WorldWideScience
 
 
1

Developing of a New Atmospheric Ionizing Radiation (AIR) Model  

Science.gov (United States)

As a result of the research leading to the 1998 AIR workshop and the subsequent analysis, the neutron issues posed by Foelsche et al. and further analyzed by Hajnal have been adequately resolved. We are now engaged in developing a new atmospheric ionizing radiation (AIR) model for use in epidemiological studies and air transportation safety assessment. A team was formed to examine a promising code using the basic FLUKA software but with modifications to allow multiple charged ion breakup effects. A limited dataset of the ER-2 measurements and other cosmic ray data will be used to evaluate the use of this code.

Clem, John M.; deAngelis, Giovanni; Goldhagen, Paul; Wilson, John W.

2003-01-01

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

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

4

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

2009-03-01

5

SESAM - a model for calculating the radiation exposure associated with the release of pollutants contained in the exhaust air in the case of a multi-source situation  

International Nuclear Information System (INIS)

Within the scope of the research project St.Sch.645, sponsored by the German Federal Minister of Research and Technology (BMFT) a model and computer code called SESAM (calculation of radiation exposure by release of pollutants with the exhaust air in the case of a multi-source situation) was established, allowing to perform all the assessments of long-time exposure required for licensing - as e.g. evaluation of the maximum individual radiation exposure of the different organs at the most unfavorable point of reference - associated with the environmental impact of several nuclear sources of release - as e.g. several units of a nuclear power plant, different sources of a waste management center, or also consideration of the pre-existing exposures of a site caused by nuclear sources. The basis of this multi-source model SESAM are the models for calculating the exposure in the environment of nuclear facilities for the pathways external gamma radiation from the cloud, external beta radiation from the cloud, gamma radiation from material deposited on the ground, inhalation and ingestion, as well as the data material, as e.g. dose constants and radioecological conversion factors (kg 1 and kg 2) for critical groups of the popualation, specified in the German guideline Principles for Calculating the Exposure Caused by the Release of Radioactive Material with the Exhaust Air. (orig./HP)

1980-01-01

6

Air dispersion modelling template  

…:50,000 scale). 1.3 POLLUTANTS AND AIR QUALITY GUIDELINES A list of pollutants modelled. The pollutants under consideration in the assessment should be clearly identified, including chemical speciation (e.g. oxides of nitrogen, halogenated compounds). Discussion of relevant air quality standards and…

7

Gamma radiation energy absorption in air  

International Nuclear Information System (INIS)

An algorithm for calculating absorbed energy of gamma radiation from a point isotropic monohromatic ?-pulsed gamma source placed in a homogeneous air medium is given. The dependence for the mean time of gamma radiation absorbed energy variation on gamma quantum energy is obtained

1986-10-01

8

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

9

Air dispersion modelling template  

…Unit 4 Air dispersion modelling report requirements Parameter Units Stack Location (NGR) Stack height (m) Pollutant emission rate (g/s) 1, 2 Exit diameter (m) Exit temperature (K, C) Efflux velocity (actual), and/or (m/s) Volumetric flow rate (actual) (m3 /s) 1. Note that pollutant emission rate is often…

10

Sensitivity of contrail cirrus radiative forcing to air traffic scheduling  

Science.gov (United States)

Air traffic effects high cloudiness and therefore the Earth's radiation budget by producing contrail cirrus. Contrail cirrus comprise of line-shaped contrails and irregularly shaped ice clouds that originate from them. The warming effect of contrail cirrus is disproportionally large at night, since at daytime the cooling due to the short wave cloud albedo effect acts toward compensating the long wave warming effect. Therefore it has been suggested to restrict air traffic to daytime in order to reduce its climate impact. The potential for reducing the contrail cirrus radiative forcing by shifting air traffic to daytime depends on the diurnal cycle of contrail cirrus coverage which is in turn determined by the diurnal cycle of air traffic and the contrail cirrus lifetimes. Simulations with a global atmospheric general circulation model indicate that the annual mean contrail cirrus coverage may be almost constant over the day even in areas where air traffic is close to zero at night. A conceptual model describing the temporal evolution of contrail cirrus coverage reveals that this is due to the large variability in contrail cirrus lifetimes in combination with the spreading of contrail cirrus. This large variability of lifetimes is consistent with observational evidence but more observations are needed to constrain the contrail lifetime distribution. An idealized mitigation experiment, shifting nighttime flights to daytime, indicates that contrail cirrus radiative forcing is not significantly changed.

Newinger, Christina; Burkhardt, Ulrike

2012-05-01

11

Air-crew radiation dosimetry - last development  

International Nuclear Information System (INIS)

Exposure to cosmic radiation increases rapidly with the altitude. At the flight levels of commercial aircraft it is of the order of several ?Sv per hour. The most of air-crew are exposed regularly to the effective dose exceeding 1 mSv per year, the limit of exposure of non-professionals defined in ICRP 60 recommendation. That is why this problem has been intensively studied from many aspects since the beginning of 90's. This contribution summarises new developments in the field during last two years. First, new international activities are presented, further, new achievement obtained mainly in the author's laboratory are presented and discussed. (authors)

2001-11-01

12

Influence of atmospheric rainfall to ? radiation Kerma rate in surface air  

International Nuclear Information System (INIS)

Objective: To investigate the influence rule of the atmospheric Rainfall to the ? radiation Kerma rate in surface air in order to revise the result of its measurement during rainfall. Methods: The influence factors of rainfall to the measurement of the ? radiation Kerma rate in air were analyzed and then the differential equation of the correlation factors was established theoretically, and by resolving the equation, the mathematical model Was obtained. The model was discussed through several practical examples. Results: The mathematical model was coincided with the tendency of curve about the measured data on the influence rule of rainfall to the ? radiation Kerma rate in surface air. Conclusion: By using the theoretical formula in this article which is established to explain the relationship between the rainfall and the ? radiation Kerma rate in surface air, the influence of rainfall to the ? radiation Kerma rate in surface air could be correctly revised. (authors)

2009-04-01

13

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.

1995-01-01

14

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

15

New radiation limits and air crew exposure  

International Nuclear Information System (INIS)

Commercial aircraft have optimum cruising speed of 800 - 900 km/h and the cruising altitude near 13 km.The flight paths are assigned according to airway corridors and safety requirements.The relatively high dose-equivalent rates at cruising altitudes near 13 km (about 0.5-2 mSv/h, and the shielding effect of the atmosphere corresponds to about 2 M of water) can cause exposures greater than 5 mSv/y, for a crew with full-time flight (500-600 h/y).The radiation exposure of the crew in commercial air traffic has been studied for the associations of the crews and airline management and published, and regulatory authorities are slowly accepting the fact that there indeed is a problem which needs investigations and protective regulation

1999-01-01

16

Solar radiation models - review  

Directory of Open Access Journals (Sweden)

Full Text Available In the design and study of solar energy, information on solar radiation and its components at a given location is very essential. Solar radiation data are required by solar engineers, architects, agriculturists and hydrologists for many applications such as solar heating, cooking, drying and interior illumination of buildings. For this purpose, in the past, several empirical correlations have been developed in order to estimate the solar radiation around the world. The main objective of this study is to review the global solar radiation models available in the literature. There are several formulae which relate global radiation to other climatic parameters such as sunshine hours, relative humidity and maximum temperature. The most commonly used parameter for estimating global solar radiation is sunshine duration. Sunshine duration can be easily and reliably measured and data are widely available.

M. Jamil Ahmad, G.N. Tiwari

2010-05-01

17

Blackbody Radiation Spectrum Model  

Science.gov (United States)

The Blackbody Radiation Spectrum model shows six fixed-temperature curves between Tmin and Tmax and a red variable-temperature curve that can be adjusted using a slider. The wavelength is measured in nm (nanometer) and the intensity is measured in W.e-5 / (m2.nm). Users can adjust Tmin and Tmax to change the temperature range that is displayed. The Blackbody Radiation Spectrum was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double click the ejs_ntnu_BlackbodyRadiationSpectrum.jar file to run the program if Java is installed.

Hwang, Fu-Kwun

2009-08-22

18

Geostatistical models for air pollution  

International Nuclear Information System (INIS)

The objective of this paper is to present geostatistical models applied to the spatial characterisation of air pollution phenomena. A concise presentation of the geostatistical methodologies is illustrated with practical examples. The case study was conducted in an underground copper-mine located on the southern of Portugal, where a biomonitoring program using lichens has been implemented. Given the characteristics of lichens as indicators of air pollution it was possible to gather a great amount of data in space, which enabled the development and application of geostatistical methodologies. The advantages of using geostatistical models compared with deterministic models, as environmental control tools, are highlighted. (author)

2000-06-01

19

Air dispersion modelling template  

…location and dimensions of all buildings included in the model (i.e. NGR, height, width, rotation). A site plan showing the location and relative orientation of buildings and their dimensions should be included. 1.11 SENSITIVITY ANALYSIS This should include a discussion and quantification of model sensitivity…

20

ATHENA radiation model  

Energy Technology Data Exchange (ETDEWEB)

The ATHENA computer program has many features that make it desirable to use as a space reactor evaluation tool. One of the missing features was a surface-to-surface thermal radiation model. A model was developed that allows any of the regular ATHENA heat slabs to radiate to any other heat slab. The view factors and surface emissivities must be specified by the user. To verify that the model was properly accounting for radiant energy transfer, two different types of test calculations were performed. Both calculations have excellent results. The updates have been used on both the INEL CDC-176 and the Livermore Cray. 7 refs., 2 figs., 6 tabs.

Shumway, R.W.

1987-10-01

 
 
 
 
21

ATHENA radiation model  

International Nuclear Information System (INIS)

The ATHENA computer program has many features that make it desirable to use as a space reactor evaluation tool. One of the missing features was a surface-to-surface thermal radiation model. A model was developed that allows any of the regular ATHENA heat slabs to radiate to any other heat slab. The view factors and surface emissivities must be specified by the user. To verify that the model was properly accounting for radiant energy transfer, two different types of test calculations were performed. Both calculations have excellent results. The updates have been used on both the INEL CDC-176 and the Livermore Cray. 7 refs., 2 figs., 6 tabs

1987-01-01

22

Air dispersion modelling template  

…This is usually related to the relevant land-use classification(s) however the values of parameters (e.g. roughness length, albedo, Bowen ratio/Priestly-Taylor parameter) describing the classifications used in the model should also be reported. 1.9 TREATMENT OF TERRAIN The applicant should justify…

23

Air dispersion modelling template  

…and relative orientation of buildings and their dimensions should be included. 1.11 SENSITIVITY ANALYSIS This should include a discussion and quantification of model sensitivity to meteorological data (e.g. different met sites, inter-annual variation, surface characteristics), emission parameters (stack…

24

Office of radiation and indoor air: Program description  

Energy Technology Data Exchange (ETDEWEB)

The goal of the Environmental Protection Agency`s (EPA) Office of Radiation and Indoor Air is to protect the public and the environment from exposures to radiation and indoor air pollutants. The Office develops protection criteria, standards, and policies and works with other programs within EPA and other agencies to control radiation and indoor air pollution exposures; provides technical assistance to states through EPA`s regional offices and other agencies having radiation and indoor air protection programs; directs an environmental radiation monitoring program; responds to radiological emergencies; and evaluates and assesses the overall risk and impact of radiation and indoor air pollution. The Office is EPA`s lead office for intra- and interagency activities coordinated through the Committee for Indoor Air Quality. It coordinates with and assists the Office of Enforcement in enforcement activities where EPA has jurisdiction. The Office disseminates information and works with state and local governments, industry and professional groups, and citizens to promote actions to reduce exposures to harmful levels of radiation and indoor air pollutants.

1993-06-01

25

Office of radiation and indoor air: Program description  

International Nuclear Information System (INIS)

The goal of the Environmental Protection Agency's (EPA) Office of Radiation and Indoor Air is to protect the public and the environment from exposures to radiation and indoor air pollutants. The Office develops protection criteria, standards, and policies and works with other programs within EPA and other agencies to control radiation and indoor air pollution exposures; provides technical assistance to states through EPA's regional offices and other agencies having radiation and indoor air protection programs; directs an environmental radiation monitoring program; responds to radiological emergencies; and evaluates and assesses the overall risk and impact of radiation and indoor air pollution. The Office is EPA's lead office for intra- and interagency activities coordinated through the Committee for Indoor Air Quality. It coordinates with and assists the Office of Enforcement in enforcement activities where EPA has jurisdiction. The Office disseminates information and works with state and local governments, industry and professional groups, and citizens to promote actions to reduce exposures to harmful levels of radiation and indoor air pollutants

1993-01-01

26

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

27

Frontiers in air quality modelling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, we fi...

Colette, A.; Bessagnet, B.; Meleux, F.; Roui?l, L.

2013-01-01

28

Environmental Protection Agency, Office of Air and Radiation  

Science.gov (United States)

... and light trucks Fuels and fuel additives Fuel economy Heavy trucks and buses Motorcycles Ocean-going Vessels ... mission is to protect the public and the environment from the risks of radiation and indoor air ...

29

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

30

The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing.  

Science.gov (United States)

Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect, although one that is currently small compared to that induced by other sources of human emissions. However, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact of aircraft radiative forcing on climate. Contrails have an effect on the Earth's energy balance similar to that of high thin ice clouds. Their trapping of outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) is partly compensated by their reflection of incoming solar radiation (negative radiative forcing). On average, the longwave effect dominates and the net contrail radiative forcing is believed to be positive. Over daily and annual timescales, varying levels of air traffic, meteorological conditions, and solar insolation influence the net forcing effect of contrails. Here we determine the factors most important for contrail climate forcing using a sophisticated radiative transfer model for a site in southeast England, located in the entrance to the North Atlantic flight corridor. We find that night-time flights during winter (December to February) are responsible for most of the contrail radiative forcing. Night flights account for only 25 per cent of daily air traffic, but contribute 60 to 80 per cent of the contrail forcing. Further, winter flights account for only 22 per cent of annual air traffic, but contribute half of the annual mean forcing. These results suggest that flight rescheduling could help to minimize the climate impact of aviation. PMID:16778887

Stuber, Nicola; Forster, Piers; Rädel, Gaby; Shine, Keith

2006-06-15

31

Radiation exposure and air travel: should we worry?  

Science.gov (United States)

With the federal government introducing new advanced imaging scanners at airports, the traveling public has become concerned about the radiation exposure they may receive when passing through scanners as well as during flight. This article offers a primer on radiation and the extent to which exposure from various sources can affect health. It also provides advice for physicians whose patients may have concerns about radiation exposure during air travel. PMID:21736206

Hansen, Ronnell; Hansen, Elisa

2011-06-01

32

Fuzzy control model and simulation of supply air system in a test rig of low-temperature hot-water radiator system  

Energy Technology Data Exchange (ETDEWEB)

This paper proposes a typical multi-variable, large time delay and nonlinear system, self-extracting rules fuzzy control (SERFC) method to maintain a stable temperature value in a built environment chamber with supply air system and hot-water system. The parameters of the transfer functions in every control loop were identified by experimental data in a format of time sequences obtained from the experiment of dynamical responding performance. Fuzzy control simulations were implemented based on adjustment of the supply air system and hot-water system by SERFC. The simulation results show that SERFC for environment chamber has satisfied performance. There is no higher overshoot and stable error. The work presented in here can be used to deal with those complex thermal processes with difficulties in modeling of fuzzy control rules and provide a foundation for further application of fuzzy control in HVAC system. (author)

Lu, Zhen; Zhang, Jili [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024 (China); Chen, Yongpan; Zhao, Tianyi [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin (China); Liu, Hui [Beijing Siemens Cerberus Electronics Ltd, Beijing (China)

2010-03-15

33

The importance of maximum air temperature in the parameterisation of solar radiation in Nigeria  

Energy Technology Data Exchange (ETDEWEB)

Using existing and new empirical model equations to analyse available data for nine stations located in different geographical and climatic zones in Nigeria, it is clearly demonstrated that maximum air temperature is an important climatological parameter which should be used in solar radiation modelling in Nigeria. It is also shown that seasonal variations in the values of the model parameters are significant. Preliminary investigations are also reported which show that (1) a slight modification of the Swartman-Ogunlade formulae improves their applicability to Nigerian stations, and (2) maximum air temperature and relative humidity can be used together (to the exclusion of sunshine duration) to predict solar radiation with satisfactory accuracy. (Author)

Ododo, J.C.; Sulaiman, A.T.; Ogbu, F.A. [Federal Univ. of Technology, Yola (Nigeria); Aidan, J. [Kashim Ibrahim Coll. of Education, Maiduguri (Nigeria); Yuguda, M.M. [Federal Coll. of Education, Yola (Nigeria)

1995-12-01

34

Refined photolysis rates for advanced air quality modeling systems  

Energy Technology Data Exchange (ETDEWEB)

Accurate modeling of photochemistry is critical and fundamental to reducing the uncertainty in air quality model predictions. Almost all chemical reactions in the atmosphere are initiated by the photodissociation of a number of trace gases. A direct measure of this photodissociation is the photolysis rate. Many current air quality models use crude approximations to calculate the photolysis rates with little consideration of variations in vertical profiles of temperature, ozone concentrations, aerosol concentrations, cloud parameters, and spectral surface albedo. However, more accurate estimates of photolysis rates can be produced with advanced radiative transfer modeling techniques and data measurements. A refined module is being developed to simulate the actinic flux and photolysis rates of tropospheric species for air quality and tropospheric photochemistry modeling. The module will combine advanced radiative transfer models with explicit computations of photolysis rates using detailed information on (1) prevailing atmospheric conditions during simulation episodes, (2) satellite ozone and cloud coverage data, and (3) detailed characteristics of clouds, aerosols and surface albedo.

Roselle, S.J.; Schere, K.L.; Pleim, J.E. [National Oceanic and Atmospheric Administration, Research Triangle Park, NC (United States); Hanna, A.F.; Jang, J.C.C. [MCNC-North Carolina Supercomputing Center, Research Triangle Park, NC (United States); Lu, Y. [Environmental Protection Agency, Research Triangle Park, NC (United States)

1996-12-31

35

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

36

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

1993-07-26

37

Plasma Properties Induced in Air by Alpha Radiation  

International Nuclear Information System (INIS)

The plasma characteristics of partially dissociated and ionized air due to alpha emissions from a radioisotope surface material have been investigated. Preliminary estimates of average electron energy, electron attachment coefficient, electron- ion recombination coefficient, distribution of equilibrium electron density, plasma frequency, electrical conductivity, and dielectric properties normal to a radioactive surface have been made for alpha-radiated air. The analytical procedure is based on Rutherford scattering theory from which it was found that the average kinetic energy of secondary electrons is 113.5 eV, that of tertiary electrons is 8.2 eV, and that of the total number of free electrons is 43.2 eV. The temporal average electron energy in room temperature air is estimated to be approximately 20 eV, and the dependence of electron attachment coefficient and electron-ion recombination coefficient on average electron energy is recognized. Based on this electron energy dependence, the attachment coefficient was found to be negligible and the recombination coefficient (dissociative) was determined from the thermal plasma experiments of Biondi and Brown as a function of air density. Estimates of average electron density through the ionized air layer adjacent to a polonium-210 surface coating of 2 mCi/in2 were computed to be 109 to 1010 cm3 and its graded distribution normal to the surface was estimated from which its plasma frequency distribution was found. The electron collisional cross-section was determined to be a weak function of electron kinetic energy and the distribution of electrical conductivity and permittivity through the plasma could then be computed, from which it was predicted that a measurable interaction with an electromagnetic wave propagating through an alpha-generated air plasma may occur. An experimental programme was undertaken. The test results show: (1) the average electron density of alpha-bombarded air is 109-1010 cm-3 ; (2) electron attachment in alpha-radiated air is, as assumed, apparently negligible, and (3) dissociative recombination coefficient estimated for an alpha-radiation air plasma is apparently of the correct order of magnitude. The conclusions of this study are that air at normal temperature may be induced by alpha radiation to attain electrical conductivity equivalent to a thermal air plasma at a temperature of approximately 2500°K and that the electrical conductivity of many thermal plasmas (depending upon their composition, ionization potential, basic electron density level, etc.) may be increased by exposure to large quantities of alpha radiation. (author)

1966-10-01

38

Model test of air-exchange efficiency  

Energy Technology Data Exchange (ETDEWEB)

The mixing-air flow pattern was studied. Three air flows were tested using the tracer gas technique and decay method. The indices of air exchange efficiency were calculated, namely: overall air-exchange efficiency and room-air mean age for the whole room; local ventilation indices and local mean ages of air at 10 points distributed throughout the room. Experiments were carried out in both isothermal and nonisothermal conditions. Based on the theory of similarity requirements, a reduced-scale model, geometrically similar to the laboratory test room, was built. Air flows and temperature differences were calculated for the model tests in order to make them comparable with the full scale, and the tests were repeated. The objective of the study was to determine the relation between the air-exchange efficiency indices obtained in the model and on the full scale.

Klobut, K.

1987-01-01

39

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

40

Air travel and radiation risks - review of current knowledge  

International Nuclear Information System (INIS)

Aircrew and passengers are exposed to cosmic radiation, in particular when travelling routes close to the poles and in high altitudes. The paper reviews current radiation measurement and estimation approaches as well as the actual level of cosmic radiation that personnel and travellers receive and summarizes the available epidemiological evidence on health effects of cosmic radiation. On average, German aircrew is exposed to les than 5 mSv per annum, and even frequent travellers only rarely reach values above 1 mSv/year. Cohort studies among aircrew have found very little evidence for an increased incidence or mortality of radiation-associated cancers. Only malignant melanoma rates have consistently found to be increased among male aircrew. Socioeconomic and reproductive aspects are likely to contribute to the slightly elevated breast cancer risk of female aircrew. Cytogenetic studies have not yielded consistent results. Based on these data overall risk increases for cancer among occupationally exposed aircrew appear unlikely. This also applies to air travellers who are usually exposed to much lower radiation levels. Occasional air travel during pregnancy does not pose a significant radiation risk, but further considerations apply in this situation. The currently available studies are limited with regard to methodological issues and case numbers so that a continuation of cohort studies in several European countries is being planned. (orig.)

2004-01-01

 
 
 
 
41

Radiation hardening of polyester compostons noninhibited by air oxygen  

International Nuclear Information System (INIS)

The results of investigation into compositions on the base of unsaturated polyesters conducted for obtaining non-inhibited by air oxygen coatings effectively hardened under ionizing radiation particularly ?-radiation of 60Co as well as accelerated electrons of 5 MeV linac are presented. The effect of structure of acidic modifying reagents on effectiveness of radiation hardening of styrene polyester solutions is studied. Hardened polyesters are stated to be characterized by relatively high rate of copolymerization with styrene at comparatively small radiation doses. Presence of phthalic and chlorendic anhydrides links in polyester chain results in noticeable decrease of inhibiting effect of oxygen. Chlorendic anhydride is shown to be most effective acidic reacting agent. In its presence inhibition with air oxygen is suppressed at negligible radiation dose (0.02 MGy). Parameters of radiation-hardened polyesters noticeably increase similar characteristics of material prepared using an ordinary method by means of initiators of radical polymerization. Hardening is completed at radiation doses corresponding to limiting hardness of coatings that is a peculiar feature of the studied composition

1984-01-01

42

Propagation speed of ?-radiation in air  

International Nuclear Information System (INIS)

To perform such measurements the availability of a gamma radiation source in which two ?-rays are emitted simultaneously in opposite directions -as already used(5,6) as well as applied in the present case- turns out to be essential to the feasibility of the experiment, as far as no reflection techniques could be used. Such suitable source was the positron emitter 22Na placed in a metal container in which the positrons are stopped and annihilated when reacting with the medium electrons, in such way originating -as it is very well established from momentum/energy conservation laws(7)- two ?-rays, energy 511 KeV each, both emitted simultaneously in opposite directions. In all these previous experiments were used photomultiplier detectors coupled to NaI(Tl) crystal scintillators, which have a good energy resolution but a deficient time resolution for such purposes. Presently, as an innovatively improvement, were used BaF2 and CsF crystal scintillators which display a much better time resolution. (author)

2008-01-01

43

An offset model radiation calorimeter  

International Nuclear Information System (INIS)

An offset model calorimeter specially designed for FEL experiments on EPA-74 is presented. The calorimeter is substantially capable of deducting the temperature drift because it consists of two hollow thin wall cone graphite absorbers and two thermistors. The device is capable of measuring the microwave radiated energy, microwave waveform and radiated frequency simultaneously. The authors have measured a 20 mJ of microwave radiated energy, 1MW of radiated power and 33 GHz of radiated frequency in FEL experiments on EPA-74 without a guide magnetic field by using the calorimeter

1992-05-25

44

[Radiation exposure and air quality aboard commercial airplanes].  

Science.gov (United States)

The amount of exposure to cosmic radiation during air travel is next to a number of additional factors mainly dependent on the flight level of the aircraft. Flying in an altitude of 41,000 feet equaling 12,800 meters the amount of radiation exposure is of course considerable higher than on the ground. The overall exposure of flying personnel to cosmic radiation flying about 600-700 hours per year can be estimated between 3 and 6 mSv (300-600 mrem). According to the flight hours of passengers, the radiation exposure is much lower and can be neglected for most of the travelers final judgement about the possible risks for flying personnel as far as a higher incident of malignant tumors is concerned has not jet been finally made. Talking of cabin air quality compromises have to be made and thus the well-being of the passengers can be negatively influenced. Air pressure and oxygen partial pressure correspond to an altitude of 2400 meters (8,000 feet) above sea level with possible consequences to the cardiopulmonary system. Increased level of ozone can lead to respiratory problems of the upper airways, increased carbon dioxide may cause hyperventilation. The mucous membranes of the respiratory tract are dried out due to the extremely low humidity of the cabin air. Smoking during flight results in an increase of the nicotine blood levels even in passengers sitting in the non-smoking areas. In modern aircraft the fresh-air flow cannot be regulated individually any more, this may lead to an insufficient circulation of used air in relation to fresh air and could cause the phenomena of hanging smoke. There has always been the idea that there is an increased risk for passengers for acquiring infectious diseases. However this is not the case. Modern HEPA-filter prevent an accumulation even of the smallest particles including bacteria and viruses within the recirculation flow in the cabin air. The overall risk of getting an infectious disease is significantly lower than in other ground operated public means of transportation. PMID:10568250

Bergau, L

1999-10-01

45

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 ("6"0Co, "2"5"2Cf) 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

1995-11-20

46

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

1999-01-01

47

Ultraviolet radiation and air contamination during total hip replacement  

International Nuclear Information System (INIS)

Ultraviolet (uv) radiation of the operating room was assessed bacteriologically in an open randomized study of 30 total hip procedures. Volumetric air-sampling demonstrated that the number of colony forming units (cfu m-3) were significantly reduced (P less than 0.001) by uv light, both close to the wound and in the periphery of the operating room. No adverse effects of the uv-irradiation were observed either in the patients or the staff. In operating rooms fitted with a zonal ventilation system and with an air change rate of about 70 h-1, the addition of uv irradiation during surgery may achieve ultra clean air. However, in conventionally ventilated operating rooms uv-irradiation alone is probably not sufficient to do so

1986-01-01

48

Air quality modeling studies in Japan clean air program; JCAP ni okeru taiki model kenkyu  

Energy Technology Data Exchange (ETDEWEB)

The air quality modeling study in Japan Clean Air Program has been made with the aim of: (1) Developing the motor vehicle emission inventory model that can estimate the influence of fuel properties and vehicle technologies on emissions. (2) Evaluating air quality in both urban area and the street canyon. (3) Constructing the secondary particulate formation model for urban air quality model. Preliminary modeling studies are conducted to understand the influence of motor vehicle emissions on air quality in Tokyo urban area. It has been shown by the results that the reduction of NO{sub x} emission is effective in improving the urban ozone and NO{sub x} concentration. (author)

Kobayashi, S. [Petroleum Energy Center, Tokyo (Japan); Yamazaki, S. [Toyota Central Research and Development Labs., Inc., Aichi (Japan); Suzuki, K. [Idemitsu Kosan Co. Ltd., Tokyo (Japan)

2000-05-01

49

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

2013-09-25

50

OpenAIRE - Data Model Specification  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The OpenAIRE web site will offer functionalities for administrators, anonymous and registered users to manage an Information Space of FP7-funded open access publications. The aim of this document is to describe the conceived structure and semantics of this Information Space, i.e., the Open AIRE data model, by providing an abstract definition of its main entities and the relationships between them. In this definitional process, the intended interaction (Task 7.2) between the OpenAIRE Informati...

Manghi, Paolo

2010-01-01

51

Air quality modeling in Warsaw Metropolitan Area  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

52

To the air crew exposure to cosmic radiation  

International Nuclear Information System (INIS)

To analyse air crew exposure to cosmic radiation, both experimentally and by means of the calculation with the goal to assure the individual assessment of this type of exposure. The experimental measurements were realised by means of several different equipments, both passive and active, to characterise all components of radiation fields on board aircraft. The calibration experiments in the on-Earth high energy particle reference fields were also regularly repeated since 1993. The most of measurements was performed in the periods between 1991 and 1993, and, subsequently, during 1999. The calculation of air crew exposure level on board was performed by means of the transport code CARI, in the versions 3N (H*(10)-ambient dose equivalent is calculated), and/or 5E (E-effective dose is calculated). The experimental data directly measured in the period 1991 to 1993 were interpreted on the base of a detector energy response, the results of calibration experiments in high energy reference fields and, also, taking into account independent data on particle's energy spectra and their energy deposition in the human body. Complete set of data obtained in the period mentioned was treated using a regression analysis to get the generalised dependence of exposure level on the flight altitude in the period of rather low solar activity. The experimental data directly measured during the series realised during 1999 were interpreted in the same way and they were compared with the data calculated for the same flight profile by means of the code CARI in its version 5E. It was found that the experimental data are in both cases about 20-25% higher than the calculated ones. The experimentally measured ambient dose equivalent rate vary between 4 and 8 ?Sv per hour for flight altitudes between 10 and 13 km. The code CARI 5E was also used to estimate the annual exposure of the air crew of a small company for the year 1998. Some model assumptions concerning the flight altitudes distributions have been adopted, their influence would compensate the underestimation observed when calculated values are compared with the experimental ones. It was found that, for the average number of flight hours about 450, three maxima can be distinguished in the effective dose distribution. The highest one (about 2.5 mSv) corresponds to the personnel flying frequently on northatlantic flights. The average annual effective dose was 1.54 mSv, when exposures below 1 mSv are omitted, it decreases to 1.85 mSv. Both figures are higher than it is usual for the most of other categories of occupationally exposed persons. We believe that the estimated values of effective doses are correct within ±25%, which fulfill the requirements on a personal dosimetry system. Both calculation and experimental approaches can be improved, we continue our effort in both directions. (author)

2000-05-01

53

Mathematical modeling of photochemical air pollution  

International Nuclear Information System (INIS)

This paper summarizes the key elements of a project directed at developing a comprehensive mathematical model capable of describing the formation and transport of chemically reacting species in the turbulent planetary boundary layer. The model is intended for routine application in the design and evaluation of urban-scale air pollution control strategies. Some examples illustrating the use of the model in the South Coast Air Basin of Southern California are presented

1979-11-15

54

Radiative Transfer Modeling for the CLAMS Experiment.  

