WorldWideScience
 
 
1

Model for combined radiation-temperature accelerated aging of PVC and polyethylene in air  

International Nuclear Information System (INIS)

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

1984-01-01

2

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

International Nuclear Information System (INIS)

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

1984-01-01

3

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

International Nuclear Information System (INIS)

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

1999-01-01

4

Probabilistic model evaluation of continuous air monitor response for meeting radiation protection goals.  

UK PubMed Central (United Kingdom)

Effective continuous air monitor (CAM) programs can eliminate or significantly reduce the amount of inhaled radioactive material following an accidental release. Numerous factors impact the levels of protection CAM programs provide to the workers during these releases. These factors range from those related to the capability of the CAM instrument (e.g., CAM alarm set point and length of counting intervals) to those related to CAM placement in the room relative to dispersion rates and patterns of the released material in a room. While the impact of many of these factors on alarm sensitivity has been investigated in isolation, there are no methods for holistic evaluations of CAM programs relative to radiation protection goals (RPGs) or the contribution of the factors, either individually or combined, toward limiting worker dose. In this study, worker exposure was predicted using CAM response models developed to evaluate protection levels for continuous and acute releases. Monte Carlo simulations of 10,000 releases were performed using various combinations of model parameter values, with associated uncertainty distributions, to assess the expected ability of a CAM program to meet RPGs, and, further, to assess the relative influence of each factor toward lowering worker exposure. Results showed that improvements to CAM instrument capability combined with better ventilation and CAM placement improve worker protection nonlinearly and that these improvements are critical to meet RPGs. The sensitivity analysis showed that ventilation-driven dilution had the greatest impact on exposure reduction with the selected counting interval for alarm decisions and the alarm set point as secondarily important.

Whicker JJ; Justus AL

2009-09-01

5

Equivalent-radius scatter-air ratio model for inhomogeneity and irregular field corrections in radiation teletherapy  

Energy Technology Data Exchange (ETDEWEB)

In the field of medical radiation therapy, a goal of the health professionals is to be able to treat the patient with that amount of radiation dose prescribed by the oncologist. The calculation of the treatment time required on a given therapy machine is not a simple, straightforward task, and involves the consideration of location of the treatment area, patient contour, tissue heterogeneities, blocked fields, etc. Because of the many variables affecting the delivery of a radiation dose, the acceptable error in the calculation of the actual dose is 2-3%. To accurately account for these variables, the Equivalent-Radius Scatter-Air-Ratio (ESRSAR) Model has been developed which uses three-dimensional electron density data to correct for inhomogeneities of the medium that the photon radiation beam traverses. This model corrects for inaccuracies in the Equivalent Tissue-Air-Ratio (ETAR) method, and is significantly faster than the method of Wong and Henkelman. The corrected tissue-air ratio (TAR) values are found by separately calculating the primary dose (TAR of zero-field size), first scatter-dose (1st SAR), and multiple-scatter dose (multiple SAR). The primary is found by the water-equivalent-depth method. First scatter is calculated directly using ray-tracing. The multiple-scatter calculation uses coalescing, analogous to the ETAR method. In addition to accounting for inhomogeneities, this method will also simultaneously correct for irregular (blocked) fields.

Erb, J.C.

1985-01-01

6

Mixed radiation in air  

International Nuclear Information System (INIS)

[en] Five laboratories were selected to effect the irradiation of dosemeters under the European programme of intercomparison. Responsibility for 'mixed' radiation irradiation, the specification of which was defined at the meeting held in Luxembourg on 18-19 June 1981, was entrusted to the Service Technique d'Equipements de Protection et de Dosimetrie, Laboratoire d'Instrumentation et de Dosimetrie of the French Commissariat a l'Energie Atomique, at the Centre d'Etudes Nucleaires at Fontenay-aux-Roses (CEA-STEPD-LID, CENFAR). The irradiation equipment used forms part of the ionizing radiation calibration set at the French National Metrology Office, and the instruments are themselves calibrated against the national calibration standards maintained by the primary laboratory, the Laboratoire de Mesure des Rayonnements Ionisants (LMRI - CEA - SACLAY). Although the references for calibration of exposure to photon radiation beams used were themselves calibrated against the national calibration standards in the 'ionizing radiation' set, a direct intercomparison of these references has been made with the aid of an instrument in the possession of the RIV laboratory at Bilthoven. The results are described in another paper presented at this seminar, and those participating in the intercomparison should refer to it before drawing any definite conclusions about their own dosemeters. Range of X-ray energies and the required energy correction factor was obtained by interpolation. The standard temperature and pressure correction factors were, of course, applied. It is estimated that the overall accuracy on the exposure measurements at the 95% confidence limits is ± 2%. 62 dosemeters were exposed from 28 participants. Some establishments sent both TLD and film dosemeters while the majority sent either one type or the other

1981-06-00

7

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.

2009-01-01

8

Development of advanced cloud parameterizations to examine air quality, cloud properties, and cloud-radiation feedback in mesoscale models  

Energy Technology Data Exchange (ETDEWEB)

The distribution of atmospheric pollutants is governed by dynamic processes that create the general conditions for transport and mixing, by microphysical processes that control the evolution of aerosol and cloud particles, and by chemical processes that transform chemical species and form aerosols. Pollutants emitted into the air can undergo homogeneous gas reactions to create a suitable environment for the production by heterogeneous nucleation of embryos composed of a few molecules. The physicochemical properties of preexisting aerosols interact with newly produced embryos to evolve by heteromolecular diffusion and coagulation. Hygroscopic particles wig serve as effective cloud condensation nuclei (CCN), while hydrophobic particles will serve as effective ice-forming nuclei. Clouds form initially by condensation of water vapor on CCN and evolve in a vapor-liquid-solid system by deposition, sublimation, freezing, melting, coagulation, and breakup. Gases and aerosols that enter the clouds undergo aqueous chemical processes and may acidity hydrometer particles. Calculations for solar and longwave radiation fluxes depend on how the respective spectra are modified by absorbers such as H{sub 2}O, CO{sub 2}, O{sub 3}, CH{sub 4}, N{sub 2}O, chlorofruorocarbons, and aerosols. However, the flux calculations are more complicated for cloudy skies, because the cloud optical properties are not well defined. In this paper, key processes such as tropospheric chemistry, cloud microphysics parameterizations, and radiation schemes are reviewed in terms of physicochemical processes occurring, and recommendations are made for the development of advanced modules applicable to mesoscale models.

Lee, In Young

1993-09-01

9

Interregional air pollution modelling  

Energy Technology Data Exchange (ETDEWEB)

This book presents information on the following topics: general features of interregional transport models; air pollution components; numerical methods; deposition; removal and transformation processes in the atmosphere with respect to SO/sub 2/ and NO /SUB x/ ; chemical conversion in the atmosphere; concentration of hydroxyl radicals in ambient air; conversion of sulfur dioxide; nitrogen oxides; a comparison between four different interregional air pollution models; dispersion from a hypothetical source in a homogeneous flow field; data bases; and analysis of phases.

Zwerver, S.; Van Ham, J.

1985-01-01

10

Radiation control coatings installed on federal buildings at Tyndall Air Force Base. Volume 2: Long-term monitoring and modeling  

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy`s (DOE`s) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the federal sector. One such effort, the New Technology Demonstration Program (NTDP), seeks to evaluate new energy-saving US technologies and secure their more timely adoption by the US government. Through a partnership with a federal site, the utility serving the site, a manufacturer of an energy-related technology, and other organizations associated with these interests, DOE can evaluate a new technology. The results of the program give federal agency decision makers more hands-on information with which to validate a decision to utilize a new technology in their facilities. This is the second volume of a two-volume report that describes the effects of radiation control coatings installed on federal buildings at Tyndall Air Force Base (AFB) in Florida by ThermShield International. ORNL`s Buildings Technology Center (BTC) was assigned the responsibility for gathering, analyzing, and reporting on the data to describe the effects of the coatings. The first volume described the monitoring plan and its implementation, the results of pre-coating monitoring, the coating installation, results from fresh coatings compared to pre-coating results, and a plan to decommission the monitoring equipment. This second volume updates and completes the presentation of data to compare performance of fresh coatings with weathered coatings.

Petrie, T.W.; Childs, P.W.

1998-06-01

11

A general model for estimation of daily global solar radiation using air temperatures and site geographic parameters in Southwest China  

Science.gov (United States)

Estimation of daily global solar radiation (Rs) from routinely measured temperature data has been widely developed and used in many different areas of the world. However, many of them are site specific. It is assumed that a general model for estimating daily Rs using temperature variables and geographical parameters could be achieved within a climatic region. This paper made an attempt to develop a general model to estimate daily Rs using routinely measured temperature data (maximum (Tmax, °C) and minimum (Tmin, °C) temperatures) and site geographical parameters (latitude (La, °N), longitude (Ld, °E) and altitude (Alt, m)) for Guizhou and Sichuan basin of southwest China, which was classified into the hot summer and cold winter climate zone. Comparison analysis was carried out through statistics indicators such as root mean squared error of percentage (RMSE%), modeling efficiency (ME), coefficient of residual mass (CRM) and mean bias error (MBE). Site-dependent daily Rs estimating models were calibrated and validated using long-term observed weather data. A general formula was then obtained from site geographical parameters and the better fit site-dependent models with mean RMSE% of 38.68%, mean MBE of 0.381 MJ m?2 d?1, mean CRM of 0.04 and mean ME value of 0.713.

Li, Mao-Fen; Fan, Li; Liu, Hong-Bin; Guo, Peng-Tao; Wu, Wei

2013-01-01

12

Air quality model guideline  

International Nuclear Information System (INIS)

Alberta Environment has developed a guidelines for operations and proposed operations that require approvals under the province's Environmental Protection and Enhancement Act or that operate under a code of practice for emissions to the atmosphere. In an effort to ensure consistency in the use of dispersion models for regulatory applications in Alberta, this document provided detailed guidance on suitable methods and approaches that should be employed to assess air quality from emission sources, specifically, information required to demonstrate that a source meets the Alberta ambient air quality objectives. The document outlined the statutory authority and provided an overview of the approach. It provided detailed advice on the types and uses of dispersion models with particular reference to the modelling protocol, input data, and output interpretation. Guidance on the application of regulatory models were also presented. Various models were described and their intended uses were explained. Internet addresses for different modelling resources were also offered. Last, some information about regional modelling in the province of Alberta was discussed. 40 refs., 4 tabs., 7 figs., 3 appendices.

2009-01-01

13

Ozone and NO2 air-mass factors for zenith-sky spectrometers: Intercomparison of calclations with different radiative transfer models  

Energy Technology Data Exchange (ETDEWEB)

An intercomparison between results from the different radiative transfer models used to calculate air-mass factors (AMFs) at twilight is presented. The comparison was made for ozone AMFs at 510 nm and for NO2 AMFs at 440 nm. Vertical profiles were specified. Results are presented firstly for calculations in a pure Rayleigh atmosphere, then including background aerosols. Relative differences between calculated AMFs from different models cause relative errors in vertical columns of ozone and NO2 measured by zenith-sky spectrometers. For commonly used averages over solar zenith angles, these relative errors are +/- 2.3% in the vertical column of ozone and +/- 1.1% in the vertical column of NO2. Refinements to the calculations, suggested by intercomparison, should reduce these errors to +/- 1.0% for ozone and +/- 0.5% for NO2.

Sarkissian, A.; Roscoe, H.K.; Fish, D.; Van Roozendael, M.; Gil, M.; Chen, H.B.; Wang, P.; Pommereau, J.P.; Lenoble, J. [BAS, Cambridge (United Kingdom)]|[UCAM, Cambridge (United Kingdom)]|[IASB, Brussels (Belgium)]|[INTA, Madrid (Spain)]|[LOA, Villeneuve d`Ascq (France)]|[SA (France)

1995-05-01

14

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

15

Mental models of radiation  

International Nuclear Information System (INIS)

[en] Laymen and experts participated in interviews designed to reveal their 'mental models' of the processes potentially causing the miscommunications between experts and the public. We analyzed their responses in terms of an 'expert model' circumscribing scientifically relevant information. From results, there are gaps even between experts. Experts on internal exposure focused mainly on artificial radiation and high level of radiation. Experts on radiation biology focused on medical radiation, level of risk, environmental radiation, and hot springs. Experts on dosimetric performance focused on atomic power generation and needs of radiological protection. It means that even experts, they have interests only on their own specialized field. (author)

2005-01-01

16

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)

2009-01-01

17

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

2010-01-01

18

Response of air stagnation frequency to anthropogenically enhanced radiative forcing.  

UK PubMed Central (United Kingdom)

Stagnant atmospheric conditions can lead to hazardous air quality by allowing ozone and particulate matter to accumulate and persist in the near-surface environment. By changing atmospheric circulation and precipitation patterns, global warming could alter the meteorological factors that regulate air stagnation frequency. We analyze the response of the National Climatic Data Center (NCDC) Air Stagnation Index (ASI) to anthropogenically enhanced radiative forcing using global climate model projections of late-21(st) century climate change (SRES A1B scenario). Our results indicate that the atmospheric conditions over the highly populated, highly industrialized regions of the eastern United States, Mediterranean Europe, and eastern China are particularly sensitive to global warming, with the occurrence of stagnant conditions projected to increase 12-to-25% relative to late-20(th) century stagnation frequencies (3-18+ days/year). Changes in the position/strength of the polar jet, in the occurrence of light surface winds, and in the number of precipitation-free days all contribute to more frequent late-21(st) century air mass stagnation over these high-population regions. In addition, we find substantial inter-model spread in the simulated response of stagnation conditions over some regions using either native or bias corrected global climate model simulations, suggesting that changes in the atmospheric circulation and/or the distribution of precipitation represent important sources of uncertainty in the response of air quality to global warming.

