell to include a memory-efficient iterative solver and a model of impurity transport. Simulations of the proposed TPX device show that a few percent nitrogen concentration in the scrape-off layer can radiate up to 80% of the divertor power, thus reducing the peak heat flux and electron temperature at the divertor plate to acceptable values. A comparison of the neutral gas distribution from UEDGE with results from the DEGAS Monte Carlo neutrals code confirms the validity of our fluid neutrals model

47

Radiative divertor modeling studies  

International Nuclear Information System (INIS)

A two-dimensional fluid code called UEDGE is used to simulate the edge plasma in tokamak divertors and to evaluate methods for reducing the heat load on divertor plates by radiating some of the power before it reaches the plates. UEDGE is a fully-implicit code being developed jointly by us, R.B. Campbell and D.A. Knoll. For these studies, UEDGE uses a banded matrix solver and a fixed-fraction impurity model. Work is presently underway with Campbell and Knoll to include a memory-efficient iterative solver and a model of impurity transport. Simulations of the proposed TPX device show that a few percent nitrogen concentration in the scrape-off layer can radiate up to 80% of the divertor power, thus reducing the peak heat flux and electron temperature at the divertor plate to acceptable values. A comparison of the neutral gas distribution from the DEGAS Monte Carlo neutrals code confirms the validity of our fluid neutrals model. (author) 12 refs., 8 figs

48

NIRATAM-NATO infrared air target model  

Science.gov (United States)

NIRATAM (the NATO Infrared Air Target Model) was developed by the NATO AC 243, Panel IV, Research Study Group 6 (RSG-6). RSG-6 is composed of representatives from Denmark, France, Germany, Italy, the Netherlands, the United Kingdom, the United States of America, and Canada (as an observer). NIRATAM is based on theoretical studies, field measurements, and infrared data analysis performed over many years. The model encompasses all the major signature components required to simulate the infrared signature of an aircraft and the atmosphere. The vehicle fuselage, facet, model includes radiation due to aerodynamic heating, internal heat sources, reflected sky, earth, and solar radiation. Plume combustion gas emissions are calculated for H(subscript 2)O, CO(subscript 2), CO, and other gases as well as solid particles. Lowtran 7 is used for the atmospheric transmission and radiance. The software generates graphical outputs of the target wireframe, plume flowfield, atmospheric transmission, total signature, and plume signature. Imagery data can be used for system development and evaluation. NIRATAM can be used for many applications such as measurement planning, data analysis, systems design, and aircraft development. Ontar has agreed to assist the RSG-6 by being the NIRATAM distribution center in the United States for users approved by the national representatives. Arrangements have also been made to distribute a user-friendly NIRATAM interface. This paper describes the model, presents results, makes comparisons with measured field data, and describes the availability and procedure for obtaining the software.

Noah, Meg A.; Kristl, Joseph; Schroeder, John W.; Sandford, B. P.

1991-08-01

49

Cosmic radiation exposure in subsonic air transport  

Science.gov (United States)

Data derived from 1973 statistics on 2.99 million intercity flights carrying 468 million seats were included in the calculations, yielding a total of 581 billion seat-kilometer. The average flight was 1,084 km in length, was flown at an altitude of 9.47 km, and lasted 1.41 h. The average dose rate was 0.20 mrem/h, resulting in an average passenger dose of 2.82 mrem/year and an average crewmember dose of 160 mrem/year. The average radiation dose to the total U.S. population was 0.47 mrem/person/year. These results are in good agreement with data from several experiments performed by us and others in aircraft at various altitudes and latitudes. The significance of these doses to the population is discussed.

Wallace, R. W.; Sondhaus, C. A.

1978-01-01

50

Statistical modeling of air pollution.  

Science.gov (United States)

The present communication deals with the application of several chemometric methods (principal components analysis, source apportioning on absolute principal components scores, chemical mass balance, self-organizing maps) to various aerosol data collections from different regions in Europe. It is shown that different latent factors explaining over 75 % of the total variance are responsible for the data structure and could be reliable identified and interpreted. Further, the contribution of each identified source to the formation of the particle total mass and chemical compounds total concentration is calculated. Thus, a reliable assessment of the air quality in the respective region is done. Classification by self-organizing maps makes it possible to better understand the role of different discriminating tracers in the air pollution. The use of chemical mass balance approach ensures a sound modeling of the pollution sources. The requirements of the sustainability concept for ecological indicators in this case is easily transformed to a multivariate statistical problem taking into account not separate indicators but the specific multivariate nature of the aerosol pollution. PMID:22217080

Tsakovski, Stefan L; Simeonova, Pavlina A; Simeonov, Vasil D

2012-01-01

51

Stochastic Modeling of Traffic Air Pollution  

DEFF Research Database (Denmark)

In this paper, modeling of traffic air pollution is discussed with special reference to infrastructures. A number of subjects related to health effects of air pollution and the different types of pollutants are briefly presented. A simple model for estimating the social cost of traffic related air pollution is derived. Several authors have published papers on this very complicated subject, but no stochastic modelling procedure have obtained general acceptance. The subject is discussed basis of a deterministic model. However, it is straightforward to modify this model to include uncertain parameters and using simple Monte Carlo techniques to obtain a stochastic estimate of the costs of traffic air pollution for infrastructures.

Thoft-Christensen, Palle

2014-01-01

52

Optical Diagnostics and Radiative Emission of Air Plasmas  

Science.gov (United States)

The radiation emitted by air plasmas is an essential consideration for the design of heat shields in atmospheric re-entry applications. Although re-entry generates non -equilibrium conditions, the relevant radiative parameters may be investigated in an equilibrium air plasma as well. In this study, an atmospheric pressure air plasma was generated using a radio-frequency inductively coupled plasma torch, and optical diagnostics were developed to measure the thermodynamic state and radiative emission of the plasma. Measurements were then compared with results of numerical codes which were subsequently improved from the basis of this work. Electronic, vibrational, and rotational temperatures, along with electron number densities, were measured at the exit plane of the plasma torch by means of emission spectroscopy. All results indicated that the plasma was close to local thermodynamic equilibrium. The maximum temperature and degree of ionization were 7600 K and 0.1%, respectively. The spectrum emitted by the plasma was measured from the ultraviolet to the near infra-red (2000 to 8000 A). After correction for the spectral response of the detection system and absolute intensity calibration, this spectrum provided a benchmark for the testing of radiative codes. Detailed comparisons were then made with numerical simulations performed with the NEQAIR code of Park (1985). These comparisons led to a number of enhancements to the radiative module of NEQAIR. In particular, the radiative transition probability database of NEQAIR was replaced with accurate results based on reliable spectroscopic constants and ab initio electronic transition moments. Also, intense radiating systems in the ultraviolet, such as NO delta and NO epsilon, were added to the code. By these improvements, NEQAIR now reproduces the benchmark spectrum from 2000 to 8000 A with an accuracy better than 20%. Separate, independent measurements of the air plasma's radiative source strength were also performed for temperatures between 4500 and 7500 K. While the original NEQAIR under-predicted the source strength by up to a factor 3.5 in this temperature range, simulations performed with the enhanced NEQAIR are within 20% of the measurements. These source strength measurements thus further confirm the accuracy of the improved NEQAIR code.

Laux, Christophe Olivier

53

Air crew exposure to cosmic radiation. New analysis, recommendations EURADOS  

International Nuclear Information System (INIS)

Cosmic radiation on the board of an aircraft consist of two components: directly ionizing radiation (electron, proton - low LET) and neutrons (high LET). Neither composition nor the energy spectrum of usual on-Earth calibration sources (60Co, 252Cf) do not correspond to the field on a board. Therefore high energy reference fields behind shielding high energy accelerator at CERN and Dubna have been created and intensively studied. Their typical characteristics following from the results of our measurements were obtained. In-flight measurements on the board of commercial aircraft have been realized since 1991 during about 20 flights, Flight routes extended from the 1.3 grad N up to about 65 grad N, flying altitudes varied from 8.2 km to 12.5 km. The exposure level due to galactic cosmic radiation is inversely proportional to the solar activity. Some radiation protection aspects were concluded: (a) The usual limits of annual air crew flight hours correspond at 11.3 km to about 4 mSv per year, with new ICRP conversion factors to about 5 mSv per year; (b) Monthly flight hours limit does not exclude that the exposure of a pregnant women can exceed 1 mSv during this period; (c) The air crew exposure should therefore be checked, controlled a nd administered as conscientiously as for any other group of occupationally exposed persons. A Working group 11 of EURADOS 'Exposure of air crew to cosmic radiation' has been formed (1992-1995) to prepare basic analysis and recommendations concerning the topics. The basic recommendations are the following: (a) air crew flying routinely at altitudes over 8 km are deemed to be category B workers, it is therefore important to estimate, record, control and, where necessary, to limit the doses; (b) the preferred procedure in order to estimate doses to air crew or frequent flyers is to determine route doses and fold these data with data on staff rostering; (c) where doses may exceed the limit for category B workers (6 mSv per year), on-board monitoring of dose may be appropriate; (d) an equivalent-dose limit of 1 mSv for the embryo and foetus should be specify for air crew (J.K.). 2 tabs., 12 refs

54

Two Dimensional Air Drop Model  

Science.gov (United States)

This interactive simulation shows an airplane flying at constant horizontal velocity preparing to drop relief supplies to a small island. Download Simulation Below As captain of the plane, you must determine when to release the package and activate the release button. The trajectory of the falling package is traced onscreen. If you were too far off, the package will drop in the ocean. The motion can be viewed from the perspective of a person standing on the island or an airplane flying nearby. Extend the learning by activating air friction to see how this variable affects the motion of the projectile. Editor's Note: Students may insist that there is a horizontal force acting upon the package since it has a horizontal motion. See Annotation for an editor-recommended tutorial that will explain what is happening (the horizontal motion of the package results from its inertia). This item was created with Easy Java Simulations (EJS), a modeling tool that allows users without formal programming experience to generate computer models and simulations.

Francisco Esquembre

2014-06-12

55

Air pollution model for point source  

Directory of Open Access Journals (Sweden)

Full Text Available Mathematical models of air pollution have a broad practical application. They are irreplaceable wherever it is not possible to determine a state of air pollution by measuring of a noxious agent concentration. By creating of a suitable model of air pollution we can assess a state of the air quality but we also to predict the pollution that can occur at given atmospheric conditions. The created model is a suitable tool for controlling the activity of TEKO and for the evaluation of the quality of air in a monitored area of the city of Košice. A sufficient knowledge in the given field is a condition. The input data and information necessary for creating such a model of polluted air is another important factor.

Jozef Ma?ala

2006-12-01

56

Simulating aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe haze conditions in winter  

OpenAIRE

The aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe winter haze conditions during January~2013 are simulated using the fully coupled on-line Weather Research and Forecasting/Chemistry (WRF-Chem) model. Three simulation scenarios including different aerosol configurations are undertaken to distinguish the impact of aerosol radiative (direct and semi-direct) and indirect effects on meteorological variables and air qua...

Zhang, B.; Wang, Y. X.; Hao, J. M.

2014-01-01

57

Solar radiation estimation using sunshine hour and air pollution index in China  

International Nuclear Information System (INIS)

Highlights: • Aerosol can affect coefficients of A–P equation to estimate solar radiation. • Logarithmic model performed best, according to MBE, MABE, MPE, MAPE, RMSE and NSE. • Parameters of A–P model can be adjusted by API, geographical position and altitude. • A general equation to estimate solar radiation was established in China. - Abstract: Angström–Prescott (A–P) equation is the most widely used empirical relationship to estimate global solar radiation from sunshine hours. A new approach based on Air Pollution Index (API) data is introduced to adjust the coefficients of A–P equation in this study. Based on daily solar radiation, sunshine hours and API data at nine meteorological stations from 2001 to 2011 in China, linear, exponential and logarithmic models are developed and validated. When evaluated by performance indicators of mean bias error, mean absolute bias error, mean percentage error, mean absolute percentage error, root mean square error, and Nash–Sutcliffe Equation, it is demonstrated that logarithmic model performed better than the other models. Then empirical coefficients for three models are given for each station and the variations of these coefficients are affected by API, geographical position, and altitude. This indicates that aerosol can play an important role in estimation solar radiation from sunshine hours, especially in those highly polluted regions. Finally, a countrywide general equation is established based on the sunshine hour data, API and geographical parameters, which can be used to estimate the daily solar radiation in areas where the radiation data is not available

58

Alleviating operating temperature of concentration solar cell by air active cooling and surface radiation  

International Nuclear Information System (INIS)

In the present paper, a heat transfer model for a multi-junction concentrating solar cell system has been developed. The model presented in this work includes the GaInP/GaAs/Ge triple-junction solar cell with a ventilation system in which air is forced to flow within a duct behind the solar cell assembly and its holders and accessories (anti-reflective glass cover, adhesive material, and aluminum back plate). A mathematical model for the entire system is presented and the finite difference technique has been used to solve the governing equations. Results showed that the interaction of surface radiation and air convection could adequately cool the solar cell at medium concentration ratios. For high concentration ratios, the channel width would need to be narrowed to micro-meter values to maintain the required efficiency of cooling. The conjugation effect has been shown to be significant and has a noticeable effect on the maximum solar cell temperature. Furthermore, the air inlet velocity and channel width were also found to have major effects on the cell temperature. -- Highlights: • A model has been developed to predict the solar cell temperature cooling by air. • Cell temperature can be remarkably reduced with the presence of surface radiation. • Cell temperature is extremely dependent on air inlet velocity and channel width. • Conjugation effect has a noticeable effect on the maximum solar cell temperature

59

Drying Strategy of Shrimp using Hot Air Convection and Hybrid Infrared Radiation/Hot Air Convection  

Directory of Open Access Journals (Sweden)

Full Text Available The main objective of the research was to study the effect of drying temperatures using infrared irradiation and electric heating convection on dehydration and was to investigate the effect of drying conditions on the quality of the shrimp. Two sizes of fresh shrimp (100 shrimp/kg and 200 shrimp/kg with initial moisture content of 270 - 350 % dry-basis were dried under various conditions while the final moisture content of dried shrimp was in ranges between 20 and 25 % dry-basis. Hot air flow rates of 1.0 -   1.2 m/s, drying temperatures of 40 - 90 °C and infrared intensities of 1,785.7 - 3,571.4 W/m2 were used in these experiments. The experimental results showed that the rate of moisture content transfer of both sizes of shrimps decreased exponentially with drying time while increasing drying temperature significantly affected to the drying kinetics and quality of the shrimps. Effective diffusion coefficients of both shrimps were determined by a diffusion model forming a finite cylindrical shape was in order of 10-7 m2/s and this effective diffusion coefficient value was relatively dependent on the drying temperature compared to the initial moisture content. The quality analysis of dried shrimp using an infrared source and electric heating source found that the redness value (Hunter a-value of dried samples using hybrid infrared radiation and electric heating had a higher colour uniformity than other drying methods. Additionally, shrinkage and rehydration properties were insignificantly different for all drying strategies (p < 0.05 and drying using infrared radiation had higher drying rates compared to electric heat convection, corresponding to relatively low drying times.

Supawan TIRAWANICHAKUL

2008-01-01

60

Waveform-Controlled Terahertz Radiation from the Air Filament Produced by Few-Cycle Laser Pulses  

CERN Document Server

Waveform-controlled Terahertz (THz) radiation is of great importance due to its potential application in THz sensing and coherent control of quantum systems. We demonstrated a novel scheme to generate waveform-controlled THz radiation from air plasma produced when carrier-envelope-phase (CEP) stabilized few-cycle laser pulses undergo filamentation in ambient air. We launched CEP-stabilized 10 fs-long (~ 1.7 optical cycles) laser pulses at 1.8 {\\mu}m into air and found that the generated THz waveform can be controlled by varying the filament length and the CEP of driving laser pulses. Calculations using the photocurrent model and including the propagation effects well reproduce the experimental results, and the origins of various phase shifts in the filament are elucidated.

Bai, Ya; Xu, Rongjie; Li, Chuang; Liu, Peng; Zeng, Zhinan; Zhang, Zongxin; Lu, Haihe; Li, Ruxin; Xu, Zhizhan

2012-01-01

61

Multi-Group Reductions of LTE Air Plasma Radiative Transfer in Cylindrical Geometries  

Science.gov (United States)

Air plasma radiation in Local Thermodynamic Equilibrium (LTE) within cylindrical geometries is studied with an application towards modeling the radiative transfer inside arc-constrictors, a central component of constricted-arc arc jets. A detailed database of spectral absorption coefficients for LTE air is formulated using the NEQAIR code developed at NASA Ames Research Center. The database stores calculated absorption coefficients for 1,051,755 wavelengths between 0.04 µm and 200 µm over a wide temperature (500K to 15 000K) and pressure (0.1 atm to 10.0 atm) range. The multi-group method for spectral reduction is studied by generating a range of reductions including pure binning and banding reductions from the detailed absorption coefficient database. The accuracy of each reduction is compared to line-by-line calculations for cylindrical temperature profiles resembling typical profiles found in arc-constrictors. It is found that a reduction of only 1000 groups is sufficient to accurately model the LTE air radiation over a large temperature and pressure range. In addition to the reduction comparison, the cylindrical-slab formulation is compared with the finite-volume method for the numerical integration of the radiative flux inside cylinders with varying length. It is determined that cylindrical-slabs can be used to accurately model most arc-constrictors due to their high length to radius ratios.

Scoggins, James; Magin, Thierry Edouard Bertran; Wray, Alan; Mansour, Nagi N.

2013-01-01

62

Impact of Asian Dust on Global Surface Air Quality and Radiation Budget  

Science.gov (United States)

Dust originating from Asian deserts and desertification areas can be transported regionally and globally to affect surface air quality, visibility, and radiation budget not only at immediate downwind locations (e.g., eastern Asia) but also regions far away from the sources (e.g., North America). Deposition of Asian dust to the North Pacific Ocean basin influences the ocean productivity. In this study, we will use the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, remote sensing data form satellite and from the ground-based network, and in-situ data from aircraft and surface observations to address the following questions: - What are the effects of Asian dust on the surface air quality and visibility over Asia and North America? - What are the seasonal and spatial variations of dust deposition to the North Pacific Ocean? How does the Asian dust affect surface radiation budget?

Chin, Mian; Diehl, Thomas; Yu, Hongbin; Ginoux, Paul

2006-01-01

63

Simulation model air-to-air plate heat exchanger  

International Nuclear Information System (INIS)

A simple simulation model of an air-to-air plate heat exchanger is presented. The model belongs to a collection of simulation models that allows the efficient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is to shorten computation time and to use only input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part-load operation mode, which is becoming increasingly important in energy efficient HVAC systems. The models are intended to be used for yearly energy calculations or load calculations with time steps of about 10 minutes or larger. Short- time dynamic effects, which are of interest for different aspects of control theory, are neglected. The part-load behavior is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part-load condition. If the heat transfer coefficients on the two exchanger sides are not equal (i. e. due to partial bypassing of air), their ratio can be easily calculated and set as a parameter. The model is static and uses explicit equations only. The explicit model formulation ensures short computation time and numerical stability, which allows using the model with sophisticated engineering methods like automatic system optimization. This paper fully outlines the algorithm description and its simplifications. It is not tailored for any particular simulation program to ensure easy implementation in any simulation program

64

Air quality modeling in Warsaw Metropolitan Area  

OpenAIRE

Decision support of air quality management needs to connect several categories of the input data with the analytical process of air pollution dispersion. The aim of the respective model of air pollution is to provide a quantitative assessment of environmental impact of emission sources in a form of spatial/temporal maps of pollutants’ concentration or deposition in the domain. These results are in turn used in assessment of environmental risk and supporting respective planning actions. Howe...

Piotr Holnicki; Zbigniew Nahorski

2013-01-01

65

Ab Initio Modeling of Molecular Radiation  

Science.gov (United States)

Radiative emission from excited states of atoms and molecules can comprise a significant fraction of the total heat flux experienced by spacecraft during atmospheric entry at hypersonic speeds. For spacecraft with ablating heat shields, some of this radiative flux can be absorbed by molecular constituents in the boundary layer that are formed by the ablation process. Ab initio quantum mechanical calculations are carried out to predict the strengths of these emission and absorption processes. This talk will describe the methods used in these calculations using, as examples, the 4th positive emission bands of CO and the 1g+ 1u+ absorption in C3. The results of these calculations are being used as input to NASA radiation modeling codes like NeqAir, HARA and HyperRad.

Jaffe, Richard; Schwenke, David

2014-01-01

66

Air permeability of several radiation-grafted films  

Energy Technology Data Exchange (ETDEWEB)

An automatic apparatus for measuring the permeability coefficient and the oxygen content in permeated air based on low vacuum method was designed to investigate the gas permeability of polymer films. With above apparatus, experiments were performed on several radiation-grafted films and those modified by combining organic cobalt complex compounds. Remarkable lowering of permeability coefficients alongwith raising of oxygen content in permeated air was observed with the increase in extent of grafting on polyethylene-g-polymaleimide, -g-poly(maleic anhydride), poly(ethylene-co-vinyl acetate)-g-poly(methacrylic acid), -g-poly(4-vinyl pyridine) films, and so forth, whereas the changes in permeability and oxygen separation ability with the increase in extent of grafting were insignificant on silicone-g-poly(methacrylic acid) and -g-poly(4-vinyl pyridine) films. Positive result on permeability was obtained concerning the effect of combining organic cobalt complex compounds on some grafted films. (author).

Hayakawa, Kiyoshi; Tazawa, Masato; Yamakita, Hiromi (Government Industrial Research Inst., Nagoya (Japan))

1989-09-01

67

Air permeability of several radiation-grafted films  

International Nuclear Information System (INIS)

An automatic apparatus for measuring the permeability coefficient and the oxygen content in permeated air based on low vacuum method was designed to investigate the gas permeability of polymer films. With above apparatus, experiments were performed on several radiation-grafted films and those modified by combining organic cobalt complex compounds. Remarkable lowering of permeability coefficients alongwith raising of oxygen content in permeated air was observed with the increase in extent of grafting on polyethylene-g-polymaleimide, -g-poly(maleic anhydride), poly(ethylene-co-vinyl acetate)-g-poly(methacrylic acid), -g-poly(4-vinyl pyridine) films, and so forth, whereas the changes in permeability and oxygen separation ability with the increase in extent of grafting were insignificant on silicone-g-poly(methacrylic acid) and -g-poly(4-vinyl pyridine) films. Positive result on permeability was obtained concerning the effect of combining organic cobalt complex compounds on some grafted films. (author)

68

Radiation hazard due to radon in indoor air  

International Nuclear Information System (INIS)

Inhalation of the noble gas radon and its short-lived daughter products present in normal room air causes a considerable increase of the mean natural radiation exposure of the population. As there is an uncontested relationship between lung dose and cancer risk, measures should be taken to guarantee that the radon concentrations in room air do at least not reach maxima. The most simple measure is frequent, brief, good ventilation. Very high radon concentrations are measured in houses where radon pentrates direct from the soil into buildings. For this case, radon-tight insulation of the building from the soil is recommended. A forced ventilation system with heat recovery, installed by experts, has shown to be very successful in radon reduction in 'problematic' houses. (orig.)

69

Calculation of molecular bremsstrahlung radiation and air shower plasma conditions for CROME  

International Nuclear Information System (INIS)

The possibility of the detection of extensive air showers by observation of isotropic microwave radiation due to molecular bremsstrahlung has been proposed in 2008. Ionization electrons, forming a short-lived, tenuous plasma in the wake of the shower, interact with atmospheric neutrals and produce bremsstrahlung. Concurrent with first measurements of microwave radiation by the CROME experiment in Karlsruhe, an independent, theory based model for emission of isotropic bremsstrahlung emission has been developed. In this talk, the assumptions of the model for bremsstrahlung emission and the findings concerning the state of the plasma in an air shower are discussed. The magnitude of the expected signal is calculated and compared to predictions made in the original proposal by Gorham et al. and to the observed GHz signals.

70

Radiation from ballistic-range-generated hypersonic air shock layers  

Science.gov (United States)

Preliminary studies of spectroscopic measurement of high-Mach-number air shock layers generated by a ballistic range were conducted. Using a spectrograph and highly-sensitive film system, the spectrogram of a shock layer at a flight velocity of higher than 3 km/sec was taken. These photographic data were transformed into numerical data using a digital-processing system composed of a CCD camera and an image processor. In the wavelength range from 350 nm to 440 nm, several band spectra which are due to N2 and CN were observed. In order to predict the experimental results at higher Mach numbers, numerical calculation of hypersonic flows around a blunt body were conducted. Radiation calculation were done using the NEQAIR program. In order to experimentally investigate the contributions of the respective species on radiative emission, a high-speed shuttering system using an image intensifier, along with the highly-sensitive film, has been set up.

Sasoh, A.; Chang, X.; Henmi, M.; Kasahara, J.; Fujiwara, T.

1992-03-01

71

Radiation safety of crew and passengers of air transportation in civil aviation. Provisional standards  

Science.gov (United States)

The purpose and application of the provisional standards for radiation safety of crew and passengers in civil aviation are given. The radiation effect of cosmic radiation in flight on civil aviation air transport is described. Standard levels of radiation and conditions of radiation safety are discussed.

Aksenov, A. F.; Burnazyan, A. I.

1985-01-01

72

Models of diffuse solar radiation  

Energy Technology Data Exchange (ETDEWEB)

For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the horizontal available. There are regression relationships for estimating the diffuse on a tilted surface from diffuse on the horizontal. Models for estimating the diffuse radiation on the horizontal from horizontal global that have been developed in Europe or North America have proved to be inadequate for Australia [Spencer JW. A comparison of methods for estimating hourly diffuse solar radiation from global solar radiation. Sol Energy 1982; 29(1): 19-32]. Boland et al. [Modelling the diffuse fraction of global solar radiation on a horizontal surface. Environmetrics 2001; 12: 103-16] developed a validated model for Australian conditions. We detail our recent advances in developing the theoretical framework for the approach reported therein, particularly the use of the logistic function instead of piecewise linear or simple nonlinear functions. Additionally, we have also constructed a method, using quadratic programming, for identifying values that are likely to be erroneous. This allows us to eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. (author)

Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia); Brown, Bruce [Department of Statistics and Applied Probability, National University of Singapore, Singapore 117546 (Singapore)

2008-04-15

73

MONET: multidimensional radiative cloud scene model  

Science.gov (United States)

All cloud fields exhibit variable structures (bulge) and heterogeneities in water distributions. With the development of multidimensional radiative models by the atmospheric community, it is now possible to describe horizontal heterogeneities of the cloud medium, to study these influences on radiative quantities. We have developed a complete radiative cloud scene generator, called MONET (French acronym for: MOdelisation des Nuages En Tridim.) to compute radiative cloud scene from visible to infrared wavelengths for various viewing and solar conditions, different spatial scales, and various locations on the Earth. MONET is composed of two parts: a cloud medium generator (CSSM -- Cloud Scene Simulation Model) developed by the Air Force Research Laboratory, and a multidimensional radiative code (SHDOM -- Spherical Harmonic Discrete Ordinate Method) developed at the University of Colorado by Evans. MONET computes images for several scenario defined by user inputs: date, location, viewing angles, wavelength, spatial resolution, meteorological conditions (atmospheric profiles, cloud types)... For the same cloud scene, we can output different viewing conditions, or/and various wavelengths. Shadowing effects on clouds or grounds are taken into account. This code is useful to study heterogeneity effects on satellite data for various cloud types and spatial resolutions, and to determine specifications of new imaging sensor.

Chervet, Patrick

1999-12-01

74

Impacts of future air pollution mitigation strategies on the aerosol direct radiative forcing over Europe  

Science.gov (United States)

Projections of aerosol emissions for 2030 have been recently generated and implemented in a comprehensive chemistry-transport model to analyse the future evolution of the aerosol radiative forcing over Europe. In this study, numerical developments based on an off-line coupling between the regional chemistry-transport model CHIMERE (extended by an aerosol optical module) and the radiative transfer code GAME have been implemented in order to simulate the interaction of physico-chemically resolved aerosols with radiation at regional scale. This novel approach is used to examine the shortwave aerosol direct radiative forcing response to two air pollution reduction scenarios for 2030 over Europe. Our study suggests that measures introduced to improve future air quality could have large implication on the aerosol climate forcing over Europe. Results of simulations indicate that abatement of aerosols in the near future could lead to a decrease of the aerosol cooling effect at the surface and at the top of the atmosphere over the main anthropogenic emission regions. Especially over the Moscow region, different strategies of reduction for scattering sulphate and absorbing black carbon aerosols between the two scenarios could result, however, in either a reduction or an enhancement in atmospheric radiative forcing.

Péré, J. C.; Colette, A.; Dubuisson, P.; Bessagnet, B.; Mallet, M.; Pont, V.

2012-12-01

75

Mixed conflict model for Air Traffic Control  

OpenAIRE

Airspace congestion is today the most critical issue European Air Traffic Management (ATM) has to face. Current real-time Air Traffic Control (ATC) is achieved by human controllers. One of their main tasks is to keep separation between aircraft, asking to the pilots to do basic avoidance manoeuvres. We propose here two mixed CSP models of this separation issue, combining discrete and continuous variables. An implementation of these models allows to produce optimal solutions for problems where...

Feydy, Thibaut; Barnier, Nicolas; Brisset, Pascal; Durand, Nicolas

2005-01-01

76

Correlation of diffuse solar radiation with air mass  

Energy Technology Data Exchange (ETDEWEB)

Measurements of total and diffuse components of solar radiation have been conducted using pyranometers at Zaria and Kano in northern Nigeria during the period when the dust-bearing north-easterly harmattan winds blow from the Sahara. The measurements have been made for several years and a correlation has been sought for the large amount of data obtained. By means of a simple theoretical consideration, it was shown that the main parameters are the mean optical thickness, the air mass and the diffuse ratio. Accordingly, the data for every hour has been processed to give these parameters and the optical thickness was plotted against the diffuse ratio for various ranges of air mass. The results portrayed a satisfactory correlation between the diffuse ratio and the optical thickness as well as the air mass. For the purpose of presentation in more conventional form, the results were transposed on to plots of diffuse ratio against clearness factor. In this way, the results become more amenable to comparison with related previous work.

Doyle, M.D.C.; Sambo, A.S.

1988-01-01

77

Surface Flux Modeling for Air Quality Applications  

Directory of Open Access Journals (Sweden)

Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

Limei Ran

2011-08-01

78

Modelling of radiation transport  

International Nuclear Information System (INIS)

In the application of nuclear radiation, the problem of the transport of photons and neutral or charged particles through the matter is central for understanding the physics of the process, for a correct interpretation of the measurement and for a convenient choice of instrumental operating conditions. This paper, in the first part, is intended as a survey of the genesis of the transport equations, which describe the phenomenon of the diffusion of the particles. With a regressive procedure, it is possible to obtain the commonly used transport equations directly from Liouville equation; the approximations that must always been involved can be related to two dimensionless parameters if suitable dimesionless variables are introduced. In the second part, approximate solutions of Boltzmann and Fokker-Planck equations are given for particular physical situations of interest in X-ray spectroscopy and electron microprobe analysis

79

Modelling of radiation transport  

Energy Technology Data Exchange (ETDEWEB)

In the application of nuclear radiation, the problem of the transport of photons and neutral or charged particles through the matter is central for understanding the physics of the process, for a correct interpretation of the measurement and for a convenient choice of instrumental operating conditions. This paper, in the first part, is intended as a survey of the genesis of the transport equations, which describe the phenomenon of the diffusion of the particles. With a regressive procedure, it is possible to obtain the commonly used transport equations directly from Liouville equation; the approximations that must always been involved can be related to two dimensionless parameters if suitable dimesionless variables are introduced. In the second part, approximate solutions of Boltzmann and Fokker-Planck equations are given for particular physical situations of interest in X-ray spectroscopy and electron microprobe analysis.

Molinari, V.G. E-mail: vincenzo.molinari@mail.ing.unibo.it; Manservisi, S.; Rocchi, F.; Teodori, F

2004-01-01

80

Experimental determination of isodose curves in the air for beta radiation and Bremsstrahlung  

International Nuclear Information System (INIS)

The values of absorbed radiation doses in the air were determined aiming to obtain the isodose curves, for beta radiation and for Bremsstrahlung radiation of a 85Kr source, in several distances. Mamography films and a scintillator detector were used. The method was efficient for determining the radiation field and can be used for industrial and medical sources. (E.G.)

81

Radiative transfer models  

Science.gov (United States)

The purpose of this work was to assist with the development of analytical techniques for the interpretation of infrared observations. We have done the following: (1) helped to develop models for continuum absorption calculations for water vapor in the far infrared spectral region; (2) worked on models for pressure-induced absorption for O2 and N2 and their comparison with available observations; and (3) developed preliminary studies of non-local thermal equilibrium effects in the upper stratosphere and mesosphere for infrared gases. These new techniques were employed for analysis of balloon-borne far infrared data by a group at the Harvard-Smithsonian Center for Astrophysics. The empirical continuum absorption model for water vapor in the far infrared spectral region and the pressure-induced N2 absorption model were found to give satisfactory results in the retrieval of the mixing ratios of a number of stratospheric trace constituents from balloon-borne far infrared observations.

Horwitz, James L.

1992-01-01

82

Detailed Radiative Transport Modeling of a Radiative Divertor  

CERN Document Server

An effective radiative divertor maximizes the utilization of atomic processes to spread out the energy deposition to the divertor chamber walls and to reduce the peak heat flux. Because the mixture of neutral atoms and ions in the divertor can be optically thick to a portion of radiated power, it is necessary to accurately model the magnitude and distribution of line radiation in this complex region. To assess their importance we calculate the effects of radiation transport using CRETIN, a multi-dimensional, non-local thermodynamic equilibrium simulation code that includes the atomic kinetics and radiative transport processes necessary to model the complex environment of a radiative divertor. We also include neutral transport to model radiation from recycling neutral atoms. This paper presents a case study of a high-recycling radiative divertor with a typical large neutral pressure at the divertor plate to estimate the impact of H line radiation on the overall power balance in the divertor region with conside...

Wan, A S; Scott, H A; Post, D; Rognlien, T D

1995-01-01

83

Regional Air Impact Modeling Initiative Data Miner  

Science.gov (United States)

Data Miner is a large client-server database processing system that provides access to large and complex databases and facilitates the assembly of multi-source emissions inventories to support air dispersion modeling and risk modeling. U.S. EPA developed Data Miner under the Regi...

84

A more accurate nonequilibrium air radiation code - NEQAIR second generation  

Science.gov (United States)

Two experiments, one an equilibrium flow in a plasma torch at Stanford, the other a nonequilibrium flow in a SDIO/IST Bow-Shock-Ultra-Violet missile flight, have provided the basis for modifying, enhancing, and testing the well-known radiation code, NEQAIR. The original code, herein termed NEQAIR1, lacked computational efficiency, accurate data for some species and the flexibility to handle a variety of species. The modified code, herein termed NEQAIR2, incorporates recent findings in the spectroscopic and radiation models. It can handle any number of species and radiative bands in a gas whose thermodynamic state can be described by up to four temperatures. It provides a new capability of computing very fine spectra in a reasonable CPU time, while including transport phenomena along the line of sight and the characteristics of instruments that were used in the measurements. Such a new tool should allow more accurate testing and diagnosis of the different physical models used in numerical simulations of radiating, low density, high energy flows.

Moreau, Stephane; Laux, Christophe O.; Chapman, Dean R.; MacCormack, Robert W.

1992-07-01

85

An air quality model for Central Mexico  

International Nuclear Information System (INIS)

A computational air quality model for Central Mexico that includes the Basin of the Valley of Mexico, the Valleys of Toluca, Puebla and Cuernavaca already in experimental operation, is presented. The meteorology of the region is obtained combining two non-hydrostatic models: a model designed for synoptic scales called MM5 provides initial and boundary data to a model specially designed for urban environments and scales called MEMO. The transport model used numerical techniques developed by the authors that eliminate numerical diffusion and dispersion. For the photochemical model several ODE's integrators were tested. The emissions model developed uses the latest inventory data gathered in the region. (Author)

86

A fitting formula for radiative cooling based on non-local thermodynamic equilibrium population from weakly-ionized air plasma  

Science.gov (United States)

A fitting formula for radiative cooling with collisional-radiative population for air plasma flowfield has been developed. Population number densities are calculated from rate equations in order to evaluate the effects of nonequilibrium atomic and molecular processes. Many elementary processes are integrated to be applied to optically-thin plasmas in the number density range of 1012/cm3 propagation with the nonequilibrium radiative cooling is conducted and successfully reproduces the shock and plasma wave front time history observed by experiments. In addition, from the comparison between numerical simulations with the radiation cooling effect based on the fitting formula and those with a gray gas radiation model that assumes local thermodynamic equilibrium, we find that the displacement of the plasma front is slightly different due to the deviation of population probabilities. By using the fitting formula, we can easily and more accurately evaluate the radiative cooling effect without solving detailed collisional-radiative rate equations.

Ogino, Yousuke; Nagano, Atsushi; Ishihara, Tomoaki; Ohnishi, Naofumi

2013-08-01

87

Biophysical models in radiation biology  

International Nuclear Information System (INIS)

Models serve a variety of purposes: to link physics and biology; to interpolate and extrapolate to dose regions where direct biological measurements of statistical significance are not feasible; to address basic mechanisms; to suggest new experiments designed to test hypotheses predicted by the model. In the past, the modeling arena has been dominated by dose-response curves for cell killing which have slowly but surely incorporated more and more of the biological factors that are known to be important. At the present time, the modelers urgently need to follow the revolution in the new biology as quantitative data become available. There are several areas involved: i. the relation between DNA strand breaks, initial breaks as measured by the premature chromosome condensation technique and cell lethality. ii. modeling of oncogenic transformation as a function of dose and of radiation quality. iii. modeling of oncogenic transformation as a function of oncogene activation. iv. modeling of oncogene activation and suppressor cell deletion as a function of radiation dose and radiation quality. (author)

88

Validation of the community radiative transfer model  

International Nuclear Information System (INIS)

To validate the Community Radiative Transfer Model (CRTM) developed by the U.S. Joint Center for Satellite Data Assimilation (JCSDA), the discrete ordinate radiative transfer (DISORT) model and the line-by-line radiative transfer model (LBLRTM) are combined in order to provide a reference benchmark. Compared with the benchmark, the CRTM appears quite accurate for both clear sky and ice cloud radiance simulations with RMS errors below 0.2 K, except for clouds with small ice particles. In a computer CPU run time comparison, the CRTM is faster than DISORT by approximately two orders of magnitude. Using the operational MODIS cloud products and the European Center for Medium-range Weather Forecasting (ECMWF) atmospheric profiles as an input, the CRTM is employed to simulate the Atmospheric Infrared Sounder (AIRS) radiances. The CRTM simulations are shown to be in reasonably close agreement with the AIRS measurements (the discrepancies are within 2 K in terms of brightness temperature difference). Furthermore, the impact of uncertainties in the input cloud properties and atmospheric profiles on the CRTM simulations has been assessed. The CRTM-based brightness temperatures (BTs) at the top of the atmosphere (TOA), for both thin (?30) clouds, are highly sensitive to uncertainties in atmospheric temperature and cloud top pressure. However, for an optically thick cloud, the CRTM-based BTs are not sensitive to the uncertainties of cloud optical thickness, effeainties of cloud optical thickness, effective particle size, and atmospheric humidity profiles. On the contrary, the uncertainties of the CRTM-based TOA BTs resulting from effective particle size and optical thickness are not negligible in an optically thin cloud.

89

Neural models project for solar radiation and atmospheric temperature forecast  

OpenAIRE

This work arises from the necessity of temperature and solar radiation forecast, to improve the Heating, Ventilating, and Air Conditioning (HVAC) systems e ciency. To do so, it was necessary to determine neural models capable of such forecast. The chosen characteristics were solar radiation and temperature because these two characteristics directly a ect the room temperature inside a building. This forecast system will be implemented on a portable computational device, so it mu...

Martins, I.

2009-01-01

90

Radiation doses and radiation hazards due to natural radioactivity in the air  

International Nuclear Information System (INIS)

The level of airborne radon decay products in a normal environment leads to a radiation exposure which may exceed 10000 mrem/a. An estimation of the resulting cancer risk involves many uncertainties, however this applies for other carcinogens to a much greater extent. There is no other carcinogen present in the normal environment about which so much is known through direct observation in man. As a consequence, of all carcinogens present in the normal environment, radon decay products are of major importance. Attention should be given, in particular, to airborne radon decay product levels in areas where higher concentrations may be expected. In the development and application of new biulding materials (eg. industrial gypsum utilisation of slag and ash from coal powerstations, by products of phosphate production) and new construction designs (eg. reduction of air exchange in rooms through extreme sealing of windows) it will have to be taken into consideration how these products will affect the radon decay product levels of the air in buildings. Future radiation protection legislation should therefore also include the natural radiation sources in our environment. In some countries the maximum permissible concentration of such radionuclides in biulding materials has already been legally imposed. By the same token water from natural sources should also be subject to licencing, and thus controllable should the content of certain radionuclides exceed certain limits. (orig.)ionuclides exceed certain limits. (orig.)

91

Air quality monitoring networks: Mathematical models  

Energy Technology Data Exchange (ETDEWEB)

The Health Ministry of Rome, Italy, (Istituto Superiore di Sanita) entrusted the Authors, all members of the Working Group on Air Quality Monitoring Networks, to investigate the possibility of using mathematical models in the design of these networks. In this paper, they point out the purpose of the monitoring networks, compare various types of statistical design tools and network models, and indicate the steps required to locate the sensors. A survey is done of marketed codes for the simulation of different air pollution/meteorological condition scenarios. Different sensor siting criteria are analyzed in order to stress the usefulness of standardization. The paper concludes with a review of proposed legislation on air pollution abatement in Italy.