Science.gov (United States)

Spectral and broadband radiances and irradiances (fluxes) were measured from surface, airborne, and spaceborne platforms in the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) campaign. The radiation data obtained on the 4 clear days over ocean during CLAMS are analyzed here with the Coupled Ocean-Atmosphere Radiative Transfer (COART) model. The model is successively compared with observations of broadband fluxes and albedos near the ocean surface from the Clouds and the Earth's Radiant Energy System (CERES) Ocean Validation Experiment (COVE) sea platform and a low-level OV-10 aircraft, of near-surface spectral albedos from COVE and OV-10, of broadband radiances at multiple angles and inferred top-of-atmosphere (TOA) fluxes from CERES, and of spectral radiances at multiple angles from Airborne Multiangle Imaging Spectroradiometer (MISR), or “AirMISR,” at 20-km altidude. The radiation measurements from different platforms are shown to be consistent with each other and with model results. The discrepancies between the model and observations at the surface are less than 10 W m-2 for downwelling and 2 W m-2 for upwelling fluxes. The model-observation discrepancies for shortwave ocean albedo are less than 8%; some discrepancies in spectral albedo are larger but less than 20%. The discrepancies between low-altitude aircraft and surface measurements are somewhat larger than those between the model and the surface measurements; the former are due to the effects of differences in height, aircraft pitch and roll, and the noise of spatial and temporal variations of atmospheric and oceanic properties. The discrepancy between the model and the CERES observations for the upwelling radiance is 5.9% for all angles; this is reduced to 4.9% if observations within 15° of the sun-glint angle are excluded.The measurements and model agree on the principal impacts that ocean optical properties have on upwelling radiation at low levels in the atmosphere. Wind-driven surface roughness significantly affects the upwelling radiances measured by aircraft and satellites at small sun-glint angles, especially in the near-infrared channel of MISR. Intercomparisons of various measurements and the model show that most of the radiation observations in CLAMS are robust, and that the coupled radiative transfer model used here accurately treats scattering and absorption processes in both the air and the water.

Jin, Zhonghai; Charlock, Thomas P.; Rutledge, Ken; Cota, Glenn; Kahn, Ralph; Redemann, Jens; Zhang, Taiping; Rutan, David A.; Rose, Fred

2005-04-01

55

OpenAIRE - Data  Model  Specification  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The   OpenAIRE   web   site   will   offer   functionalities   for   administrators,   anonymous   and   registered  users  to  manage  an  Information  Space  of  FP7-­funded  open  access  publications.   The   aim   of   this   document   is   to   describe   the   conceived   structure   and   semantics   of   this   Information  Space,  i.e.,  the  Open  AIRE  data  model,  by  providing  an  abstract  definition  of   its  main  ent...

Manghi, Paolo

2010-01-01

56

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

57

Lean hydrogen-air-steam mixture combustion models  

International Nuclear Information System (INIS)

Hydrogen combustion computer models are needed to evaluate the consequences of deliberate or accidental ignition of hydrogen-air-steam mixtures with a reactor containment building. Phenomenological flame-propagation models for hydrogen-air-steam mixture deflagrations are described. The models treat the concentration regime in which combustion is complete and the near-lean-limit regime in which buoyant flame propagation and extinction are important. Empirical representations of burning velocities and flame geometries are utilized in both regimes. Transient overpressures calculated with these models are compared to recent data obtained in several test programs. Although reasonable agreement is obtained in many cases, the comparisons suggest that the model could be improved by accounting for self-induced flame turbulence and for radiative heat losses before the flame reaches the vessel wall

1982-10-03

58

PDF modeling of turbulence-radiation interactions  

Energy Technology Data Exchange (ETDEWEB)

The interactions between turbulence and radiation, although acknowledged and qualitatively understood over the last several decades, are extremely difficult to model. Traditional Eulerian turbulence models are incapable of addressing the closure problem for any realistic reactive flow situation, because of the large number of unknown turbulent moments that need to be modeled. A novel approach, based on the velocity-composition joint probability density function (PDF) method, is presented. This approach is Lagrangian in nature and provides an elegant and feasible alternative to turbulence closure. A mixed Monte Carlo/finite-volume technique is used to simulate a bluff-body-stabilized methane-air diffusion flame in a two-dimensional planar recirculating combustor, and enables treatment of turbulence in recirculating flows, finite-rate chemistry, and multiple-band radiation calculations within the CPU limitations of a standard single-processor workstation. Results demonstrate the role of radiation and turbulence-radiation interactions in altering the overall flame structure, the wall heat loads, and the overall heat emission by the flame at various Reynolds numbers and equivalence ratios.

Mazumder, S.; Modest, M.F.

1997-07-01

59

Effect of ionizing radiation on moist air systems  

International Nuclear Information System (INIS)

The radiation chemistry of nitrogen/oxygen/water systems is reviewed. General radiolytic effects in dry nitrogen/oxygen systems are relatively well characterized. Irradiation results in the formation of steady state concentrations of ozone, nitrous oxide and nitrogen dioxide. In closed systems, the concentration observed depends on the total dose, temperature and initial gas composition. Only three studies have been published that focus on the radiation chemistry of nitrogen/oxygen/water homogeneous gas systems. Mixed phase work that is relevant to the gaseous system is also summarized. The presence of water vapor results in the formation of nitric acid and significantly changes the chemistry observed in dry air systems. Mechanistic evidence from the studies reviewed are summarized and discussed in relation to characterizing the gas phase during the containment period of a repository in tuff

1987-11-30

60

Air  

…air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality management * Air Quality Modelling and Assessment Unit.  See links below for additional information. Mitigation… Related Searches: position statements

 
 
 
 
61

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 reducti...

Kloster, S.; Dentener, F.; Feichter, J.; Raes, F.; Aardenne, J.; Roeckner, E.; Lohmann, U.; Stier, P.; Swart, R. J.

2008-01-01

62

Urban Air Quality Assessment Model UAQAM  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Urban Air Quality Assessment Model (UAQAM) calculates the city concentration caused by city emissions themselves, the so-called city background concentration. Three versions of the model for describing the dispersion were studied: Box, Gifford Hanna (GH) and a combined form of these two (the Box-GH model). Regional background emissions contributing to the city background concentration were accounted for using measurements and TREND model calculations. The UAQAM model ver...

Waj, Pul; Edg, Zantvoort; Faam, Leeuw; Rjcf, Sluyter

2007-01-01

63

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

Supawan TIRAWANICHAKUL

2008-01-01

64

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

65

Modeling benzene NAPL removal during air sparging  

Energy Technology Data Exchange (ETDEWEB)

Air sparging is a commonly used enhanced remedial tool for in-situ aquifer remediation. In an attempt to test assumptions commonly made in air sparging models, a lab-scale reactor with two isolated and controlled vertical channels of air through saturated porous media was used to study air sparging of a benzene NAPL under different airflow rates in the absence of retardation and groundwater flow. A simple dissolution-diffusion-volatilization (DDV) model was constructed to compare experimental results with the modeled results. Increasing the airflow rate from 45 mL/min to 125 mL/min had little to no effect on mass removal or the estimated volatilization or dissolution mass transfer rate constants when using a simple dissolution-diffusion-volatilization (DDV) model. This result was similar to that of many other researchers. The DDV model was, however unable to predict increased concentrations above the source zone in the aqueous phase. Furthermore, it produced predictions of a longer lag time for volatilization than experimentally determined. These results suggest that advection and dispersion may not only be solely caused by regional groundwater flow, but also momentum transfer from the advecting air.

Rogers, S.W.; Ong, S.K.

1999-07-01

66

Optimization of air gamma spectrometry for radiation monitoring and location of radiation sources  

International Nuclear Information System (INIS)

Currently in the Czech Republic for air gamma spectrometry and radiation monitoring systems are used two (Army of the Czech Republic, SURO) of aerial gamma spectrometry type of IRIS (Pico Envirotec Inc.) with detector NaI(Tl) with a capacity of 16 litres. The work presents results of experiments monitoring of natural radionuclides (U-238, Th-232 and K-40), monitoring the radionuclide Cs-137 in the environment after the Chernobyl accident and the results of testing with closed-type sources of radiation of unshielded radionuclides Cs-137, Eu-152 and Co-60, with activities of tens of MBq to GBq.

2011-11-01

67

Optimization Framework for Air Force Logistics Models.  

Science.gov (United States)

The goal of this project was to create a new framework of models and algorithms to address grand challenges in the US Air Force logistics. We have developed new models, algorithms and performance analysis techniques that address major current and future l...

R. Levi T. Magnanti

2011-01-01

68

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

69

Stochastic microenvironment models for air pollution exposure  

Energy Technology Data Exchange (ETDEWEB)

Exposure assessment is a crucial link in air pollution risk assessment and management. With the recent advances in instrumentation, it has become possible to measure air pollution exposures in the vicinity of the individual human subjects, using either personal monitoring or microenvironment monitoring. For many important pollutants such as CO, NO2, and VOC, the air pollution exposure depends crucially on the location and activity of the individual: indoor versus outdoor, smoking versus not smoking, etc. The stochastic microenvironment models were developed to relate air pollution exposure to the location and activity. We review the two major existing models, the Cartesianization method and SHAPE, and compare their assumptions and implications. We also propose a new model, the variance components model, which includes both Cartesianization and SHAPE as special cases. The variance components model considers both long-term average concentrations and short-term fluctuations. The Cartesianization focuses on long-term averages, while SHAPE focuses on short-term fluctuations. We propose to choose among the three models by examining the variance function which relates variability to averaging time. The theory is applied to the data collected from U.S. EPA's Washington CO Study, with the variance function estimated using Carroll and Ruppert's transform-both-sides regression model and Duan's smearing estimate. For the microenvironment in transit, both long-term averages and short-term fluctuations are important.

Duan, N. (RAND Corporation, Santa Monica, CA (United States))

1991-04-01

70

Bayesian model comparison of solar radiation models  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we propose a new statistical method: the Bayesian Model Comparison (BMC) method for selecting an adequate hourly diffuse fraction correlation. Six models are investigated and compared according to the BMC method. The selection of the best model is based on a Bayesian criterion called the Deviance Information Criterion (DIC). In this article, we demonstrate the usefulness of the DIC criterion in the model selection process and we issue a caution regarding the selection of a model with standard statistical methods. The aim of this paper is also to introduce the DIC to the solar radiation modeling community. (orig.)

Lauret, Philippe; Riviere, Carine [Lab. de Physique du Batiment et des Systemes, Saint-Denis (France)

2008-07-01

71

Quantitative evaluating the energy field of pulsed x radiation backscattered in air  

International Nuclear Information System (INIS)

Air background (fraction of radiation, backscattered in air) taken into account when conducting measurements using the devices with operating principle based on the dependence of backscattered ?-quanta flux density reo.istered in the given time interval (strobe) on the measured parameters is evaluated. It is shown that the energy of ?-quanta backscattered in an air layer energy of pulsed x radiation background in a strobe is defined not only by initial radiation energy and collimation angle but by the strobe location on time axis in relation to the radiated pulse as well i.e. by air layer location in space

1985-10-01

72

Dynamical models of radiative shocks  

International Nuclear Information System (INIS)

The spectral characteristics of steady and unsteady radiative shock models have been investigated in the context of Supernova Remnants (SNRs). By means of detailed, multi-level radiative transfer calculations, emission and absorption line profiles for selected shock models have been generated. Geometrical effects are simulated by forming the plane models into a thin spherical shell, which is then observed along different lines-of-sight. It is shown that the nature of unsteady shocks can best be studied through observations of absorption and emission line profiles along lines-of-sight near to the centre of the SNR. Also, it is shown why emission maps in the light of optically thick transitions should not exhibit the bright filaments associated with optically thin lines. (author)

1987-08-15

73

CCMS air pollution model intercomparison study  

Energy Technology Data Exchange (ETDEWEB)

Four air pollution transport models were tested and compared in an area of approx. 400 x 400 km/sup 2/. Three models were Eulerian grid models, the fourth a Lagrangian trajectory model. The data base (emissions and meteorological observations) were essentially the same for all models. Differences in model output could only be a result of the different (numerical) structure of the models and of the differences in processing of the meteorological data. It turned out that the latter was the major source of differences in model results. Generally there was a satisfactory correlation between model results and observed concentrations. Mainly due to the negligence of transport of pollutants into the modelling region, predicted concentrations were considerably lower than the observed.

van Dop, H.

1986-01-01

74

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

75

Using Multicommodity Network Models for the Air Force Logistics Command.  

Science.gov (United States)

This paper reports on a successful application of mathematical programming for the Air Force Logistics Command. It presents a pair of multicommodity network flow models which represent the air freight network utilized by the Air Force to support sixty bas...

A. I. Ali R. V. Helgason J. L. Kennington

1980-01-01

76

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

77

Model Identification of a Micro Air Vehicle  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper is focused on the model identification of a Micro Air Vehicle (MAV) in straight steady flight condition. The identification is based on input-output data collected from flight tests using both frequency and time domain techniques. The vehicle is an in-house 40 cm wingspan airplane. Because of the complex coupled, multivariable and nonlinear dynamics of the aircraft, linear SISO structures for both the lateral and longitudinal models around a reference state were derived. The aim of...

Nin?o Castan?eda, Jorge; Mitrache, Flavius; Cosyn, Peter; Keyser, Robain

2007-01-01

78

Stochastic Modeling of Indoor Air Temperature  

Science.gov (United States)

Temperature is one of the main parameters describing thermal comfort and indoor air quality. In this paper we propose an approach, based on a modification of the continuous time random walk, to model the indoor air temperature. We perform a statistical analysis of the recorded time series, that allows us to point out the main statistical properties of the recorded variable. The obtained conclusions about the nature of the process lead to a continuous time random walk, that in contrast to the classical approach, models time dependence of the jumps distribution. Moreover, we show that the waiting times can be modeled by a tempered stable distribution, which yields a subdiffusive behavior in short times and diffusive behavior in longer times. Finally, by conducting a simulation study we illustrate possible applications of the presented approach in the thermal comfort monitoring and forecasting.

Janczura, Joanna; Maciejewska, Monika; Szczurek, Andrzej; Wy?oma?ska, Agnieszka

2013-09-01

79

A comparison of collimated and free air radiation sources in the calibration of radiation protection instruments  

International Nuclear Information System (INIS)

A report is given of the differences in response of a range of radiation protection instruments, including ionisation chambers, Geiger Muller and scintillation types, when calibrated using either a well collimated "2"2"6Ra source or a free air "2"2"6Ra source in similar calibration rooms. The results show that with the collimated source there is generally a lack of secondary equilibrium and that with the panoramic source there is an excess of scattered electrons. The implications of these results are discussed with reference to practical monitoring and calibration. (author)

1982-01-01

80

Radiative transfer in LTE air plasmas for temperatures up to 15,000 K  

Energy Technology Data Exchange (ETDEWEB)

Radiative transfer in local thermodynamic and chemical equilibrium N{sub 2}-O{sub 2} plasmas is analyzed in this study using a line-by-line approach. The contributions of line absorption by atoms, ions and of continuous absorption by atoms, ions and molecules to the absorption coefficient of heated air are calculated. These data combined to our previous work on the contribution of molecular electronic systems to heated air radiation (J. Quant. Spectrosc. Radiat. Transfer 72 (2002) 503) lead to a reliable and exhaustive spectroscopic data base for radiative transfer in air plasmas and for temperatures up to 15,000 K. Line-by-line radiative transfer calculations are carried out for a simple planar geometry with prescribed temperature profiles. The spectral distribution of radiative fluxes and volumetric powers is analyzed and the relative contributions of continuum and line radiation are discussed.

Chauveau, Sophie; Deron, Christine; Perrin, M.-Y.; Riviere, Philippe; Soufiani, Anouar

2003-03-01

 
 
 
 
81

Radiative transfer in LTE air plasmas for temperatures up to 15,000 K  

International Nuclear Information System (INIS)

Radiative transfer in local thermodynamic and chemical equilibrium N2-O2 plasmas is analyzed in this study using a line-by-line approach. The contributions of line absorption by atoms, ions and of continuous absorption by atoms, ions and molecules to the absorption coefficient of heated air are calculated. These data combined to our previous work on the contribution of molecular electronic systems to heated air radiation (J. Quant. Spectrosc. Radiat. Transfer 72 (2002) 503) lead to a reliable and exhaustive spectroscopic data base for radiative transfer in air plasmas and for temperatures up to 15,000 K. Line-by-line radiative transfer calculations are carried out for a simple planar geometry with prescribed temperature profiles. The spectral distribution of radiative fluxes and volumetric powers is analyzed and the relative contributions of continuum and line radiation are discussed

2003-03-01

82

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 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

83

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

1999-01-01

84

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

85

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

86

AIR INGRESS ANALYSIS: COMPUTATIONAL FLUID DYNAMIC MODELS  

International Nuclear Information System (INIS)

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.

2010-08-08

87

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

88

The Martian Energetic Radiation Environment Models  

Science.gov (United States)

The Martian Energetic Radiation Environment Models The high energy ionising radiation environment in the solar system consists of three main sources: the planetary radiation belts, galactic cosmic rays and solar energetic particles. Future Mars missions potentially carry significant risk from long-term exposure to ionising radiation. The Martian Energetic Radiation Environment Models, MEREM, were developed in order to simulate the Martian radiation environment. The models, eMEREM and dMEREM, respec-tively engineering and detailed Martian Energetic Radiation Environment Models, are based on the Geant4 and FLUKA radiation transport programs, combined with Mars Climate Database model for the atmosphere. MOLA (Mars Orbiter Laser Altimeter) data and gamma-ray spec-trometer data have been used to define surface topology and surface composition (including presence of water), respectively. Although the models are capable of operating on standalone mode, a SPENVIS (space envi-ronment information system) compatible, web-based user interface was developed to provide an integrated environment to predict the Martian radiation and greatly simplify the operation of the software by non-experts and by future mission developers. Results of the Mars Energetic Radiation Environment Models concerning the estimate of effec-tive doses and ambient dose equivalents for potential Martian landing sites having regard to the combined incidence, under solar minimum and solar maximum conditions, of flare related particle radiation and background galactic cosmic ray radiation are presented.

Gonçalves, Patrícia; Keating, Ana; Truscott, Pete; Lei, Fan; Desorgher, Laurent; Heynderickx, Daniel; Crosby, Norma Bock; Nieminen, Petteri; Santin, Giovanni

89

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

90

Simple model for radiation damping  

Energy Technology Data Exchange (ETDEWEB)

It is pointed out that the discovery of the binary pulsar PSR 1913+16 has led to renewed interest in approximation methods for the construction and solution of equations of motion in general relativity. The technique of matched asymptotic expansions discussed by Fraenkel (1969) appears to be the most useful method for treating the problem. There are, however, difficulties in transferring this technique to general relativity. The equations are hyperbolic, for which the technique has not been tested. Another problem is related to the difficulty of doing experiments in which the parameters can be controlled. The present investigation is concerned with the application of matched asymptotic expansions to determine the radiation damping of a particularly simple model system. The model consists of a harmonic oscillator described by an amplitude y(t) coupled to a spherically symmetric zero rest mass scalar field.

Stewart, J.M.

1983-05-01

91

An automobile air conditioner design model  

Energy Technology Data Exchange (ETDEWEB)

A computer program has been developed to predict the steady-state performance of vapor compression automobile air conditioners and heat pumps. The code is based on the residential heat pump model developed at the Oak Ridge National Laboratory (ORNL). Most calculations are based on fundamental physical principles, in conjunction with generalized correlations available in the research literature. Automobile air conditioning components that can be specified as input to the program include open and hermetic compressors; finned tube condensers; finned tube and plate-fin style evaporators; thermostatic expansion valves (TXV), capillary tube, and short tube expansion devices; refrigerant mass; and evaporator pressure regulator and all interconnecting tubing. Pressure drop, heat transfer rates, and latent capacity ratio for the new plate-fin evaporator submodel are shown to agree well with laboratory data. The program can be used with a variety of refrigerants, including R-134a.

Kyle, D.M.; Mei, V.C.; Chen, F.C.

1992-12-01

92

Model Test of Air-Exchange Efficiency,  

Science.gov (United States)

The mixing air flow pattern was studied. Three air flows were tested using the tracer gas technique and decay method. The indices of air exchange efficiency were calculated, namely: overall air exchange efficiency and room air mean age for the whole room;...

K. Klobut

1987-01-01

93

Air Dispersion Modeling for Building 3026C/D Demolition  

Energy Technology Data Exchange (ETDEWEB)

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 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.7 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.7 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.

Ward, Richard C [ORNL; Sjoreen, Andrea L [ORNL; Eckerman, Keith F [ORNL

2010-06-01

94

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 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.

2010-01-01

95

Air Pollution: Assessment Methodology and Modeling. Bibliography of Grey Literature on Air Quality Modeling (GAUSSian Plume Models).  

Science.gov (United States)

From the results of the NATO/CCMS Pilot Study Air Pollution, fifteen recommendations have been derived, one of which deals with air quality modeling. Since the publication of this recommendation, a world-wide cooperation in the field of modeling activitie...

1977-01-01

96

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

97

77 FR 4808 - Conference on Air Quality Modeling  

Science.gov (United States)

...quality models in Appendix W including the CALPUFF modeling system, AERMOD modeling system...near-field regulatory applications, and the CALPUFF modeling system, the EPA's preferred...preferred air quality models (AERMOD and CALPUFF) status and updates; D. Review of...

2012-01-31

98

Models for human exposure to air pollution  

International Nuclear Information System (INIS)

Four models for human exposure to air pollution are discussed and compared. Simple microenvironment monitoring measures pollutant concentrations at fixed locations, regarded as proxies for similar locations or microenvironments. This model does not require pollutant measurements on the individual level, therefore is easy to implement. However, the model can be used only to estimate the average exposure in a population and does not provide any estimate of the variability and distribution of individual exposures. Replicated microenvironment monitoring provides some estimates of the variability and distribution. However, because of the possible discrepancy between the microenvironment concentration distribution and the individual concentration distribution, some adjustment might be necessary. Integrated personal monitoring allows direct estimation of the average exposure as well as the variability and distribution of individual exposures. Coupled with the appropriate time budget data, a regression analysis can be applied to estimate the contribution from each microenvironment type

1982-01-01

99

Models for human exposure to air pollution  

Energy Technology Data Exchange (ETDEWEB)

Four models for human exposure to air pollution are discussed and compared. Simple microenvironment monitoring measures pollutant concentrations at fixed locations, regarded as proxies for similar locations or microenvironments. This model does not require pollutant measurements on the individual level, therefore is easy to implement. However, the model can be used only to estimate the average exposure in a population and does not provide any estimate of the variability and distribution of individual exposures. Replicated microenvironment monitoring provides some estimates of the variability and distribution. However, because of the possible discrepancy between the microenvironment concentration distribution and the individual concentration distribution, some adjustment might be necessary. Integrated personal monitoring allows direct estimation of the average exposure as well as the variability and distribution of individual exposures. Coupled with the appropriate time budget data, a regression analysis can be applied to estimate the contribution from each microenvironment type.

Duan, N.

1982-07-01

100

Recent advances in CAMx air quality modelling  

Energy Technology Data Exchange (ETDEWEB)

The comprehensive air-quality model with extensions (CAMx) is a publicly available photochemical grid model that was developed and coded during the late 1990s using modern and modular coding practices. The modern framework makes CAMx ideally suited for expansion to treat other air quality issues, and as a host model for advanced sensitivity and mass balance algorithms. In this paper we discuss recent advances in the development of CAMx including the implementation of several advanced ''probing tools'' as follows: Ozone source apportionment technology (OSAT) and its derivatives to identify the contributions of source regions and emission categories to ozone. Decoupled direct method (DDM) sensitivity analysis approach to estimate the sensitivity of ozone and other pollution concentrations to key input parameters including emissions, initial concentrations, and boundary conditions. Process analysis (PA) to explain the processes that lead to and govern ozone formation using the integrated process rate (IPR) and integrated reaction rate (IRR) and chemical process analysis (CPA) methods. (orig.)

Morris, R.E.; Yarwood, G. [ENVIRON International Corp., Novato, CA (United States); Wagner, A. [ENVIRON-UK, Longvilliers (France)

2002-07-01

 
 
 
 
101

A Numerical Model for Multigroup Radiation Hydrodynamics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 gr...

Vaytet, N.; Audit, E.; Dubroca, B.; Gonza?lez, M.

2012-01-01

102

Age of air and air exchange efficiency in idealized city models  

Energy Technology Data Exchange (ETDEWEB)

Wind can provide relevantly clean external (rural) air into urban street network, i.e. city ventilation. The local mean age of air denotes the time it takes for the external air to reach a location after entering the urban canopy layer. The air exchange efficiency denotes the efficiency of flushing the street network with external air. However, difficulties exist in calculating the local mean age of air in a city due to open boundaries. The traditional experimental homogeneous emission method is adapted here in a CFD method to predict the urban local age of air and analyze the air exchange efficiency for city ventilation. Three simple city models are considered, including a round city model, a square city model and a long rectangular city with one main street parallel to the approaching wind or with two crossing streets. The difference in the city shape results in significant difference in the local mean age of air. In the round city of one narrow street, two inflows through street openings converge close to the city centre and exits through the street roof, so the air close to the city centre is relatively old and the air exchange efficiency is low (30%). For a round city with two crossing streets, a slightly non-parallel wind to the main street generates younger air and the higher air exchange efficiency in the city. (author)

Hang, Jian; Li, Yuguo [Department of Mechanical Engineering, The University of Hong Kong, Haking Wong Building, Pokfulam Road, Hong Kong SAR (China); Sandberg, Mats [KTH Research School, Laboratory of Ventilation and Air Quality, University of Gaevle, 801 76 Gaevle (Sweden)

2009-08-15

103

Air  

…information. Mitigation opportunities * Policy wording * Refined alternatives * Pollution prevention guidance notes  * Cumulative Effects Assessment (CEA) * Emissions trading. See links below for additional information. * Air Quality Modelling and Assessment Unit (AQMAU) AQMAU is the Environment Agency's… Related Searches: position statements

104

Air  

…information. Mitigation opportunities * Policy wording * Refined alternatives * Pollution prevention guidance notes  * Cumulative Effects Assessment (CEA) * Emissions trading. See links below for additional information. * Air Quality Modelling and Assessment Unit (AQMAU) AQMAU is the Environment Agency's…

105

A temperature-based model for estimating monthly average daily global solar radiation in China.  

Science.gov (United States)

Since air temperature records are readily available around the world, the models based on air temperature for estimating solar radiation have been widely accepted. In this paper, a new model based on Hargreaves and Samani (HS) method for estimating monthly average daily global solar radiation is proposed. With statistical error tests, the performance of the new model is validated by comparing with the HS model and its two modifications (Samani model and Chen model) against the measured data at 65 meteorological stations in China. Results show that the new model is more accurate and robust than the HS, Samani, and Chen models in all climatic regions, especially in the humid regions. Hence, the new model can be recommended for estimating solar radiation in areas where only air temperature data are available in China. PMID:24605046

Li, Huashan; Cao, Fei; Wang, Xianlong; Ma, Weibin

2014-01-01

106

AIR QUALITY MODELING FOR THE TWENTY-FIRST CENTURY  

Science.gov (United States)

This presentation describes recent and evolving advances in the science of numerical air quality simulation modeling. Emphasis is placed on new developments in particulate matter modeling and atmospheric chemistry, diagnostic modeling tools, and integrated modeling systems. New...

107

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

108

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

109

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

2013-08-12

110

Air pollutants and energy pathways: Extending models for abatement strategies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 p...

Syri, Sanna

2001-01-01

111

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

1979-10-01

112

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

1996-01-01

113

Radiation checkpoints in model systems  

Energy Technology Data Exchange (ETDEWEB)

The response to DNA damaging agents includes a delay to progression through the cell cycle. Irradiation of premitotic cells causes a delay to mitosis and irradiation of G{sub 1} and S phase cells causes a delay to DNA synthesis. These delays have become known as checkpoints. The mechanisms that mediate the mitotic (or G{sub 2}) checkpoint delay have recently come under study in yeast model systems. Work in the eukaryotic organisms S. cerevisiae and S. pombe has identified at least seven proteins controlling the interactions between DNA damage and cell cycle progression. Genetic analysis of this checkpoint pathway has identified substantial overlap with the feedback controls that co-ordinate progression through the cell cycle. Molecular analysis has revealed structural conservation between these highly diverged yeasts, which suggests that similar proteins may act in related pathways in mammalian cells. In addition, the rad24 and rad25 genes of S. pombe (which are involved in the radiation checkpoint) encode functionally overlapping essential proteins that are highly conserved in mammalian cells. Studies of checkpoints in the yeasts may therefore help to define the signal pathways that control cell cycle delay in mammalian cells following irradiation, some of which have been proposed to be deficient in A-T cells. (author).