Horton DE; Harshvardhan; Diffenbaugh NS

2012-01-01

19

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

20

Estimation of monthly solar radiation from measured air temperature extremes  

UK PubMed Central (United Kingdom)

Solar radiation (R s), a very important variable in agricultural meteorology, is measured at a very limited number of meteorological stations worldwide. However, a number of methods are reported in the literature for estimating R s from routinely measured air temperature extremes, the accuracy of which needs to be tested. R s was thus estimated by different methods for 29 stations distributed throughout India. The methods compared were Hargreaves [Hargreaves, G.H., 1994. Simplified coefficients for estimating monthly solar radiation in North America and Europe. Dept. Paper, Dept. Biol. and Irrig. Eng., Utah State Univ., Logan, Utah], Annandale et al. [Annandale, J.G., Jovanovic, N.Z., Benadé, N., Allen, R.G., 2002. Software for missing data error analysis of Penman-Monteith reference evapotranspiration. Irrig. Sci. 21, 57-67], Allen [Allen, R.G., 1995. Evaluation of procedures for estimating mean monthly solar radiation from air temperature. Rep., Food and Agriculture Organization of the United Nations (FAO), Rome, Italy], Samani [Samani, Z., 2000. Estimating solar radiation and evapotranspiration using minimum climatological data. J. Irrig. Drain. Eng., ASCE, 126(4), 265-267], Allen [Allen, R.G., 1997. Self-calibrating method for estimating solar radiation from air temperature. J. Hydrol. Eng., ASCE, 2 (2), 56-67], and Bristow and Campbell [Bristow, K.L., Campbell, G.S., 1984. On the relationship between incoming solar radiation and daily maximum and minimum temperature. Agric. Forest Meteorol., 31, 159-166]. The estimated R s values were then compared to measured R s (or R s estimated from measured sunshine hours with locally calibrated Ångström coefficients), to check the suitability of these methods under Indian conditions. Three statistical indicators were used for comparing the performances of different methods, namely, modelling efficiency (ME), coefficient of residual mass (CRM), and root mean squared error (RMSE) expressed as a percentage of the arithmetic mean of observed values. To understand the effect of R s estimation on reference evapotranspiration, ET?, the internationally accepted FAO-Irrigation and Drainage Paper 56 Penman-Monteith based method (Allen et al. [Allen, R.G., Pereira, L.S., Raes, D., Smith, M., 1998. Crop evapotranspiration--guidelines for computing crop water requirements. Irrig. and Drain. Paper 56, Food and Agriculture Organization of the United Nations (FAO), Rome, Italy]), employed using both measured R s and estimated R s, were also compared. The methods performed differently for different stations. In general, the original Hargreaves methods, both with [Annandale, J.G., Jovanovic, N.Z., Benadé, N., Allen, R.G., 2002. Software for missing data error analysis of Penman-Monteith reference evapotranspiration. Irrig. Sci. 21, 57-67] and without [Hargreaves, G.H., 1994. Simplified coefficients for estimating monthly solar radiation in North America and Europe. Dept. Paper, Dept. Biol. and Irrig. Eng., Utah State Univ., Logan, Utah] altitude correction, performed better. The choice of method to obtain R s estimates was found to have a relatively small effect on the resulting ET? estimates. In conclusion, under Indian conditions where no R s measurements are available, the R s estimation methods from air temperature extremes were ranked as (in order of descending suitability): Hargreaves [Hargreaves, G.H., 1994. Simplified coefficients for estimating monthly solar radiation in North America and Europe. Dept. Paper, Dept. Biol. and Irrig. Eng., Utah State Univ., Logan, Utah]>Annandale et al. [Annandale, J.G., Jovanovic, N.Z., Benadé, N., Allen, R.G., 2002. Software for missing data error analysis of Penman-Monteith reference evapotranspiration. Irrig. Sci. 21, 57-67]>Samani [Samani, Z., 2000. Estimating solar radiation and evapotranspiration using minimum climatological data. J. Irrig. Drain. Eng., ASCE, 126(4), 265-267]>Allen [Allen, R.G., 1995. Evaluation of procedures for estimating mean monthly solar radiation from air temperature. Rep., Food and Agriculture Organization

Bandyopadhyay A; Bhadra A; Raghuwanshi NS; Singh R

2008-10-01

 
 
 
 
21

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)

2000-01-01

22

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

23

Difference Between IR Radiation Spectra of Ethanol in Free Diffusion Combustion Regime and Regime Influenced by an Air Flow in Modeling of a Fire Tornado  

Science.gov (United States)

Results of experimental investigations of liquid fuel combustion in the regime of a twisted jet (model of a fire tornado) are presented. Flame radiation spectra were registered. In the chosen spectral range of registration (2.2-4.8 ?m), six spectral intervals were clearly traced in which the main portion of radiated energy was concentrated. Using the ratio of the sums of spectral intensities in the vicinities of the 6th and 3rd maxima, we successfully distinguished the regimes of modeled fire tornado and free diffusion fuel combustion.

Sherstobitov, M. V.; Tsvyk, R. Sh.

2013-06-01

24

Air pollution modeling and its application II  

Energy Technology Data Exchange (ETDEWEB)

The main topic of this international meeting was physical-chemical reactions in plumes. Other topics were: air trajectory models for air pollution transport, advanced mathematical techniques in air pollution modeling, evaluation of model performance in practical applications and studies in the field of air pollution modeling.

Wispelaere, C. de (ed.)

1983-01-01

25

Air-quality-model update  

Energy Technology Data Exchange (ETDEWEB)

The Livermore Regional Air Quality Model (LIRAQ) has been updated and improved. This report describes the changes that have been made in chemistry, species treatment, and boundary conditions. The results of smog chamber simulations that were used to verify the chemistry as well as simulations of the entire air quality model for two prototype days in the Bay Area are reported. The results for the prototype day simulations are preliminary due to the need for improvement in meteorology fields, but they show the dependence and sensitivity of high hour ozone to changes in selected boundary and initial conditions.

Penner, J.E.; Walton, J.J.

1982-01-15

26

Macroscopic model of radio emission from extensive air showers  

Science.gov (United States)

A macroscopic model of radio emission from extensive air showers is developed. This model is appropriate for calculating this radio emission at frequencies below 100 MHz. It is constructed on the basis of an analysis of the radiation integral and is verified by comparing field observables predicted by the model with the respective results obtained within the microscopic approach to calculating radio emission from extensive air showers.

Kalmykov, N. N.; Konstantinov, A. A.

2011-07-01

27

Macroscopic model of radio emission from extensive air showers  

Energy Technology Data Exchange (ETDEWEB)

A macroscopic model of radio emission from extensive air showers is developed. This model is appropriate for calculating this radio emission at frequencies below 100 MHz. It is constructed on the basis of an analysis of the radiation integral and is verified by comparing field observables predicted by the model with the respective results obtained within the microscopic approach to calculating radio emission from extensive air showers.

Kalmykov, N. N., E-mail: kalm@eas.sinp.msu.ru; Konstantinov, A. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2011-07-15

28

Macroscopic model of radio emission from extensive air showers  

International Nuclear Information System (INIS)

A macroscopic model of radio emission from extensive air showers is developed. This model is appropriate for calculating this radio emission at frequencies below 100 MHz. It is constructed on the basis of an analysis of the radiation integral and is verified by comparing field observables predicted by the model with the respective results obtained within the microscopic approach to calculating radio emission from extensive air showers.

2011-01-01

29

Air Conditioner Compressor Performance Model  

Energy Technology Data Exchange (ETDEWEB)

During the past three years, the Western Electricity Coordinating Council (WECC) Load Modeling Task Force (LMTF) has led the effort to develop the new modeling approach. As part of this effort, the Bonneville Power Administration (BPA), Southern California Edison (SCE), and Electric Power Research Institute (EPRI) Solutions tested 27 residential air-conditioning units to assess their response to delayed voltage recovery transients. After completing these tests, different modeling approaches were proposed, among them a performance modeling approach that proved to be one of the three favored for its simplicity and ability to recreate different SVR events satisfactorily. Funded by the California Energy Commission (CEC) under its load modeling project, researchers at Pacific Northwest National Laboratory (PNNL) led the follow-on task to analyze the motor testing data to derive the parameters needed to develop a performance models for the single-phase air-conditioning (SPAC) unit. To derive the performance model, PNNL researchers first used the motor voltage and frequency ramping test data to obtain the real (P) and reactive (Q) power versus voltage (V) and frequency (f) curves. Then, curve fitting was used to develop the P-V, Q-V, P-f, and Q-f relationships for motor running and stalling states. The resulting performance model ignores the dynamic response of the air-conditioning motor. Because the inertia of the air-conditioning motor is very small (H<0.05), the motor reaches from one steady state to another in a few cycles. So, the performance model is a fair representation of the motor behaviors in both running and stalling states.

Lu, Ning; Xie, YuLong; Huang, Zhenyu

2008-09-05

30

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

UK PubMed Central (United Kingdom)

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.

Stuber N; Forster P; Rädel G; Shine K

2006-06-01

31

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

32

Inner radiation field modeling using multipole moments  

Energy Technology Data Exchange (ETDEWEB)

In this work we extend the use of multipole moments expansion to the case of inner radiation fields. A series expansion of the photon flux was established. The main advantage of this approach is that it offers the opportunity to treat both inner and external radiation field cases. We determined the expression of the inner multipole moments in both spherical harmonics and in cartesian coordinates. As an application we applied the analytical model to a radiation facility used for small target irradiation. Theoretical, experimental and simulation studies were performed, in air and in a product, and good agreement was reached.

Loussaief, A. [Departement de Physique, Faculte des Sciences de Tunis, El-Manar 2092 (Tunisia); Centre National des Sciences et Technologies Nucleaires, Technopole de Sidi-Thabet 2020 (Tunisia); Mannai, K. [Departement de Physique, Faculte des Sciences de Tunis, El-Manar 2092 (Tunisia); Trabelsi, A. [Departement de Physique, Faculte des Sciences de Tunis, El-Manar 2092 (Tunisia) and Centre National des Sciences et Technologies Nucleaires, Technopole de Sidi-Thabet 2020 (Tunisia)]. E-mail: adel.trabelsi@cern.ch; Baccari, B. [Departement de Physique, Faculte des Sciences de Tunis, El-Manar 2092 (Tunisia)

2007-06-15

33

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.

Mihaiella CRETU; Marius DEACONU

2012-01-01

34

Ion formation in air by ionizing radiation  

International Nuclear Information System (INIS)

[en] The production rates for positive and negative ions from the principal and minor constituents of air - N2, O2, CO2 H2O and Ar - due to electron-impact ionization and dissociative attachment are determined using a calculated electron distribution function resulting from excitation of air by high energy electrons

1993-01-01

35

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

36

Modelling radiation spectrum of a discharge with two liquid non-metallic (tap-water) electrodes in air at atmospheric pressure  

International Nuclear Information System (INIS)

The emission spectra of a column of a direct-current discharge in open air which is performed between two tap-water electrodes (two tap-water flows) are studied in the 240-450 nm spectral range. A comparison of the values of spectral emissivities is made between experimental spectra and the calculated spectra. The emission spectrum calculation is made for four molecules, N2, O2, NO and OH that are present in air plasma. The first part of this paper focuses on building the spectra calculation; the required data are detailed. In the second part, rotational, vibrational and excitational temperatures are determined with the Boltzmann distribution assumed on the quantum states. For that purpose, a comparison of the modelled spectra and the experimental spectra is made in the different parts of the discharge column.

2011-09-21

37

Air Temperature estimation from Land Surface temperature and solar Radiation parameters  

Science.gov (United States)

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

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

2013-04-01

38

Radiation exposure during air and ground transportation  

International Nuclear Information System (INIS)

The results of a one year study program of radiation exposure experienced on both domestic and international flights of the China Airline and the Far East Airline in the Pacific, Southeast Asia and Taiwan areas and on trains and buses on Taiwan island are reported. CaSO4:Dy thermoluminescent dosimeters were used. It has been shown that transit exposures may amount to 10 times that on the ground with an altitude varying from 3,050 to 12,200 m. (U.K.).

1976-01-01

39

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

40

Thermal simulation model for radiators  

Energy Technology Data Exchange (ETDEWEB)

A thermal simulation model for hot water radiators is presented and its possible uses are examined. A comparison is also reported of results obtained by application of the model, with experimental data of thermal emission in steady and dynamic conditions to a radiator tested in the climatic chamber of the Department of Energy Studies of the Polytechnic of Turin, Italy. A flow-chart and the Fortran code of the model are included.

Arneodo, P.; Borchiellini, R.; Mazza, A. (Politecnico di Torino (Italy). Dipt. di Energetica)

1990-12-01

 
 
 
 
41

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

2013-01-01

42

Cosmic radiation doses in commercial air travel  

International Nuclear Information System (INIS)

Sensitivity of both detectors are 0.01 ?Sv/h for gamma rays and 3 bubbles /?Sv for neutrons, satisfactory for the in-flight measurements. Calibration of both detectors are conducted on ground using reference sources of high-energy gamma and neutrons. The measurements are carried out in all commercial flights served by the Eva Air and China Airline; the flight pattern of initial and final ascending/descending, cruising, and landing approach are logged on-line, while the in-flight doses are recorded in cumulative modes Typical result is 42 ± 3 ?Sv for Taipei-NYC flight route, to which the neutrons contribute more than 50% of the total cosmic doses. Annual dose for crew members can be assessed by the measured data and the information of their flight-hours, aircraft types, flight routes, and flight pattern. The annual doses for crew-members are 108 ?Sv for domestic service and up to 7200 ?Sv for international service. (author).

1996-01-01

43

Propagation speed of ?-radiation in air  

International Nuclear Information System (INIS)

[en] 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

44

Preclinical models in radiation oncology  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract As the incidence of cancer continues to rise, the use of radiotherapy has emerged as a leading treatment modality. Preclinical models in radiation oncology are essential tools for cancer research and therapeutics. Various model systems have been used to test radiation therapy, including in vitro cell culture assays as well as in vivo ectopic and orthotopic xenograft models. This review aims to describe such models, their advantages and disadvantages, particularly as they have been employed in the discovery of molecular targets for tumor radiosensitization. Ultimately, any model system must be judged by its utility in developing more effective cancer therapies, which is in turn dependent on its ability to simulate the biology of tumors as they exist in situ. Although every model has its limitations, each has played a significant role in preclinical testing. Continued advances in preclinical models will allow for the identification and application of targets for radiation in the clinic.

Kahn Jenna; Tofilon Philip J; Camphausen Kevin

2012-01-01

45

Radiative fluxes in the troposphere from upper air meteorological data in Saudi Arabia  

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to use the empirical type of parameterization scheme for the calculations of solar radiative fluxes and atmospheric heating or cooling rates in the troposphere by using observed upper air meteorological data. This type of parameterization scheme is useful in calculating the upper air heating/cooling rate for use in planetary boundary layer modeling and in the evaluation of the surface heat budget equation. The results presented in this paper are based on the upper air data collected between 1300 to 1500 Local Standard Time (LST) in Dhahran for the year 1989. The diurnal variation of vertical profiles of radiative fluxes and heating/cooling rates is calculated by changing the solar zenith angle. The diurnal variation of annually averaged solar radiation fluxes reaching the ground is compared with the observed values of solar radiative flux at Dhahran. The calculated values are in excellent agreement with the observed values in the morning and evening times. The scheme used in this paper can be used for obtaining solar radiative fluxes and atmospheric heating or cooling rates above the earth's surface at places where only upper air meteorological data is available.

Rehman, S.; Husain, T.; Halawani, T.O. (King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia))

1992-07-01

46

Models of diffuse solar radiation  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-04-15

47

Air pollution model for point source  

Directory of Open Access Journals (Sweden)

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

Viliam Carach; Jozef Ma?ala

2006-01-01

48

Air pollution model for point source  

International Nuclear Information System (INIS)

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

2006-01-01

49

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

CERN Multimedia

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

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

2012-01-01

50

Overview of Air Force radiation effects programs in fibre optics  

Energy Technology Data Exchange (ETDEWEB)

The requirement for developing military systems which are insensitive to nuclear and electromagnetic (EM) radiation effects has been greatly advanced using fibre optic technology. While optical fibres do not exhibit sensitivity to EM fields, exposure to nuclear fields does result in various adverse response phenomena. These phenomena have prompted a systematic investigation of fibre optic nuclear radiation effects by several Air Force Laboratories. The paper discusses these results from a perspective of historical events and by experiments which have influenced incorporation of fibre optics into military inventories. New directions and programs involving space experiments in fibre optics, guided wave and integrated optic technologies are also presented and the role of fibre optics in an in-situ space radiation environment is discussed.

Taylor, E.W.

1987-06-01

51

Overview of Air Force radiation effects programs in fibre optics  

International Nuclear Information System (INIS)

The requirement for developing military systems which are insensitive to nuclear and electromagnetic (EM) radiation effects has been greatly advanced using fibre optic technology. While optical fibres do not exhibit sensitivity to EM fields, exposure to nuclear fields does result in various adverse response phenomena. These phenomena have prompted a systematic investigation of fibre optic nuclear radiation effects by several Air Force Laboratories. The paper discusses these results from a perspective of historical events and by experiments which have influenced incorporation of fibre optics into military inventories. New directions and programs involving space experiments in fibre optics, guided wave and integrated optic technologies are also presented and the role of fibre optics in an in-situ space radiation environment is discussed. (author).