Cirillo, M.C.; Finzi, G.; Fortezza, F.; Mamolini, G.; Marani, A.; Tamponi, M.; Tirabassi, T. (ENEA, Rome (Italy) Politecnico di Milano, Milan (Italy). Dipt. di Elettronica e Informazione USL 35, Ravenna (Italy) ENEL, Piacenza (Italy) Venice Univ. (Italy). Dipt. di Scienze Ambientali USSL 75/III, Milan (Italy) CNR, Bologna (Italy))

1992-09-01

92

The use of numerical flow models for predicting air flow and heat transfer in a room  

Energy Technology Data Exchange (ETDEWEB)

Air flow and heat transfer in a room are calculated by means of a combined heat radiation/flow model. The room is heated by a radiator situated below the window. The computer program used for air flow calculations is based on the program CHAMPION, which is able to solve equations for two-dimensional, stationary, turbulent flow. Heat exchange between walls, window and radiator are calculated with another program which has been coupled to the flow model. Results are presented. 11 figs., 5 tabs., 6 refs.

Van Tongeren, P.J.; Lemaire, A.D.

1987-09-01

93

Modelling the regional effects of climate change on air quality  

International Nuclear Information System (INIS)

The life cycle of pollutants is affected by chemical as well as meteorological factors, such as wind, temperature, precipitation, solar radiation. Therefore, climatic changes induced by anthropogenic emissions of greenhouse gases may be expected to have significant effects on air quality. Because of the spatial variability of the pollutant emissions and climate-change signals, these effects are particularly relevant at the regional to local scales. This paper first briefly reviews modelling tools and methodologies used to study regional climate-change impacts on air quality. Patterns of regional precipitation, temperature, and sea-level changes emerging from the latest set of general circulation model projections are then discussed. Finally, the specific case of climate-change effects on summer ozone concentrations over Europe is presented to illustrate the potential impacts of climate change on pollutant amounts. It is concluded that climate change is an important factor that needs to be taken into account when designing future pollution-reduction policies. (authors)

94

Radiation transfer in air and air-Cu plasmas for two temperature profiles  

Science.gov (United States)

In this article we present our results from calculations of the divergence of the radiation flux in a high temperature air-Cu plasma arc. We assumed stationary plasma, with local thermodynamic equilibrium valid throughout the plasma volume. We paid attention especially to the presence of copper lines in the absorption coefficient spectra and their influence on the energy transfer. Two distinct temperature regimes were used, with one focusing on a steep temperature gradient and the other involving a slowly varying temperature profile. The temperature ranges from 25 kK at the arc center down to 3 kK at the plasma arc boundary. Uniform pressure of 1 bar was considered in all cases. The results show that a large amount of energy is emitted by the copper vapor, which helps with cooling the arc.

Kloc, P.; Aubrecht, V.; Bartlova, M.; Coufal, O.

2015-02-01

95

Air Quality Response Modeling for Decision Support  

Directory of Open Access Journals (Sweden)

Full Text Available Air quality management relies on photochemical models to predict the responses of pollutant concentrations to changes in emissions. Such modeling is especially important for secondary pollutants such as ozone and fine particulate matter which vary nonlinearly with changes in emissions. Numerous techniques for probing pollutant-emission relationships within photochemical models have been developed and deployed for a variety of decision support applications. However, atmospheric response modeling remains complicated by the challenge of validating sensitivity results against observable data. This manuscript reviews the state of the science of atmospheric response modeling as well as efforts to characterize the accuracy and uncertainty of sensitivity results.

Sergey L. Napelenok

2011-08-01

96

Aerosol Modeling at the Air Force Weather Agency  

Science.gov (United States)

Aerosol modeling has a wide range of capabilities involving complex challenges. Research on aerosols being conducted at the Air Force Weather Agency (AFWA) includes studies on dust and volcanic ash forecasting. There are several models being utilized which allow investigations of emission, transport and deposition schemes. A brief overview of the updates made to the current models and ongoing research will be given. This will include an overview of the dust forecasting capabilities available utilizing the Dust Transport Application (DTA) and the Weather Research and Forecasting - Chemistry (WRF-CHEM) model coupled with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) dust model. A summary of the PUFF, Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), and Volcano WRF-CHEM models used for volcanic ash forecasting will also be provided.

George, K.; Elliott, A.

2011-12-01

97

Tracks FAQs: What is Modeled Air Data?  

Centers for Disease Control (CDC) Podcasts

In this podcast, CDC Tracking experts discuss modeled air data. Do you have a question for our Tracking experts? Please e-mail questions to trackingsupport@cdc.gov.  Created: 4/25/2011 by National Center for Environmental Health, Division of Environmental Hazards and Health Effects, Environmental Health Tracking Branch.   Date Released: 4/25/2011.

2011-04-25

98

Air quality modeling for emergency response applications  

International Nuclear Information System (INIS)

The three-dimensional diagnostic wind field model (MATHEW) and the particle-in-cell transport and diffusion model (ADPIC) are used by the Atmospheric Release Advisory Capability (ARAC) for real-time assessments of the consequences from accidental releases of radioactivity into the atmosphere. For the dispersion of hazardous heavier-than-air gases, a time-dependent, three-dimensional finite element model (FEM3) is used. These models have been evaluated extensively against a wide spectrum of field experiments involving the release of chemically inert tracers or heavier-than-air gases. The results reveal that the MATHEW/ADPIC models are capable of simulating the spatial and temporal distributions of tracer concentration to within a factor of 2 for 50% of the measured tracer concentrations for near surface releases in relatively flat terrain and within a factor of 2 for 20% of the comparisons for elevated releases in complex terrain. The FEM3 model produces quite satisfactory simulations of the spatial and temporal distributions of heavier-than-air gases, typically within a kilometer of the release point. The ARAC consists of a centralized computerized emergency response system that is capable of supporting up to 100 sites and providing real-time predictions of the consequence of transportation accidents that may occur anywhere. It utilizes pertinent accident information, local and regional meteorology, and terrain as input to the MATHEW/ADPIC models for the consequence analysis. It has responded to over 150 incidents and exercises over the past decade

99

Radiation dosimetry and biophysical models of space radiation effects  

Science.gov (United States)

Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

Cucinotta, Francis A.; Wu, Honglu; Shavers, Mark R.; George, Kerry

2003-01-01

100

Air freight demand models: An overview  

Science.gov (United States)

A survey is presented of some of the approaches which have been considered in freight demand estimation. The few existing continuous time computer simulations of aviation systems are reviewed, with a view toward the assessment of this approach as a tool for structuring air freight studies and for relating the different components of the air freight system. The variety of available data types and sources, without which the calibration, validation and the testing of both modal split and simulation models would be impossible are also reviewed.

Dajani, J. S.; Bernstein, G. W.

1978-01-01

101

DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS  

Science.gov (United States)

Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

102

Slot Region Radiation Environment Models  

Science.gov (United States)

Herein we present the main characteristics and first results of the Slot Region Radiation Environment Models (SRREMs) project. The statistical models developed in SRREMs aim to address the variability of trapped electron and proton fluxes in the region between the inner and the outer electron radiation belt. The energetic charged particle fluxes in the slot region are highly dynamic and are known to vary by several orders of magnitude on both short and long timescales. During quiet times, the particle fluxes are much lower than those found at the peak of the inner and outer belts and the region is considered benign. During geospace magnetic storms, though, this region can fill with energetic particles as the peak of the outer belt is pushed Earthwards and the fluxes can increase drastically. There has been a renewed interest in the potential operation of commercial satellites in orbits that are at least partially contained within the Slot Region. Hence, there is a need to improve the current radiation belt models, most of which do not model the extreme variability of the slot region and instead provide long-term averages between the better-known low and medium Earth orbits (LEO and MEO). The statistical models developed in the SRREMs project are based on the analysis of a large volume of available data and on the construction of a virtual database of slot region particle fluxes. The analysis that we have followed retains the long-term temporal, spatial and spectral variations in electron and proton fluxes as well as the short-term enhancement events at altitudes and inclinations relevant for satellites in the slot region. A large number of datasets have been used for the construction, evaluation and inter-calibration of the SRREMs virtual dataset. Special emphasis has been given on the use and analysis of ESA Standard Radiation Environment Monitor (SREM) data from the units on-board PROBA-1, INTEGRAL, and GIOVE-B due to the sufficient spatial and long temporal coverage of the slot region. In addition, other datasets such as EI/AZUR, MEA/CRRES, ERMD/XMM also have been considered and processed. The output of the models provides mean and peak energetic particle fluxes for a given mission duration as determined by confidence levels for different time scales. Validation studies and comparison with standard radiation belt models, such as AE8-AP8 have been also performed. The SRREMs project has been commissioned by ESA/ESTEC through contract 4000104839.

Sandberg, Ingmar; Daglis, Ioannis; Heynderickx, Daniel; Evans, Hugh; Nieminen, Petteri

2013-04-01

103

Comparative analysis of different approaches to the computation of long-wave radiation balance of water air systems  

International Nuclear Information System (INIS)

In the present paper, the net long-wave radiation balance of the water-air environmental systems is analysed on the base of several semi-empirical approaches. Various theoretical models of infrared atmospheric radiation are reviewed. Factors, affecting their behavior are considered. Special attention is paid to physical conditions under which those models are applicable. Atmospheric and net infrared radiation fluxes are computed and compared under clear and cloudy sky. Results are presented in graphical form. Conclusions are made on the applicability of models considered for evaluating infrared radiation fluxes in environmental conditions of Central Italy. On the base of present analysis Anderson's model is chosen for future calculations of heat budget of lakes in Central Italy

104

Influence of future air pollution mitigation strategies on total aerosol radiative forcing  

Directory of Open Access Journals (Sweden)

Full Text Available We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030 and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030.

We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to ?2.00 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2 under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by ?1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing could be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extent be controlled by greenhouse gas emissions.

We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations caused by future air pollution mitigation, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time.

S. Kloster

2008-11-01

105

Air pollution model and neural network: an integrated modelling system  

International Nuclear Information System (INIS)

It is well known that neural networks can work as universal approximators of non-linear functions and they have become a useful tool either where any precise phenomenological model is available or when uncertainty complicates the application of deterministic modelling as, for example, in environmental systems. Usually, N N models are using as regression tool. We have developed an integrated modelling system coupling an air dispersion model with a neural network method both to simulate the influence of important parameters on air pollution models and to minimize the input neural net variables. In our approach, an optimised 3-Layer Perception is used to filter the air pollution concentrations evaluated by means of the non-Gaussian analytical model ADMD. We applied this methodology to the well known Indianapolis urban data set which deals with a release of pollutants from an elevated emission source.

106

The radiated fields of focussing air-coupled ultrasonic phased arrays.  

Science.gov (United States)

This paper presents an investigation into the fields radiated into air by ultrasonic phased arrays under transient excitation. In particular, it includes a theoretical prediction of spatial variations in amplitude throughout the both the near-field and far-field of such arrays. The approach has been used to predict the result of phasing to produce a focus in air, which can be seen to be particularly effective in the near-field of the array. Interesting features are observed, which are then described in terms of the performance of both individual elements and the resulting array. It is shown how some elements of design can be used to improve performance in focussing. The predictions are compared to the results of experiments in air using electrostatic arrays, where good focussing could be achieved provided the appropriate design principles were followed. The approach has been developed specifically for use in air, but the results would also hold for modelling in certain medical arrays where a focussing requirement might be needed close to the array itself. PMID:15556653

Neild, A; Hutchins, D A; Robertson, T J; Davis, L A J; Billson, D R

2005-01-01

107

Effects of radiative transfer modelling on the dynamics of a propagating electrical discharge  

OpenAIRE

Abstract A radiative transfer methodology is developed for the modelling of coupled radiation, hydrodynamic and electromagnetic phenomena in unsteady air plasma flows. Absorption spectra are discretized according to the distribution functions of the absorption coefficients resulting from different types of radiative transitions, and this spectral model is combined with the differential P 1 approximation which is shown to predict quite accurately radiative source terms. The study of a propa...

Kahhali, Nicolas; Rivie?re, Philippe; Perrin, Marie-yvonne; Gonnet, Jean-paul; Soufiani, Anouar

2010-01-01

108

Dispersion model maps spread of Fukushima radiation  

Science.gov (United States)

When water flooded the Japanese Fukushima Daiichi nuclear power plant on 11 March 2011, killing power to the plant and destroying its backup generators, the earthquake-triggered disaster resulted in a major nuclear accident, with the plant pouring radioactive material into the air and the water. Research into the effects of the radiation on humans and the environment has been ongoing, but to ensure the accuracy of these aftermath investigations requires understanding the precise concentrations, distribution patterns, and timing of the radionuclide emissions. To provide such an assessment for the marine environment, Estournel et al. used an ocean and atmosphere dispersion model to simulate the movements of radioactive cesium-137 throughout the Japanese coastal waters for 3.5 months following the earthquake.

Schultz, Colin

2013-01-01

109

Modeling of carbon dioxide based air-to-air air conditioners  

OpenAIRE

The world-wide agreement to restrict the use of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has prompted recent research exploring the possibilities of replacement refrigerants, particularly those occurring naturally in the environment. One such natural refrigerant, carbon dioxide, has been considered for certain refrigeration and air conditioning applications. In order to evaluate the potential performance of a refrigeration cycle based on carbon dioxide, a cycle model ha...

Robinson, Douglas Macarthur

2000-01-01

110

Determination of the potential radiation exposure of the population close to the Asse II mine caused by deduction of radioactive substances with the discharge air in the normal operation using the ''Atmospheric Radionuclide-Transport-Model'' (ARTM); Ermittlung der potenziellen Strahlenexposition der Bevoelkerung in der Umgebung der Schachtanlage Asse II infolge Ableitung radioaktiver Stoffe mit den abwettern im bestimmungsgemaessen Betrieb mittels des ''atmospaerischen Radionuklid-Transport-Modells'' ARTM  

Energy Technology Data Exchange (ETDEWEB)

Between 1967 and 1978 125.787 packages filled with low-level and intermediate-level radioactive waste were emplaced in the mining plant Asse II. Volatile radioactive substances like H-3, C-14 and Rn-222 are released from the emplaced waste. These substances reach the ventilated parts of the mine and are released with the discharge air. The potential radiation exposure of the population caused by deduction of radioactive substances with the discharge air in the normal operation is determined by the ''Atmospheric Radionuclide-Transport-Model'' (ARTM). As result the maximal deductions of volatile radioactive substances with the discharge air in the normal operation of the Asse II mine lead to radiation exposure of the population, which is considerably lower than the permissible values of application rate.

Esch, D.; Wittwer, C. [Bundesamt fuer Strahlenschutz, Salzgitter (Germany)

2014-01-20

111

Badminton Projectile Motion: Modeling Air Resistance  

Science.gov (United States)

Badminton Projectile Motion uses the Tracker video analysis tool to analyze the motion of a badminton birdie (or shuttlecock) and then to model the motion to include air resistance. The motion of the birdie is already tracked in the video. Students compare the motion to a model of projectile motion without air resistance and then they modify it to include quadratic drag. The zip file contains the activity handout, two videos and associated Tracker files. The videos included come from the Doane College video library at http://physics.doane.edu/physicsvideolibrary/default.html#projectile and YouTube http://www.youtube.com/watch?v=NzKdQKoNbL To open the Tracker file, download and run Tracker from http://www.cabrillo.edu/~dbrown/tracker/. Tracker is free.

Cox, Anne

2012-06-22

112

Guidance for air sampling at nuclear facilities. [Radiation monitoring  

Energy Technology Data Exchange (ETDEWEB)

The principal uses of air sampling at nuclear facilities are to monitor general levels of radioactive air contamination, identify sources of air contamination, and evaluate the effectiveness of contaminant control equipment, determine exposures of individual workers, and provide automatic warning of hazardous concentrations of radioactivity. These applications of air sampling are discussed with respect to standards of occupational exposure, instrumentation, sample analysis, sampling protocol, and statistical treatment of concentration data. Emphasis is given to the influence of spacial and temporal variations of radionuclide concentration on the location, duration, and frequency of air sampling.

Breslin, A.J.

1976-11-01

113

Standard climate models radiation codes underestimate black carbon radiative forcing  

Directory of Open Access Journals (Sweden)

Full Text Available Radiative forcing (RF of black carbon (BC in the atmosphere is estimated using radiative transfer codes of various complexities. Here we show that the 2-stream radiative transfer codes used most in climate models give too strong forward scattering, leading to enhanced absorption at the surface and too weak absorption by BC. Such calculations are found to underestimate RF by 10% for global mean, all sky conditions, relative to the more sophisticated multi-stream models. The underestimation occurs primarily for low surface albedo, even though BC is more efficient for absorption of solar radiation at high surface albedo.

G. Myhre

2014-10-01

114

Linearized vector radiative transfer model MCC++ for a spherical atmosphere  

International Nuclear Information System (INIS)

Application of radiative transfer models has shown that optical remote sensing requires extra characteristics of radiance field in addition to the radiance intensity itself. Simulation of spectral measurements, analysis of retrieval errors and development of retrieval algorithms are in need of derivatives of radiance with respect to atmospheric constituents under investigation. The presented vector spherical radiative transfer model MCC++ was linearized, which allows the calculation of derivatives of all elements of the Stokes vector with respect to the volume absorption coefficient simultaneously with radiance calculation. The model MCC++ employs Monte Carlo algorithm for radiative transfer simulation and takes into account aerosol and molecular scattering, gas and aerosol absorption, and Lambertian surface albedo. The model treats a spherically symmetrical atmosphere. Relation of the estimated derivatives with other forms of radiance derivatives: the weighting functions used in gas retrieval and the air mass factors used in the DOAS retrieval algorithms, is obtained. Validation of the model against other radiative models is overviewed. The computing time of the intensity for the MCC++ model is about that for radiative models treating sphericity of the atmosphere approximately and is significantly shorter than that for the full spherical models used in the comparisons. The simultaneous calculation of all derivatives (i.e. with respect to absorption in all model atmosh respect to absorption in all model atmosphere layers) and the intensity is only 1.2-2 times longer than the calculation of the intensity only

115

The direct and inverse problems of an air-saturated poroelastic cylinder submitted to acoustic radiation  

Directory of Open Access Journals (Sweden)

Full Text Available A wave-fluid saturated poroelastic structure interaction model based on the modified Biot theory (MBT and plane-wave decomposition using orthogonal cylindrical functions is developed. The model is employed to recover from real data acquired in an anechoic chamber, the poromechanical properties of a soft cellular melamine cylinder submitted to an audible acoustic radiation. The inverse problem of acoustic diffraction is solved by constructing the objective functional given by the total square of the difference between predictions from the MBT interaction model and diffracted field data from experiment. The faculty of retrieval of the intrinsic poromechanical parameters from the diffracted acoustic fields, indicate that a wave initially propagating in a light fluid (air medium, is able to carry in the absence of mechanical excitation of the specimen, information on the macroscopic mechanical properties which depend on the microstructural and intrinsic properties of the solid phase.

Erick Ogam

2011-09-01

116

A mathematical correlation between variations in solar radiation parameters. 2. Global radiation, air temperature and specific humidity  

International Nuclear Information System (INIS)

We derive from first principles, an equation which expresses global radiation as a function of specific humidity and air temperature at screen height. The practical validity of this equation is tested by using humidity, air temperature and global radiation data from Tanzania. It is shown that global radiation values calculated on the basis of the derived equation agree with measured radiation values to within ± 8% as long as the prevalent (horizontal) winds are either calm or light. It is noted that the equation is equally valid at times of strong horizontal winds provided that the temperature and humidity measuring site is sufficiently shielded from the winds. This implies that meteorological stations that are (for some unavoidable reasons) unable to stock pyranometers can still procure reasonable estimates of local global radiation as long as they can, at least, stock the relatively cheaper barometers and wet- and dry-bulb psychrometers. (author). 12 refs, 1 fig., 4 tabs

117

AIR INGRESS ANALYSIS: COMPUTATIONAL FLUID DYNAMIC MODELS  

Energy Technology Data Exchange (ETDEWEB)

The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.

Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang

2010-08-01

118

VALMET-A valley air pollution model  

Energy Technology Data Exchange (ETDEWEB)

Following a thorough analysis of meteorological data obtained from deep valleys of western Colorado, a modular air-pollution model has been developed to simulate the transport and diffusion of pollutants released from an elevated point source in a well-defined mountain valley during the nighttime and morning transition periods. This initial version of the model, named VALMET, operates on a valley cross section at an arbitrary distance down-valley from a continuous point source. The model has been constructed to include parameterizations of the major physical processes that act to disperse pollution during these time periods. The model has not been fully evaluated. Further testing, evaluations, and development of the model are needed. Priorities for further development and testing are provided.

Whiteman, C.D.; Allwine, K.J.

1983-09-01

119

A dispersion modelling system for urban air pollution  

Energy Technology Data Exchange (ETDEWEB)

An Urban Dispersion Modelling system UDM-FMI, developed at the Finnish Meteorological Institute is described in the report. The modelling system includes a multiple source Gaussian plume model and a meteorological pre-processing model. The dispersion model is an integrated urban scale model, taking into account of all source categories (point, line, area and volume sources). It includes a treatment of chemical transformation (for NO{sub 2}) wet and dry deposition (for SO{sub 2}) plume rise, downwash phenomena and dispersion of inert particles. The model allows also for the influence of a finite mixing height. The model structure is mainly based on the state-of-the-art methodology. The system also computes statistical parameters from the time series, which can be compared to air quality guidelines. The relevant meteorological parameters for the dispersion model are evaluated using data produced by a meteorological pre-processor. The model is based mainly on the energy budget method. Results of national investigations have been used for evaluating climate-dependent parameters. The model utilises the synoptic meteorological observations, radiation records and aerological sounding observations. The model results include the hourly time series of the relevant atmospheric turbulence 51 refs.

Karppinen, A.; Kukkonen, J.; Nordlund, G.; Rantakrans, E.; Valkama, I.

1998-10-01

120

Detailed radiative transport modeling of a radiative divertor  

International Nuclear Information System (INIS)

An effective radiative divertor maximizes the utilization of atomic processes to spread out the energy deposition to the divertor chamber walls and to reduce the peak heat flux. Because the mixture of neutral atoms and ions in the divertor can be optically thick to a portion of radiated power, it is necessary to accurately model the magnitude and distribution of line radiation in this complex region. To assess their importance we calculate the effects of radiation transport using CRETIN, a multi-dimensional, non-local thermodynamic equilibrium simulation code that includes the atomic kinetics and radiative transport processes necessary to model the complex environment of a radiative divertor. We also include neutral transport to model radiation from recycling neutral atoms. This paper presents a case study of a high-recycling radiative divertor with a typical large neutral pressure at the divertor plate to estimate the impact of H line radiation on the overall power balance in the divertor region with consideration for line opacities and atomic kinetics. ((orig.))

121

Detailed radiative transport modeling of a radiative divertor  

Energy Technology Data Exchange (ETDEWEB)

An effective radiative divertor maximizes the utilization of atomic processes to spread out the energy deposition to the divertor chamber walls and to reduce the peak heat flux. Because the mixture of neutral atoms and ions in the divertor can be optically thick to a portion of radiated power, it is necessary to accurately model the magnitude and distribution of line radiation in this complex region. To assess their importance we calculate the effects of radiation transport using CRETIN, a multi-dimensional, non-local thermodynamic equilibrium simulation code that includes the atomic kinetics and radiative transport processes necessary to model the complex environment of a radiative divertor. We also include neutral transport to model radiation from recycling neutral atoms. This paper presents a case study of a high-recycling radiative divertor with a typical large neutral pressure at the divertor plate to estimate the impact of H line radiation on the overall power balance in the divertor region with consideration for line opacities and atomic kinetics. ((orig.)).

Wan, A.S. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Dalhed, H.E. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Scott, H.A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Post, D.E. [ITER Joint Central Team, San Diego Co-Center, San Diego, CA 92037 (United States); Rognlien, T.D. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

1995-04-01

122

Detailed radiative transport modeling of a radiative divertor  

Science.gov (United States)

An effective radiative divertor maximizes the utilization of atomic processes to spread out the energy deposition to the divertor chamber walls and to reduce the peak heat flux. Because the mixture of neutral atoms and ions in the divertor can be optically thick to a portion of radiated power, it is necessary to accurately model the magnitude and distribution of line radiation in this complex region. To assess their importance we calculate the effects of radiation transport using CRETIN, a multi-dimensional, non-local thermodynamic equilibrium simulation code that includes the atomic kinetics and radiative transport processes necessary to model to complex environment of a radiative divertor. We also include neutral transport to model radiation from recycling neutral atoms. This paper presents a case study of a high-recycling radiative divertor with a typical large neutral pressure at the divertor plate to estimate the impact of H line radiation on the overall power balance in the divertor region with consideration for line opacities and atomic kinetics.

Wan, A. S.; Dalhed, H. E.; Scott, H. A.; Post, D. E.; Rognlien, T. D.

1995-04-01

123

Combined effects of air temperature, wind, and radiation on the resting metabolism of avian raptors  

International Nuclear Information System (INIS)

American kestrels, Falco sparverius; red-tailed hawks, Buteo jamaicensis; and golden eagles, Aquila chrysaetos, were perched in a wind tunnel and subjected to various combinations of air temperature, wind, and radiation. Oxygen consumption was measured under the various combinations of environmental variables, and multiple regression equations were developed to predict resting metabolism as a function of body mass, air temperature, wind speed, and radiation load

124

PAT-2 (Plutonium Air Transportable Model 2)  

International Nuclear Information System (INIS)

The PAT-2 (Plutonium Air Transportable Model 2) package is designed for the safe transport of plutonium and/or uranium in small quantities, especially as used in international safeguards activities, and especially as transported by air. The PAT-2 package is resistant to severe accidents, including that of a high-speed jet aircraft crash, and is designed to withstand such environments as extreme impact, crushing, puncturing and slashing loads, severe hydrocarbon-fueled fires, and deep underwater immersion, with no escape of contents. The accident environments may be imposed upon the package singly or seqentially. The package meets the requirements of 10 CFR 71 for Fissile Class I packages with a cargo of 15 grams of Pu-239, or other isotopic forms described herein, not to exceed 2 watts of thermal activity. Packaging, operational features, and contents of package, are discussed

125

A simple model for cloud radiative forcing  

OpenAIRE

We present a simple model for the longwave and shortwave cloud radiative forcing based on the evaluation of extensive radiative transfer calculations, covering a global range of conditions. The simplicity of the model equations fosters the understanding on how clouds affect the Earth's energy balance. In comparison with results from a comprehensive radiative transfer model, the accuracy of our parameterization is typically better than 20%. We demonstrate the usefulness of our model using...

Corti, T.; Peter, T.

2009-01-01

126

Air Dispersion Modeling for Building 3026C/D Demolition  

International Nuclear Information System (INIS)

This report presents estimates of dispersion coefficients and effective dose for potential air dispersion scenarios of uncontrolled releases from Oak Ridge National Laboratory (ORNL) buildings 3026C, 3026D, and 3140 prior to or during the demolition of the 3026 Complex. The Environmental Protection Agency (EPA) AERMOD system1-6 was used to compute these estimates. AERMOD stands for AERMIC Model, where AERMIC is the American Meteorological Society-EPA Regulatory Model Improvement Committee. Five source locations (three in building 3026D and one each in building 3026C and the filter house 3140) and associated source characteristics were determined with the customer. In addition, the area of study was determined and building footprints and intake locations of air-handling systems were obtained. In addition to the air intakes, receptor sites consisting of ground level locations on four polar grids (50 m, 100 m, 200 m, and 500 m) and two intersecting lines of points (50 m separation), corresponding to sidewalks along Central Avenue and Fifth Street. Three years of meteorological data (2006 2008) were used each consisting of three datasets: (1) National Weather Service data; (2) upper air data for the Knoxville-Oak Ridge area; and (3) local weather data from Tower C (10 m, 30 m and 100 m) on the ORNL reservation. Annual average air concentration, highest 1 h average and highest 3 h average air concentrations were computed using AERMOD for the five source locations for the tOD for the five source locations for the three years of meteorological data. The highest 1 h average air concentrations were converted to dispersion coefficients to characterize the atmospheric dispersion as the customer was interested in the most significant response and the highest 1 h average data reflects the best time-averaged values available from the AERMOD code. Results are presented in tabular and graphical form. The results for dose were obtained using radionuclide activities for each of the buildings provided by the customer. Radiation dose was calculated assuming complete release of the building inventory as information was lacking regarding the portion of the building inventory expected to be released. Thus the results are derived using an extremely conservative release as documented in the Preliminary Hazard Screening report. To more closely approximate the result of a release, one must estimate the fraction of the total inventory released and multiply the results described above by that fraction. An example of how this calculation is accomplished is provided. Should an actual uncontrolled release occur, the results of this modeling effort could only be used to establish a rough order-of-magnitude for the event.

127

Influence of future air pollution mitigation strategies on total aerosol radiative forcing  

Directory of Open Access Journals (Sweden)

Full Text Available We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030 and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030.

We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to ?2.05 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2 under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by ?1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing cloud be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extend be controlled by greenhouse gas emissions.

We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations in the future within a realistic range, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time.

S. Kloster

2008-03-01

128

Air quality and radiative forcing impacts of anthropogenic volatile organic compound emissions from ten world regions  

Science.gov (United States)

Non-methane volatile organic compounds (NMVOCs) influence air quality and global climate change through their effects on secondary air pollutants and climate forcers. Here we simulate the air quality and radiative forcing (RF) impacts of changes in ozone, methane, and sulfate from halving anthropogenic NMVOC emissions globally and from 10 regions individually, using a global chemical transport model and a standalone radiative transfer model. Halving global NMVOC emissions decreases global annual average tropospheric methane and ozone by 36.6 ppbv and 3.3 Tg, respectively, and surface ozone by 0.67 ppbv. All regional reductions slow the production of peroxyacetyl nitrate (PAN), resulting in regional to intercontinental PAN decreases and regional NOx increases. These NOx increases drive tropospheric ozone increases nearby or downwind of source regions in the Southern Hemisphere (South America, Southeast Asia, Africa, and Australia). Some regions' NMVOC emissions contribute importantly to air pollution in other regions, such as East Asia, the Middle East, and Europe, whose impact on US surface ozone is 43%, 34%, and 34% of North America's impact. Global and regional NMVOC reductions produce widespread negative net RFs (cooling) across both hemispheres from tropospheric ozone and methane decreases, and regional warming and cooling from changes in tropospheric ozone and sulfate (via several oxidation pathways). The 100 yr and 20 yr global warming potentials (GWP100, GWP20) are 2.36 and 5.83 for the global reduction, and 0.079 to 6.05 and -1.13 to 18.9 among the 10 regions. The NMVOC RF and GWP estimates are generally lower than previously modeled estimates, due to the greater NMVOC/NOx emissions ratios simulated, which result in less sensitivity to NMVOC emissions changes and smaller global O3 burden responses, in addition to differences in the representation of NMVOCs and oxidation chemistry among models. Accounting for a fuller set of RF contributions may change the relative magnitude of each region's impacts. The large variability in the RF and GWP of NMVOCs among regions suggest that regionally specific metrics may be necessary to include NMVOCs in multi-gas climate trading schemes.

Fry, M. M.; Schwarzkopf, M. D.; Adelman, Z.; West, J. J.

2014-01-01

129

Air quality and radiative forcing impacts of anthropogenic volatile organic compound emissions from ten world regions  

Directory of Open Access Journals (Sweden)

Full Text Available Non-methane volatile organic compounds (NMVOCs influence air quality and global climate change through their effects on secondary air pollutants and climate forcers. Here we simulate the air quality and radiative forcing (RF impacts of changes in ozone, methane, and sulfate from halving anthropogenic NMVOC emissions globally and from 10 regions individually, using a global chemical transport model and a standalone radiative transfer model. Halving global NMVOC emissions decreases global annual average tropospheric methane and ozone by 36.6 ppbv and 3.3 Tg, respectively, and surface ozone by 0.67 ppbv. All regional reductions slow the production of PAN, resulting in regional to intercontinental PAN decreases and regional NOx increases. These NOx increases drive tropospheric ozone increases nearby or downwind of source regions in the Southern Hemisphere (South America, Southeast Asia, Africa, and Australia. Some regions' NMVOC emissions contribute importantly to air pollution in other regions, such as East Asia, Middle East, and Europe, whose impact on US surface ozone is 43%, 34%, and 34% of North America's impact. Global and regional NMVOC reductions produce widespread negative net RFs (cooling across both hemispheres from tropospheric ozone and methane decreases, and regional warming and cooling from changes in tropospheric ozone and sulfate (via several oxidation pathways. The total global net RF for NMVOCs is estimated as 0.0277 W m?2 (~1.8% of CO2 RF since the preindustrial. The 100 yr and 20 yr global warming potentials (GWP100, GWP20 are 2.36 and 5.83 for the global reduction, and 0.079 to 6.05 and ?1.13 to 18.9 among the 10 regions. The NMVOC RF and GWP estimates are generally lower than previously modeled estimates, due to differences among models in ozone, methane, and sulfate sensitivities, and the climate forcings included in each estimate. Accounting for a~fuller set of RF contributions may change the relative magnitude of each region's impacts. The large variability in the RF and GWP of NMVOCs among regions suggest that regionally-specific metrics may be necessary to include NMVOCs in multi-gas climate trading schemes.

M. M. Fry

2013-08-01

130

Modeling solar radiation at the Earth's surface. Recent advances  

International Nuclear Information System (INIS)

Solar radiation data is important for a wide range of applications, e.g. in engineering, agriculture, health sector, and in many fields of the natural sciences. A few examples showing the diversity of applications may include: architecture and building design e.g. air conditioning and cooling systems; solar heating system design and use; solar power generation; weather and climate prediction models; evaporation and irrigation; calculation of water requirements for crops; monitoring plant growth and disease control; skin cancer research. Solar radiation data must be provided in a variety of forms to suit these applications. The radiation reaching the upper atmosphere of the Earth is a quantity rather constant in time. But the radiation reaching some point on Earth surface is random in nature. The main cause is the fact that various gases within the atmosphere absorb solar radiation at different wavelengths, and clouds and dust also affect it. There are two ways to obtaining solar radiation data at ground level: by measurement and by modelling. The book will facilitate the calculation of solar radiation required by engineers, designers and scientists and, as a result, will increase the access to needed solar radiation data. (orig.)

131

A fitting formula for radiative cooling based on non-local thermodynamic equilibrium population from weakly-ionized air plasma  

International Nuclear Information System (INIS)

A fitting formula for radiative cooling with collisional-radiative population for air plasma flowfield has been developed. Population number densities are calculated from rate equations in order to evaluate the effects of nonequilibrium atomic and molecular processes. Many elementary processes are integrated to be applied to optically-thin plasmas in the number density range of 1012/cm3 ? N ? 1019/cm3 and the temperature range of 300 K ? T ? 40,000 K. Our results of the total radiative emissivity calculated from the collisional-radiative population are fitted in terms of temperature and total number density. To validate the analytic fitting formula, numerical simulation of a laser-induced blast wave propagation with the nonequilibrium radiative cooling is conducted and successfully reproduces the shock and plasma wave front time history observed by experiments. In addition, from the comparison between numerical simulations with the radiation cooling effect based on the fitting formula and those with a gray gas radiation model that assumes local thermodynamic equilibrium, we find that the displacement of the plasma front is slightly different due to the deviation of population probabilities. By using the fitting formula, we can easily and more accurately evaluate the radiative cooling effect without solving detailed collisional-radiative rate equations

132

Effect of electric field on heat transfer performance of automobile radiator at low frontal air velocity  

Energy Technology Data Exchange (ETDEWEB)

The effect of electric field on the performance of automobile radiator is investigated in this work. In this experiment, a louvered fin and flat tube automobile radiator was mounted in a wind tunnel and there was heat exchange between a hot water stream circulating inside the tube and a cold air stream flowing through the external surface. The electric field was supplied on the airside of the heat exchanger and its supply voltage was adjusted from 0kV to 12kV. From the experiment, it was found that the unit with electric field pronounced better heat transfer rate, especially at low frontal velocity of air. The correlations for predicting the air-side heat transfer coefficient of the automobile radiator, with and without electric field, at low frontal air velocity were also developed and the predicted results agreed very well with the experimental data. (author)

Vithayasai, S.; Kiatsiriroat, T. [Department of Mechanical Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand); Nuntaphan, A. [Mae Moh Training Center, Electricity Generating Authority of Thailand, Lampang 52220 (Thailand)

2006-12-15

133

ACREM: A new air crew radiation exposure measuring system  

International Nuclear Information System (INIS)

Cosmic radiation has already been discovered in 1912 by the Austrian Nobel Laureate Victor F. Hess. After Hess up to now numerous measurements of the radiation exposure by cosmic rays in different altitudes have been performed, however, this has not been taken serious in view of radiation protection.Today, with the fast development of modern airplanes, an ever increasing number of civil aircraft is flying in increasing altitudes for considerable time. Members of civil aircrew spending up to 1000 hours per year in cruising altitudes and therefore are subject to significant levels of radiation exposure. In 1990 ICRP published its report ICRP 60 with updated excess cancer risk estimates, which led to significantly higher risk coefficients for some radiation qualities. An increase of the radiation weighting factors for mean energy neutron radiation increases the contribution for the neutron component to the equivalent dose by about 60%, as compared to the earlier values of ICRP26. This higher risk coefficients lead to the recommendation of the ICRP, that cosmic radiation exposure in civil aviation should be taken into account as occupational exposure. Numerous recent exposure measurements at civil airliners in Germany, Sweden, USA, and Russia show exposure levels in the range of 3-10 mSv/year. This is significantly more than the average annual dose of radiation workers (in Austria about 1.5 mSv/year). Up to now no practicable and economic radiation monitoring system for routine application on board exits. A fairly simple and economic approach to a practical, active in-flight dosimeter for the assessment of individual crew exposure is discussed in this paper

134

Session on modeling of radiative transfer processes  

Science.gov (United States)

The session on modeling of radiative transfer processes is reviewed. Six critical issues surfaced in the discussion concerning scale-interactive radiative processes relevent to the mesoscale convective systems (MCS's). These issues are the need to expand basic knowledge of how MCS's influence climate through extensive cloud shields and increased humidity in the upper troposphere; to improve radiation parameterizations used in mesoscale and General Circulation Model (GCM) models; to improve our basic understanding of the influence of radiation on MCS dynamics due to diabatic heating, production of condensate, and vertical and horizontal heat fluxes; to quantify our understanding of radiative impacts of MCS's on the surface and free atmosphere energy budgets; to quantify and identify radiative and microphysical processes important in the evolution of MCS's; and to improve the capability to remotely sense MCS radiative properties from space and ground-based systems.

Flatau, Piotr

1993-01-01

135

Direct radiative effect of the Russian wildfires and its impact on air temperature and atmospheric dynamics during August 2010  

OpenAIRE

In this study, we investigate the shortwave aerosol direct radiative forcing (ADRF) and its feedback on air temperature and atmospheric dynamics during a major fire event that occurred in Russia during August 2010. The methodology is based on an offline coupling between the CHIMERE chemistry-transport and the Weather Research and Forecasting (WRF) models. First, simulations for the period 5–12 August 2010 have been evaluated by using AERONET (AErosol RObotic NETwork) and s...

Pe?re?, J. C.; Bessagnet, B.; Mallet, M.; Waquet, F.; Chiapello, I.; Minvielle, F.; Pont, V.; Menut, L.

2014-01-01

136

Refined weighted sum of gray gases model for air-fuel combustion and its impacts  

DEFF Research Database (Denmark)

Radiation is the principal mode of heat transfer in utility boiler furnaces. Models for radiative properties play a vital role in reliable simulations of utility boilers and simulation-based design and optimization. The weighted sum of gray gases model (WSGGM) is one of the most widely used models in computational fluid dynamics (CFD) simulation of air-fuel combustion processes. It represents a reasonable compromise between an oversimplified gray gas model and a comprehensive approach addressing high-resolution dependency of radiative properties and intensity upon wavelength. The WSGGM coefficients evaluated by Smith et al. for several partial pressures of CO2 and H2O vapor are often used for gas temperatures up to 2400 K, which is supplemented by the coefficient values presented by Coppalle and Vervisch for higher temperatures until 3000 K. This paper refines the air-fuel WSGGM in terms of accuracy, completeness, and implementation and demonstrates the use and impacts of the refined model in CFD simulation of a conventional air-fuel utility boiler. The refined model is found to make a remarkable difference from the existing models in CFD results, when the particle?radiation interaction is negligible and not taken into account (e.g., in gaseous fuel combustion). Comparatively, the impacts of the refined model are greatly compromised under a solid-fuel combustion scenario because of the important role of the particle?radiation interaction. As the conclusion, the refined air-fuel WSGGM is highly recommended for use in CFD simulation of any air-fuel combustion process because of its greater accuracy, completeness, and applicability.

Yin, Chungen

2013-01-01

137

Estimating global solar radiation using artificial neural network and air temperature data in a semi-arid environment  

Energy Technology Data Exchange (ETDEWEB)

Global solar radiation (GSR) data are desirable for many areas of research and applications in various engineering fields. However, GSR is not as readily available as air temperature data. Artificial neural networks (ANNs) are effective tools to model nonlinear systems and require fewer inputs. The objective of this study was to test an artificial neural network (ANN) for estimating the global solar radiation (GSR) as a function of air temperature data in a semi-arid environment. The ANNs (multilayer perceptron type) were trained to estimate GSR as a function of the maximum and minimum air temperature and extraterrestrial radiation. The data used in the network training were obtained from a historical series (1994-2001) of daily climatic data collected in weather station of Ahwaz located in Khuzestan plain in the southwest of Iran. The empirical Hargreaves and Samani equation (HS) is also considered for the comparison. The HS equation calibrated by applying the same data used for neural network training. Two historical series (2002-2003) were utilized to test the network and for comparison between the ANN and calibrated HS method. The study demonstrated that modelling of daily GSR through the use of the ANN technique gave better estimates than the HS equation. RMSE and R{sup 2} for the comparison between observed and estimated GSR for the tested data using the proposed ANN model are 2.534 MJ m{sup -2} day{sup -1} and 0.889 respectively. (author)

Rahimikhoob, Ali [Irrigation and Drainage Engineering Department, College of Abouraihan, University of Tehran (Iran)

2010-09-15

138

Modeling of radiative energy transfer dynamics  

OpenAIRE

A comprehensive model which can predict the Ho3+ 5I7 YAG (Y3Al5O12) manifold luminescence and radiative energy transfer rate among Ho ions for a given concentration and emission path length within the crystal has been developed. Independently, a model was devised to calculate these rates using measured lifetimes as well as calculated radiative and non-radiative lifetimes. The rates of radiative energy transfer were determined from both of these models and found to be in close agreement.