Carr, A.M. [Sussex Univ., Brighton (United Kingdom). MRC Cell Mutation Unit

1994-12-01

114

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

115

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

116

Models for human exposure to air pollution  

Energy Technology Data Exchange (ETDEWEB)

Four models for human exposure to air pollution are discussed and compared. The simple microenvironment monitoring model measures pollutant concentrations at fixed location, regarded as proxies for similar locations or microenvironments. Since this model does not require pollutant measurements on the individual level, it is easy to implement. However, the model can only be used to estimate the average exposure in a population, and it does not provide any estimate of the variability and distribution of individual exposures. The replicated microenvironment monitoring model provides some estimates of the variability and distribution. However, because of the possible discrepancy between the microenvironment concentration distribution and the individual concentration distribution, some adjustment might be necessary. Integrated personal monitoring allows direct estimation of the average exposure as well as the variability and distribution of individual exposures. Coupled with the appropriate time budget data, a regression analysis can be applied to estimate the contribution from each microenvironment type. However, possible collinearity problems might result in low precision in those estimates. Moreover, it might be difficult to adjust for a possible Hawthorne effect. Continuous personal monitoring has the advantage of recording exposure in each microenvironment type separately, allowing direct estimation of the average exposure as well as the variability and distribution of exposures in each microenvironment type. Moreover, it can also be conducted in conjunction with a two-stage sampling scheme, using information from a large data base on activity patterns, thereby making more efficient use of the monitoring data. It is also easier to adjust for a possible Hawthorn effect in this design.

Duan, N.

1982-01-01

117

A simple model for cloud radiative forcing  

Directory of Open Access Journals (Sweden)

Full Text Available 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 the example of tropical cirrus clouds. We conclude that possible applications for the model include the convenient estimate of cloud radiative forcing for a wide range of conditions, the evaluation of the sensitivity to changes in environmental conditions, and as a tool in education. An online version of the model is available at http://www.iac.ethz.ch/url/crf.

T. Corti

2009-08-01

118

NCAQ panel examines uses and limitations of air quality models  

International Nuclear Information System (INIS)

The results of a 22-member expert panel on dispersion modeling, which was convented by the National Commission on Air Quality in 1979, are reviewed. The panel affirmed the validity of using models in support of air quality regulations. It also recognized the need to convey some of the uncertainty in modeling and recommended technical details for the commission to consider

1981-01-01

119

?????? ?????????????? ?????????? ??????????? ?? ??????? ??????-????????? ??? ?????????????? ??????????? ???? HUMAN PERFORMANCE MODELS AND HUMAN ERRORS IN AIR TRAFFIC MANAGEMENT ?????? ?????????????????? ??????????? ??????????? ? ?????? ????????-????????? ??? ???????????? ?????????? ????????  

Directory of Open Access Journals (Sweden)

Full Text Available  ?????????? ?????? ?????????????? ?????????? ??????????? ? ???????? ?????? ?? ???????????? ??????? ? ???? ??????????? ?????????? ?????????? ???????????. The models of air traffic controller performance and principles of estimation and prevention of errors in the course of controller professional activity are considered. ??????????? ?????? ?????????????????? ??????????? ??????????? ? ???????? ?????? ? ?????????????? ?????? ? ???? ???????????????? ???????????? ??????????? ???????????.

Yuriy V. Chynchenko

2008-02-01

120

Modeling activities in air traffic control systems: antecedents and consequences of a mid-air collision.  

Science.gov (United States)

In this article we present a model of some functions and activities of the Brazilian Air traffic Control System (ATS) in the period in which occurred a mid-air collision between flight GLO1907, a commercial aircraft Boeing 737-800, and flight N600XL, an executive jet EMBRAER E-145, to investigate key resilience characteristics of the ATM. Modeling in some detail activities during the collision and related them to overall behavior and antecedents that stress the organization uncover some drift into failure mechanisms that erode safety defenses provided by the Air Navigation Service Provider (ANSP), enabling a mid-air collision to be happen. PMID:22316728

de Carvalho, Paulo Victor R; Ferreira, Bemildo

2012-01-01

 
 
 
 
121

Dark Radiation Confronting LHC in Z' Models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 E6 Z' models to account for the present evidence of dark radiation with the al...

Solaguren-beascoa, A.; Gonzalez-garcia, M. C.

2012-01-01

122

Radiation force model for CESAR experiment.  

Science.gov (United States)

The author presents a radiation force model devised for interpretation of the data from the microaccelerometric experiment "MACEK" on board of the proposed "CESAR" satellite. Starting with a brief overview of the mathematical technique he concentrates on explaining the theoretical concepts. He focuses on the external radiation effects - direct solar radiation pressure, pressure of the sunlight reflected on the Earth surface and pressure of the IR emission of the Earth. Numerical simulations of the MACEK device measurement are discussed and analyzed.

Vokrouhlický, D.

123

Application of Improved Radiation Modeling to General Circulation Models  

Energy Technology Data Exchange (ETDEWEB)

This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

Michael J Iacono

2011-04-07

124

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

Energy Technology Data Exchange (ETDEWEB)

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 (r{sup 2} = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r{sup 2} = 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.

Fahimian, Benjamin; Türkcan, Silvan; Kapp, Daniel S.; Pratx, Guillem, E-mail: pratx@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 (United States); Ceballos, Andrew [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

2014-01-15

125

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)

2009-03-01

126

The dynamic radiation environment assimilation model (DREAM)  

Energy Technology Data Exchange (ETDEWEB)

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.

Reeves, Geoffrey D [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Tokar, Robert L [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory; Friedel, Reiner H [Los Alamos National Laboratory

2010-01-01

127

Modelled air pollution levels versus EC air quality legislation - results from high resolution simulation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An appropriate method for evaluating the air quality of a certain area is to contrast the actual air pollution levels to the critical ones, prescribed in the legislative standards. The application of numerical simulation models for assessing the real air quality status is allowed by the legislation of the European Community (EC). This approach is preferable, especially when the area of interest is relatively big and/or the network of measurement stations is sparse, and the available observati...

Chervenkov, Hristo

2013-01-01

128

Validation of spectral gas radiation models under oxyfuel conditions  

Energy Technology Data Exchange (ETDEWEB)

Combustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition than combustion with air. Standard computational-fluid-dynamics (CFD) spectral gas radiation models for air combustion are therefore out of their validity range in oxyfuel combustion. This thesis provides a common spectral basis for the validation of new spectral models. A literature review about fundamental gas radiation theory, spectral modeling and experimental methods provides the reader with a basic understanding of the topic. In the first results section, this thesis validates detailed spectral models with high resolution spectral measurements in a gas cell with the aim of recommending one model as the best benchmark model. In the second results section, spectral measurements from a turbulent natural gas flame - as an example for a technical combustion process - are compared to simulated spectra based on measured gas atmospheres. The third results section compares simplified spectral models to the benchmark model recommended in the first results section and gives a ranking of the proposed models based on their accuracy. A concluding section gives recommendations for the selection and further development of simplified spectral radiation models. Gas cell transmissivity spectra in the spectral range of 2.4 - 5.4 {mu}m of water vapor and carbon dioxide in the temperature range from 727 C to 1500 C and at different concentrations were compared in the first results section at a nominal resolution of 32 cm{sup -1} to line-by-line models from different databases, two statistical-narrow-band models and the exponential-wide-band model. The two statistical-narrow-band models EM2C and RADCAL showed good agreement with a maximal band transmissivity deviation of 3 %. The exponential-wide-band model showed a deviation of 6 %. The new line-by-line database HITEMP2010 had the lowest band transmissivity deviation of 2.2% and was therefore recommended as a reference model for the validation of simplified CFD models. In the second results section, spectral measurements (2.4 - 5.4 {mu}m) of a 70 kW turbulent natural gas ame in air blown combustion and in wet and dry oxyfuel combustion were compared with simulated spectra based on measured gas atmospheres. The line-by-line database HITEMP2010 and the two statistical-narrow-band models EM2C and RADCAL were used for the numerical simulation. The measured spectra showed large fluctuations due to turbulence. The averaged experimental intensity was found to be up to 75% higher than the simulated intensity, thus demonstrating the importance of the effect of turbulence-radiation-interaction in combustion simulations. Finally, total emissivities were calculated with the most common spectral models and compared with benchmark calculations by the detailed spectral line-by-line model HITEMP2010. The models were compared at path lengths ranging from 0.001m to 100m and at temperatures from 800 C to 1800 C for atmospheres of pure gases and of various combustion processes (air blown and oxyfuel combustion with wet and dry recirculation) as well as with different fuels (natural gas, brown coal and anthracite). The statistical-narrow-band models RADCAL and EM2C, the exponential-wide-band model and the statistical-line-width model were chosen as models, which are valid for oxyfuel combustion without modifications. A number of weighted-sum-of-grey-gases models from different authors were chosen as computationally efficient models especially developed for oxyfuel combustion. The statistical-narrow-band model EM2C had the highest accuracy with maximum deviations of up to 12%. The weighted-sum-of-grey-gases model from Johansson et al. [64] proved to be the most valid and versatile model for computationally efficient simulations of spectral gas properties with an overall accuracy of 21% or better.

Becher, Johann Valentin

2013-05-15

129

A diffraction radiation model for energy losses  

International Nuclear Information System (INIS)

The electromagnetic interaction of a bunch of particles with the surrounding equipment is cause of a radiation process leading to energy losses. The radiation may substantially reduce the energy gain of an accellerating structure therefore more power has to be supplied to the beam. Radiation laws derived by experimental observations and by some theoretical models predict an unrealistic infinite energy loss for infinitely short bunches. An analytical approach developed for an ideal simple structure which allows for deriving a radiation law for any bunch length and particle energy is here presented

1987-07-04

130

Model-based estimation of changes in air temperature seasonality  

Science.gov (United States)

Seasonality is a ubiquitous feature in climate time series. Climate change is expected to involve not only changes in the mean of climate parameters but also changes in the characteristics of the corresponding seasonal cycle. Therefore the identification and quantification of changes in seasonality is a highly relevant topic in climate analysis, particularly in a global warming context. However, the analysis of seasonality is far from a trivial task. A key challenge is the discrimination between long-term changes in the mean and long-term changes in the seasonal pattern itself, which requires the use of appropriate statistical approaches in order to be able to distinguish between overall trends in the mean and trends in the seasons. Model based approaches are particularly suitable for the analysis of seasonality, enabling to assess uncertainties in the amplitude and phase of seasonal patterns within a well defined statistical framework. This work addresses the changes in the seasonality of air temperature over the 20th century. The analysed data are global air temperature values close to surface (2m above ground) and mid-troposphere (500 hPa geopotential height) from the recently developed 20th century reanalysis. This new 3-D Reanalysis dataset is available since 1891, considerably extending all other Reanalyses currently in use (e.g. NCAR, ECWMF), and was obtained with the Ensemble Filter (Compo et al., 2006) by assimilation of pressure observations into a state-of-the-art atmospheric general circulation model that includes the radiative effects of historical time-varying CO2 concentrations, volcanic aerosol emissions and solar output variations. A modeling approach based on autoregression (Barbosa et al, 2008; Barbosa, 2009) is applied within a Bayesian framework for the estimation of a time varying seasonal pattern and further quantification of changes in the amplitude and phase of air temperature over the 20th century. Barbosa, SM, Silva, ME, Fernandes, MJ, 2008. Changing seasonality in North Atlantic coastal sea level from the analysis of long tide gauge records. Tellus, 60A, 165-177. Barbosa, SM, 2009. Changing seasonality in Europe's air temperature. European Physical Journal - Special Topics, 174, 81-89. Compo,G.P., J.S. Whitaker, and P.D. Sardeshmukh, 2006: Feasibility of a 100 year reanalysis using only surface pressure data. Bull. Amer. Met. Soc., 87, 175-190.

Barbosa, Susana; Trigo, Ricardo

2010-05-01

131

Validation of a 3-D hemispheric nested air pollution model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Several air pollution transport models have been developed at the National Environmental Research Institute in Denmark over the last decade (DREAM, DEHM, ACDEP and DEOM). A new 3-D nested Eulerian transport-chemistry model: REGIonal high resolutioN Air pollution model (REGINA) is based on modules and parameterisations from these models as well as new methods.

The model covers the majority of the Northern Hemisphere with currently one nest implemented. The horizontal...

Frohn, L. M.; Christensen, J. H.; Brandt, J.; Geels, C.; Hansen, K. M.

2003-01-01

132

Solar Radiation: Absence of Air Pollution Trends at Mauna Loa.  

Science.gov (United States)

Measurements of solar radiation made at Mauna Loa, Hawaii over a period of 13 years give no evidence that human activities affect atmospheric turbidity on a global scale. Short-term fluctuations in insolation appear to be associated with naturally produce...

H. T. Ellis R. F. Pueschel

1971-01-01

133

A model of interband radiative transitions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We consider a simple model which is a caricature of a crystal interacting with a radiation field. The model has two bands of continuous spectrum and the particle can pass from the upper one to the lower by radiating a photon, the coupling between the excited and deexcited states being of a Friedrichs type. Under suitable regularity and analyticity assumptions we find the continued resolvent and show that for weak enough coupling it has a curve-type singularity in the lower h...

Dittrich, J.; Exner, P.; Hirokawa, M.

2000-01-01

134

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

135

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 n [...] ove 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. Abstract in english 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; Valdiney J. da, Silva; José, Alves Júnior; Hudson de P., Carvalho.

136

A review of air exchange rate models for air pollution exposure assessments.  

Science.gov (United States)

A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings where people spend their time. The AER, which is the rate of exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pollutants and for removal of indoor-emitted air pollutants. This paper presents an overview and critical analysis of the scientific literature on empirical and physically based AER models for residential and commercial buildings; the models highlighted here are feasible for exposure assessments as extensive inputs are not required. Models are included for the three types of airflows that can occur across building envelopes: leakage, natural ventilation, and mechanical ventilation. Guidance is provided to select the preferable AER model based on available data, desired temporal resolution, types of airflows, and types of buildings included in the exposure assessment. For exposure assessments with some limited building leakage or AER measurements, strategies are described to reduce AER model uncertainty. This review will facilitate the selection of AER models in support of air pollution exposure assessments.Journal of Exposure Science and Environmental Epidemiology advance online publication, 29 May 2013; doi:10.1038/jes.2013.30. PMID:23715084

Breen, Michael S; Schultz, Bradley D; Sohn, Michael D; Long, Thomas; Langstaff, John; Williams, Ronald; Isaacs, Kristin; Meng, Qing Yu; Stallings, Casson; Smith, Luther

2013-05-29

137

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

1983-04-01

138

Evaluation of AirGIS: a GIS-based air pollution and human exposure modelling system  

DEFF Research Database (Denmark)

This study describes in brief the latest extensions of the Danish Geographic Information System (GIS)-based air pollution and human exposure modelling system (AirGIS), which has been developed in Denmark since 2001 and gives results of an evaluation with measured air pollution data. The system shows, in general, a good performance for both long-term averages (annual and monthly averages), short-term averages (hourly and daily) as well as when reproducing spatial variation in air pollution concentrations. Some shortcomings and future perspectives of the system are discussed too.

Ketzel, Matthias; Berkowicz, Ruwim

2011-01-01

139

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

140

Flashblindness and Glare Modeling of Optical Radiation.  

Science.gov (United States)

This paper reports on a mathematical model of the visual effects of optical radiation. This model is a part of the AFRL/HEDO Laser Threat Modeling Component (LTMC) laser hazard bioeffects application. It estimates the temporary reduction in visual sensiti...

W. Kosnik P. Smith

2003-01-01

 
 
 
 
141

Radiation safety in high-altitude air traffic  

Science.gov (United States)

Results of an experimental and theoretical study on dose equivalent rates at high altitudes are presented. The flight personnel flying 500 hours per year at SST cruise altitude in high latitudes (maximum of radiation) would be exposed to less than 14% of the maximum permissible dose rate (MPD) for radiation workers (5 rem/yr), averaged over the solar cycle. One-half or more is due to energetic secondary neutrons that are penetrant and highly biologically effective. Passengers would, in general, be exposed only to the low-level galactic cosmic rays, except for a relative few who encounter rare, intense, and energetic solar-particle events. If the airplane descends to subsonic altitudes during events such as that of Feb. 23, 1956 - the most intense and unique giant energy event of the last 35 years - passenger exposure even then remains at or below permissible levels (0.5 rem for the general population). Systems of radiation monitoring are briefly discussed which will prevent false alarms and which would be useful in disproving overexposure in potential malpractice suits against the airlines. In subsonic jet transports the exposure of the crews is lower by a factor 3 to 4; for passengers it is about the same for the same distance traveled. Solar events, except for giant energy events, will yield only a minor fraction of the MPD of the general population.

Foelsche, T.

1977-01-01

142

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.)

1975-08-15

143

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 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

1977-04-30

144

Data assimilation for air quality models  

DEFF Research Database (Denmark)

The chemical composition of the Earthâ??s atmosphere has major ramifications for not only human health, but also biodiversity and the climate; hence there are scientific, environmental and societal interests in accurate estimates of atmospheric chemical composition and in understanding the governing chemical and physical dynamics. Concentrations of atmospheric trace gases such as ozone, carbon monoxide and nitrogen dioxide vary substantially in space and time, and this variation can be investigated by various methods including direct measurements, remote-sensing measurements and atmospheric chemistry-transport models (CTMs). Each of these methods has their limitations: direct measurements provide only data at point locations and may not be representative of a wider area, remotely-sensed data from polar-orbiting satellites cannot investigate diurnal variation, and CTM simulations are often associated with higher uncertainties. It is possible, however, to combine information from measurements and models to moreaccurately estimate the state of the atmosphere using a statistically consistent framework known as â??data assimilationâ?. In this study, three data assimilation schemes are implemented and evaluated. The data assimilation schemes are coupled to the Danish Eulerian Hemispheric Model (DEHM), a large-scale three-dimensional off-line CTM, and the data ingested were retrievals of atmospheric composition from polar-orbiting satellites. The three assimilation techniques applied were: a three-dimensional optimal interpolation procedure (OI), an Ensemble Kalman Filter (EnKF), and a three-dimensional variational scheme (3D-var). The three assimilation procedures are described and tested. A multi-faceted approach is taken for the verification, using independent measurements from surface air-quality monitoring stations, satellite retrievals of atmospheric chemical composition and comparison with idealised simulations. The 3D-var and EnKF schemes are capable of performing multi-species adjustments, meaning that observations of different chemical components can be assimilated simultaneously. Furthermore, observations of one chemical species can be used to adjust concentrations of other (unobserved) species. Most of the methodology used in data assimilation for CTMs is based on developments within the field of numerical weather prediction, where multiparameter assimilation schemes are the norm. The verification of the 3D-var and EnKF schemes are expanded to assess the potential benefits of joint multi-species adjustments (c.f. adjusting individual species independently) or direct adjustment of unobserved species.

Silver, Jeremy David

2014-01-01

145

Radiofrequency radiation: safe working practices in the Royal Australian Air Force  

International Nuclear Information System (INIS)

The Royal Australian Air Force (RAAF) has long recognised the value of its work force and the need to preserve their health and wellbeing to achieve operational objectives. The Directorate of Air Force Safety (DAFS) is required by the Chief of the Air Staff to take all measures possible to prevent accidents and incidents in the RAAF, under the provisions of the Defence Instruction, 'Air Force Safety and Occupational Health Policy'. Consequently, the RAAF has exercised a pragmatic approach to radiofrequency radiation (RFR) and has always adopted and implemented strict exposure standards. DAFS receives technical advice on RFR from the Directorate of Telecommunications Engineering (DTELENG) and on occupational health from the Directorate General of Air Force Health Services (DGAFHS)

1988-01-01

146

A physical approach to air pollution climatological modelling in a complex site  

International Nuclear Information System (INIS)

A Gaussian climatological model which takes into account physical factors affecting air pollutant dispersion, such as nocturnal radiative inversion and mixing height evolution, associated with land breeze and sea breeze regimes, respectively, has been applied to the topographically complex area of La Spezia (a basin surrounded by hilly terrain, located on the Italian coast). Results from the measurements of the dynamic and thermodynamic structure of the lower atmosphere, obtained by a series of field experiments, are utilized in the model to calculate SO2 seasonal average concentrations. The model has been tested on eight three-monthly periods by comparing the simulated values with the ones measured at the SO2 stations of the local air pollution monitoring network. Comparison of simulated and measured values was very satisfactory and proved the applicability of the implemented model for urban planning and establishment of air quality strategies also at a topographically complex site. (author)

1980-01-01

147

Sequential box models for indoor air quality: Application to airliner cabin air quality  

Science.gov (United States)

In this paper we present the development and application of a model for indoor air quality. The model represents a departure from the standard box models typically used for indoor environments which has applicability in residences and office buildings. The model has been developed for a physical system consisting of sequential compartments which communicate only with adjacent compartments. Each compartment may contain various source and sink terms for a pollutant as well as leakage, and air transfer from adjacent compartments. The mathematical derivation affords rapid calculation of equilibrium concentrations in an essentially unlimited number of compartments. The model has been applied to air quality in the passenger cabin of three commercial aircraft. Simulations have been performed for environmental tobacco smoke (ETS) under two scenarios, CO 2 and water vapor. Additionally, concentrations in one aircraft have been simulated under conditions different from the standard configuration. Results of the simulations suggest the potential for elevated concentrations of ETS in smoking sections of non-air-recirculating aircraft and throughout the aircraft when air is recirculated. Concentrations of CO 2 and water vapor are consistent with expected results. We conclude that this model may be a useful tool in understanding indoor air quality in general and on aircraft in particular.

Ryan, P. Barry; Spengler, John D.; Halfpenny, Paul F.

148

Air quality modelling using the Met Office Unified Model: model description and initial evaluation  

Directory of Open Access Journals (Sweden)

Full Text Available The on-line air quality model AQUM (Air Quality in the Unified Model is a limited-area forecast configuration of the Met Office Unified Model which uses the UKCA (UK Chemistry and Aerosols sub-model. AQUM has been developed with two aims: as an operational system to deliver regional air quality forecasts and as a modelling system to enable air quality studies to be conducted to inform policy decisions relating to emissions controls. This paper presents a description of the model and the methods used to evaluate the performance of the forecast system. Results are presented of evaluation studies conducted for a year-long period of operational forecast trials and several past cases of poor air quality episodes. To place the model performance in context we compare AQUM ozone forecasts with those of another forecasting system, the MACC ensemble, for a 5-month period. The results demonstrate that AQUM has a large dynamic range of modelled ozone levels and has a good level of responsiveness to elevated ozone episode conditions – a characteristic which is essential for forecasting poor air quality episodes. An analysis of the variation of model skill with forecast lead-time is presented and the insights this provides to the relative sources of error in air quality modelling are discussed.

N. H. Savage

2012-10-01

149

Eight Year Climatologies from Observational (AIRS) and Model (MERRA) Data  

Science.gov (United States)

We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert. The AIRS and MERRA data are available from the Goddard Earth Sciences Data and Information Services Center (GES DISC). The AIRS climatologies we used are available for analysis with the GIOVANNI data exploration tool. (see, http://disc.gsfc.nasa.gov).

Hearty, Thomas; Savtchenko, Andrey; Won, Young-In; Theobalk, Mike; Vollmer, Bruce; Manning, Evan; Smith, Peter; Ostrenga, Dana; Leptoukh, Greg

2010-01-01

150

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

151

Coherent scattering of monochromatic RF radiation by ionization electrons of an extensive air shower  

Energy Technology Data Exchange (ETDEWEB)

The possibility of detecting extensive air showers by recording and analyzing the radio pulse produced by the reradiation of a wave moving toward the cascade disk is considered. The coherent amplification of the scattered radiation in the direction of motion of the shower is shown to be due to a relativistic effect. An example of a real facility and its peculiarities are discussed.

Filonenko, A. D., E-mail: filonenko_ad@dsip.net [Dal' Eastern Ukrainian National University (Ukraine)

2013-10-15

152

Urban Air Quality Modelling with AURORA: Prague and Bratislava  

Science.gov (United States)

The European Commission, in its strategy to protect the health of the European citizens, states that in order to assess the impact of air pollution on public health, information on long-term exposure to air pollution should be available. Currently, indicators of air quality are often being generated using measured pollutant concentrations. While air quality monitoring stations data provide accurate time series information at specific locations, air quality models have the advantage of being able to assess the spatial variability of air quality (for different resolutions) and predict air quality in the future based on different scenarios. When running such air quality models at a high spatial and temporal resolution, one can simulate the actual situation as closely as possible, allowing for a detailed assessment of the risk of exposure to citizens from different pollutants. AURORA (Air quality modelling in Urban Regions using an Optimal Resolution Approach), a prognostic 3-dimensional Eulerian chemistry-transport model, is designed to simulate urban- to regional-scale atmospheric pollutant concentration and exposure fields. The AURORA model also allows to calculate the impact of changes in land use (e.g. planting of trees) or of emission reduction scenario's on air quality. AURORA is currently being applied within the ESA atmospheric GMES service, PASODOBLE (http://www.myair-eu.org), that delivers information on air quality, greenhouse gases, stratospheric ozone, … At present there are two operational AURORA services within PASODOBLE. Within the "Air quality forecast service" VITO delivers daily air quality forecasts for Belgium at a resolution of 5 km and for the major Belgian cities: Brussels, Ghent, Antwerp, Liege and Charleroi. Furthermore forecast services are provided for Prague, Czech Republic and Bratislava, Slovakia, both at a resolution of 1 km. The "Urban/regional air quality assessment service" provides urban- and regional-scale maps (hourly resolution) for air pollution and human exposure statistics for an entire year. So far we concentrated on Brussels, Belgium and the Rotterdam harbour area, The Netherlands. In this contribution we focus on the operational forecast services. Reference Lefebvre W. et al. (2011) Validation of the MIMOSA-AURORA-IFDM model chain for policy support: Modeling concentrations of elemental carbon in Flanders, Atmospheric Environment 45, 6705-6713

Veldeman, N.; Viaene, P.; De Ridder, K.; Peelaerts, W.; Lauwaet, D.; Muhammad, N.; Blyth, L.

2012-04-01

153

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.)

1990-09-03

154

Radiation induced peroxidation in model lipid systems  

International Nuclear Information System (INIS)

In the studies of radiation induced lipid peroxidation, lecithin-liposomes and aqueous micellar solutions of sodium linoleate (or linoleic acid) have been used as models of lipid membrane systems. The liposomes and aqueous linoleate micelles were irradiated in the presence of O2 and N2O/O2 (80/20 v/v). The peroxidation was initiated using gamma radiation from 60Co radiation source and was monitored by measuring the increase in absorbance of conjugated diene at 232 nm and by the thiobarbituric acid (TBA) test. The oxidation products were also identified by GLC and GLC-MS analysis. (author)

1981-01-01

155

Improving Air-Conditioner and Heat Pump Modeling (Presentation)  

Energy Technology Data Exchange (ETDEWEB)

A new approach to modeling residential air conditioners and heat pumps allows users to model systems by specifying only the more readily-available SEER/EER/HSPF-type metrics. Manufacturer data was used to generate full sets of model inputs for over 450 heat pumps and air conditioners. A sensitivity analysis identified which inputs can be safely defaulted 'behind-the-scenes' without negatively impacting the reliability of energy simulations.

Winkler, J.

2012-03-01

156

Generation and analysis of the European air quality model  

Energy Technology Data Exchange (ETDEWEB)

The paper presents a large scale nonlinear model which is used for supporting international negotiations aimed at improving air quality in Europe. The model helps to identify cost effective measures for reducing air pollution emissions and to examine the resulting concentrations of tropospheric ozone, acidification and eutrophication. Several methodological and technical issues related to the specification, generation and optimization-based analysis of large nonlinear models for decision support that are of a more general interest are presented. (author)

Makowski, M. [International Institute for Applied Systems Analysis, Laxenburg (Austria)

1999-07-01

157

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

1997-09-08

158

10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities  

Science.gov (United States)

...2009-01-01falseDerived Air Concentrations (DAC) for Controlling Radiation Exposure to...Part 835âDerived Air Concentrations (DAC) for Controlling Radiation Exposure to...accordance with § 835.603(d).The DAC values are given for individual...

2009-01-01

159

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

160

Infrared radiation models for atmospheric ozone  

Science.gov (United States)

A hierarchy of line-by-line, narrow-band, and broadband infrared radiation models are discussed for ozone, a radiatively important atmospheric trace gas. It is shown that the narrow-band (Malkmus) model is in near-precise agreement with the line-by-line model, thus providing a means of testing narrow-band Curtis-Godson scaling, and it is found that this scaling procedure leads to errors in atmospheric fluxes of up to 10 percent. Moreover, this is a direct consequence of the altitude dependence of the ozone mixing ratio. Somewhat greater flux errors arise with use of the broadband model, due to both a lesser accuracy of the broadband scaling procedure and to inherent errors within the broadband model, despite the fact that this model has been tuned to the line-by-line model.

Kratz, David P.; Ces, Robert D.