1987-01-01

52

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

53

Radiation doses arising from the air transport of radioactive materials  

International Nuclear Information System (INIS)

[en] There is a compelling need for the transport of radioactive material by air because of the requirement by hospitals throughout the world for urgent delivery for medical purposes. Many countries have no radionuclide-producing capabilities and depend on imports: a range of such products is supplied from the United Kingdom. Many of these are short lived, which explains the need for urgent delivery. The only satisfactory method of delivery on a particular day to a particular destination is often by the use of scheduled passenger air service. The International Civil Aviation Organization's Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO 1987-1988), prescribe the detailed requirements applicable to the international transport of dangerous goods by air. Radioactive materials are required to be separated from persons and from undeveloped photographic films or plates: minimum distances as a function of the total sum of transport indexes are given in the Instructions. A study, which included the measurement and assessment of the radiation doses resulting from the transport of radioactive materials by air from the UK, has been performed by the National Radiological Protection Board (NRPB) on behalf of the Civil Aviation Authority (CAA) and the Department of Transport (DTp)

1989-01-01

54

Air ionization induced by krypton - 85 beta radiation  

International Nuclear Information System (INIS)

Nuclear fuel industry releases into the environment a wide range of radioactive substances. The long-lived ones are accumulating in the atmosphere, thus, creating a real threat to human beings directly or through changes in global climate. This paper describes the results of laboratory experiments performed with the aim of estimating the effect of Krypton-85 beta radiation on the formation of small air ions. It has been shown that the concentration of small air ions within an experimental chamber depends on the presence of chemical admixtures in the air. The ionic current increased by 10% when SO2 concentration was changed from 0 to 20 g*m-3. In the presence of Krypton-85 (radioactivity of (4.6±0.5)*106 Bq*m-3) this increase was as high as 30%. The newly obtained experimental results were incorporated into theoretical calculations to estimate the ionization power, the mean annual concentration of small air ions, and the density of the ionic current in the air of the environment of a nuclear fuel reprocessing plants. (author)

1997-01-01

55

Priliminary Modeling of Air Breakdown with the ICEPIC code  

CERN Document Server

Interest in air breakdown phenomena has recently been re-kindled with the advent of advanced virtual prototyping of radio frequency (RF) sources for use in high power microwave (HPM) weapons technology. Air breakdown phenomena are of interest because the formation of a plasma layer at the aperture of an RF source decreases the transmitted power to the target, and in some cases can cause significant reflection of RF radiation. Understanding the mechanisms behind the formation of such plasma layers will aid in the development of maximally effective sources. This paper begins with some of the basic theory behind air breakdown, and describes two independent approaches to modeling the formation of plasmas, the dielectric fluid model and the Particle in Cell (PIC) approach. Finally we present the results of preliminary studies in numerical modeling and simulation of breakdown.

Schulz, A E; Cartwright, K L; Mardahl, P J; Peterkin, R E; Bruner, N; Genoni, T; Hughes, T P; Welch, D

2004-01-01

56

Kerma-in air measurement and conversion coefficients to dose due to the environmental gamma radiation  

International Nuclear Information System (INIS)

This work aims to establish a calibration methodology for HPGe detectors calibration methodology, for in situ gamma measurements for air kerma due to environmental radiation exposure and to establish a procedure for the determination of dose applied to environmental gamma exposure based on the air kerma energy distribution and conversion coefficients from kerma to age-dependent dose. It was developed a methodology for characterization of HPGe detector by Monte Carlo calculation based on the EGS4 computer code. The calibration parameters were determined for detectors to be used in in situ gamma spectrometry to determine the air kerma. It has been calculated, also by Monte Carlo calculation, conversion coefficients from air kerma to effective dose and dose in organs and tissues to an exposure from a infinite plane source for several age groups. The ADAM code, developed for the simulation of an adult, was modified in order to accommodate the several anthropomorphic mathematical models with varying age and both sex. (author)

1999-01-01

57

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-03-01

58

Lean hydrogen-air-steam mixture combustion models  

International Nuclear Information System (INIS)

[en] 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

1982-01-01

59

Air Tightness of US Homes: Model Development  

Energy Technology Data Exchange (ETDEWEB)

Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses that database to develop a model for estimating air leakage as a function of climate, building age, floor area, building height, floor type, energy-efficiency and low-income designations. The model developed can be used to estimate the leakage distribution of populations of houses.

Sherman, Max H.

2006-05-01

60

Radiation modeling with direct simulation Monte Carlo  

Science.gov (United States)

Improvements in the modeling of radiation in low density shock waves with direct simulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determine the relaxation collision numbers for excitation of electronic states is proposed. This scheme attempts to move the DSMC programs toward a more detailed modeling of the physics and more reliance on available experimental data. The new method is compared with the current modeling technique and both techniques are compared with available data. The differences in the results are evaluated. The test case is based on an AVCO-Everett shock tube experiment, a 10-km/s standing shock wave in air at 0.1 Torr. The new method agrees with the available data as well as the results from the earlier scheme and is more easily extrapolated to different flow conditions.

Carlson, Ann B.; Hassan, H. A.

1991-06-01

 
 
 
 
61

Validation of the community radiative transfer model  

International Nuclear Information System (INIS)

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

2011-01-01

62

Air pollution modeling and its application VIII  

Energy Technology Data Exchange (ETDEWEB)

The eighteenth International Technical Meeting on Air Pollution Modelling and its application was held in Vancouver, Canada. 103 papers were presented in 5 sessions, and the subject was divided as follows: model assessment and policy implications; regional acid deposition and oxidant modelling; regional scale modelling; global scale dispersion studies including sub-grid scale parameterization of transport and exchange processes; accidental releases including radioactivity and dense gas dispersion; and new developments in dispersion modelling and theory. Two papers are abstracted separately.

van Dop, H.; Steyn, D.G. (eds.) (World Meteorological Organization, Geneva (Switzerland))

1991-01-01

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; Walangkana NA PHATTHALUNG; Yutthana TIRAWANICHAKUL

2008-01-01

64

EXAMPLES OF RADIATION SHIELDING MODELS  

Energy Technology Data Exchange (ETDEWEB)

The attached pictures are examples of shielding models used by WSMS. The models were used in shielding evaluations for Tank 50 pump replacement. They show the relative location of shielding to radiation sources for pumps and pipes. None of the calculations that were associated with these models involved UCNI. The last page contains two pictures from a shielding calculation for the saltstone area. The upper picture is a conceptual drawing. The lower picture is an image copied from the website of a supplier for the project.

Willison, J

2006-07-27

65

Radiation Modeling With Direct Simulation Monte Carlo  

UK PubMed Central (United Kingdom)

Improvements in the modeling of radiation in low density shock waves with directsimulation Monte Carlo (DSMC) are the subject of this study. A new scheme to determinethe relaxation collision numbers for excitation of electronic states is proposed. This schemeattempts to move the DSMC programs toward a more detailed modeling of the physicsand more reliance on available rate data. The new method is compared with the currentmodeling technique and both techniques are compared with available experimental data.The differences in the results are evaluated. The test case is based on experimentalmeasurements from the AVCO-Everett Research Laboratory electric arc-driven shock tubeof a normal shock wave in air at 10 km/s and .1 Torr. The new method agrees with theavailable data as well as the results from the earlier scheme and is more easily extrapolatedto different flow conditions.Nomenclature* Aerospace Engineer, MS 366, Aerothermodynamics Branch, Space Systems Division,NASA-LARC,...

Ann B. Carlson; H. A. Hassan

66

Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) geometries calculated from different UV/visible radiative transfer models  

Directory of Open Access Journals (Sweden)

Full Text Available The results of a comparison exercise of radiative transfer models (RTM) of various international research groups for Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) viewing geometry are presented. Besides the assessment of the agreement between the different models, a second focus of the comparison was the systematic investigation of the sensitivity of the MAX-DOAS technique under various viewing geometries and aerosol conditions. In contrast to previous comparison exercises, box-air-mass-factors (box-AMFs) for different atmospheric height layers were modelled, which describe the sensitivity of the measurements as a function of altitude. In addition, radiances were calculated allowing the identification of potential errors, which might be overlooked if only AMFs are compared. Accurate modelling of radiances is also a prerequisite for the correct interpretation of satellite observations, for which the received radiance can strongly vary across the large ground pixels, and might be also important for the retrieval of aerosol properties as a future application of MAX-DOAS. The comparison exercises included different wavelengths and atmospheric scenarios (with and without aerosols). The strong and systematic influence of aerosol scattering indicates that from MAX-DOAS observations also information on atmospheric aerosols can be retrieved. During the various iterations of the exercises, the results from all models showed a substantial convergence, and the final data sets agreed for most cases within about 5%. Larger deviations were found for cases with low atmospheric optical depth, for which the photon path lengths along the line of sight of the instrument can become very large. The differences occurred between models including full spherical geometry and those using only plane parallel approximation indicating that the correct treatment of the Earth's sphericity becomes indispensable. The modelled box-AMFs constitute an universal data base for the calculation of arbitrary (total) AMFs by simple convolution with a given trace gas concentration profile. Together with the modelled radiances and the specified settings for the various exercises, they can serve as test cases for future RTM developments.

T. Wagner; J. P. Burrows; T. Deutschmann; B. Dix; C. von Friedeburg; U. Frieß; F. Hendrick; K.-P. Heue; H. Irie; H. Iwabuchi; Y. Kanaya; J. Keller; C. A. McLinden; H. Oetjen; E. Palazzi; A. Petritoli; U. Platt; O. Postylyakov; J. Pukite; A. Richter; M. van Roozendael; A. Rozanov; V. Rozanov; R. Sinreich; S. Sanghavi; F. Wittrock

2007-01-01

67

Modelling of air pollution - its use and limitations  

Energy Technology Data Exchange (ETDEWEB)

The article offers a different perspective on modelling for air pollutants and has been written in response to Dr. Middleton's article, Discourse on Air Quality Modelling, carried in Clean Air, No. 6, 1997. (Author)

Scorer, R.S. [Imperial Coll., London (United Kingdom)

1998-06-01

68

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

69

Radiative and turbulent heating rates in the clear-air boundary layer  

Science.gov (United States)

The diurnal evolution of a clear-sky midlatitude summertime boundary layer (BL) was studied using a column model over smooth and homogeneous land, subject to weak, moderate, and strong winds. The high-resolution BL model (lowest point at 30 cm) was equipped with an adequate turbulence scheme and a narrow-band long-wave (LW) radiation scheme, the latter validated using data from the International Comparison of Radiation Codes in Climate Models (ICRCCM).In off-line ICRCCM experiments, ground emissivity ? NBL) is dominated by turbulent cooling, while the upper and lower NBL is dominated by LW cooling. Below about 1 m, a fourth layer is formed with LW warming and turbulent cooling, in agreement with the off-line experiments. When the surface winds fall below about 1 1.5 m s -1 LW cooling dominates in the whole NBL, except very near the surface. In these light wind conditions the Monin Obukhov theory should be revised to include radiative effects.In clear-air daytime conditions strong convective BL heating dominates over weak LW cooling except at 1 3 m heights where the cooler air absorbs the thermal emission of the hot ground. The subsequent LW warming of the superadiabatic surface layer appears to be strong enough to induce local turbulent cooling (despite the hot surface) in an 'hour glass' pattern independently of wind speed, such that the total diabatic heating rate remains nearly constant with height.

Savijärvi, Hannu

2006-01-01

70

Modeling Forest Responses to Air Pollution: Discussion Summary.  

Science.gov (United States)

The discussion session outlined three required elements of any approach to modeling forest responses to air pollution: deposition models, models of primary plant responses to air pollutants, and models to translate those responses into altered patterns of...

P. J. Hanson

1988-01-01

71

Air pollution modelling in Cape Town  

Energy Technology Data Exchange (ETDEWEB)

The degradation of air quality in the modern metropolitan areas has dictated the need to regulate the environmental effects of energy usage. In South Africa, the Atmospheric Pollution Prevention Act No. 45 of 1965 assisted in setting the basis for air-pollution control policies. An air pollution control programme, initiated in Cape Town in 1968, resulted in great improvement in the measured concentrations. Dispersion models provide the capability of assessing the effect of pollution control policies on ambient air quality. This presentation describes work carried out on a comparison of measured pollution levels in Greater Cape Town (GCT) with that predicted using an EPA environmental model. The chosen model for this study was the Industrial Source Complex Short Term 2 (ISCST2). Due allowance has to be made for the topographical complexity of the region, and the model is accepted as being applicable to certain areas under given meteorological conditions. The model`s accuracy is assessed with the use of available hourly SO{sub 2} concentrations, at three monitoring stations in the area and under different meteorological conditions

Dracoulides, D.A.; Dutkiewicz, R.K. [Cape Town Univ. (South Africa)

1995-12-31

72

Air pollution modeling and its application VIII  

Energy Technology Data Exchange (ETDEWEB)

This book is the Proceedings of the Eighteenth NATO/CCMS International Technical Meeting on Air Pollution Modeling, which was held 13-17 May 1990 in Vancouver, British Columbia, Canada. This meeting was the eighth in the series; it specifically addressed modeling applications. The proceedings contains 88 of the 103 papers that were presented at the meeting. They are grouped into six topical areas: model assessment and policy implication; regional acid deposition and oxidant modeling; regional scale modeling; global scale dispersion studies, including sub-grid scale parameterization of transport and exchange processes; accidental releases, including radioactivity and dense gas dispersion; and new developments in dispersion modeling and theory.

Van Dop, H.; Steyn, D.G.

1991-01-01

73

Modelling of indoor air quality; Modellering af indeluftkvalitet  

Energy Technology Data Exchange (ETDEWEB)

The purpose was to develop a simple small-scale method to quantify emissions of air pollution from materials in sensory terms and to establish a model predicting the perceived air quality in a space during steady-state conditions. The effect of concentration on the emission rate from rubber flooring was determined at varied concentrations in a test chamber by varying the quantity of the material at a maintained ventilation rate. The emission rate decreased at increasing concentrations in the air, but at concentrations of relevance to the indoor climate, the emission rate will be approximately constant and independent of the concentration in the air. The required air flow was determined using a trained sensory panel which assessed the perceived air quality in six diffusers at different air flows but at the same concentration of 2-propanone. An air flow of 0.6 l/s or more is required to avoid the polluted air flow through the diffuser being diluted with the surrounding air. The effect of the air velocity on the sensory emission rate was investigated by a sensory panel to assess the quality of air polluted by emission from rubber flooring, carpeting and chip board at two air velocity levels above these materials. A simple small-scale method is recommended to quantify emissions from materials in sensory and chemical terms. It is based on experiments performed in a test chamber from which exhaust is lead through a dilution system to two diffusers. The concentration of air pollutants at the diffusers can be varied so that air quality at two concentrations relevant to the indoor climate can be assessed. (EG) 48 refs.

Knudsen, H. N.

1994-04-01

74

An atmospheric model for computing solar radiation  

Energy Technology Data Exchange (ETDEWEB)

We have modified the model described by King and Buckius [Solar Energy 22, 297 (1979)] in order to determine daily total irradiation [psi][sub GN][sup *] on a horizontal surface on the ground, taking into account albedo effects, for sunny or cloudy days. Calculations of radiation integrated throughout the day as a function of sunshine duration on S and of classical parameters : air mass m, thickness of precipitable water W and Angstrom turbidity coefficient [beta], were made. These parameters are linked, respectively, to measured atmospheric properties such as pressure, dew temperature and horizontal visibility. Calculations were made for one year (1981) using meteorological data from Dakar-Yoff airport and results are compared with daily irradiation measured, for the same period, at Dakar-Hann (C.E.R.E.R.). A quite good agreement is obtained for most of the days of the year. (author)

Bashahu, M. (Universite Nationale du Rwanda, Butare (Rwanda). Faculte des Sciences); Laplaze, D. (Laboratoire des Semi-conducteurs et d' Energie Solaire, Dakar (Senegal))

1994-01-01

75

Dose factors to calculate the radiation exposure due to radioactive waste air from nuclear facilities  

International Nuclear Information System (INIS)

An evaluation of the environmental impact of nuclear plants according to paragraph 45 of the Radiation Protection Directive of the Federal Republic of Germany requires the calculation of dose conversion factors indicating the correlation between the contaminated medium and individual radiation exposure. The present study is to be conceived as a contribution to discussion on this subject. For the determination of radiation exposure caused by the waste air of nuclear plants, models are being specified for computing the dose conversion factors for the external exposure pathways of ?-submersion, ?-submersion and ?-radiation from contaminated ground as well as the internal exposure pathways of inhalation and ingestion, which further elaborate and improve the models previously applied, especially as far as the ingestion pathway is concerned, which distinguishes between 6 major food categories. The computer models are applied to those radionuclides which are significan for nuclear emitters, in particular nuclear light-water power stations. The results obtained for the individual exposure pathways and affected organs are specified in the form of tables. For this purpose, calculations were first of all carried out for the so-called 'reference man'. The results can be transferred to population groups with different consumption habits (e.g. vegetarians) by the application of correction factors. The models are capable of beth a view to covering other age groups. (orig.).