Lazarus, T.; Armagan, G.; Barnes, N.

1994-01-01

139

A numerical model for multigroup radiation hydrodynamics  

CERN Document Server

We present in this paper a multigroup model for radiation hydrodynamics to account for variations of the gas opacity as a function of frequency. The entropy closure model (M1) is applied to multigroup radiation transfer in a radiation hydrodynamics code. In difference from the previous grey model, we are able to reproduce the crucial effects of frequency-variable gas opacities, a situation omnipresent in physics and astrophysics. We also account for the energy exchange between neighbouring groups which is important in flows with strong velocity divergence. These terms were computed using a finite volume method in the frequency domain. The radiative transfer aspect of the method was first tested separately for global consistency (reversion to grey model) and against a well established kinetic model through Marshak wave tests with frequency dependent opacities. Very good agreement between the multigroup M1 and kinetic models was observed in all tests. The successful coupling of the multigroup radiative transfer...

Vaytet, N M H; Dubroca, B; Delahaye, F

2011-01-01

140

Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation  

International Nuclear Information System (INIS)

Purpose: To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Methods: Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300–430 nm range. An electron-multiplication charge-coupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Results: Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r2 = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r2 = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Conclusions: Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments

141

Mutiple simultaneous event model for radiation carcinogenesis  

International Nuclear Information System (INIS)

Theoretical Radiobiology and Risk Estimates includes reports on: Multiple Simultaneous Event Model for Radiation Carcinogenesis; Cancer Risk Estimates and Neutron RBE Based on Human Exposures; A Rationale for Nonlinear Dose Response Functions of Power Greater or Less Than One; and Rationale for One Double Event in Model for Radiation Carcinogenesis

142

Modeling of an air-backed diaphragm in dynamic pressure sensors: Effects of the air cavity  

Science.gov (United States)

As the key structure of most dynamic pressure sensors, a diaphragm backed by an air cavity plays a critical role in the determination of sensor performance metrics. In this paper, we investigate the influence of air cavity length on the sensitivity and bandwidth. A continuum mechanics model neglecting the air viscous effect is first developed to capture the structural-acoustic coupling between a clamped circular diaphragm and a cylindrical backing air cavity. To facilitate sensor design, close-form approximations are obtained to calculate the static sensitivity and the fundamental natural frequency of the air-backed diaphragm. Parametric studies based on this analytical model show that the air cavity can change both the effective mass and the effective stiffness of the diaphragm. One new finding is that the natural frequency of the air-backed diaphragm behaves differently in three different cavity length ranges. In particular, due to the mass effect of the air cavity being dominant, it is shown for the first time that the natural frequency decreases when the cavity length decreases below a critical value in the short cavity range. Furthermore, a finite element method (FEM) model is developed to validate the continuum mechanics model and to study the damping effect of the air cavity. These results provide important design guidelines for dynamic pressure sensors with air-backed diaphragms.

Liu, Haijun; Olson, Douglas A.; Yu, Miao

2014-12-01

143

Comparison and application study on cosmic radiation dose calculation received by air crew  

International Nuclear Information System (INIS)

Objective: To facilitate evaluation on Cosmic radiation dose received by flight crew by developing a convenient and effective measuring method. Methods: In comparison with several commonly used evaluating methods, this research employs CARI-6 software issued by FAA (Federal Aviation Administration) to measure Cosmic radiation dose for flight crew members exposed to. Results: Compared with other methods, CARI-6 is capable of providing reliable calculating results on radiation dose and applicable to all flight crew of different airlines. Conclusion: Cosmic radiation received by flight crew is on the list of occupational radiation. For a smooth running of Standards for controlling exposure to cosmic radiation of air crew, CARI software may be a widely applied tool in radiation close estimation of for flight crew. (authors)

144

Solving vertical transport and chemistry in air pollution models  

International Nuclear Information System (INIS)

For the time integration of stiff transport-chemistry problems from air pollution modelling, standard ODE solvers are not feasible due to the large number of species and the 3D nature. The popular alternative, standard operator splitting, introduces artificial transients for short-lived species. This complicates the chemistry solution, easily causing large errors for such species. In the framework of an operational global air pollution model, we focus on the problem formed by chemistry and vertical transport, which is based on diffusion, cloud-related vertical winds, and wet deposition. Its specific nature leads to full Jacobian matrices, ruling out standard implicit integration. We compare Strang operator splitting with two alternatives: source splitting and an (unsplit) Rosenbrock method with approximate matrix factorization, all having equal computational cost. The comparison is performed with real data. All methods are applied with half-hour time steps, and give good accuracies. Rosenbrock is the most accurate, and source splitting is more accurate than Strang splitting. Splitting errors concentrate in short-lived species sensitive to solar radiation and species with strong emissions and depositions. 30 refs

145

Performance Analysis and Air Flow Optimization of Radiator Using Simulation  

Directory of Open Access Journals (Sweden)

Full Text Available Automotive engine cooling system takes care of excess heat produced during engine operation. It Regulates Engine surface temperature for engine optimum efficiency. Recent advancement in engine for power forced engine cooling system to develop new strategies to improve its radiator performance efficiency. Also to reduce fuel consumption along with controlling engine emission to indicated environmental pollution norms. This paper throws light on parameters optimization flow changes analysis which influences radiator performance along with reviews some of the systematically with new modern approaches to enhance radiator performance analysis with design and numerical analysis of water heating conductivity to transient analysis single sample tube in different copper graded material analysis in flow passing through the water comparing to the better cost effective and material data its analyzed using in ansys 14.5 version.

K.Ganesan*,

2014-10-01

146

A rapid radiative transfer model for reflection of solar radiation  

Science.gov (United States)

A rapid analytical radiative transfer model for reflection of solar radiation in plane-parallel atmospheres is developed based on the Sobolev approach and the delta function transformation technique. A distinct advantage of this model over alternative two-stream solutions is that in addition to yielding the irradiance components, which turn out to be mathematically equivalent to the delta-Eddington approximation, the radiance field can also be expanded in a mathematically consistent fashion. Tests with the model against a more precise multistream discrete ordinate model over a wide range of input parameters demonstrate that the new approximate method typically produces average radiance differences of less than 5%, with worst average differences of approximately 10%-15%. By the same token, the computational speed of the new model is some tens to thousands times faster than that of the more precise model when its stream resolution is set to generate precise calculations.

Xiang, X.; Smith, E. A.; Justus, C. G.

1994-01-01

147

Skill and uncertainty of a regional air quality model ensemble  

OpenAIRE

Recently several regional air quality projects were carried out to support the negotiation under the Clean Air For Europe (CAFE) programme by predicting the impact of emission control policies with an ensemble of models. Within these projects, CITYDELTA and EURODELTA, the fate of air quality at the scale of European cities or that of the European continent was studied using several models. In this article we focus on the results of EURODELTA. The predictive skill of the ensemble of models is ...

Vautard, R.; Schaap, M.; Bergstro?m, R.; Bessagnet, B.; Brandt, J.; Builtjes, P. J. H.; Krol, M. C.

2009-01-01

148

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air  

Science.gov (United States)

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

149

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air  

Energy Technology Data Exchange (ETDEWEB)

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308?nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

Gulati, P., E-mail: pgulati1512@gmail.com [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India); Prakash, R.; Pal, U. N.; Kumar, M. [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Vyas, V. [Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India)

2014-07-07

150

Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air  

International Nuclear Information System (INIS)

A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308?nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

151

Economic Modeling of Compressed Air Energy Storage  

Directory of Open Access Journals (Sweden)

Full Text Available Due to the variable nature of wind resources, the increasing penetration level of wind power will have a significant impact on the operation and planning of the electric power system. Energy storage systems are considered an effective way to compensate for the variability of wind generation. This paper presents a detailed production cost simulation model to evaluate the economic value of compressed air energy storage (CAES in systems with large-scale wind power generation. The co-optimization of energy and ancillary services markets is implemented in order to analyze the impacts of CAES, not only on energy supply, but also on system operating reserves. Both hourly and 5-minute simulations are considered to capture the economic performance of CAES in the day-ahead (DA and real-time (RT markets. The generalized network flow formulation is used to model the characteristics of CAES in detail. The proposed model is applied on a modified IEEE 24-bus reliability test system. The numerical example shows that besides the economic benefits gained through energy arbitrage in the DA market, CAES can also generate significant profits by providing reserves, compensating for wind forecast errors and intra-hour fluctuation, and participating in the RT market.

Rui Bo

2013-04-01

152

Radiation exposure of the crew in commercial air traffic  

International Nuclear Information System (INIS)

The routine radiation exposure of the crews in Yugoslav Airlines (JAT) has been studied and some previous results are presented. The flights of four selected groups of pilots (four aircraft types) have been studied during one year. Annual exposures and dose equivalents are presented. Some additional results and discussions are given. (1 fig., 4 tabs.)

153

Environmental Protection Agency, Office of Air and Radiation  

Science.gov (United States)

... Program Mold and Moisture Radon Smoke-free Homes IAQ Tribal Program Radiation RadTown Emergencies involving radioactive materials Risk assessment ... Division David Rowson, Director Phone: (202) 343-9370 Program Management Office ... of Page Contact Us to ask a question, provide feedback, or ...

154

Impact of street geometry on downward longwave radiation and air temperature in an urban environment  

Energy Technology Data Exchange (ETDEWEB)

A study on urban geometry has been carried out with regard to urban climate in a medium-sized central European city. Thereby the interrelation between the sky view factor (SVF, the portion of visible sky seen by an observer), downward longwave radiation and air temperature was analysed to get a closer look to the interaction of horizon obstructions, thermal radiation from urban surfaces and the urban heat island. Downward longwave flux and air temperature were measured by car traverses through the city of Krefeld, Germany, during clear and calm summer nights in 2003. The traverse included sections with buildings as well as sections with vegetation. Correlation of longwave radiation and SVF was close and negative with a coefficient of determination R{sup 2} = 0.91, but urban heat island intensities (UHI, calculated from air temperature differences) along the route were weakly correlated with the SVF (0.07 {<=} R{sup 2} {<=} 0.39). With buildings, UHI increased with a reduced SVF, but no tendency was found below trees. This was probably a main result from local topographic effects (cold air accumulation). The study indicates that a nocturnal urban heat island on a microscale is not only affected by horizon obstructions, but also by the spatially variable thermal properties of materials. Moreover, advection diminishes site specific air temperature differences even during low winds. On the other hand, longwave radiation strongly depends on geometric factors and can be predicted well with the SVF. (orig.)

Blankenstein, S.; Kuttler, W. [Dept. of Applied Climatology and Landscape Ecology, Univ. of Duisburg-Essen, Essen (Germany)

2004-10-01

155

The Radiation Streaming Calculation for Air Gap of the Shielding Door  

International Nuclear Information System (INIS)

There are many penetrations and the thin air filled clearance gaps in accelerator facility, such as a cable, a cooling water pipe or an air conditioning duct as well as an air gap of between the wall and the shielding door. The estimation of the radiation streaming through these penetrations or the air filled gaps is one of the most difficult parts in shielding design. The Shin's semiempirical formula describing energy-space distributions of neutrons and gamma-rays streaming in ducts or labyrinths is very useful for application to accelerator facility. A streaming calculation code DUCT-III is based on the Shin's formula with the albedo data up to 3GeV. In this paper, the source term was calculated by MCNPX and the radiation streaming through the air gap of between the wall and the shielding door by DUCT-III. The DUCT-III code is based on the Shin's semi-empirical formula. The formula, which describes the direct and albedo components, is derived in generic straight duct geometry. It is expressed by the product of spatial distributions which are represented by twice and eight-time reflected components, and power of an albedo matrix. This formula was then extended to bent ducts. The inflow of radiations to downstream at a corner of multi-bent ducts is formulated with the flux in the upstream leg. Using the obtained inflow current as the source term to downstream, the formula predicts the radiation flux in the downstream leg

156

Study of the UV radiation bactericidal effect on the bacterial air flora in stock breeding premises  

International Nuclear Information System (INIS)

The evidence obtained experimentally showed live-stock breeding premises to be constantly exposed to bacterial contamination (the number of microbial bodies may amount to 406000/per m3). The application of bactericide lamps DPT-2500 makes it possible to reduce within 1 min the number of viable microbial cells to 96.6%. Ultraviolet radiation reduces Escherichia coli per cent to 73.9% within 45 sec. These data formed a basis for using ultraviolet air radiation in live-stock breeding premises with heavy bacterial contamination; as a result, the bacterial air content was drastically reduced

157

Air  

Science.gov (United States)

... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it ... may be affected by high levels of ozone. Air Quality Index (AQI) How do you know if ...

158

Net radiative forcing and air quality responses to regional CO emission reductions  

Directory of Open Access Journals (Sweden)

Full Text Available Carbon monoxide (CO emissions influence global and regional air quality and global climate change by affecting atmospheric oxidants and secondary species. We simulate the influence of halving anthropogenic CO emissions globally and individually from 10 regions on surface and tropospheric ozone, methane, and aerosol concentrations using a global chemical transport model (MOZART-4 for the year 2005. Net radiative forcing (RF is then estimated using the GFDL (Geophysical Fluid Dynamics Laboratory standalone radiative transfer model. We estimate that halving global CO emissions decreases global annual average concentrations of surface ozone by 0.45 ppbv, tropospheric methane by 73 ppbv, and global annual net RF by 36.1 mW m?2, nearly equal to the sum of changes from the 10 regional reductions. Global annual net RF per unit change in emissions and the 100 yr global warming potential (GWP100 are estimated as ?0.124 mW m?2 (Tg CO?1 and 1.34, respectively, for the global CO reduction, and ranging from ?0.115 to ?0.131 mW m?2 (Tg CO?1 and 1.26 to 1.44 across 10 regions, with the greatest sensitivities for regions in the tropics. The net RF distributions show widespread cooling corresponding to the O3 and CH4 decreases, and localized positive and negative net RFs due to changes in aerosols. The strongest annual net RF impacts occur within the tropics (28° S–28° N followed by the northern midlatitudes (28° N–60° N, independent of reduction region, while the greatest changes in surface CO and ozone concentrations occur within the reduction region. Some regional reductions strongly influence the air quality in other regions, such as East Asia, which has an impact on US surface ozone that is 93% of that from North America. Changes in the transport of CO and downwind ozone production clearly exceed the direct export of ozone from each reduction region. The small variation in CO GWPs among world regions suggests that future international climate agreements could adopt a globally uniform metric for CO with little error, or could use different GWPs for each continent. Doing so may increase the incentive to reduce CO through coordinated policies addressing climate and air quality.

M. M. Fry

2013-05-01

159

Net radiative forcing and air quality responses to regional CO emission reductions  

Directory of Open Access Journals (Sweden)

Full Text Available Carbon monoxide (CO emissions influence global and regional air quality and global climate change by affecting atmospheric oxidants and secondary species. We simulate the influence of halving anthropogenic CO emissions globally and individually from 10 regions on surface and tropospheric ozone, methane, and aerosol concentrations using a global chemical transport model (MOZART-4 for the year 2005. Net radiative forcing (RF is then estimated using the GFDL standalone radiative transfer model. We estimate that halving global CO emissions decreases global annual average concentrations of surface ozone by 0.45 ppbv, tropospheric methane by 73 ppbv, and global annual net RF by 36.1 mW m?2, nearly equal to the sum of changes from the 10 regional reductions. Global annual net RF per unit change in emissions and the 100-yr global warming potential (GWP100 are estimated as ?0.124 mW m?2 (Tg CO yr?1?1 and 1.34, respectively, for the global CO reduction, and ranging from ?0.115 to ?0.131 mW m?2 (Tg CO yr?1?1 and 1.26 to 1.44 across 10 regions, with the greatest sensitivities for regions in the tropics. The net RF distributions show widespread cooling corresponding to the O3 and CH4 decreases, and localized positive and negative net RFs due to changes in aerosols. The strongest annual net RF impacts occur within the tropics (28° S–28° N followed by the northern mid-latitudes (28° N–60° N, independent of reduction region, while the greatest changes in surface CO and ozone concentrations occur within the reduction region. Some regional reductions strongly influence the air quality in other regions, such as East Asia, which has an impact on US surface ozone that is 93% of that from North America. Changes in the transport of CO and downwind ozone production clearly exceed the direct export of ozone from each reduction region. The small variation in CO GWPs among world regions suggests that future international climate agreements could adopt a globally uniform metric for CO with little error, or could use different GWPs for each continent. Doing so may increase the incentive to reduce CO through coordinated policies addressing climate and air quality.

M. M. Fry

2012-12-01

160

Economic damages of ozone air pollution to crops using combined air quality and GIS modelling  

OpenAIRE

This study aims at presenting a combined air quality and GIS modelling methodological approach in order to estimate crop damages from photochemical air pollution, depict their spatial resolution and assess the order of magnitude regarding the corresponding economic damages. The analysis is conducted within the Greater Thessaloniki Area, Greece, a Mediterranean territory which is characterised by high levels of photochemical air pollution and considerable agricultural activity. Ozone concentra...

Vlachokostas, Ch; ????????????, ?.; Nastis, S.; Achillas, Ch; Kalogeropoulos, K.; Karmiris, I.; Moussiopoulos, ?.; Chourdakis, E.; Banias, G.; Limperi, N.; ???????, ?.; ????????, ?.; ???????????????, ?.; ?????????, ?.; ?????????????, ?.

2011-01-01

161

Optical Cerenkov radiation from large air showers. Pt. 1  

International Nuclear Information System (INIS)

New measurements of the lateral distribution of the Cerenkov light in large showers have been made using an array of light detectors at the Haverah Park air shower experiment. Details are presented for the average lateral distribution of the light at core distances 100-600 m in showers initiated by primaries of energy 5 x 1016-1018 eV and incident in the range of zenith 0-350. Measurements have also been made of the curvature of the light front in showers. (orig.)

162

Transport worker radiation exposures handling air shipments of radioactive materials  

International Nuclear Information System (INIS)

Due to the continuing increase in the use of radioactive materials in nuclear medicine and industry there has been a corresponding rise in radioactive material (ram) package shipments via air carriers. Utilizing sensitive thermoluminescent dosimeters which were worn for 6-8 week periods annual transport worker dose estimates were made at several locations within New York State. The estimated doses as a function of transport index on the package label were as follows: freight forwarder servicing New York City Airports handled 31,000 TI units/y and 15 persons wore badges with whole body badge readings: 0.24, 0.60, 0.76, 0.78, 0.83, 0.99 and 1.69 rem/y; for a population dose of 0.36 man-rem/y, ring badges with positive results, 0.71, 1.03 and 1.11 rem/y; 5 air carriers at Buffalo Airport handled 5800 TJ units/y and 41 persons were monitored with 13 positive results: 2 at 0.24, 3 at 0.30, 0.25, 0.31, 2 at 0.37, 0.42, 0.48, 0.60, and 1.55 rem/y for a population dose of 0.14 man-rem/y, ring badge positive results: 0.24 and 6.01 rem/y; 4 freight forwarders at Buffalo Airport handled 3800 TI units/y and 52 persons were monitored with 3 positive results: 0.30, 0.36 and 0.67 rem/y for a population dose fo 0.201 man-rem/y, ring badge positive results: 0.31 and 0.42 rem/y; 4 air carriers and 3 freight forwarders at Rochester Airport handled 170 TI units/y and 19 persons wore badges and none gave an exposure above minimum detectable during monitored period. The annual population d monitored period. The annual population dose per TI were as follows: for New York City freight forwarder, 0.000012 man-rem/TI-y; for Buffalo Airport air carriers, 0.000024 man-rem/TI-y; for Buffalo Airport freight forwarder, 0.0000055 man-rem/TI-y

163

The dynamic radiation environment assimilation model (DREAM)  

International Nuclear Information System (INIS)

The Dynamic Radiation Environment Assimilation Model (DREAM) is a 3-year effort sponsored by the US Department of Energy to provide global, retrospective, or real-time specification of the natural and potential nuclear radiation environments. The DREAM model uses Kalman filtering techniques that combine the strengths of new physical models of the radiation belts with electron observations from long-term satellite systems such as GPS and geosynchronous systems. DREAM includes a physics model for the production and long-term evolution of artificial radiation belts from high altitude nuclear explosions. DREAM has been validated against satellites in arbitrary orbits and consistently produces more accurate results than existing models. Tools for user-specific applications and graphical displays are in beta testing and a real-time version of DREAM has been in continuous operation since November 2009.

164

Updating Ontario's air dispersion models : a discussion paper  

International Nuclear Information System (INIS)

This paper described air dispersion models and technical information relating to Ontario Regulation 346 under the Environmental Protection Act. The Ontario Ministry of the Environment plans to phase out existing air dispersion models and replace them with a series of models from the United States Environmental Protection Agency (in particular AERMOD and ISC-PRIME). However, before adopting the widespread use of the new models in Ontario, the Ministry is undergoing consultation with stakeholders. The Ministry's most recent initiatives in the development of better air quality standards have included the use of the latest scientific information to develop protective, effects-based air standards and the development of a risk management framework to implement the new standards while allowing for time, technology and economic issues to be considered. An update of Regulation 346 air dispersion models ensures that the latest scientific tools are being used to asses compliance with air standards. This will promote the use of the most modern scientific tools available to assess compliance with air quality standards. The major advantage of introducing new air dispersion models is the ability to use effects-based standards with appropriate averaging times to assess compliance. This makes it possible to better assess the health and environmental impacts from air emissions. 3 tabs., 3 figs

165

Evaluation of solar radiation and its application for photovoltaic/thermal air collector for Indian composite climate  

Energy Technology Data Exchange (ETDEWEB)

In this paper, an attempt has been made to evaluate cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi, India by considering the hourly data of global and diffuse radiation obtained for (i) the city region, experimentally observed and (ii) the flat land region obtained from the Department of Indian Meteorology, Pune. Cloudiness/haziness factor for the two models have been determined using simple regression analysis for clear sky condition for New Delhi. The comparison between the cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi for both the models and regions have been made. It has been observed that the cloudiness/haziness and atmospheric transmittance factors obtained by both models gave fair agreement within an accuracy of 0.57%. It has also been observed that there is a significant effect of region on beam and diffuse radiation due to cloudiness/haziness factors as expected. Further the data of solar radiation obtained from the Department of Indian Meteorology, Pune, have been used to evaluate the monthly performance of photovoltaic thermal (PV/T) air collector. It has been found that an overall thermal efficiency and exergy efficiency of PV/T air collector were about 50 and 14%, respectively. (Author)

Joshi, Anand S.; Tiwari, G.N. [Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-11 00 16, (India)

2006-12-06

166

Assessing solar radiation models using multiple variables over Turkey  

Energy Technology Data Exchange (ETDEWEB)

Solar radiation drives many environmental processes; however, needs to be estimated indirectly from more commonly measured meteorological variables since these data are not readily available from most climate stations. A geo-referenced dataset from 159 climate stations of 17 variables (maximum possible sunshine duration, mean, minimum and maximum air temperature, soil temperature, mean and maximum relative humidity, precipitation, cloudiness, evapotranspiration, extraterrestrial radiation, day length, declination angle, day of the year, latitude, longitude, and altitude) was used to model spatio-temporal dynamics of solar radiation over Turkey. A total of 78 empirical models of different mathematical functions with a different combination of 17 explanatory variables were compared based on the error statistics of the Jackknifing validation. The empirical models had adjusted coefficient of determination (R{sub adj} {sup 2}) values of 22.7-96.5% based on the parameterization dataset (P < 0.05). Models 46 and 22.2 provided the most robust performance and were identified as generic models for the estimation of monthly changes in solar radiation over topographically complex terrain of the entire Turkey as a function of maximum possible sunshine hours, extraterrestrial solar radiation, mean temperature, and precipitation. The quadratic and cubic models performed best in terms of the error statistics (P > 0.05), while the performance of the hybrid models was worse than that of the linear, quadratic and cubic models in terms of maximum relative percentage error (e) (P < 0.01). In comparing the interpolation methods of inverse distance weighting and universal co-kriging, anisotropic spherical semi-variogram model of universal co-kriging was found to provide the best description of spatial autocorrelation and variability latent in these data based on the spatial leave-one-out cross-validation. (orig.)

Evrendilek, Fatih [Abant Izzet Baysal University, Department of Environmental Engineering, Bolu (Turkey); Ertekin, Can [Akdeniz University, Department of Farm Machinery, Faculty of Agriculture, Antalya (Turkey)

2008-08-15

167

Radiação solar estimada com base na temperatura do ar para três regiões de Minas Gerais Estimation of solar radiation by air temperature models for three regions of Minas Gerais  

Directory of Open Access Journals (Sweden)

Full Text Available A radiação solar incidente (Rs é uma variável importante em estudos agrícolas, particularmente para a estimativa da evapotranspiração e em modelos para produtividade. Entretanto, sua medição não é, em geral, realizada em estações meteorológicas convencionais. O objetivo deste trabalho foi avaliar nove modelos empíricos de estimativa de Rs, a partir da temperatura, para as regiões Metropolitana, Vale do Rio Doce e Zona da Mata em Minas Gerais. Dados de Rs diários foram obtidos por estações meteorológicas automáticas instaladas nessas regiões e pertencentes ao Instituto Nacional de Meteorologia (INMET. Para todos os modelos foram gerados coeficientes locais de calibração. O desempenho de cada método foi avaliado através dos seguintes indicadores: coeficiente de determinação (R², raiz quadrada do quadrado médio do erro (RQME, erro médio (EM e teste t. A pequena diferença entre os modelos avaliados indica que qualquer um desses modelos é passível de utilização mas, dado à simplicidade, desempenho e significância, o modelo de Hargreaves, calibrado e com dois coeficientes, é o mais aplicável para estimar a radiação solar incidente.The incident solar radiation (Rs is an important variable in agricultural studies, particularly for the estimation of evapotranspiration and yield models. However, its measurement is not commonly performed in conventional meteorological stations. The aim of this study was to evaluate nine empirical models to estimate Rs from the temperature for the Metropolitan, Vale do Rio Doce and Zona da Mata areas in Minas Gerais State, Brazil. The models used were Hargreaves, Annandale, Chen, Bristow & Campbell, Donatelli & Campbell and Hunt. Data used were obtained by Rs daily automatic weather stations installed in these regions and belonging to Instituto Nacional de Meteorologia (INMET. For all models local calibration coefficients were derived. The performance of each method was evaluated using the following statistical indicators: coefficient of determination (R², root mean square error (RMSE, mean bias error (MBE and test-t. The little difference between the models evaluated suggests that any of these models may be used. However, given the simplicity, performance and significance, the model of Hargreaves, calibrated and with two coefficients, is the most suitable for estimating incident solar radiation.

Cláudio R. da Silva

2012-01-01

168

An Analytical Air Pollution Model with Time Dependent Eddy Diffusivity  

OpenAIRE

Air pollution transport and dispersion in the atmospheric boundary layer are modeled by the advection-diffusion equation, that is, essentially, a statement of conservation of the suspended material in an incompressible flow. Many models simulating air pollution dispersion are based upon the solution (numerical or an...

Tiziano Tirabassi; Marco Túllio Vilhena; Daniela Buske; Gervásio Annes Degrazia

2013-01-01

169

Atmospheric Modelling for Air Quality Study over the complex Himalayas  

Science.gov (United States)

An Atmospheric Modelling System has been set up at International Centre for Integrated Mountain Development (ICIMOD) for the assessment of Air Quality across the Himalaya mountain ranges. The Weather Research and Forecasting (WRF) model version 3.5 has been implemented over the regional domain, stretching across 4995 x 4455 km2 centred at Ichhyakamana , the ICIMOD newly setting-up mountain-peak station (1860 m) in central Nepal, and covering terrains from sea-level to the Everest (8848 m). Simulation is carried out for the winter time period, i.e. December 2012 to February 2013, when there was an intensive field campaign SusKat, where at least 7 super stations were collecting meteorology and chemical parameters on various sites. The very complex terrain requires a high horizontal resolution (1 × 1 km2), which is achieved by nesting the domain of interest, e.g. Kathmandu Valley, into 3 coarser ones (27, 9, 3 km resolution). Model validation is performed against the field data as well as satellite data, and the challenge of capturing the necessary atmospheric processes is discussed, before moving forward with the fully coupled chemistry module (WRF-Chem), having local and regional emission databases as input. The effort aims at finding a better understanding of the atmospheric processes and air quality impact on the mountain population, as well as the impact of the long-range transport, particularly of Black Carbon aerosol deposition, to the radiative budget over the Himalayan glaciers. The higher rate of snowcap melting, and shrinkage of permafrost as noticed by glaciologists is a concern. Better prediction will supply crucial information to form the proper mitigation and adaptation strategies for saving people lives across the Himalayas in the changing climate.

Surapipith, Vanisa; Panday, Arnico; Mukherji, Aditi; Banmali Pradhan, Bidya; Blumer, Sandro

2014-05-01

170

High-efficiency particulate air (HEPA) filter performance following service and radiation exposure  

International Nuclear Information System (INIS)

Small HEPA filters were exposed to a 60Co source with a radiation strength of 3 x 107 rads per hour and then exposed to steam--air mixtures at several times filter design flow, followed by extended exposure to steam and air at reduced flow. Additional filters were exposed to air flow in a reactor confinement system and then similarly tested with steam--air mixture flows. The test data and calculated effects of filter pluggage with moisture on confinement system performance following potential reactor accidents are described. Gamma radiation exposure impaired the performance of new filters only slightly and temporarily improved performance of service aged filters. Normal confinement system service significantly impaired filter performance although not sufficiently to prevent adequate performance of the SRP confinement system following an unlikely reactor accident. Calculations based on measured filter pluggage indicate that during an accident air flow could be reduced approximately 50 percent with service-degraded HEPA filters present, or approximately 10 percent with new filters damaged by the radiation exposure. (U.S.)

171

ATTENUATION OF SOLAR UV RADIATION BY AEROSOLS DURING AIR POLLUTION EPISODES  

Science.gov (United States)

Increase in the amount of solar UV radiation reaching the surface due to decrease in stratospheric ozone continues to be a major concern (WMO, 1998). However, recent studies show that absorption and smattering by aerosols during air pollution episode decreases the amount of radi...

172

A new polarized atmospheric radiative transfer model  

Science.gov (United States)

A plane-parallel polarized radiative transfer model is described. The model is used to compute the radiance exiting a vertically inhomogeneous atmosphere containing randomly-oriented particles. Both solar and thermal sources of radiation are considered. A direct method of incorporating the polarized scattering information is combined with the doubling and adding method to produce a relatively simple formulation. Several numerical results are presented for verification and comparison.

Evans, K. F.; Stephens, G. L.

1991-01-01

173

INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING  

Science.gov (United States)

Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

174

Comparative analysis of different approaches to the computation of long-wave radiation balance of water air systems  

Energy Technology Data Exchange (ETDEWEB)

In the present paper, the net long-wave radiation balance of the water-air environmental systems is analysed on the base of several semi-empirical approaches. Various theoretical models of infrared atmospheric radiation are reviewed. Factors, affecting their behavior are considered. Special attention is paid to physical conditions under which those models are applicable. Atmospheric and net infrared radiation fluxes are computed and compared under clear and cloudy sky. Results are presented in graphical form. Conclusions are made on the applicability of models considered for evaluating infrared radiation fluxes in environmental conditions of Central Italy. On the base of present analysis Anderson's model is chosen for future calculations of heat budget of lakes in Central Italy. [Italian] Nel presente rapporto viene analizzato il bilancio della radiazione infrarossa per i sistemi acquatici sulla base di alcune formule semi-empiriche. Vengono esaminati vari modelli della radiazione infrarossa atmosferica e i fattori che la influenzano. I flussi di radiazione infrarossa dall'atmosfera in condizioni di cielo sereno e nuvoloso vengono calcolati e confrontati. L'analisi dell'applicabilita' dei modelli considerati per il calcolo dei flussi di radiazione infrarossa in corrispondenza delle condizioni ambientali dell'Italia centrale suggerisce di scegliere il modello di Anderson per la valutazione del bilancio calorico die laghi vulcanici.

Zhukovsii, K.; Nourani, Y.; Monte, L. [ENEA, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy). Dipt. Energia

1999-07-01

175

Handbook of anatomical models for radiation dosimetry  

CERN Document Server

Covering the history of human model development, this title presents the major anatomical and physical models that have been developed for human body radiation protection, diagnostic imaging, and nuclear medicine therapy. It explores how these models have evolved and the role that modern technologies have played in this development.

Eckerman, Keith F

2010-01-01

176

To the exposure of air crew members to cosmic radiation  

International Nuclear Information System (INIS)

According to an ICRP recommendation, the exposure of jet aircraft crew to radiation should be considered as occupational exposure when the annual equivalent doses are liable to exceed 1 mSv. Many new data on this type of exposure collected since 1991 are presented and analyzed. The dose equivalent rates established are fitted as a function of flight altitude. An analysis of data from cosmic ray monitors has shown that the presence of cosmic rays in the Earth's atmosphere is rather stable since early 1992. An estimation was therefore made of the possible influence of the solar cycle phase by means of a transport code. The results obtained are compared with experimental data

177

On mathematical modelling of cell radiation inactivation  

International Nuclear Information System (INIS)

The analysis was made of the compatibility of several mathematical models for radiation inactivation of mammalian cells with a large number of experimental data and some statistical correlation were revealed between the model survival curve an the approximated experimental dependence. It was shown that the statistical agreement between some model and some set of the experimental data was not a sufficient condition for the theoretical significance of the model. For the most plausible model to be reliably defined by the statistical criteria experimental data should be obtained on many millions of similar biological objects. So one of the theoretical models for radiation inactivation of cells was chosen to give the best description of the known variety of data on mammalian cell inactivation by different types of radiation

178

Simulating aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe haze conditions in winter  

Directory of Open Access Journals (Sweden)

Full Text Available The aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe winter haze conditions during January~2013 are simulated using the fully coupled on-line Weather Research and Forecasting/Chemistry (WRF-Chem model. Three simulation scenarios including different aerosol configurations are undertaken to distinguish the impact of aerosol radiative (direct and semi-direct and indirect effects on meteorological variables and air quality. Simulated spatial and temporal variations of PM2.5 are generally consistent with surface observations, with a mean bias of ?18.9 ?g m?3 (?15.0% averaged over 71 big cities in China. Comparisons between different scenarios reveal that aerosol radiative effects (direct effect and semi-direct effects result in reductions of downward shortwave flux at the surface, 2 m temperature, 10 m wind speed and planetary boundary layer (PBL height by up to 84.0 W m?2, 3.2 °C, 0.8 m s?1, and 268 m, respectively. The simulated impact of the aerosol indirect effects is comparatively smaller. Through reducing the PBL height and wind speeds, the aerosol effects lead to increases in surface concentrations of primary pollutants (CO and SO2 and PM2.5. The aerosol feedbacks on secondary pollutants such as surface ozone and PM2.5 mass concentrations show some spatial variations. Surface O3 mixing ratio is reduced by up to 6.9 ppb due to reduced incoming solar radiation and lower temperature. Comparisons of model results with observations show that inclusion of aerosol feedbacks in the model significantly improves model's performances in simulating meteorological variables and improves simulations of PM2.5 temporal distributions over the North China Plain, the Yangtze River Delta, the Pearl River Delta, and Central China. Although the aerosol–radiation–cloud feedbacks on aerosol mass concentrations are subject to uncertainties, this work demonstrates the significance of aerosol–radiation–cloud feedbacks for real-time air quality forecasting under haze conditions.

B. Zhang

2014-10-01

179

Air shower simulations with the new hadronic interaction model EPOS  

International Nuclear Information System (INIS)

Interpretation of EAS experiments results is strongly based on air shower simulations. The latter being based on hadronic interaction models, any new model can help for the understanding of the nature of cosmic rays. The new model EPOS reproducing all major results of existing accelerator data (including detailed data of RHIC experiments) has been introduced in air shower simulation programs CORSIKA and CONEX allowing comparison with former models such as QGSJET01 or SIBYLL. New results for air shower observables will be discussed in detail. (orig.)

180

Integrated air quality modelling for a designated air quality management area in Glasgow  

Energy Technology Data Exchange (ETDEWEB)

Currently, most local authorities in the UK use well-established Gaussian-type dispersion models to predict the air quality in urban areas. The use of computational fluid dynamics (CFD) in integrated urban air quality modelling is still in its infancy, despite having an enormous potential in assessing and improving natural ventilation in built-up areas. This study assesses the suitability of a general CFD code (PHOENICS) for use in integrated urban air quality modelling for regulatory purposes. An urban air quality model of a designated air quality management area in the city centre of Glasgow has been developed by integrating traffic flow data for urban road networks, traffic pollutant emission data and a three-dimensional CFD dispersion model of a complex configuration of street canyons. The results are in good agreement with field measurements taken during the continuous monitoring campaign, and show that a general CFD code has indeed the potential for regulatory use. Although this numerical tool has demonstrated satisfactory performance, it is observed that small differences in monitoring station positioning may yield significant variations of the measured mean concentration, due to large values of horizontal and vertical local concentration gradients. Although, at this stage, the accuracy of the developed Glasgow urban air quality model is highly dependent on the experience of its users, it is believed that use of a CFD code (such as PHOENICS) could benefit urban planners, architects, HVAC engineers and all other professionals interested in public health. (author)

Mumovic, D. [University College London, London (United Kingdom). The Bartlett School of Graduate Studies; Crowther, J.M. [Glasgow Caledonian University, Glasgow (United Kingdom). School of the Built and Natural Environment; Stevanovic, Z. [Institute of Nuclear Sciences Vinca, University of Belgrade, Belgrade (Yugoslavia)

2006-12-15

181

Influences of atmospheric conditions and air mass on the ratio of ultraviolet to total solar radiation  

Energy Technology Data Exchange (ETDEWEB)

The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major atmospheric variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with atmospheric conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the atmospheric effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.

Riordan, C.J.; Hulstrom, R.L.; Myers, D.R.

1990-08-01

182

Decoupled predictions of radiative heating in air using a particle simulation method  

Science.gov (United States)

A particle simulation technique with decoupled radiation is used to estimate the radiative emission along the stagnation streamline and the radiative heating at the stagnation point of a blunt-nosed vehicle entering the earth's atmosphere at hypersonic speed. The direct simulation Monte Carlo (DSMC) method is used to compute the fluid mechanics of the weakly ionized flow. The radiative emission is computed using the NEQAIR computer code with the radiation decoupled from the flowfield solution. It is concluded that the new models make it possible to decrease the predicted total radiative heating at the stagnation point of the vehicle by a factor of 15. A comparison of the DSMC approach with a continuum flow model shows that the total predicted radiative heating estimates agree within a factor of 2.

Boyd, Iain D.; Whiting, Ellis E.

1992-01-01

183

MODELED MESOSCALE METEOROLOGICAL FIELDS WITH FOUR-DIMENSIONAL DATA ASSIMILATION IN REGIONAL SCALE AIR QUALITY MODELS  

Science.gov (United States)

This paper addresses the need to increase the temporal and spatial resolution of meteorological data currently used in air quality simulation models, AQSMs. ransport and diffusion parameters including mixing heights and stability used in regulatory air quality dispersion models a...

184

Assessment of diffuse radiation models in Azores  

Science.gov (United States)

Measured irradiance databases usually consist of global solar radiation data with limited spatial coverage. Hence, solar radiation models have been developed to estimate the diffuse fraction from the measured global irradiation. This information is critical for the assessment of the potential of solar energy technologies; for example, the decision to use photovoltaic systems with tracking system. The different solar radiation models for this purpose differ on the parameters used as input. The simplest, and most common, are models which use global radiation information only. More sophisticated models require meteorological parameters such as information from clouds, atmospheric turbidity, temperature or precipitable water content. Most of these models comprise correlations with the clearness index, kt (portion of horizontal extra-terrestrial radiation reaching the Earth's surface) to obtain the diffuse fraction kd (portion of diffuse component from global radiation). The applicability of these different models is related to the local atmospheric conditions and its climatic characteristics. The models are not of general validity and can only be applicable to locations where the albedo of the surrounding terrain and the atmospheric contamination by dust are not significantly different from those where the corresponding methods were developed. Thus, models of diffuse fraction exhibit a relevant degree of location dependence: e.g. models developed considering data acquired in Europe are mainly linked to Northern, Central or, more recently, Mediterranean areas. The Azores Archipelago, with its particular climate and cloud cover characteristics, different from mainland Europe, has not yet been considered for the development of testing of such models. The Azorean climate reveals large amounts of cloud cover in its annual cycle, with spatial and temporal variabilities more complex than the common Summer/Winter pattern. This study explores the applicability of different existing correlation models of diffuse fraction and clearness index or other plain parameters to the Azorean region. Reliable data provided by the Atmospheric Radiation Measurements (ARM) Climate Research Facility from the Graciosa Island deployment of the ARM Mobile Facility (http://www.arm.gov/sites/amf/grw) was used to perform the analysis. Model results showed a tendency to underestimate higher values of diffuse radiation. From the performance results of the correlation models reviewed it was clear that there is room for improvement.

Magarreiro, Clarisse; Brito, Miguel; Soares, Pedro; Azevedo, Eduardo

2014-05-01

185

Air core Bragg fibers for delivery of near-infrared laser radiation  

Science.gov (United States)

Optical fibers designed for high power laser radiation delivery represent important tools in medicine, solar systems, or industry. For such purposes several different types of glass optical fibers such as silica, sapphire, or chalcogenide ones as well as hollow-glass fibers, photonic crystal fibers and Bragg fibers have been investigated. Air-core Bragg fibers or photonic crystal fibers offer us the possibility of light transmission in a low dispersive material - air having a high damage threshold and small non-linear coefficient. However, preforms for drawing Bragg fibers can be fabricated by MCVD method similarly as preforms of standard silica fibers. In this paper we present fundamental characteristics of laboratory-designed and fabricated Bragg fibers with air cores intended for delivery of laser radiation at a wavelength range from 0.9 to 1.5 ?m. Bragg fibers with different air core diameters of 5, 45 and 73 mm were prepared. The fiber core was surrounded by three pairs of circular Bragg layers. Each pair was composed of one layer with a high and one layer with a low refractive index with a contrast up to 0.03. Several laser sources emitting at 0.975, 1.06, and 1.55 ?m were used as radiation sources. Attenuation coefficients, overall transmissions, bending losses, and spatial profiles of output beams from fibers were determined at these wavelengths. The lowest attenuation coefficient of 70 dB/km was determined for the 45 ?m and 73 mm air-core fiber when radiation from a laser was launched into the fibers by using optical lenses. However, multimodal transmission has been observed in such condition. It has also been found that bending losses of such fibers are negligible for bending diameters higher than 15 mm.