1988-01-01

 
 
 
 
161

Modeling radiation effects at the tissue level  

Energy Technology Data Exchange (ETDEWEB)

For the understanding of radiation action in humans, a synergistic approach of experiments and quantitative modeling of working hypotheses is necessary. A large set of experimental data at the single-cell level are available, and biophysical modeling of radiation action has so far mostly concentrated on the first phases of radiation interaction with the biomolecules, and later biochemical stages including DNA breakage, repair, and the formation of chromosomal aberrations. The models can be extended to cell killing and transformation, but so far still using a single-cell (clonal expansion) approach. On the contrary, new experimental evidence points to the microenvironment and the tissue level as a critical radiation target for late effects, and to epigenetic and signaling mechanisms as mediators of radiation damage. This higher structural level is generally ignored in modeling, owing to its complexity and to the lack of experimental data. In this paper we will highlight the requirements for specific experimental approaches targeting the tissue/microenvironment level and the most promising available experimental models. (authors)

Muller, M.; Durante, M.; Stocker, H. [GSI Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Muller, M.; Stocker, H. [Frankfurt Institute for Advanced Studies (FIAS), Frankfurt am Main (Germany); Durante, M. [Technical University of Darmstadt, Darmstadt (Germany); Merz, F.; Bechmann, I. [Institute of Anatomy, University of Leipzig, Leipzig (Germany)

2010-10-15

162

Air  

…below the level at which they can do significant harm. Information & advice from us * Air quality * Emissions to air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality…

163

Air  

…the level at which they can do significant harm. Information & advice from us * Air quality * Emissions to air * Air pollution incidents * Ozone depletion * Acid rain * Pollution inventory data * National atmospheric emissions inventory * National Environmental Technology Centre * Local air quality management…

164

Improvement of local air coolers model in ISAAC  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to assess a new local air coolers model in ISAAC 2.0, as ISAAC 1.0 could model local air coolers only at two locations. In the new model, local air coolers up to twelve locations could be handled. Large LOCA and loss of feed water sequences were selected for the model comparison. Two cases were analyzed with ISAAC 2.0: one with 6 local air coolers in one of the fueling machine room and in the steam generator room, respectively, and the other with 3 local air coolers at both fueling machine room and 6 local air coolers in the steam generator room. The study assumes that the safety systems such as emergency core cooling system, shield cooling system and moderator cooling system are unavailable. According to the ISAAC 2.0 results, the new local air coolers model showed almost no difference between two cases. Also it was found that as the location of LACs increased, the new model worked properly and the effect of LACs was consistent regardless the accident initiators.

Kim, See Darl; Kim, Dong Ha; Park, Soo Yong; Paik, Chan Young

2004-02-01

165

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

166

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

2007-08-01

167

Propagation speed of {gamma}-radiation in air  

Energy Technology Data Exchange (ETDEWEB)

To perform such measurements the availability of a gamma radiation source in which two {gamma}-rays are emitted simultaneously in opposite directions -as already used(5,6) as well as applied in the present case- turns out to be essential to the feasibility of the experiment, as far as no reflection techniques could be used. Such suitable source was the positron emitter {sup 22}Na placed in a metal container in which the positrons are stopped and annihilated when reacting with the medium electrons, in such way originating -as it is very well established from momentum/energy conservation laws(7)- two {gamma}-rays, energy 511 KeV each, both emitted simultaneously in opposite directions. In all these previous experiments were used photomultiplier detectors coupled to NaI(Tl) crystal scintillators, which have a good energy resolution but a deficient time resolution for such purposes. Presently, as an innovatively improvement, were used BaF{sub 2} and CsF crystal scintillators which display a much better time resolution. (author)

Cavalcante, Jose T.P.D.; Silva, Paulo R.J.; Saitovitch, Henrique [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Macedo Junior, Marcelo A.V. [Centro Federal de Educacao Tecnologica de Quimica de Nilopolis (CEFET), RJ (Brazil)

2008-07-01

168

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

169

Predictive modeling of a radiative shock system  

International Nuclear Information System (INIS)

A predictive model is constructed for a radiative shock experiment, using a combination of a physics code and experimental measurements. The CRASH code can model the radiation hydrodynamics of the radiative shock launched by the ablation of a Be drive disk and driven down a tube filled with Xe. The code is initialized by a preprocessor that uses data from the Hyades code to model the initial 1.3 ns of the system evolution, with this data fit over seven input parameters by a Gaussian process model. The CRASH code output for shock location from 320 simulations is modeled by another Gaussian process model that combines the simulation data with eight field measurements of a CRASH experiment, and uses this joint model to construct a posterior distribution for the physical parameters of the simulation (model calibration). This model can then be used to explore sensitivity of the system to the input parameters. Comparison of the predicted shock locations in a set of leave-one-out exercises shows that the calibrated model can predict the shock location within experimental uncertainty.

2011-09-01

170

A photochemical box model for urban air quality study  

Science.gov (United States)

The photochemical box model (PBM) developed in the present study is based on the principle of mass conservation. It has a horizontal domain of the size of a typical city and a vertical dimension defined by the mixed-layer height. The concentration of any pollutant is determined by horizontal advection, vertical entrainment, source emissions and chemical reactions. A one-dimensional high resolution boundary layer model by Blackadar ( Preprints, Third Symp. on Atmospheric Turbulence, Diffusion, and Air Quality, Raleigh, Am. Met. Soc., pp. 443-447, 1976; Advances in Environmental Sciences and Engineering, Vol. 1, No. 1 (edited by Pfafflin J. and Ziegler E.), pp. 50-85. Gordon and Breach, New York, 1979) has been incorporated in the PBM and further developed to consider the effect of urban heat islands in the simulation of mixed layer height. The predicted mixed-layer heights compare very well with observations. The gas phase chemical kinetic mechanism used in the Regional Acid Deposition Model II (RADM2) and that of an earlier version of PBM have been used to calculate the contributions of chemical reactions to the changes of pollutant concentrations. Detailed analysis and comparisons of the two chemical mechanisms have been made. The simulated pollutant concentrations using both chemical mechanisms are in very good agreement with available observations for CO, NO, NO 2 and O 3. A radiative transfer model developed by Madronich ( J. geophys. Res.92, 9740-9752, 1987) has been incorporated in the PBM for the calculation of actinic flux and photolytic rate constants. Height-averaged and radiation-corrected photolytic rate constants are used for the photochemical reactions. Budget analyses conducted for CO, NO, NO 2 and O 3 have enhanced our understanding of the relative contributions of horizontal advection, vertical entrainment, source emissions and chemical reactions to the overall rate of change of their concentrations. Model predictions are not sensitive to the large number of peroxy radical-peroxy radical reactions in the RADM2 chemical mechanism under urban conditions.

Jin, Shengxin; Demerjian, Kenneth

171

A FEDERATED PARTNERSHIP FOR URBAN METEOROLOGICAL AND AIR QUALITY MODELING  

Science.gov (United States)

Recently, applications of urban meteorological and air quality models have been performed at resolutions on the order of km grid sizes. This necessitated development and incorporation of high resolution landcover data and additional boundary layer parameters that serve to descri...

172

Correlation between indoor radon concentration and dose rate in air from terrestrial gamma radiation in Japan.  

Science.gov (United States)

A correlation between the indoor radon concentration and dose rate in air from terrestrial gamma radiation is studied using the results of nationwide indoor radon and external exposure surveys, although the surveys were not conducted at the same time nor at the same location. The radon concentration shows a log-normal-like distribution, whereas the terrestrial gamma radiation dose rate in air shows a normal-like distribution. A log-linear scatterplot for each pair of the indoor radon concentration and gamma-ray dose rate in air in each city reveals a clear relationship. The average, maximum, and minimum as well as regression line of radon concentration were found to increase with the gamma-ray dose rate in air. The group in higher quantile of radon concentration shows larger dependence on the gamma-ray dose rate. The rate of increase of radon concentration with the gamma-ray dose rate in air depends on the house structure. The wooden house has a larger rate of increase than the concrete house, and the regression lines cross at high air dose rate. Based on the finding in the present study a certain criterion level of air dose rate could be established and used for an effective survey to find out which houses might require a remedial action in conjunction with other screening tools. The criterion level of air dose rate might be more effective if the level is set for each house structure since the rate of increase of radon concentration depends on house structure. PMID:9721838

Fujimoto, K

1998-09-01

173

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 (TiO2) 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 TiO2 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 TiO2 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

174

Quantifying the influence of local meteorology on air quality using generalized additive models  

Science.gov (United States)

Recent acknowledgement of the sensitivity of air quality to changes in climate has initiated a closer examination of the relationships between meteorology and air quality. This paper presents the estimated response of daily air pollutant concentrations in Melbourne, Australia to local-scale meteorology. The meteorological-pollutant relationships have been assessed after controlling for long-term trends, seasonality, weekly emissions, spatial variation, and temporal persistence using the framework of generalized additive models (GAMs). Overall, results found that the aggregate impact of meteorological variables in the models explained 26.3% of the variance in O 3, 21.1% in PM 10, and 26.7% in NO 2. This indicates that meteorology - at the local-scale, is a relatively strong driver of air quality in Melbourne. Analysis of partial residuals plots found that changes in temperature, particularly when above 35 °C, resulted in the strongest positive response for O 3 (150%), PM 10 (150%) and NO 2 (120%). Other variables (boundary layer height, winds, water vapor pressure, radiation, precipitation, and mean sea-level pressure) displayed some importance for one or more of the pollutants, but their impact in the models was less pronounced. In sum, we provide results that form a solid foundation for understanding the importance of local-scale meteorology as a driver of regional air pollution. Additionally, these results can be used to provide a window into how changes in climate may affect air quality.

Pearce, John L.; Beringer, Jason; Nicholls, Neville; Hyndman, Rob J.; Tapper, Nigel J.

2011-02-01

175

Significance of the air pathway in contributing radiation dose to biota  

International Nuclear Information System (INIS)

A screening methodology was developed as part of the U.S. Department of Energy's (DOE) graded approach for evaluating radiation doses to aquatic and terrestrial biota from contaminants released into the environment. Included in the graded approach methodology were limiting media concentrations for water, soil, and sediment for twenty-three radionuclides. These concentrations were designed to restrict potential doses to biota below biota dose limits (i.e., dose rate guidelines) specified within existing and proposed DOE regulations. While implicitly included in the derivation of limiting media concentrations, separate biota concentration guides (BCGs) for air were not provided. This paper presents BCGs for air developed within the context and framework of the DOE methodology. The same twenty-three radionuclides are examined. Three air exposure pathways are considered: external exposure (cloudshine), inhalation, and absorption. Allometric equations are used to assess exposure via inhalation, and simplifying assumptions (similar to those used in human dose calculations) are used to assess external and absorption pathways. For purposes of comparison, the air BCGs are compared to current DOE air concentration limits for humans. This analysis validated the initial assumption that the air pathway is unlikely to be a major exposure pathway for biota. In addition, limits for humans are sufficiently restrictive that at sites with active air releases no populations of terrestrial animals or plants are likely to receive significant doses from this exposure pathway. (author)

2003-05-01

176

Infrared radiation models for atmospheric methane  

Science.gov (United States)

Mutually consistent line-by-line, narrow-band and broad-band infrared radiation models are presented for methane, a potentially important anthropogenic trace gas within the atmosphere. Comparisons of the modeled band absorptances with existing laboratory data produce the best agreement when, within the band models, spurious band intensities are used which are consistent with the respective laboratory data sets, but which are not consistent with current knowledge concerning the intensity of the infrared fundamental band of methane. This emphasizes the need for improved laboratory band absorptance measurements. Since, when applied to atmospheric radiation calculations, the line-by-line model does not require the use of scaling approximations, the mutual consistency of the band models provides a means of appraising the accuracy of scaling procedures. It is shown that Curtis-Godson narrow-band and Chan-Tien broad-band scaling provide accurate means of accounting for atmospheric temperature and pressure variations.

Cess, R. D.; Kratz, D. P.; Caldwell, J.; Kim, S. J.

1986-01-01

177

Utilization of radon progeny in air for education experiment on radiation  

International Nuclear Information System (INIS)

Radon progeny with short half-lives in the natural air was utilized in the education experiment on radiation that is for the students in the university of Tokyo. Advantage points of the radon progeny are; 1) their short half-lives around 30-50 minutes whose feature is adequate to draw the decay curve in the class and 2) that they exist in the natural air. The most important point of this education experiment is to perform sampling and measuring the radioactivity in the natural area, not in the radiation controlled area. Through the procedure, the students can understand that natural radio-nuclides surely exist around us. Sampling time is 30 minutes at a flow rate of around 60 litters per minute and a glass-fiber filter of GF/F is used, waiting time is one minute and measuring time is sequence of 10 times of 5 minutes (total measuring time; 35 minutes). The total experiment time is around 100 minutes. In the home-tasks, they calculate the radon progeny's concentration in air using the alpha decay curve of the radon progeny on the sampling filter: In addition, they investigate and learn the natural radiation/radioactivity. The radon progeny is useful and effective natural radioactivity for the radiation education. (author)

2003-11-01

178

HANDBOOK FOR PREPARING USER'S GUIDES FOR AIR QUALITY MODELS  

Science.gov (United States)

Suggestions for content, order of material, style, and format are set forth for modelers to follow when writing user's guides for air quality models. A review of coding techniques conducive to model documentation is presented. This material was compiled by the Meteorology and Ass...

179

The Double Counting Problem in Neighborhood Scale Air Quality Modeling  

Science.gov (United States)

Air quality varies considerably within megacities. In certain neighborhoods concentrations of toxic air contaminants (TACs) can be appreciably higher than that in other neighborhoods of the same city. These pockets of high concentrations are associated with both transport of TACs from other areas and local emissions. In order to assess the health risks imposed by TACs at neighborhood scale and to develop strategies of abatement, neighborhood scale air quality modeling is needed. In 1999, the California Air Resources Board (ARB) established the Neighborhood Assessment Program (NAP) - a program designed to develop assessment tools for evaluating and understanding air quality in California communities. As part of the Neighborhood Assessment Program, ARB is conducting research on neighborhood-scale modeling methodologies. Two criteria are suggested to select a neighborhood scale air quality modeling system that can be used to assess concentrations of TACs: scientific soundness and balancing computational requirements. The latter criterion ensures that as many interested parties as possible can participate the process of air quality modeling so that they have a better understanding of air quality issues and make best use of air quality modeling results in their neighborhoods. Based on these two selection criteria a hybrid approach is recommended. This hybrid approach is a combination of using both a regional scale air quality model to assess the contributions from sources that are not located within the neighborhood of interest and a microscale model to assess the impact from the local sources that are within the neighborhood. However, one of the modeling system selection criteria, balancing computational requirements, dictates that all sources (both within and outside the neighborhood of interest) must be included in the regional scale modeling. A potential problem, referred to as double counting, arises because some local sources are included in both regional and microscale modeling. To address this issue, a box model is developed to calculate the impact of double counted sources so that their effect on the total concentration (i.e., concentration due to all sources) can be minimized or even eliminated.

Du, S.; Hughes, V.; Woodhouse, L.; Servin, A.

2004-12-01

180

Data driven modelling of vertical atmospheric radiation  

International Nuclear Information System (INIS)

In the Czech Hydrometeorological Institute (CHMI) there exists a unique set of meteorological measurements consisting of the values of vertical atmospheric levels of beta and gamma radiation. In this paper a stochastic data-driven model based on nonlinear regression and on nonhomogeneous Poisson process is suggested. In the first part of the paper, growth curves were used to establish an appropriate nonlinear regression model. For comparison we considered a nonhomogeneous Poisson process with its intensity based on growth curves. In the second part both approaches were applied to the real data and compared. Computational aspects are briefly discussed as well. The primary goal of this paper is to present an improved understanding of the distribution of environmental radiation as obtained from the measurements of the vertical radioactivity profiles by the radioactivity sonde system. - Highlights: ? We model vertical atmospheric levels of beta and gamma radiation. ? We suggest appropriate nonlinear regression model based on growth curves. ? We compare nonlinear regression modelling with Poisson process based modeling. ? We apply both models to the real data.

2011-12-01

 
 
 
 
181

Radiative leptogenesis in minimal seesaw models  

CERN Multimedia

In the framework of seesaw models with only two heavy Majorana neutrinos, nonzero leptonic asymmetries can be radiatively generated when exact heavy neutrino mass degeneracy ($M_1=M_2=M$) is imposed at a scale $\\Lambda_D > M$. For a specific case, we show that an acceptable value for the baryon asymmetry of the Universe can be obtained considering thermal leptogenesis.

Joaquim, F R

2005-01-01

182

Modeling the earth’s cosmic radiation  

International Nuclear Information System (INIS)

In this study, we use physics based cross sections and the radiation transport code MCNPX to develop a purely physics based global model of cosmogenic nuclide production. Modeling the earth as a series of concentric, spherical shells of various media, we propagate the radiation cascade resulting from bombarding the model with primary protons and helium nuclei. The hadronic component of the radiation cascade is tracked throughout the atmosphere as well as the upper region of simple, rock earth-planets. Tallying the energy spectrum throughout the geometry allows us to fold the energy dependent flux with excitation functions to determine nuclide specific spallogenic production rates and attenuation lengths. Using these results, we characterize facets of the radiation cascade and resulting productions rates that are currently unaccounted for in modern scaling schemes. Preliminary results of our deep atmosphere model show nuclide dependent attenuation lengths, therefore, altitude dependent production ratios. Preliminary results from simple, homogeneous rock planets show production rate depth profiles that diminish at a rate inconsistent with a simple exponential, the currently accepted assumption.

2013-01-01

183

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

1997-07-17

184

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

2005-05-01

185

Experimental data on a pulse shape of Cherenkov radiation of extensive air showers and their analysis  

International Nuclear Information System (INIS)

Measurements of a pulse duration of the Cherenkov radiation of extensive air showers are carried out using the Samarkand state university device. Calculations of atmospheric cascades and forms of corresponding pulses of the Cherenkov radiation are performed. Theoretical data are obtained for the distances of 200, 300, 400 m from the shower axis for the primary energy of 1016 eV. The magnitude of mean duration at a distance of 200 m constitutes tau=11.4+-0.9 ns. The mean maximum depth for the showers with a mean energy of E=6x1015 eV constitutes 596+-19 gxcm-2

1982-09-01

186

Supersymmetric standard model and radiative meson decay  

Energy Technology Data Exchange (ETDEWEB)

I give a review on the generation-changing interactions of the supersymmetric standard model based on grand unification and N=1 supergravity. These interactions could make sizable effects on rare processes related to B-mesons. The decay b{yields}s{gamma} is discussed in particular. It is shown that the inclusive branching ratio of the radiative B-meson decay is deviated from the standard model prediction in nontrivial ranges for parameter values. ((orig.))

Oshimo, N. [Instituto Superior Tecnico, Lisbon (Portugal). Grupo Teorico de Altas Energias, CFIF

1995-01-01

187

Supersymmetric standard model and radiative meson decay  

Science.gov (United States)

I give a review on the generation-changing interactions of the supersymmetric standard model based on grand unification and N = 1 supergravity. These interactions could make sizable effects on rare processes related to B-mesons. The decay b ? s? is discussed in particular. It is shown that the inclusive branching ratio of the radiative B-meson decay is deviated from the standard model prediction in nontrivial ranges for parameter values.

Oshimo, Noriyuki

1995-01-01

188

Supersymmetric standard model and radiative meson decay  

International Nuclear Information System (INIS)

I give a review on the generation-changing interactions of the supersymmetric standard model based on grand unification and N=1 supergravity. These interactions could make sizable effects on rare processes related to B-mesons. The decay b?s? is discussed in particular. It is shown that the inclusive branching ratio of the radiative B-meson decay is deviated from the standard model prediction in nontrivial ranges for parameter values. ((orig.))

1995-01-01

189

Chemistry-radiation interactions in methane/air counterflow partially premixed flames  

Energy Technology Data Exchange (ETDEWEB)

A computational study of the effects of radiation heat loss on methane/air counterflow partially premixed flames was completed with detailed chemical kinetics including NO{sub x} formation reactions (GRI-Mech 2.11). The radiation heat loss is calculated in the optically thin limit using Planck mean absorption coefficients of CO{sub 2}, H{sub 2}O, CO, and CH{sub 4}. The temperature dependence of the Planck mean absorption coefficients is considered using fourth order polynomial fits to the results of narrow band emission calculations. The effects of radiation heat loss on the flame structure and NO formation for different stretch rates were studied by comparing results with and without radiation heat loss. The effects of radiation heat loss are significant for low stretch rates. The effects of radiation heat loss counteract the effects of stretch rate (proportional to the injection velocity for the present configuration). The net result is that the effects of stretch rate on flame structure and NO production are smaller than those anticipated based on computations without radiation heat loss. The radiation heat loss leads to a decrease in the rate of the thermal initiation reaction for the lower velocities, and a decrease in the rate of the prompt initiation reaction for the higher velocities, leading to low NO concentrations and NO emission indices. The effects of gas phase radiation heat loss on the partially premixed flame are stronger than those on the diffusion flame because of the broader profiles of the radiating species and the temperature.

Zhu, X.L.; Gore, J.P.; Takeno, T.

1999-07-01

190

Linear and nonlinear modeling approaches for urban air quality prediction.  

Science.gov (United States)

In this study, linear and nonlinear modeling was performed to predict the urban air quality of the Lucknow city (India). Partial least squares regression (PLSR), multivariate polynomial regression (MPR), and artificial neural network (ANN) approach-based models were constructed to predict the respirable suspended particulate matter (RSPM), SO(2), and NO(2) in the air using the meteorological (air temperature, relative humidity, wind speed) and air quality monitoring data (SPM, NO(2), SO(2)) of five years (2005-2009). Three different ANN models, viz. multilayer perceptron network (MLPN), radial-basis function network (RBFN), and generalized regression neural network (GRNN) were developed. All the five different models were compared for their generalization and prediction abilities using statistical criteria parameters, viz. correlation coefficient (R), standard error of prediction (SEP), mean absolute error (MAE), root mean squared error (RMSE), bias, accuracy factor (A(f)), and Nash-Sutcliffe coefficient of efficiency (E(f)). Nonlinear models (MPR, ANNs) performed relatively better than the linear PLSR models, whereas, performance of the ANN models was better than the low-order nonlinear MPR models. Although, performance of all the three ANN models were comparable, the GRNN over performed the other two variants. The optimal GRNN models for RSPM, NO(2), and SO(2) yielded high correlation (between measured and model predicted values) of 0.933, 0.893, and 0.885; 0.833, 0.602, and 0.596; and 0.932, 0.768 and 0.729, respectively for the training, validation and test sets. The sensitivity analysis performed to evaluate the importance of the input variables in optimal GRNN revealed that SO(2) was the most influencing parameter in RSPM model, whereas, SPM was the most important input variable in other two models. The ANN models may be useful tools in the air quality predictions. PMID:22542239

Singh, Kunwar P; Gupta, Shikha; Kumar, Atulesh; Shukla, Sheo Prasad

2012-06-01

191

Modeling and simulation of desiccant wheel for air conditioning  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the modeling of a desiccant wheel used for dehumidifying the ventilation air of an air-conditioning system. The simulation of the combined heat and mass transfer processes that occur in a solid desiccant wheel is carried out with MATLAB Simulink. Using the numerical method, the performance of an adiabatic rotary dehumidifier is parametrically studied, and the optimal rotational speed is determined by examining the outlet adsorption-side humidity profiles. The solutions of the simulation at different conditions used in air dehumidifier have been investigated according to the previous published studies. The model is validated through comparison of the simulated results with the published actual values of an experimental work. This method is useful to study and modelling of solid desiccant dehumidification and cooling system. The modeling solutions are used to develop simple correlations for the outlet air conditions of humidity and temperature of air through the wheel as a function of the physically measurable input variables. These correlations will be used to simulate the desiccant cooling cycle in an heating/ventilation/air conditioning system in order to define the year round efficiency. (author)

Nia, F. E.; Saidi, M. H. [Mechanical Engineering Department, Sharif University of Technology, Tehran (Iran); Paassen, D. van [Mechanical Maritime and Materials Engineering, Delft University of Technology, Delft (Netherlands)

2006-10-15

192

Studies on curing effect of phosphite monomer by EB radiation in the air  

International Nuclear Information System (INIS)

A new type phosphite active monomer was synthesized. The resisting oxygen inhibition effect of this monomer and the effects of irradiation dose and concentration of phosphite active monomer on curing were studied. At the same time, curing results were analysed, through gel content and IR spectrum. The excellent resisting oxygen inhibition result of this phosphite active monomer was shown by experiments. EB radiation curing in the air was successfully carried out by the phosphite active monomer. (author)

2000-03-01

193

Steady-state computer design model for air-to-air heat pumps  

Energy Technology Data Exchange (ETDEWEB)

The ORNL Heat Pump Design Model is a FORTRAN-IV computer program to predict the steady-state performance of conventional, vapor compression, electrically-driven, air-to-air heat pumps in both heating and cooling modes. This model is intended to serve as an analytical design tool for use by heat pump manufacturers, consulting engineers, research institutions, and universities in studies directed toward the improvement of heat pump performance. The Heat Pump Design Model allows the user to specify: system operating conditions, compressor characteristics, refrigerant flow control devices, fin-and-tube heat exchanger parameters, fan and indoor duct characteristics, and any of ten refrigerants. The model will compute: system capacity and COP (or EER), compressor and fan motor power consumptions, coil outlet air dry- and wet-bulb temperatures, air- and refrigerant-side pressure drops, a summary of the refrigerant-side states throughout the cycle, and overall compressor efficiencies and heat exchanger effectiveness. This report provides thorough documentation of how to use and/or modify the model.

Fischer, S.K.; Rice, C.K.

1981-12-01

194

Air quality modeling of geothermal power plants in complex terrain  

Energy Technology Data Exchange (ETDEWEB)

Commercial energy development at the Geysers KGRA, California--the world's largest producing geothermal field--is confronted with increasingly more stringent air quality impact assessment requirements for not only regulated pollutants (e.g., hydrogen sulfide and primary particulates) but also unregulated species including benzene, ammonia, arsenic, Radon/sup 222/, boron, and mercury. An integrated program of ambient aerometric monitoring, tracer diffusion experiments, cooling tower plume rise studies, and numerical air quality simulation modeling was conducted for this mountainous region to provide estimates of potential short term (i.e., about 1 hour) impacts attributable to development of the Geysers steam resource. A series of atmospheric tracer diffusion experiments, focusing on aerodynamic downwash, nocturnal drainage, fumigation, and limited vertical mixing were conducted to provide a basis for air quality model performance evaluation. Upper air meteorological measurements and cooling tower plume rise studies were performed to develop data useful in evaluating windfield and plume rise submodels.

Tesche, T.W.

1982-10-01

195

Air-quality modelling in the Lake Baikal region.  

Science.gov (United States)

In this paper, we assess the status of the air quality in the Lake Baikal region which is strongly influenced by the presence of anthropogenic pollution sources. We combined the local data, with global databases, remote sensing imagery and modelling tools. This approach allows to inventorise the air-polluting sources and to quantify the air-quality concentration levels in the Lake Baikal region to a reasonable level, despite the fact that local data are scarcely available. In the simulations, we focus on the month of July 2003, as for this period, validation data are available for a number of ground-based measurement stations within the Lake Baikal region. PMID:19496003

Van de Vel, Karen; Mensink, Clemens; De Ridder, Koen; Deutsch, Felix; Maes, Joachim; Vliegen, Jo; Aloyan, Artash; Yermakov, Alexander; Arutyunyan, Vardan; Khodzher, Tamara; Mijling, Bas

2010-06-01

196

Radiative torques: analytical model and basic properties  

Science.gov (United States)

We attempt to get a physical insight into grain alignment processes by studying basic properties of radiative torques (RATs). For this purpose we consider a simple toy model of a helical grain that reproduces well the basic features of RATs. The model grain consists of a spheroidal body with a mirror attached at an angle to it. Being very simple, the model allows analytical description of RATs that act upon it. We show a good correspondence of RATs obtained for this model and those of irregular grains calculated by DDSCAT. Our analysis of the role of different torque components for grain alignment reveals that one of the three RAT components does not affect the alignment, but induces only for grain precession. The other two components provide a generic alignment with grain long axes perpendicular to the radiation direction, if the radiation dominates the grain precession, and perpendicular to magnetic field, otherwise. The latter coincides with the famous predictions of the Davis-Greenstein process, but our model does not invoke paramagnetic relaxation. In fact, we identify a narrow range of angles between the radiation beam and the magnetic field, for which the alignment is opposite to the Davis-Greenstein predictions. This range is likely to vanish, however, in the presence of thermal wobbling of grains. In addition, we find that a substantial part of grains subjected to RATs gets aligned with low angular momentum, which testifies that most of the grains in diffuse interstellar medium do not rotate fast, that is, rotate with thermal or even subthermal velocities. This tendency of RATs to decrease grain angular velocity as a result of the RAT alignment decreases the degree of polarization, by decreasing the degree of internal alignment, that is, the alignment of angular momentum with the grain axes. For the radiation-dominated environments, we find that the alignment can take place on the time-scale much shorter than the time of gaseous damping of grain rotation. This effect makes grains a more reliable tracer of magnetic fields. In addition, we study a self-similar scaling of RATs as a function of ?/aeff. We show that the self-similarity is useful for studying grain alignment by a broad spectrum of radiation, that is, interstellar radiation field.

Lazarian, A.; Hoang, Thiem

2007-07-01

197

Response of air-filled ion chambers to high-intensity radiation pulses  

Energy Technology Data Exchange (ETDEWEB)

Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

Plum, M.; Brown, D.

1993-01-01

198

Response of air-filled ion chambers to high-intensity radiation pulses  

Energy Technology Data Exchange (ETDEWEB)

Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

Plum, M.; Brown, D.

1993-06-01

199

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 cm"3 and 30 cm"3 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 cm"3 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 On

2002-11-25

200

A coupled surface/subsurface flow model accounting for air entrapment and air pressure counterflow  

DEFF Research Database (Denmark)

This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive wave) shallow flow and two-phase flow in a porous medium. The simultaneous mass transfer between the soil, overland, and atmosphere compartments is achieved by upgrading a fully established leakance concept for overland-soil liquid exchange to an air exchange flux between soil and atmosphere. In a new algorithm, leakances operate as a valve for gas pressure in a liquid-covered porous medium facilitating the simulation of air out-break events through the land surface. General criteria are stated to guarantee stability in a sequential iterative coupling algorithm and, in addition, for leakances to control the mass exchange between compartments. A benchmark test, which is based on a classic experimental data set on infiltration excess (Horton) overland flow, identified a feedback mechanism between surface runoff and soil air pressures. Our study suggests that air compression in soils amplifies surface runoff during high precipitation at specific sites, particularly in near-stream areas. © 2013 Springer-Verlag Berlin Heidelberg.