1977-01-01

76

A Neural Network Based Intelligent Predictive Sensor for Cloudiness, Solar Radiation and Air Temperature  

Directory of Open Access Journals (Sweden)

Full Text Available Accurate measurements of global solar radiation and atmospheric temperature,as well as the availability of the predictions of their evolution over time, are importantfor different areas of applications, such as agriculture, renewable energy and energymanagement, or thermal comfort in buildings. For this reason, an intelligent, light-weightand portable sensor was developed, using artificial neural network models as the time-seriespredictor mechanisms. These have been identified with the aid of a procedure based on themulti-objective genetic algorithm. As cloudiness is the most significant factor affecting thesolar radiation reaching a particular location on the Earth surface, it has great impact on theperformance of predictive solar radiation models for that location. This work also representsone step towards the improvement of such models by using ground-to-sky hemisphericalcolour digital images as a means to estimate cloudiness by the fraction of visible skycorresponding to clouds and to clear sky. The implementation of predictive models inthe prototype has been validated and the system is able to function reliably, providingmeasurements and four-hour forecasts of cloudiness, solar radiation and air temperature.

Pedro M. Ferreira; João M. Gomes; Igor A. C. Martins; António E. Ruano

2012-01-01

77

Air Quality Modelling and the National Emission Database : Institutional Strengthening of National Air Emission Inventories - CORINAIR  

DEFF Research Database (Denmark)

The project focuses on development of institutional strengthening to be able to carry out national air emission inventories based on the CORINAIR methodology. The present report describes the link between emission inventories and air quality modelling to ensure that the new national air emission inventory is able to take into account the data requirements of air quality models

Jensen, S. S.

2004-01-01

78

Explicit validation of a surface shortwave radiation balance model over snow-covered complex terrain  

Science.gov (United States)

A model that computes the surface radiation balance for all sky conditions in complex terrain is presented. The spatial distribution of direct and diffuse sky radiation is determined from observations of incident global radiation, air temperature, and relative humidity at a single measurement location. Incident radiation under cloudless sky is spatially derived from a parameterization of the atmospheric transmittance. Direct and diffuse sky radiation for all sky conditions are obtained by decomposing the measured global radiation value. Spatial incident radiation values under all atmospheric conditions are computed by adjusting the spatial radiation values obtained from the parametric model with the radiation components obtained from the decomposition model at the measurement site. Topographic influences such as shading are accounted for. The radiosity approach is used to compute anisotropic terrain reflected radiation. Validations of the shortwave radiation balance model are presented in detail for a day with cloudless sky. For a day with overcast sky a first validation is presented. Validation of a section of the horizon line as well as of individual radiation components is performed with high-quality measurements. A new measurement setup was designed to determine terrain reflected radiation. There is good agreement between the measurements and the modeled terrain reflected radiation values as well as with incident radiation values. A comparison of the model with a fully three-dimensional radiative transfer Monte Carlo model is presented. That validation reveals a good agreement between modeled radiation values.

Helbig, N.; Löwe, H.; Mayer, B.; Lehning, M.

2010-09-01

79

Air Quality Response Modeling for Decision Support  

Directory of Open Access Journals (Sweden)

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

Daniel S. Cohan; Sergey L. Napelenok

2011-01-01

80

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

 
 
 
 
81

Air quality modeling in Warsaw Metropolitan Area  

Directory of Open Access Journals (Sweden)

Full Text Available 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. However, due to the complexity of the forecasting system and the required input data, such environmental prognosis and related decisions contain many potential sources of imprecision and uncertainty. The main sources of uncertainty are commonly considered meteorological and emission input data. This paper addresses the problem of emission uncertainty, and impact of this uncertainty on the forecasted air pollution concentrations and adverse health effects. The computational experiment implemented for Warsaw Metropolitan Area, Poland, encompasses one-year forecast with the year 2005 meteorological dataset. The annual mean concentrations of the main urban pollutants are computed. The impact of uncertainty in emission field inventory is also considered. Uncertainty assessment is based on the Monte Carlo technique where the regional scale CALPUFF model is the main forecasting tool used in air quality analysis.

Piotr Holnicki; Zbigniew Nahorski

2013-01-01

82

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

83

Mathematical Models for Room Air Distribution  

DEFF Research Database (Denmark)

A number of different models on the air distribution in rooms are introduced. This includes the throw model, a model on penetration length of a cold wall jet and a model for maximum velocity in the dimensioning of an air distribution system in highly loaded rooms and shows that the amount of heat removed from the room at constant penetration length is proportional to the cube of the velocities in the occupied zone. It is also shown that a large number of diffusers increases the amount of heat which may be removed without affecting the thermal conditions. Control strategies for dual duct and single duct systems are given and the paper is concluded by mentioning a computer-based prediction method which gives the velocity and temperature distribution in the whole room.

Nielsen, Peter V.

1982-01-01

84

Mathematical Models for Room Air Distribution - Addendum  

DEFF Research Database (Denmark)

A number of different models on the air distribution in rooms are introduced. This includes the throw model, a model on penetration length of a cold wall jet and a model for maximum velocity in the dimensioning of an air distribution system in highly loaded rooms and shows that the amount of heat removed from the room at constant penetration length is proportional to the cube of the velocities in the occupied zone. It is also shown that a large number of diffusers increases the amount of heat which may be removed without affecting the thermal conditions. Control strategies for dual duct and single duct systems are given and the paper is concluded by mentioning a computer-based prediction method which gives the velocity and temperature distribution in the whole room.

Nielsen, Peter V.

1982-01-01

85

Empirical models of terrestrial trapped radiation.  

UK PubMed Central (United Kingdom)

A survey of empirical models of particles (electrons, protons and heavier ions) of the Earth's radiation belts developed to date is presented. Results of intercomparison of the different models as well as comparison with experimental data are reported. Aspects of further development of radiation condition modelling in near-Earth space, including dynamic model developing are discussed.

Panasyuk MI

1996-01-01

86

ATR, Radiation Transport Models in Atmosphere at Various Altitudes  

International Nuclear Information System (INIS)

[en] 1 - Description of problem or function: ATR is a user-oriented code for calculating quickly and simply radiation environment problems at all altitudes in the atmosphere. The code is based on parametric models of a comprehensive data base of air transport results which were generated using discrete ordinates transport techniques for infinite homogeneous air. The effects of air-ground interface and non-uniform air density are treated as perturbation corrections on homogeneous air results. ATR includes parametric models for neutrons and secondary gamma rays as a function of space, energy and source- target angle out to angles of 550 g/cm2 of air. ATR contains parameterizations of infinite medium air transport of neutrons and secondary gamma rays and correction factors for the air-ground interface and high altitude exponential air. It responds to a series of user-oriented commands which specify the source, geometry and print options to output a variety of useful air transport information, including energy-angle dependent fluence, dose, current, and isodose ranges. 2 - Method of solution: The version 3 differs from earlier versions in that version 3 contains the parameterization of the new neutron and secondary gamma rays data base that was calculated using the latest DNA approved cross sections for air. Other improvements to the ATR code include: parameterization and inclusion into ATR of new air- over-ground correction factors, low energy x-rays calculations, new fission source, and new convenience options. 3 - Restrictions on the complexity of the problem: ATR takes approximately 36,000 decimal words of storage. This can be lessened by overlaying different parts of the code

1981-01-01

87

Comparison of two diffuse sky radiation models  

Energy Technology Data Exchange (ETDEWEB)

Many models have been developed to predict the diffuse sky solar radiation since the original work of Liu and Jordan. A review of several of the older models and some of the newer models is contained in Duffie and Beckman. The diffuse solar radiation models may be hourly, daily, or monthly models, and are typically based on the measurement of global solar radiation (total solar radiation on a horizontal surface). The other parameter typically used in the model is usually based on extraterrestrial solar radiation on a horizontal surface. Recent models of this type include the Erbs Model, the Orgill-Hollands Model, the Collares-Pereira and Rabl Model, and the Blytheville, AR Model developed by Mujahid and Turner. The Erbs, Orgill-Hollands, and Blytheville Models are hourly models using k /SUB T/ , the ratio of hourly measured global to hourly extraterrestrial solar radiation on a horizontal surface, as a parameter in the model. The Collares-Pereira and Rabl Model is a daily prediction model. Comparisons of several of these models with recorded solar radiation data at Blytheville, AR. are made. Instead of using extraterrestrial solar radiation as a parameter, some models will use some form of clear day global radiation. The Bugler Model, and the Stauter and Klein Model are two recent hourly models which use this approach. Comparisons of the Bugler Model with recorded data from Blytheville, AR, were made in. The Stauter-Klein Model was not compared, however, and the purpose of this technical note is to compare the accuracy of the Stauter-Klein Model with recorded data from Blytheville, AR and to present a slightly different model which better matches the recorded data.

Turner, W.D.; Salim, M.

1984-01-01

88

Multiscale Modeling of Radiation Damage  

International Nuclear Information System (INIS)

Computational simulation is actually a fundamental tool in many areas of knowledge from physics, chemistry, and technology. In particular multiscale modeling is a key step connecting microscopic and macroscopic phenomena, allowing a very deep inside of the observable mechanisms. The application of multiscale simulation modeling to radiation damage in structural materials (mechanical properties) considers different levels of description: quantum-mechanics atomistic description, classical atomic motion (Molecular Dynamics, MD), diffusion and transport of defects in the meso and microscopic scales (Kinetic Monte Carlo/KMC, rate equations), interaction of defects and dislocation (Dislocation Dynamics, DD), and classical continuous laws of mechanics in engineering. The coordinated use of these techniques is described, and results on metals and covalent-bonding materials, arriving to microscopic description using MD and KMC, are presented. The necessary validation of the different steps with experiments is emphasized. (Author) 50 refs.

2000-01-01

89

Possible role of solar radiation on the viability of some air fungi in Egypt.  

UK PubMed Central (United Kingdom)

The high occurrence of Alternaria humicola and the moderate occurrence of Stemphylium verruculosum, Rhizopus nigricans, and Epicoccum nigrum in the air of Egypt could be correlated to their apparent resistance to solar radiation. Cladosporium herbarum, Aspergillus niger, and Penicillium oxalicum, although highly occurring, were light-sensitive. The miniumum solar radiation in November, coupled with the highest total fungal catch, dominated by Cladosporium herbarum, reveals the importance of solar radiation as a factor with direct effect on the air fungal population.

Ali MI; Salama AM; Ali TM

1976-01-01

90

Air pollution modelling and simulation. Proceedings  

Energy Technology Data Exchange (ETDEWEB)

This book collates the written contributions of the Second Conference on Air Pollution Modelling and Simulation (APMS 2001). A wide range of current topics is covered, focusing on three challenging issues: (1) the modelling issue of complex, multiphase, atmospheric chemistry; (2) the numerical issue associated with comprehensive three-dimensional chemistry-transport models; and (3) the key issues of data assimilation and inverse modelling. State-of-the art research is presented with many operational procedures applied at either forecast agencies or companies. (orig.)

Sportisse, B. (ed.) [Ecole National des Ponts et Chaussees, Marne la Vallee Cedex (France)

2002-07-01

91

POLUTE. Forest Air Pollutant Uptake Model  

Energy Technology Data Exchange (ETDEWEB)

POLUTE is a computer model designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used, with only minor changes, for any gaseous pollutant. The model provides an estimate describing the response of the vegetarian-atmosphere system to the environment as related to three types of processes: atmospheric diffusion, diffusion near and inside the absorbing plant, and the physical and chemical processes at the sink on or within the plant.

Murphy, C.E. Jr. [Savannah River Plant, Aiken, SC (United States); Sinclair, T.R. [Cornell University, Ithaca, NY (United States)

1992-02-13

92

Estimating solar radiation for plant simulation models  

Energy Technology Data Exchange (ETDEWEB)

Five algorithms producing daily solar radiation surrogates using daily temperatures and rainfall were evaluated using measured solar radiation data for seven U.S. locations. The algorithms were compared both in terms of accuracy of daily solar radiation estimates and terms of response when used in a plant growth simulation model (CERES-wheat). Requirements for accuracy of solar radiation for plant growth simulation models are discussed. One algorithm is recommended as being best suited for use in these models when neither measured nor satellite estimated solar radiation values are available.

Hodges, T.; French, V.; Leduc, S.

1985-01-01

93

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. 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 fast estimate of cloud radiative forcing, the evaluation of the sensitivity to changes in environmental conditions, and as a tool in education.

T. Corti; T. Peter

2009-01-01

94

A Earth Outgoing Longwave Radiation Climate Model  

Science.gov (United States)

An Earth outgoing longwave radiation (OLWR) climate model has been constructed for radiation budget study. The model consists of the upward radiative transfer parameterization of Thompson and Warren (1982), the cloud cover model of Sherr et al. (1968) and a monthly average climatology defined by the data from Crutcher and Meserve (1971) and Taljaard et al. (1969). Additional required information is provided by the empirical 100mb water vapor mixing ratio equation of Harries (1976), and the mixing ratio interpolation scheme of Briegleb and Ramanathan (1982). Cloud top temperature is adjusted so that the calculation would agree with NOAA scanning radiometer measurements. Both clear sky and cloudy sky cases are calculated and discussed for global average, zonal average and world-wide distributed cases. The results agree well with the satellite observations. The clear sky case shows that the OLWR field is highly modulated by water vapor, especially in the tropics. The strongest longitudinal variation occurs in the tropics. This variation can be mostly explained by the strong water vapor gradient. Although in the zonal average case the tropics have a minimum in OLWR, the minimum is essentially contributed by a few very low flux regions, such as the Amazon, Indonesia and the Congo. There are regions in the tropics such that their OLWR is as large as that of the subtropics. In the high latitudes, where cold air contains less water vapor, OLWR is basically modulated by the surface temperature. Thus, the topographical heat capacity becomes a dominant factor in determining the distribution. Clouds enhance water vapor modulation of OLWR. Tropical clouds have the coldest cloud top temperatures. This again increases the longitudinal variation in the region. However, in the polar region, where temperature inversion is prominent, cloud top temperature is warmer than the surface. Hence, cloud has the effect of increasing OLWR. The implication of this cloud mechanism is that the latitudinal gradient of net radiation is thus further increased, and the forcing of the general atmospheric circulation is substantially different due to the increased additional available energy. The analysis of the results also suggests that to improve the performance of the Budyko-Sellers type energy balance climate model in the tropical region, the parameterization of the longwave cooling should include a water vapor absorbing term.

Yang, Shi-Keng

95

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

Directory of Open Access Journals (Sweden)

Full Text Available We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030) and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030). We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to ?2.00 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2) under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by ?1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing could be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extent be controlled by greenhouse gas emissions. We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations caused by future air pollution mitigation, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time.