Jelínek, Michal; Frank, Milan; Kube?ek, Václav; Mat?jec, Vlastimil; Kašík, Ivan; Podrazký, Ond?ej

2014-12-01

186

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

Science.gov (United States)

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

187

Radioactive contamination monitoring of air and emergency response, procedure of the radiation protection section  

International Nuclear Information System (INIS)

Full text: The Radiation Protection Section has planned procedures in place in the event of an emergency dealing with loose radioactive material. During the clean-up, radiation dose must be monitored. Air sampling is important. It can be used during a radiological emergency to estimate committed dose from inhaled radioactive dusts. Radioactive material concentration, in Bq/m3, obtained from air sampling is converted to committed dose by using an appropriate dose conversion factor, in units of Sv/Bq, in International Atomic Energy Agency's basic safety series number 115 called International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources. A single dose conversion factor will be used for uranium and thorium series, in the field to estimate committed dose without the need for an extensive calculation. During an emergency, operations will be busy and hectic and using an approximate number for this will be much easier to deal with. This will give an idea of exposure level and the risk associated with this exposure. The procedure may also be used to estimate committed dose during spillage of any radioactive material. An air sampling procedure will be discussed during the presentation. Other procedures will be included for an emergency response situation.

188

ROLE OF MODELS IN AIR QUALITY MANAGEMENT DECISIONS  

Science.gov (United States)

Within the frame of the US-India bilateral agreement on environmental cooperation, a team of US scientists have been helping India in designing emission control policies to address urban air quality problems. This presentation discusses how air quality models need to be used for ...

189

Gelation of a radiation crosslinked model polyethylene  

International Nuclear Information System (INIS)

A radiation crosslinked model linear low-density polyethylene (LLDPE) exhibits power-law relaxation, G(t)=St-n at its gel point (GP). The relaxation exponent has a value of about 0.46. The relaxation behavior is dominated by power laws, not only directly at GP, but in a very broad vicinity of GP and in a frequency window, which narrows with distance from the gel point. The power law exponent decreases with increasing radiation dose (increasing extent of crosslinking). Independent measurements of the gel fraction and the molecular-weight distribution of the radiated samples' soluble fraction support the rheological observations. (orig.)

190

Dark radiation confronting LHC in Z? models  

International Nuclear Information System (INIS)

Recent cosmological data favour additional relativistic degrees of freedom beyond the three active neutrinos and photons, often referred to as “dark radiation”. Extensions of the SM involving TeV-scale Z? gauge bosons generically contain superweakly interacting light right-handed neutrinos which can constitute this dark radiation. In this Letter we confront the requirement on the parameters of the E6Z? models to account for the present evidence of dark radiation with the already existing constraints from searches for new neutral gauge bosons at LHC7

191

Cancer risk models for ionizing radiation.  

OpenAIRE

Risk estimation in radiation carcinogenesis depends primarily on epidemiological data and hazard rate models. The A-bomb survivors follow-up provides information on the complexity of this process. Several hazard rate models are briefly discussed and illustrated using the A-bomb experience.

Hoel, D. G.

1987-01-01

192

FUZZY MODELLING OF LIQUID DESICCANT BASED AIR DEHUMIDIFICATION SYSTEM  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the Mamdani fuzzy models of heat exchanger and dehumidifier (absorber of an air dehumidification process occurring in a packed bed using liquid desiccant. Temperature of water used ascooling medium at the inlet of heat exchanger, temperature of desiccant solution(from the regenerator ,inlet air humidity ratio of humid air, flow rate per unit cross-sectional area, temperature of desiccant solution(from the heat exchanger have been taken as different variables for packed bed using liquid desiccant .Mamdani Fuzzy model is developed using the above mentioned variables to predict the water condensation rate from the air to the desiccant solution in terms of known operating parameters. The model predictions were compared against a reliable set of experimental data available in the literature and respective mathematical models for their validation. Integrated fuzzy model was also developed forliquid desiccant system

Harpreet Singh,

2011-04-01

193

RRTM: A rapid radiative transfer model  

Energy Technology Data Exchange (ETDEWEB)

A rapid radiative transfer model (RRTM) for the calculation of longwave clear-sky fluxes and cooling rates has been developed. The model, which uses the correlated-k method, is both accurate and computationally fast. The foundation for RRTM is the line-by-line radiative transfer model (LBLRTM) from which the relevant k-distributions are obtained. LBLRTM, which has been extensively validated against spectral observations e.g., the high-resolution sounder and the Atmospheric Emitted Radiance Interferometer, is used to validate the flux and cooling rate results from RRTM. Validations of RRTM`s results have been performed for the tropical, midlatitude summer, and midlatitude winter atmospheres, as well as for the four Intercomparison of Radiation Codes in Climate Models (ICRCCM) cases from the Spectral Radiance Experiment (SPECTRE). Details of some of these validations are presented below. RRTM has the identical atmospheric input module as LBLRTM, facilitating intercomparisons with LBLRTM and application of the model at the Atmospheric Radiation Measurement Cloud and Radiation Testbed sites.

Mlawer, E.J.; Taubman, S.J.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)

1996-04-01

194

Air gamma radiation background measured by the method for continuous monitoring  

International Nuclear Information System (INIS)

More than 200000 computer proceeded results from measuring the air dose rate of gamma radiation are presented. It is established that the annual air dose rate values for the past 3 years differ from each other no more than 4.54% General conclusions about the proved advantages and opportunities unfolding the use of this method, as well as future plans concerning future routine monitoring are mentioned. It is also shown the reason for this method being recommended for total ecological investigation on the connection of the natural gamma background with the climate and other physical factors of the environment, including their change and mutual influence

195

Multiple ARMAX modeling scheme for forecasting air conditioning system performance  

International Nuclear Information System (INIS)

System identification is a procedure to characterize the dynamic behavior of a system, subsystem or individual component from measured data. This paper presents a study on the modeling and parameter identification of air conditioning processes by using the mathematical black box modeling technique, autoregressive moving average exogeneous (ARMAX) structure. A generic multiple input multiple output (MIMO) ARMAX structure of typical air conditioning systems is developed, whose parameters are identified by using the recursive extended least squares (RELS) method. The performance of the model is compared with that of a single input single output (SISO) ARMAX model. A significant component of the determination of an ARMAX model is the selection of an appropriate model order. Models of different orders and the effects of properties are evaluated. Site measurements from an air conditioning system in a building are used for the testing and validation of the models in the study

196

Development and evaluation of Vehicular Air Pollution Inventory model  

Science.gov (United States)

Estimating emissions by road traffic is a key-issue for air pollution management in many regions. Emission models are important tools to help compute vehicular exhausts. There are several vehicular emission models available worldwide, though most of them have been developed in countries with advanced economies. Due to substantial differences in conditions and available datasets, application of these models in developing countries like India might be misleading. To bridge the gap between the available models and the tools needed in developing countries, the Vehicular Air Pollution emission Inventory (VAPI) model has been developed and evaluated. The proposed VAPI model is based on a simple approach incorporating emission factors and correction factors. This model can be used for estimating emissions for exhaust, evaporative and non-exhaust conditions in Indian cities. The temporal trend of emission estimates calculated with the VAPI model show reasonable agreement with ambient air concentrations monitored at locations significantly influenced by vehicular activity.

Nagpure, Ajay Singh; Gurjar, B. R.

2012-11-01

197

Radiation transfer model intercomparison (RAMI) exercise  

Science.gov (United States)

The community involved in modeling radiation transfer over terrestrial surfaces designed and implemented the first phase of a radiation transfer model intercomparison (RAMI) exercise. This paper discusses the rationale and motivation for this endeavor, presents the intercomparison protocol as well as the evaluation procedures, and describes the principal results. Participants were asked to simulate the transfer of radiation for a variety of precisely defined terrestrial environments and illumination conditions. These were abstractions of typical terrestrial systems and included both homogeneous and heterogeneous scenes. The differences between the results generated by eight different models, including both one-dimensional and three-dimensional approaches, were then documented and analyzed. RAMI proposed a protocol to quantitatively assess the consequences of the model discrepancies with respect to application, such as those motivating the development of physically based inversion procedures. This first phase of model intercomparison has already proved useful in assessing the ability of the modeling community to generate similar radiation fields despite the large panoply of models that were tested. A detailed analysis of the results also permitted to identify apparent "outliers" and their main deficiencies. Future undertakings in this intercomparison framework must be oriented toward an expansion of RAMI into other and more complex geophysical systems as well as the focusing on actual inverse problems.

Pinty, Bernard; Gobron, Nadine; Widlowski, Jean-Luc; Gerstl, Sigfried A. W.; Verstraete, Michel M.; Antunes, Mauro; Bacour, CéDric; Gascon, Ferran; Gastellu, Jean-Philippe; Goel, Narendra; Jacquemoud, StéPhane; North, Peter; Qin, Wenhan; Thompson, Richard

2001-06-01

198

Improving the marketing abilities of some egyptian exports using radiation technology in cairo air port  

International Nuclear Information System (INIS)

The economics of establishing a food irradiation facility at cairo airport are discussed together with the effect of various parameters on uint processing costs. This study comprises the determination of the commodity mix for the egyptian food commodities that are proposed for irradiation and export from the cairo airport. The commodity mix is distributed for the full utilization of the working capacity and the evaluation of the type of the irradiation facility and also the radiation source strength. The financial analysis for such an irradiation facility is also carried out. It provides a model for calculating specific unit processing costs by correlating known capital costs with annual operation cost and annual throughputs. We analyzed the cost- benefit of the proposed food irradiation facility. We took into account the cost of the capital investment, operation and other additional parameters and then estimated the unit cost. The investment criteria utilized for commercial evaluation were internal rate of return (I.I.R.) and pay back period (P.B.P.). The irradiation cost and the additional income are also discussed. The results of this analysis showed that the installation of the an irradiation unit for the establishment of food irradiation unit in cairo air port in would be economically feasible

199

Optical, radio and x-ray radiation of red sprites produced by runaway air breakdown  

International Nuclear Information System (INIS)

The authors use the runaway air breakdown model of upward discharges to calculate optical, radio, and X-ray radiation generated by red sprites. Red sprites are high altitude (up to 90 km) lightning discharges. Aircraft based observations show that sprites are predominantly red in color at altitudes above ?55 km with faint blue tendrils, which extend downward to an altitude of 40 km; the duration of a single sprite is less than 17 ms, their maximum brightness is about 600 kR, and estimated total optical energy is about 1--5 kJ per event. The ground based observations show similar results, and provide some additional information on spatial and temporal structure of sprites, and on sprite locations. One difference between aircraft and ground-based observations is that blue tendrils are rarely observed from the ground. Sprites usually occur above the anvils of large mesoscale convective systems and correlate with strong positive cloud to ground discharge. Upward discharges are the most probable source of X-ray emission observed above large thunderstorm complexes by the Compton Gamma-ray Observatory. To escape the atmosphere these ?-rays must originate above 25 km altitude. Red sprites are usually observed at altitudes higher than 50 km, and are therefore a likely source of this x-ray emission

200

Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification.  

Science.gov (United States)

In recent years, the application of titanium dioxide (TiO?) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO? on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO? solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency. PMID:24699867

Asadi, Somayeh; Hassan, Marwa; Nadiri, Ataallah; Dylla, Heather

2014-07-01

201

The air radiation dose unit investigation method in the village of Iitate  

International Nuclear Information System (INIS)

Radioactive contamination caused by the nuclear accident were to release large amounts of radioactive material by the Tohoku-Pacific Ocean Earthquake, the Kanto region are ranging widely not only in the Northeast as well as the surrounding area. I am currently work is proceeding decontamination countries and local governments have been made in the same uniform survey Soil Contamination Countermeasures Act without investigating the detailed distribution of the radioactive material. Radioactive material because it is spread by geological agency, the distribution varies depending on the topographical and geological conditions. Determination of air radiation dose is measured at a height of 1 m above the ground. Air radiation dose measurement is important in order to reveal the distribution of radioactive material in a wide area in the measure of radioactive materials. If fact, measured in the area that is contaminated with high concentrations of radioactive material, with the result that the height measured at the earth surface and 1 m it was very different. Measurements of the surface earth to clarify the presence of radioactive material in more detail, is higher than the measured value detected by the high 1 m. It is considered to have been influenced by the surface geology, vegetation, and microtopography, radiation dose space has measure radiation dose space from all directions, the radiation dose space on the surface of the earth radioactive piled up on the ground considered because it is dominated by the material shall be measured on the ground surface shows the distribution of radioactive material from Contamination survey radioactive material in a wide range, cheap, fast is important, and reproducible method of investigation and a field type. It is important to note that, to check whether the radioactive material has been moved to a depth below the ground surface which is a paramount concern measures radioactive contamination. Method of measuring space radiation dose survey team conducted Fukushima has adopted a method of measuring while shielding such as lead, while digging in the ground surface and space dosimetry of land surface and a height of 1 m above ground. As for this investigation method, the measurement relatively analyzes air radiation dose while being affected by the outskirts as the air radiation dose unit investigation method by the investigation method according to the geo-stratigraphic unit investigation method. (author)

202

Convective-radiative interaction in a parallel plate channel - Application to air-operated solar collectors  

Science.gov (United States)

An analysis is made for simultaneously developing laminar velocity and temperature fields in a parallel plate channel in which convective and radiative heat transfer interact. One wall of the channel is externally heated and the other is externally insulated; air is the heat transfer fluid. These conditions are similar to those in an air-operated flat-plate solar collector. The results show that the radiant interchange causes the task of convective heating of the fluid to be shared between the two walls, with as much as 40% of the convective transfer taking place at the externally adiabatic wall. This can give rise to a significant reduction of the temperature of the directly heated wall which, for a solar collector, tends to improve its efficiency. The Nusselt numbers in the presence of radiation are higher than those for pure forced convection.

Liu, C. H.; Sparrow, E. M.

1980-08-01

203

Modelling of the Through-air Bonding Process  

OpenAIRE

A computational fluid dynamics (CFD) modelling ofthe through-air bonding process of nonwoven fabricproduction is reported in this article. In the throughairprocess, hot air is passed through the fibrous webto heat and melt polymer fibers. Molten polymersubsequently flows to the point of contact betweenany two fibers to produce a bond. Two differentmodelling strategies are adapted to produce acomprehensive understanding of the through-airbonding process. In macroscale modelling, a CFDmodel is ...

Hossain, M.; M Acar, Ph D.; Malalasekera, W.

2009-01-01

204

Validation of a novel air toxic risk model with air monitoring.  

Science.gov (United States)

Three modeling systems were used to estimate human health risks from air pollution: two versions of MNRiskS (for Minnesota Risk Screening), and the USEPA National Air Toxics Assessment (NATA). MNRiskS is a unique cumulative risk modeling system used to assess risks from multiple air toxics, sources, and pathways on a local to a state-wide scale. In addition, ambient outdoor air monitoring data were available for estimation of risks and comparison with the modeled estimates of air concentrations. Highest air concentrations and estimated risks were generally found in the Minneapolis-St. Paul metropolitan area and lowest risks in undeveloped rural areas. Emissions from mobile and area (nonpoint) sources created greater estimated risks than emissions from point sources. Highest cancer risks were via ingestion pathway exposures to dioxins and related compounds. Diesel particles, acrolein, and formaldehyde created the highest estimated inhalation health impacts. Model-estimated air concentrations were generally highest for NATA and lowest for the AERMOD version of MNRiskS. This validation study showed reasonable agreement between available measurements and model predictions, although results varied among pollutants, and predictions were often lower than measurements. The results increased confidence in identifying pollutants, pathways, geographic areas, sources, and receptors of potential concern, and thus provide a basis for informing pollution reduction strategies and focusing efforts on specific pollutants (diesel particles, acrolein, and formaldehyde), geographic areas (urban centers), and source categories (nonpoint sources). The results heighten concerns about risks from food chain exposures to dioxins and PAHs. Risk estimates were sensitive to variations in methodologies for treating emissions, dispersion, deposition, exposure, and toxicity. PMID:21651597

Pratt, Gregory C; Dymond, Mary; Ellickson, Kristie; Thé, Jesse

2012-01-01

205

VALMET: a valley air pollution model. Final report. Revision 1  

Energy Technology Data Exchange (ETDEWEB)

An air quality model is described for predicting air pollution concentrations in deep mountain valleys arising from nocturnal down-valley transport and diffusion of an elevated pollutant plume, and the fumigation of the plume on the valley floor and sidewalls after sunrise. Included is a technical description of the model, a discussion of the model's applications, the required model inputs, sample calculations and model outputs, and a full listing of the FORTRAN computer program. 55 refs., 27 figs., 6 tabs.

Whiteman, C.D.; Allwine, K.J.

1985-04-01

206

Technical Note: The air quality modeling system Polyphemus  

Directory of Open Access Journals (Sweden)

Full Text Available Polyphemus is an air quality modeling platform which aims at covering the scope and the abilities of modern air quality systems. It deals with applications from local scale to continental scale, using two Gaussian models and two Eulerian models. It manages passive tracers, radioactive decay, photochemistry and aerosol dynamics. The structure of the system includes four independent levels with data management, physical parameterizations, numerical solvers and high-level methods such as data assimilation. This enables sensitivity and uncertainty analysis, primarily through multimodel approaches. On top of the models, drivers implement advanced methods such as model coupling or data assimilation.

V. Mallet

2007-10-01

207

Technical Note: The air quality modeling system Polyphemus  

Directory of Open Access Journals (Sweden)

Full Text Available Polyphemus is an air quality modeling platform which aims at covering the scope and the abilities of modern air quality systems. It deals with applications from local scale to continental scale, using two Gaussian models and two Eulerian models. It manages passive tracers, radioactive decay, photochemistry and aerosol dynamics. The structure of the system includes four independent levels with data management, physical parameterizations, numerical solvers and high-level methods such as data assimilation. This enables sensitivity and uncertainty analysis, primarily through multimodel approaches. On top of the models, drivers implement advanced methods such as model coupling or data assimilation.

V. Mallet

2007-05-01

208

Measurement of Cherenkov radiation pulse shape of extensive air showers in the TUNKA experiment  

International Nuclear Information System (INIS)

The optical detector and the recording system are developed for studying the shape of Cherenkov light pulses from extensive air showers (EAS) in the TUNKA experiment. The optical detector is based on fast photomultipliers. The recording system consists of optical fibers, fast analog-to-digital converter, pulse discriminator, delay circuits and logic synchronizing module. The pulse of EAS Cherenkov radiation obtained by means of this setup on the distance ? 300 m for the shower axis is presented

209

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

International Nuclear Information System (INIS)

Primary standard of unities air kerma and air kerma rate X-ray and gamma radiation, placed at VNIIM, consists of: plate-parallel free-air ionization chamber IK 10-60 for low-energy X-ray in the generating potential range from 10 to 50 kV; plate-parallel free-air ionization chamber IK 50-400 for medium-energy X-ray in the generating potential range from 50 to 300 kV; cavity cylindrical graphite chambers C1 and C30 with volumes 1 cm3 and 30 cm3 for reproduction and transmission the dimensions gamma radiation unities using Cs-137 and Co-60 sources. The next irradiation facilities are used at VNIIM: in low-energy X-ray range: a constant-potential high-voltage generator and a tungsten-anode Xray tube with inherent filtration of around 1 mm Be; in medium-energy X-ray range: set on the basis of an industrial X-ray apparatus Isovolt-400 and a tungsten-anode X-ray tube with inherent filtration of around 3,5 mm Al; in gamma radiations field: units with a radioactive sources Cs-137 with activity 140 and 1200 GBq and Co-60 with activity 120 GBq and irradiation set with a source from Co-60 (activity 3200 GBq). The last one belongs to Central Research Institute for Radiology and Roentgenology (CNIRRI). For measuring currents and charges of standard chambers we use electrometers such as Keithley of model 6517A and B7-45 manufactured by 'Belvar' (Republic Belarus). The reference radiation qualities L, N, H series according to ISO 4037 and the radiation qualities RQR, RQA and RQF according to IEC 61267 for calibration and verification of the therapeutic, diagnostic measurement means are realized in the low-energy and medium-energy X-ray standards. The VNIIM air kerma primary standard of has been participated in the international comparisons: key comparison BIPM.R1(I)-K1 for gamma radiation of Co-60 in 1997; supplementary comparisons BIPM.R1(I)-S10 for gamma radiation of Cs-137 in 1997; key comparison BIPM.R1(I)-K2 for low-energy X-ray range in 1998; key comparison BIPM.R1(I)-K3 for medium-energy X-ray range in 1998. The results of comparisons are presented in the table 1. Dimensions of unities of air kerma and air kerma rate are transmitted from primary standard to secondary standards with expanded uncertainty from 1,3 to 2,5 % (k=2), which are including and at laboratory SSDL/VNIIM and base dosimetry laboratory CNIRRI. The comparisons of secondary standards with the primary standard VNIIM are performed one time in 5 years. The laboratory SSDL/VNIIM is the component of state primary standards laboratory in the field of measurement ionizing radiations VNIIM. SSDL/VNIIM has the secondary standard - universal dosimeter UNIDOS with ionization chambers of volume from 0,6 cm3 to 10 liters, radioactive sources from Fe-55, Cd-109, Am-241, Cs-137 and Co-60 with activity from 0,03 to 140 GBq. The primary standard equipment and facility on the basis industrial X-ray apparatus YRD-1 with a tungsten-anode X-ray tube and inherent filtration of around 3 mm Al (at generating potential from 50 to 250 kV) are used for calibration dosimetric devices in the field X-ray. There is termoluminescence dosimetric system such as KDT-02M with TL detectors from LiF for spending audit measurements by method 'dose-post'. Laboratory SSDL/VNIIM and base dosimetric laboratory CNIRRI are carried out calibrations and verifications of air kerma and air kerma rate reference standards and working measurement means for X-ray and gamma therapy and diagnostics, belonging to the oncology and diagnostic centers, clinics and hospitals. The laboratory CNIRRI fulfils the verification of measurement means and supervision of the application in the medical radiology, but the regional departments of radial diagnostics put into practice monitoring of doses, obtained by patients and staff at fulfilling of diagnostic and medical procedures. The diagnostic and clinical dosimeters are calibrated directly under the primary standard of air kerma and air kerma rate for achievement the highest accuracy. At 2000-2001 this calibrations were carried out for the Belarusian Research Institute of Oncol

210

Air-crew exposure to cosmic radiation on board of Polish passenger aircraft  

International Nuclear Information System (INIS)

To establish the need for individual monitoring of air crew, exposure of air-crew members of Polish airlines - LOT to cosmic radiation has been determined and several dosimetry methods tested in flight. Passive radiation dosimetry (using thermoluminescent LiF and chemically etched CR-39 detectors) Was supported by calculations with the CARI computer code. We found that the air crew of most of the LOT aircraft studied (with exception of those flying ATR propeller aircraft) may somewhat exceed or, in certain conditions (depending on solar activity), may considerably exceed the effective dose level if 1 mSv per year. For crew members flying regularly on B-767 aircraft, the estimated yearly effective dose ranged between 2 mSv and and 5 mSv, depending mainly on flying frequency and solar activity. During periods of enhanced intensity of cosmic radiation (i.e. during minimum solar activity) the effective dose could be close to the level of 6 mSv per year. (author)

211

The Solar Radiation Physical Modeling Project  

Science.gov (United States)

The Solar Radiation Physical Modeling (SRPM) project is a computing system for quantitative evaluation of physical processes modeling in the context of high spectral resolution solar observations. The forward-computation modular design is based on a set of components that permit the researcher to compute the high-resolution spectrum of the solar atmosphere at any wavelength based on given physical processes and parameters. The SRPM object-oriented design allows for either internally computing or using externally generated parameters (e.g., atmospheric models, level populations, etc.) and computing very detailed radiative losses and emitted spectrum. The computed data and the input atomic data are stored in relations databases that are accessed via SQL. The atomic data is often updated with the latest from NIST, TOPBASE, CHIANTI, etc. Current modules include: H and other elements NLTE with PRD calculations, computation of coronal loop footpoints transition region energy balance and H particle diffusion, and computation of the entire solar spectrum for 1-dimensional models with either LTE or provided ionization and level populations. A set of semi-empirical 1-dimensional models is being developed for quiet and active solar features to fit much of the observed spectra. New modules and algorithms under construction are 3-dimensional NLTE radiative transfer for chromospheric and prominence applications, convection-diffusion equation for studying flows and particle diffusion in coronal loops and their footpoints, and MHD simulation coupled with the NLTE radiative-transfer.

Fontenla, J.; Dasgupta, S.

2005-12-01

212

Model of gas-discharge radiation detector  

International Nuclear Information System (INIS)

The invention is referred to technical physics and can be used for simulation of the work of gas-discharge ?-and ?-radiation detector. The model of physical phenomena and devices in which the liquid drop charging is used when it falls on the charged surface is very close to the suggested one. The aim of the invention is to ensure the model adequacy and to provide a posssibility of separate demonstration of the process of ?-and ?-radiation detection. It is achieved by the fact that the cathode of a detector model is made in the form of metal, perforated plate with funnel-like holes, it is connected with negative potential of voltage source. The anode is made in the form of metal plate with positive potential of voltage source. The source of drops is fixed above cathode and galvanometer is brought into the circuit. To simulate, the process of ?-radiation detection the source of drops is filled with soapy water, i.e. made in the form of soap bubble source. In the model suggested invisible processes occurring in gas-discharge detector during ionizing radiation detection are adequately modelled by visual transformations with drops and soap bubbles

213

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

International Nuclear Information System (INIS)

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

214

A radiative transfer model for surface radiation budget studies  

Science.gov (United States)

A high resolution spectral radiative transfer model of the troposphere for computing downwelling radiance and flux density at the surface in the 5-200 micron region has been developed. The model is fast and accurate and takes into consideration all major and minor constituents active in this region, namely, water vapor, carbon dioxide, ozone, nitrous oxide, and methane. It uses the quasi-random band model of absorption for computing atmospheric transmittances due to various bands. Continuum absorption by water vapor in the 8-14 micron region has also been taken into account. The model has been used to examine the sensitivity of downwelling flux to variations of surface water vapor pressure (or surface relative humidity), water vapor scale-height and concentrations of other gaseous constituents of the atmosphere. In addition, sensitivity to changes in a number of cloud parameters, namely, fractional cloud cover, cloud height, and high-cloud emissivity, has also been examined. Results obtained with the present model compare well with those from the empirical and semi-empirical correlations. The present work demonstrates, for the first time, the feasibility of using a high-resolution narrow-band model for computing this flux for a meteorological application.

Gupta, S. K.

1983-01-01

215

Radiation exposure of the aircrew and passengers on some Czechoslovak air lines  

International Nuclear Information System (INIS)

According to the ICRP 60 recommendation, the aircrew should be included among workers whose exposure to cosmic radiation is considered to be occupational exposure. This brings about the need for a more precise determination and the mapping of the exposure level on different air routes. The results are presented of measurements performed by the staff of the Institute of Radiation Dosimetry on board of CSA aircraft (TU 154 M and A 310-300 Airbus) in 1991-1992. A number of passive and active devices were used to measure the ionizing and neutron component of cosmic radiation. The results obtained confirm the basic ideas about the influence of various factors on the exposure level. The interpretation of data is discussed in detail, particularly with respect to its possible modification based on new data on particle spectra on board of subsonic civil transport aircraft. (author) 2 tabs., 4 figs., 24 refs

216

Status of Galileo interim radiation electron model  

Science.gov (United States)

Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EDP) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii.

Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.

2003-01-01

217

Radiation enhanced conduction in insulators: computer modelling  

International Nuclear Information System (INIS)

The report describes the implementation of the Klaffky-Rose-Goland-Dienes [Phys. Rev. B.21 3610,1980] model of radiation-enhanced conduction and describes the codes used. The approach is demonstrated for the data for alumina of Pells, Buckley, Hill and Murphy [AERE R.11715, 1985]. (author)

218

Some analytical models of radiating collapsing spheres  

OpenAIRE

We present some analytical solutions to the Einstein equations, describing radiating collapsing spheres in the diffusion approximation. Solutions allow for modeling physical reasonable situations. The temperature is calculated for each solution, using a hyperbolic transport equation, which permits to exhibit the influence of relaxational effects on the dynamics of the system.

Herrera, L.; Di Prisco, A.; Ospino, J.

2006-01-01

219

Computer models for optimizing radiation therapy  

International Nuclear Information System (INIS)

The aim of this contribution is to outline how methods of system analysis, control therapy and modelling can be applied to simulate normal and malignant cell growth and to optimize cancer treatment as for instance radiation therapy. Based on biological observations and cell kinetic data, several types of models have been developed describing the growth of tumor spheroids and the cell renewal of normal tissue. The irradiation model is represented by the so-called linear-quadratic model describing the survival fraction as a function of the dose. Based thereon, numerous simulation runs for different treatment schemes can be performed. Thus, it is possible to study the radiation effect on tumor and normal tissue separately. Finally, this method enables a computer-assisted recommendation for an optimal patient-specific treatment schedule prior to clinical therapy. (orig.)

220

Radiative effects in induction plasma modeling  

International Nuclear Information System (INIS)

While it is generally accepted that in small scale discharges plasmas can be treated as optically thin, there has been a wide discrepancy regarding the relative importance given to radiative energy transfer in induction plasma modelling. Radiative energy loss from an induction plasma has been neglected in most 1-D theoretical analysis. More recent work involving the 2-D modelling of the flow and temperature fields in an induction plasma treated radiative energy losses as a volumetric heat sink. The results show that 30-40% of the energy dissipated in the plasma can be lost as radiation. In the present study, a comparative analysis is made between available literature data on volumetric emission of an argon plasma at atmospheric pressure and their effect on the computed temperature fields. The role of radiative energy transfer from the plasma is noted to be particularly important in the presence of small concentrations of metal vapors which are known to increase considerably the volumetric emission of the plasma. Typical results given show the corresponding integral emission from pure argon plasma and an argon plasma in the presence of copper vapor resulting from the injection of 1 g/min of copper powder in the discharge

221

Sensitivity analysis of health risk assessments air quality modeling  

International Nuclear Information System (INIS)

The use of a health risk assessment (HRA) as a decision making tool has increased dramatically over the last few years. As such, the science and methodology that is required to complete a HRA has taken on a greater level of refinement. The completion of a HRA requires many different disciplines including process engineering, source and ambient air testing, meteorology, air quality modeling, chemistry and toxicology. Each one of these disciplines will have an impact on the final results of an HRA. As a brief overview, an HRA can be separated into the following major area of analysis: Estimates of the chemicals that are emitted and their associated emission rates; Air emission source characteristics, i.e., stack height, stack gas temperature, etc.; Physical setting of the area surrounding the source; Analysis of the local meteorology;Analysis of the downwind atmospheric dispersion; The population characteristics in the surrounding area; Environmental fate of the emitted chemical(s) and population exposure;and Analysis of health risk. Each of these areas will effect the final results. The purpose of the article is to address some of the impacts that an air quality modeling analysis can have on the final HRA results. The relative impacts of the air quality modeling results will be shown by completing a sensitivity analysis of various modeling parameters that are commonly encountered when evaluating the downwind air quality impacts for an HRA. Specifically, the authors eva for an HRA. Specifically, the authors evaluate the sensitivity of an HRA air quality modeling analysis to the following parameters: Screening level model analysis versus actual one-year model simulations; Atmospheric deposition rate; and Aerodynamic surface roughness

222

A comparison of model predictions and observations of the transfer of 137Cs through the air-pasture-cow-milk pathway  

International Nuclear Information System (INIS)

Environmental measurements following the Chernobyl accident for selected locations in the United States and Europe were compared with model predictions of the transfer of 137Cs through the air-pasture-cow-milk pathway. The models include IAEA Safety Series No. 57, AIRDOS/EPA, NRC Regulatory Guides 1.109 and 1.111, the National Council on Radiation Protection and Measurements (NCRP) screening model, and the PATHWAY dynamic food-chain model. Time integrals of the 137Cs concentrations in air, pasture, and milk were estimated, and the predicted and observed grass/air, milk/air, and milk/grass concentration ratios were compared. (author)

223

75 FR 56487 - Airworthiness Directives; Erickson Air-Crane Incorporated Model S-64F Helicopters  

Science.gov (United States)

...2120-AA64 Airworthiness Directives; Erickson Air-Crane Incorporated Model S-64F Helicopters AGENCY...airworthiness directive (AD) for Erickson Air-Crane Incorporated (Erickson Air-Crane) Model S- 64F helicopters. The AD would...

2010-09-16

224

76 FR 66617 - Airworthiness Directives; Erickson Air-Crane Incorporated Model S-64F Helicopters  

Science.gov (United States)

...2120-AA64 Airworthiness Directives; Erickson Air-Crane Incorporated Model S-64F Helicopters AGENCY: Federal...airworthiness directive (AD) for the Erickson Air-Crane (Erickson Air-Crane) Model S-64F helicopters. The amendment...

2011-10-27

225

Analysis of spatial distribution of Cherenkov radiation of extensive air showers detected by a Samarkand state university device  

International Nuclear Information System (INIS)

Investigations of spatial distribution functions (SDF) of the Cherenkov radiation of extensive air showers (EAS) are carried out. The results of the SDF calculation of the Cherenkov radiation are presented for two variants of the scaling model differing by the assumption on the character of growth of hadron inelastic interaction cross section with energy. Calculations are performed for purely proton composition of primary particles. In the first model the cross section increases according to the law: tau=tau0 (1+0.03 ln (E/100)), but in the second model it increases according to the law tau=tau0 (1+0.014 ln2 (E/100)) (E is energy in GeV). At small distances from the shower axis (100 m) the SDF is shown to be sensitive to the model calculation technique. It is anticipated from the data obtained that the variant of the second model gives higher location of maximum and is in better agreement with experimental data

226

Air-Ice Interactions Associated with a Storm Process in a 2-Dimentional Coupled Model  

Science.gov (United States)

The SHEBA deployment was carried out for an entire year from October 1997 to October 1998 and captured an outstanding warm air advection event in the middle of May 1998, when a well-developed cyclonic system moved slowly northward from the Bering Sea and the Gulf of Alaska. The Beaufort Sea was covered by the advection of warm air mass from east to west during a period from 10th through 12th May. We employed a 2-dimentional high resolution coupled atmospheric boundary layer (ABL) and sea-ice thermodynamics model to investigate the air-ice interactions during this period. The model domain was configured in the dominant direction of the prevailing winds and extended 420km downwind from the SHEBA Camp with a horizontal resolution of 5 km. The ABL had 50 levels from surface up to 3 km, while the snow and the sea-ice had 10 vertical layers, respectively, in the model. The ABL inflow boundary condition was updated every hour based on the SHEBA rawinsounding data. The ABL and the sea-ice models were spun up to a quasi-equilibrium in which the modeled surface temperature was close to the AVHRR retrieval skin temperature. During the three-day simulation, the model apparently captured the warm air advection well. The modeled spatial distribution of surface temperatures were close to the AVHRR derived values. An increase of temperature occured in the snow and upper sea-ice layer, in response to the penetration of solar radiation and invasion of warm air mass into the model domain. The former factor predominantes, while the latter amplifies the effects of the former. Heat accumulates in the snow layer, a response in part to the increasing solar radiation during this transition season. Due to the increases of air moisture carried by the advection, condensation occurs. The diurnal amplitude of the low-level air temperature and the snow/ice temperature is damped in the simulation. Parallel simulation in an uncoupled model provided insight into the feedback produced by the coupling.

Cheng, B.; Zhang, X.; Vihma, T.; Walsh, J. E.

2005-12-01

227

Parameterization of a simple model to estimate monthly global solar radiation based on meteorological variables, and evaluation of existing solar radiation models for Tabouk, Saudi Arabia  

International Nuclear Information System (INIS)

Using 9 years of solar radiation data, we established a simple model to calculate the monthly mean global solar radiation on a horizontal surface in Tabouk (28.38 deg. N, 36.6 deg. E, Saudi Arabia). The model correlates the global solar radiation with five meteorological parameters. These parameters are the perceptible water vapor, air temperature, relative humidity, atmospheric pressure, and the mean monthly daily fraction of possible sunshine hours. The estimated global radiation from the model was compared with the measured values using the mean bias error (MBE), coefficient of correlation (R), root mean square error (RMSE), and mean percentage error (MPE). The t statistics were also applied as another indication of suitability. The model has a high coefficient of correlation (R = 0.99), MBE = -14 x 10-4 kW h/m2, RMSE = 0.10 kW h/m2, and MPE = -0.03%. It is believed that the model developed in this work is applicable for estimating, with great accuracy. The monthly mean daily global radiation at any site having similar conditions to those found in Tabouk. Furthermore, 29 regression models available in the literature were used to estimate the global solar radiation data for Tabouk. The selected models were different in terms of the variables they use and in the number of the variables they contained. The models were compared on the basis of the statistical errors considered above. Apart from Abdall's model, which showed a reasonable Abdall's model, which showed a reasonable estimate (MPE = -2.04%, MBE = -0.22 kW h/m2, and RMSE = 0.59 kW h/m2), all the models under or overestimate the measured solar radiation values. Comparisons between these models and the produced model, from this study, were also considered. According to the statistical results, the model of Abdall showed the prediction closest to those estimated using the developed model.

228

Modeling of combustion in stratified hydrogen-air mixtures  

OpenAIRE

This work provides a detailed and fundamental study of the propagation behavior of flames from an ignition source in hydrogen-air stratified layers, and explores approaches to their modeling. The understanding gained can be useful for practical applications like direct-injection spark-ignited (DISI) hydrogen engines. Beyond hydrogen applications, this research is also relevant to flame propagation in stratified fuel-air mixtures in general. ^ Initial comparisons with published results show ...

Owston, Rebecca A.

2010-01-01

229

Modelling the emission of pesticides from covered structures to air  

OpenAIRE

Emissions of plant protection products (PPP) from covered structures to the air outside were estimated to support the European Food Safety Authority (EFSA) in the development of guidance on risk assessments for protected crops. Such emissions are mainly caused by loss of volatilised PPPs through the vents in the covered structures. The newly developed VEGA model (Ventilated Emissions from Greenhouse to Air) describes the fate of PPPs after a spray application inside covered structures. Simula...

Holterman, H. J.; Sapounas, A.; Beulke, S.; Os, E. A.; Glass, C. R.

2012-01-01

230

Modeling the ascent of sounding balloons: derivation of the vertical air motion  

Science.gov (United States)

A new model to describe the ascent of sounding balloons in the troposphere and lower stratosphere (up to ?30-35 km altitude) is presented. Contrary to previous models, detailed account is taken of both the variation of the drag coefficient with altitude and the heat imbalance between the balloon and the atmosphere. To compensate for the lack of data on the drag coefficient of sounding balloons, a reference curve for the relationship between drag coefficient and Reynolds number is derived from a dataset of flights launched during the Lindenberg Upper Air Methods Intercomparisons (LUAMI) campaign. The transfer of heat from the surrounding air into the balloon is accounted for by solving the radial heat diffusion equation inside the balloon. In its present state, the model does not account for solar radiation, i.e. it is only able to describe the ascent of balloons during the night. It could however be adapted to also represent daytime soundings, with solar radiation modeled as a diffusive process. The potential applications of the model include the forecast of the trajectory of sounding balloons, which can be used to increase the accuracy of the match technique, and the derivation of the air vertical velocity. The latter is obtained by subtracting the ascent rate of the balloon in still air calculated by the model from the actual ascent rate. This technique is shown to provide an approximation for the vertical air motion with an uncertainty error of 0.5 m s-1 in the troposphere and 0.2 m s-1 in the stratosphere. An example of extraction of the air vertical velocity is provided in this paper. We show that the air vertical velocities derived from the balloon soundings in this paper are in general agreement with small-scale atmospheric velocity fluctuations related to gravity waves, mechanical turbulence, or other small-scale air motions measured during the SUCCESS campaign (Subsonic Aircraft: Contrail and Cloud Effects Special Study) in the orographically unperturbed mid-latitude middle troposphere.

Gallice, A.; Wienhold, F. G.; Hoyle, C. R.; Immler, F.; Peter, T.