Delfs, Jens Olaf; Wang, Wenqing

2013-01-01

 
 
 
 
201

Measuring Air Temperature in Glazed Ventilated Facades in the Presence of Direct Solar Radiation  

DEFF Research Database (Denmark)

A distinctive element of buildings with a double glazed façade is naturally or mechanically driven flow in a ventilated cavity. Accurate air temperature measurements in the cavity are crucial to evaluate the dynamic performance of the façade, to predict and control its behavior as a significant part of the complete ventilation system. Assessment of necessary cooling/heating loads and of the whole building energy performance will then depend on the accuracy of measured air temperature. The presence of direct solar radiation is an essential element for the façade operation, but it can heavily affect measurements of air temperature and may lead to errors of high magnitude using bare thermocouples and even adopting shielding devices. Two different research groups, from Aalborg University and Politecnico di Torino, tested separately various techniques to shield thermocouples from direct irradiance, in order to achieve an accurate and reliable way to measure the air temperature reducing the error caused by radiation. Experiments include bare thermocouple, naturally and mechanically ventilated shielded thermocouples, mechanically ventilated thermocouple with double shielding, silver coated thermocouples and screens. In both tests mechanically ventilated (single) shielding devices provide better results than naturally ventilated ones. A few of the best performing techniques were compared between two research groups and a comparison shows good agreement of the results.

Kalyanova, Olena; Zanghirella, Fabio

2007-01-01

202

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)

1995-12-01

203

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

204

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

205

Modeling air entrainment in plunging jet using 3DYNAFS  

CERN Document Server

As the liquid jet plunges into a free surface, significant air is entrained into the water and forms air pockets. These air pockets eventually break up into small bubbles, which travel downstream to form a bubbly wake. To better understand the underlying flow physics involved in the bubble entrainment, in the linked videos, air entrainment due to a water jet plunging onto a pool of stationary water was numerically studied by using the 3DYNAFS software suit. The flow field is simulated by directly solving the Navier-Stokes equations through the viscous module, 3DYNAFS-VIS, using a level set method for capturing the free surface. The breakup of entrained air pockets and the resulting bubbly flow were modeled by coupling 3DYNAFS-VIS with a Lagrangian multi-bubble tracking model, 3DYNAFS-DSM (Hsiao & Chahine, 2003), which emits bubbles into the liquid according to local liquid/gas interface flow conditions based on the sub-grid air entrainment modeling proposed by Ma et al. (2011), and tracks all bubbles in t...

Hsiao, Chao-Tsung; Wu, Xiongjun; Chahine, Georges L

2011-01-01

206

Air flow modeling in deep wells : application to mining ventilation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we present a novel air flow modeling strategy for deep wells that is suitable for real-time control of large-scale systems. We consider the mining ventilation control application, where specifically designed models are crucial for new automation strategies based on global system control and energy consumption optimization. Two different levels of complexity are proposed. Starting from a general model based on Navier-Stokes equations, we derive a 0-D, Bond Graph model. This mode...

Witrant, E.; Johansson, Karl Henrik

2008-01-01

207

Spectral modeling of radiation in combustion systems  

Science.gov (United States)

Radiation calculations are important in combustion due to the high temperatures encountered but has not been studied in sufficient detail in the case of turbulent flames. Radiation calculations for such problems require accurate, robust, and computationally efficient models for the solution of radiative transfer equation (RTE), and spectral properties of radiation. One more layer of complexity is added in predicting the overall heat transfer in turbulent combustion systems due to nonlinear interactions between turbulent fluctuations and radiation. The present work is aimed at the development of finite volume-based high-accuracy thermal radiation modeling, including spectral radiation properties in order to accurately capture turbulence-radiation interactions (TRI) and predict heat transfer in turbulent combustion systems correctly and efficiently. The turbulent fluctuations of temperature and chemical species concentrations have strong effects on spectral radiative intensities, and TRI create a closure problem when the governing partial differential equations are averaged. Recently, several approaches have been proposed to take TRI into account. Among these attempts the most promising approaches are the probability density function (PDF) methods, which can treat nonlinear coupling between turbulence and radiative emission exactly, i.e., "emission TRI". The basic idea of the PDF method is to treat physical variables as random variables and to solve the PDF transport equation stochastically. The actual reacting flow field is represented by a large number of discrete stochastic particles each carrying their own random variable values and evolving with time. The mean value of any function of those random variables, such as the chemical source term, can be evaluated exactly by taking the ensemble average of particles. The local emission term belongs to this class and thus, can be evaluated directly and exactly from particle ensembles. However, the local absorption term involves interactions between the local particle and energy emitted by all other particles and, hence, cannot be obtained from particle ensembles directly. To close the nonlinear coupling between turbulence and absorption, i.e., "absorption TRI", an optically thin fluctuation approximation can be applied to virtually all combustion problems and obtain acceptable accuracy. In the present study a composition-PDF method is applied, in which only the temperature and the species concentrations are treated as random variables. A closely coupled hybrid finite-volume/Monte Carlo scheme is adopted, in which the Monte Carlo method is used to solve the composition-PDF for chemical reactions and the finite volume method is used to solve for the flow field and radiation. Spherical harmonics method-based finite volume solvers (P-1 and P-3) are developed using the data structures of the high fidelity open-source code flow software OpenFOAM. Spectral radiative properties of the participating medium are modeled using full-spectrum k-distribution methods. Advancements of basic k-distribution methods are performed for nongray nonhomogeneous gas- and particulate-phase (soot, fuel droplets, ash, etc.) participating media using multi-scale and multi-group based approaches. These methods achieve close-to benchmark line-by-line (LBL) accuracy in strongly inhomogeneous media at a tiny fraction of LBL's computational cost. A portable spectral module is developed, which includes all the basic to advanced k-distribution methods along with the precompiled accurate and compact k-distribution databases. The P-1 /P-3 RTE solver coupled with the spectral module is used in conjunction with the combined Reynolds-averaged Navier-Stokes (RANS) and composition-PDF-based turbulence-chemistry solver to investigate TRI in multiphase turbulent combustion systems. The combustion solvers developed in this study is employed to simulate several turbulent jet flames, such as Sandia Flame D, and artificial nonsooting and sooting flames derived from Flame D. The effects of combustion chemi

Pal, Gopalendu

208

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, CO_2 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

1981-01-01

209

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...

210

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

A. Gallice

2011-10-01

211

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

212

The impact of diurnal variations of air traffic on contrail radiative forcing  

Directory of Open Access Journals (Sweden)

Full Text Available We combined high resolution aircraft flight data from the EU Fifth Framework Programme project AERO2k with analysis data from the ECMWF's integrated forecast system to calculate diurnally resolved 3-D contrail cover. We scaled the contrail cover in order to match observational data for the Bakan area (eastern-Atlantic/western-Europe.

We found that less than 40% of the global distance travelled by aircraft is due to flights during local night time. Yet, due to the cancellation of shortwave and longwave effects during daytime, night time flights contribute a disproportional 60% to the global annual mean forcing. Under clear sky conditions the night flights contribute even more disproportionally at 76%. There are pronounced regional variations in night flying and the associated radiative forcing. Over parts of the North Atlantic flight corridor 75% of air traffic and 84% of the forcing occurs during local night, whereas only 35% of flights are during local night in South-East Asia, yet these contribute 68% of the radiative forcing. In general, regions with a significant local contrail radiative forcing are also regions for which night time flights amount to less than half of the daily total of flights. Therefore, neglecting diurnal variations in air traffic/contrail cover by assuming a diurnal mean contrail cover can over-estimate the global mean radiative forcing by up to 30%.

N. Stuber

2007-06-01

213

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  

Energy Technology Data Exchange (ETDEWEB)

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 N, 36.6 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{sup -4} kW h/m{sup 2}, RMSE = 0.10 kW h/m{sup 2}, 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 estimate (MPE = -2.04%, MBE = -0.22 kW h/m{sup 2}, and RMSE = 0.59 kW h/m{sup 2}), 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. (author)

Maghrabi, A.H. [Institute of Astronomical and Geophysical Research, King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442 (Saudi Arabia)

2009-11-15

214

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 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.

2009-11-01

215

Radiative torques: Analytical Model and Basic Properties  

CERN Document Server

We attempt to get a physical insight into grain alignment processes by studying basic properties of radiative torques (RATs). For this purpose we consider a simple toy model of a helical grain that reproduces well the basic features of RATs. The model grain consists of a spheroidal body with a mirror attached at an angle to it. Being very simple, the model allows analytical description of RATs that act upon it. We show a good correspondence of RATs obtained for this model and those of irregular grains calculated by DDSCAT. Our analysis of the role of different torque components for grain alignment reveals that one of the three RAT components does not affect the alignment, but induces only for grain precession. The other two components provide a generic alignment with grain long axes perpendicular to the radiation direction, if the radiation dominates the grain precession, and perpendicular to magnetic field, otherwise. We study a self-similar scaling of RATs as a function of $\\lambda/a_{eff}$. We show that th...

Lazarian, Alex

2007-01-01

216

Models for the Development of Radiation Countermeasures  

Directory of Open Access Journals (Sweden)

Full Text Available Appropriate models are essential for making the transition from scientific discoveries to meaningful applications of the knowledge for human use. Acute as well as delayed effects of ionising radiation to the biological systems develop hierarchically starting from damage to the vital macromolecules up to the disturbances caused at the whole organism level. In vitro models like bacteria, yeast, various mammalian cells cultured as monolayers (2-D and spheroids (3-D as well as cells with specific genetic alterations have provided insight into the complex relationships between damage induction and various signal transduction pathways, allowing identification of molecular and sub-cellular targets vital to the fate of irradiated cells. On the other hand, in vivo models (multicellular whole organisms, ranging from simple worms to non-human primates, have been gainfully employed to evaluate efficacy as well as toxicity of potential countermeasure agents (molecules, combinations and formulated preparations facilitating their deployment in human subjects. This review provides a brief account of the efforts with various in vitro and in vivo models for understanding the biological basis of radiation damage as well as the development of radiation countermeasures, viz., protectors, mitigators and therapeutics.

Indracanti Prem Kumar

2011-03-01

217

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

1993-04-01

218

Radiation responses in air-, nitrous oxide-, and nitrogen-saturated mammalian cells  

International Nuclear Information System (INIS)

Characteristics of cellular radiation chemistry were studied for mammalian cells saturated with air, nitrous oxide, or nitrogen in the absence or presence of an OH-radical scavenger, for both low- and high-LET radiations. For clarity, the data for low-LET studies are presented separately in this paper, while the results for densely ionizing particle radiations will be discussed in a subsequent manuscript. Cell monolayers were grown in glass vessels and irradiated with 225-kVp X rays. The contribution of OH-radical action was reduced from about 55% in aerobic cells to about 20% in nitrogen-saturated cells. In nitrous oxide-saturated cells, the indirect effect attributable to OH. is about 35%. OH-radical-mediated lesions can therefore result in oxygen-independent as well as oxygen-dependent lesions. Our results show that the hydrated electron does not contribute significantly to radiolethality in anaerobic cells

1982-01-01

219

Mathematical model of an air-filled alpha stirling refrigerator  

Science.gov (United States)

This work develops a mathematical model for an alpha Stirling refrigerator with air as the working fluid and will be useful in optimizing the mechanical design of these machines. Two pistons cyclically compress and expand air while moving sinusoidally in separate chambers connected by a regenerator, thus creating a temperature difference across the system. A complete non-linear mathematical model of the machine, including air thermodynamics, and heat transfer from the walls, as well as heat transfer and fluid resistance in the regenerator, is developed. Non-dimensional groups are derived, and the mathematical model is numerically solved. The heat transfer and work are found for both chambers, and the coefficient of performance of each chamber is calculated. Important design parameters are varied and their effect on refrigerator performance determined. This sensitivity analysis, which shows what the significant parameters are, is a useful tool for the design of practical Stirling refrigeration systems.

McFarlane, Patrick; Semperlotti, Fabio; Sen, Mihir

2013-10-01

220

Radiative leptogenesis in minimal seesaw models  

Energy Technology Data Exchange (ETDEWEB)

In the framework of seesaw models with only two heavy Majorana neutrinos, nonzero leptonic asymmetries can be radiatively generated when exact heavy neutrino mass degeneracy (M{sub 1}=M{sub 2}=M) is imposed at a scale {lambda}{sub D}>M. For a specific case, we show that an acceptable value for the baryon asymmetry of the Universe can be obtained considering thermal leptogenesis.

Joaquim, F.R. [Dipartimento di Fisica ' G. Galilei' , Universita di Padova and INFN, Sezione di Padova, Via Marzolo, 8 - 1-35131 Padua (Italy)

2005-08-15

 
 
 
 
221

MODEL DINAMIK PENGENDALIAN PENCEMARAN AIR KALI SURABAYA  

Directory of Open Access Journals (Sweden)

Full Text Available The Surabaya River plays an important role as water supply of the Surabaya PDAM, irrigation, industry, transportation, and means of recreation. However, domestic, industrial, and agricultural waste that were discharged into the river stream polluted the Surabaya River and decreased the carrying capacity and assimilative capacity. Therefore, effort to monitor and control the Surabaya River water pollution need to be well organized and implemented. The aim of the research is to develop a model of water pollution control on Surabaya River region. The research was carried out based on field survey, in situ and laboratory sample examination, questionnaire, and expert judgment. Pollution control model developed in this study was built into three sub-models, namely: (1 ecology sub-model, (2 social sub-model, and (3 economy sub-model using powersim constructor 2.5 version. Pollution control scenarios were developed using prospective analysis. The results of water pollution parameters such as TSS, DO, BOD, COD, N-NO2, and the level of mercury (Hg were higher than the allowable class 1 standard. The sources of Surabaya River pollution mainly are domestic and industrial waste with total load of BOD, COD, and TSS are 55.49, 132.58, and 210.13 ton/day, respectively. According to water quality status, the Surabaya River is categorized as heavy polluted and the loading pollution need to be decreased. By using prospective analysis, there were five important factors that affect the future of the Surabaya River water pollution control, i.e.: (1 population growth and community awareness, (2 community perception, (3 implementation of regulations, (4 commitment/local government support, and (5 system and institutional capacity. There are three development scenarios, that are pessimistic, moderate and optimistic. The moderate and optimistic scenario are the realistic scenarios that occur in the future for Surabaya River water pollution control in considering of ecology, social and economy aspects.

Ita Djuwita

2011-08-01

222

Joint space-time geostatistical model for air quality surveillance  

Science.gov (United States)

Air pollution and peoples' generalized concern about air quality are, nowadays, considered to be a global problem. Although the introduction of rigid air pollution regulations has reduced pollution from industry and power stations, the growing number of cars on the road poses a new pollution problem. Considering the characteristics of the atmospheric circulation and also the residence times of certain pollutants in the atmosphere, a generalized and growing interest on air quality issues led to research intensification and publication of several articles with quite different levels of scientific depth. As most natural phenomena, air quality can be seen as a space-time process, where space-time relationships have usually quite different characteristics and levels of uncertainty. As a result, the simultaneous integration of space and time is not an easy task to perform. This problem is overcome by a variety of methodologies. The use of stochastic models and neural networks to characterize space-time dispersion of air quality is becoming a common practice. The main objective of this work is to produce an air quality model which allows forecasting critical concentration episodes of a certain pollutant by means of a hybrid approach, based on the combined use of neural network models and stochastic simulations. A stochastic simulation of the spatial component with a space-time trend model is proposed to characterize critical situations, taking into account data from the past and a space-time trend from the recent past. To identify near future critical episodes, predicted values from neural networks are used at each monitoring station. In this paper, we describe the design of a hybrid forecasting tool for ambient NO2 concentrations in Lisbon, Portugal.

Russo, A.; Soares, A.; Pereira, M. J.

2009-04-01

223

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

224

Numerical modelling of negative discharges in air with experimental validation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2011-01-01

225

Dynamic modeling of an air source heat pump water heater  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a dynamic simulation model to predict the performance of an air source heat pump water heater (ASHPWH). The mathematical model consists of submodels of the basic system components i.e. evaporator, condenser, compressor, and expansion valve. These submodels were built based on fundamental principles of heat transfer, thermodynamics, fluid mechanics, empirical relationships and manufacturer's data as necessary. The model simulation was carried out using MATLAB software. Refr...

2011-01-01

226

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

2006-02-01

227

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

1994-03-01

228

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)

2003-09-22

229

OpenAIRE Data Model Specification  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The OpenAIREplus web site will offer functionalities for administrators, anonymous and registered users to manage an Information Space of publications, together with their connections with funding projects (from the EC and national agencies) and research datasets. The aim of this document is to describe the conceived structure and semantics of this Information Space, i.e., the OpenAIREplus data model, by providing an abstract definition of its main entities and the relationships between them....

Manghi, Paolo; Mikulicic, Marko; Atzori, Claudio

2012-01-01

230

Introductory Tools for Radiative Transfer Models  

Science.gov (United States)

Satellite data are currently so voluminous that, despite their unprecedented quality and potential for scientific application, only a small fraction is analyzed due to two factors: researchers' computational constraints and a relatively small number of researchers actively utilizing the data. Ultimately it is hoped that the terabytes of unanalyzed data being archived can receive scientific scrutiny but this will require a popularization of the methods associated with the analysis. Since a large portion of complexity is associated with the proper implementation of the radiative transfer model, it is reasonable and appropriate to make the model as accessible as possible to general audiences. Unfortunately, the algorithmic and conceptual details that are necessary for state-of-the-art analysis also tend to frustrate the accessibility for those new to remote sensing. Several efforts have been made to have web- based radiative transfer calculations, and these are useful for limited calculations, but analysis of more than a few spectra requires the utilization of home- or server-based computing resources. We present a system that is designed to allow for easier access to radiative transfer models with implementation on a home computing platform in the hopes that this system can be utilized in and expanded upon in advanced high school and introductory college settings. This learning-by-doing process is aided through the use of several powerful tools. The first is a wikipedia-style introduction to the salient features of radiative transfer that references the seminal works in the field and refers to more complicated calculations and algorithms sparingly5. The second feature is a technical forum, commonly referred to as a tiki-wiki, that addresses technical and conceptual questions through public postings, private messages, and a ranked searching routine. Together, these tools may be able to facilitate greater interest in the field of remote sensing.

Feldman, D.; Kuai, L.; Natraj, V.; Yung, Y.

2006-12-01

231

Auroral Kilometric Radiation -Horseshoe Model and Experiment  

Science.gov (United States)

AKR is a powerful phenomenon of producing cyclotron maser emission from polar regions and it is common for many astrophysical sources with strong magnetic field, including the Earth. We claim that a horseshoe-shape distribution of electrons in momentum space is a drive for such emissions. This distribution forms when a beam of electrons moves into convergent magnetic field. We did theoretical modelling, numerical simulations and scaled laboratory experiment modelling formation of such a distribution and radiation from it by mechanism of cyclotron maser emission with perpendicular drive. The shape of the distribution has a good resemble with electron momentum distributions from several satellite observations data taken inside the source. Predicted frequency from theory and numerical simulations is in very good agreement with the experiment and the observations for the Earth's AKR. As with the observations, the radiation was found to come almost perpendicularly to the electrons' motion. The distribution proved to be unstable to cyclotron instability, providing a much higher growth rate then a loss cone distribution which is often used for modelling this radiation. Numerical simulations and theory were accurate in predicting the power of radiation and its polarisation for the experiment where a high power radiation from magnetically confined distribution was observed at a frequency just under the cyclotron frequency, being polarised in TE mode which corresponds to X-mode in auroral cavities. Addressing the recent observational results which discovered that the emission at a source comes out at a small angle to the perpendicular to the magnetic field/electron beam motion, in a direction slightly towards the opposite direction to that of the electrons motion, we checked that with our model, numerical simulations and the experiment. They all confirmed the direction of propagation at about 40 backward from the perpendicular direction with respect to the electrons motion. Our additional theoretical analysis showed that the backward propagation is a universal feature for this kind of emission and does not only happen for some particular range of parameters. The theory, simulations and experiment, all showing very good agreement with all the details of observations, strongly support the hypothesis that the horseshoe distribution drives AKR and similar emissions from astrophysical sources. We plan to apply this model forcyclotron emission also to extrasolar objects producing radio emission.

Vorgul, Irena; Kellet, Barry; Cairns, Robert; Bingham, Robert; Ronald, Kevin; Speirs, David; McConville, Sandra; Gillespie, Karen; Phelps, Alan; Helling, Christiane

2014-05-01

232

Modelling non-isothermal flow and air leakage in a steel reheating furnace  

Energy Technology Data Exchange (ETDEWEB)

This progress report will give a brief summary on the modeling of the steel reheating furnace at Rautaruukki Oy carried out in Spring 1997 (January - June), after the basic 3-D flow model for the industrial scale steel reheating fumace in 1996. The current report includes the following modelling tasks: (1) Improving the convergence of the basic flow models, (2) Non-isothermal flow model with convective heat transfer, (3) Non-isothermal flow models for air leakage at charge and discharge doors, (4) Preliminary radiative heat transfer models. A reliable gas flow pattern is very important for the modelling of the fumace heat transfer. Gas flow in principle dominates the heat transfer characteristics and the temperature distribution in the fumace. The previous 3-D gas model was preliminary, and the main objectives were to construct the basic flow model, test the model workability, and obtain approximate flow pattern. Air leakage into the reheating fumace takes place in the charge and discharge doors of the fumace during operation. It not only brings local and overall cooling in the fumace, but also may cause extra oxidation to the steel slab surfaces and thus increase surface scaling. Therefore, it is important to known how the leakage air is mixed with the combustion gases and where the air travels in the fumace. Radiative heat transfer plays very important role in the total heat transfer to the slabs in the fumace. Radiation heat transfer modeling is the final goal in this project. A lot of efforts have been made for improving the convergence in the computation, in order to obtain more reliable gas flow pattern and mixing behaviour. The model is very difficult to converge due to the high velocity difference from 3 sets of gas burners. Different scales of relaxation factors were tested, but no efficient factors were found. EXPERT system as well as the local relaxation near the burner regions could not give reasonable improvements in convergence. In addition to the on-line relaxation parameter changes, a new automatic relaxation tool SARAH provided in PHOENICS 2.2 was also used to speed the convergence. It gave some help, but did not solve the convergence problem completely. One useful hint proved from the SARAH test is that the relaxation factors for velocity components should be much higher than the ones suggested by the menu system, and much higher than the factors EXPERT gives. This helped the later manual tests which gave finally a reasonable set of factors. In the current report, good convergence were reached in all the models, with the optimised relaxation factors. Air leaked into the furnace at about room temperature with different thermophysical properties, especially the density and viscosity. This non-isothermal mixing with hot gases cannot be realistically modeled unless heat transfer is taken into account. Before the full radiation models are established, convective heat transfer was considered in the air leakage models. In the convective heat transfer models, the non-isothermal mixing behaviour of air with hot gases can almost be represented, because the total cooling due to radiative heat transfer in the furnace is not very high. At the same time, a convective heat transfer model was made, in order to check the flow pattern change due to heat transfer. In the models with convective heat transfer, a through model debugging was carried out in order to get correct and complete wall boundary conditions. After the air leakage tests, a complete radiative heat transfer model was constructed. In this model, complete wall temperature and radiation boundary conditions were established. Detailed division of slab upper/lower surfaces as well as for other solid surfaces with different temperatures were made. In the beginning, conflict of GRND3 non-equilibrium wall functions with the six-flux model was encountered. It always overflew during the model ending stage for result file writing. Debugging of different wall radiation patches and covals didn`t give any explanation. Checking carefully the result files, it was found th

Yang Yongxiang; Jokilaakso, A.

1997-12-31

233

Air  

…the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions.…

234

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

235

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

International Nuclear Information System (INIS)

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.

2011-01-01

236

Monte Carlo modeling of the MammoSite(Reg) treatments: Dose effects of air pockets  

Science.gov (United States)

In the treatment of early-stage breast cancer, MammoSiteRTM has been used as one of the partial breast irradiation techniques after breast-conserving surgery. The MammoSiteRTM applicator is a single catheter with an inflatable balloon at its distal end that can be placed in the resected cavity (tumor bed). The treatment is performed by delivering the Ir-192 high-dose-rate source through the center lumen of the catheter by a remote afterloader while the balloon is inflated in the tumor bed cavity. In the MammoSiteRTM treatment, it has been found that air pockets occasionally exist and can be seen and measured in CT images. Experiences have shown that about 90% of the patients have air pockets when imaged two days after the balloon placement. The criterion for the air pocket volume is less than or equal to 10% of the planning target volume in volume. The purpose of this study is to quantify dose errors occurring at the interface of the air pocket in MammoSiteRTM treatments with Monte Carlo calculations, so that the dosimetric effects from the air pocket can be fully understood. Modern brachytherapy treatment planning systems typically consider patient anatomy as a homogeneous water medium, and incorrectly model lateral and backscatter radiation during treatment delivery. Heterogeneities complicate the problem and may result in overdosage to the tissue located near the medium interface. This becomes a problem in MammoSiteRTM brachytherapy when air pocket appears during the treatment. The resulting percentage dose difference near the air-tissue interface is hypothesized to be greater than 10% when comparing Monte Carlo N-Particle (version 5) with current treatment planning systems. The specific aims for this study are: (1) Validate Monte Carlo N-Particle (Version 5) source modeling. (2) Develop phantom. (3) Calculate phantom doses with Monte Carlo N-Particle (Version 5) and investigate doses difference between thermoluminescent dosimeter measurement, treatment planning system, and Monte Carlo results. (4) Calculate dose differences for various treatment parameters. The results from thermoliminescent dosimeter phantom measurements proves that with correct geometric and source models, Monte Carlo method can be used to estimate homogeneity and heterogeneity doses in MammoSiteRTM treatment. The resulting dose differences at various points of interests in Monte Carlo calculations were presented and compared between different calculation methods. The air pocket doses were found to be underestimated by the treatment planning system. It was concluded that after correcting for inverse square law, the underestimation error from the treatment planning system will be less than +/- 2.0%, and +/- 3.5%, at the air pocket surface and air pocket planning target volume, respectively, when comparing Monte Carlo N-Particle (version 5) results. If the skin surface is located close to the air pocket, the underestimation effect at the air pocket surface and air pocket planning target volume doses becomes less because the air outside of the skin surface reduces the air pocket inhomogeneity effect. In order to maintain appropriate skin dose within tolerance, the skin surface criterion should be considered as the smallest thickness of the breast tissue located between the air pocket and the skin surface. The thickness should be at least 5 mm. In conclusion, the air pocket outside the balloon had less than 10% inhomogeneity effect based on the situations studied. It is recommended that at least an inverse square correction should be taken into consideration in order to relate clinical outcomes to actual delivered doses to the air pocket and surrounding tissues.

Huang, Yu-Huei Jessica

237

Modeling the performance of an aluminum-air cell  

Science.gov (United States)

A mathematical model for analysis and prediction of the performance of the aluminum-air cell has been developed. The model takes into account the kinetics of the anode, cathode, and parasitic reactions. Ohmic losses in the electrolyte and mass transfer are also taken into account. The model prediction of cell performance shows good agreement with experimental data. The mathematical model provides detailed information about cell performance for a wide range of operating and design parameters. For better cell performance, our model studies suggest the use of higher electrolyte flow rates, smaller cell gaps, higher conductivities, lower parasitic current densities and operation at moderate current density. From our analysis, we have determined that, in an aluminum air cell, only the activation and ohmic overpotential are important.

Yang, Shao Hua; Knickle, Harold

238

Joint action of external radiation and the products of air radiolysis. [X rays; ozone; nitrogenoxides; mice  

Energy Technology Data Exchange (ETDEWEB)

The mechanism of the combined action of ozone, nitrogen oxides, and ionizing radiation is an important aspect of the hygienic evaluation of a production environment. Chronic contact with various concentrations of chemical agents, as well as acute radiation injury are real hazards although the literature has not described the physiological and biochemical patterns of their harm to humans. B.F. Mazhorov devised an apparatus for air electrolysis which can approximate the effect of air radiolysis, and it was used to study the above hazards. Mice were subjected to 50 to 1000 rad from an x-ray instrument (TNKh-250), 60 min, 180 KV, 5 to 20 mA, focal distances 45 cm. The ozone and nitrogen oxide levels were measured iodometrically. The reaction to radiation was calculated in terms of mortality and life span, blood leucocytes, hemoglobin and its derivatives, and oxidative phosphoryllation by the spleen. The chemical agents had a radioprotective action most pronounced at high concentrations within the limits of the Dcl/sub 50///sub 30/ for the mice.

Golikov, V.Ya.; Karklinskaya, O.N.; Mikhalev, V.P.; Vorotyntsev, A.P.; Kotov, N.N.

1977-06-01

239

International Space Station Radiation Shielding Model Development  

Science.gov (United States)

The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.

Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.

2001-01-01

240

Air  

…Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions. Our long-term objective Cleaner air for everyone…

 
 
 
 
241

Air  

…Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of climate change * Strategic assessment of potential emissions * Long-term predictions. Our long-term objective Cleaner air for everyone… Related Searches: position statements

242

Guidelines for air quality dispersion models critical review and recommendations  

Energy Technology Data Exchange (ETDEWEB)

The need for guidelines for air quality dispersion models for regulatory purposes has long been recognized by the British Columbia Ministry of Water, Land and Air Protection. A critical review of the most recent draft guidelines was performed by SENES Consultants Limited, to evaluate their approach, completeness and content, as well as to provide a direction for revisions and completion of a final guideline document. Specifically, the authors reviewed how technical information is gathered and compared approaches used by other jurisdictions. They incorporated operational realities based on the historical application of models in British Columbia and presented options and recommendations for the development of the guidelines. It was found that although information was provided, in many instances no specific guidance was offered. The lack of an overall modelling philosophy for regulatory applications in British Columbia was recognized as the main weakness of the draft document. Two options were examined: a tiered modelling approach following United States Environmental Protection Agency (USEPA) guidance; and a British Columbia appropriate modelling approach based on a non-steady state Gaussian puff model developed by the Sigma Research Corporation for the California Air Resources Board (CALPUFF) model. It was recommended that specific guidelines be limited to technical aspects regarding which models should be used and under what circumstances. 14 refs., 2 tabs., 11 figs.