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

2008-01-01

96

SCROLL, a superconfiguration collisional radiative model with external radiation  

Energy Technology Data Exchange (ETDEWEB)

A collisional radiative model for calculating non-local thermodynamical-equilibrium (non-LTE) spectra of heavy atoms in hot plasmas has been developed. It takes into account the numerous excited an autoionizing states by using superconfigurations. These are split systematically until the populations converge. The influence of an impinging radiation field has recently been added to the model. The effect can be very important. (author)

Bar-Shalom, A.; Oreg, J. [Nuclear Research Center Negev, Be' er Sheva (Israel); Klapisch, M. [ARTEP, Columbia, MD (United States)

2000-01-01

97

Natural gamma radiation in air versus soil nature in Portugal  

International Nuclear Information System (INIS)

[en] In this work in situ gamma spectrometry is used to correlate natural gamma radiation doses to the predominant type of soils in Portugal. Natural terrestrial gamma radiation has its origin on cosmogenic and primordial nuclides (the uranium and thorium series and 40K). The importance of these nuclides in each type of soil is a consequence of soil formation from the different original rocks. Mechanical, chemical and biochemical processes determine the concentration of the primordial radionuclides present in each type of soil. Former studies of natural gamma radiation provided data on the dose rate in air 1 meter above ground for all administrative regions of Portuguese mainland and allowed the making of the radiological map of Portugal. Some of these points were selected for the present study, representing high, intermediate and low dose rate regions. The characterization of each selected point was performed by the identification of the primordial radionuclides present in the soil, their relative contribution to the dose and final evaluation of the total dose. The relative contributions of 232Th and 238U series and 40K to the dose were calculated after the analysis of the data obtained by in situ gamma spectrometry and yielded: for intrusive rocks 45 ± 7%, 25 ± 6% and 30 ± 5%, respectively for the thorium and uranium series and potassium; for sedimentary rocks 32 ± 5%, 22 ± 4% and 46 ± 5% and for metamorphic rocks 42 ± 8%, 22 ± 9% and 36 ± 13%. The relative contribution to the dose rate was determined and yielded: for intrusive rocks 67 ± 29 nGy.h-1, 37 ± 14 nGy.h-1 and 43 ± 14 nGy.h-1, respectively for the thorium and uranium series and potassium; for sedimentary rocks 12 ± 5 nGy.h-1, 8 ± 2 nGy.h-1 and 17 ± 6 nGy.h-1 and for metamorphic rocks 46 ± 36 nGy.h-1, 25 ± 20 nGy.h-1 and 31 ± 11 nGy.h-1. The ranges of the measured data and the contributions to the total dose rate for each type of soil are mentioned on the full paper. (author)

2000-01-01

98

Mathematical modeling of photochemical air pollution  

Energy Technology Data Exchange (ETDEWEB)

This work presents a mathematical description of the production and transport of photochemical oxidants within an urban airshed. The combined influences of advection, turbulent diffusion, chemical reaction, emissions and surface removal processes are all incorporated into a series of models that are based on the species continuity equations. A delineation of the essential assumptions underlying the formulation of a three-dimensional, a Lagrangian trajectory, a vertically integrated and single cell air quality model is presented. Since each model employs common components and input data the simpler forms can be used for rapid screening calculations and the more complex ones for detailed evaluations. (JMT)

McRae, G.J.

1981-01-01

99

Badminton Projectile Motion: Modeling Air Resistance  

Science.gov (United States)

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

Cox, Anne

2012-06-22

100

Meteorological models and the air pollution simulation  

International Nuclear Information System (INIS)

The atmosphere is the main media to transporting and dispersing the radioactive contaminants in global accidental situations. The possibilities of the air pollution simulation using the meteorological models are studied. This paper presents some possibilities in the VINCA Institute of Nuclear Sciences and Federal Hydrometeorological Institute, Belgrade, for investigations of the environmental impact of chemical and radioactive pollutants released from various power plants and other energy sources. (author)

1998-10-01

 
 
 
 
101

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

102

Validation of five global radiation models with measured daily data in China  

Energy Technology Data Exchange (ETDEWEB)

Two sunshine based and three air temperature based global radiation models are calibrated using daily data in Jan. 1 1994-Dec. 31 1998 at 48 stations all over China. The Nash-Sutcliffe equation (NSE) is used as the model evaluation criterion. The sunshine based models are suitable for daily global radiation estimation. The averaged NSE value of the Angstroem model is 0.83, and the maximum value is 0.91. The maximum NSE value of the Bahel model is 0.92 with an averaged value of 0.84. The models that use air temperature as the input variable are not suitable for daily global radiation estimation in China. The averaged NSE values of the three air temperature based models (Bristow-Campbell model, Allen model and Hargreaves model) are not larger than 0.47. A logarithmic relationship between the daily global radiation/daily extra-terrestrial solar radiation (R{sub G}/R{sub A}) and the temperature difference between the maximum and minimum daily air temperature (T{sub M}-T{sub m}) is found in the present study. A new daily global radiation model that is a function of R{sub A}, sunshine hours and T{sub M}-T{sub m} is designed, which gives an averaged NSE value of 0.85 and a maximum value of 0.92.

Chen Rensheng E-mail: crs2008@ns.lzb.ac.cn; Ersi Kang; Yang Jianping; Lu Shihua; Zhao Wenzhi

2004-07-01

103

Validation of five global radiation models with measured daily data in China  

International Nuclear Information System (INIS)

[en] Two sunshine based and three air temperature based global radiation models are calibrated using daily data in Jan. 1 1994-Dec. 31 1998 at 48 stations all over China. The Nash-Sutcliffe equation (NSE) is used as the model evaluation criterion. The sunshine based models are suitable for daily global radiation estimation. The averaged NSE value of the Angstroem model is 0.83, and the maximum value is 0.91. The maximum NSE value of the Bahel model is 0.92 with an averaged value of 0.84. The models that use air temperature as the input variable are not suitable for daily global radiation estimation in China. The averaged NSE values of the three air temperature based models (Bristow-Campbell model, Allen model and Hargreaves model) are not larger than 0.47. A logarithmic relationship between the daily global radiation/daily extra-terrestrial solar radiation (RG/RA) and the temperature difference between the maximum and minimum daily air temperature (TM-Tm) is found in the present study. A new daily global radiation model that is a function of RA, sunshine hours and TM-Tm is designed, which gives an averaged NSE value of 0.85 and a maximum value of 0.92

2004-01-01

104

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

105

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

106

The impact of micromachined ultrasonic radiators on the efficiency of transducers in air.  

UK PubMed Central (United Kingdom)

The use of micromachined thin-film ultrasonic radiators to improve the efficiency of conventional in-air acoustic transducers is investigated. We conduct a theoretical investigation of the parameters that determine the efficiency of thin-film transducers, using a lumped parameter model, and show that the efficiency can be improved by choosing a radiating plate thickness that can be realized by micromachining. We also identified the problems that should be overcome to design and fabricate a micromachined ultrasonic transducer with the theoretically predicted efficiency. Based on the lumped parameter model, we showed that the problems can be resolved via an appropriate design scheme. A piezoelectric micromachined ultrasonic transducer is designed and fabricated to demonstrate the impact of the proposed design method. Test results for the fabricated radiator indicated that it provided an electroacoustic efficiency of 58.4%, up to 300% greater than either the unit previously fabricated by the authors or conventional unimorph ultrasonic transducers. An array of the proposed transducers was also designed, fabricated, and tested as a source transducer for a parametric array, since transducer efficiency is important for practical applications of a parametric array. The test results for the proposed transducer demonstrate its potential for improving the practicality of parametric array sources, such as parametric loudspeakers and directional ultrasonic ranging sensors.

Je Y; Lee H; Moon W

2013-08-01

107

The impact of micromachined ultrasonic radiators on the efficiency of transducers in air.  

Science.gov (United States)

The use of micromachined thin-film ultrasonic radiators to improve the efficiency of conventional in-air acoustic transducers is investigated. We conduct a theoretical investigation of the parameters that determine the efficiency of thin-film transducers, using a lumped parameter model, and show that the efficiency can be improved by choosing a radiating plate thickness that can be realized by micromachining. We also identified the problems that should be overcome to design and fabricate a micromachined ultrasonic transducer with the theoretically predicted efficiency. Based on the lumped parameter model, we showed that the problems can be resolved via an appropriate design scheme. A piezoelectric micromachined ultrasonic transducer is designed and fabricated to demonstrate the impact of the proposed design method. Test results for the fabricated radiator indicated that it provided an electroacoustic efficiency of 58.4%, up to 300% greater than either the unit previously fabricated by the authors or conventional unimorph ultrasonic transducers. An array of the proposed transducers was also designed, fabricated, and tested as a source transducer for a parametric array, since transducer efficiency is important for practical applications of a parametric array. The test results for the proposed transducer demonstrate its potential for improving the practicality of parametric array sources, such as parametric loudspeakers and directional ultrasonic ranging sensors. PMID:23541961

Je, Yub; Lee, Haksue; Moon, Wonkyu

2013-03-04

108

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

Directory of Open Access Journals (Sweden)

Full Text Available We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030) and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030). We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to ?2.05 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2) under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by ?1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing cloud be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extend be controlled by greenhouse gas emissions. We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations in the future within a realistic range, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time.

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

2008-01-01

109

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; T. Peter

2009-01-01

110

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 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.

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

2013-08-01

111

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

2013-01-01

112

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

DEFF Research Database (Denmark)

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

Yin, Chungen

2013-01-01

113

Daily total global solar radiation modeling from several meteorological data  

Science.gov (United States)

This paper investigates the modeling of the daily total global solar radiation in Adana city of Turkey using multi-linear regression (MLR), multi-nonlinear regression (MNLR) and feed-forward artificial neural network (ANN) methods. Several daily meteorological data, i.e., measured sunshine duration, air temperature and wind speed and date of the year, i.e., monthly and daily, were used as independent variables to the MLR, MNLR and ANN models. In order to determine the relationship between the total global solar radiation and other meteorological data, and also to obtain the best independent variables, the MLR and MNLR analyses were performed with the "Stepwise" method in the Statistical Packages for the Social Sciences (SPSS) program. Thus, various models consisting of the combination of the independent variables were constructed and the best input structure was investigated. The performances of all models in the training and testing data sets were compared with the measured daily global solar radiation values. The obtained results indicated that the ANN method was better than the other methods in modeling daily total global solar radiation. For the ANN model, mean absolute error (MAE), mean absolute percentage error (MAPE), correlation coefficient ( R) and coefficient of determination ( R 2) for the training/testing data set were found to be 0.89/1.00 MJ/m2 day, 7.88/9.23%, 0.9824/0.9751, and 0.9651/0.9508, respectively.

Bilgili, Mehmet; Ozgoren, Muammer

2011-05-01

114

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

115

AIR QUALITY MODELING OF PM AND AIR TOXICS AT NEIGHBORHOOD SCALES  

Science.gov (United States)

The current interest in fine particles and toxics pollutants provide an impetus for extending air quality modeling capability towards improving exposure modeling and assessments. Human exposure models require information on concentration derived from interpolation of observati...

116

Air modeling of industrial area in India  

Energy Technology Data Exchange (ETDEWEB)

With privatization of power sector to fulfill power demand in India, fossil based power projects are proposed at different locations by Indian and foreign companies. As power industry occupies key role in the economic liberalization, the siting and technology for power plant are relevant in the Indian context, and modeling exercise is wanted for the design of stacks and pollution control measures. A case history is included to demonstrate the use of air quality modeling in prediction, and to delineate mitigation measures. Study has been conducted with Gaussian dispersion model to assess the incremental 24 hour maximum Ground Level Concentrations (GLCs) of SO{sub 2}, NO{sub x}, SPM due to proposed power plant. Stack and emission data, wind velocity, wind direction, temperature, mixing height, and stability classes are used as input parameters to the dispersion model. Maximum 24 hour GLCs of SO{sub 2}, NO{sub x}, and SPM are 30, 53, 2.5 {mu}g/m at 2 km east as down wind direction is from west (35%), south-southwest (25%), and west-northwest (15%). Northeast is the most affected quadrant during summer. Plume loopings are assessed from southeast to northeast directions, with maximum concentration in the east with respect to the site. First plume loop is assessed at 2 km distance, and subsequent loops are assessed with less pollutants concentration under atmospheric stability classes (B-E). High concentration of NO{sub x} has been assessed, which may cause hazardous effect like dense fog, particulate droplets, whereas SO{sub 2} concentration may cause acid raining, acid deposition to the surrounding. Proper air pollution control measures are required to minimize NO{sub x} levels.

Kumar, A. [Univ. of Delhi (India)

1996-12-31

117

Comparison of absorbed radiation doses in barium and air enema reduction of intussusception: a phantom study  

Energy Technology Data Exchange (ETDEWEB)

Objective. We assessed the relative radiation load in patients undergoing hydrostatic and pneumatic reduction of childhood intussusception. Materials and methods. In a phantom study we simulated two situations occurring during reduction of intussusception. The absorbed radiation dose was measured at several positions in the phantom using either barium sulphate (BaSO{sub 4}) or air in the simulated reduction, combined with either automatic exposure control (AEC) or constant exposure rate (CER) at fluoroscopy. From these values the mean absorbed dose was calculated for different depth compartments within the phantom. Results. In the barium study the mean absorbed dose averaged over the total irradiated volume was 14-23 % lower when CER was used instead of AEC; in the air study the dose was 35-43 % lower when AEC was used instead of CER. The combination of air and AEC provided the lowest mean absorbed dose in the tissue. The barium enema created a low-radiation zone, which might be utilized for protecting radiation sensitive tissue. Conclusion. The use of BaSO{sub 4} or air in reduction of intussusception requires the proper combination with CER and AEC, respectively, to minimize the radiation load to the patient; the lowest radiation load is obtained by using air and AEC. (orig.). With 1 fig., 3 tabs.

Persliden, J. [Department of Radiation Physics, Faculty of Health Science, Linkoeping University, Linkoeping (Sweden); Schuwert, P. [Hospital Physics, The Karolinska Hospital, Stockholm (Sweden); Mortensson, W. [Department of Pediatric Radiology, The Karolinska Institute, St. Goeran`s Children`s Hospital, Box 12 500, S-112 81 Stockholm (Sweden)

1996-05-01

118

Comparison of absorbed radiation doses in barium and air enema reduction of intussusception: a phantom study  

International Nuclear Information System (INIS)

Objective. We assessed the relative radiation load in patients undergoing hydrostatic and pneumatic reduction of childhood intussusception. Materials and methods. In a phantom study we simulated two situations occurring during reduction of intussusception. The absorbed radiation dose was measured at several positions in the phantom using either barium sulphate (BaSO4) or air in the simulated reduction, combined with either automatic exposure control (AEC) or constant exposure rate (CER) at fluoroscopy. From these values the mean absorbed dose was calculated for different depth compartments within the phantom. Results. In the barium study the mean absorbed dose averaged over the total irradiated volume was 14-23 % lower when CER was used instead of AEC; in the air study the dose was 35-43 % lower when AEC was used instead of CER. The combination of air and AEC provided the lowest mean absorbed dose in the tissue. The barium enema created a low-radiation zone, which might be utilized for protecting radiation sensitive tissue. Conclusion. The use of BaSO4 or air in reduction of intussusception requires the proper combination with CER and AEC, respectively, to minimize the radiation load to the patient; the lowest radiation load is obtained by using air and AEC. (orig.). With 1 fig., 3 tabs.