2011-10-01

231

A modeling perspective on cloud radiative forcing  

International Nuclear Information System (INIS)

Radiation fields from a perpetual July integration of a T106 version of the ECM-WF operational model are used to identify the most appropriate way to diagnose cloud radiative forcing in a general circulation model, for the purposes of intercomparison between models. Differences between the Methods I and II of Cess and Potter (1987) and a variant method are addressed. Method I is shown to be the least robust of all methods, due to the potential uncertainties related to persistent cloudiness, length of the sampling period and biases in retrieved clear-sky quantities due to insufficient sampling of the diurnal cycle. Method II is proposed as an unambiguous way to produce consistent radiative diagnostics for intercomparing model results. The impact of the three methods on the derived sensitivities and cloud feedbacks following an imposed change in sea surface temperature is discussed. The sensitivity of the results to horizontal resolution is considered by using the diagnostics from parallel integrations with T21 version of the model

232

Measurement and simulation of the in-flight radiation exposure on different air routes  

International Nuclear Information System (INIS)

The exposure of air-crew personnel to cosmic radiation is considered to be occupational exposure and requirements for dose assessment are given in the European Council Directive 96/29/EURATOM. The High-Temperature Ratio (HTR) Method for LiF: Mg, Ti TLDs utilizes the well-investigated relative intensity of the combined high-temperature glow peaks 6 and 7 compared with the dominant peak 5 (left-hand side of Figure 1) as an indication of the dose-average LET of a mixed radiation field of unknown composition. The difference in the peak-5 readings of the neutron-sensitive TLD-600 (6LiF: Mg, Ti) and the neutron-insensitive TLD-700 (7LiF: Mg, Ti) can be utilized to assess the neutron dose equivalent accumulated in-flight. For this purpose, the dosemeter crystals were calibrated individually in the CERN-EU High Energy Reference Field (CERF) [8] which simulates the cosmic-ray induced neutron spectrum in good detail. The experiments conducted onboard passenger aircraft on different north-bound and trans-equatorial flight routes were aimed at the following: to measure the total dose equivalent accumulated during the flight, to assess the contribution of neutrons, and to compare the results with calculations by means of the well-known CARI computer code. Measurements were performed on a series of eight north-bound flights between Cologne and Washington as well as on the routes Vienna-Atlanta, Vienna-Sydney and Vienna-Tokyo during different solar activity conditions. Precise altitude and route profiles were recorded by the pilots. The experimental results were compared with model calculations using the latest release 6M of the CARI code. Precise altitude and route data on a ten-minute to one-hour scale were taken as input. The calculated dose values indicate that the algorithms employed for the computational assessment of route doses have been significantly improved during the last decade. The CARI results generally tend to be in reasonable agreement with the measured values, although the doses for north-bound flights during solar minimum might still be underestimated by up to 15 %. The most important insufficiency in all computational approaches regards the effects of major solar particle events (SPEs) presenting a serious danger primarily for future high-altitude and polar-orbital flights in causing severe biological hazards. The frequency of these irregular events corresponds to the solar activity cycle. This fact is taken into account in the codes by semi-empirical models which certainly have to fail in forecasting accurate dose values for a specific flight. Therefore, dosimetric surveillance of air-crew members would be essential and cannot be completely replaced by calculations. (authors)

233

Sigmoidal response model for radiation risk  

International Nuclear Information System (INIS)

From epidemiologic studies, we find no measurable increase in the incidences of birth defects and cancer after low-level exposure to radiation. Based on modern understanding of the molecular basis of teratogenesis and cancer, I attempt to explain thresholds observed in atomic bomb survivors, radium painters, uranium workers and patients injected with Thorotrast. Teratogenic injury induced by doses below threshold will be completely eliminated as a result of altruistic death (apoptosis) of injured cells. Various lines of evidence obtained show that oncomutations produced in cancerous cells after exposure to radiation are of spontaneous origin and that ionizing radiation acts not as an oncomutation inducer but as a tumor promoter by induction of chronic wound-healing activity. The tissue damage induced by radiation has to be repaired by cell growth and this creates opportunity for clonal expansion of a spontaneously occurring preneoplastic cell. If the wound-healing error model is correct, there must be a threshold dose range of radiation giving no increase in cancer risk. (author)

234

Sigmoidal response model for radiation risk  

Energy Technology Data Exchange (ETDEWEB)

From epidemiologic studies, we find no measurable increase in the incidences of birth defects and cancer after low-level exposure to radiation. Based on modern understanding of the molecular basis of teratogenesis and cancer, I attempt to explain thresholds observed in atomic bomb survivors, radium painters, uranium workers and patients injected with Thorotrast. Teratogenic injury induced by doses below threshold will be completely eliminated as a result of altruistic death (apoptosis) of injured cells. Various lines of evidence obtained show that oncomutations produced in cancerous cells after exposure to radiation are of spontaneous origin and that ionizing radiation acts not as an oncomutation inducer but as a tumor promoter by induction of chronic wound-healing activity. The tissue damage induced by radiation has to be repaired by cell growth and this creates opportunity for clonal expansion of a spontaneously occurring preneoplastic cell. If the wound-healing error model is correct, there must be a threshold dose range of radiation giving no increase in cancer risk. (author)

Kondo, Sohei [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

1995-12-01

235

Overshooting dynamics in a model adaptive radiation.  

Science.gov (United States)

The history of life is punctuated by repeated periods of unusually rapid evolutionary diversification called adaptive radiation. The dynamics of diversity during a radiation reflect an overshooting pattern with an initial phase of exponential-like increase followed by a slower decline. Much attention has been paid to the factors that drive the increase phase, but far less is known about the causes of the decline phase. Decreases in diversity are rarely associated with climatic changes or catastrophic events, suggesting that they may be an intrinsic consequence of diversification. We experimentally identify the factors responsible for losses in diversity during the later stages of the model adaptive radiation of the bacterium Pseudomonas fluorescens. Proximately, diversity declines because of the loss of biofilm-forming niche specialist morphotypes. We show that this loss occurs despite the presence of strong divergent selection late in the radiation and is associated with continued adaptation of resident niche specialists to both the biotic and abiotic environments. These results suggest that losses of diversity in the latter stages of an adaptive radiation may be a general consequence of diversification through competition and lends support to the idea that the conditions favouring the emergence of diversity are different from those that ensure its long-term maintenance. PMID:20554549

Meyer, Justin R; Schoustra, Sijmen E; Lachapelle, Josianne; Kassen, Rees

2011-02-01

236

A PHOTOCHEMICAL BOX MODEL FOR URBAN AIR QUALITY SIMULATION  

Science.gov (United States)

A simple 'box-approach' to air quality simulation modeling has been developed in conjunction with a newly formulated photochemical kinetic mechanism to produce an easily applied Photochemical Box Model (PBM). This approach represents an urban area as a single cell 20 km in both l...

237

MODTRAN4 version 2: radiative transfer modeling  

Science.gov (United States)

MODTRAN4, version 2, will soon be released by the U.S. Air Force Geophysics Laboratory; it is an extension of the MODTRAN4, v1, atmospheric transmission, radiance and flux model developed jointly by the Air Force Research Laboratory / Space Vehicles Directorate (AFRL / VS) and Spectral Sciences, Inc. The primary accuracy improvements in MODTRAN4 remain those previously published: (1) the multiple scattering correlated-k approach to describe the statistically expected transmittance properties for each spectral bin and atmospheric layer, and (2) the Beer-Lambert formulation that improves the treatment of path inhomogeneities. Version 2 code enhancements are expected to include: *pressure-dependent atmospheric profile input, as an auxiliary where the hydrostatic equation is integrated explicitly to compute the altitudes, *CFC cross-sections with band model parameters derived from pseudo lines, *additional pressure-induced absorption features from O2, and *a new 5 cm-1 band model option. Prior code enhancements include the incorporation of solar azimuth dependence in the DISORT-based multiple scattering model, the introduction of surface BRDF (Bi-directional Radiance Distribution Functions) models and a 15 cm-1 band model for improved computational speed. Last year's changes to the HITRAN database, relevant to the 0.94 and 1.13 micrometers bands of water vapor, have been maintained in the MODTRAN4,v2 databases.

Anderson, Gail P.; Berk, Alexander; Acharya, Prabhat K.; Matthew, Michael W.; Bernstein, Lawrence S.; Chetwynd, James H., Jr.; Dothe, H.; Adler-Golden, Steven M.; Ratkowski, Anthony J.; Felde, Gerald W.; Gardner, James A.; Hoke, Michael L.; Richtsmeier, Steven C.; Jeong, Laila S.

2001-08-01

238

Sensitivities of radiative-convective climate models  

International Nuclear Information System (INIS)

We have compared sensitivities of four different radiative-convective climate models. Although surface temperature sensitivities with respect to changes in solar constant and atmospheric, CO2 concentration are almost the same in all models, sensitivity with respect to some other climate variables varies up to a factor of 2. We have found that the surface temperature sensitivity with respect to changes of the lapse rate is high in all models, and we emphasize the importance of a lapse rate--surface temperature feedback

239

Diffusion model for lightning radiative transfer  

Science.gov (United States)

A one-speed Boltzmann transport theory, with diffusion approximations, is applied to study the radiative transfer properties of lightning in optically thick thunderclouds. Near-infrared (lambda = 0.7774 micrometers) photons associated with a prominent oxygen emission triplet in the lightning spectrum are considered. Transient and spatially complex lightning radiation sources are placed inside a rectangular parallelepiped thundercloud geometry and the effects of multiple scattering are studied. The cloud is assumed to be composed of a homogeneous collection of identical spherical water droplets, each droplet a nearly conservative, anisotropic scatterer. Conceptually, we treat the thundercloud like a nuclear reactor, with photons replaced by neutrons, and utilize standard one-speed neutron diffusion techniques common in nuclear reactor analyses. Valid analytic results for the intensity distribution (expanded in spherical harmonics) are obtained for regions sufficiently far from sources. Model estimates of the arrival-time delay and pulse width broadening of lightning signals radiated from within the cloud are determined and the results are in good agreement with both experimental data and previous Monte Carlo estimates. Additional model studies of this kind will be used to study the general information content of cloud top lightning radiation signatures.

Koshak, William J.; Solakiewicz, Richard J.; Phanord, Dieudonne D.; Blakeslee, Richard J.

1994-01-01

240

A space radiation test model study  

Science.gov (United States)

The tools for dynamic modeling of the energetic populations in the outer radiation belts are being developed to better understand the extreme variations of particle flux in response to magnetospheric and solar activity. The study utilizes the SCATHA SC3 high-energy electron data for energies from 200 keV to 2 MeV, with fine pitch-angle measurements over the L-shell range of 5.3 to 7 for quiet and moderate geomagnetic periods in April 1979 and June 1980. A solution of the simultaneous bimodal (radial and pitch-angle) diffusion equation for the radiation belts was developed with special regard for the requirements of satellite radiation belt data analysis. The solution was used to test the bimodal theory of outer-electron-belt diffusion by confronting it with satellite data. The data representation requires and provides diffusion parameters that are in agreement with all previous experimental and theoretical determinations of such diffusion coefficients. Such a representation satisfies the basic requirements towards the dynamic modeling of the outer electron radiation belt for L is less than 7 at quiet and moderate geomagnetic conditions. The presentation was also shown to be unique when projected off of the satellite trajectory in (L,t)-space. For L about 7 the representation has difficulties with butterfly distributions that may signify energetic electron encounters with the magnetopause.

Nightingale, R. W.; Chiu, Y. T.; Davidson, G. T.; Francis, W. E.; Rinaldi, M. A.

1989-02-01

241

Biologically based multistage modeling of radiation effects  

Energy Technology Data Exchange (ETDEWEB)

This past year we have made substantial progress in modeling the contribution of homeostatic regulation to low-dose radiation effects and carcinogenesis. We have worked to refine and apply our multistage carcinogenesis models to explicitly incorporate cell cycle states, simple and complex damage, checkpoint delay, slow and fast repair, differentiation, and apoptosis to study the effects of low-dose ionizing radiation in mouse intestinal crypts, as well as in other tissues. We have one paper accepted for publication in ''Advances in Space Research'', and another manuscript in preparation describing this work. I also wrote a chapter describing our combined cell-cycle and multistage carcinogenesis model that will be published in a book on stochastic carcinogenesis models edited by Wei-Yuan Tan. In addition, we organized and held a workshop on ''Biologically Based Modeling of Human Health Effects of Low dose Ionizing Radiation'', July 28-29, 2005 at Fred Hutchinson Cancer Research Center in Seattle, Washington. We had over 20 participants, including Mary Helen Barcellos-Hoff as keynote speaker, talks by most of the low-dose modelers in the DOE low-dose program, experimentalists including Les Redpath (and Mary Helen), Noelle Metting from DOE, and Tony Brooks. It appears that homeostatic regulation may be central to understanding low-dose radiation phenomena. The primary effects of ionizing radiation (IR) are cell killing, delayed cell cycling, and induction of mutations. However, homeostatic regulation causes cells that are killed or damaged by IR to eventually be replaced. Cells with an initiating mutation may have a replacement advantage, leading to clonal expansion of these initiated cells. Thus we have focused particularly on modeling effects that disturb homeostatic regulation as early steps in the carcinogenic process. There are two primary considerations that support our focus on homeostatic regulation. First, a number of epidemiologic studies using multistage carcinogenesis models that incorporate the ''initiation, promotion, and malignant conversion'' paradigm of carcinogenesis are indicating that promotion of initiated cells is the most important cellular mechanism driving the shape of the age specific hazard for many types of cancer. Second, we have realized that many of the genes that are modified in early stages of the carcinogenic process contribute to one or more of four general cellular pathways that confer a promotional advantage to cells when these pathways are disrupted.

William Hazelton; Suresh Moolgavkar; E. Georg Luebeck

2005-08-30

242

A Hybrid Neural Network Prediction Model of Air Ticket Sales  

Directory of Open Access Journals (Sweden)

Full Text Available Air ticket sales revenue is an important source of revenue for travel agencies, and if future air ticket sales revenue can be accurately forecast, travel agencies will be able to advance procurement to achieve a sufficient amount of cost-effective tickets. Therefore, this study applied the Artificial Neural Network (ANN and Genetic Algorithms (GA to establish a prediction model of travel agency air ticket sales revenue. By verifying the empirical data, this study proved that the established prediction model has accurate prediction power, and MAPE (mean absolute percentage error is only 9.11%. The established model can provide business operators with reliable and efficient prediction data as a reference for operational decisions.

Han-Chen Huang

2013-11-01

243

An updated model for millimeter wave propagation in moist air  

Science.gov (United States)

A practical atmospheric Millimeter-Wave Propagation Model is formulated that predicts attenuation, delay, and noise properties of moist air for frequencies up to 1000 GHz. Input variables are height distributions (0-30 km) of pressure, temperature, humidity, and suspended droplet concentration along an anticipated radio path. Spectroscopic data consists of more than 450 parameters describing local O2 and H2O absorption lines complemented by continuum spectra for dry air, water vapor, and hydrosols. For a model limited to frequencies below GHz, the number of spectroscopic parameters can be reduced to less than 200. Recent laboratory measurements at 138 GHz absolute attenuation rates for simulated air with water vapor pressures up to saturation allow the formulation of an improved, though empirical water vapor continuum. Model predictions are compared with selected (2.5-430 GHz) data from both laboratory and field experiments. In general, good agreement is obtained.

Liebe, H. J.

1985-10-01

244

Development of a distributed air pollutant dry deposition modeling framework  

International Nuclear Information System (INIS)

A distributed air pollutant dry deposition modeling system was developed with a geographic information system (GIS) to enhance the functionality of i-Tree Eco (i-Tree, 2011). With the developed system, temperature, leaf area index (LAI) and air pollutant concentration in a spatially distributed form can be estimated, and based on these and other input variables, dry deposition of carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter less than 10 microns (PM10) to trees can be spatially quantified. Employing nationally available road network, traffic volume, air pollutant emission/measurement and meteorological data, the developed system provides a framework for the U.S. city managers to identify spatial patterns of urban forest and locate potential areas for future urban forest planting and protection to improve air quality. To exhibit the usability of the framework, a case study was performed for July and August of 2005 in Baltimore, MD. - Highlights: ? A distributed air pollutant dry deposition modeling system was developed. ? The developed system enhances the functionality of i-Tree Eco. ? The developed system employs nationally available input datasets. ? The developed system is transferable to any U.S. city. ? Future planting and protection spots were visually identified in a case study. - Employing nationally available datasets and a GIS, this study will provide urban forest managers in U.S. ciurban forest managers in U.S. cities a framework to quantify and visualize urban forest structure and its air pollution removal effect.

245

An inexact fuzzy-chance-constrained air quality management model.  

Science.gov (United States)

Regional air pollution is a major concern for almost every country because it not only directly relates to economic development, but also poses significant threats to environment and public health. In this study, an inexact fuzzy-chance-constrained air quality management model (IFAMM) was developed for regional air quality management under uncertainty. IFAMM was formulated through integrating interval linear programming (ILP) within a fuzzy-chance-constrained programming (FCCP) framework and could deal with uncertainties expressed as not only possibilistic distributions but also discrete intervals in air quality management systems. Moreover, the constraints with fuzzy variables could be satisfied at different confidence levels such that various solutions with different risk and cost considerations could be obtained. The developed model was applied to a hypothetical case of regional air quality management. Six abatement technologies and sulfur dioxide (SO2) emission trading under uncertainty were taken into consideration. The results demonstrated that IFAMM could help decision-makers generate cost-effective air quality management patterns, gain in-depth insights into effects of the uncertainties, and analyze tradeoffs between system economy and reliability. The results also implied that the trading scheme could achieve lower total abatement cost than a nontrading one. PMID:20681428

Xu, Ye; Huang, Guohe; Qin, Xiaosheng

2010-07-01

246

Air-quality investigation in the NIH (National Institutes of Health) Radiation Oncology Branch  

International Nuclear Information System (INIS)

The Radiation Oncology Branch (ROB) is located in the Clinical Center of the National Institutes of Health (NIH). The occupants of the ROB facility have expressed dissatisfaction with the air-quality within the facility for several years. To identify the sources of the air quality problems in the ROB facility and to obtain recommendations for their solution, the Center for Building Technology at the National Institute of Standards and Technology (NIST, formerly The National Bureau of Standards) conducted an indoor-quality investigation of the ROB facility. Results revealed several deficiencies in the design and current condition of the ROB ventilation system, such as significant differences between the design airflow rates and those recommended in current standards and guidelines. The airflow measurements showed many instances in which measured airflow rates were different from their design values and revealed the existence of airflows leading to the potential for pollutant transport within the building. The contaminant measurements fell generally well below the maximum values in the ASHRAE air-quality standard. Thermal-comfort measurements revealed instances when the temperature and relative humidity were outside of ASHRAE comfort limits. Recommendations are made to remedy the deficiencies noted and to control the conditions contributing to the building's air-quality problems

247

Artificial neural network estimation of global solar radiation using air temperature and relative humidity  

International Nuclear Information System (INIS)

Measured air temperature and relative humidity values between 1998 and 2002 for Abha city in Saudi Arabia were used for the estimation of global solar radiation (GSR) in future time domain using artificial neural network method. The estimations of GSR were made using three combinations of data sets namely: (i) day of the year and daily maximum air temperature as inputs and GSR as output, (ii) day of the year and daily mean air temperature as inputs and GSR as output and (iii) time day of the year, daily mean air temperature and relative humidity as inputs and GSR as output. The measured data between 1998 and 2001 were used for training the neural networks while the remaining 240 days' data from 2002 as testing data. The testing data were not used in training the neural networks. Obtained results show that neural networks are well capable of estimating GSR from temperature and relative humidity. This can be used for estimating GSR for locations where only temperature and humidity data are available

248

Pulsar Radiation Models - Radio to High Energies  

Science.gov (United States)

Rotation-powered pulsars emit over nearly 19 decades of energy. Although an all-encompassing answer as to the origin of this broad-band emission remains elusive nearly 50 years after their discovery, the theorist does have a few tools in his / her toolkit to aid investigation. Phase-averaged spectra give clues as to the emitting particles, their acceleration, environment, and the radiation mechanism. Moreover, the phase-evolution of spectra constrains the radiation energetics and environment as different parts of the magnetosphere are exposed to the observer during the pulsar's rotation. A detailed model furthermore critically depends on the specification of the emission geometry. Modeling the light curves probes this fundamental geometric assumption, which is closely tied to the posited magnetospheric structure. Studying many versions of the same system helps to constrain critical population-averaged quantities, discover population trends, and probe model performance for different regions of phase space. When coupled with population synthesis, such modeling can provide powerful discrimination between competing emission models. Polarization properties may provide complementary constraints on the magnetic field orientation and pulsar geometry. Lastly, comparison of parameters inferred from independent models for the different wavebands yields necessary crosschecks. It is indeed fortunate that the past few years have witnessed an incredible increase in number and improved characterization of rotation-powered pulsars. We will review how the enhanced quality and quantity of data are providing impetus for further model refinement.

Venter, Christo; Harding, Alice

249

Mathematical modeling of compression processes in air-driven boosters  

International Nuclear Information System (INIS)

The compressed air in normal pressure is used as the source of power of the air-driven booster. The continuous working of air-driven boosters relies on the difference of surface area between driven piston and driving piston, i.e., the different forces acting on the pistons. When the working surface area of the driving piston for providing power is greater than that of the driven piston for compressing gas, the gas in compression chamber will be compressed. On the basis of the first law of thermodynamics, the motion regulation of piston is analyzed and the mathematical model of compression processes is set up. Giving a calculating example, the vary trends of gas pressure and pistons' move in working process of booster have been gotten. The change of parameters at different working conditions is also calculated and compared. And the corresponding results can be referred in the design of air-driven boosters

250

Radiation damage of paper samples in in-air PIXE analysis  

International Nuclear Information System (INIS)

Degradation of paper caused by beam irradiation was investigated from a viewpoint of discoloration in PIXE analysis and its application to the paper samples of archaeology. Two types of paper (Japanese paper and fine quality paper) were tested in in-air PIXE analysis with 3 MeV protons. The degree of discoloration was quantitatively measured by the use of a colorimeter. The degree of discoloration was different for each tested paper and corresponded to the radiation dose of ions. It is resulted that even the in-air PIXE analysis should be carefully applied to archaeological treasures. Because discoloration of all tested paper decreased gradually at first but then increased after a few weeks. However, this phenomenon can be used to develop a technique of funny coloration. (author)

251

Direct radiative effect of the Russian wildfires and its impact on air temperature and atmospheric dynamics during August 2010  

Science.gov (United States)

In this study, we investigate the shortwave aerosol direct radiative forcing (ADRF) and its feedback on air temperature and atmospheric dynamics during a major fire event that occurred in Russia during August 2010. The methodology is based on an offline coupling between the CHIMERE chemistry-transport and the Weather Research and Forecasting (WRF) models. First, simulations for the period 5-12 August 2010 have been evaluated by using AERONET (AErosol RObotic NETwork) and satellite measurements of the POLarization and Directionality of the Earth's Reflectance (POLDER) and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) sensors. During this period, elevated POLDER aerosol optical thickness (AOT) is found over a large part of eastern Europe, with values above 2 (at 550 nm) in the aerosol plume. According to CALIOP observations, particles remain confined to the first five kilometres of the atmospheric layer. Comparisons with satellite measurements show the ability of CHIMERE to reproduce the regional and vertical distribution of aerosols during their transport from the source region. Over Moscow, AERONET measurements indicate an important increase of AOT (340 nm) from 0.7 on 5 August to 2-4 between 6 and 10 August when the aerosol plume was advected over the city. Particles are mainly observed in the fine size mode (radius in the range 0.2-0.4 ?m) and are characterized by elevated single-scattering albedo (SSA) (0.95-0.96 between 440 and 1020 nm). Comparisons of simulations with AERONET measurements show that aerosol physical-optical properties (size distribution, AOT, SSA) have been well simulated over Moscow in terms of intensity and/or spectral dependence. Secondly, modelled aerosol optical properties have been used as input in the radiative transfer code of WRF to evaluate their direct radiative impact. Simulations indicate a significant reduction of solar radiation at the ground (up to 80-150 W m-2 in diurnal averages over a large part of eastern Europe due to the presence of the aerosol plume. This ADRF causes an important reduction of the near-surface air temperature between 0.2 and 2.6° on a regional scale. Moscow has been affected by the aerosol plume, especially between 6 and 10 August. During this period, aerosol causes a significant reduction of surface shortwave radiation (up to 70-84 W m-2 in diurnal averages) with a moderate part (20-30%) due to solar absorption within the aerosol layer. The resulting feedbacks lead to a cooling of the air up to 1.6° at the surface and 0.1° at an altitude of 1500-2000 m (in diurnal averages), that contribute to stabilize the atmospheric boundary layer (ABL). Indeed, a reduction of the ABL height of 13 to 65% has been simulated during daytime in presence of aerosols. This decrease is the result of a lower air entrainment as the vertical wind speed in the ABL is shown to be reduced by 5 to 80% (at midday) when the feedback of the ADRF is taken into account. However, the ADRF is shown to have a lower impact on the horizontal wind speed, suggesting that the dilution of particles would be mainly affected by the weakening of the ABL development and associated vertical entrainment. Indeed, CHIMERE simulations driven by the WRF meteorological fields including this ADRF feedback result in a large increase in the modelled near-surface PM10 concentrations (up to 99%). This is due to their lower vertical dilution in the ABL, which tend to reduce model biases with the ground PM10 values observed over Moscow during this specific period.

Péré, J. C.; Bessagnet, B.; Mallet, M.; Waquet, F.; Chiapello, I.; Minvielle, F.; Pont, V.; Menut, L.

2014-02-01

252

Direct radiative effect of the Russian wildfires and their impact on air temperature and atmospheric dynamics during August 2010  

Science.gov (United States)

The present study aims at investigating the shortwave aerosol direct radiative forcing (ADRF) and its feedback on air temperature and atmospheric dynamics during a major fire event that occurred in Russia during August 2010. The methodology is based on an off-line coupling between the CHIMERE chemistry-transport and the Weather Research and Forecasting (WRF) models. First, simulations for the period 5-12 August 2010 have been evaluated by using AERONET and satellite measurements of the POLarization and Directionality of the Earth's Reflectance (POLDER) and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) sensors. During this period, elevated POLDER AOT are found over a large part of Eastern Europe with values above 2 (at 550 nm) in the aerosol plume. According to CALIOP observations, particles remain confined within the first five kilometres of the atmospheric layer. Comparisons with satellite measurements show the ability of CHIMERE to reproduce the regional and vertical distribution of aerosols during their transport from the source region. Over Moscow, AERONET measurements indicate an important increase of AOT (340 nm) from 0.7 on 5 August to 2-4 between 6 and 10 August when the aerosol plume is advected over the city. Particles are mainly observed in the fine size mode (radius in the range 0.2-0.4 ?m) and are characterized by elevated SSA (0.95-0.96 between 440 and 1020 nm). Also, comparisons of simulations with AERONET measurements show that aerosol physical-optical properties (size distribution, AOT, SSA) have been well simulated over Moscow in term of intensity and/or spectral dependence. Secondly, modelled aerosol optical properties have been used as input in the radiative transfer code of WRF to evaluate their direct radiative impact. Simulations indicate a significant reduction of solar radiation at the ground (up to 80-150 W m-2 in diurnal-averaged) over a large part of Eastern Europe due to the presence of the aerosol plume. This ADRF causes an important reduction of the near-surface air temperature between 0.2 and 2.6°C at a regional scale. Moscow has been also affected by the aerosol plume, especially between 6 and 10 August. During this period, aerosol causes a significant reduction of surface shortwave radiation (up to 70-84 W m-2 in diurnal-averaged) with a moderate part (20-30%) due to solar absorption within the aerosol layer. The resulting feedbacks lead to a cooling of the air up to 1.6°C at the surface and 0.1°C at an altitude of 1500-2000 m (in diurnal-averaged), that contribute to stabilize the atmospheric boundary layer (ABL). Indeed, a reduction of the ABL height of 13 to 65% have been simulated during daytime in presence of aerosols. This decrease is the result of a lower air entrainment as the vertical wind speed in the ABL is shown to be reduced by 5 to 80% (at midday) when the feedback of the ADRF is taken into account. In turn, CHIMERE simulations driven by the WRF meteorological fields including this ADRF feedback result in a large increase in the modeled near-surface PM10 concentrations (up to 99%) due to their lower vertical dilution in the ABL, which tend to reduce model biases with the ground PM10 values observed over Moscow during this specific period.

Péré, J. C.; Bessagnet, B.; Mallet, M.; Waquet, F.; Chiapello, I.; Minvielle, F.; Pont, V.; Menut, L.

2013-06-01

253

REAS3: A revised implementation of the geosynchrotron model for radio emission from air showers  

CERN Document Server

Over the past years, the freely available Monte Carlo-code REAS which simulates radio emission from air showers based on the geosynchrotron model, was used regularly for comparisons with data. However, it emerged that in the previous version of the code, emission due to the variation of the number of charged particles within an air shower was not taken into account. In the following article, we show the implementation of these emission contributions in REAS3 by the inclusion of ``end-point contributions'' and discuss the changes on the predictions of REAS obtained by this revision. The basis for describing radiation processes is an universal description which is gained by the use of the end-point formulation. Hence, not only pure geomagnetic radiation is simulated with REAS3 but also radiation due to the variation of the net charge excess in the air shower, independent of the Earth's magnetic field. Furthermore, we present a comparison of lateral distributions of LOPES data with REAS3-simulated distributions....

Ludwig, Marianne

2010-01-01

254

Simplified model for a ventilated glass window under forced air flow conditions  

International Nuclear Information System (INIS)

This paper presents a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow. The proposed model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid. The external glass sheet of the cavity is subjected to variable heat flow due to the solar radiation as well as variable external ambient temperature. The exchange of radiation energy (infrared radiation) between the glass sheets is also included in the formulation. Effects of the spacing between the glass sheets, variation of the forced mass flow rate on the total heat gain and the shading coefficients are investigated. The results show that the effect of the increase of the mass flow rate is found to reduce the mean solar heat gain and the shading coefficients while the increase of the fluid entry temperature is found to deteriorate the window thermal performance

255

Evaluation of the quality of hot air dehydrated onion coming from gamma radiated bulbs  

International Nuclear Information System (INIS)

The purpose of this work was to evaluate the quality of hot air dehydrated onion, as regards physical and chemical characteristics, coming from the regional product that was gamma irradiated for sprout inhibition. We worked with the onion variety Valenciana Sintetica 14. Radio inhibition was made 30 days post harvest with gamma radiation from a 60Co source at the Centro Atomico Ezeiza-CNEA, using a dose of 60 Gy. The skin of the bulbs was manually removed and the bulbs were cut in pieces 3 mm thick and between 1 and 3 cm long. The material was dehydrated in a rotating dryer with forced air circulation at 60 C degrees, between 0.8 and 1.7 m/s air speed and at ambient relative humidity. Dehydration was made 80 days after post-irradiation. The quality of the dehydrated onion was evaluated by the following physical- chemical analysis: total solids content, pungency (indirectly measured by pyruvic acid content assessment), color, pH, carbon hydrates and sensorial analysis. All analytical determinations were made in triplicate. The results obtained showed there are no significant changes between the averages of the physical-chemical properties of the control dehydrated samples and those coming from the radio-inhibited raw matter. According to the sensorial analysis, only the color of dehydrated onion was affected by the radio inhibition process. However, and according to the panel members comment, the greatest browning degree observed in ionizing radiation treated onion seemed to result more attractive to them. It may be concluded that radio inhibited regional onion can be useful as raw matter for hot air dehydrated product. It must be remarked that its use would extend the product use by dehydration plants, thus implying an increase of their processing capacity with the corresponding financial benefit. (author)

256

Study on the quasi-steady interaction between CO2 laser radiation and a graphite target in the air  

International Nuclear Information System (INIS)

Spectroscopic, interferometric and photometric diagnostic methods have been employed to study a quasi-steady laser flame initiated by the CO2 laser radiation with the power density of 0.1-2 MW/cm2 on graphite in air. The flame is shown to be a carbon vapor jet transparent for the laser radiation and propagating in the air surrounding the target without its noticeable heating by the laser radiation. Problems are discussed of the flame gas dynamics and thermophysics which are of interest for laser treatment of materials and for development of a laser-heated jet thruster

257

Modeling the Environmental Impact of Air Traffic Operations  

Science.gov (United States)

There is increased interest to understand and mitigate the impacts of air traffic on the climate, since greenhouse gases, nitrogen oxides, and contrails generated by air traffic can have adverse impacts on the climate. The models described in this presentation are useful for quantifying these impacts and for studying alternative environmentally aware operational concepts. These models have been developed by leveraging and building upon existing simulation and optimization techniques developed for the design of efficient traffic flow management strategies. Specific enhancements to the existing simulation and optimization techniques include new models that simulate aircraft fuel flow, emissions and contrails. To ensure that these new models are beneficial to the larger climate research community, the outputs of these new models are compatible with existing global climate modeling tools like the FAA's Aviation Environmental Design Tool.

Chen, Neil

2011-01-01

258

Atmospheric transmittance model for photosynthetically active radiation  

Energy Technology Data Exchange (ETDEWEB)

A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms.

Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana [Physics Department, West University of Timisoara, V Parvan 4, 300223 Timisoara (Romania); Pop, Nicolina [Department of Physical Foundations of Engineering, Politehnica University of Timisoara, V Parvan 2, 300223 Timisoara (Romania); Calinoiu, Delia [Mechanical Engineering Faculty, Politehnica University of Timisoara, Mihai Viteazu 1, 300222 Timisoara (Romania)

2013-11-13

259

Atmospheric transmittance model for photosynthetically active radiation  

International Nuclear Information System (INIS)

A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms

260

Model-generated air quality statistics for application in vegetation response models in Alberta  

International Nuclear Information System (INIS)

To test and apply vegetation response models in Alberta, air pollution statistics representative of various parts of the Province are required. At this time, air quality monitoring data of the requisite accuracy and time resolution are not available for most parts of Alberta. Therefore, there exists a need to develop appropriate air quality statistics. The objectives of the work reported here were to determine the applicability of model generated air quality statistics and to develop by modelling, realistic and representative time series of hourly SO2 concentrations that could be used to generate the statistics demanded by vegetation response models

261

An Analytical Air Pollution Model with Time Dependent Eddy Diffusivity  

Directory of Open Access Journals (Sweden)

Full Text Available Air pollution transport and dispersion in the atmospheric boundary layer are modeled by the advection-diffusion equation, that is, essentially, a statement of conservation of the suspended material in an incompressible flow. Many models simulating air pollution dispersion are based upon the solution (numerical or analytical of the advection-diffusion equation assuming turbulence parameterization for realistic physical scenarios. We present the general time dependent three-dimensional solution of the advection-diffusion equation considering a vertically inhomogeneous atmospheric boundary layer for arbitrary vertical profiles of wind and eddy-diffusion coefficients. Numerical results and comparison with experimental data are shown.

Tiziano Tirabassi

2013-07-01

262

Radiative processes in air excited by an ArF laser  

Science.gov (United States)

The emission spectrum of air that is excited by an ArF laser has been investigated experimentally and theoretically to determine the conditions under which fluorescence from O2 can be used for the measurement of temperature in aerodynamic flows. In addition to the expected fluorescence from O2, the spectrum from excitation with an intense laser beam is shown to contain significant contributions from the near-resonant Raman fundamental and overtone bands, the four-photon fluorescence excitation of C produced from ambient CO2, and possibly the three-photon excitation of O(2+). The nature of the radiative interactions contributing to these additional features is described.

Laufer, Gabriel; Mckenzie, Robert L.; Huo, Winifred M.

1988-01-01

263

Study of filamentation dynamics of ultrashort laser radiation in air: beam diameter effect  

Science.gov (United States)

A single filamentation of femtosecond gigawatt laser radiation with a millimeter-size aperture upon collimated and sharply focused propagation in atmospheric air at 800 nm and 400 nm wavelengths is studied both theoretically and experimentally. The influence of beam initial radius on the parameters of the forming filament is analyzed. Three filament parameters, namely, start coordinate, filament length, and longitudinal continuity are considered. We report that unlike Marburger’s formula the single filamentation onset reveals marked nonquadratic dependence on the laser beam radius providing the same initial pulse power. Additionally, for sharply focused radiation the minor dependence of the filament length on the laser beam diameter at the constant initial pulse intensity was experimentally revealed.

Afonasenko, A. V.; Apeksimov, D. V.; Geints, Y. E.; Golik, S. S.; Kabanov, A. M.; Zemlyanov, A. A.

2014-10-01

264

Numerical modelling of negative discharges in air with experimental validation  

OpenAIRE

Abstract Axisymmetric finite element models have been developed for the simulation of negative discharges in air without and with presence of dielectrics. The models are based on the hydrodynamic drift-diffusion approximation. A set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) are coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. The model...

Tran, T. N.; Golosnoy, I. O.; Lewin, P. L.; Georghiou, G. E.

2011-01-01

265

Modeling Air Stripping of Ammonia in an Agitated Vessel  

Energy Technology Data Exchange (ETDEWEB)

A model has been developed to predict the rate of removal of ammonia (NH{sub 3}) from solution in a sparged agitated vessel. The model is first-order with respect to liquid-phase concentration of NH{sub 3}. The rate constant for the first-order equation is a function of parameters related to the vessel/impeller characteristics, the air/liquid properties as well as the process conditions. However, the vessel/impeller characteristics, the air/liquid properties, and the process conditions reduce the rate constant dependence to only three parameters, namely, the air sparge rate, the liquid volume or batch size, and the Henry's law constant of NH{sub 3} for the liquid or solution. Thus, the rate of removal is not mass-transfer limited. High air sparge rates, high temperatures, and low liquid volumes or batch sizes increase the rate of removal of NH{sub 3} from solution. The Henry's law constant effect is somewhat reflected in the temperature since Henry's law constant increases with increasing temperature. Data obtained from actual air stripping operation agree fairly well with the model predictions.

Kofi, Adu-Wusu; Martino, Christopher J.; Wilmarth, William R.; Bennett, William M.; Peters, Robert s.

2005-11-29

266

Air Pollution Radiative Forcing From Specific Emissions Sectors at 2030: Prototype for a New IPCC Bar Chart  

Science.gov (United States)

Reduction of short-lived air pollutants provides a way to mitigate global warming in the short-term with ancillary benefits to human health. However, the radiative forcings of short-lived air pollutants depend on the location and source type of the precursor emissions. We apply the GISS atmospheric composition-climate model to quantify near future (2030 A1B) ozone (O3) and sulfate global mean direct radiative forcing impacts from 6 emissions sectors from 7 geographic regions. At 2030 the net forcings for the emissions sectors (including O3, sulfate, black and organic carbon forcings) are (in mW/m2): transportation = +106; biomass burning = +69; domestic = +38; power = -158; industry = -124. Hence the transportation sector is the most attractive target to counter global warming via reduction of short-lived air pollutants. Substantial transportation sector O3 forcings come from all regions (5-12 mW/m2). Central and Southern Africa and South America contribute the largest biomass burning O3 forcings (11-15 mW/m2). Domestic biofuel emissions from East Asia, South Asia and Central and South Africa and power and industry emissions from East Asia also contribute substantial O3 forcings (7-15mW/m2). The global mean sulfate forcings are dominated by the power and industry sectors with largest contributions from East Asia, South Asia and North Africa and Middle East (-30 to -50 mW/m2). Linear relationships exist between global mean radiative forcing by O3 and biomass burning and domestic biofuel CO precursor emissions independent of the region of origin with sensitivity of 0.02mW/m2/TgCO. Similarly, linear relationships are available for global mean radiative forcing by sulfate and SO2 precursor emissions that depend upon region but are independent of the emissions sector with sensitivities ranging from -3 to -12mW/m2/TgS. Such emissions to forcing diagnostics will assist development of climate-motivated policy for O3 and sulfate.

Unger, N.; Shindell, D. T.; Koch, D. M.

2007-05-01

267

A model investigation of annual surface ultraviolet radiation in Iran  

International Nuclear Information System (INIS)

In recent years, there has been some concern regarding solar ultraviolet (UV) radiation received at the earth,s surface because of its biological hazards affecting living organisms. Although the geographical distribution of ground-based UV network is relatively good in some continents,but over Asia, the number of UV instruments are not sufficient for meteorological and biological purposes. Iran, as an Asian country, is also suffering from the lack of UV monitoring network with the exception of one ground-based UV spectrophotometer site (Brower III) at Esfahan. Using a complex radiative transfer model and various meteorological data (for 8 years) such as total column ozone, cloudiness, surface albedo, surface air pressure, relative humidity, visibility and daily total solar radiation (TSR), the geographical distribution of annual integrated biological surface UV irradiances such as UVB, erythema and cataracts are calculated. The comparison is made for cloud-free and all-sky conditions for eight selected cities distributed from the southern tip of the country (25 N-60 E) to the northern border (39 N-48 E). It is shown that the difference between the annual UV at south and north in all-sky condition is larger than the differences in cloud-free condition. The ratio of some biological UV irradiances at southern cities to the same component at northern cities shows a factor of two and more which is quite significant. The possible reasons which might cause such differences aasons which might cause such differences are discussed

268

Evaluation of indoor air quality in a department of radiation oncology located underground  

International Nuclear Information System (INIS)

Indoor air quality (IAQ) in the radiation treatment center which is generally located underground is important to the health of hospital workers and patients treated over a long period of time. This study was conducted to measure and analyze the factors related to IAQ and subjective symptoms of sick building syndrome, and to establish the causes influencing IAQ and find a solution to the problems. Self administrated questionnaire was conducted to check the workers' symptoms and understanding of the work environment. Based on a preliminary investigation, the factors related to IAQ such as temperature, humidity, fine particulate, carbon dioxide, carbon monoxide, formaldehyde, total volatile organic compounds (TVOC), and radon gas were selected and measured for a certain period of time in specific sites where hospital workers stay long in a day. And we also evaluated the surrounding environment and the efficiency of the ventilating system simultaneously, and measured the same factors at the first floor (outdoor) to compare with outdoor air quality. All collected data were assessed by the recommended standard for IAQ of the domestic and international environmental organizations. Hospital workers were discontented with foul odors, humidity and particulate. They complained symptoms related to musculo-skeletal system, neurologic system, and mucosal-irritation. Most of the factors were not greater than the recommended standard, but the level of TVOC was third or fourth times e level of TVOC was third or fourth times as much as the measuring level of some offices in the United States. The frequency and the amount of the ventilating system were adequate, however, the problem arising in the position of outdoor-air inlets and indoor-air outlets involved a risk of the indraft of contaminated air. A careful attention was a requirement in handling and keeping chemical substances including a developing solution which has a risk of TVOC emissions, and repositioning the ventilating system was needed to solve the contaminated-air circulation immediately. We verified that some IAQ-related factors and inadequate ventilating system could cause subjective symptoms in hospital workers. The evaluation of IAQ was surely needed to improve the underground working environment for hospital workers and patients. On the basis of these data, from now on, we should actively engage in designs of the department of radiation oncology or improvement in environment of the existing facilities

269

Air-ingress analysis: Part 2-Computational fluid dynamic models  

Energy Technology Data Exchange (ETDEWEB)

Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy (DOE), is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high-temperature reactors (VHTRs). Phenomena identification and ranking studies to date have ranked an air-ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air-ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the high-temperature gas-cooled reactor through the break, possibly causing oxidation of the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of lower plenum graphite because of oxidation might lead to a reactor safety issue. Computational fluid dynamics models developed in this study will improve our understanding of this phenomenon and is used to mitigate air ingress. This paper presents three-dimensional (3D) computational fluid dynamic (CFD) results for the quantitative assessment of the air-ingress phenomena. The 3D CFD simulation results show that the air-ingress accident is not controlled by molecular diffusion but density gradient driven stratified flow when the double-ended-guillotine break is assumed in a horizontal pipe configuration. It concludes that the previous air-ingress scenarios based on the molecular diffusion might not be correct and should be extensively modified to include real phenomena. This paper also presents a preliminary two-dimensional (2D) CFD simulation for validating an air-ingress mitigation concept using helium injection at the lower plenum. This simulation shows that the helium replaces air by buoyancy force and effectively mitigates air-ingress into the core.