Hrebenyk, B.W.; Young, J.W.S.; Radonjic, Z.R. [SENES Consultants Ltd., Vancouver, BC (Canada)

2003-05-08

243

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

244

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

2008-02-01

245

QUEST FOR AN ADVANCED REGIONAL AIR QUALITY MODEL  

Science.gov (United States)

Organizations interested in advancing the science and technology of regional air quality modeling on the "grand challenge" scale have joined to form CAMRAQ. hey plan to leverage their research finds by collaborating on the development and evaluation of CMSs so ambitious in scope ...

246

Vehicle Transient Air Conditioning Analysis: Model Development & System Optimization Investigations.  

Science.gov (United States)

The National Renewable Energy Laboratory (NREL) has developed a transient air conditioning (A/C) system model using SINDA/FLUINT analysis software. It captures all the relevant physics of transient A/C system performance, including two phase flow effects ...

T. J. Hendricks

2001-01-01

247

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

248

Discontinuous Galerkin Method for the Air Pollution Model  

Directory of Open Access Journals (Sweden)

Full Text Available 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

2013-06-01

249

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...

250

Radiation damage of paper samples in in-air PIXE analysis  

Energy Technology Data Exchange (ETDEWEB)

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)

Matsuyama, S.; Endo, H.; Ishii, K.; Yamazaki, H.; Tokai, Y.; Sugimoto, A.; Yamamoto, K.; Satoh, T. [Department of Quantum Science and Energy Engineering, Tohoku University, Sendai, Miyagi (Japan); Orihara, H. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center

1999-07-01

251

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

252

A comparison between weighted sum of gray and spectral CK radiation models for heat transfer calculations in furnaces  

Energy Technology Data Exchange (ETDEWEB)

Coupled reactive fluid dynamics and radiation calculations are performed in air and oxy-fuel furnaces using two gas radiative property models. The first one is the weighted sum of gray gases model (WSGG) and the second one is the correlated-k (CK) method which is a spectral model based on the cumulative distribution function of the absorption coefficient inside a narrow band. The WSGG model, generally used in industrial configurations, is less time consuming than the CK model. However it is found that it over-predicts radiative fluxes by about 12 % in industrial furnaces. (authors) 27 refs.

El Ammouri, F.; Plessier, R.; Till, M.; Marie, B.; Djavdan, E. [Air Liquide Centre de Recherche Claude Delorme, 78 - Jouy-en-Josas (France)

1996-12-31

253

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study describes computational fluid dynamics (CFD) modeling of ventilated façade. Ventilated façades are normal façade but it has an extra channel between the concrete wall and the (double skin) façade. Several studies found in the literature are carried out with CFD simulations about the behavior of the thermodynamic phenomena of the double skin façades systems. These studies conclude that the presence of the air gap in the ventilated façade affects the temperature in the building...

Miguel Mora Pe?rez, Gonzalo Lo?pez Patin?o

2013-01-01

254

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)

2001-11-14

255

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

2013-05-30

256

Modelling of Air Bubble Rising in Water and Polymeric Solution  

Science.gov (United States)

This study investigates a Computational Fluid Dynamics (CFD) model for a single air bubble rising in water and xanthan gum solution. The bubble rise characteristics through the stagnant water and 0.05% xanthan gum solution in a vertical cylindrical column is modelled using the CFD code Fluent. Single air bubble rise dispersed into the continuous liquid phase has been considered and modelled for two different bubble sizes. Bubble velocity and vorticity magnitudes were captured through a surface-tracking technique i.e. Volume of Fluid (VOF) method by solving a single set of momentum equations and tracking the volume fraction of each fluid throughout the domain. The simulated results of the bubble flow contours at two different heights of the cylindrical column were validated by the experimental results and literature data. The model developed is capable of predicting the entire flow characteristics of different sizes of bubble inside the liquid column.

Hassan, N. M. S.; Khan, M. M. K.; Rasul, M. G.; Subaschandar, N.

2010-06-01

257

Improved air ventilation rate estimation based on a statistical model  

International Nuclear Information System (INIS)

A new approach to air ventilation rate estimation from CO measurement data is presented. The approach is based on a state-space dynamic statistical model, allowing for quick and efficient estimation. Underlying computations are based on Kalman filtering, whose practical software implementation is rather easy. The key property is the flexibility of the model, allowing various artificial regimens of CO level manipulation to be treated. The model is semi-parametric in nature and can efficiently handle time-varying ventilation rate. This is a major advantage, compared to some of the methods which are currently in practical use. After a formal introduction of the statistical model, its performance is demonstrated on real data from routine measurements. It is shown how the approach can be utilized in a more complex situation of major practical relevance, when time-varying air ventilation rate and radon entry rate are to be estimated simultaneously from concurrent radon and CO measurements

2004-07-02

258

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

1980-12-01

259

Radiation transport mearurements of 14-MeV neutrons in liquid air  

International Nuclear Information System (INIS)

The Stohler Tankexperiment is an experiment designed to measure the radiation field originating from a 14-MeV neutron source in liquid air. Measured neutron and gamma ray spectra are tabulated for source-detector distances between 55 cm (48 g/cm2) and 235 cm (204 g/cm2). The neutron spectra cover the energy range 20 keV to 18 MeV and the gamma ray spectra cover the energy range from 0.6 to 12 MeV. The experimental errors are discussed in detail. (orig.)

1976-01-01

260

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

 
 
 
 
261

Air travel and radiation risks - review of current knowledge; Flugreisen und Strahlenrisiken - eine aktuelle Uebersicht  

Energy Technology Data Exchange (ETDEWEB)

Aircrew and passengers are exposed to cosmic radiation, in particular when travelling routes close to the poles and in high altitudes. The paper reviews current radiation measurement and estimation approaches as well as the actual level of cosmic radiation that personnel and travellers receive and summarizes the available epidemiological evidence on health effects of cosmic radiation. On average, German aircrew is exposed to les than 5 mSv per annum, and even frequent travellers only rarely reach values above 1 mSv/year. Cohort studies among aircrew have found very little evidence for an increased incidence or mortality of radiation-associated cancers. Only malignant melanoma rates have consistently found to be increased among male aircrew. Socioeconomic and reproductive aspects are likely to contribute to the slightly elevated breast cancer risk of female aircrew. Cytogenetic studies have not yielded consistent results. Based on these data overall risk increases for cancer among occupationally exposed aircrew appear unlikely. This also applies to air travellers who are usually exposed to much lower radiation levels. Occasional air travel during pregnancy does not pose a significant radiation risk, but further considerations apply in this situation. The currently available studies are limited with regard to methodological issues and case numbers so that a continuation of cohort studies in several European countries is being planned. (orig.) [German] Sowohl Flugpersonal wie Flugreisende sind kosmischer Strahlung ausgesetzt, insbesondere wenn sie auf polnahen Routen und in grossen Flughoehen reisen. Die vorliegende Arbeit gibt einen aktuellen Ueberblick ueber Mess- und Schaetzverfahren sowie das Ausmass der kosmischen Strahlenexposition und fasst die derzeit bekannte epidemiologische Evidenz zu gesundheitlichen Aspekten der kosmischen Strahlenexposition zusammen. Die durchschnittliche jaehrliche Strahlenexposition beruflich exponierten Flugpersonals liegt in Deutschland unter 5 mSv, selbst regelmaessig Flugreisende erreichen nur selten Werte ueber 1 mSv. In Kohortenstudien bei Flugpersonal wurden kaum Hinweise auf erhoehte Inzidenz oder Mortalitaet strahlenassoziierter Tumore gefunden, konsistente Risikoerhoehungen wurden jedoch fuer das maligne Melanom bei Maennern berichtet. Ursachen fuer die leicht erhoehte Brustkrebsinzidenz des Flugpersonals werden auch in reproduktiven und soziooekonomischen Faktoren gesehen. Zytogenetische Untersuchungen auf strahlenassoziierte Veraenderungen ergeben bisher kein konsistentes Bild. Aufgrund der derzeit vorliegenden Ergebnisse ist das zusaetzliche Krebsrisiko fuer beruflich strahlenexponiertes Flugpersonal nicht deutlich erhoeht. Fuer Flugreisende ist aufgrund der niedrigeren Exposition eine Risikoerhoehung ebenfalls weitgehend auszuschliessen. Gelegentliche Flugreisen in der Schwangerschaft werden vor dem Hintergrund der epidemiologischen Daten ebenfalls als unbedenklich eingeschaetzt, aber hier spielen weitere Erwaegungen eine Rolle. Die bisher vorliegenden Studien weisen Einschraenkungen in Bezug auf methodische Vorgehensweisen und Fallzahlen auf, so dass in mehreren europaeischen Laendern eine Fortsetzung der Kohortenstudien bei Flugpersonal geplant sind. (orig.)

Zeeb, H. [Bielefeld Univ. (Germany). Fakultaet fuer Gesundheitswissenschaften; Blettner, M. [Mainz Univ. (Germany). Inst. fuer Medizinische Biometrie, Epidemiologie und Informatik

2004-07-01

262

Spatial distribution of emissions to air - the SPREAD model  

Energy Technology Data Exchange (ETDEWEB)

The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmark's obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously, a distribution on the 17x17 km EMEP grid has been set up and used in research projects combined with detailed distributions for a few sectors or sub-sectors e.g. a distribution for emissions from road traffic on 1x1 km resolution. SPREAD is developed to generate improved spatial emission data for e.g. air quality modelling in exposure studies. SPREAD includes emission distributions for each sector in the Danish inventory system; stationary combustion, mobile sources, fugitive emissions from fuels, industrial processes, solvents and other product use, agriculture and waste. This model enables generation of distributions for single sectors and for a number of sub-sectors and single sources as well. This report documents the methodologies in this first version of SPREAD and presents selected results. Further, a number of potential improvements for later versions of SPREAD are addressed and discussed. (Author)

Plejdrup, M.S.; Gyldenkaerne, S.

2011-04-15

263

Spatial distribution of emissions to air â?? the SPREAD model  

DEFF Research Database (Denmark)

The National Environmental Research Institute (NERI), Aarhus University, completes the annual national emission inventories for greenhouse gases and air pollutants according to Denmarkâ??s obligations under international conventions, e.g. the climate convention, UNFCCC and the convention on long-range transboundary air pollution, CLRTAP. NERI has developed a model to distribute emissions from the national emission inventories on a 1x1 km grid covering the Danish land and sea territory. The new spatial high resolution distribution model for emissions to air (SPREAD) has been developed according to the requirements for reporting of gridded emissions to CLRTAP. Spatial emission data is e.g. used as input for air quality modelling, which again serves as input for assessment and evaluation of health effects. For these purposes distributions with higher spatial resolution have been requested. Previously, a distribution on the 17x17 km EMEP grid has been set up and used in research projects combined with detailed distributions for a few sectors or sub-sectors e.g. a distribution for emissions from road traffic on 1x1 km resolution. SPREAD is developed to generate improved spatial emission data for e.g. air quality modelling in exposure studies. SPREAD includes emission distributions for each sector in the Danish inventory system; stationary combustion, mobile sources, fugitive emissions from fuels, industrial processes, solvents and other product use, agriculture and waste. This model enables generation of distributions for single sectors and for a number of sub-sectors and single sources as well. This report documents the methodologies in this first version of SPREAD and presents selected results. Further, a number of potential improvements for later versions of SPREAD are addressed and discussed.

Plejdrup, Marlene Schmidt; Gyldenkærne, Steen

2011-01-01

264

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

265

Helicopter air resonance modeling and suppression using active control  

Science.gov (United States)

A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. Using this mathematical model, a nominal configuration is selected with an air resonance instability throughout most of its flight envelope. A multivariable compensator is then designed using two swashplate inputs and a single-body roll rate measurement. The controller design is based on the linear quadratic Gaussian technique and the loop transfer recovery method. The controller is shown to suppress the air resonance instability throughout a wide range of helicopter loading conditions and forward flight speeds.

Takahashi, M. D.; Friedmann, P. P.

1991-01-01

266

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

267

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.

BaÌ?ckstroÌ?m, Daniel; Johansson, Robert

2014-01-01

268

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

1982-01-01

269

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 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

2005-12-01

270

Study of the Cherenkov radiation pulse duration of extensive air showers with the energy of more than 1015eV  

International Nuclear Information System (INIS)

Investigations into the shape of the Cherenkov radiation pulses of extensive air showers (EAS) with 1015 eV energy have been carried on at the Samarcand EAS facility using a new detector consisting of 12 photomultipliers. Pulse durations have been measured and depths of EAS maxima have been determined. A mean pulse duration at a distance of 200 m amounts to 8.6+-0.9 ns. New results agree well with experimental data obtained in Japan and don't contradict results of a model calculation according to the supercritical pomeron theory for a mixed chemical composition of the primary radiation

1985-07-01

271

Caenorhabditis elegans: a model to monitor bacterial air quality  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Low environmental air quality is a significant cause of mortality and morbidity and this question is now emerging as a main concern of governmental authorities. Airborne pollution results from the combination of chemicals, fine particles, and micro-organisms quantitatively or qualitatively dangerous for health or for the environment. Increasing regulations and limitations for outdoor air quality have been decreed in regards to chemicals and particles contrary to micro-organisms. Indeed, pertinent and reliable tests to evaluate this biohazard are scarce. In this work, our purpose was to evaluate the Caenorhaditis elegans killing test, a model considered as an equivalent to the mouse acute toxicity test in pharmaceutical industry, in order to monitor air bacterial quality. Findings The present study investigates the bacterial population in dust clouds generated during crop ship loading in harbor installations (Rouen harbor, Normandy, France. With a biocollector, airborne bacteria were impacted onto the surface of agar medium. After incubation, a replicate of the colonies on a fresh agar medium was done using a velvet. All the replicated colonies were pooled creating the "Total Air Sample". Meanwhile, all the colonies on the original plate were isolated. Among which, five representative bacterial strains were chosen. The virulence of these representatives was compared to that of the "Total Air Sample" using the Caenorhaditis elegans killing test. The survival kinetic of nematodes fed with the "Total Air Sample" is consistent with the kinetics obtained using the five different representatives strains. Conclusions Bacterial air quality can now be monitored in a one shot test using the Caenorhaditis elegans killing test.

Duclairoir Poc Cécile

2011-11-01

272

MODELS-3 COMMUNITY MULTISCALE AIR QUALITY (CMAQ) MODEL AEROSOL COMPONENT 1: MODEL DESCRIPTION  

Science.gov (United States)

The aerosol component of the Community Multiscale Air Quality (CMAQ) model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdis...

273

Considerations on the acoustic energy radiated by toothed gears. [model for calculating noise intensity  

Science.gov (United States)

A mechano-acoustic model is reported for calculating acoustic energy radiated by a working gear. According to this model, a gear is an acoustic coublet formed of the two wheels. The wheel teeth generate cylindrical acoustic waves while the front surfaces of the teeth behave like vibrating pistons. Theoretical results are checked experimentally and good agreement is obtained with open gears. The experiments show that the air noise effect is negligible as compared with the structural noise transmitted to the gear box.

Popinceanu, N. G.; Kremmer, I.

1974-01-01

274

Radiation transport in earth for neutron and gamma ray point sources above an air-ground interface  

Energy Technology Data Exchange (ETDEWEB)

Two-dimensional discrete ordinates methods were used to calculate the instantaneous dose rate in silicon and neutron and gamma ray fluences as a function of depth in earth from point sources at various heights (1.0, 61.3, and 731.5 meters) above an air--ground interface. The radiation incident on the earth's surface was transported through an earth-only and an earth--concrete model containing 0.9 meters of borated concrete beginning 0.5 meters below the earth's surface to obtain fluence distributions to a depth of 3.0 meters. The inclusion of borated concrete did not significantly reduce the total instantaneous dose rate in silicon and, in all cases, the secondary gamma ray fluence and corresponding dose are substantially larger than the primary neutron fluence and corresponding dose for depths greater than 0.6 meter. 4 figures, 4 tables.

Lillie, R.A.; Santoro, R.T.

1979-03-01

275

Optimized broad energy group structures for radiation transport in air and in LWR-shields  

International Nuclear Information System (INIS)

Basic ideas of the automatic group collapsing scheme AGRUKO are briefly described. The errors introduced by the collapsing process are controlled by criteria, which are constructed by the sensitivity profiles and the required target accuracies of the specific shielding type configurations. The group widths are optimized to reduce the calculation time with respect to the fine group calculations. Optimized group structures were generated for two rather different shielding benchmarks: Neutron and gamma transport in a LWR-shield and in air using a fusion source respectively. In the case of the LWR-shield the 100/20 groups EURLIB-3 structure was collapsed to 45/16 and 15/5 groups. In the case of the ''air'' problem the original 22/18 groups were collapsed to 4/8 groups. The accuracies achieved were in general within the required accuracies for the targets thermal flux (activation), radiation damage, radiation heating and dose rates. Because the broad group structures were optimized in view of basic physical and numerical principles, they are nearly free from arbitrary assumptions as constant lethargy width e.g. Therefore they may be recommended for further use in the field of more complex transport calculations or cross section adjustment procedures. (Auth.)

1981-01-01

276

Comparison of the performance of net radiation calculation models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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,...

Kjaersgaard, Jeppe Hvelplund; Cuenca, Richard Henry; Marti?nez-cob, Antonio; Gavila?n Zafra, Pedro; Plauborg, F. L.; Mollerup, M.; Hansen, S.

2009-01-01

277

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

1989-01-01

278

Model of quantum noise of shadow radiation images  

International Nuclear Information System (INIS)

Correlation characteristics of quantum noise on the shadow radiation image (RI) of the object under nondestructive testing are studied. Mathematical model of RI occasional distortions is derived. The model takes into account the parameters of object under testing and of radiation beam by radiation quanta flux density. The results obtained can be used as a component in the process of investigation of various radiation testing systems

2000-01-01

279

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

280

Heat transfer in Rockwool modelling and method of measurement. Modelling radiative heat transfer in fibrous materials  

Energy Technology Data Exchange (ETDEWEB)

Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For lager thickness dimensions the resulting heat transfer through the fibrous material will be relatively small, which means that a relatively small increase in heat loss by convection may counterbalance part of the savings achieved by increasing the thickness. (au) 39 refs.

Dyrboel, Susanne

1998-05-01

 
 
 
 
281

Air  

…Strategy in England and Wales. Policy/position statements Click on the links below to view the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of…

282

Air  

…Strategy in England and Wales. Policy/position statements Click on the links below to view the position statements on the following: * Environmental taxation * Air quality * Reducing the environmental impacts of road and air transport. Key environmental problems * Global warming and predicted effects of… Related Searches: position statements

283

Air  

…regulating the release of pollutants into air from over 2000 of the larger or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the Highways Agency and other organisations to deliver the Government??s Air Quality…

284

Air  

Air Environment Agency??s roles & responsibilities We play a major role by regulating the release of pollutants into air from over 2000 of the larger or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the… Related Searches: position statements

285

Recent advances in modelling diffuse radiation  

Energy Technology Data Exchange (ETDEWEB)

Boland et al (2001) developed a validated model for Australian conditions, using a logistic function instead of piecewise linear or simple nonlinear functions. Recently, Jacovides et al (2006) have verified that this model performs well for locations in Cyprus. Their analysis includes using moving average techniques to demonstrate the form of the relationship, which corresponds well to a logistic relationship. We have made significant advances in both the intuitive and theoretical justification of the use of the logistic function. In the theoretical development of the model utilising advanced non-parametric statistical methods. We have also constructed a method of identifying values that are likely to be erroneous. Using quadratic programming, we can eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. Additionally, this is a first step in identifying the means for developing a generic model for estimating diffuse from global and other predictors (see Boland and Ridley 2007). Our more recent investigations focus on examining the effects of adding additional explanatory variables to enhance the predictability of the model. Examples for Australian and other locations will be presented. (orig.)

Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, Univ. of South Australia, Mawson Lakes, SA (Australia)

2008-07-01

286

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

287

Guidelines and Technical Information Provided by the US Federal Aviation Administration to Promote Radiation Safety for Air Carrier Crew Members  

International Nuclear Information System (INIS)

The Federal Aviation Administration has provided instructional material on radiation exposure during air travel, supported research on radiation effects, and developed computer programs (CARI) for estimating the galactic radiation in the atmosphere. Based on a recent version of CARI, estimates are presented of effective dose rates of galactic radiation and the percentage contributions by its components, for the years 1958 through 1997, at various altitudes both at the equator and at a high latitude. Also presented are the effective doses of galactic radiation received on a variety of US domestic and transoceanic flights (flight doses). Incorporating flight doses, estimates were made of the total annual doses received by aircrew members from occupational plus non-occupational natural radiation sources. Annual doses to crew members, on and off the job, ranged from almost identical to about twice the average annual effective dose of natural background radiation received by a member of the US population. (author)

1998-07-01

288

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 3549â??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

289

Convection and thermal radiation analytical models applicable to a nuclear waste repository room  

International Nuclear Information System (INIS)

Time-dependent temperature distributions in a deep geologic nuclear waste repository have a direct impact on the physical integrity of the emplaced canisters and on the design of retrievability options. This report (1) identifies the thermodynamic properties and physical parameters of three convection regimes - forced, natural, and mixed; (2) defines the convection correlations applicable to calculating heat flow in a ventilated (forced-air) and in a nonventilated nuclear waste repository room; and (3) delineates a computer code that (a) computes and compares the floor-to-ceiling heat flow by convection and radiation, and (b) determines the nonlinear equivalent conductivity table for a repository room. (The tables permit the use of the ADINAT code to model surface-to-surface radiation and the TRUMP code to employ two different emissivity properties when modeling radiation exchange between the surface of two different materials.) The analysis shows that thermal radiation dominates heat flow modes in a nuclear waste repository room

1979-01-01

290

Monitoring of radiation fields in a waste tank model: Virtual radiation dosimetry  

International Nuclear Information System (INIS)

The University of Florida (UF) has developed a coupled radiation computation and three-dimensional modeling simulation code package. This package combines the Deneb Robotics' IGRIP three-dimensional solid modeling robotic simulation code with the UF developed VRF (Virtual Radiation Field) Monte Carlo based radiation computation code. The code package allows simulated radiation dose monitors to be placed anywhere on simulated robotic equipment to record the radiation doses which would be sustained when carrying out tasks in radiation environments. Comparison with measured values in the Hanford Waste Tank C-106 shows excellent results. The code shows promise of serving as a major tool in the design and operation of robotic equipment in radiation environments to ensure freedom from radiation caused failure

1995-09-03

291

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

292

Experimental analysis of airtightness and estimation of building air infiltration using two different single zone air infiltration models  

Directory of Open Access Journals (Sweden)

Full Text Available Building air leakage can contribute significantly to the energy consumption of a building. This paper presents the airtightness performance of a campus building located in Ontario, Canada. The air leakage rate through the building envelope was measured under stilted depressurization conditions following the ASTM E-779 standardized test method. With this test derived empirical leakage flow co-efficient and leakage flow exponent measures, the air infiltration rate for the building under varying wind and outside temperature conditions was calculated using two different single zone air infiltration models – the Lawrence Berkeley Laboratory model and the Alberta Air Infiltration model thus also allowing for a comparison of the results between the two mathematical models.

Tijo Joseph, Animesh Dutta

2014-01-01

293

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

294

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

295

Period adding cascades: experiment and modeling in air bubbling.  

Science.gov (United States)

Period adding cascades have been observed experimentally/numerically in the dynamics of neurons and pancreatic cells, lasers, electric circuits, chemical reactions, oceanic internal waves, and also in air bubbling. We show that the period adding cascades appearing in bubbling from a nozzle submerged in a viscous liquid can be reproduced by a simple model, based on some hydrodynamical principles, dealing with the time evolution of two variables, bubble position and pressure of the air chamber, through a system of differential equations with a rule of detachment based on force balance. The model further reduces to an iterating one-dimensional map giving the pressures at the detachments, where time between bubbles come out as an observable of the dynamics. The model has not only good agreement with experimental data, but is also able to predict the influence of the main parameters involved, like the length of the hose connecting the air supplier with the needle, the needle radius and the needle length. PMID:22463011

Pereira, Felipe Augusto Cardoso; Colli, Eduardo; Sartorelli, José Carlos

2012-03-01

296

Models for the prediction of room air distribution  

Energy Technology Data Exchange (ETDEWEB)

The paper describes work on simplified design methods made in connection with the International Energy Agency programme ''Air flow pattern within buildings'', Annex 20, subtask 1. It is shown that simplified models are able to indicate design values as the maximum velocity in the occupied zone and penetration depth of a non-isothermal jet in a room. The design according to throw of an isothermal jet is a fully developed method which has a sufficient level of accuracy when it is used in regular rooms. Models for prediction of the maximum velocity in the occupied zone and penetration depth of non-isothermal jets need further development. The possibility of Computional Fluid Dynamics (CFC) is evaluated and it is compared with simplified models. It is shown that the CFD method is especially useful because it gives the distribution of the variables as well as th design values. The CFD method can also predict variables which are time consuming to measure by full scale experiments. The CFD method is especially useful for the prediction of air distribution in large enclosures with complicated geometry and different sources for the air movement. (AB) (15 refs.).

Nielsen, P.V.

1991-12-01

297

A simplified calibrated model for estimating daily global solar radiation in Madinah, Saudi Arabia  

Science.gov (United States)

Solar radiation is the most important parameter in defining the energy budget at the surface thereby influencing the hydroclimate. Several empirical models based on air temperature are developed and used in several decision-making needs such as agriculture and energy sector. However, a calibration against direct observations is a priori for implementing such models. A calibrated model is developed for Saudi Arabia (Madinah) based on observations during 2007-2011. The model is used to estimate daily solar radiation and results show a correlation coefficient of 0.94. The calibrated model outperforms the uncalibrated model available for this location. To increase the confidence, the calibrated model is also compared with a simple artificial neural network.

Benghanem, M.; Mellit, A.

2014-01-01

298

Modeling and comparative thermal performance of ground air collector and earth air heat exchanger for heating of greenhouse  

Energy Technology Data Exchange (ETDEWEB)

The potential of using the stored thermal energy of ground for space heating has been investigated with the help of two buried pipe systems, i.e., ground air collector and earth air heat exchanger, integrated with the greenhouse located in the premises of Indian Institute of Technology, Delhi, India. The total length of the buried pipes in both the arrangements was kept same for making a comparative study. A complete numerical model has been developed to predict and compare their thermal performance for choosing a suitable heating method in the composite climate of India. Experiments were conducted extensively during winter period from November 2002 to March 2003, but the model was validated against the clear and sunny days. Performance of these two arrangements was compared in terms of thermal load leveling and total heating potential. Temperatures of greenhouse air with ground air collector were observed to be 2-3 {sup o}C higher than those with earth air heat exchanger. The temperature fluctuations of greenhouse air were also less when operated with ground air collector as compared to earth air heat exchanger. Predicted and computed values of greenhouse air temperatures in both the systems exhibited fair agreement. Finally ground air collector was chosen as a suitable option for heating of greenhouse in the above climate. (Author)

Ghosal, M.K.; Tiwari, G.N.; Das, D.K.; Pandey, K.P. [Indian Inst. of Technology, Delhi (India). Centre for Energy Studies

2005-06-01

299

Integrable Models of Interaction of Matter with Radiation  

Directory of Open Access Journals (Sweden)

Full Text Available The simplified models of interaction of charged matter with resonance modes of radiation generalizing the well-known Jaynes-Cummings and Dicke models are considered. It is found that these new models are integrable for arbitrary numbers of dipole sources and resonance modes of the radiation field. The problem of explicit diagonalisation of corresponding Hamiltonians is discussed.

Vladimir I. Inozemtsev

2006-10-01

300

Development of IIT air quality model for industrial use  

Energy Technology Data Exchange (ETDEWEB)

In the present study a mathematical model named UT Air quality (IITAQ) model has been developed which essentially retains all the desired features of a Gaussian model and at the same time overcomes most of the disadvantages associated with these Gaussian models. The proposed model is a numerical box model which incorporates sophistication with better or improved parameterization of the physical processes in the Atmospheric Boundary Layer and at the same time avoids the disadvantages of 3-D numerical models with detailed physics of ABL. The model uses the more realistic and easily adoptable input parameters. The estimation of these and model formulation have been discussed at length for the elevated source during all kinds of stability conditions. The main parameters namely wind and eddy diffusitivity profiles and dispersion coefficient make extensive use of Monin-Obukhov similarity theory. The model also incorporates latest formulation of plume rise and plume penetration. The estimated hourly Ground Level Concentration (GLC) have been compared with SF{sub 6} tracer diffusion experiments. The validation shows that the estimated concentration from IITAQ model are in good agreement with the observed values. The various statistical parameters have been estimated to truly assess the model performance.

Mohan, M. [Indian Institute of Technology, New Delhi (India); Siddiqui, T.A. [Engineers India Limited, Guragaon (India)

1996-12-31

 
 
 
 
301

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

302

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.

2009-07-01

303

AIR INGRESS ANALYSIS: PART 2 – 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

2011-01-01

304

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

2010-01-01

305

A biophysical model of radiation induced mutagenesis.  

Czech Academy of Sciences Publication Activity Database

. Vol. Intensive Course. Brno : KIRAMO, 1995 - (Kozubek, S.; Horneck, G.), s. 195-198[Radiation Biology and its Application in Space Research, Mutation Induction by Ionizing Radiation. Nedv?dice (CZ), 10.11.1994-12.11.1994

Kozubek, Stanislav

306

Bayesian extreme modeling for non-stationary air quality data  

Science.gov (United States)

The aim of this paper is to model the non-stationary Generalized Extreme Value distribution with a focus on Bayesian approach. The location parameter is expressed in terms of linear trend over the time period while constant for both scale and shape parameters. This study also explores the informative and Jeffrey's prior towards the efficiency of the estimating procedure. Root Mean Square Error is then use for choosing the best prior. Metropolis Hasting for extreme algorithm will also briefly explained in this study. The model is applied to the air quality data for Johor state.