1996-01-01

119

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

120

3D modeling for air quality equipment  

Energy Technology Data Exchange (ETDEWEB)

Proper performance of equipment such as electrostatic precipitators, bag houses, scrubbers, and continuous emissions monitors in stacks is dependent on having uniform flow and velocities. Due to the short sections of rapidly varying duct configurations leading to such equipment, flow patterns are usually highly skewed unless flow control devices are properly designed and verified. The most reliable method to achieve the desired uniform velocity pattern and low pressure losses is by application of physical, three-dimensional (3D) air flow models. In the selection of the model geometric scale, model boundaries and test flows, sufficient attention must be given to flow similitude considerations, and a relatively larger model than has typically been used may be needed to minimize scale effects and to obtain data representative of field conditions. The model boundary should include enough upstream geometry to properly simulate the approach flow. To be cost effective, extensive quantitative data gathering should be restricted to the final design, while flow visualization and limited measurements are used to evaluate a preliminary design and investigate modifications. Derivation of modifications can be made efficiently if the underlying flow problem is understood, and these usually occur upstream of the section under study.

Hecker, G.E.; Padmanabhan, M.; Weber, F. [Alden Research Lab., Inc., Holden, MA (United States)

1995-09-01

 
 
 
 
121

Radiatively driven convection in marine stratocumulus clouds: Numerical modeling  

Energy Technology Data Exchange (ETDEWEB)

The entrainment of warm dry air from above the inversion into a stratocumulus deck may play an important role in the dissipation of the cloud. A quantitative understanding of radiatively induced convection at cloud top is necessary in order to produce accurate entrainment rates and predictions of the diurnal evolution of a cloud layer. A three dimensional numerical model is used to study such convection. The model has been used extensively to study Rayleigh-Benard convection in an approximate geophysical setting. Here the authors model an idealized, non-sheared, nocturnal marine boundary layer to investigate the development of convection generated by cloud radiative cooling. Cloud forcing rather than surface forcing is investigated.

Norris, P.M.; Rogers, D.P. [Scripps Institution of Oceanography, La Jolla, CA (United States)

1994-12-31

122

Radiative flavour violation in SUSY GUT models  

Energy Technology Data Exchange (ETDEWEB)

Present data show clear evidence for new physics beyond minimal flavour violation in the b{yields} s transition. We discuss radiative sources of flavour violation in the MSSM with boundary conditions from unified theories. We show how a radiatively generated, hierarchical CKM matrix occurs naturally in supersymmetric GUT models and explain the relation between CKM elements and the trilinear SUSY breaking terms A{sub ij}. The model makes predictions for FCNC which can be probed at LHCb.

Bobrowski, Markus; Nierste, Ulrich; Schneider, Moritz [Karlsruher Institut fuer Technologie (KIT), Institut fuer Theoretische Teilchenphysik (Germany)

2011-07-01

123

Solving vertical transport and chemistry in air pollution models  

International Nuclear Information System (INIS)

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

2000-01-01

124

Modelling the regional effects of climate change on air quality  

International Nuclear Information System (INIS)

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

2007-01-01

125

Handbook of anatomical models for radiation dosimetry  

CERN Multimedia

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

126

Radiation/conduction model for multitube AMTEC cells  

Science.gov (United States)

A radiation/conduction model was developed for calculating parasitic heat losses and temperatures in vapor-anode, multitube AMTEC cells. The model accounted for the presence of an internal circumferential radiation shield, and a conduction stud between the hot end of the cell and the BASE tubes support plate. The radiation view factors were calculated using either closed-form algebraic solutions or approximate relations, and all reciprocity and enclosure relations were satisfied. In the integrated cell model, the present thermal model was coupled to a vapor pressure loss model, and an electrochemical and electrical circuit model, using an efficient iterative solution procedure. The integrated cell model predictions were compared with experimental results of PX-4C, PX-5A and PX-3A cells, that were tested in vacuum at the Air Force Research Laboratory. Results illustrated the effects of using a CREARE condenser and a conduction stud, reducing the number of BASE tubes, and changing the size of the cell diameter, on the heat flow and temperatures in the cell, as well as the cell electrical performance parameters.

Tournier, Jean-Michel; El-Genk, Mohamed S.

1998-01-01

127

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.

Yang Gu; James McCalley; Ming Ni; Rui Bo

2013-01-01

128

A simplified model for the calculation of air infiltration  

Energy Technology Data Exchange (ETDEWEB)

The procedure, adopted to obtain a simplified and easy to use model for the calculation of air infiltration in buildings, is described. The model structure is defined by means of the Buckingham theorem; the coefficients are determined using a detailed model. The results are expressed in terms of air flow rate per unit surface.

Fracastoro, G.V.; Pagani, R.

1988-02-01

129

Sensitivity study on air dispersion and hazard exposure models  

Energy Technology Data Exchange (ETDEWEB)

The U.S. Army is currently using mathematical models to assess potential hazards associated with the use of depleted uranium (DU) munitions. These models simulate dispersion of material released to the air, determine subsequent air and ground concentrations, and estimate potential radiological and toxicological exposures to man from such releases. The models provide the Army with a decision-support tool for addressing health and safety considerations associated with depleted uranium released to the air under a range of scheduled or accidental conditions. In Section II the systematic sensitivity analysis used in this study is described. The model parameters and sensitivity/uncertainty evaluation for the air dispersion models and hazard exposure models are discussed in Section III. Section IV contains the conclusions drawn from the evaluation of model parameters from both the air dispersion and hazard exposure models.

Bucci, S.A.; Nalbandian, J.Y.

1981-04-01

130

?????? ?????????????? ?????????? ??????????? ?? ??????? ??????-????????? ??? ?????????????? ??????????? ???? 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. ??????????? ?????? ?????????????????? ??????????? ??????????? ? ???????? ?????? ? ?????????????? ?????? ? ???? ???????????????? ???????????? ??????????? ???????????.

Volodymyr P. Kharchenko; Yuriy V. Chynchenko

2008-01-01

131

On the biological significance of radiation exposure in air transport  

International Nuclear Information System (INIS)

[en] The environmental radiation load is significantly increased at higher altitudes. Unlike terrestrial situations, there is also a sizeable fraction of densely ionising particles, mainly neutrons but also accelerated ions. This paper addresses the question of the biological significance of this radiation field in view of recent recommendations of the International Commission for Radiological Protection (ICRP). It focuses on two aspects: the dose rate dependence of mutation induction with sparsely ionising radiation and mutation induction with heavy ions. Experiments with mammalian cells in culture are summarised and their results compared with the ICRP recommendations. It is concluded that the recently introduced 'dose and dose rate effectiveness factor' has to be viewed with some caution while the new 'quality factor' seems to be essentially in line with the results of cellular investigations. (author)

1993-01-01

132

Dose response of tracheal epithelial cells to ionizing radiation in air-liquid interface cultures  

Energy Technology Data Exchange (ETDEWEB)

The dose-response relationships of tracheal epithelial cells to ionizing radiation was examined in air-liquid interface cultures, which were developed for the purpose of simulating in vivo conditions. The cultures investigated in this study were expected to be advantageous for the performance of irradiation experiments using short-range {alpha} rays. The level of dose response of air-liquid interface cultures to ionizing radiation proved to be the same as that for in vivo conditions. This result indicates that air-liquid interface cultures will prove most useful, to facilitate future studies for the investigation of the biological effects induced in tracheal epithelial cells by ionizing radiation, especially by {alpha}-rays. (orig.)

Fukutsu, K.; Yamada, Y.; Shimo, M. [National Inst. of Radiological Sciences, Chiba (Japan)

2002-03-01

133

Dose response of tracheal epithelial cells to ionizing radiation in air-liquid interface cultures  

International Nuclear Information System (INIS)

The dose-response relationships of tracheal epithelial cells to ionizing radiation was examined in air-liquid interface cultures, which were developed for the purpose of simulating in vivo conditions. The cultures investigated in this study were expected to be advantageous for the performance of irradiation experiments using short-range ? rays. The level of dose response of air-liquid interface cultures to ionizing radiation proved to be the same as that for in vivo conditions. This result indicates that air-liquid interface cultures will prove most useful, to facilitate future studies for the investigation of the biological effects induced in tracheal epithelial cells by ionizing radiation, especially by ?-rays. (orig.)

2002-01-01

134

Mathematical Models for Atmospheric Pollutants. Appendix D. Available Air Quality Models. Final Report.  

Science.gov (United States)

Models that are available for the analysis of airborne pollutants are summarized. In addition, recommendations are given concerning the use of particular models to aid in particular air quality decision making processes. The air quality models are charact...

R. L. Drake D. J. McNaughton C. Huang

1979-01-01

135

Dark Radiation Confronting LHC in Z' Models  

CERN Document Server

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 already existing constraints from searches for new neutral gauge bosons at LHC7.

Solaguren-Beascoa, A

2012-01-01

136

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.).

1990-01-01

137

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 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 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 (more) 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, Annand (more) ale, 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.

Silva, Cláudio R. da; Silva, Valdiney J. da; Alves Júnior, José; Carvalho, Hudson de P.

2012-01-01

138

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; Valdiney J. da Silva; José Alves Júnior; Hudson de P. Carvalho

2012-01-01

139

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

140

RRTM: A rapid radiative transfer model  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-04-01

 
 
 
 
141

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

Science.gov (United States)

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

Fry, M. M.; Schwarzkopf, M. D.; Adelman, Z.; Naik, V.; Collins, W. J.; West, J. J.

2013-05-01

142

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

Directory of Open Access Journals (Sweden)

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

M. M. Fry; M. D. Schwarzkopf; Z. Adelman; V. Naik; W. J. Collins; J. J. West

2013-01-01

143

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

Directory of Open Access Journals (Sweden)

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

M. M. Fry; M. D. Schwarzkopf; Z. Adelman; V. Naik; W. J. Collins; J. J. West

2012-01-01

144

DEVELOPMENT AND ANALYSIS OF AIR QUALITY MODELING SIMULATIONS FOR HAZARDOUS AIR POLLUTANTS  

Science.gov (United States)

The concentrations of five hazardous air pollutants were simulated using the Community Multi Scale Air Quality (CMAQ) modeling system. Annual simulations were performed over the continental United States for the entire year of 2001 to support human exposure estimates. Results a...

145

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

UK PubMed Central (United Kingdom)

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.

Breen MS; Schultz BD; Sohn MD; Long T; Langstaff J; Williams R; Isaacs K; Meng QY; Stallings C; Smith L

2013-05-01

146

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

147

Transport worker radiation exposures handling air shipments of radioactive materials  

International Nuclear Information System (INIS)

[en] 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

148

AIRFLY: Measurement of the Air Fluorescence Radiation Induced by Electrons  

International Nuclear Information System (INIS)

The AIRFLY (AIR FLuorescence Yield) experiment objective is the precise measurement of the fluorescence yield in atmospheric gases. AIRFLY takes data at the Beam Test Facility of the INFN Laboratori Nazionali di Frascati. A first test performed on the beam line has allowed to verify the feasibility of the physics program which includes an absolute measurement of the fluorescence yield with a precision better than 5%, the measurement of the spectrum and of the yield dependence on the electron energy, gas pressure, temperature and composition. Details of the experimental apparatus and preliminary results from the test are reported.

2006-01-01

149

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

150

The cost of simplifying air travel when modeling disease spread.  

UK PubMed Central (United Kingdom)

BACKGROUND: Air travel plays a key role in the spread of many pathogens. Modeling the long distance spread of infectious disease in these cases requires an air travel model. Highly detailed air transportation models can be over determined and computationally problematic. We compared the predictions of a simplified air transport model with those of a model of all routes and assessed the impact of differences on models of infectious disease. METHODOLOGY/PRINCIPAL FINDINGS: Using U.S. ticket data from 2007, we compared a simplified "pipe" model, in which individuals flow in and out of the air transport system based on the number of arrivals and departures from a given airport, to a fully saturated model where all routes are modeled individually. We also compared the pipe model to a "gravity" model where the probability of travel is scaled by physical distance; the gravity model did not differ significantly from the pipe model. The pipe model roughly approximated actual air travel, but tended to overestimate the number of trips between small airports and underestimate travel between major east and west coast airports. For most routes, the maximum number of false (or missed) introductions of disease is small (<1 per day) but for a few routes this rate is greatly underestimated by the pipe model. CONCLUSIONS/SIGNIFICANCE: If our interest is in large scale regional and national effects of disease, the simplified pipe model may be adequate. If we are interested in specific effects of interventions on particular air routes or the time for the disease to reach a particular location, a more complex point-to-point model will be more accurate. For many problems a hybrid model that independently models some frequently traveled routes may be the best choice. Regardless of the model used, the effect of simplifications and sensitivity to errors in parameter estimation should be analyzed.

Lessler J; Kaufman JH; Ford DA; Douglas JV

2009-01-01

151

Dynamic model of Earth's radiation belts  

Science.gov (United States)

The radiation belts are the region that energetic charged particles are trapped by Earth's magnetic field. It is well known that the energetic particle flux vary during geomagnetic distur-bances, and, the relativistic electrons in the outer radiation belt change with solar wind speed. Many researches have been studied about the flux variation of radiation belt, but the mecha-nism of the variation has not been understood in detail. We have developed a new dynamic model of energetic particles trapped in the based on the data from the MDS-1 spacecraft. This model reproduces the dynamic of radiation belt by running average using magnetic activity index(AP) and running average solar wind speed. This model covers the energy ranges of 0.4-2MeV for electrons, 0.9-210 MeV for protons, and 6-140 MeV for helium ions, and it is valid from low altitudes (approximately 500km) to geosynchronous orbit altitude. We discuss the advantage of the new model, and comparisons between MDS-1 data and our new model.

Matsumoto, Haruhisa; Koshiishi, Hideki; Goka, Tateo; Obara, Takahiro

152

Modeling and simulation of variable air volume air-conditioning system and its control strategy  

Energy Technology Data Exchange (ETDEWEB)

The use of variable-air-volume (VAV) systems in heating, ventilation, air conditioning systems (HVAC) applications in China has increased in recent years due to their energy efficiency. This study investigated the control and operation of a VAV system in a plaza in Shanghai, where 2 air handle units (AHUs), each with a variable speed fan, distribute tempered air into occupied spaces. Recirculated and outdoor air is mixed in a mixing box, cooled and then dehumidified in a cooling coil. A comprehensive modeling methodology was developed for the control strategy of the global VAV system in order to achieve optimal operation. Real VAV components were modeled in this study and combined with system level models using artificial neural network estimation based on 2 season's of experimental data obtained from the plaza. The model was capable of examining various optimal configurations. This study focused on the controllability of duct systems for a VAV system and presented a control strategy based on whole system operation. The model considered the AHU that connected the ductwork with all boxes, different zones and static pressure-correlation. The total air volume control strategy is not only expected to give good regulation of zone temperatures, but also minimize fan energy consumption. The overall VAV system is decomposed into a fast air flow system and a slow thermal system. The cascade control strategy successfully solved optimal operation challenges facing VAV systems. The simulation of the multizone VAV system revealed the best control parameters. 6 refs., 16 figs.

Zhao, Z.S.; Wu, Y.; Lu, J. [Shanghai Univ., Shanghai (China)

2007-08-09

153

Terahertz Radiation Source in Air Based on Bifilamentation of Femtosecond Laser Pulses  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new terahertz (THz) source in air based on the bifilamentation of femtosecond laser pulses is reported. This THz radiation is 1 order of magnitude more intense than the transition-Cherenkov THz emission from femtosecond laser filaments reported recently and shows different angular and polarization...

Liu, Yi; Houard, Aurélien; Akturk, Selcuk; Mysyrowicz, André; Tikhonchuk, Vladimir

154

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

155

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

156

Modeling of air flow through a narrow crack  

International Nuclear Information System (INIS)

[en] Radon transport in dwellings is governed to a significant extent by pressure differences and properties of transport pathways. A model of air flow through narrow cracks was created in order to facilitate prediction of air velocity and air flow. Theoretical calculations, based on numerical solution of a system of differential equations, were compared with measurements carried out on a window crack. (P.A.)

2004-07-02

157

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-12-15

158

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

159

FUZZY MODELLING OF LIQUID DESICCANT BASED AIR DEHUMIDIFICATION SYSTEM  

Directory of Open Access Journals (Sweden)

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

Harpreet Singh,; Jagdev Singh,; Simranpreet Singh Gill

2011-01-01

160

Modelling radiation fluxes in simple and complex environments--application of the RayMan model.  