Oh, Chang H., E-mail: Chang.Oh@inl.go [Idaho National Laboratory, Idaho Falls, ID 83415-3870 (United States); Kang, Hyung S.; Kim, Eung S. [Idaho National Laboratory, Idaho Falls, ID 83415-3870 (United States)

2011-01-15

270

Stochastic radiation transport for climate models  

International Nuclear Information System (INIS)

Mathematical models are being developed to predict cloud morphology based upon knowledge of the local intrinsic variables such as heating rate and humidity profiles. Among the desired variables are the size distribution, in space and optical depth, of the clouds. The approach is to use ARM data to determine the statistics of observed cloud fields and to calculate the resulting radiation transport in a statistical manner such that average energy balance can be predicted from knowledge of the average statistics. The are four general areas of research in this endeavor: Functional cloud cover; Theory of stochastic transfer; Effect on model calculations; and Tests of stochastic theory

271

Two-dimensional analytical model of dry air thermal convection  

Science.gov (United States)

In the present work, the steady-state stationary dry air thermal convection in a lower atmosphere has been studied theoretically. The thermal convection was considered without accounting for the Coriolis force, and with only the vertical temperature gradient. The stream function has been analytically obtained within the framework of two-dimensional thermal convection model in the Boussinesq approximation with velocity divergence taken as zero. It has been shown that the stream function is symmetrical about the horizontal and vertical. The expressions for the horizontal and vertical air velocity components have been obtained. The maximal vertical velocities level is in the center of the convective cell where the horizontal air velocity component is equal to zero. It has been shown that the air parcel's rotation period during the thermal convection is determined by the Brunt-Väisälä frequency. The expression for the maximal air velocity vertical component has been found. The dependence of the maximal air velocity vertical component on the overheat function at ground surface and on the atmosphere instability has been demonstrated. The expression for the pressure disturbance has been obtained. It has been demonstrated that at the points with maximal pressure disturbance the vertical velocity is equal to zero and the horizontal velocity is maximal. It has been found that the convection cell size depends on the atmosphere stability state.

Zakinyan, R. G.; Zakinyan, A. R.; Lukinov, A. A.

2015-01-01

272

Mathematical modelling of combustion and nitrous oxide emissions of flat flame with high-preheated air  

International Nuclear Information System (INIS)

The combustion and nitrous oxide (N2O) emissions of a flat flame made using high pre-heated air were modelled. A high temperature air combustion (HiTAC) furnace equipped with a single flat flame burner and a regenerative system for preheating air was used in the experimental study. The eddy-dissipation-concept was used to calculate combustion reaction rates. The model was combined with a thermal-N2O model in order to predict N2O formation and emissions. Thermal radiation was modelled using a combined heat flux method with the Monte Carlo method. Results of the modelling study were then compared with results obtained during an experimental study, and combustion characteristics of the flat flame were compared with results obtained for a normal flame in order to investigate the effects of flue gas recirculation on nitrous oxide emissions. Results of the study showed that flue gas recirculation reduced the local temperature of the flame and inhibited nitrous oxide formation. A comparison of the computational model with experimental results demonstrated the accuracy of the algorithm developed in the study. 15 refs., 2 tabs., 7 figs.

273

A Radiative Transfer Model for Climate Calculations  

Science.gov (United States)

This paper describes a radiative transfer model developed to accurately predict the atmospheric radiant flux in both the infrared and the solar spectrum with a minimum of computational effort. We use a newly developed k-distribution model for both the thermal and solar parts of the spectrum. We employ a generalized two-stream approximation for the scattering by aerosol and clouds. To assess the accuracy of the model, the results are compared to other more detailed models for several standard cases in the solar and thermal spectrum. We perform several calculations focussing primarily on the question of absorption of solar radiation by gases and aerosols. We estimate the accuracy of the k-distribution to be approx. 1 W/sq m for the gaseous absorption in the solar spectrum. We estimate the accuracy of the two-stream method to be 3-12 W/sq m for the downward solar flux and 1-5 W/sq m for the upward solar flux at the top of atmosphere depending on the optical depth of the aerosol layer. We also show that the effect of ignoring aerosol absorption on the downward solar flux at the surface is 50 W/sq m for the TARFOX aerosol for an optical depth of 0.5 and 150 W/sq m for a highly absorbing mineral aerosol. Thus, we conclude that the uncertainty introduced by the aerosol solar radiative properties (and merely assuming some "representative" model) can be considerably larger than the error introduced by the use of a two-stream method.

Bergstrom, Robert W.; Mlawer, Eli J.; Sokolik, Irina N.; Clough, Shepard A.; Toon, Owen B.

2000-01-01

274

MODEL PENGELOLAAN AIR BERSIH DESA DI BANTUL YOGYAKARTA  

Directory of Open Access Journals (Sweden)

Full Text Available AbstrakArtikel ini bertujuan mendeskripsikan model pengelolaan air minum desa dan permasalah yang dihadapinya. Penelitian dilakukan di wilayah Pucung Desa Wukirsari Bantul Yogyakarta. Permasalahan yang dikaji adalah bagaimana pengelolaan  ditinjau dari aspek kelembagaan, ketersediaan air, jumlah pengguna, kebutuhan air bersih, pedoman yang mengatur dan manajemen keuangannya. Jenis penelitian survai dengan pendekatan deskriptif kualitatif dan kuantitatif. Subyek penelitian kepala keluarga. Hasil penelitian Pengelolaan Air Bersih (PAB Pucung dikelola berbasis masyarakat (tipe C, namun belum melibatkan pelanggan dalam pengelolaannya. Ketersediaan air sangat cukup, tetapi kebutuhan pelanggan belum terpenuhi secara maksimal. Apabila PAB Pucung dapat beroperasi secara efektif dan efisien masyarakat Pucung tidak akan kekurangan air bersih karena dalam satu bulan masih tersedia 13.445 m3, yang setara  dengan pemenuhan kebutuhan air bersih rata–rata 259 jiwa/bulan.AbstractThis article aims to describe a village water management model and the problems it faces. The study was conducted in the area of ??Bantul, Yogyakarta, to be exactly in Wukirsari village. The article studies water management in the aspect of institutional management, water availability, number of users, the need for clean water, and guidelines governing financial management. The results of the study reveals that the water is managed by the community (type C, and do not involve the customer in its management. Though water is abundant, the management does not meet customer needs to the fullest. If PAB Pucung can operate effectively and efficiently Pucung people will not lack of clean water because of lack of clean water is still available in a month 13 445 m3, which is equivalent to a clean water supply on average 259 people/month.© 2013 Universitas Negeri Semarang

Hardjono -

2014-02-01

275

Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants  

Science.gov (United States)

Control of air contaminants is a crucial factor in the safety considerations of crewed space flight. Indoor air quality needs to be closely monitored during long range missions such as a Mars mission, and also on large complex space structures such as the International Space Station. This work mainly pertains to the detection and simulation of air contaminants in the space station, though much of the work is easily extended to buildings, and issues of ventilation systems. Here we propose a method with which to track the presence of contaminants using an accurate physical model, and also develop a robust procedure that would raise alarms when certain tolerance levels are exceeded. A part of this research concerns the modeling of air flow inside a spacecraft, and the consequent dispersal pattern of contaminants. Our objective is to also monitor the contaminants on-line, so we develop a state estimation procedure that makes use of the measurements from a sensor system and determines an optimal estimate of the contamination in the system as a function of time and space. The real-time optimal estimates in turn are used to detect faults in the system and also offer diagnoses as to their sources. This work is concerned with the monitoring of air contaminants aboard future generation spacecraft and seeks to satisfy NASA's requirements as outlined in their Strategic Plan document (Technology Development Requirements, 1996).

Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

1998-01-01

276

The experimental validation of a CFD model for a heating oven with natural air circulation  

International Nuclear Information System (INIS)

This paper discusses a 3-D Computational Fluid Dynamics (CFD) model and presents experimental analysis of the flow and thermal processes within a laboratory heating oven with a natural air circulation. This device is used to store laboratory samples and products at a high, constant and spatially uniform temperature. The mathematical model included heat conduction in the insulated walls and convective and radiative (between walls) heat transfer in the volume of air within the oven. To formulate the mathematical model, a number of experiments were carried out to determine the temperature boundary conditions along the U-shaped heaters and the emissivity of the internal and external walls to determine the radiative heat fluxes. In addition, to validate the spatial temperature and velocity fields in the storage chamber and on the external oven walls, a set of thermocouples and Particle Image Velocimetry (PIV) were employed. The existing device was assessed in four configurations using a certification procedure that was performed at its maximum temperature level. The device was then numerically simulated using the mathematical model developed for this study. The results show satisfactory agreement between the experimental and computational velocity and temperature values. Furthermore, this study developed potential changes for the construction of this device that will improve the temperature uniformity within the storage space. -- Highlights: ? Temperature uniformity of oven was examined. ? The CFD model of drying oven was satisfactory validated. ? Potential modifications of drying oven were shown

277

[Study of radiation dose rate in air at Setagaya in Tokyo].  

Science.gov (United States)

The great earthquake occurred at East Japan on March 11, 2011 and the following tsunami induced the accident which environmentally leaked radioactive materials from the nuclear power plant of the Fukushima Daiichi. We measured radiation dose rate in air by the NaI (Tl) scintillation and GM survey meters from March 15 to May 30 at Setagaya in Tokyo. Three measured points were at the 1m height from the ground on asphalt surfaced road, at the 5cm height from ground with weeds, and at the room of a reinforced concrete building. As a result, a transient increase was observed on March 15, a sustained rise was observed on both days of March 21 and 22. The latter was thought to be due to the radioactive rainfall. These measured values were compared with the radiation dose rate in air of the cities in Kanto area, and it was confirmed that the measured values at Setagaya are not so different from that of those cities. PMID:22259853

Hachisuka, Akiko; Kimura, Yoshie; Nakamura, Ryosuke; Teshima, Reiko

2011-01-01

278

Quality assurance for radon exposure chambers at the National Air and Radiation Environmental Laboratory, Montgomery, Alabama  

Energy Technology Data Exchange (ETDEWEB)

The Office of Radiation and Indoor Air, U.S. Environmental Protection Agency (EPA), operates six radon exposure chambers in its two laboratories, the National Air and Radiation Environmental Laboratory (NAREL) in Montgomery, Alabama, and the Las Vegas Facility, Las Vegas, Nevada. These radon exposure chambers are used to calibrate and test portable radon measuring instruments, test commercial suppliers of radon measurement services through the Radon Measurement Proficiency Program, and expose passive measurement devices to known radon concentrations as part of a quality assurance plan for federal and state studies measuring indoor radon concentrations. Both laboratories participate in national and international intercomparisons for the measurement of radon and are presently working with the National Institute of Standards and Technology (NIST) to receive a certificate of traceability for radon measurements. NAREL has developed an estimate of the total error in its calibration of each chamber`s continuous monitors as part of an internal quality assurance program. This paper discusses the continuous monitors and their calibration for the three chambers located in Montgomery, Alabama, as well as the results of the authors intercomparisons and total error analysis.

Semler, M.O.; Sensintaffar, E.L. [National Air and Radiation Environmental Laboratory, Montgomery, AL (United States)

1993-12-31

279

An Earth longwave radiation climate model  

Science.gov (United States)

An Earth outgoing longwave radiation (OLWR) climate model was constructed for radiation budget study. Required information is provided by on empirical 100mb water vapor mixing ratio equation of the mixing ratio interpolation scheme. Cloud top temperature is adjusted so that the calculation would agree with NOAA scanning radiometer measurements. Both clear sky and cloudy sky cases are calculated and discussed for global average, zonal average and world-wide distributed cases. The results agree well with the satellite observations. The clear sky case shows that the OLWR field is highly modulated by water vapor, especially in the tropics. The strongest longitudinal variation occurs in the tropics. This variation can be mostly explained by the strong water vapor gradient. Although in the zonal average case the tropics have a minimum in OLWR, the minimum is essentially contributed by a few very low flux regions, such as the Amazon, Indonesian and the Congo.

Yang, S. K.

1984-01-01

280

ANALYTICAL DIFFUSION MODEL FOR LONG DISTANCE TRANSPORT OF AIR POLLUTANTS  

Science.gov (United States)

A steady-state two-dimensional diffusion model suitable for predicting ambient air pollutant concentrations averaged over a long time period (e.g., month, season, or year) and resulting from the transport of pollutants for distances greater than about 100 km from the source is de...

281

Discontinuous Galerkin Method for the Air Pollution Model  

OpenAIRE

In this paper we present the discontinuous Galerkin method to solve the problem of the two-dimensional air pollution model. The resulting system of ordinary differential equations is called the semidiscrete formulation. We show the existence and uniqueness of the ODE system and provide the error estimates for the numerical error.

Xijian Wang; Lite Zhao

2013-01-01

282

Discontinuous Galerkin Method for the Air Pollution Model  

CERN Document Server

In this paper we present the discontinuous Galerkin method to solve the problem of the two-dimensional air pollution model. The resulting system of ordinary differential equations is called the semidiscrete formulation. We show the existence and uniqueness of the ODE system and provide the error estimates for the numerical error.

Zhao, Lite; Hou, Qinzhi

2011-01-01

283

Radiolytic yield of ozone in air for low dose neutron and x-ray/gamma-ray radiation  

Science.gov (United States)

Radiation ionizes surrounding air and produces molecular species, and these localized effects may be used as a signature of, and for quantification of, radiation. Low-level ozone production measurements from radioactive sources have been performed in this work to understand radiation chemical yields at low doses. The University of New Mexico AGN-201 M reactor was used as a tunable radiation source. Ozone levels were compared between reactor-on and reactor-off conditions, and differences (0.61 to 0.73 ppb) well below background levels were measured. Simulations were performed to determine the dose rate distribution and average dose rate to the air sample within the reactor, giving 35 mGy of mixed photon and neutron dose. A radiation chemical yield for ozone of 6.5±0.8 molecules/100 eV was found by a variance weighted average of the data. The different contributions of photons and neutrons to radiolytic ozone production are discussed.

Cole, J.; Su, S.; Blakeley, R. E.; Koonath, P.; Hecht, A. A.

2015-01-01

284

Long-term patterns in dissolved organic carbon in boreal lakes: the role of incident radiation, precipitation, air temperature, southern oscillation and acid deposition  

Directory of Open Access Journals (Sweden)

Full Text Available Both lake-specific (e.g. pH and regional (e.g. precipitation factors affect DOC concentration and pattern. Using annual DOC concentration in nine boreal lakes in the ice-free season, the potential influences of five regional factors, air temperature, precipitation, SO4 deposition, solar radiation (photosynthetically active radiation, or PAR and the southern oscillation index (SOI have been explored through multiple regression. Mean solar radiation, winter precipitation and summer precipitation explained 59% of the variation in the mean DOC concentration (F3,17= 8.29, p= 0.0013. Solar radiation and winter precipitation were correlated, negatively, while summer precipitation was correlated, positively, with DOC concentration. Because these relationships were based on only 21 years of data (1978 to 1998, the significance of the parameters in the regression model was evaluated with a randomisation test. This re-analysis indicated that summer precipitation did not contribute significantly to the regression model ( prand= 0.183. The final multiple regression explained 50% of the variation in DOC (F2,18 = 9.33, prand= 0.002 based on solar radiation and winter precipitation. These results suggest that solar radiation and winter precipitation have a significant role in determining long-term DOC concentration in boreal lakes. Keywords: dissolved-organic-carbon, lakes, climate, solar-radiation, precipitation, acid-precipitation, Precambrian-Shield-Ontario

J. J. Hudson

2003-01-01

285

Solar radiation practical modeling for renewable energy applications  

CERN Document Server

Written by a leading scientist with over 35 years of experience working at the National Renewable Energy Laboratory (NREL), Solar Radiation: Practical Modeling for Renewable Energy Applications brings together the most widely used, easily implemented concepts and models for estimating broadband and spectral solar radiation data. The author addresses various technical and practical questions about the accuracy of solar radiation measurements and modeling. While the focus is on engineering models and results, the book does review the fundamentals of solar radiation modeling and solar radiation m

Myers, Daryl Ronald

2013-01-01

286

Linkage between an advanced air quality model and a mechanistic watershed model  

OpenAIRE

An offline linkage between two advanced multi-pollutant air quality and watershed models is presented. The models linked are (1) the Advanced Modeling System for Transport, Emissions, Reactions and Deposition of Atmospheric Matter (AMSTERDAM) (a three-dimensional Eulerian plume-in-grid model derived from the Community Multiscale Air Quality (CMAQ) model) and (2) the Watershed Analysis Risk Management Framework (WARMF). The pollutants linked include gaseous and particulate nitrogen, sulfur and...

Vijayaraghavan, K.; Herr, J.; -y Chen, S.; Knipping, E.

2010-01-01

287

Development and Evaluation of Global Solar Radiation Models Based on Sunshine Hours and Meteorological Data  

Directory of Open Access Journals (Sweden)

Full Text Available Global solar radiation (Rs has wide applications in several disciplines. The data of measured or predicted Rs are widely applied by solar engineers, architects, agriculturists and hydrologists. Due to the importance of Rs, several empirical models have been developed to predict its values all over the world. In this study, Angstrom model was calibrated based on the ratio of actual and possible sunshine hours n/N by using measured daily data of Rs at Bajghah meteorological station in Fars province during 2003-2004. The model was modified by using air temperature for considering the effect of cloudy conditions as well as n/N ratios. The results showed that using both the air temperatures and the ratios of n/N led to a higher accuracy. In regard to estimation of the Rs values, the results showed that mean air temperatures have a higher accuracy compared with differences between maximum and minimum air temperatures. Also, a new local model with higher accuracy was developed based on a number of daily meteorological parameters such as deficit vapor pressure, relative humidity, precipitation, mean air temperature, maximum and minimum air temperatures difference and n/N. This new local model that used different meteorological parameters had the highest accuracy in comparison with the other models. Also, a number of models developed by other investigators for estimation of Rs were calibrated for the study area. Finally, different selected models were validated by using the measured data of Rs in 2005. The results showed that the developed local multi-variable model provided higher accuracy results in comparison with the other radiation models.

A Majnoni-Heris

2009-01-01

288

A backward-time stochastic Lagrangian air quality model  

Science.gov (United States)

We describe a backward-time Lagrangian air quality model based on time-reversed, stochastic particle trajectories. The model simulates the transport of air parcels backward in time using ensembles of fictitious particles with stochastic motions generated from the Stochastic Time-Inverted Lagrangian Transport model (STILT). Due to the fact that STILT was originally developed out of the HYSPLIT lineage, the model leverages previous work (Stein et al., 2000) that implemented within HYSPLIT a chemical scheme (CB4). Chemical transformations according to the CB4 scheme are calculated along trajectories identified by the backward-time simulations. This approach opens up several key advantages: 1) exclusive focus upon air parcels that affect the receptor's air quality; 2) the separation of transport processes—elucidated by backward-time trajectories—from chemical reactions that enables implications of multiple emission scenarios to be probed; 3) the potential to incorporate detailed sub-gridscale mixing and transport phenomena that are not tied to Eulerian gridcells. The model was used to simulate concentrations of air quality-relevant species (O3 and NOx) at eight measurement sites in the Canadian province of Ontario. The model-predicted concentrations were compared with observations, and comparisons show that simulated O3 concentrations usually agree well with observations across sites in rural areas, small towns, and big urban regions. Furthermore, the backward-time model showed improved performance over the previous approach involving forward-time particle trajectories, especially for O3. However, the model under-estimated NOx at sites away from the big cities, possibly due to the inability of the coarsely gridded emission grids to resolve fine-scale NOx sources. Influences of cross-border transport of U.S. emission sources on the test sites were investigated using the model by turning off anthropogenic and natural U.S. emission sources. The model results suggest that total U.S. emissions contributed more than 30% of O3 concentrations at the target sites and that over half of all hours during the simulation period were affected either by anthropogenic or natural emissions from the U.S. sources, indicating the importance of U.S. sources for air quality across Ontario.

Wen, Deyong; Lin, John C.; Millet, Dylan B.; Stein, Ariel F.; Draxler, Roland R.

2012-07-01

289

Air quality along motorways. Measuring and modelling calculations  

International Nuclear Information System (INIS)

This report describes the air quality along Koege Bugt motorway, one of the most trafficked sections in Denmark. A number of measurements have been carried out along Koege Bugt motorway at Greve for a three-month period in the autumn of 2003. For the first time in Denmark, NOx were measured with high time dissolution from different distances of the motorway. Furthermore, a number of meteorological parameters were measured in order to map local meteorological conditions. An air quality model describing dispersal and conversion has been made on the basis of the OML model. The OML model is modified in order to take traffic-made turbulence into consideration. The model has been evaluated through comparisons between measurements and simulated calculations. Furthermore, simulated calculations for the year 2003 has been made for comparison with extreme values. (BA)

290

Study of radiation-induced modification of FEP in nitrogen and air atmospheres  

International Nuclear Information System (INIS)

Fluoropolymers are a class of polymer with specific characteristics like chemical inertia and stability under aggressive chemical environmental. These properties are a consequence of the chemical structure, C-F bonds. Poli (tetrafluoroethylene-co-hexafluoropropylene) (FEP) is inserting in these class of polymer. FEP has good chemical and physical resistance, its working in temperature of 200 degree C and has a surface extremely smooth. This polymer is used as component in films, coatings, tapes, wires and cables in a variety of industries including telecommunications, semiconductor, chemical, food processing and packaging. In this study was used film with 100mm of thickness that were submitted to gamma radiation under nitrogen and air atmospheres in order to observe the effect of atmosphere in the polymer matrix. The irradiated doses were: 5, 10, 20, 40 and 80kGy at room temperature. The characterization was made by thermogravimetric analysis (TG), scanning electron microscope (SEM) and infrared spectroscopy using attenuate reflectance (ATR-IR). The TG analysis shown two degradation steps and for the samples irradiated under air the initial degradation began 10 degrees earlier than the samples irradiated under nitrogen. After the analysis, the results obtained were expected: the degradation reactions occurred in the samples irradiated under air atmosphere and the film has no changes in the structure when was irradiated under nitrogen atmosphere. (author)

291

Asian Dust particles impacts on air quality and radiative forcing over Korea  

International Nuclear Information System (INIS)

Asian Dust particles originated from the deserts and loess areas of the Asian continent are often transported over Korea, Japan, and the North Pacific Ocean during spring season. Major air mass pathway of Asian dust storm to Korea is from either north-western Chinese desert regions or north-eastern Chinese sandy areas. The local atmospheric environment condition in Korea is greatly impacted by Asian dust particles transported by prevailing westerly wind. Since these Asian dust particles pass through heavily populated urban and industrial areas in China before it reach Korean peninsular, their physical, chemical and optical properties vary depending on the atmospheric conditions and air mass pathway characteristics. An integrated system approach has been adopted at the Advanced Environment Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosols utilizing various in-situ and optical remote sensing methods, which include a multi-channel Raman LIDAR system, sunphotometer, satellite, and in-situ instruments. Results from recent studies on impacts of Asian dust particles on local air quality and radiative forcing over Korea are summarized here.

292

Study of radiation-induced modification of FEP in nitrogen and air atmospheres  

Energy Technology Data Exchange (ETDEWEB)

Fluoropolymers are a class of polymer with specific characteristics like chemical inertia and stability under aggressive chemical environmental. These properties are a consequence of the chemical structure, C-F bonds. Poli (tetrafluoroethylene-co-hexafluoropropylene) (FEP) is inserting in these class of polymer. FEP has good chemical and physical resistance, its working in temperature of 200 degree C and has a surface extremely smooth. This polymer is used as component in films, coatings, tapes, wires and cables in a variety of industries including telecommunications, semiconductor, chemical, food processing and packaging. In this study was used film with 100mm of thickness that were submitted to gamma radiation under nitrogen and air atmospheres in order to observe the effect of atmosphere in the polymer matrix. The irradiated doses were: 5, 10, 20, 40 and 80kGy at room temperature. The characterization was made by thermogravimetric analysis (TG), scanning electron microscope (SEM) and infrared spectroscopy using attenuate reflectance (ATR-IR). The TG analysis shown two degradation steps and for the samples irradiated under air the initial degradation began 10 degrees earlier than the samples irradiated under nitrogen. After the analysis, the results obtained were expected: the degradation reactions occurred in the samples irradiated under air atmosphere and the film has no changes in the structure when was irradiated under nitrogen atmosphere. (author)

Souza, Camila P.; Zen, Heloisa A.; Lugao, Ademar B., E-mail: helozen@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

293

Surface air temperature variability in global climate models  

CERN Document Server

New results from the Coupled Model Inter-comparison Project phase 5 (CMIP5) and multiple global reanalysis datasets are used to investigate the relationship between the mean and standard deviation in the surface air temperature. A combination of a land-sea mask and orographic filter were used to investigate the geographic region with the strongest correlation and in all cases this was found to be for low-lying over-land locations. This result is consistent with the expectation that differences in the effective heat capacity of the atmosphere are an important factor in determining the surface air temperature response to forcing.

Davy, Richard

2012-01-01

294

Plutonium air transportable package Model PAT-1. Safety analysis report  

International Nuclear Information System (INIS)

The document is a Safety Analysis Report for the Plutonium Air Transportable Package, Model PAT-1, which was developed by Sandia Laboratories under contract to the Nuclear Regulatory Commission (NRC). The document describes the engineering tests and evaluations that the NRC staff used as a basis to determine that the package design meets the requirements specified in the NRC ''Qualification Criteria to Certify a Package for Air Transport of Plutonium'' (NUREG-0360). By virtue of its ability to meet the NRC Qualification Criteria, the package design is capable of safely withstanding severe aircraft accidents. The document also includes engineering drawings and specifications for the package. 92 figs, 29 tables

295

Modelling of an Air Compressor Using Energetic Macroscopic Representation  

OpenAIRE

This article introduces the energetic macroscopic representation (EMR) as approach for the dynamic nonlinear modeling of a reciprocating air compressor. EMR has been introduced recently for research development in complex electromechanical systems. It is based on action reaction principle, which organizes the system as interconnected subsystems according to the integral causality. The graphical modeling based on EMR has advantages such as readability, modularity, structural and functional cha...

Heidari, Mahbod; Tsirinomeney, Martel; Rufer, Alfred; Barrade, Philippe

2012-01-01

296

Air pollution dispersion models for human exposure predictions in London.  

Science.gov (United States)

The London household survey has shown that people travel and are exposed to air pollutants differently. This argues for human exposure to be based upon space-time-activity data and spatio-temporal air quality predictions. For the latter, we have demonstrated the role that dispersion models can play by using two complimentary models, KCLurban, which gives source apportionment information, and Community Multi-scale Air Quality Model (CMAQ)-urban, which predicts hourly air quality. The KCLurban model is in close agreement with observations of NO(X), NO(2) and particulate matter (PM)(10/2.5), having a small normalised mean bias (-6% to 4%) and a large Index of Agreement (0.71-0.88). The temporal trends of NO(X) from the CMAQ-urban model are also in reasonable agreement with observations. Spatially, NO(2) predictions show that within 10's of metres of major roads, concentrations can range from approximately 10-20 p.p.b. up to 70 p.p.b. and that for PM(10/2.5) central London roadside concentrations are approximately double the suburban background concentrations. Exposure to different PM sources is important and we predict that brake wear-related PM(10) concentrations are approximately eight times greater near major roads than at suburban background locations. Temporally, we have shown that average NO(X) concentrations close to roads can range by a factor of approximately six between the early morning minimum and morning rush hour maximum periods. These results present strong arguments for the hybrid exposure model under development at King's and, in future, for in-building models and a model for the London Underground. PMID:23443237

Beevers, Sean D; Kitwiroon, Nutthida; Williams, Martin L; Kelly, Frank J; Ross Anderson, H; Carslaw, David C

2013-01-01

297

Modeling of air pollution from the power plant ash dumps  

Science.gov (United States)

A simple model of air pollution from power plant ash dumps is presented, with emission rates calculated from the Bagnold formula and transport simulated by the ATDL type model. Moisture effects are accounted for by assumption that there is no pollution on rain days. Annual mean daily sedimentation rates, calculated for the area around the 'Nikola Tesla' power plants near Belgrade for 1987, show reasonably good agreement with observations.

Aleksic, Nenad M.; Bala?, Nedeljko

298

Air quality over Europe: modelling gaseous and particulate pollutants  

OpenAIRE

Air quality over Europe using Models-3 (i.e., CMAQ, MM5, SMOKE) modelling system is performed for winter (i.e., January 2006) and summer (i.e., July 2006) months with the 2006 TNO gridded anthropogenic emissions database. Higher ozone mixing ratios are predicted in southern Europe while higher NO2 levels are simulated over western Europe. Elevated SO2 values are simulated over eastern Europe and higher PM2.5 concentrations over eastern and western Europe. Regi...

Tagaris, E.; Sotiropoulou, R. E. P.; Gounaris, N.; Andronopoulos, S.; Vlachogiannis, D.

2013-01-01

299

Spatio-temporal modeling and forecasting of air quality data  

OpenAIRE

Respirable Suspended Particulate (RSP) time series data sampled in an air quality monitoring network are found strongly correlated and they are varying in highly similar patterns. This study provides a methodology for spatio-temporal modeling and forecasting of multiple RSP time series, in which the dynamic spatial correlations amongst the series can be effectively utilized. ??The efficacy of the Spatio-Temporal Dynamic Harmonic Regression (STDHR) model is demonstrated. Based on the d...

Yan, Tsz-leung; ???

2014-01-01

300

Two dimensional model for coherent synchrotron radiation  

Science.gov (United States)

Understanding coherent synchrotron radiation (CSR) effects in a bunch compressor requires an accurate model accounting for the realistic beam shape and parameters. We extend the well-known 1D CSR analytic model into two dimensions and develop a simple numerical model based on the Liénard-Wiechert formula for the CSR field of a coasting beam. This CSR numerical model includes the 2D spatial dependence of the field in the bending plane and is accurate for arbitrary beam energy. It also removes the singularity in the space charge field calculation present in a 1D model. Good agreement is obtained with 1D CSR analytic result for free electron laser (FEL) related beam parameters but it can also give a more accurate result for low-energy/large spot size beams and off-axis/transient fields. This 2D CSR model can be used for understanding the limitation of various 1D models and for benchmarking fully electromagnetic multidimensional particle-in-cell simulations for self-consistent CSR modeling.

Huang, Chengkun; Kwan, Thomas J. T.; Carlsten, Bruce E.

2013-01-01

301

Alpha and gamma radiation effects on air-water systems at high gas/liquid ratios  

International Nuclear Information System (INIS)

Radiolysis tests were conducted on air-water systems to examine the effects of radiation on liquid phase chemistry under high gas/liquid volume (G/L) ratios that are characteristic of an unsaturated nuclear waste repository setting. Test parameters included temperatures of 25, 90, and 200 degrees C; gamma vs. alpha radiation; dose rates of ?3500 and 50,000 rad/h; and G/L ratios of 10 and 100. Formate, oxalate, and total organic carbon contents increased during irradiation of the air-water systems in gamma and alpha tests at low-dose rate (?3500 rad/h). Increases in organic components were not observed for tests run at 200 degrees C or high-dose rates (50,000 rad/h). In the tests where increases in organics occurred, the formate and oxalate were preferentially enriched in solutions that were rinsed from the test vessel walls. Nitrate (NO3-) is the dominant anion produced during the radiolysis reactions. Significant nitrite (NO2-) also occurs in some high-dose rate tests, with the reduced form of nitrogen possibly resulting from reactions with the test vessels. These results indicate that nitrogen acids are being produced and concentrated in the limited quantities of solution present in the tests. Nitrate + nitrite production varied inversely with temperature, with the lowest quantities being detected for the higher temperature tests. The G(NO3- + NO2-) values for the 25, 90, and 200 degrees C experiments with gamma radiation are 3.2 ± 0.7, 1.3 ± 1.0, and 0.4 ± 0.3, respectively. Thus, the elevated temperatures expected early in the life of a repository may counteract pH decreases resulting from nitrogen acid production. Little variation was observed in G values as a function of dose rate or gas/liquid ratio

302

Measurement and Modeling of Particle Radiation in Coal Flames  

DEFF Research Database (Denmark)

This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite flame. Spectral radiation, total radiative intensity, gas temperature, and gas composition were measured, and the radiative intensity in the furnace was modeled with an axisymmetric cylindrical radiation model using Mie theory for the particle properties and a statistical narrow-band model for the gas properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information about particle radiation and temperature, the methodology can also provide estimates of the amount of soot radiation and the maximum contribution from soot radiation compared to the total particle radiation. In the center position in the flame, the maximum contribution from soot radiation was estimated to be less than 40% of the particle radiation. As a validation of the methodology, the modeled total radiative intensity was compared to the total intensity measured with a narrow angle radiometer and the agreement in the results was good, supporting the validity of the used approach.

Ba?ckstro?m, Daniel; Johansson, Robert

2014-01-01

303

ESTUDIO NUMÉRICO Y EXPERIMENTAL DE LAS PROPIEDADES Y FENÓMENOS RADIATIVOS EN UNA LLAMA DE METANO (CH4) CON AIRE ENRIQUECIDO / NUMERICAL AND EXPERIMENTAL STUDY OF THE RADIATIVE PROPERTIES AND PHENOMENA IN A METHANE (CH4) FLAME WITH ENRICHED AIR  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish En este artículo, se presenta un estudio numérico y experimental del comportamiento de la radiación de una llama de metano con aire enriquecido con bajas concentraciones oxígeno. Se midió el flux de calor por radiación y se determinó su relación con el porcentaje de enriquecimiento del aire, permiti [...] endo estimar las propiedades radiantes de la llama en función del enriquecimiento con oxígeno. Se utilizó aire con concentraciones de oxígeno desde 21% hasta 22,5%. La simulación se realizó con el software Fluent V6.2.16 y para resolver la ecuación de transferencia radiativa se empleó el modelo de las Ordenadas Discretas. Las propiedades radiantes de la mezcla de gases de combustión (CO, CO2 y H2O) se cuantificaron empleando el modelo de la Suma Ponderada de Gases Grises (WSGGM). La experimentación se llevó a cabo empleando como combustible Gas Natural de la Guajira, un factor de aireación de 1,1 y una potencia térmica de 1,54 kW. Se utilizó un quemador de premezcla tipo Bunsen, en el que se inducía el aire, el cual a su vez es enriquecido con oxígeno proveniente de un cilindro. Abstract in english This article proposes a numerical and experimental study of the radiation behavior in a methane flame with air enhanced with oxygen at low concentrations. It was measured the heat flux by radiation and was determined its relationship with the percentage of enrichment of the air, which allowed to est [...] imate the radiant properties of the flame in terms of oxygen enrichment. Was used air with oxygen concentrations from 21% to 22,5%. The simulation was done with the software Fluent V6.2.16 and to solve the radiative transfer equation was used the Discrete Ordinates model. The radiant properties of the mixture of combustion gases (CO, CO2 and H2O) were quantified using the Weighted Sum of Gray Gases Model (WSGGM). The experiment was carried out using Guajira Natural Gas as fuel, an air factor equal to 1,1 and a thermal power of 1,54 kW.

JOSE LUIS, SUÁREZ; ANDRÉS AMELL, ARRIETA; FRANCISCO JAVIER, CADAVID.

2011-02-01

304

A 331 WIMPy Dark Radiation Model  

CERN Document Server

Recent observations suggest that the number of relativistic degrees of freedom in the early universe might exceed what predicted in the standard cosmological model. If even a small, percent-level fraction of dark matter particles are produced relativistically, they could mimic the effect of an extra realistic species at matter-radiation equality while obeying BBN, CMB and Structure Formation bounds. We show that this scenario is quite naturally realized with a weak-scale dark matter particle and a high-scale "mother" particle within a well motivated 3-3-1 gauge model, which is particularly interesting for being consistent with electroweak precision measurements, with recent LHC results, and for offering a convincing explanation for the number of generations in the Standard Model.

Kelso, Chris; Profumo, Stefano; Queiroz, Farinaldo S; da Silva, P S Rodrigues

2013-01-01

305

A 331 WIMPy dark radiation model  

Energy Technology Data Exchange (ETDEWEB)

Recent observations suggest that the number of relativistic degrees of freedom in the early universe might exceed what is predicted in the standard cosmological model. If even a small, percent-level fraction of dark matter particles are produced relativistically, they could mimic the effect of an extra realistic species at matter-radiation equality while obeying BBN, CMB and Structure Formation bounds. We show that this scenario is quite naturally realized with a weak-scale dark matter particle and a high-scale ''mother'' particle within a well-motivated 3-3-1 gauge model, which is particularly interesting for being consistent with electroweak precision measurements, with recent LHC results, and for offering a convincing explanation for the number of generations in the Standard Model. (orig.)

Kelso, Chris [University of Utah, Department of Physics and Astronomy, Salt Lake City, UT (United States); Pires, C.A. de S.; Rodrigues da Silva, P.S. [Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil); Profumo, Stefano; Queiroz, Farinaldo S. [University of California, Department of Physics and Santa Cruz Institute for Particle Physics, Santa Cruz, CA (United States)

2014-03-15

306

Air filled ionization chambers and their response to high LET radiation  

DEFF Research Database (Denmark)

Background Air filled ionization chambers (ICs) are widely used for absolute dosimetry, not only in photon beams but also in beams of heavy charged particles. Within the IC, electron hole pairs are generated by the energy deposition originating from incoming radiation. High-LET particles create a high density of charge carriers in the core of particle tracks. As a consequence an increased (so called "initial") recombination of the charge carriers takes place, besides of the general (volume) recombination described by the Boag theory. A theory for a sub-type of initial recombination ("columnar" recombination) is the Jaffe theory, which was developed in 1913 by Jaffe. He solved a differential equation by applying several simplifications and approximations such as a Gaussian shaped track whose width serves as free parameter. These simplifications and the use of an simplified charge carrier distribution are leading to discrepancies between theory and experiments. Material and Methods We solved the fundamental differential equation presented by Jaffe numerically, taking into account both diffusion and recombination terms and realistic models of the initial charge carrier distribution developed by track structure theory. More specifically, we solved the equation for the geometrical setup of the Bragg-peak IC, which is a plane parallel IC with a 2 mm spacing between the electrodes. The sensitive volume of the IC is located in a thermoplastic housing of several mm thickness. Results We compare the experimental results of the collection efficiency of the Bragg peak IC to both the Jaffe theory and to our numerical solution of the diffusion recombination equation. Fitting a Jaffe curve to the measured collection efficiency resulted in values comparable to the literature. Calculations assuming radial dose distributions coming from track structure require long computation times, caused by the high spatial resolution and the subsequent requirements to temporal resolution. Conclusion Our numerical solution of the diffusion recombination assuming a Gaussian beam shape is relatively well described by the Jaffe theory. Additionally, preliminary results show that that the calculated response does not depend on the core radius of the radial dose distribution. References JAFFE, G.C:  On the theory of columnar recombination.  Annalen der Physik.  42, 303-344, 1913. KANAI, T. et al.: Initial recombination in a parallel-plate ionization chamber exposed to heavy ions Phys. Med. Biol. 43 3549–58, 1998. ELSAESSER, T. et al.: Impact of track structure on biological treatment planning ion ion radiotherapy. New Journal pf Physics 10. 075005, 2008

Kaiser, Franz-Joachim; Bassler, Niels

307

Model-based parameterisation of a hydrocyclone air-core  

Science.gov (United States)

An important metric for the accurate control of a hydrocyclone is the diameter of its air-core. Ultrasonic data from a 16-transducer, 1.5 MHz pulse-echo tomographic system are analysed to determine the variation of the air-core diameter with various operating conditions. The back-projection image reconstruction method is not accurate enough for this task. Sub-millimetre accuracy is obtained, however, by applying a combination of signal processing and model-based reconstruction, using the fact that there is a small variation in the air-core boundary position. The findings correspond well to the results obtained from X-ray and electrical resistance modalities. PMID:10829775

Podd; Schlaberg; Hoyle

2000-03-01

308

Solutions Network Formulation Report. NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation and Increasing Air Quality  

Science.gov (United States)

This Candidate Solution is based on using NASA Earth science research on atmospheric ozone and aerosols data as a means to predict and evaluate the effectiveness of photocatalytically created surfaces (building materials like glass, tile and cement) for air pollution mitigation purposes. When these surfaces are exposed to near UV light, organic molecules, like air pollutants and smog precursors, will degrade into environmentally friendly compounds. U.S. EPA (Environmental Protection Agency) is responsible for forecasting daily air quality by using the Air Quality Index (AQI) that is provided by AIRNow. EPA is partnered with AIRNow and is responsible for calculating the AQI for five major air pollutants that are regulated by the Clean Air Act. In this Solution, UV irradiance data acquired from the satellite mission Aura and the OMI Surface UV algorithm will be used to help understand both the efficacy and efficiency of the photocatalytic decomposition process these surfaces facilitate, and their ability to reduce air pollutants. Prediction models that estimate photocatalytic function do not exist. NASA UV irradiance data will enable this capability, so that air quality agencies that are run by state and local officials can develop and implement programs that utilize photocatalysis for urban air pollution control and, enable them to make effective decisions about air pollution protection programs.

Underwood, Lauren; Ryan, Robert E.