Mohd Amin, Nor Azrita; Adam, Mohd Bakri; Ibrahim, Noor Akma; Aris, Ahmad Zaharin

2013-09-01

307

Meterorological and air quality models for urban areas  

Energy Technology Data Exchange (ETDEWEB)

This book, based on the selected presentations given at the COST728 workshop, is concerned with the following main topics/chapters: 1. Urban morphology and databases, 2. Parameterisations of urban canopy, 3. Strategy for urbanization of different types of models, 4. Evaluation and city case studies / field studies. The chapters were concerned with dynamic (on wind and turbulent) and thermal effects (on temperature and energy in general). The final chapter of this volume summarizes the discussion and conclusions from the four main topics and provides recommendations and future requirements. The book is oriented towards numerical weather prediction and air quality modelling communities. (orig.)

Baklanov, Alexander; Alexander, Mahura [Danish Meteorological Institute, Copenhagen (Denmark); Grimmond, C.S.B. [King' s College London (United Kingdom). Dept. Geography Strand; Athanassiadou, Maria (eds.) [Met Office, Exeter (United Kingdom)

2009-07-01

308

A model for calculating room air and surface tritium concentrations  

International Nuclear Information System (INIS)

A mathematical model and the resultant analytical solutions for calculation of transient tritium concentrations in room air and in solid surfaces are presented. Although more elaborate models exist for describing the behaviour of tritium released into enclosures, a simpler approach was considered adequate for a preliminary assessment of situations arising at JET. A comparison to experimental data and several cases of interest are also presented. These preliminary checks have confirmed that the basic approach is sound. Further checks and refinement may be required to cover the full range of practical situations. (author)

1988-01-01

309

Potential Models for Radiative Rare B Decays  

CERN Document Server

We compute the branching ratios for the radiative rare decays of B into K-Meson states and compare them to the experimentally determined branching ratio for inclusive decay b -> s gamma using non relativistic quark model, and form factor definitions consistent with HQET covariant trace formalism. Such calculations necessarily involve a potential model. In order to test the sensitivity of calculations to potential models we have used three different potentials, namely linear potential, screening confining potential and heavy quark potential as it stands in QCD.We find the branching ratios relative to the inclusive b ->s gamma decay to be (16.07\\pm 5.2)% for B -> K^* (892)gamma and (7.25\\pm 3.2)% for B -> K_2^* (1430)gamma for linear potential. In the case of the screening confining potential these values are (19.75\\pm 5.3)% and (4.74\\pm 1.2)% while those for the heavy quark potential are (11.18\\pm 4.6)% and (5.09\\pm 2.7)% respectively. All these values are consistent with the corresponding present CLEO experim...

Ahmad, S

2002-01-01

310

Estimation of Global Solar Radiation in Rwanda Using Empirical Models  

Directory of Open Access Journals (Sweden)

Full Text Available 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 square regression analysis. These coefficients were then used for the estimation of solar radiation in other places of Rwanda where measures of solar radiation do not exist but sunshine records are available.

B. Safari

2009-01-01

311

Experimental synergy combining lidar measurements so as to optically characterize aerosols: applications to air quality and radiative forcing  

International Nuclear Information System (INIS)

The work carried out in this study is devoted to a better understanding of the evolution of aerosol physical, chemical and optical properties for urban pollution aerosols, dust and biomass burning particles. It mainly concerns the complex refractive index and the single-scattering albedo. Such a characterisation is indeed necessary so as to fulfil the requirements of scientific and societal air quality and global climate evolution questions. Our study is based on a synergy between different measurements platforms: ground-based or airborne measurements, together with active and passive remote sensing observations. Lidar in particular turns out to be an essential tool in order to assess horizontal and vertical variability of aerosol micro-physical and optical properties in the atmospheric boundary layer, but also in the residual layer, as well as in layers transported from the boundary layer to the free troposphere. The original methodology we developed highlights the importance of the geographical origin, the impact of aging and dynamical processes in the evolution of structural, optical and hygroscopic aerosol features. The related accurate determination of the properties in each aerosol layer is required for radiative fluxes and heating rates calculations in the atmospheric column. The radiative impact of both dust particles and biomass burning aerosols observed over the region of Niamey (Niger) was thus assessed during the dry season. These results reveal the need of a better characterisation of those significant aerosol properties for each layer in models. (author)

2008-01-01

312

Description of a digital simulation program for modelling tactical anti-radiation weapons  

Energy Technology Data Exchange (ETDEWEB)

A general description is given of the computer program which simulates the performance of an anti-radiation homing weapon taking into account the properties of the seeker, assumed to be body-referenced, and the air vehicle. For the purpose of illustration, sample calculations have assumed a minidrone as the air vehicle, although the simulation has a wide range of applications to a variety of platforms. The program can simulate terminal homing in the situations where multiple, co-channel CW emitters are deployed. The three constituent simulation blocks (signal in space, seeker, and tactical vehicle) are discussed in detail, as well as models for sensor errors and wind effects.

Sorrentino, C.M.; Damato, R.

1983-03-01

313

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

1987-12-01

314

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

1986-01-01

315

Radiation safety of the helicopter air crow-liquidators of the Chernobyl NPP accident  

International Nuclear Information System (INIS)

Three aspects of the radiation safety of the helicopter air crew who took part in the elimination of the Chernobyl NPP accident after-effects during the period from the 27-th of April to July 1986 were considered: dosimetry, physical protection and radioprotector use. 1125 subjects from the flight and engineer personnel were irradiated: 6%-2.5 mSv and more, 32%-2.1-2.5 mSv and about 60% - up to 2.0 mSv. It is stated that the use of physical protection (local screening of a pilot seat and use of special antiradiation belts) makes irradiation doe 2-3 times less. In the intense conditions of flight activity the pilots preferred the radioprotector adrenaline to cystamin. Alimentary aids in the earlier and later periods after the accident influenced favourably somatic and psychic states. 16 refs.; 1 tab

1992-01-01

316

Samaa : A Software For Air Pollution Modelling and Analysis Activities  

Science.gov (United States)

In order to better understand the qualitative and quantitative evolution of air pollu- tion in cities and their surroundings, ACRI-st has designed and developed, jointly with two French air surveillance networks, an integrated application for air pollution modelling. This simulator, called Samaa, enables testing the impact on pollution of different emission scenarios under a number of meteorological conditions. Samaa is a platform with a user-friendly interface for scenario management, including an emission module, and a GIS-based results viewing module, that may in turn be interfaced with a meteorological and a chemistry/dispersion module (or a dispersion module). The meteorological module is processed first, before any other air pollution module of the simulator. It supplies the meteorological files that will then be used by the emis- sion module and subsequently by the dispersion and chemical modules. This module calculates wind and temperature fields, as well as different meteorological parameters. The AIREMIS emission module was designed to calculate the hourly emissions of seven primary pollutants for each emission sector (transport, industry, heating and natural environment). The GIS, integrated in the emission module, executes two main tasks : - preparation of the emission data sets that the modelling system will process - results viewing for all the different calculation modules (emission, wind and concen- tration maps). The chemistry/dispersion and the dispersion modules enable reactive and non reac- tive pollutants simulation in urban and sub-urban areas. They are interfaced with the other system element to allow simulation of pollutants concentration derived from non chemical or photochemical reactions. Samaa has been validated on two 3-day simulations : the first one was dedicated to evaluate the "chemical processing" of the simulator, and the second one to the "dis- persion processing". The results have proven the strength and the robustness of the system that is however very dependent on the input data. It has now been deployed on two French cities (Nantes and Clermont-Ferrand) where the air quality survey networks use it for air quality management and engineering 1 studies. Thanks to its flexibility, the emission module of SAMAA is presently under implementation on the city of Bogota (Colombia). Examples of application of Samaa will be presented during the conference. 2

Gueguen, C.; Mangin, A.; Sanchez, O.

317

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.

2012-06-01

318

76 FR 62605 - Airworthiness Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes With Supplemental Type...  

Science.gov (United States)

...2120-AA64 Airworthiness Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes...Federal Register. That AD applies to Viking Air Limited Model DHC-3 (Otter) airplanes...the airspeed indicator accordingly for Viking Air Limited Model DHC-3 (Otter)...

2011-10-11

319

A Multi-layer Radiation Model for Urban Neighbourhoods with Trees  

Science.gov (United States)

A neighbourhood-scale multi-layer urban canopy model of shortwave and longwave radiation exchange that explicitly includes the radiative effects of tall vegetation (trees) is presented. Tree foliage is permitted both between and above buildings, and mutual shading, emission and reflection between buildings and trees are included. The basic geometry is a two-dimensional canyon with leaf area density profiles and probabilistic variation of building height. Furthermore, the model accounts for three-dimensional path lengths through the foliage. Ray tracing determines the receipt of direct shortwave irradiance by building and foliage elements. View factors for longwave and shortwave diffuse radiation exchange are computed once at the start of the simulation using a Monte Carlo ray tracing approach; for subsequent model timesteps, matrix inversion rapidly solves infinite reflections and interception of emitted longwave between all elements. The model is designed to simulate any combination of shortwave and longwave radiation frequency bands, and to be portable to any neighbourhood-scale urban canopy geometry based on the urban canyon. Additionally, the model is sufficiently flexible to represent forest and forest-clearing scenarios. Model sensitivity tests demonstrate the model is robust and computationally feasible, and highlight the importance of vertical resolution to the performance of urban canopy radiation models. Full model evaluation is limited by the paucity of within-canyon radiation measurements in urban neighbourhoods with trees. Where appropriate model components are tested against analytic relations and results from an independent urban radiation transfer model. Furthermore, system response tests demonstrate the ability of the model to realistically distribute shortwave radiation among urban elements as a function of built form, solar angle and tree foliage height, density and clumping. Separate modelling of photosynthetically-active and near-infrared shortwave bands is shown to be important in some cases. Increased canyon height-to-width ratio and/or tree cover diminishes the net longwave radiation loss of individual canyon elements (e.g., floor, walls), but, notably, has little effect on the net longwave loss of the whole urban canopy. When combined with parametrizations for the impacts of trees on airflow and hydrological processes in the urban surface layer, the new radiation model extends the applicability of urban canopy models and permits more robust assessment of trees as tools to manage urban climate, air quality, human comfort and building energy loads.

Krayenhoff, E. S.; Christen, A.; Martilli, A.; Oke, T. R.

2014-04-01

320

A simple model for calculating air pollution within street canyons  

Science.gov (United States)

This paper introduces the Semi-Empirical Urban Street (SEUS) model. SEUS is a simple mathematical model based on the scaling of air pollution concentration inside street canyons employing the emission rate, the width of the canyon, the dispersive velocity scale and the background concentration. Dispersive velocity scale depends on turbulent motions related to wind and traffic. The parameterisations of these turbulent motions include two dimensionless empirical parameters. Functional forms of these parameters have been obtained from full scale data measured in street canyons at four European cities. The sensitivity of SEUS model is studied analytically. Results show that relative errors in the evaluation of the two dimensionless empirical parameters have less influence on model uncertainties than uncertainties in other input variables. The model estimates NO2 concentrations using a simple photochemistry scheme. SEUS is applied to estimate NOx and NO2 hourly concentrations in an irregular and busy street canyon in the city of Buenos Aires. The statistical evaluation of results shows that there is a good agreement between estimated and observed hourly concentrations (e.g. fractional bias are ?10.3% for NOx and +7.8% for NO2). The agreement between the estimated and observed values has also been analysed in terms of its dependence on wind speed and direction. The model shows a better performance for wind speeds >2 m s?1 than for lower wind speeds and for leeward situations than for others. No significant discrepancies have been found between the results of the proposed model and that of a widely used operational dispersion model (OSPM), both using the same input information.

Venegas, Laura E.; Mazzeo, Nicolás A.; Dezzutti, Mariana C.

2014-04-01

 
 
 
 
321

Gamma radiation exposure of air crew in Tehran-Bandarabbas flights  

International Nuclear Information System (INIS)

Different researches have been performed on natural exposure of cosmic rays and their effects on the human health. Monitoring of cosmic derived gamma ray exposure of air crews and passengers is the subject of the current study. In this paper, the control able variations of the cosmic ray flux in the atmosphere and the cosmic radiation exposure at flight altitudes will be discussed. For this study, the exposure rates to gamma ray, in an energy range of 50 keV-1.5 MeV, for the Tehran-Bandarabbas air flights have been measured. The results show that the maximum dose rate at 3000 ft (about 9 km) is 15-20 times higher than on the ground base. Also, the dose rate for this pathway is about 1.87?Sv/h which for 500 hours flights per year it is estimatal to be 935?Sv. This number is less than human permissible dose rate of 1 mSv/year.

2011-01-01

322

Predictive model of radiative neutrino masses  

Science.gov (United States)

We present a simple and predictive model of radiative neutrino masses. It is a special case of the Zee model which introduces two Higgs doublets and a charged singlet. We impose a family-dependent Z4 symmetry acting on the leptons, which reduces the number of parameters describing neutrino oscillations to four. A variety of predictions follow: the hierarchy of neutrino masses must be inverted; the lightest neutrino mass is extremely small and calculable; one of the neutrino mixing angles is determined in terms of the other two; the phase parameters take CP-conserving values with ?CP=?; and the effective mass in neutrinoless double beta decay lies in a narrow range, m??=(17.6-18.5) meV. The ratio of vacuum expectation values of the two Higgs doublets, tan?, is determined to be either 1.9 or 0.19 from neutrino oscillation data. Flavor-conserving and flavor-changing couplings of the Higgs doublets are also determined from neutrino data. The nonstandard neutral Higgs bosons, if they are moderately heavy, would decay dominantly into ? and ? with prescribed branching ratios. Observable rates for the decays ? ?e? and ??3? are predicted if these scalars have masses in the range of 150-500 GeV.

Babu, K. S.; Julio, J.

2014-03-01

323

Sensitivity analysis of thermal predictions to the modeling of direct solar radiation entering a zone  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Because of high computational costs of computational fluid dynamics multi-zone energy simulation is currently appraised. Yet, the use of empirical correlations to predict interior convective heat transfer (CHT) limits the reliability of building comfort and energy analysis. As most of these convection algorithms depend, partially, on the temperature difference between the concerned surface and the air, the influence of the modeling of incoming direct solar radiation is studied. Simulations of...

2009-01-01

324

Testing models of new physics with UHE air shower observations  

CERN Multimedia

Several air shower observatories have established that the number of muons produced in UHE air showers is significantly larger than that predicted by models. We argue that the only solution to this muon deficit, compatible with the observed Xmax distributions, is to reduce the transfer of energy from the hadronic shower into the EM shower, by reducing the production or decay of pi0s. We present four different models of new physics, each with a theoretical rationale, which can accomplish this. One has a pure proton composition and three have mixed composition. Two entail new particle physics and suppress pi0 production or decay above LHC energies. The other two are less radical but nonetheless require significant modifications to existing hadron production models -- in one the changes are only above LHC energies and in the other the changes extend to much lower energies. We show that the models have distinctively different predictions for the correlation between the number of muons at ground and Xmax in hybrid...

Allen, Jeffrey

2013-01-01

325

What determines cloud radiative forcing in a cloud resolving model?  

Science.gov (United States)

We show that the cloud radiative forcing in a cloud resolving model run to radiative convective equilibrium is sensitive to the microphysics parameterizations used and not model conditions such as sea surface temperature, domain size, or even the use of a mixed layer ocean in place of fixed SSTs. Using the model's microphysics, we find that the shortwave cloud radiative forcing is larger in magnitude than the longwave cloud radiative forcing - in contrast to observations where they are nearly equal. When we tune the microphysics following the methods of Lopez et al. (2009), we produce a simulated MODIS histogram of optical depths and cloud top temperatures that more closely matches observations over the Tropical West Pacific (compared to the model's base microphysics) as well as a net cloud radiative forcing near zero. Changes to surface conditions do little to alter the net cloud radiative forcing for either of the microphysics choices.

Harrop, B. E.; Hartmann, D. L.

2013-12-01

326

A statistical model for characterizing common air pollutants in air-conditioned offices  

Science.gov (United States)

Maintaining acceptable indoor air quality (IAQ) for a healthy environment is of primary concern, policymakers have developed different strategies to address the performance of it based on proper assessment methodologies and monitoring plans. It could be cost prohibitive to sample all toxic pollutants in a building. In search of a more manageable number of parameters for cost-effective IAQ assessment, this study investigated the probable correlations among the 12 indoor environmental parameters listed in the IAQ certification scheme of the Hong Kong Environment Protection Department (HKEPD) in 422 Hong Kong offices. These 12 parameters consists of nine indoor air pollutants: carbon dioxide (CO 2), carbon monoxide (CO), respirable suspended particulates (RSP), nitrogen dioxide (NO 2), ozone (O 3), formaldehyde (HCHO), total volatile organic compounds (TVOC), radon (Rn), airborne bacteria count (ABC); and three thermal comfort parameters: temperature ( T), relative humidity (RH) and air velocity ( V). The relative importance of the correlations derived, from largest to smallest loadings, was ABC, Rn, CO, RH, RSP, CO 2, TVOC, O 3, T, V, NO 2 and HCHO. Together with the mathematical expressions derived, an alternative sampling protocol for IAQ assessment with the three 'most representative and independent' parameters namely RSP, CO 2 and TVOC measured in an office environment was proposed. The model validity was verified with on site measurements from 43 other offices in Hong Kong. The measured CO 2, RSP and TVOC concentrations were used to predict the probable levels of the other nine parameters and good agreement was found between the predictions and measurements. This simplified protocol provides an easy tool for performing IAQ monitoring in workplaces and will be useful for determining appropriate mitigation measures to finally honor the certification scheme in a cost-effective way.

Wong, L. T.; Mui, K. W.; Hui, P. S.

327

The IRBEM library -- open source tools for radiation belt modeling  

Science.gov (United States)

The COSPAR Panel on Radiation Belt Models sponsors an open-source library of software routines for radiation belt modeling, the International Radiation Belt Models (IRBEM) library (irbem.sf.net). Descended from the ONERA-DESP library, the IRBEM library contains primarily Fortran routines for magnetic field model evaluation and tracing, coordinate transforms, orbit propagation, radiation models, and neutral atmosphere models. The library can be accessed from several popular languages via a dynamic linked library (DLL) interface. Extra capabilities that have not been integrated into the library are provided for computing particle diffusion coefficients, training and evaluating neural networks, evaluating instrument response functions, inverting particle measurements from data channels to flux spectra, fast nearest-neighbors look-ups, and sharing structured data between high level languages. The IRBEM library continues to grow to meet the changing needs of radiation belt researchers.

O'Brien, P. P.; Bourdarie, S.

2012-12-01

328

Optimal Missile Avoidance and Improved Air Combat Models.  

Science.gov (United States)

The research efforts under this contract were oriented to solve two different air combat problems: optimal missile avoidance and medium range air-to-air interception. In both topics closed from solutions were obtained using either optimal control or diffe...

J. Shinar

1980-01-01

329

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

330

Spatial variation regularities of cosmic radiation and evaluation of exposure doses to air crews  

International Nuclear Information System (INIS)

This paper deals with the spatial variation regularities of cosmic radiation and the estimation of exposure doses to air crews. The instruments used for measurement were RSS-111 high pressure ionizing chamber, FD-3013 scintillation radiometer and BF3 proportional counter. Measurements were made in 15 types of aircraft on 55 flights, and also made in 5 types of aircraft at different altitudes over 10 airports. The measurements covered altitudes ranging from 0.5 to 15 km and geomagnetic latitudes ranging from 7 degree to 65 degree N. By measurements, the spatial variation regularities of cosmic radiation were deduced and the empirical formulas for ionizing component were obtained. The lowest value of annual effective dose received by a crew member who worked as many as 1000 hours a year would be 0.27 mSv, the median value 4.19 mSv and the highest value 10.56 mSv. Even the highest dose is considerably lower than the annual occupational limit of 20 mSv (averaged over five years) recently recommended by the International Commission on Radiological Protection. Some results of this study are compared with those in relevant published literature

1996-12-01

331

Downscaling modelling system for multi-scale air quality forecasting  

Science.gov (United States)

Urban modelling for real meteorological situations, in general, considers only a small part of the urban area in a micro-meteorological model, and urban heterogeneities outside a modelling domain affect micro-scale processes. Therefore, it is important to build a chain of models of different scales with nesting of higher resolution models into larger scale lower resolution models. Usually, the up-scaled city- or meso-scale models consider parameterisations of urban effects or statistical descriptions of the urban morphology, whereas the micro-scale (street canyon) models are obstacle-resolved and they consider a detailed geometry of the buildings and the urban canopy. The developed system consists of the meso-, urban- and street-scale models. First, it is the Numerical Weather Prediction (HIgh Resolution Limited Area Model) model combined with Atmospheric Chemistry Transport (the Comprehensive Air quality Model with extensions) model. Several levels of urban parameterisation are considered. They are chosen depending on selected scales and resolutions. For regional scale, the urban parameterisation is based on the roughness and flux corrections approach; for urban scale - building effects parameterisation. Modern methods of computational fluid dynamics allow solving environmental problems connected with atmospheric transport of pollutants within urban canopy in a presence of penetrable (vegetation) and impenetrable (buildings) obstacles. For local- and micro-scales nesting the Micro-scale Model for Urban Environment is applied. This is a comprehensive obstacle-resolved urban wind-flow and dispersion model based on the Reynolds averaged Navier-Stokes approach and several turbulent closures, i.e. k -É? linear eddy-viscosity model, k - É? non-linear eddy-viscosity model and Reynolds stress model. Boundary and initial conditions for the micro-scale model are used from the up-scaled models with corresponding interpolation conserving the mass. For the boundaries a kind of Dirichlet condition is chosen to provide the values based on interpolation from the coarse to the fine grid. When the roughness approach is changed to the obstacle-resolved one in the nested model, the interpolation procedure will increase the computational time (due to additional iterations) for meteorological/ chemical fields inside the urban sub-layer. In such situations, as a possible alternative, the perturbation approach can be applied. Here, the effects of main meteorological variables and chemical species are considered as a sum of two components: background (large-scale) values, described by the coarse-resolution model, and perturbations (micro-scale) features, obtained from the nested fine resolution model.

Nuterman, R.; Baklanov, A.; Mahura, A.; Amstrup, B.; Weismann, J.

2010-09-01

332

Evaluation of observation-fused regional air quality model results for population air pollution exposure estimation.  

Science.gov (United States)

In this study, Community Multiscale Air Quality (CMAQ) model was applied to predict ambient gaseous and particulate concentrations during 2001 to 2010 in 15 hospital referral regions (HRRs) using a 36-km horizontal resolution domain. An inverse distance weighting based method was applied to produce exposure estimates based on observation-fused regional pollutant concentration fields using the differences between observations and predictions at grid cells where air quality monitors were located. Although the raw CMAQ model is capable of producing satisfying results for O3 and PM2.5 based on EPA guidelines, using the observation data fusing technique to correct CMAQ predictions leads to significant improvement of model performance for all gaseous and particulate pollutants. Regional average concentrations were calculated using five different methods: 1) inverse distance weighting of observation data alone, 2) raw CMAQ results, 3) observation-fused CMAQ results, 4) population-averaged raw CMAQ results and 5) population-averaged fused CMAQ results. It shows that while O3 (as well as NOx) monitoring networks in the HRRs are dense enough to provide consistent regional average exposure estimation based on monitoring data alone, PM2.5 observation sites (as well as monitors for CO, SO2, PM10 and PM2.5 components) are usually sparse and the difference between the average concentrations estimated by the inverse distance interpolated observations, raw CMAQ and fused CMAQ results can be significantly different. Population-weighted average should be used to account for spatial variation in pollutant concentration and population density. Using raw CMAQ results or observations alone might lead to significant biases in health outcome analyses. PMID:24747248

Chen, Gang; Li, Jingyi; Ying, Qi; Sherman, Seth; Perkins, Neil; Rajeshwari, Sundaram; Mendola, Pauline

2014-07-01

333

Bibliography on Grey Literature on Air Quality Modeling, Part II. New Modeling Techniques.  

Science.gov (United States)

A worldwide cooperation in the field of modeling activities has proved the necessity to review the state of the art of air quality modeling and to show international trends in model standardization. An important point to fulfill the task was the registrat...

1978-01-01

334

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Ferreira, P. M.; Gomes, Joa?o M.; Martins, I.; Ruano, A. E.

2012-01-01

335

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

336

Air  

…or more complex industrial processes. Through our powers in pollution control, we also have an important role in working with Local Authorities, the Highways Agency and other organisations to deliver the Government??s Air Quality Strategy in England and Wales. Policy/position statements Click on the…

337

A mathematical model for radiation hydrodynamics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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,

Sebastiano Pennisi; Marco Sammartino

1990-01-01

338

Wave radiation in simple geophysical models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Wave radiation is an important process in many geophysical flows. In particular, it is by wave radiation that flows may adjust to a state for which the dynamics is slow. Such a state is described as “balanced”, meaning there is an approximate balance between the Coriolis force and horizontal pressure gradients, and between buoyancy and vertical pressure gradients. In this thesis, wave radiation processes relevant to these enormously complex flows are studied through the use...

Murray, Stuart William

2013-01-01

339

Air pollution in Danish cities. A model for measurement and control  

Energy Technology Data Exchange (ETDEWEB)

In order to control air quality, monitoring has been carried out in Danish cities since 1967. The purpose of this paper is to discuss the air pollution abatement legislation and, on the basis of air quality data from eight Danish cities, to model the development in 1982-1990 of air pollution from manufacturing and the house heating especially by suspended particulates, sulphur and sulphur dioxide. The model describes air pollution as a function of city size, weather and various abatement initiatives to improve the air quality. The basic approach used in the model building procedure is the expansion method. (au) (28 refs.)

Kristensen, G. [University of Odense. Dept. of Economics, Odense (Denmark); Palmgren Jensen, F. [National Environment Research Institute. Division for Emission and Air Pollution (Denmark)

1992-10-01

340

Shock Layer Radiation Modeling and Uncertainty for Mars Entry  

Science.gov (United States)

A model for simulating nonequilibrium radiation from Mars entry shock layers is presented. A new chemical kinetic rate model is developed that provides good agreement with recent EAST and X2 shock tube radiation measurements. This model includes a CO dissociation rate that is a factor of 13 larger than the rate used widely in previous models. Uncertainties in the proposed rates are assessed along with uncertainties in translational-vibrational relaxation modeling parameters. The stagnation point radiative flux uncertainty due to these flowfield modeling parameter uncertainties is computed to vary from 50 to 200% for a range of free-stream conditions, with densities ranging from 5e-5 to 5e-4 kg/m3 and velocities ranging from of 6.3 to 7.7 km/s. These conditions cover the range of anticipated peak radiative heating conditions for proposed hypersonic inflatable aerodynamic decelerators (HIADs). Modeling parameters for the radiative spectrum are compiled along with a non-Boltzmann rate model for the dominant radiating molecules, CO, CN, and C2. A method for treating non-local absorption in the non-Boltzmann model is developed, which is shown to result in up to a 50% increase in the radiative flux through absorption by the CO 4th Positive band. The sensitivity of the radiative flux to the radiation modeling parameters is presented and the uncertainty for each parameter is assessed. The stagnation point radiative flux uncertainty due to these radiation modeling parameter uncertainties is computed to vary from 18 to 167% for the considered range of free-stream conditions. The total radiative flux uncertainty is computed as the root sum square of the flowfield and radiation parametric uncertainties, which results in total uncertainties ranging from 50 to 260%. The main contributors to these significant uncertainties are the CO dissociation rate and the CO heavy-particle excitation rates. Applying the baseline flowfield and radiation models developed in this work, the radiative heating for the Mars Pathfinder probe is predicted to be nearly 20 W/cm2. In contrast to previous studies, this value is shown to be significant relative to the convective heating.

Johnston, Christopher O.; Brandis, Aaron M.; Sutton, Kenneth

2012-01-01

 
 
 
 
341

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

1977-11-21

342

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

343

Computer modelling of radiation-induced bystander effect  

Energy Technology Data Exchange (ETDEWEB)

Radiation-induced genomic instability and bystander effects are now well established consequences of exposure of living cells to ionising radiation. It has been observed that cells not directly hit by radiation tracks may still exhibit radiation effects. We present a quantitative modelling of the radiation-induced bystander effect based on a diffusion model of spreading the bystander signal. The model assumes the bystander factor to be a protein of low molecular weight, given out by the hit cell, diffusing in the medium and reacting with non-hit cells. The model calculations successfully predict the results of cell survival in an irradiated conditioned medium. The model predicts the shape of dose-effect relationship for cell survival and oncogenic transformation induced by broad-beam and micro-beam irradiation by alpha-particles. (author)

Khvostunov, Igor K. [Medical Radiological Research Centre, Obninsk (Russian Federation); Nikjoo, Hooshang [Medical Research Council, Radiation and Genome Stability Unit, Oxfordshire, Harwell (United Kingdom)]. E-mail: h.nikjoo@har.mrc.ac.uk

2002-09-01

344

Computer modelling of statistical properties of SASE FEL radiation  

International Nuclear Information System (INIS)

The paper describes an approach to computer modelling of statistical properties of the radiation from self amplified spontaneous emission free electron laser (SASE FEL). The present approach allows one to calculate the following statistical properties of the SASE FEL radiation: time and spectral field correlation functions, distribution of the fluctuations of the instantaneous radiation power, distribution of the energy in the electron bunch, distribution of the radiation energy after monochromator installed at the FEL amplifier exit and the radiation spectrum. All numerical results presented in the paper have been calculated for the 70 nm SASE FEL at the TESLA Test Facility being under construction at DESY

1997-06-01

345

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

1975-01-01

346

Combined natural convection and radiation heat transfer in a vertical air cavity with hexagonal honeycomb core of negligible thickness  

Energy Technology Data Exchange (ETDEWEB)

Combined natural convection and radiation heat transfer in a vertical air cavity with a hexagonal honeycomb core of negligible thickness are investigated numerically. The numerical methodology is based on an algebraic coordinate transformation and finite volume technique. Temperature of the honeycomb core wall is determined such that radiation, convection and conduction energy balances on the core wall are satisfied. The computations were performed for Ra = 10{sup 3} to 10{sup 5}, for an aspect ratio of H/L = 1, for Pr = 0.7, and for wide range of emissivities. Heat transfer rates by both convection and radiation are presented as a function of emissivity, and the effect of radiation on the natural convection is discussed. The results showed natural convection is affected by radiation although the layer is filled with a transparent gas. This effect is accentuated in the case of a very thin wall.