Science.gov (United States)

The most important meteorological parameter affecting the human energy balance during sunny weather conditions is the mean radiant temperature T(mrt). It considers the uniform temperature of a surrounding surface giving off blackbody radiation, which results in the same energy gain of a human body given the prevailing radiation fluxes. This energy gain usually varies considerably in open space conditions. In this paper, the model 'RayMan', used for the calculation of short- and long-wave radiation fluxes on the human body, is presented. The model, which takes complex urban structures into account, is suitable for several applications in urban areas such as urban planning and street design. The final output of the model is, however, the calculated T(mrt), which is required in the human energy balance model, and thus also for the assessment of the urban bioclimate, with the use of thermal indices such as predicted mean vote (PMV), physiologically equivalent temperature (PET) and standard effective temperature (SET*). The model has been developed based on the German VDI-Guidelines 3789, Part II (environmental meteorology, interactions between atmosphere and surfaces; calculation of short- and long-wave radiation) and VDI-3787 (environmental meteorology, methods for the human-biometeorological evaluation of climate and air quality for urban and regional planning. Part I: climate). The validation of the results of the RayMan model agrees with similar results obtained from experimental studies. PMID:17093907

Matzarakis, Andreas; Rutz, Frank; Mayer, Helmut

2006-11-09

 
 
 
 
161

Modelling radiation fluxes in simple and complex environments--application of the RayMan model.  

UK PubMed Central (United Kingdom)

The most important meteorological parameter affecting the human energy balance during sunny weather conditions is the mean radiant temperature T(mrt). It considers the uniform temperature of a surrounding surface giving off blackbody radiation, which results in the same energy gain of a human body given the prevailing radiation fluxes. This energy gain usually varies considerably in open space conditions. In this paper, the model 'RayMan', used for the calculation of short- and long-wave radiation fluxes on the human body, is presented. The model, which takes complex urban structures into account, is suitable for several applications in urban areas such as urban planning and street design. The final output of the model is, however, the calculated T(mrt), which is required in the human energy balance model, and thus also for the assessment of the urban bioclimate, with the use of thermal indices such as predicted mean vote (PMV), physiologically equivalent temperature (PET) and standard effective temperature (SET*). The model has been developed based on the German VDI-Guidelines 3789, Part II (environmental meteorology, interactions between atmosphere and surfaces; calculation of short- and long-wave radiation) and VDI-3787 (environmental meteorology, methods for the human-biometeorological evaluation of climate and air quality for urban and regional planning. Part I: climate). The validation of the results of the RayMan model agrees with similar results obtained from experimental studies.

Matzarakis A; Rutz F; Mayer H

2007-03-01

162

Modelling radiation fluxes in simple and complex environments—application of the RayMan model  

Science.gov (United States)

The most important meteorological parameter affecting the human energy balance during sunny weather conditions is the mean radiant temperature Tmrt. It considers the uniform temperature of a surrounding surface giving off blackbody radiation, which results in the same energy gain of a human body given the prevailing radiation fluxes. This energy gain usually varies considerably in open space conditions. In this paper, the model ‘RayMan’, used for the calculation of short- and long-wave radiation fluxes on the human body, is presented. The model, which takes complex urban structures into account, is suitable for several applications in urban areas such as urban planning and street design. The final output of the model is, however, the calculated Tmrt, which is required in the human energy balance model, and thus also for the assessment of the urban bioclimate, with the use of thermal indices such as predicted mean vote (PMV), physiologically equivalent temperature (PET) and standard effective temperature (SET*). The model has been developed based on the German VDI-Guidelines 3789, Part II (environmental meteorology, interactions between atmosphere and surfaces; calculation of short- and long-wave radiation) and VDI-3787 (environmental meteorology, methods for the human-biometeorological evaluation of climate and air quality for urban and regional planning. Part I: climate). The validation of the results of the RayMan model agrees with similar results obtained from experimental studies.

Matzarakis, Andreas; Rutz, Frank; Mayer, Helmut

2007-03-01

163

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

164

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

165

The Regional Municipality of Durham : corporate model for clean air  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this document is to encourage municipalities around Toronto, Ontario to develop and enact smog plans for their region. It seeks to establish a framework for the Durham region to implement policies, procedures, and practices aimed at improving local air quality, improving the health of the community and protecting the environment. The document provides an overview of smog in Ontario and discusses the health effects of air pollution. It discusses the air quality index and smog watches and smog advisories including historical data on Ontario smog days. It then presents a corporate model for clean air for the Durham Region. tabs., figs., 2 apps.

NONE

2004-11-01

166

Modeling the exit velocity of a compressed air cannon  

Science.gov (United States)

The use of compressed air cannons in an undergraduate laboratory provides a way to illustrate the connection between diverse physics concepts, such as conservation of momentum, the work-kinetic energy theorem, gas expansion, air drag, and elementary Newtonian mechanics. However, it is not clear whether the expansion of the gas in the cannon is an adiabatic or an isothermal process. We built an air cannon that utilizes a diaphragm valve to release the pressurized gas and found that neither process accurately predicts the exit velocity of our projectile. We discuss a model based on the flow of air through the valve, which is in much better agreement with our data.

Rohrbach, Z. J.; Buresh, T. R.; Madsen, M. J.

2012-01-01

167

A modeling perspective on cloud radiative forcing  

International Nuclear Information System (INIS)

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

1993-01-01

168

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

UK PubMed Central (United Kingdom)

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.

Fujimoto K

1998-09-01

169

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

170

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

2007-01-01

171

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)

1995-01-01

172

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

173

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.

2009-01-01

174

Dark Radiation in LARGE Volume Models  

CERN Multimedia

We consider reheating driven by volume modulus decays in the LARGE Volume Scenario. Such reheating always generates non-zero dark radiation through the decays to the axion partner, while the only competitive visible sector decays are Higgs pairs via the Giudice-Masiero term. In the framework of sequestered models where the cosmological moduli problem is absent, the simplest model with a shift-symmetric Higgs sector generates 1.56 < N_{eff} - N_{eff,SM} < 1.74. For more general cases, the known experimental bounds on N_{eff} strongly constrain the parameters and matter content of the models.

Cicoli, Michele; Quevedo, Fernando

2012-01-01

175

Preparation and characterization of Bragg fibers with air cores for transfer of laser radiation  

Science.gov (United States)

This paper presents results of preparation and characterization of Bragg fibers with silica and air cores designed for delivery of laser radiation at 1060 nm. The fibers consist of cores with a refractive index equal to that of air or silica which is surrounded by three pairs of Bragg layers. Each pair is composed of one layer with a high and one layer with a low refractive index and is characterized by a refractive-index contrast up to 0.03. Three structures of Bragg fibers are presented in the paper, namely the structure with a silica core of 26 ?m in diameter, structure with an air core of 5 ?m in diameter and that with an air core of a diameter of 72 ?m. Preforms of the Bragg fibers in the form of a rod or tube have been prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers have been drawn from the preforms under controlled temperatures in order to obtain fibers with air or solid cores. Results of characterization of prepared fibers with optical microscopy and by measuring their refractive-index profiles, losses and angular distributions of the output optical power are presented. The characterization of fibers for delivery radiation of a Nd:YAG laser with nanosecond pulses at 1060 nm, namely the transmission, attenuation coefficient, spatial profiles of transmitted beams, and bending losses are also presented. Fiber damage thresholds in a range 25-30 GW/cm2 have been determined.

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

2013-05-01

176

Olfactory and chemical characterization of indoor air. Towards a psychophysical model for air quality  

Energy Technology Data Exchange (ETDEWEB)

The relationship between the odor strength of total air samples and the odor strengths of the constituents was investigated in three field experiments in an office building and a new preschool. The odor strength was scaled by magnitude estimation according to a master scale principle which results in comparable values for the total and the constituent odors. Between 60 and 120 chemical components were detected by GC/FID in the indoor air samples (N = 66). Most (81%) of the detected components in an air sample were odorous, even though most of them were of low concentrations. By a method of pattern analysis, chemical as well as odor patterns of indoor air were found to be characteristic of different buildings. From the odor patterns (POG), the ''odor print'' of the outdoor air associated with the buildings was also recognized in the indoor air. Thus, the ''odor print'' of an air sample is different from its ''chemical print.'' A model was found that predicts the overall odor strength of an air sample from the number of FID-detected components most frequently reported to have a strong odor.

Berglund, B. (Univ. of Stockholm, Sweden); Berglund, U.; Lindvall, T.; Nicander-Bredberg, H.

1982-01-01

177

Clouds in a one dimensional radiation model  

Energy Technology Data Exchange (ETDEWEB)

The importance of clouds for the radiation budget of the earth is well known but less understood. This study compares several broadband parameterizations for the radiative properties of clouds from the works of different authors. Water and ice clouds are treated separately. All parameterizations are based on the effective radius (r{sub e}) as a measure for the microphysical composition of the clouds. The clouds are embedded in a one dimensional radiation scheme of the type suitable for GCMs and NWP models. A water cloud from JASIN and two ice clouds from ICE`89 are chosen as test cases. The radiative fluxes, both SW and LW, from any of the tested parameterizations are close to the observations. The LW fluxes in ice clouds are the only situations where ECHAM is clearly closer to the observations than ECMWF. The SW cloud absorption from this study is slightly higher for both water and ice clouds compared to other models or observations. Only qualitative statements are possible concerning the LW cloud absorption because additional, non-observed but probably present clouds below or above the test clouds may easily affect the absorption. 29 refs, 8 refs, 10 tabs

Wyser, K.

1996-05-01

178

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...

179

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

180

Biologically based multistage modeling of radiation effects  

Energy Technology Data Exchange (ETDEWEB)

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

William Hazelton; Suresh Moolgavkar; E. Georg Luebeck

2005-08-30

 
 
 
 
181

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-04-01

182

Modelling and control of an air-to-air heat recovery system  

Energy Technology Data Exchange (ETDEWEB)

Analytical modelling, controller design and simulation of an air-to-air runaround coil heat recovery system are studied. Simulation results showing the transient response characteristics of the open-loop and closed-loop system are given. Results show that the designed controllers are able to hold the preheat temperature and the storage tank temperature at their respective setpoints irrespective of changes in outdoor and exhaust (source heat) temperatures. (author)

Zaheer-Uddin, M.; Wang, J.C.Y. (Concordia Univ., Sir George Williams Campus, Montreal, PQ (Canada). Centre for Building Studies)

1994-03-01

183

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

Energy Technology Data Exchange (ETDEWEB)

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 {approximately}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 {gamma}-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.

Yukhimuk, V.; Roussel-Dupre, R.; Symbalisty, E.; Taranenko, Y.

1997-04-01

184

Modeling of sound radiation by a beam ????????????? ????????? ???? ?????? ??????????? ?????????????? ???? ??????  

Directory of Open Access Journals (Sweden)

Full Text Available  An analytical formulation and numerical analysis are presented for the vibration and following noise radiation of a simply supported beam. The analytical solution was found in a form that is appropriate to describe the control of the beam vibration using active structures. The modeling approach can be used for forming of feedback control of the system of vibration loads by means of distribution of the actuators along the beam length.

?.?. Zaporozhets; V.?. Tokarev; Werner Hufenba?h; Shtefen Marburg; Olaf Taeger; Nils Modler; Martin Dannemann

2005-01-01

185

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

186

Control of asthma triggers in indoor air with air cleaners: a modeling analysis.  

UK PubMed Central (United Kingdom)

BACKGROUND: Reducing exposure to environmental agents indoors shown to increase asthma symptoms or lead to asthma exacerbations is an important component of a strategy to manage asthma for individuals. Numerous investigations have demonstrated that portable air cleaning devices can reduce concentrations of asthma triggers in indoor air; however, their benefits for breathing problems have not always been reproducible. The potential exposure benefits of whole house high efficiency in-duct air cleaners for sensitive subpopulations have yet to be evaluated. METHODS: We used an indoor air quality modeling system (CONTAM) developed by NIST to examine peak and time-integrated concentrations of common asthma triggers present in indoor air over a year as a function of natural ventilation, portable air cleaners, and forced air ventilation equipped with conventional and high efficiency filtration systems. Emission rates for asthma triggers were based on experimental studies published in the scientific literature. RESULTS: Forced air systems with high efficiency filtration were found to provide the best control of asthma triggers: 30-55% lower cat allergen levels, 90-99% lower risk of respiratory infection through the inhalation route of exposure, 90-98% lower environmental tobacco smoke (ETS) levels, and 50-75% lower fungal spore levels than the other ventilation/filtration systems considered. These results indicate that the use of high efficiency in-duct air cleaners provide an effective means of controlling allergen levels not only in a single room, like a portable air cleaner, but the whole house. CONCLUSION: These findings are useful for evaluating potential benefits of high efficiency in-duct filtration systems for controlling exposure to asthma triggers indoors and for the design of trials of environmental interventions intended to evaluate their utility in practice.

Myatt TA; Minegishi T; Allen JG; Macintosh DL

2008-01-01

187

Control of asthma triggers in indoor air with air cleaners: a modeling analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Reducing exposure to environmental agents indoors shown to increase asthma symptoms or lead to asthma exacerbations is an important component of a strategy to manage asthma for individuals. Numerous investigations have demonstrated that portable air cleaning devices can reduce concentrations of asthma triggers in indoor air; however, their benefits for breathing problems have not always been reproducible. The potential exposure benefits of whole house high efficiency in-duct air cleaners for sensitive subpopulations have yet to be evaluated. Methods We used an indoor air quality modeling system (CONTAM) developed by NIST to examine peak and time-integrated concentrations of common asthma triggers present in indoor air over a year as a function of natural ventilation, portable air cleaners, and forced air ventilation equipped with conventional and high efficiency filtration systems. Emission rates for asthma triggers were based on experimental studies published in the scientific literature. Results Forced air systems with high efficiency filtration were found to provide the best control of asthma triggers: 30–55% lower cat allergen levels, 90–99% lower risk of respiratory infection through the inhalation route of exposure, 90–98% lower environmental tobacco smoke (ETS) levels, and 50–75% lower fungal spore levels than the other ventilation/filtration systems considered. These results indicate that the use of high efficiency in-duct air cleaners provide an effective means of controlling allergen levels not only in a single room, like a portable air cleaner, but the whole house. Conclusion These findings are useful for evaluating potential benefits of high efficiency in-duct filtration systems for controlling exposure to asthma triggers indoors and for the design of trials of environmental interventions intended to evaluate their utility in practice.

Myatt Theodore A; Minegishi Taeko; Allen Joseph G; MacIntosh David L

2008-01-01

188

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

UK PubMed Central (United Kingdom)

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

Pratt GC; Dymond M; Ellickson K; Thé J

2012-01-01

189

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

Science.gov (United States)

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

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

2011-06-08

190

Multicomponent gas mixture air bearing modeling via lattice Boltzmann method  

Science.gov (United States)

As the demand for ultrahigh recording density increases, development of an integrated head disk interface (HDI) modeling tool, which considers the air bearing and lubricant film morphology simultaneously is of paramount importance. To overcome the shortcomings of the existing models based on the modified Reynolds equation (MRE), the lattice Boltzmann method (LBM) is a natural choice in modeling high Knudsen number (Kn) flows owing to its advantages over conventional methods. The transient and parallel nature makes this LBM an attractive tool for the next generation air bearing design. Although LBM has been successfully applied to single component systems, a multicomponent system analysis has been thwarted because of the complexity in coupling the terms for each component. Previous studies have shown good results in modeling immiscible component mixtures by use of an interparticle potential. In this paper, we extend our LBM model to predict the flow rate of high Kn pressure-driven flows in multicomponent gas mixture air bearings, such as the air-helium system. For accurate modeling of slip conditions near the wall, we adopt our LBM scheme with spatially dependent relaxation times for air bearings in HDIs. To verify the accuracy of our code, we tested our scheme via simple two-dimensional benchmark flows. In the pressure-driven flow of an air-helium mixture, we found that the simple linear combination of pure helium and pure air flow rates, based on helium and air mole fraction, gives considerable error when compared to our LBM calculation. Hybridization with the existing MRE database can be adopted with the procedure reported here to develop the state-of-the-art slider design software.