2007-01-01

309

LANL*: Radiation belt drift shell modeling  

Science.gov (United States)

LANL* calculates the magnetic drift invariant L*, used for modeling radiation belt dynamics and other space weather applications, six orders of magnitude (~ one million times) faster than convectional approaches that require global numerical field lines tracing and integration. It is based on a modern machine learning technique (feed-forward artificial neural network) by supervising a large data pool obtained from the IRBEM library, which is the traditional source for numerically calculating the L* values. The pool consists of about 100,000 samples randomly distributed within the magnetosphere (r: [1.03, 11.5] Re) and within a whole solar cycle from 1/1/1994 to 1/1/2005. There are seven LANL* models, each corresponding to its underlying magnetic field configuration that is used to create the data sample pool. This model has applications to real-time radiation belt forecasting, analysis of data sets involving tens of satellite-years of observations, and other problems in space weather.

Yu, Yiqun; Koller, Josef

2014-09-01

310

Biological models in epidemiology: radiation carcinogenesis  

International Nuclear Information System (INIS)

The status of ionizing radiation as one of the common environmental causes of cancer is introduced. Relying on the considerable body of theoretical and experimental radiobiology to provide a theoretical framework and the basic scientific principle of consistency or results among different populations, differently exposed, the validity of objections is considered. First radiobiological theory and then the studies of the Japanese A-Bomb survivors are presented, the latter in detail with tables of measurements. Final discussion suggests applications and future study needed and eventually refined estimates of risk when new models are applied to epidemiological data

311

Indicators to support the dynamic evaluation of air quality models  

Science.gov (United States)

Air quality models are useful tools for the assessment and forecast of pollutant concentrations in the atmosphere. Most of the evaluation process relies on the “operational phase” or in other words the comparison of model results with available measurements which provides insight on the model capability to reproduce measured concentrations for a given application. But one of the key advantages of air quality models lies in their ability to assess the impact of precursor emission reductions on air quality levels. Models are then used in a dynamic mode (i.e. response to a change in a given model input data) for which evaluation of the model performances becomes a challenge. The objective of this work is to propose common indicators and diagrams to facilitate the understanding of model responses to emission changes when models are to be used for policy support. These indicators are shown to be useful to retrieve information on the magnitude of the locally produced impacts of emission reductions on concentrations with respect to the “external to the domain” contribution but also to identify, distinguish and quantify impacts arising from different factors (different precursors). In addition information about the robustness of the model results is provided. As such these indicators might reveal useful as first screening methodology to identify the feasibility of a given action as well as to prioritize the factors on which to act for an increased efficiency. Finally all indicators are made dimensionless to facilitate the comparison of results obtained with different models, different resolutions, or on different geographical areas.

Thunis, P.; Clappier, A.

2014-12-01

312

Modeling a Rocket Launch with Gravity and Air Resistance  

Science.gov (United States)

The Modeling a Rocket Launch with Gravity and Air Resistance text guides the reader through a process of developing, implementing, and validating an EJS model of a rocket being launched. The model that is developed includes thrust as well as altitude-dependent forces of gravity and air resistance. The supplementary documents include a starting template (RocketTemplate.ejs), an executable JAR file in which all three forces have been implemented (RocketLaunch.jar), and a document describing how and why to use âEventsâ in Ejs. Note, a password will be required in order to access the EJS source code for the completed (RocketLaunch.jar) program. A faculty member wishing to access this may request the password from lengelhardt@fmarion.edu.

Engelhardt, Larry

2011-07-03

313

The direct and inverse problems of an air-saturated poroelastic cylinder submitted to acoustic radiation  

OpenAIRE

A wave-fluid saturated poroelastic structure interaction model based on the modified Biot theory (MBT) and plane-wave decomposition using orthogonal cylindrical functions is developed. The model is employed to recover from real data acquired in an anechoic chamber, the poromechanical properties of a soft cellular melamine cylinder submitted to an audible acoustic radiation. The inverse problem of acoustic diffraction is solved by constructing the objective functional given by the total square...

Erick Ogam; Fellah, Z. E. A.

2011-01-01

314

Impacts of contaminant storage on indoor air quality: Model development  

Science.gov (United States)

A first-order, lumped capacitance model is used to describe the buffering of airborne chemical species by building materials and furnishings in the indoor environment. The model is applied to describe the interaction between formaldehyde in building materials and the concentration of the species in the indoor air. Storage buffering can decrease the effect of ventilation on the indoor concentration, compared to the inverse dependence of indoor concentration on the air exchange rate that is consistent with a constant emission rate source. If the exposure time of an occupant is long relative to the timescale of depletion of the compound from the storage medium, however, the total exposure will depend inversely on the air exchange rate. This lumped capacitance model is also applied to moisture buffering in the indoor environment, which occurs over much shorter depletion timescales of the order of days. This model provides a framework to interpret the impact of storage buffering on time-varying concentrations of chemical species and resulting occupant exposure. Pseudo-steady-state behavior is validated using field measurements. Model behavior over longer times is consistent with formaldehyde and moisture concentration measurements in previous studies.

Sherman, Max H.; Hult, Erin L.

2013-06-01

315

Critical ingredients of supernova Ia radiative-transfer modeling  

OpenAIRE

We explore the physics of SN Ia light curves and spectra using the 1-D non-LTE time-dependent radiative-transfer code CMFGEN. Rather than adjusting ejecta properties to match observations, we select as input one "standard" 1-D Chandrasekhar-mass delayed-detonation hydrodynamical model, and then explore the sensitivity of radiation and gas properties on radiative-transfer modeling assumptions. The correct computation of SN Ia radiation is not exclusively a solution to an "opa...

Dessart, Luc; Hillier, D. John; Blondin, Stephane; Khokhlov, Alexei

2013-01-01

316

Measured, modelled and satellite derived solar radiation in Scandinavia  

OpenAIRE

This article presents a comparison of global radiation data at different sites at the Scandinavian Peninsula. It makes use of ground truth, modelled and satellite derived surface global radiation data. First, a quality control of the ground truth data is conducted by evaluating measurements against the clear sky radiation estimated by a reliable model. Second, global radiation data derived from the geostationary satellite Meteosat are compared to the ground truth data.

Hagen, Linda

2011-01-01

317

Radiation creep model, considering dislocation slip and climb an obstacle  

International Nuclear Information System (INIS)

A generalized model of radiation creep based on edge dislocation slip and climb is described. A formula is deduced. It helps to obtain, as an individual case, expressions for radiation creep velocity, presented by the known before SIPA, SIAD, Gittus-Mansur, slip-climb models. Dependences of radiation creep on temperature, stress, radiation dose are calculated; comparison with the corresponding experimental data for reactor steels is carried out

318

Search for molecular bremsstrahlung radiation signals in Ku band with coincidental operations of radio telescopes with air shower detectors  

OpenAIRE

Microwave radiation from extensive air showers is expected to provide a new technique to observe UHECR. We insatlled and operate radio telescopes in Osaka and at Telescope Array site in Utah, USA. In Osaka, we are coincidentally operating two Ku band radio telescopes with an air shower array which consists of nine plastic scintillators with about 10?m separation. In Utah, we installed two telescopes just beside the Black Rock Mesa fluorescence detector (FD) station of the Telescope Array ex...

Fukushima Masaki; Sakurai Nobuyuki; Fujii Toshihiro; Akimune Hidetoshi; Iijima Takashi; Kuramoto Kazuyuki; Yamamoto Tokonatsu; Ogio Shoichi; Sagawa Hiroyuki

2013-01-01

319

GEANT4 validation in the calculation of absorbed dose in air due to gamma radiation emitted from the soil  

International Nuclear Information System (INIS)

Geant, is a monte Carlo code system conceived essentially for optimization of detectors in particle physics field. It found some usage in other high energy branches such as medical physics. GEANT4 toolkit system, written in C++ oriented object programation language, is the recent version of Geant code. This powerful simulation tool is believed to be a viable alternative to other codes based on Monte Carlo methods in the calculation of photon transport. We have developed a new optimized geometry to simulate the soil in a Monte Carlo calculation of absorbed dose in air due to gamma radiation from sources distributed in the ground. This geometry was successfully implemented in Geant4 System. The method relative to the implementation is described. Simulation tests were conducted to compare the results issued from different approches were the soil is modelled either by a simple shape like a cylinder or by our new geometry. This work seems to be important to validate Geant4 in the calculation of absorbed dose in air due to radioactive sources distributed in the soil and to confirm the usage of GEANT4 toolkit system in such field of nuclear physics

320

Particle size distribution measurement of indoor air aerosol at dwellings in a high background radiation area in Orissa, India  

International Nuclear Information System (INIS)

An estimation of activity size distribution of indoor air aerosol at dwellings in a high background radiation area (HBRA) in India was attempted with a commercially available portable particle size counter designed for not the activity but normal size distribution. The measurement was intensively implemented at 25 dwellings of 6 settlements around a coastal area of Orissa, India (19.4 °N, 85.0 °E) in daytime for the period of 21 to 26 Feb. 2010. Most of the houses were built of brick and cement, and some were mud houses. The number concentrations of aerosol particles in ranges of 0.3, 0.5, 1.0, 3.0 and 5.0 ?m diameters were measured every 1-2 min for about 1 h at each dwelling with a handy laser particle counter Model 3886 (KANOMAX, Osaka, Japan) combined a hand-made dilution system with ca. 300-fold volume of aerosol-free air. Radon-222 concentration was simultaneously measured every 10 mm with an AlphaGUARD (Saphymo GmhH, Germany) at all the measured houses, and those of short-lived radon decay products were with a LCD-BWLM-PLUS (Tracerlab GmbH, Germany) every 15 min at a part of the houses. In all the measurement, 222Rn concentration less than 30 Bq m-3 was measured, and several Bq m-3 of EECs were recorded

321

On the role of ventilation and air clean-up in the radiation safety ensurance for NPPs with WWER-1000  

International Nuclear Information System (INIS)

The main radiation hygiene principles are considered for ventilation of NPPs with WWER-1000 with airtight shell as well as the design solutions for the ventilation and air clean-up systems of the reactor premises. On the basis of the major gas and aerosol radiation release sources assessment and experience of Novo Voronezh NPP 5-th unit operation the efficiency of the ventilation and air clean-up systems design has been demonstrated from the viewpoint of the personnel safety and impact on the environment

322

Incorporating principal component analysis into air quality model evaluation  

Science.gov (United States)

The efficacy of standard air quality model evaluation techniques is becoming compromised as the simulation periods continue to lengthen in response to ever increasing computing capacity. Accordingly, the purpose of this paper is to demonstrate a statistical approach called Principal Component Analysis (PCA) with the intent of motivating its use by the evaluation community. One of the main objectives of PCA is to identify, through data reduction, the recurring and independent modes of variations (or signals) within a very large dataset, thereby summarizing the essential information of that dataset so that meaningful and descriptive conclusions can be made. In this demonstration, PCA is applied to a simple evaluation metric - the model bias associated with EPA's Community Multi-scale Air Quality (CMAQ) model when compared to weekly observations of sulfate (SO42-) and ammonium (NH4+) ambient air concentrations measured by the Clean Air Status and Trends Network (CASTNet). The advantages of using this technique are demonstrated as it identifies strong and systematic patterns of CMAQ model bias across a myriad of spatial and temporal scales that are neither constrained to geopolitical boundaries nor monthly/seasonal time periods (a limitation of many current studies). The technique also identifies locations (station-grid cell pairs) that are used as indicators for a more thorough diagnostic evaluation thereby hastening and facilitating understanding of the probable mechanisms responsible for the unique behavior among bias regimes. A sampling of results indicates that biases are still prevalent in both SO42- and NH4+ simulations that can be attributed to either: 1) cloud processes in the meteorological model utilized by CMAQ, which are found to overestimated convective clouds and precipitation, while underestimating larger-scale resolved clouds that are less likely to precipitate, and 2) biases associated with Midwest NH3 emissions which may be partially ameliorated using the bi-directional NH3 exchange option in CMAQ.

Eder, Brian; Bash, Jesse; Foley, Kristen; Pleim, Jon

2014-01-01

323

Development of a forecast model for global air traffic emissions  

Energy Technology Data Exchange (ETDEWEB)

The thesis describes the methodology and results of a simulation model that quantifies fuel consumption and emissions of civil air traffic. Besides covering historical emissions, the model aims at forecasting emissions in the medium-term future. For this purpose, simulation models of aircraft and engine types are used in combination with a database of global flight movements and assumptions about traffic growth, fleet rollover and operational aspects. Results from an application of the model include emissions of scheduled air traffic for the years 2000 to 2010 as well as forecasted emissions until the year 2030. In a baseline scenario of the forecast, input assumptions (e.g. traffic growth rates) are in line with predictions by the aircraft industry. Considering the effects of advanced technologies of the short-term and medium-term future, the forecast focusses on fuel consumption and emissions of nitric oxides. Calculations for historical air traffic additionally cover emissions of carbon monoxide, unburned hydrocarbons and soot. Results are validated against reference data including studies by the International Civil Aviation Organization (ICAO) and simulation results from international research projects. (orig.)

Schaefer, Martin

2012-07-01

324

Development of a hydrodynamic model for air-lift reactors  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a 1D hydrodynamic model has been developed for gas hold-up and liquid circulation velocity prediction in air-lift reactors. The model is based on momentum balance equations and has been adjusted to experimental data collected on a pilot plant reactor equipped with two types of gas distributors and using water and water/butanol as the liquid phase. Different techniques of signal analysis have also been applied to pressure fluctuations in order to extract information about flow regimes and regime transitions. A good knowledge of the flow pattern is essential to establish adequate correlations for the hydrodynamic model.

E. Carvalho

2000-12-01

325

Principal Component-Based Radiative Transfer Model (PCRTM) for Hyperspectral Sensors. Part I; Theoretical Concept  

Science.gov (United States)

Modern infrared satellite sensors such as Atmospheric Infrared Sounder (AIRS), Cosmic Ray Isotope Spectrometer (CrIS), Thermal Emission Spectrometer (TES), Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) and Infrared Atmospheric Sounding Interferometer (IASI) are capable of providing high spatial and spectral resolution infrared spectra. To fully exploit the vast amount of spectral information from these instruments, super fast radiative transfer models are needed. This paper presents a novel radiative transfer model based on principal component analysis. Instead of predicting channel radiance or transmittance spectra directly, the Principal Component-based Radiative Transfer Model (PCRTM) predicts the Principal Component (PC) scores of these quantities. This prediction ability leads to significant savings in computational time. The parameterization of the PCRTM model is derived from properties of PC scores and instrument line shape functions. The PCRTM is very accurate and flexible. Due to its high speed and compressed spectral information format, it has great potential for super fast one-dimensional physical retrievals and for Numerical Weather Prediction (NWP) large volume radiance data assimilation applications. The model has been successfully developed for the National Polar-orbiting Operational Environmental Satellite System Airborne Sounder Testbed - Interferometer (NAST-I) and AIRS instruments. The PCRTM model performs monochromatic radiative transfer calculations and is able to include multiple scattering calculations to account for clouds and aerosols.

Liu, Xu; Smith, William L.; Zhou, Daniel K.; Larar, Allen

2005-01-01

326

CFD model of air movement in ventilated facade: comparison between natural and forced air flow  

Energy Technology Data Exchange (ETDEWEB)

This study describes computational fluid dynamics (CFD) modeling of ventilated facade. Ventilated facades are normal facade but it has an extra channel between the concrete wall and the (double skin) facade. Several studies found in the literature are carried out with CFD simulations about the behavior of the thermodynamic phenomena of the double skin facades systems. These studies conclude that the presence of the air gap in the ventilated facade affects the temperature in the building skin, causing a cooling effect, at least in low-rise buildings. One of the most important factors affecting the thermal effects of ventilated facades is the wind velocity. In this contribution, a CFD analysis applied on two different velocity assumptions for air movement in the air gap of a ventilated facade is presented. A comparison is proposed considering natural wind induced velocity with forced fan induced velocity in the gap. Finally, comparing temperatures in the building skin, the differences between both solutions are described determining that, related to the considered boundary conditions, there is a maximum height in which the thermal effect of the induced flow is significantly observed.

Mora Perez, Miguel; Lopez Patino, Gonzalo; Lopez Jimenez, P. Amparo [Hydraulic and Environmental Engineering Department, Universitat Politècnica de Valencia (Spain)

2013-07-01

327

Radiation Belt Electron Dynamics: Modeling Atmospheric Losses  

Science.gov (United States)

The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

Selesnick, R. S.

2003-01-01

328

Radiation carbonization of cellulose, wood and lignin in the presence of air  

International Nuclear Information System (INIS)

The process of radiaton carbonization of wood and its separate components (cellulose and lignin) under the effect of ?-radiation is studied. In the process of cellulose and wood meal irradiation a decrease in hydrogen content with the growth of irradiation dose is observed. Simultaneously with hydrogen loss the dose of ? 100 kGy an increase in carbon content and a decrease in oxygen content are observed. In wood meal carbon content decreases, oxygen content increases. In lignin the observed changes in the element composition do not exceed experimental error. The results obtained are considered from the viewpoint of dehydration of radicals, formed in the process of irradiation, as well as their oxidation by the air oxygen

329

Radiation protection at the RA reactor, 1987 - Part IIb: Environmental radioactivity control, Air radioactivity control  

International Nuclear Information System (INIS)

During the period from November 1985 - November 1988, within the radioactivity control on the Vinca Institute site air contamination radioactive aerosol contents was measured. Control was done on 4 measuring stations, two in the Institute and two locations in the direction of wind i.e. Belgrade, 2 km and 7 km away from the Institute respectively. This position of the measuring locations enables control of radiation safety of the Institute, as well as environment of Belgrade taking into account the existence of the reactor and other possible contaminants in the Institute. It is mentioned that the state of the measuring instrumentation is unchanged compared to the previous years and does not provide the possibility of proper program for environmental radioactivity control

330

Application of air traffic control competence reference models as a mean of air navigation services provider’s charge optimization  

OpenAIRE

 The issue of application of Air Traffic Control (ATC) competence reference models as a mean of air navigation services provider’s charge optimization is described in the article, and this issue is interpretated as an optimization task. The data relating to the significant growth of aviation traffic, especially using the airspace of Ukraine, given by authors, and the statement of fact that Air Traffic Management (ATM) system’s technical component reliability increasement takes pla...

????????, ?. ?. ????????????? ???????????? ???????????; ????????, ?. ?. ???????? ???????????? ?????????????? ??????????? ???? ????????; ????????, ?. ?. ???????? ???????????? ?????????????? ??????????? ???? ????????

2010-01-01

331

Modeling shortwave radiative fluxes from satellites  

Science.gov (United States)

During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, satellite based estimates differ from each other and from those provided by numerical models. Major issues are related to quality of satellite observations, such as the frequent changes in satellite observing systems, degradation of sensors, restricted spectral intervals and viewing geometry of sensors, and changes in the quality of atmospheric inputs that drive the inference schemes. To reduce differences among the satellite based estimates requires, among others, updates to inference schemes so that most recent auxiliary information can be fully utilized. This paper reports on improvements introduced to a methodology developed at the University of Maryland to estimate shortwave (SW) radiative fluxes within the atmosphere system from satellite observations, the implementation of the approach with newly available auxiliary information, evaluation of the downwelling SW flux against ground observations, and comparison with independent satellite methods and numerical models. Specifically, introduced are: new Narrow to Broadband (N/B) transformations and new Angular Distribution Models (ADM) for clear and cloudy sky that incorporate most recent land use classifications; improved aerosol treatment; separation of clouds by phase; improved sun-earth geometry; and implementation at 0.5° spatial resolution at 3-hourly intervals integrated to daily and monthly time scales. When compared to an earlier version of the model as implemented at 2.5° at global scale and against observations from the globally distributed Baseline Surface Radiation Network (BSRN) stations for a period of six years (at monthly time scale), the bias was reduced from 8.6 (4.6%) to -0.5 (0.3%) W/m2, the standard deviation from 16.6 (8.9%) to 14.5 (7.8%) W/m2while the correlation remained high at 0.98 in both cases. Evaluation was also done over oceanic sites as available from the Pilot Research Moored Array in the Tropical Atlantic (PIRATA) moorings and from the Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) moorings in the tropical Pacific Ocean. Overall, results over oceans were not as good as over land for all the satellite retrievals compared in this study.

Ma, Y.; Pinker, R. T.

2012-12-01

332

Models for gaseous radiative heat transfer applied to oxy-fuel conditions in boilers  

Energy Technology Data Exchange (ETDEWEB)

Models of gas radiation properties have been evaluated for conditions relevant to oxy-fired boilers, characterized by larger pressure path-lengths and possibly different ratios of H{sub 2}O/CO{sub 2} compared to air-fired boilers. Statistical narrow band (SNB) models serve as reference. The other radiation models tested are the weighted-sum-of-grey-gases model, the spectral line-based weighted-sum-of-grey-gases model and two grey-gas approximations. The range of validity of the existing coefficients of the weighted-sum-of-grey-gases model is limited, and new coefficients have therefore been determined to cover the conditions of interest. Several assumed test cases, involving both uniform and non-uniform paths, have been studied to evaluate the accuracy of the models. Comparisons with experimental data are also included. The results show that a grey approximation can give accurate wall fluxes, but at the expense of errors in the radiative source term. The weighted-sum-of-grey-gases model with the new coefficients yields predictions within 20% of those of the reference model in most cases, while the spectral line-based weighted-sum-of-grey-gases model usually gives results within 10%. There are, however, discrepancies between the SNB models at high temperatures. The weighted-sum-of-grey-gases model with its low computational cost is recommended for computationally demanding applications where predictions of both wall fluxes and the radiative source term are important.

Johansson, R.; Andersson, K.; Leckner, B.; Thunman, H. [Chalmers University, Gothenburg (Sweden). Environmental & Energy Department

2010-01-15

333

Multipass air solar collectors  

Science.gov (United States)

Instantaneous thermal efficiencies are calculated for flat-plate solar collectors of various configurations which use air exposed to solar radiation or the solar absorber one or many times as the heat transport medium. The efficiencies of 18 potential models are obtained from numerical calculations of air flow and thermal loss distribution in the collector channels, incident solar radiation, solar radiation absorption, and the energy balance and air temperature increase following each pass through the collector. Plots of the instantaneous thermal efficiency as a function of inlet air temperature under standard operating conditions reveal that, if nonselective materials are used for the collector, models utilizing one or two covers with air flow only behind the solar absorber are most suitable, with only a few models with one cover and one selective surface having higher performance than the most efficient two-cover model with nonselective materials. For relatively high air inlet temperatures, a model with two covers and one selective surface having air flow only behind the absorber is also found to be superior. In the case of models with two selective covers, highest performance was obtained for models with parallel air flow in front of and behind the absorber, and flow only behind the absorber. It is noted that the use of two selective surfaces is, however, not justified at low inlet temperatures.

Granier, P.; Daguenet, M.

1981-06-01

334

Seine estuary modelling and AirSWOT measurements validation  

Science.gov (United States)

In the context of global climate change, knowing water fluxes and storage, from the global scale to the local scale, is a crucial issue. The future satellite SWOT (Surface Water and Ocean Topography) mission, dedicated to the surface water observation, is proposed to meet this challenge. SWOT main payload will be a Ka-band Radar Interferometer (KaRIn). To validate this new kind of measurements, preparatory airborne campaigns (called AirSWOT) are currently being designed. AirSWOT will carry an interferometer similar to Karin: Kaspar-Ka-band SWOT Phenomenology Airborne Radar. Some campaigns are planned in France in 2014. During these campaigns, the plane will fly over the Seine River basin, especially to observe its estuary, the upstream river main channel (to quantify river-aquifer exchange) and some wetlands. The present work objective is to validate the ability of AirSWOT and SWOT, using a Seine estuary hydrodynamic modelling. In this context, field measurements will be collected by different teams such as GIP (Public Interest Group) Seine Aval, the GPMR (Rouen Seaport), SHOM (Hydrographic and Oceanographic Service of the Navy), the IFREMER (French Research Institute for Sea Exploitation), Mercator-Ocean, LEGOS (Laboratory of Space Study in Geophysics and Oceanography), ADES (Data Access Groundwater) ... . These datasets will be used first to validate locally AirSWOT measurements, and then to improve a hydrodynamic simulations (using tidal boundary conditions, river and groundwater inflows ...) for AirSWOT data 2D validation. This modelling will also be used to estimate the benefit of the future SWOT mission for mid-latitude river hydrology. To do this modelling,the TUGOm barotropic model (Toulouse Unstructured Grid Ocean model 2D) is used. Preliminary simulations have been performed by first modelling and then combining to different regions: first the Seine River and its estuarine area and secondly the English Channel. These two simulations h are currently being improved, by testing different roughness coefficients, adding tributary inflows. Groundwater contributions will also be introduced (digital TUGOm development in progress) . The model outputs will be validated using data from the GPMR tide gauge data and measurements from the Topex/Poseidon and Jason-1/-2 altimeters for year 2007.

Chevalier, Laetitia; Lyard, Florent; Laignel, Benoit

2013-04-01

335

Development of an air quality model for BCL Limited  

OpenAIRE

In order to understand the impact from a point source of pollution a comprehensive air quality monitoring programme must be in place. Measurement stations are at fixed locations and can only measure the relevant concentration if the wind is blowing in a particular direction. With changing wind direction, a measurement station needs to be coupled with a dispersion model to predict the impact from a point source, such as the BCL Limited smelter. The smelter produces 55 500 tonnes per annum of n...

Tshukudu, Tiroyaone

2005-01-01

336

An analytical air pollution model: development and evaluation  

Energy Technology Data Exchange (ETDEWEB)

An analytical air quality dispersion model based on a discretization of the planetary boundary layer in N sublayers is presented. In each sublayer the diffusion-advection equation is solved by the Laplace transform techniques, considering an average value for the vertical exchange coefficient and the wind speed. This approach allows us to conjugate the advantages of the dispersion models based on analytical solutions and the more realistic wind and eddy diffusivity profiles related to a progress in the understanding of the planetary boundary layer structure. The model`s performances have been evaluated using the well-known Copenhagen dataset as well as the analytical model evaluating ground level concentrations from elevated sources (Tirabassi and Rizza, 1994). Then, the application of the statistical evaluation procedure (Hanna, 1989) over the outcoming results has shown that the proposed analytical dispersion model produces a good fitting of the observational data. (orig.) 13 refs.

Vilhena de, M.T.; Moreira, D.M. [Univ. Federale de Rio Grande do Sul, Porto Alegre (Brazil); Rizza, U.; Degrazia, G.A.; Mangia, C.; Tirabassi, T.

1998-08-01

337

Air  

International Nuclear Information System (INIS)

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

338

ANN-based modelling and estimation of daily global solar radiation data: A case study  

International Nuclear Information System (INIS)

In this paper, an artificial neural network (ANN) models for estimating and modelling of daily global solar radiation have been developed. The data used in this work are the global irradiation HG, diffuse irradiation HD, air temperature T and relative humidity Hu. These data are available from 1998 to 2002 at the National Renewable Energy Laboratory (NREL) website. We have developed six ANN-models by using different combination as inputs: the air temperature, relative humidity, sunshine duration and the day of year. For each model, the output is the daily global solar radiation. Firstly, a set of 4 x 365 points (4 years) has been used for training each networks, while a set of 365 points (1 year) has been used for testing and validating the ANN-models. It was found that the model using sunshine duration and air temperature as inputs, gives good accurate results since the correlation coefficient is 97.65%. A comparative study between developed ANN-models and conventional regression models is presented in this study.

339

ANN-based modelling and estimation of daily global solar radiation data: A case study  

Energy Technology Data Exchange (ETDEWEB)

In this paper, an artificial neural network (ANN) models for estimating and modelling of daily global solar radiation have been developed. The data used in this work are the global irradiation H{sub G}, diffuse irradiation H{sub D}, air temperature T and relative humidity H{sub u}. These data are available from 1998 to 2002 at the National Renewable Energy Laboratory (NREL) website. We have developed six ANN-models by using different combination as inputs: the air temperature, relative humidity, sunshine duration and the day of year. For each model, the output is the daily global solar radiation. Firstly, a set of 4 x 365 points (4 years) has been used for training each networks, while a set of 365 points (1 year) has been used for testing and validating the ANN-models. It was found that the model using sunshine duration and air temperature as inputs, gives good accurate results since the correlation coefficient is 97.65%. A comparative study between developed ANN-models and conventional regression models is presented in this study. (author)

Benghanem, M.; Alamri, S.N. [Department of Physics, Faculty of Sciences, Taibah University, P.O. Box 344, Medina (Saudi Arabia); Mellit, A. [Department of LMD/Electronics, Faculty of Sciences Engineering, LAMEL, Jijel University, Ouled-aissa, P.O. Box 98, Jijel 18000 (Algeria)

2009-07-15

340

Improving ammonia emissions in air quality modelling for France  

Science.gov (United States)

We have implemented a new module to improve the representation of ammonia emissions from agricultural activities in France with the objective to evaluate the impact of such emissions on the formation of particulate matter modelled with the air quality model CHIMERE. A novel method has been set up for the part of ammonia emissions originating from mineral fertilizer spreading. They are calculated using the one dimensional 1D mechanistic model “VOLT'AIR” which has been coupled with data on agricultural practices, meteorology and soil properties obtained at high spatial resolution (cantonal level). These emissions display high spatiotemporal variations depending on soil pH, rates and dates of fertilization and meteorological variables, especially soil temperature. The emissions from other agricultural sources (animal housing, manure storage and organic manure spreading) are calculated using the national spatialised inventory (INS) recently developed in France. The comparison of the total ammonia emissions estimated with the new approach VOLT'AIR_INS with the standard emissions provided by EMEP (European Monitoring and Evaluation Programme) used currently in the CHIMERE model shows significant differences in the spatiotemporal distributions. The implementation of new ammonia emissions in the CHIMERE model has a limited impact on ammonium nitrate aerosol concentrations which only increase at most by 10% on the average for the considered spring period but this impact can be more significant for specific pollution episodes. The comparison of modelled PM10 (particulate matter with aerodynamic diameter smaller than 10 ?m) and ammonium nitrate aerosol with observations shows that the use of the new ammonia emission method slightly improves the spatiotemporal correlation in certain regions and reduces the negative bias on average by 1 ?g m-3. The formation of ammonium nitrate aerosol depends not only on ammonia concentrations but also on nitric acid availability, which is often a limiting factor in rural regions in France, and on meteorological conditions. The presented approach of ammonia emission calculation seems suitable for use in chemistry-transport models.

Hamaoui-Laguel, Lynda; Meleux, Frédérik; Beekmann, Matthias; Bessagnet, Bertrand; Génermont, Sophie; Cellier, Pierre; Létinois, Laurent

2014-08-01

341

Theoretical model of Saturn's kilometric radiation spectrum  

International Nuclear Information System (INIS)

A theoretical model is developed here in order to determine an envelope for the average spectrum of the Saturnian kilometric radiation (SKR). The microscopic generation mechanism is supposed to be the so-called synchrotron (or cyclotron) maser instability. As in recent works on the terrestrial kilometric radiation, the effect of the magnetic field inhomogeneity on the generation process must be taken into account. Then, assuming that the emission is nonlinearly saturated by trapping, the calculation allows the authors to put an upper limit on the SKR spectral intensity very simply: the maximum level of the wave electric field within the source region is indeed linked to a few macroscopic plasma parameters, which can be derived from the observations (the structure of the magnetospheric magnetic field, the cold plasma density, and the characteristic energy of the hot emitting electrons). They have used a dipolar magnetic field model, while the plasma distribution results from the superposition of two components, an ionospheric population and a plasma disc, whose scale heights have been roughly determined from Voyager measurements. The energetic electrons responsible for the emission are supposed to precipitate along the high-latitude magnetic field lines where SKR emission is known to take place. The width of the source region can be self-consistently estimated from the model. A very good agreement is obtained between the theoretical spectrum and the observational radiotical spectrum and the observational radio data. The calculated spectral intensities exceed the most intense observed intensities by up to 1 order of magnitude, suggesting that the SKR emission is only marginally saturated by nonlinear processes

342

Space-Time Fusion Under Error in Computer Model Output: An Application to Modeling Air Quality  

Science.gov (United States)

In the last two decades a considerable amount of research effort has been devoted to modeling air quality with public health objectives. These objectives include regulatory activities such as setting standards along with assessing the relationship between exposure to air pollutan...

343

Flavour Dependent Gauged Radiative Neutrino Mass Model  

CERN Document Server

We propose a one-loop induced radiative neutrino mass model with anomaly free flavour dependent gauge symmetry: $\\mu$ minus $\\tau$ symmetry $U(1)_{\\mu-\\tau}$. A neutrino mass matrix satisfying current experimental data can be obtained by introducing a weak isospin singlet scalar boson that breaks $U(1)_{\\mu-\\tau}$ symmetry, an inert doublet scalar field, and three right-handed neutrinos in addition to the fields in the standard model. We find that a characteristic structure appears in the neutrino mass matrix: two-zero texture form which predicts three non-zero neutrino masses and three non-zero CP-phases which can be determined five well measured experimental inputs of two squared mass differences and three mixing angles. Furthermore, it is clarified that only the inverted mass hierarchy is allowed in our model. In a favored parameter set from the neutrino sector, the discrepancy in the muon anomalous magnetic moment between the experimental data and the the standard model prediction can be explained by the ...

Baek, Seungwon; Yagyu, Kei

2015-01-01

344

The air quality forecast in Beijing with Community Multi-scale Air Quality Modeling (CMAQ) System: model evaluation and improvement  

Science.gov (United States)

The MM5-SMOKE-CMAQ model system, which is developed by the United States Environmental Protection Agency(U.S. EPA) as the Models-3 system, has been used for the daily air quality forecast in the Beijing Municipal Environmental Monitoring Center(Beijing MEMC), as a part of the Ensemble Air Quality Forecast System for Beijing(EMS-Beijing) since the Olympic Games year 2008. In this study, we collect the daily forecast results of the CMAQ model in the whole year 2010 for the model evaluation. The results show that the model play a good model performance in most days but underestimate obviously in some air pollution episode. A typical air pollution episode from 11st - 20th January 2010 was chosen, which the air pollution index(API) of particulate matter (PM10) observed by Beijing MEMC reaches to 180 while the prediction of PM10-API is about 100. Taking in account all stations in Beijing, including urban and suburban stations, three numerical methods are used for model improvement: firstly, enhance the inner domain with 4km grids, the coverage from only Beijing to the area including its surrounding cities; secondly, update the Beijing stationary area emission inventory, from statistical county-level to village-town level, that would provide more detail spatial informance for area emissions; thirdly, add some industrial points emission in Beijing's surrounding cities, the latter two are both the improvement of emission. As the result, the peak of the nine national standard stations averaged PM10-API, which is simulated by CMAQ as daily hindcast PM10-API, reach to 160 and much near to the observation. The new results show better model performance, which the correlation coefficent is 0.93 in national standard stations average and 0.84 in all stations, the relative error is 15.7% in national standard stations averaged and 27% in all stations. The time series of 9 national standard in Beijing urban The scatter diagram of all stations in Beijing, the red is the forecast and the blue is new result.

Wu, Q.

2013-12-01

345

Ultraviolet radiation therapy and UVR dose models.  

Science.gov (United States)

Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed. PMID:25563284

Grimes, David Robert

2015-01-01

346

EMMA model: an advanced operational mesoscale air quality model for urban and regional environments  

International Nuclear Information System (INIS)

Mesoscale air quality models are an important tool to forecast and analyse the air quality in regional and urban areas. In recent years an increased interest has been shown by decision makers in these types of software tools. The complexity of such a model has grown exponentially with the increase of computer power. Nowadays, medium workstations can run operational versions of these modelling systems successfully. Presents a complex mesoscale air quality model which has been installed in the Environmental Office of the Madrid community (Spain) in order to forecast accurately the ozone, nitrogen dioxide and sulphur dioxide air concentrations in a 3D domain centred on Madrid city. Describes the challenging scientific matters to be solved in order to develop an operational version of the atmospheric mesoscale numerical pollution model for urban and regional areas (ANA). Some encouraging results have been achieved in the attempts to improve the accuracy of the predictions made by the version already installed. (Author)

347

X-ray radiation from the volume discharge in atmospheric-pressure air  

Science.gov (United States)

X-ray radiation from the volume discharge in atmospheric-pressure air is studied under the conditions when the voltage pulse rise time varies from 0.5 to 100 ns and the open-circuit voltage amplitude of the generator varies from 20 to 750 kV. It is shown that a volume discharge from a needle-like cathode forms at a relatively wide voltage pulse (to ?60 ns in this work). The volume character of the discharge is due to preionization by fast electrons, which arise when the electric field concentrates at the cathode and in the discharge gap. As the voltage pulse rise time grows, X-ray radiation comes largely from the discharge gap in accordance with previous experiments. Propagation of fast avalanche electrons in nitrogen subjected to a nonuniform unsteady electric field is simulated. It is demonstrated that the amount of hard X-ray photons grows not only with increasing voltage amplitude but also with shortening pulse rise time.

Bratchikov, V. B.; Gagarinov, K. A.; Kostyrya, I. D.; Tarasenko, V. F.; Tkachev, A. N.; Yakovlenko, S. I.

2007-07-01

348

Estimation of Pan Evaporation Using Mean Air Temperature and Radiation for Monsoon Season in Junagadh Region  

Directory of Open Access Journals (Sweden)

Full Text Available The abstract should summarize the content of the paper. Try to keep the abstract below 200 words. Do not make references nor display equations in the abstract. The journal will be printed from the same-sized copy prepared by you. Your manuscript should be printed on A4 paper (21.0 cm x 29.7 cm. It is imperative that the margins The significance of major meteorological factors, that influence the evaporation were evaluated at daily time-scale for monsoon season using the data from Junagadh station, Gujarat (India. The computed values were compared. The solar radiation and mean air temperature were found to be the significant factors influencing pan evaporation (Ep. The negative correlation was found between relative humidity and (Ep, while wind speed, vapour pressure deficit and bright sunshine hours were found least correlated and no longer remained controlling factors influencing (Ep. The objective of the present study is to compare and evaluate the performance of six different methods based on temperature and radiation to select the most appropriate equations for estimating (Ep. The three quantitative standard statistical performance evaluation measures, coefficient of determination (R2 root mean square of errors-observations standard deviation ratio (RSR and Nash-Sutcliffe efficiency coefficient (E are employed as performance criteria. The results show that the Jensen equation yielded the most reliable results in estimation of (Ep and it can be recommended for estimating (Ep for monsoon season in the study region.

Manoj J. Gundalia

2013-11-01

349

A neural network based intelligent predictive sensor for cloudiness, solar radiation and air temperature  

OpenAIRE

Accurate measurements of global solar radiation and atmospheric temperature, as well as the availability of the predictions of their evolution over time, are important for different areas of applications, such as agriculture, renewable energy and energy management, or thermal comfort in buildings. For this reason, an intelligent, light-weight and portable sensor was developed, using artificial neural network models as the time-series predictor mechanisms. These have been identified with the a...

Ferreira, Pedro M.; Ruano, Anto?nio E.; Gomes, Joa?o M.; Martins, Igor A. C.

2012-01-01

350

Microphysical and Radiative Modelling of the Venus Condensational Middle Cloud  

Science.gov (United States)

I am using the CU / NASA Ames CARMA (Community Aerosol and Radiation Model Atmosphere) code to model the microphysical and radiative properties of the Venus middle cloud deck. The current (1-D) model reproduces the globally averaged Venus atmosphere -- as compared with Pioneer Venus LCPS observations -- in particle concentration and optical depth. The current model now conserves particle number, as well as particle mass in the simulation of nucleation, growth and evaporation of two species (sulfuric acid and water). We have coupled a radiation code to the microphysics to investigate the radiative forcings in the cloud. This work is funded through grant NCC2-1052.

McGouldrick, K.; Toon, O. B.

2003-05-01

351

Improved estimate of global dust radiative forcing using a coupled chemical transport-radiative transfer model  

OpenAIRE

Atmospheric mineral dust particles exert significant direct radiative forcings and are critical drivers of climate change. Here, we use the GEOS-Chem global three-dimensional chemical transport model (3-D CTM) coupled online with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rates based on different dust vertical profiles. The coupled calculations using a realistic dust vertical profile simulated by GEOS-Chem minimize the phys...

Zhang, L.; Li, Q. B.; Gu, Y.; Liou, K. N.; Meland, B.

2013-01-01

352

Modeling of external radiation from the transport of radionuclides across a canyon  

International Nuclear Information System (INIS)

The Los Alamos Meson Physics Facility (LAMPF) is an 800-million electron volt, l mA intensity linear proton accelerator used for studying subatomic particles at relativistic velocities. Routine operation of the accelerator results in the formation of short-lived air activation products, primarily in the beam stop section of LAMPF. This study presents the results of monitoring and modeling external radiation levels from LAMPF emissions at three locations during 1984. Measured radiation exposures are presented for all three locations during a 49-day period. Hourly radiation levels are calculated for all sites and compared with the prevalent wind patterns during the study period. Predicted daily levels are compared with measured values at all of the sites. Accuracy of the model is compared for day and night conditions. Annual model predictions are also compared with TLD measurements

353

Infrared Radiography: Modeling X-ray Imaging without Harmful Radiation  

Science.gov (United States)

Planar x-ray imaging is a ubiquitous diagnostic tool and is routinely performed to diagnose conditions as varied as bone fractures and pneumonia. The underlying principle is that the varying attenuation coefficients of air, water, tissue, bone, or metal implants within the body result in non-uniform transmission of x-ray radiation. Through the…

Zietz, Otto; Mylott, Elliot; Widenhorn, Ralf

2015-01-01

354

Stochastic modeling of p53-regulated apoptosis upon radiation damage  

CERN Document Server

We develop and study the evolution of a model of radiation induced apoptosis in cells using stochastic simulations, and identified key protein targets for effective mitigation of radiation damage. We identified several key proteins associated with cellular apoptosis using an extensive literature survey. In particular, we focus on the p53 transcription dependent and p53 transcription independent pathways for mitochondrial apoptosis. Our model reproduces known p53 oscillations following radiation damage. The key, experimentally testable hypotheses that we generate are - inhibition of PUMA is an effective strategy for mitigation of radiation damage if the treatment is administered immediately, at later stages following radiation damage, inhibition of tBid is more effective.