Asako, Y.; Yamaguchi, Y.; Chen, L. [Tokyo Metropolitan Univ. (Japan). Dept. of Mechanical Engineering; Faghri, M. [Univ. of Rhode Island, Kingston, RI (United States). Dept. of Mechanical Engineering and Applied Mechanics

1995-12-31

347

Radiative transfer modelling of dust devils  

Science.gov (United States)

Dust devils are particle laden convective vortices that form at the base of convective plumes. They are typically observed in dry desert climates on Earth and have been observed to form frequently on Mars. Meteorological measurements have also indicated that martian surface spacecraft have experienced numerous dust devil transits. To date, the characterisation of dust devils through the interpretation of spectral measurements of sunlight taken during a transit has yet to be investigated. Such measurements would provide valuable information of the physical size, dust load and internal structure of dust devils. A Monte Carlo Radiative Transfer (MCRT) model was developed to simulate the attenuation of sunlight through a dust devil and to investigate the observed spectral variation during such an event. The predicted transit signature resulting from a dust devil transit is highly dependent on the method of observation. The scattered light flux increases during the transit with the magnitude dependent on the dust concentration, making it sensitive to the internal dust distribution. This dependence is not observed for the total light flux which experiences a decrease and is strongly dependent on the total extinction through the vortex and insensitive to how the dust is distributed. The implication of this work is that separate in situ measurement of both the total and scattered flux is crucial for characterising dust devils and such measurements provide a powerful tool that could be exploited by future Mars missions.

Mason, Jonathon P.; Patel, Manish R.; Lewis, Stephen R.

2013-03-01

348

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 Rayleigh numbers are considerably increased by radiation. ? According to the thermal boundary conditions, combined analyses are required.

2011-05-01

349

CFD Modeling of Air Pocket Transport in Conjunction with Spillway Conduits  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

350

Validation study of air-sea gas transfer modeling  

Energy Technology Data Exchange (ETDEWEB)

Laboratory results have demonstrated the importance of bubble plumes to air-water gas transfer (Asher et al., 1994). Bubble plumes enhance gas transfer by disrupting surface films, by directly transporting a gas, and by the creation of turbulence. Models of bubble gas transfer have been developed by different authors (Atkinson, 1973; Memery and Merlivat, 1985; Woolf and Thorpe, 1991) to determine the magnitude of gas transfer due to bubbles. Laboratory measurements of both the gas transfer rate k{sub L}, and the bubble distribution {phi} in a whitecap simulation tank (WST) have allowed these models to be validated and deficiencies in the theoretical assumptions to be explored. In the WST, each bucket tip simulates a wave breaking event. Important tests of these models include whether they can explain the experimentally determined solubility and Schmidt number dependency of k{sub L}, predict the time varying bubble concentrations, predict the evasion-invasion asymmetry, and predict the fraction of k{sub L} due to bubble plumes. Four different models were tested, a steady state model (Atkinson, 1973), a non-turbulence model with constant bubble radius (Memery and Merlivat, 1985), a turbulence model with constant bubble radius (Wolf and Thorpe, 1991), and a turbulence model with varying bubble radius. All models simulated multiple bubble tip cycles. The two turbulence models were run for sufficient tip cycles to generate statistically significant number of eddies ({number_sign}{gt}50) for bubbles affected by turbulence (V{sub B}{le}V{sub T}), found to be at least four tip cycles. The models allowed up to nine gases simultaneously and were run under different conditions of trace and major gas concentrations and partial pressures.

Asher, W.E.; Farley, P.J. [Pacific Northwest Lab., Richland, WA (United States); Leifer, I.S. [Georgia Inst. of Tech., Atlanta, GA (United States)

1995-07-01

351

Environmental Radiation Effects on Mammals A Dynamical Modeling Approach  

CERN Multimedia

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

352

Water/air radiator for water-cooled internal combustion engines. Wasser/Luft Kuehler fuer wassergekuehlte Verbrennungskraftmaschinen  

Energy Technology Data Exchange (ETDEWEB)

This is a water/air radiator for water-cooled internal combustion engines, particularly of commercial vehicles, which consists of a radiator block held between water boxes and side parts. The side parts are connected at both ends by fixing straps overlapping over the water boxes at the sides to the water boxes. These fixing straps have openings through which connecting bolts connected to the water boxes pass. The straps can be held by spring clamps or by suitable stays on the connecting bolts themselves. This design of a water/air radiator can easily be mounted and is particularly suitable for a type where the water boxes are manufactured from plastic material.

Lenz, W.; Moest, M.

1986-02-13

353

The radiation performance standard. A presentation model for ionizing radiation in the living environment  

International Nuclear Information System (INIS)

By means of the so-called radiation performance standard (SPN, abbreviated in Dutch) the total radioactivity from building constructions which contributes to the indoor radiation dose can be calculated. The SPN is implemented with related boundary values and is part of the Building Decree ('Bouwbesluit') in the Netherlands. The model, presented in this book, forms the basis of a new Dutch radiation protection standard, to be published by the Dutch Institute for Standardization NEN (formerly NNI). 14 refs

1998-01-01

354

Modeled mesoscale meteorological fields with four-dimensional data assimilation in regional scale air quality models  

Energy Technology Data Exchange (ETDEWEB)

The paper addresses the need to increase the temporal and spatial resolution of meteorological data currently used in air quality simulation models, AQSMs. Transport and diffusion parameters including mixing heights and stability used in regulatory air quality dispersion models are currently computed using routinely collected twice daily (00Z and 12Z) upper air sounding data from approximately 100 locations, and hourly surface data from approximately 300 locations spread across the US. The limited resolution data base limits the accuracy, reliability and validity of the derived dispersion parameters for air quality models. The MM4-FDDA (Mesoscale Meteorological model, Version 4 with Four Dimensional Data Assimilation), a state-of-science dynamic modeling system that assimilates routinely available surface and upper air sounding data has been demonstrated to provide accurate and well characterized primary meteorological fields on hourly time intervals, with fine horizontal and vertical resolution. The MM4-FDDA can also provide as outputs, parameters such as surface heat and momentum fluxes which are necessary for computing the stability dispersion parameters. The goal of the study is to generate meteorological data with accuracy of transport, precipitation and dynamic consistency superior to both direct interpolation of synoptic scale analysis of observations and on-site meteorology, and purely predictive-mode model results. This is a demonstration project to produce a one year meteorological data base on an hourly basis for a horizontal grid resolution of 80 km and for 15 vertical layers is underway.

Ching, J.K.S.; Irwin, J.S.

1993-01-01

355

Cloud-precipitation-radiation-dynamics interaction in global climate models: A snow and radiation interaction sensitivity experiment  

Science.gov (United States)

global climate models (GCMs) often consider radiation interactions only with small-particle/suspended cloud mass, ignoring large-particle/falling and convective core cloud mass. We characterize the radiation and atmospheric circulation impacts of frozen precipitating hydrometeors (i.e., snow), using the National Center for Atmospheric Research coupled GCM, by conducting sensitivity experiments that turn off the radiation interaction with snow. The changes associated with the exclusion of precipitating hydrometeors exhibit a number differences consistent with biases in CMIP3 and CMIP5 (Coupled Model Intercomparison Project Phase 3 and Phase 5), including more outgoing longwave flux at the top of atmosphere and downward shortwave flux at the surface in the heavily precipitating regions. Neglecting the radiation interaction of snow increases the net radiative cooling near the cloud top with the resulting increased instability triggering more convection in the heavily precipitating regions of the tropics. In addition, the increased differential vertical heating leads to a weakening of the low-level mean flow and an apparent low-level eastward advection from the warm pool resulting in moisture convergence south of the Intertropical Convergence Zone and north of the South Pacific Convergence Zone (SPCZ). This westerly bias, with effective warm and moist air transport, might be a contributing factor in the model's northeastward overextension of the SPCZ and the concomitant changes in sea surface temperatures, upward motion, and precipitation. Broader dynamical impacts include a stronger local meridional overturning circulation over the middle and east Pacific and commensurate changes in low and upper level winds, large-scale ascending motion, with a notable similarity to the systematic bias in this region in CMIP5 upper level zonal winds.

Li, J.-L. F.; Lee, W.-L.; Waliser, D. E.; David Neelin, J.; Stachnik, Justin P.; Lee, Tong

2014-04-01

356

Consistent inclusion of radiation reaction into kinetic plasma modeling  

International Nuclear Information System (INIS)

Complete text of publication follows. Radiation properties of laser plasma and the resulting collective effects due to the radiation reaction force are relevant for the most powerful lasers interacting with matter available in the laboratory today. The contribution of the radiation reaction force to the total force acting on a charged particle moving in plasma is analyzed. Radiation is principally included in the standard calculation of self-consistent fields. Since the high frequency part of the emitted radiation cannot always be resolved in numerical simulations due to a finite time step one can think to include radiation reaction using a consistent physical model. For these purposes we have derived a modified kinetic equation which describes the radiation damping as a result of non-Hamiltonian dynamics in phase space due to the interaction with radiation. We use this equation for the derivation of moment equations for macro-particles. As physical models for the radiation force we use the classical Lorentz-Abraham-Dirac (LAD) and the Landau-Lifshitz equations derived from LAD. Both models are incorporated into a large scale Particle-In-Cell code to treat the radiation self-action in the classical validity range, i.e. when the recoil energy of scattered photons is not too big in comparison with the energy of the interacting electron. The model has clear advantages for the treatment of coherent effects in laser field-plasma interaction. We also discuss consistent matching with a more elaborated semi-classical radiation model. The model has no limit for the recoil energy but suffers from a lack of coherence. Both models have to be used together to simulate multi-scale processes of electron acceleration, highly brillant X-ray sources and QED effects, which may become important in the course of the ELI project. Acknowledgements. This work has been funded by the Munich Centre of Advanced Photonics.

2010-09-06

357

Radiation model predictions and validation using LDEF satellite data  

Science.gov (United States)

Predictions and comparisons with the radiation dose measurements on Long Duration Exposure Facility (LDEF) by thermoluminescent dosimeters were made to evaluate the accuracy of models currently used in defining the ionizing radiation environment for low Earth orbit missions. The calculations include a detailed simulation of the radiation exposure (altitude and solar cycle variations, directional dependence) and shielding effects (three-dimensional LDEF geometry model) so that differences in the predicted and observed doses can be attributed to environment model uncertainties. The LDEF dose data are utilized to assess the accuracy of models describing the trapped proton flux, the trapped proton directionality, and the trapped electron flux.

Armstrong, T. W.; Colborn, B. L.

1993-01-01

358

A physical model for electron radiation belts of Saturn  

Science.gov (United States)

Radiation belts cause irreversible damages to on-board instrument materials. Studies about radiation belts can provide precious information for future interplanetary missions. Pioneer 11, Voyager 2 and nowadays Cassini missions give the characteristics of Saturn's inner magnetosphere: Saturn's famous rings, various moons, neutral particles ejected from Enceladus and waves. Thanks to its experience with the Earth's and Jupiter's radiation belt studies, ONERA is now able to develop an electron radiation belt model for Saturn's environment, i.e., a new version of Salammbô. The study of Saturn's inner magnetosphere emphasizes the most important physical processes governing radiation belt dynamics: electrons losses due to dense rings are the dominant physical process near the planet (L ˜50 keV), radial diffusion and local losses due to the moons are predominant from L = 2.3 to the boundary condition (L = 6). The analysis of spacecraft in situ data (Pioneer 11, Voyager 2, and Cassini) allows a boundary condition to be built for the model and the Salammbô results to be validated. The Salammbô Kronian model has also been compared to the empirical radiation belt model SATRAD (for SATurn RADiation model) based on Pioneer 11 and Voyager 2 data. Comparisons of Salammbô results with in situ data and SATRAD confirm that Salammbô is a good mean model for Saturn electron radiation belts, for energies from about a hundred keV to a few MeV.

Lorenzato, Lise; Sicard, AngéLica; Bourdarie, SéBastien

2012-08-01

359

Numerical modelling of air movement in road tunnels  

International Nuclear Information System (INIS)

The objective of the Mechanical Ventilation Systems (MVS) in highway tunnels is to provide tunnel patrons with a reasonable degree of comfort during normal operation and to assist in keeping tunnels safe during emergencies. Temperature, humidity, and air velocity are among the parameters that determine the tunnel environment and indicate the level of MVS performance. To investigate the performance of the current emergency ventilation strategies for an existing tunnel system in the event of a fire, a research project is being conducted at the National Research Council of Canada. The primary objectives of the study are: a) to assess and validate the ability of in-place emergency ventilation strategies to control smoke spread and minimize the impact of smoke on tunnel users; and b) to recommend guidelines for improving ventilation operation to maximize intervention effectiveness. This will allow future development of an intelligent ventilation system based on a pre-established scenario of ventilation activated using automatic fire detection. The research study includes two phases, numerical and experimental phases. The numerical phase will use a CFD model (Solvent) to study smoke ventilation in the tunnel. The experimental phase will be used to calibrate and validate the CFD model and to establish the boundary conditions for the numerical model. Solvent was used to model a ventilation scenario using existing data. The current paper presents the initial efforts to validate the CFD model against onsite flow measurements conducted in the tunnel. The CFD model included aerodynamically significant physical features of the tunnel. (author)

2003-05-28

360

Improvement of local air coolers model in ISAAC  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to assess a new local air coolers (LACs) model in ISAAC 2.0, as ISAAC 1.0 could model LAC only at two locations. In the new model, LACs up to twelve locations could be handled. Large LOCA and Loss of Feed Water sequences were selected for the model comparison. Two cases were analyzed with ISAAC 2.0: one with 6 LACs in one of the fueling machine room and in the steam generator room, respectively, and the other with 3 LACs at both fueling machine room and 6 LACs in the steam generator room. The study assumes that the safety systems such as Emergency Core Cooling System, Shield Cooling System and Moderator Cooling System are unavailable. According to the results, the new LACs model showed almost no difference between two cases. Also it was found that as the location of LACs increased, the new model worked properly and the effect of LACs was consistent regardless the accident initiators.

Kim, S. D.; Kim, D. H.; Park, S. Y. [KAERI, Taejon (Korea, Republic of)

2004-07-01

 
 
 
 
361

Improvement of local air coolers model in ISAAC  

International Nuclear Information System (INIS)

The purpose of this paper is to assess a new local air coolers (LACs) model in ISAAC 2.0, as ISAAC 1.0 could model LAC only at two locations. In the new model, LACs up to twelve locations could be handled. Large LOCA and Loss of Feed Water sequences were selected for the model comparison. Two cases were analyzed with ISAAC 2.0: one with 6 LACs in one of the fueling machine room and in the steam generator room, respectively, and the other with 3 LACs at both fueling machine room and 6 LACs in the steam generator room. The study assumes that the safety systems such as Emergency Core Cooling System, Shield Cooling System and Moderator Cooling System are unavailable. According to the results, the new LACs model showed almost no difference between two cases. Also it was found that as the location of LACs increased, the new model worked properly and the effect of LACs was consistent regardless the accident initiators

2004-05-27

362

Canopy radiation transmission for an energy balance snowmelt model  

Science.gov (United States)

To better estimate the radiation energy within and beneath the forest canopy for energy balance snowmelt models, a two stream radiation transfer model that explicitly accounts for canopy scattering, absorption and reflection was developed. Upward and downward radiation streams represented by two differential equations using a single path assumption were solved analytically to approximate the radiation transmitted through or reflected by the canopy with multiple scattering. This approximation results in an exponential decrease of radiation intensity with canopy depth, similar to Beer's law for a deep canopy. The solution for a finite canopy is obtained by applying recursive superposition of this two stream single path deep canopy solution. This solution enhances capability for modeling energy balance processes of the snowpack in forested environments, which is important when quantifying the sensitivity of hydrologic response to input changes using physically based modeling. The radiation model was included in a distributed energy balance snowmelt model and results compared with observations made in three different vegetation classes (open, coniferous forest, deciduous forest) at a forest study area in the Rocky Mountains in Utah, USA. The model was able to capture the sensitivity of beneath canopy net radiation and snowmelt to vegetation class consistent with observations and achieve satisfactory predictions of snowmelt from forested areas from parsimonious practically available information. The model is simple enough to be applied in a spatially distributed way, but still relatively rigorously and explicitly represent variability in canopy properties in the simulation of snowmelt over a watershed.

Mahat, Vinod; Tarboton, David G.

2012-01-01

363

The ``KILDER`` air pollution modelling system, version 2.0  

Energy Technology Data Exchange (ETDEWEB)

This report describes the KILDER Air Pollution Modelling System, which is a system of small PC-programs for calculation of long-term emission, dispersion, concentration and exposure from different source categories. The system consists of three parts: (1) The dispersion models POI-KILD and ARE-KILD for point- and area-sources, respectively, (2) Meterological programs WINDFREC, STABFREC and METFREC, (3) Supporting programs for calculating emissions and exposure and for operating with binary data fields. The file structure is based on binary files with data fields. The data fields are matrices with different types of values and may be read into the computer or be calculated in other programs. 19 refs., 22 figs., 3 tabs.

Gram, F.

1996-12-31

364

Future Air Traffic Growth and Schedule Model User's Guide  

Science.gov (United States)

The Future Air Traffic Growth and Schedule Model was developed as an implementation of the Fratar algorithm to project future traffic flow between airports in a system and of then scheduling the additional flights to reflect current passenger time-of-travel preferences. The methodology produces an unconstrained future schedule from a current (or baseline) schedule and the airport operations growth rates. As an example of the use of the model, future schedules are projected for 2010 and 2022 for all flights arriving at, departing from, or flying between all continental United States airports that had commercial scheduled service for May 17, 2002. Inter-continental US traffic and airports are included and the traffic is also grown with the Fratar methodology to account for their arrivals and departures to the continental US airports. Input data sets derived from the Official Airline Guide (OAG) data and FAA Terminal Area Forecast (TAF) are included in the examples of the computer code execution.

Kimmel, William M. (Technical Monitor); Smith, Jeremy C.; Dollyhigh, Samuel M.

2004-01-01

365

Future Air Traffic Growth and Schedule Model, Supplement  

Science.gov (United States)

The Future Air Traffic Growth and Schedule Model was developed as an implementation of the Fratar algorithm to project future traffic flow between airports in a system and of then scheduling the additional flights to reflect current passenger time-of-travel preferences. The methodology produces an unconstrained future schedule from a current (or baseline) schedule and the airport operations growth rates. As an example of the use of the model, future schedules are projected for 2010 and 2022 for all flights arriving at, departing from, or flying between all continental United States airports that had commercial scheduled service for May 17, 2002. Inter-continental US traffic and airports are included and the traffic is also grown with the Fratar methodology to account for their arrivals and departures to the continental US airports. Input data sets derived from the Official Airline Guide (OAG) data and FAA Terminal Area Forecast (TAF) are included in the examples of the computer code execution.

Kimmel, William M. (Technical Monitor); Smith, Jeremy C.; Dollyhigh, Samuel M.

2004-01-01

366

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

Science.gov (United States)

...and Transport. Academic Press, New York...Critical Review. Journal of the Air Pollution...boundary layer. Journal of Applied Meteorology...Meteorology. Kluwer Academic Publishers, Boston... , 1976. The Chemistry, Dispersion...EPA-HIWAY Model. Journal of the Air...

2010-07-01

367

Radiation exposure modeling and project schedule visualization  

International Nuclear Information System (INIS)

This paper discusses two applications using IGRIP (Interactive Graphical Robot Instruction Program) to assist environmental remediation efforts at the Department of Energy (DOE) Hanford Site. In the first application, IGRIP is used to calculate the estimated radiation exposure to workers conducting tasks in radiation environments. In the second, IGRIP is used as a configuration management tool to detect interferences between equipment and personnel work areas for multiple projects occurring simultaneously in one area. Both of these applications have the capability to reduce environmental remediation costs by reducing personnel radiation exposure and by providing a method to effectively manage multiple projects in a single facility

1995-10-09

368

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 dosimetry measurements for external beam dose verification, while offering significant advantages in convenience and efficiency for routine use.

2011-08-14

369

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

2007-11-19

370

Modeling radiation chemistry and biology in the Geant4 toolkit  

International Nuclear Information System (INIS)

Simulation of biological effects of ionizing radiation at the DNA scale requires not only the modeling of direct damages induced on DNA by the incident radiation and by secondary particles but also the modeling of indirect effects of radiolytic products resulting from water radiolysis. They can provoke single and double strand breaks by reacting with DNA. The Geant4 Monte Carlo toolkit is currently being extended for the simulation of biological damages of ionizing radiation at the DNA scale in the framework of the 'Geant4-DNA' project. Physics models for the modeling of direct effects are already available in Geant4. In the present paper, an approach for the modeling of radiation chemistry in pure liquid water within Geant4 is presented. In particular, this modeling includes Brownian motion and chemical reactions between molecules following water radiolysis. First results on time-dependent radiochemical yields from 1 picosecond up to 1 microsecond after irradiation are compared to published data and discussed. (author)

2010-10-17

371

Radiative Forcing by Long-Lived Greenhouse Gases: Calculations with the AER Radiative Transfer Models  

Energy Technology Data Exchange (ETDEWEB)

A primary component of the observed, recent climate change is the radiative forcing from increased concentrations of long-lived greenhouse gases (LLGHGs). Effective simulation of anthropogenic climate change by general circulation models (GCMs) is strongly dependent on the accurate representation of radiative processes associated with water vapor, ozone and LLGHGs. In the context of the increasing application of the Atmospheric and Environmental Research, Inc. (AER) radiation models within the GCM community, their capability to calculate longwave and shortwave radiative forcing for clear sky scenarios previously examined by the radiative transfer model intercomparison project (RTMIP) is presented. Forcing calculations with the AER line-by-line (LBL) models are very consistent with the RTMIP line-by-line results in the longwave and shortwave. The AER broadband models, in all but one case, calculate longwave forcings within a range of -0.20 to 0.23 W m{sup -2} of LBL calculations and shortwave forcings within a range of -0.16 to 0.38 W m{sup -2} of LBL results. These models also perform well at the surface, which RTMIP identified as a level at which GCM radiation models have particular difficulty reproducing LBL fluxes. Heating profile perturbations calculated by the broadband models generally reproduce high-resolution calculations within a few hundredths K d{sup -1} in the troposphere and within 0.15 K d{sup -1} in the peak stratospheric heating near 1 hPa. In most cases, the AER broadband models provide radiative forcing results that are in closer agreement with high 20 resolution calculations than the GCM radiation codes examined by RTMIP, which supports the application of the AER models to climate change research.

Collins, William; Iacono, Michael J.; Delamere, Jennifer S.; Mlawer, Eli J.; Shephard, Mark W.; Clough, Shepard A.; Collins, William D.

2008-04-01

372

Modelling and visualisation to support decision-making in air quality-related transport planning  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis introduces three main elements to support decision-making in air quality-related transport planning. The first are novel automatic collection and processing algorithms for traffic flow and geospatial data for input to air pollution models of transport schemes under analysis. The second is a novel strategy to improve the modelling of air quality by the calibration of input background concentrations. The third is a novel 3D air pollution dispersion interface for the 3D visualisation...

2010-01-01

373

FLUKA realistic modeling of radiation induced damage  

International Nuclear Information System (INIS)

The prediction of the structural damage to materials under irradiation is essential to evaluate consequences due to long term employment of construction materials in nuclear reactors and charged particle accelerators. The present paper describes the implementation to radiation damage effects in the particle transport code FLUKA for all particles and compares the results with the numerical evaluations available in the literature. In contrast with the implementation in other codes, we decided not to employ the Lindhard partition function but rather rework the formulas for an equivalent partition function restricted in energy above a user defined damage threshold. The implementation is based on the integration of the 'universal' potential using realistic form factors, allowing for calculation of the restricted nuclear energy losses dEnucEth / dx = N?EthEmax T d?/dT dT for the recoils above a certain fraction of energy. The integration was performed in the 'reduced energy' frame to remote any dependence of the projectile and target nucleus. The results obtained were used in a two-dimensional fit with a tolerance less than 5% spanning over nine orders of magnitude. Based on the fitting, during run-time FLUKA is able to predict in an accurate way the number of recoils (and subsequent sub-cascade of the recoils) which has the power to induce damage to the material. Finally the conversion to dpa is performed by using a modified Kinchin-Pease damage model and taking into account the effect on the displacement efficiency for higher recoil energies due to recombination and migration of the Frenkel pairs. All charged particles including leptons, hadrons and heavy ions, benefit from the algorithm. However for neutron interactions, photo-nuclear interactions, Bremsstrahlung, pair production, Compton scattering the recoil nucleus is either calculated analytically or sampled from a distribution and is further subject to the above algorithm for the damage estimation. (author)

2010-10-17

374

Dark radiation from a unified dark fluid model  

CERN Document Server

We present a unified dark fluid model to describe the possible evolutionary behavior of $\\Delta N_\\mathrm{eff}$ in dark radiation. This model can be viewed as an interacting model for the dark sectors, in which dark matter interacts with dark radiation. We show that the evolution of $\\Delta N_\\mathrm{eff}$ can be nicely explained without some drawbacks, such as the blowup of $\\Delta N_\\mathrm{eff}$ at the late time and the interaction term at the early time.

Geng, Chao-Qiang; Zhang, Xin

2013-01-01

375

Verification of SpacePy's radial diffusion radiation belt model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Model verification, or the process of ensuring that the prescribed equations are properly solved, is a necessary step in code development. Careful, quantitative verification guides users when selecting grid resolution and time step and gives confidence to code developers that existing code is properly instituted. This work introduces the RadBelt radiation belt model, a new, open-source version of the Dynamic Radiation Environment Assimilation Model (DREAM) and uses the Method of Manufactured ...

Welling, D. T.; Koller, J.; Camporeale, E.

2011-01-01

376

Verification of SpacePy's radial diffusion radiation belt model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Model verification, or the process of ensuring that the prescribed equations are properly solved, is a necessary step in code development. Careful, quantitative verification guides users when selecting grid resolution and time step and gives confidence to code developers that existing code is properly instituted. This work introduces the RadBelt radiation belt model, a new, open-source version of the Dynamic Radiation Environment Assimilation Model (DREAM) and uses the Method of Manufactured ...

Welling, D. T.; Koller, J.; Camporeale, E.

2012-01-01

377

Modelling relationships between lichen bioindicators, air quality and climate on a national scale: Results from the UK OPAL air survey  

International Nuclear Information System (INIS)

Air pollution has many negative effects on the natural environment, from changes in plant growth patterns to loss of ecosystem function. This study uses citizen science to investigate national-scale patterns in the distribution and abundance of selected lichen species on tree trunks and branches, and to relate these to air pollution and climate. Volunteers collected data for nine lichen indicators on 19,334 deciduous trees. Submitted data provided information on species-level patterns, and were used to derive composite lichen indices. Multiple linear regression and ANCOVA were used to model the relationships between lichen response variables on Quercus spp. and pollution, climate and location. The study demonstrated significant relationships between patterns in indicator lichens and levels of N- and S-containing pollutants on trunks and twigs. The derived lichen indices show great potential as a tool to provide information on local, site-specific levels of air quality. -- Highlights: •Data on presence and abundance of selected lichens were collected by members of the public. •Indicator species and indices were modelled against air pollution and climate data. •Lichens and indices show significant relationships with nitrogenous air pollution. •Lichen indices are useful tools for providing information on local air quality. -- Data on selected lichen taxa collected by members of the public in England is used to show the relationship of indicator taxa and pollution indices to air pollution and climate data

2013-11-01

378

The NIAID Radiation Countermeasures Program Business Model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The National Institute of Allergy and Infectious Diseases (NIAID) Radiation/Nuclear Medical Countermeasures Development Program has developed an integrated approach to providing the resources and expertise required for the research, discovery, and development of radiation/nuclear medical countermeasures (MCMs). These resources and services lower the opportunity costs and reduce the barriers to entry for companies interested in working in this area and accelerate translational progress by prov...

2010-01-01

379

A BAYESIAN MODEL COMMITTEE APPROACH TO FORECASTING GLOBAL SOLAR RADIATION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper proposes to use a rather new modelling approach in the realm of solar radiation forecasting. In this work, two forecasting models: Autoregressive Moving Average (ARMA) and Neural Network (NN) models are combined to form a model committee. The Bayesian inference is used to affect a probability to each model in the committee. Hence, each model's predictions are weighted by their respective probability. The models are fitted to one year of hourly Global Horizontal Irradiance (GHI) mea...

Lauret, Philippe; Rodler, Auline; Muselli, Marc; David, Mathieu; Diagne, Hadja Mai?mouna; Voyant, Cyril

2012-01-01

380

Radiative accelerations for evolutionary model calculations  

International Nuclear Information System (INIS)

Monochromatic opacities from the OPAL database have been used to calculate radiative accelerations for the 21 included chemical species. The 104 frequencies used are sufficient to calculate the radiative accelerations of many elements for T>105K, using frequency sampling. This temperature limit is higher for less abundant elements. As the abundances of Fe, He, or O are varied, the radiative acceleration of other elements changes, since abundant elements modify the frequency dependence of the radiative flux and the Rosseland opacity. Accurate radiative accelerations for a given element can only be obtained by allowing the abundances of the species that contribute most to the Rosseland opacity to vary during the evolution and recalculating the radiative accelerations and the Rosseland opacity during the evolution. There are physical phenomena that cannot be included in the calculations if one uses only the OPAL data. For instance, one should correct for the momentum given to the electron in a photoionization. Such effects are evaluated using atomic data from Opacity Project, and correction factors are given. copyright 1998 The American Astronomical Society

1998-01-01