Bhatt, Divesh; Bahar, Ivet

2011-01-01

355

A diffusion model for antiprotons and protons of cosmic radiation  

International Nuclear Information System (INIS)

One target was to explain antiprotons in cosmic radiation. These particles are of special interest because they cannot or only partially be described by the classic propagation models of cosmic radiation. On the other hand, however, the nuclei flows as calculated by the ''leaky-box'' model show good correlation with the measured follow of the nuclei in cosmic radiation. The thesis also deals with the interpretation of the radial decrease of the proton flow of cosmic radiation in the galaxies (gradient) and the way in which this is connected to antiprotons. The leaky-box model assumes a monogeneous distribution of cosmic radiation in ghe galaxies, so that this gradient is a contradiction to the basic assumption of the leaky-box model. According to relevant observation results in the area of cosmic radiation a diffusion model is proposed which is locally independent and still simple enough to produce a random gradient needed for observation. (orig.)

356

40 CFR Appendix W to Part 51 - Guideline on Air Quality Models  

Science.gov (United States)

...EPA and others in air quality and meteorological modeling...3.0Recommended Air Quality Models 3.1Preferred...2National Weather Service Data 8.3.3Site...Summaries of Preferred Air Quality Models List of Tables...quality measurements, monitoring data normally...

2010-07-01

357

Numerical analysis of radiation effects in a metallic foam by means of the radiative conductivity model  

International Nuclear Information System (INIS)

The aim of this work is the evaluation of the radiation contribution to the steady-state heat transfer in metallic foams by means of the radiative conductivity model. Because of the complexity of the structure, reference is made to a simplified physical radiative model, where the elementary cell of the foams is treated as a cubic cell. The contribution of the radiation heat transfer is investigated on a local basis. The local radiative conductivity has been used to evaluate the influence of radiative heat transfer in a two dimensional conductive-convective-radiative problem involving a forced fluid flow within a heated channel filled with a metallic foam. The effect of the solid emissivity and the foam porosity is pointed out for different foams.

358

Methodology for modeling the microbial contamination of air filters.  

Science.gov (United States)

In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter. PMID:24523908

Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

2014-01-01

359

The NIMO Monte Carlo model for box-air-mass factor and radiance calculations  

International Nuclear Information System (INIS)

A new fully spherical multiple scattering Monte Carlo radiative transfer model named NIMO (NIWA Monte Carlo model) is presented. The ray tracing algorithm is described in detail along with the treatment of scattering and absorption, and the simulation of backward adjoint trajectories. The primary application of NIMO is the calculation of box-air-mass factors (box-AMFs), which are used to convert slant column densities (SCDs) of trace gases, derived from UV-visible multiple axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements, into vertical column densities (VCDs). Box-AMFs are also employed as weighting functions for optimal estimation retrievals of vertical trace gas profiles from SCDs. Monte Carlo models are well suited to AMF calculations at high solar zenith angles (SZA) and at low viewing elevation angles where multiple scattering is important. Additionally, the object-oriented structure of NIMO makes it easily extensible to new applications by plugging in objects for new absorbing or scattering species. Box-AMFs and radiances, calculated for various wavelengths, SZAs, viewing elevation and azimuth angles and aerosol scenarios, are compared with results from nine other models using a set of exercises from a recent radiative transfer model intercomparison. NIMO results for these simulations are well within the range of variability of the other models.

360

A mathematical model for radiation hydrodynamics  

Directory of Open Access Journals (Sweden)

Full Text Available We adopt here the idea of describing a radiation field by means of the radiation energy density E and the radiative flux vector F which must satisfy a set of evolution equations; in these equations an unknown tensorial function P(E,F appears that is determined by the methods of extended thermodynamics.

Sebastiano Pennisi

1990-11-01

361

A mathematical model for radiation hydrodynamics  

OpenAIRE

We adopt here the idea of describing a radiation field by means of the radiation energy density E and the radiative flux vector F which must satisfy a set of evolution equations; in these equations an unknown tensorial function P(E,F) appears that is determi...

Sebastiano Pennisi; Marco Sammartino

1990-01-01

362

Air pollutants and energy pathways; Extending models for abatement strategies  

International Nuclear Information System (INIS)

This study presents the development and applications of regional and local scale models for use in integrated assessment of air pollution effects in conjunction with large-scale models. A regional deposition model called DAIQUIRI (Deposition, AIr QUality and Integrated Regional Information) for integrated assessment purposes in Finland was constructed, and regional matrices for nitrogen oxides and ammonia were developed from the results of the regional air quality model of the FMI. DAIQUIRI produced similar estimates of deposition from Finnish sources as the original model, and long-term trends and the average level of deposition estimated with DAIQUIRI were found comparable with the monitored deposition levels and trends. For the mid-nineties situation, the regional nitrogen modeling resulted in 9 % to 19 % (depending on the region compared) larger estimates of areas with acidity critical load exceedances than when using European scale nitrogen deposition modeling. In this work, also a method for estimating the impacts of local NOx emissions on urban and sub-urban ozone levels was developed and tested. The study concentrated on representing the destruction of ozone by fresh NO emissions in urban areas for future use in integrated assessment modeling of ozone control strategies. Correlation coefficients between measured daytime ozone values in the study area were found to improve from 0.64 (correlation between urban and surrounding rural measurements) to 0. and surrounding rural measurements) to 0.85, on the average. The average correlation between daytime large-scale model estimates and urban site measurements was found to improve from 0.37 to 0.58. In the study, also integrated assessment model applications were carried out at European, national and local levels. The synergies between control strategies for CO2 and acidification and ozone formation in the case of the UN/FCCC Kyoto protocol and the air quality targets of the EU were assessed with the help of coupled models. With two alternative energy scenarios reflecting the Kyoto targets for CO2, reductions of sulfur and NOx emissions between 12 % and 22 % and 8 % to 12 %, respectively, were estimated by 2010 in the EU-15 with the present emission control legislation. Due to the lower activity levels generating less emissions and the cleaner energy forms used, 35-43 % cost savings in further technical emission controls required for achieving the EU air quality targets would be achieved with the scenarios studied. Case studies for Finland indicated that there has been a decrease of 60 % in the area at risk of acidification from 1990 to 1995, and that the declining trend is expected to continue due to the recent international emission reduction agreements within the UN/ECE and the EU. Implementation of the Kyoto protocol in Finland and in the whole of EU-15 (with the present emission legislation) could bring up to 8 % more reduction of ecosystems at risk of acidification in Finland by 2010 than the recent UN/ECE protocol. An uncertainty analysis of acidification integrated assessment modeling in Finland indicated that critical loads dominate the uncertainty. Estimates are becoming more robust, as the general level of deposition is decreasing. In Finland, further efforts to reduce the overall uncertainty should be mainly directed to more accurate description of critical thresholds. In areas affected by major nearby emission sources, also uncertainties in emissions and deposition are significant. The models and their applications presented in this study contributed to identifying the problem characteristics and have supported environmental policy development at international, national and regional levels. (orig.)

363

Gravitational Radiation from Ultra High Energy Cosmic Rays in Models with Large Extra Dimensions  

CERN Document Server

The effects of classical gravitational radiation in models with large extra dimensions are investigated for ultra high energy cosmic rays (CRs). The cross sections are implemented into a simulation package (SENECA) for high energy hadron induced CR air showers. We predict that gravitational radiation from quasi-elastic scattering could be observed at incident CR energies above $10^9$ GeV for a setting with more than two extra dimensions. It is further shown that this gravitational energy loss can alter the energy reconstruction for CR energies $E_{\\rm CR}\\ge 5\\cdot 10^9$ GeV.

Koch, B; Bleicher, M; Koch, Ben; Drescher, Hans-Joachim; Bleicher, Marcus

2006-01-01

364

New calculation method for thermodynamic properties of humid air in humid air turbine cycle – The general model and solutions for saturated humid air  

International Nuclear Information System (INIS)

The article proposes a new calculation method for thermodynamic properties (i.e. specific enthalpy, specific entropy and specific volume) of humid air in humid air turbine cycle. The research pressure range is from 0.1 MPa to 5 MPa. The fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. The new model proposes and verifies the relationship between total gas mixture pressure and gas component pressures. This provides a good explanation of the fundamental behaviors of gas components in gas mixture from a new perspective. Another discovery is that the water vapor component pressure of saturated humid air equals PS, always smaller than its partial pressure (f·PS) which was believed in the past researches. In the new model, “Local Gas Constant” describes the interaction between similar molecules. “Improvement Factor” is proposed for the first time by this article, and it quantitatively describes the magnitude of interaction between dissimilar molecules. They are combined to fully describe the real thermodynamic properties of humid air. The average error of Revised Dalton's Method is within 0.1% compared to experimentally-based data. - Highlights: • Our new model is suitable to calculate thermodynamic properties of humid air in HAT cycle. • Fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. • Local-Gas-Constant describes existing alone component and Improvement Factor describes interaction between different components. • The new model proposes and verifies the relationship between total gas mixture pressure and component pressures. • It solves saturated humid air thoroughly and deviates from experimental data less than 0.1%

365

Effect of surface radiation on the breakdown of steady natural convection flows in a square, air-filled cavity containing a centered inner body  

International Nuclear Information System (INIS)

The physical model considered in the present numerical work is a square air-filled cavity cooled from below and above, with a heated square body located at the cavity center. The aim is to establish the effects of radiation interchanges amongst surfaces on the transition from steady, symmetric flows about the cavity centerline to complex periodic flows. Owing to the low temperature differences involved (1 K ? ?T ? 5 K), the two-dimensional model is based on the Boussinesq approximation and constant thermophysical fluid properties at room temperature. The cavity walls are assumed gray and diffuse. The flow structure is investigated for various Rayleigh numbers, emissivities of the wall surfaces and sizes of the inner body. The results clearly establish the influence of surface radiation, both for steady and unsteady flows. For the geometry and thermal boundary conditions considered, the Rayleigh number for the transition to unsteady flows is considerably increased under the influence of radiation. This work underlines the difficulties in comparing experimental data and numerical solutions for gas-filled cavities partly subjected to wall heat flux boundary conditions. - Research highlights: ? Heat transfer in cavities cooled from below and above with an inner heated body. ? Effects of radiation on the transitions to unsteady flows are numerically studied. ? The surfaces are gray and diffuse and the temperature differences are from 1 K to 5 K. ? Critical Rayom 1 K to 5 K. ? Critical Rayleigh numbers are considerably increased by radiation. ? According to the thermal boundary conditions, combined analyses are required.

366

Comparison of the performance of net radiation calculation models  

DEFF Research Database (Denmark)

Daily values of net radiation are used in many applications of crop-growth modeling and agricultural water management. Measurements of net radiation are not part of the routine measurement program at many weather stations and are commonly estimated based on other meteorological parameters. Daily values of net radiation were calculated using three net outgoing long-wave radiation models and compared to measured values. Four meteorological datasets representing two climate regimes, a sub-humid, high-latitude environment and a semi-arid mid-latitude environment, were used to test the models. The long-wave radiation models included a physically based model, an empirical model from the literature, and a new empirical model. Both empirical models used only solar radiation as required for meteorological input. The long-wave radiation models were used with model calibration coefficients from the literature and with locally calibrated ones. A measured, average albedo value of 0.25 was used at the high-latitude sites. A fixed albedo value of 0.25 resulted in less bias and scatter at the mid-latitude sites compared to other albedo values. When used with model coefficients calibrated locally or developed for specific climate regimes, the predictions of the physically based model had slightly lower bias and scatter than the empirical models. When used with their original model coefficients, the physically based model had a higher bias than the measurement error of the net radiation instruments used. The performance of the empirical models was nearly identical at all sites. Since the empirical models were easier to use and simpler to calibrate than the physically based models, the results indicate that the empirical models can be used as a good substitute for the physically based ones when available meteorological input data is limited. Model predictions were found to have a higher bias and scatter when using summed calculated hourly time steps compared to using daily input data.

Kjærsgaard, Jeppe Hvelplund; Cuenca, R H

2009-01-01

367

Modeling and simulation of radiation from hypersonic flows with Monte Carlo methods  

Science.gov (United States)

During extreme-Mach number reentry into Earth's atmosphere, spacecraft experience hypersonic non-equilibrium flow conditions that dissociate molecules and ionize atoms. Such situations occur behind a shock wave leading to high temperatures, which have an adverse effect on the thermal protection system and radar communications. Since the electronic energy levels of gaseous species are strongly excited for high Mach number conditions, the radiative contribution to the total heat load can be significant. In addition, radiative heat source within the shock layer may affect the internal energy distribution of dissociated and weakly ionized gas species and the number density of ablative species released from the surface of vehicles. Due to the radiation total heat load to the heat shield surface of the vehicle may be altered beyond mission tolerances. Therefore, in the design process of spacecrafts the effect of radiation must be considered and radiation analyses coupled with flow solvers have to be implemented to improve the reliability during the vehicle design stage. To perform the first stage for radiation analyses coupled with gas-dynamics, efficient databasing schemes for emission and absorption coefficients were developed to model radiation from hypersonic, non-equilibrium flows. For bound-bound transitions, spectral information including the line-center wavelength and assembled parameters for efficient calculations of emission and absorption coefficients are stored for typical air plasma species. Since the flow is non-equilibrium, a rate equation approach including both collisional and radiatively induced transitions was used to calculate the electronic state populations, assuming quasi-steady-state (QSS). The Voigt line shape function was assumed for modeling the line broadening effect. The accuracy and efficiency of the databasing scheme was examined by comparing results of the databasing scheme with those of NEQAIR for the Stardust flowfield. An accuracy of approximately 1 % was achieved with an efficiency about three times faster than the NEQAIR code. To perform accurate and efficient analyses of chemically reacting flowfield - radiation interactions, the direct simulation Monte Carlo (DSMC) and the photon Monte Carlo (PMC) radiative transport methods are used to simulate flowfield - radiation coupling from transitional to peak heating freestream conditions. The non-catalytic and fully catalytic surface conditions were modeled and good agreement of the stagnation-point convective heating between DSMC and continuum fluid dynamics (CFD) calculation under the assumption of fully catalytic surface was achieved. Stagnation-point radiative heating, however, was found to be very different. To simulate three-dimensional radiative transport, the finite-volume based PMC (FV-PMC) method was employed. DSMC - FV-PMC simulations with the goal of understanding the effect of radiation on the flow structure for different degrees of hypersonic non-equilibrium are presented. It is found that except for the highest altitudes, the coupling of radiation influences the flowfield, leading to a decrease in both heavy particle translational and internal temperatures and a decrease in the convective heat flux to the vehicle body. The DSMC - FV-PMC coupled simulations are compared with the previous coupled simulations and correlations obtained using continuum flow modeling and one-dimensional radiative transport. The modeling of radiative transport is further complicated by radiative transitions occurring during the excitation process of the same radiating gas species. This interaction affects the distribution of electronic state populations and, in turn, the radiative transport. The radiative transition rate in the excitation/de-excitation processes and the radiative transport equation (RTE) must be coupled simultaneously to account for non-local effects. The QSS model is presented to predict the electronic state populations of radiating gas species taking into account non-local radiation. The definition of the escape factor which is depende

Sohn, Ilyoup

368

Application of receptor modeling to indoor air emissions from electroplating  

Energy Technology Data Exchange (ETDEWEB)

In work areas containing multiple sources of the same air pollutant, it is useful for control purposes to be able to separate out the contribution from each individual source. In this study, the chemical mass balance (CMB) receptor model was used to allocate the contributions from multiple sources to area concentration measurements in three electroplating shops. Shop 1 was a room with a single copper electroplating line; shop 2 was a large bay containing a chromium conversion coating line, a continuous chromium electroplating line, and several manual electroplating operations; shop 3 contained a piston chrome plating line, a decorative chrome plating line, and manual and barrel zinc coating lines. The receptor modeling approach uses the elemental composition of one or more source categories to determine what fraction of an area sample is contributed by each source. In most cases the CMB model predicted over 90% of the measured concentrations. The allocation procedure explained 100% of the copper measured at three locations in shop 1, with contributions of 95 to 98% from the plating line and the rest from air outside the room. For shop 2, a two-source model explained 100% of the chromium measured at five sampling locations. For shop 3, the percent contributions of chromium from the piston plating line and the decorative plating line were consistent with distance from each of the sources.

Wadden, R.A.; Liao, S.L.; Scheff, P.A.; Franke, J.E.; Conroy, L.M. [Univ. of Illinois, Chicago, IL (United States). School of Public Health

1998-12-01

369

Virtual models of indoor-air-quality sensors  

Energy Technology Data Exchange (ETDEWEB)

A data-driven approach for modeling indoor-air-quality (IAQ) sensors used in heating, ventilation, and air conditioning (HVAC) systems is presented. The IAQ sensors considered in the paper measure three basic parameters, temperature, CO{sub 2}, and relative humidity. Three models predicting values of IAQ parameters are built with various data mining algorithms. Four data mining algorithms have been tested on the HVAC data set collected at an office-type facility. The computational results produced by models built with different data mining algorithms are discussed. The neural network (NN) with multi-layer perceptron (MLP) algorithms produced the best results for all three IAQ sensors among all algorithms tested. The models built with data mining algorithms can serve as virtual IAQ sensors in buildings and be used for on-line monitoring and calibration of the IAQ sensors. The approach presented in this paper can be applied to HVAC systems in buildings beyond the type considered in this paper. (author)

Kusiak, Andrew; Li, Mingyang; Zheng, Haiyang [Department of Mechanical and Industrial Engineering, 3131 Seamans Center, The University of Iowa, Iowa City, IA 52242 - 1527 (United States)

2010-06-15

370

A comparison of radiative transfer models for predicting the microwave emission from soils  

Science.gov (United States)

Two general types of numerical models for predicting microwave emission from soils are compared-coherent and noncoherent. In the former, radiation in the soil is treated coherently, and the boundary conditions on the electric fields across the layer boundaries are used to calculate the radiation intensity. In the latter, the radiation is assumed to be noncoherent, and the intensities of the radiation are considered directly. The results of the two approaches may be different because of the effects of interference, which can cause the transmitted intensity at the surface (i.e., emissivity) to be sometimes higher and sometimes lower for the coherent case than for the noncoherent case, depending on the relative phases of reflected fields from the lower layers. This coupling between soil layers in the coherent models leads to greater soil moisture sampling depths observed with this type of model, and is the major difference that is found between the two types of models. In noncoherent models, the emissivity is determined by the dielectric constraint at the air/soil interface. The subsequent differences in the results are functions of both the frequency of the radiation being considered and the steepness of the moisture gradient near the surface. The calculations were performed at frequencies of 1.4 and 19.4 GHz and for two sets of soil profiles. Little difference was observed between the models at 19.4 GHz; and only at the lower frequency were differences apparent because of the greater soil moisture sampling depth at this frequency.

Schmugge, T. J.; Choudhury, B. J.

1980-01-01

371

The use of numerical flow models for the study of air streams and heat transfer in a room  

Energy Technology Data Exchange (ETDEWEB)

The air movement and heat transfer in a room are measured using a combined radiation/flow model. The flow calculation programme is based upon the 'CHAMPION' package, which resolves the equations governing twodimensional, static, turbulent flow by using the finite differential method. The heat transfer was calculated using a conventional programme. A number of the calculation results are given as an example. The experience gained from the software used and from using a self-developed radiation/flow program is discussed. 12 figs., 6 refs, 5 tabs.

Van Tongeren, P.J.; Lemaire, A.D.

1988-10-01

372

Estimation of Global Solar Radiation in Rwanda Using Empirical Models  

OpenAIRE

Understanding solar radiation data is essential for modeling solar energy systems. The purpose of the present study was to estimate global solar radiation on horizontal surface using sunshine-based models. Angström-type polynomials of first and second order have been developed from long term records of monthly mean daily sunshine hour values and measured daily global solar radiation on horizontal surface at Kigali, Rwanda. Coefficients of those polynomials were derived using least squ...

Safari, B.; Gasore, J.

2009-01-01

373

SHORT COMMUNICATION: Re-evaluation of the BIPM international standard for air kerma in 60Co gamma radiation  

Science.gov (United States)

A re-evaluation of the BIPM standard for air kerma in 60Co radiation has been made. The changes to the air-kerma rate determination arise from four sources: (i) the results of Monte Carlo calculations of correction factors for the standard; (ii) a re-evaluation of the correction factor for saturation; (iii) a new evaluation of the air volume of the standard using an experimental chamber of variable volume; (iv) the adoption of a new reference beam at the BIPM. The combined effect of these changes is an increase in the BIPM determination of air-kerma rate by the factor 1.0054 and a reduction of the relative standard uncertainty of this determination to 1.5 parts in 103. A full uncertainty budget is presented. The new standard is effective from 1 November 2007.

Burns, David T.; Allisy, Penelope J.; Kessler, Cecilia

2007-12-01

374

Subgrid-scale model for radiative transfer in turbulent participating media  

Energy Technology Data Exchange (ETDEWEB)

The simulation of turbulent flows of radiating gases, taking into account all turbulence length scales with an accurate radiation transport solver, is computationally prohibitive for high Reynolds or Rayleigh numbers. This is particularly the case when the small structures are not optically thin. We develop in this paper a radiative transfer subgrid model suitable for the coupling with direct numerical simulations of turbulent radiating fluid flows. Owing to the linearity of the Radiative Transfer Equation (RTE), the emission source term is spatially filtered to define large-scale and subgrid-scale radiation intensities. The large-scale or filtered intensity is computed with a standard ray tracing method on a coarse grid, and the subgrid intensity is obtained analytically (in Fourier space) from the Fourier transform of the subgrid emission source term. A huge saving of computational time is obtained in comparison with direct ray tracing applied on the fine mesh. Model accuracy is checked for three 3D fluctuating temperature fields. The first field is stochastically generated and allows us to discuss the effects of the filtering level and of the optical thicknesses of the whole medium, of the integral length scale, and of the cutoff wave length. The second and third cases correspond respectively to turbulent natural convection of humid air in a cubical box, and to the flow of hot combustion products inside a channel. In all cases, the achieved accuracy on radiative powers and wall fluxes is about a few percents.

Soucasse, L.; Rivière, Ph. [CNRS, UPR 288, Laboratoire EM2C, Grande Voie des Vignes, F-92290 Châtenay-Malabry (France); École Centrale Paris, Grande Voie des Vignes, F-92290 Châtenay-Malabry (France); Soufiani, A., E-mail: anouar.soufiani@em2c.ecp.fr [CNRS, UPR 288, Laboratoire EM2C, Grande Voie des Vignes, F-92290 Châtenay-Malabry (France); École Centrale Paris, Grande Voie des Vignes, F-92290 Châtenay-Malabry (France)

2014-01-15

375

Subgrid-scale model for radiative transfer in turbulent participating media  

International Nuclear Information System (INIS)

The simulation of turbulent flows of radiating gases, taking into account all turbulence length scales with an accurate radiation transport solver, is computationally prohibitive for high Reynolds or Rayleigh numbers. This is particularly the case when the small structures are not optically thin. We develop in this paper a radiative transfer subgrid model suitable for the coupling with direct numerical simulations of turbulent radiating fluid flows. Owing to the linearity of the Radiative Transfer Equation (RTE), the emission source term is spatially filtered to define large-scale and subgrid-scale radiation intensities. The large-scale or filtered intensity is computed with a standard ray tracing method on a coarse grid, and the subgrid intensity is obtained analytically (in Fourier space) from the Fourier transform of the subgrid emission source term. A huge saving of computational time is obtained in comparison with direct ray tracing applied on the fine mesh. Model accuracy is checked for three 3D fluctuating temperature fields. The first field is stochastically generated and allows us to discuss the effects of the filtering level and of the optical thicknesses of the whole medium, of the integral length scale, and of the cutoff wave length. The second and third cases correspond respectively to turbulent natural convection of humid air in a cubical box, and to the flow of hot combustion products inside a channel. In all cases, the achieved accuracy on radiative powers and wall fluxes is about a few percents

376

Optical tomographic in-air scanner for external radiation beam 3D gel dosimetry  

International Nuclear Information System (INIS)

Full text: Optical CT scanners are used to measure 3D radiation dose distributions in radiosensitive gels. For radiotherapy dose verification, 3D dose measurements are useful for verification of complex linear accelerator treatment planning and delivery techniques. Presently optical CTs require the use of a liquid bath to match the refractive index of the gel to minimise refraction of the light rays leading to distortion and artifacts. This work aims to develop a technique for scanning gel samples in free-air, without the requirement for a matching liquid bath. The scanner uses a He-Ne laser beam, fanned across the acrylic cylindrical gel container by a rotating mirror. The gel container was designed to produce parallel light ray paths through the gel. A pin phantom was used to quantify geometrical distortion of the reconstructed image, while uniform field exposures were used to consider noise, uniformity and artifacts. Small diameter wires provided an indication of the spatial resolution of the scanner. Pin phantom scans show geometrical distortion comparable to scanners using matching fluid baths. Noise, uniformity and artifacts were not found to be major limitations for this scanner approach. Spatial resolution was limited by laser beam spot size, typically 0.4 mm full width half maximum. A free-air optical CT scanner has been developed with the advantage of scanning without a matching fluid bath. Test results show it has potential to provide suitable quality 3D dootential to provide suitable quality 3D dosimetry measurements for external beam dose verification, while offering significant advantages in convenience and efficiency for routine use.

377

Transient air cooling thermal modeling of a PEM fuel cell  

Energy Technology Data Exchange (ETDEWEB)

Fuel cell utilization for automobile and residential applications is a promising option in order to help reduce environmental concerns such as pollution. However, fuel cell development requires addressing their dynamic behavior to improve their performances and their life cycle. Since the temperature distribution in the cell is known to be an important factor to the fuel cell's efficiency, a cooling device is often added to homogenize the temperature in the cell and to ensure temperature control. A 3D dynamic thermal model of a single fuel cell is presented in this work in order to study the temperature distribution in a fuel cell cooled from the bottom to the top with air. The model is governed by the thermal energy balance, taking into account the inlet gas humidity. The model is developed with the finite difference method and is implemented in the Matlab/Simulink environment. The validation is based on the performances of the ''NEXA'' fuel cell produced by Ballard Power Systems. The efficiency analysis of that air cooling device reveals that the cell temperature is directly linked to the current density and to the gas humidity - varying from 30 C at 5A to 80 C at 35A at low humidity. Moreover, the temperature non-uniformity in the stack is shown to be very high. As a result, temperatures are higher at the top part of the cell than at the bottom part, with a difference of up to a 5 C. Moreover the non-uniformity of the air cooling between the cells of the stack leads to large temperature variations, up to 8 C, from one cell to another. These temperature variations result in large voltage disparities between the cells, which reduce the total electrical power of the entire stack. (author)

Adzakpa, K.P.; Ramousse, J.; Dube, Y.; Akremi, H.; Agbossou, K. [Hydrogen Research Institute and Departement de genie electrique, Universite du Quebec a Trois-Rivieres, CP 500, Trois-Rivieres (QC) (Canada); Dostie, M.; Poulin, A.; Fournier, M. [LTE-Hydro-Quebec, 600 av. de la Montagne, Shawinigan (QC) (Canada)

2008-04-15

378

Mathematical modelling of radiative heat exchanges in Czochralski crystal pulling  

Science.gov (United States)

Reference is made to the model of Crowley (1983) describing the heat flow in Czochralski crystal pulling under the assumption that the surfaces of solid crystal and liquid meniscus are cooled by radiation to the atmosphere. An enhanced model is then proposed which takes into account the radiative heat exchanges between the atmosphere and the surfaces of the crystal, the meniscus, and the hot crucible wall. The general radiation optics principles used as the physical basis of the enhanced model are reviewed, and the new model is compared numerically with the Crowley model for the case of germanium pulling.

Stern, E. J.

1985-09-01

379

Simplified models of electromagnetic and gravitational radiation damping  

CERN Document Server

In previous work the authors analysed the global properties of an approximate model of radiation damping for charged particles. This work is put into context and related to the original motivation of understanding approximations used in the study of gravitational radiation damping. It is examined to what extent the results obtained previously depend on the particular model chosen. Comparisons are made with other models for gravitational and electromagnetic fields. The relation of the kinetic model for which theorems were proved to certain many-particle models with radiation damping is exhibited.

Kunze, M; Kunze, Markus; Rendall, Alan D.

2001-01-01

380

CFD Modeling of Air Pocket Transport in Conjunction with Spillway Conduits  

OpenAIRE

This paper focuses on simulations of enclosed air pocket movements in conjunction with bottom outlet operations. The critical velocity of water for air pocket transport in pipe is the minimal flow velocity for the air pocket start to move downstream. A numerical model is developed to simulate the critical velocity of air pocket transport in pipe flow and to discuss the impacts of tunnel slope, size of the air pocket and wall roughness. The computations are performed in FLUENT using Volume of ...

Liu, Ting; Yang, James

2011-01-01

381

Development of a hydrodynamic model for air-lift reactors  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this paper, a 1D hydrodynamic model has been developed for gas hold-up and liquid circulation velocity prediction in air-lift reactors. The model is based on momentum balance equations and has been adjusted to experimental data collected on a pilot plant reactor equipped with two types of gas dis [...] tributors and using water and water/butanol as the liquid phase. Different techniques of signal analysis have also been applied to pressure fluctuations in order to extract information about flow regimes and regime transitions. A good knowledge of the flow pattern is essential to establish adequate correlations for the hydrodynamic model.

E., Carvalho; E., Camarasa; L.A.C., Meleiro; R., Maciel Filho; A., Domingues; Ch., Vial; G., Wild; S., Poncin; N., Midoux; J., Bouillard.

2000-12-01

382

Modelling of the Through-air Bonding Process  

Directory of Open Access Journals (Sweden)

Full Text Available A computational fluid dynamics (CFD modelling ofthe through-air bonding process of nonwoven fabricproduction is reported in this article. In the throughairprocess, hot air is passed through the fibrous webto heat and melt polymer fibers. Molten polymersubsequently flows to the point of contact betweenany two fibers to produce a bond. Two differentmodelling strategies are adapted to produce acomprehensive understanding of the through-airbonding process. In macroscale modelling, a CFDmodel is developed treating the whole web as aporous media in order to investigate the effect ofprocess parameters. Results reveal that the timerequired to heat and melt the fibers decreases with theincreasing porosity of the web and the velocity of hotair. The CFD modelling technique is then used toanalyze the bonding process at a more fundamentallevel by considering the bonding of individual fibersat microscale. The effects of the fiber diameter,bonding temperature and contact angle between twofibers on the bonding time are investigated. Resultsshow that the time required to bond fibers is weaklyrelated to bonding temperature and fiber diameter.Fiber orientation angle, on the other hand, hassignificant effect on the progression of bondformation.

M. Hossain

2009-06-01

383

NASA Air Force Cost Model (NAFCOM): Capabilities and Results  

Science.gov (United States)

NAFCOM is a parametric estimating tool for space hardware. Uses cost estimating relationships (CERs) which correlate historical costs to mission characteristics to predict new project costs. It is based on historical NASA and Air Force space projects. It is intended to be used in the very early phases of a development project. NAFCOM can be used at the subsystem or component levels and estimates development and production costs. NAFCOM is applicable to various types of missions (crewed spacecraft, uncrewed spacecraft, and launch vehicles). There are two versions of the model: a government version that is restricted and a contractor releasable version.

McAfee, Julie; Culver, George; Naderi, Mahmoud

2011-01-01

384

Model air-supported drum-type homopolar generator  

International Nuclear Information System (INIS)

A single cylinder, drum-type homopolar generator has been designed and built for the purpose of developing a simple air support system for thin cylinder rotors operated at high surface velocities and significant radial drum growth. The model has an aluminum cylinder which is 0.32 cm thick, 25 cm in diameter, and 12.7 cm long. It is designed to operate at a peak current of 2500 A and to store a total of 40 kJ with a surface velocity of 305 m/sec

385

Measurement and modeling of external radiation during 1984 from LAMPF atmospheric emissions  

International Nuclear Information System (INIS)

An array of three portable, pressurized ionization chambers (PICs) measured short-term external radiation levels produced by air activation products from the Los Alamos Meson Physics Facility (LAMPF). The monitoring was at the closet offsite location, 700-900 m north and northeast of the source, and across a large, deep canyon. A Gaussian-type atmospheric dispersion model, using onsite meteorological and stack release data, was tested during their study. Monitoring results indicate that a persistent, local up-valley wind during the evening and early morning hours is largely responsible for causing the highest radiation levels to the northeast and north-northeast of LAMPF. Comparison of predicted and measured daily external radiation levels indicates a high degree of correlation. The model also gives accurate estimates of measured concentrations over longer periods of time

386

Radiation studies with a high-resolution mesoscale model  

International Nuclear Information System (INIS)

The paramaterization of radiation in general circulation models (GCMs) relies strongly on correctly representing the mean radiative properties over a typical grid size. The quality of the model's feedback between clouds and radiation would depend on the accuracy of this representation; this feedback is a key factor in determining the climate's behavior under various future scenarios. The use of a mesoscale model allows both clouds and radiation to receive a high-resolution treatment that can be free of the assumptions of overlapping and cloud fraction. To this end, the newest version of the Penn State/National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) has been upgraded to include a radiation package. Here the model is introduced and preliminary results are shown. Of particular interest are the domain-averaged properties of a cloud system as it evolves during one diurnal cycle

387

Two adaptive radiative transfer schemes for numerical weather prediction models  

OpenAIRE

Radiative transfer calculations in atmospheric models are computationally expensive, even if based on simplifications such as the ?-two-stream approximation. In most weather prediction models these parameterisation schemes are therefore called infrequently, accepting additional model error due to the persistence assumption between calls. This paper presents two so-called adaptive parameterisation schemes for radiative transfer in a limited area model: A perturbation scheme that expl...

Venema, V.; Schomburg, A.; Ament, F.; Simmer, C.

2007-01-01

388

Ontologies for the Integration of Air Quality Models and 3D City Models  

CERN Document Server

The holistic approach to sustainable urban planning implies using different models in an integrated way that is capable of simulating the urban system. As the interconnection of such models is not a trivial task, one of the key elements that may be applied is the description of the urban geometric properties in an "interoperable" way. Focusing on air quality as one of the most pronounced urban problems, the geometric aspects of a city may be described by objects such as those defined in CityGML, so that an appropriate air quality model can be applied for estimating the quality of the urban air on the basis of atmospheric flow and chemistry equations. In this paper we first present theoretical background and motivations for the interconnection of 3D city models and other models related to sustainable development and urban planning. Then we present a practical experiment based on the interconnection of CityGML with an air quality model. Our approach is based on the creation of an ontology of air quality models ...

Métral, Claudine; Karatzas, Kostas

2012-01-01

389

Sunspot Modeling: From Simplified Models to Radiative MHD Simulations  

Directory of Open Access Journals (Sweden)

Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

Rolf Schlichenmaier

2011-09-01

390

User's guide to the LIRAQ model: an air pollution model for the San Francisco Bay Area  

International Nuclear Information System (INIS)

The Livermore Regional Air Quality (LIRAQ) model comprises a set of computer programs that have been integrated into an easily used tool for the air quality planner. To assemble and modify the necessary data files and to direct model execution, a problem formulation program has been developed that makes possible the setup of a wide variety of studies involving perturbation of the emission inventory, changes to the initial and boundary conditions, and different choices of grid size and problem domain. In addition to describing the types of air quality problems for which the LIRAQ model may be used, this User's Guide provides detailed information on how to set up and conduct model simulations. Also included are descriptions of the formats of input data files so that the LIRAQ model may be applied to regions other than the San Francisco Bay Area

391

A dynamic thermal model for design and control of an 800-element open-air radio telescope  

Science.gov (United States)

In earlier work we have described the thermal modelling for design and control of a fully insulated, and sometimes ventilated, high precision radio telescope. For such an insulated telescope the modelling of the time-variable dynamic influence of the thermal environment (air, sky and ground radiation, insolation) is relatively simple. The modelling becomes however quite complex for an open-air radio telescope where each individual member of the reflector backup structure (BUS) and the support structure (fork or yoke) is exposed under a different and time-dependent aspect angle to the thermal environment, which applies in particular to solar radiation. We present a time-dependent 800-element thermal model of an open-air telescope. Using the IRAM 30-m radio telescope as the basic mechanical structure, we explain how the temperature induced, real-time pointing and reflector surface deformations can be derived when using as input the day of the year, the thermal environment, and the geographic position of the telescope and its changing pointing direction. Thermal modelling and results similar to those reported here can be used for radio telescope design and real-time control of pointing and surface adjustment of a telescope with active panels.

Bremer, Michael; Greve, Albert

2011-09-01

392

40 CFR Appendix W to Part 51 - Guideline on Air Quality Models  

Science.gov (United States)

...069(b). Office of Research...Development, Washington, D.C...Modeling, Washington, DC. Office of Air Quality...Administration, Washington, DC. Cadle...4-86-002. Office of Air Quality...You may also contact Joseph...

2010-07-01

393

40 CFR Appendix W to Part 51 - Guideline on Air Quality Models  

Science.gov (United States)

...Application of the Urban Airshed Model...Exhibition of the Air & Waste Management Association, Vancouver...of Housing and Urban Development...of the Air and Waste Management Association...located in rural or urban areas,...

2010-07-01

394

Environmental Radiation Effects on Mammals A Dynamical Modeling Approach  

CERN Document Server

This text is devoted to the theoretical studies of radiation effects on mammals. It uses the framework of developed deterministic mathematical models to investigate the effects of both acute and chronic irradiation in a wide range of doses and dose rates on vital body systems including hematopoiesis, small intestine and humoral immunity, as well as on the development of autoimmune diseases. Thus, these models can contribute to the development of the system and quantitative approaches in radiation biology and ecology. This text is also of practical use. Its modeling studies of the dynamics of granulocytopoiesis and thrombocytopoiesis in humans testify to the efficiency of employment of the developed models in the investigation and prediction of radiation effects on these hematopoietic lines. These models, as well as the properly identified models of other vital body systems, could provide a better understanding of the radiation risks to health. The modeling predictions will enable the implementation of more ef...

Smirnova, Olga A

2010-01-01

395

Research on Dependable Ionizing Radiation Protection based on Model i*  

Directory of Open Access Journals (Sweden)

Full Text Available The software’s unreliability mostly attributes to an erroneous analysis on the requirements done at the beginning. In this paper, we apply the tool of i* frame requirement modeling and build early requirement model against ionizing radiation. After finding out possible risks and corresponding solutions during the process of modeling analysis, we propose reasoning models against ionizing radiation. The radiation protection system  with  the  above models  can  figure out  the  purpose  of agents  related  to radiant source and provide normal service even when the environment software system is being interfered. It can serve the ecological and economical society with stability and development.  The model is divided into several sections. Section 1 gives the outline of the dependant software. Section 2 illustrates the  i* frame  technology. Section 3, 4 and 5 cover the topic of dependant security requirement analysis, SD&SR model on ionizing radiation respectively. Section 6 gives the conclusion.

Tan Hai

2013-07-01

396

Application of photoionization models based on radiative transfer and the Helmholtz equations to studies of streamers in weak electric fields  

International Nuclear Information System (INIS)

Recent advances in development of photoionization models in air based on radiative transfer and Helmholtz equations open new perspectives for efficient solution of nonthermal gas discharge problems involving complex geometries. Many practical applications require accurate modeling of streamer discharges developing in weak electric fields, in which the photoionization process significantly contributes to discharge dynamics. This paper (1) reports original studies, which demonstrate the validity and accuracy of the recently proposed photoionization models for studies of streamers in weak electric fields, and (2) introduces efficient boundary conditions for the photoinization models based on radiative transfer theory

397

Identification and weather sensitivity of physically based model of residential air-conditioners for direct load control: a case study  

Energy Technology Data Exchange (ETDEWEB)

In most electricity systems, the residential sector is one of the main contributors to system peaks. Hot and humid summer seasons lead to a significant proportion of the supplied power being used on air-conditioning (AC). In this work, we address the identification problem of the parameters of an aggregated elemental physically based model representing a housing unit with an AC system. The identification is done to validate the model using a pilothouse equipped with an independent air-conditioner system. An online maximum likelihood based-identification algorithm is developed. The required hardware and system instrumentation are detailed. A sensitivity analysis study of the model for variations in humidity and solar radiation is also reported. The results indicate that the physically based model succeeded to capture the effects of the outdoor conditions. (author)

El-Ferik, S.; Hussain, S.A.; Al-Sunni, F.M. [K.F.U.P.M., Dhahran (Saudi Arabia). Department of System Engineering

2006-08-15

398

3ARM: A Fast, Accurate Radiative Transfer Model For Use in Climate Models  

Science.gov (United States)

A new radiative transfer model combining the efforts of three groups of researchers is discussed. The model accurately computes radiative transfer in a inhomogeneous absorbing, scattering and emitting atmospheres. As an illustration of the model, results are shown for the effects of dust on the thermal radiation.

Bergstrom, R. W.; Kinne, S.; Sokolik, I. N.; Toon, O. B.; Mlawer, E. J.; Clough, S. A.; Ackerman, T. P.; Mather, J.

1996-01-01

399

Comparison of the standards for air kerma of the NIM and the BIPM for 60Co gamma radiation  

International Nuclear Information System (INIS)

A comparison of the standards for air kerma of the National Institute of Metrology of China and of the Bureau International des Poids et Mesures was carried out in 60Co gamma radiation at the BIPM in December 2001. The ratio of the NIM and the BIPM standards for air kerma is 0.9992, with a combined standard uncertainty of 0.0018. The degrees of equivalence between the NIM and the other participants in the ongoing key comparison BIPM.RI(I)-K1 have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. (authors)

400

Search for molecular bremsstrahlung radiation signals in Ku band with coincidental operations of radio telescopes with air shower detectors  

Directory of Open Access Journals (Sweden)

Full Text Available Microwave radiation from extensive air showers is expected to provide a new technique to observe UHECR. We insatlled and operate radio telescopes in Osaka and at Telescope Array site in Utah, USA. In Osaka, we are coincidentally operating two Ku band radio telescopes with an air shower array which consists of nine plastic scintillators with about 10?m separation. In Utah, we installed two telescopes just beside the Black Rock Mesa fluorescence detector (FD station of the Telescope Array experiment, and we operated the radio telescopes coincidentally with FD event triggers. We report the experimental setups and the results of these measurements.

Fukushima Masaki

2013-06-01