Tae Kim, Woo; Kim, Dehee; Hari Vemuri, Sesha; Kang, Soo-Choon; Seung Chung, Pil; Jhon, Myung S.

2011-04-01

191

Modeling forest responses to air pollution: Discussion summary  

Energy Technology Data Exchange (ETDEWEB)

The discussion session outlined three required elements of any approach to modeling forest responses to air pollution: deposition models, models of primary plant responses to air pollutants, and models to translate those responses into altered patterns of growth. The open discussion included a range of topics covering aspects of each of these three areas. The following summary was derived from notes taken during the discussions and a tape recording of the actual session. Every attempt has been made to attribute questions and comments to the appropriate individuals.

Hanson, P.J.

1988-01-01

192

Neuro-models for discharge air temperature system  

Energy Technology Data Exchange (ETDEWEB)

Nonlinear neuro-models for a discharge air temperature (DAT) system are developed. Experimental data gathered in a heating ventilating and air conditioning (HVAC) test facility is used to develop multi-input multi-output (MIMO) and single-input single-output (SISO) neuro-models. Several different network architectures were explored to build the models. Results show that a three layer second order neural network structure is necessary to achieve good accuracy of the predictions. Results from the developed models are compared, and some observations on sensitivity and standard deviation errors are presented. (author)

Zaheer-uddin, M.; Tudoroiu, N. [Concordia University, Montreal (Canada). Centre for Building Studies

2004-04-01

193

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

International Nuclear Information System (INIS)

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

1988-01-01

194

Review of air quality modeling techniques. Volume 8  

International Nuclear Information System (INIS)

Air transport and diffusion models which are applicable to the assessment of the environmental effects of nuclear, geothermal, and fossil-fuel electric generation are reviewed. The general classification of models and model inputs are discussed. A detailed examination of the statistical, Gaussian plume, Gaussian puff, one-box and species-conservation-of-mass models is given. Representative models are discussed with attention given to the assumptions, input data requirement, advantages, disadvantages and applicability of each

1977-01-01

195

Photon radiation and the air kerma rate constants of 152Eu and 154Eu radionuclides  

International Nuclear Information System (INIS)

[en] It is often required to estimate the kerma rate at a distance from the radionuclides sources emitted photon radiation such as, for instance, 152Eu and 154Eu which represents frequently used sources in many fields of science, technology and medicine. The factor relating activity and air kerma is the air kerma rate constant - ??. Analysis of accessible data on this quantity for mentioned radionuclides led us to the conclusion that discrepancies in reported calculated values exist because the radionuclides decay scheme and other nuclear spectroscopy data pertinent to these calculations were not well known. That is the reason we calculated these quantities on the basis of our methodology, nuclear spectroscopy data given by many authors and the latest data for the mass-energy transfer coefficients for air. In this way the air kerma rate constants are calculated to be 41,1 ± 0,6 aGy m2 s-1 Bq-1 for 152Eu and 44,1 ± 0,2 aGy m2 s-1 Bq-1 for 154Eu. Calculation was made for the unfiltered point source including emitted photon radiation with energies greater than 20 keV and yield per decay event higher than 0,05%. (author)

2000-01-01

196

Disk modelling by radiation-magnetohydrodynamic simulations  

Directory of Open Access Journals (Sweden)

Full Text Available Historically, various accretion models have been discussed under radially one-zone approximations. In such one-zone models, however, dynamical aspects of the accretion flow, such as internal circulation and outflows, have been totally neglected. Further, the disk viscosity is usually described by the phenomenological ?-viscosity model. We, here, elucidate the theory of accretion flows and outflows based on our global, two-dimensional radiation-magnetohydrodynamic simulations, not relying on the ? model. We have succeeded in producing three distinct states of accretion flow by controling only one parameter, a density normalization. Of particular importance is the presence of outflows in all three states. Several noteworthy features of the supercritical (or super-Eddington) accretion flows are found; that is, relativistic, collimated outflows (jets), and low-velocity, uncollimated outflows with clumpy structure. Observational implications are briefly discussed.

Mineshige S.; Ohsuga K.; Takeuchi S.

2012-01-01

197

Air pollution modeling and its application VI  

Energy Technology Data Exchange (ETDEWEB)

54 papers presented at the conference are included under the following topic headings: dry deposition: theory and experiment; wet scavenging processes and physico/chemical processes in clouds; meteorological parameterisation in dispersion modeling; model verification and policy implications; the PHOXA project; the Chernobyl accident; and new developments in dispersion modeling and theory.

Dop, H. van (ed.)

1988-01-01

198

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; P. Forster

2007-01-01

199

Solar radiation practical modeling for renewable energy applications  

CERN Multimedia

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

Myers, Daryl Ronald

2013-01-01

200

Radiation dose estimates due to air particulate emissions from selected phosphate industry operations  

International Nuclear Information System (INIS)

[en] The EPA Office of Radiation Programs has conducted a series of studies to determine the radiological impact of the phosphate mining and milling industry. This report describes the efforts to estimate the radiation doses due to airborne emissions of particulates from selected phosphate milling operations in Florida. Two wet process phosphoric acid plants and one ore drying facility were selected for this study. The 1976 Annual Operations/Emissions Report, submitted by each facility to the Florida Department of Environmental Regulation, and a field survey trip by EPA personnel to each facility were used to develop data for dose calculations. The field survey trip included sampling for stack emissions and ambient air samples collected in the general vicinity of each plant. Population and individual radiation dose estimates are made based on these sources of data

1978-01-01

 
 
 
 
201

Mathematical Modeling of Hot Air Drying of Spinach Leaves in Universal Hot Air Oven  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study was to develop a model for drying characteristic curve of Spinach in Universal Hot Air Oven .Drying experiment were conducted using a constant air velocity2.2m/s and three drying air temperature of 55, 65, and75 oC with two pretreatment conditions and load densities that are given respectively condition (Blanched and Unblanched) load density (3kg/m2, 3.5 kg/m2).The drying rate increased with increased in temperature and decrease with increase in time. Pretreatment and load densities had an insignificant role on drying rate. The experimental drying data of spinach applied to four moisture ratio models, namely, page l, modified page, generalized exponential, and two term models. Nonlinear regression analysis performed to relate the parameters of the model with the drying conditions. The performance of these models evaluated by comparing the coefficient of determination, R2, and reduced chi-square, ?2, between the observed and predicted moisture ratio. Among all these model page model was found to be best describe the drying behavior of spinach leaves .the standard error of estimation was least(0.004-0.031) as well as coefficient of determination (R2)was highest (0.991-1) in page model as compared to other models.

A.K.Upadhyaya , Bhupendra Gupta , Sanjeev Garg , Mohan Singh , Mukesh Pandey

2012-01-01

202

Theoretical method for calculating solar radiation in terms of air temperature or sunshine duration using fourier series  

International Nuclear Information System (INIS)

Because of the periodicity of variations in solar radiation 'R', air temperature 'T' and sunshine duration 'S', their values are expanded in fourier series. Fourier coefficients are determined by using measured meteorological data of the selected egyptian weather stations. These coefficients are used to calculate solar radiation is presented in tables and graphs. The comparison shows a good agreement between the observed and estimated solar radiation. The method is applied to calculate the solar radiation for another stations where solar radiation measurements are unavailable, using records of air temperature or sunshine duration at these stations and solar radiation measured at the nearest meteorological stations. The estimated global solar radiation at any area is used to know the atmospheric stability, which is used to calculate the dispersion of pollutants in this area.

203

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

204

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; F. G. Wienhold; C. R. Hoyle; F. Immler; T. Peter

2011-01-01

205

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

Science.gov (United States)

...and D.J. Thompson, 1990. Developments in Modeling Air Pollution for Regulatory Uses. In Proceedings of the 18th NATO/CCMS International Technical Meeting on Air Pollution Modeling and its Application, Vancouver, Canada. Also In Air...

2010-07-01

206

Modeling of an electrically rechargeable alkaline zinc-air battery  

Energy Technology Data Exchange (ETDEWEB)

A numerical model has been developed to simulate the charging and discharge behaviour of an electrically rechargeable alkaline zinc-air battery. Further a galvanostatic experiment including three charge/discharge cycles has been performed. The cell voltages, the Zn electrode potentials versus a Zn reference, and the O{sub 2} electrode potentials versus a Zn reference calculated with the model are in fairly good agreement with the corresponding experimental data. The model is expected to be useful for zinc-air battery design and for analysis of experimental data. (author)

Deiss, E.; Holzer, F.; Haas, O.

2003-03-01

207

Monte Carlo modeling of the scatter radiation doses in IR  

Science.gov (United States)

Purpose: To use Monte Carlo techniques to compute the scatter radiation dose distribution patterns around patients undergoing Interventional Radiological (IR) examinations. Method: MCNP was used to model the scatter radiation air kerma (AK) per unit kerma area product (KAP) distribution around a 24 cm diameter water cylinder irradiated with monoenergetic x-rays. Normalized scatter fractions (SF) were generated defined as the air kerma at a point of interest that has been normalized by the Kerma Area Product incident on the phantom (i.e., AK/KAP). Three regions surrounding the water cylinder were investigated consisting of the area below the water cylinder (i.e., backscatter), above the water cylinder (i.e., forward scatter) and to the sides of the water cylinder (i.e., side scatter). Results: Immediately above and below the water cylinder and in the side scatter region, values of normalized SF decreased with the inverse square of the distance. For z-planes further away, the decrease was exponential. Values of normalized SF around the phantom were generally less than 10-4. Changes in normalized SF with x-ray energy were less than 20% and generally decreased with increasing x-ray energy. At a given distance from region where the x-ray beam enters the phantom, the normalized SF was higher in the backscatter regions, and smaller in the forward scatter regions. The ratio of forward to back scatter normalized SF was lowest at 60 keV and highest at 120 keV. Conclusion: Computed SF values quantify the normalized fractional radiation intensities at the operator location relative to the radiation intensities incident on the patient, where the normalization refers to the beam area that is incident on the patient. SF values can be used to estimate the radiation dose received by personnel within the procedure room, and which depend on the imaging geometry, patient size and location within the room. Monte Carlo techniques have the potential for simulating normalized SF values for any arrangement of imaging geometry, patient size and personnel location and are therefore an important tool for minimizing operator doses in IR.

Mah, Eugene; He, Wenjun; Huda, Walter; Yao, Hai; Selby, Bayne

2011-03-01

208

A simple atrium air model for atria  

Energy Technology Data Exchange (ETDEWEB)

Stratification occurs due to the strong solar influence which leads to high surface temperature and thereby to stronger surface convection. The high overall indoor temperature in atria will also lead to stronger natural ventilation compared to common rooms. Models for the two thermal powers are presented in this paper. The layered room model involving the thermal models for surface convection and natural ventilation is implemented in a computer program. The results of the computations have been compared with measurements and the results found promising. Therefor further development of the model is anticipated. (orig.)

Heller, A. [Dept. of Buildings and Energy, Technical Univ. of Denmark, Lyngby (Denmark)

1996-12-31

209

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

210

Modeling greenhouse air humidity by means of artificial neural network and principal component analysis  

UK PubMed Central (United Kingdom)

A back propagation neural network (BPNN) based on principal component analysis (PCA) was proposed for modeling the internal greenhouse humidity in winter of North China. The environment factors influencing the inside humidity include outside air temperature and humidity, wind speed, solar radiation, inside air temperature, open angle of top vent and side vent, and open ration of sunshade curtain, which were all collected as data samples. Through PCA of these data samples, 4 main factors were extracted, and the relationship between the main factors and the original data was discussed. Taking the principal component values as the input of BPNN, the model showed a good performance. A comparison was made between the performances of the BPNN based on PCA and the stepwise regression method with 20 data samples which had not been used to establish the NN model, and the prediction of stepwise regression method was less accurate than the BPNN based on PCA.

He Fen; Ma Chengwei

2010-04-01

211

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...

212

Numerical modelling of negative discharges in air with experimental validation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

213

FUNDAMENTAL MASS TRANSFER MODELS FOR INDOOR AIR POLLUTION SOURCES  

Science.gov (United States)

The paper discusses a simple, fundamental mass transfer model, based on Fick's Law of Diffusion, for indoor air pollution wet sorbent-based sources. (Note: Models are needed to predict emissions from indoor sources. hile empirical approaches based on dynamic chamber data are usef...

214

A 331 WIMPy Dark Radiation Model  

CERN Document Server

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

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

2013-01-01

215

Solar radiation modelling in the urban context  

Energy Technology Data Exchange (ETDEWEB)

This paper describes alternative methods for predicting surface irradiance in the urban context. In this the focus is on means of accounting for the effects of nearby obstructions on reducing direct sky radiation and on contributing reflected radiation. The first two methods involve abstracting the urban skyline into an effective canyon using isotropic and anisotropic tilted surface irradiance models. The third predicts the irradiance contribution from two hemispheres which are discretised into patches - given the radiance of the sky and dominant obstructions (if these exist) and associated view factors - so that we have a new simplified radiosity algorithm (SRA). Results from the three methods (isotropic canyon (IC), anisotropic canyon (AC) and simplified radiosity algorithm (SRA)) are compared with a 'truth model' under the following circumstances: (i) unobstructed sky, (ii) sky obstructed by black surfaces, (iii) sky obstructed by grey diffusely reflecting surfaces. Results show conclusively that the SRA offers superior accuracy at comparable speed to the canyon models. The SRA also compares well with a ray tracing program, it can handle urban scenes of arbitrary geometric complexity and is readily amenable for inclusion into standard computer programs that require surface irradiance as an input. (author)

Robinson, D.; Stone, A. [BDSP Partnership Limited, London (United Kingdom)

2004-09-01

216

Modeling the radiation response of Chlamydomonas reinhardi  

International Nuclear Information System (INIS)

To pursue our goal of establishing quantitative relations between initial physical events produced by ionizing radiation and the subsequent biological effects in cells, we have been developing and testing theoretical models for two kinds of cells, the mammalian Chinese hamster ovary (CHO) cell and the green alga, Chlamydomonas reinhardi. The hamster cell studies are beginning to produce results and will be discussed below. The C. reinhardt studies have been in progress for some time and illustrate the normal scientific cycle of framing, testing, and revising hypotheses

1983-01-01

217

Low dose radiation effects: a holistic model  

International Nuclear Information System (INIS)

Mathematical model of low dose irradiation effects based on molecular and physiological parameters of cell response was presented. Data mainly on three aspects of the problem were used: - fact of presence of nonmonotonous discontinuous dose-effect dependences with respect to low doses was taken into consideration. Selection of such curves was based on empirical approach and needed analytical assessment; - effects of adaptive response of animal cells and induced repair systems were taken into consideration; - occurrence of optimal bioeconomical process was supposed to be a basis of effect of various background radiation on the organism. 29 refs.; 6 figs

1990-01-01

218

Solar Radiation Pressure Modeling Issues for High Altitude Satellite.  

Science.gov (United States)

Current satellite orbit propagation techniques employ a solar radiation pressure model that makes simplifying assumptions concerning the satellite and its orbital geometry. Solar radiation pressure, a non- gravitational perturbation, significantly affects...

D. G. Cook

2001-01-01

219

Mathematical models for atmospheric pollutants. Appendix D. Available air quality models. Final report  

International Nuclear Information System (INIS)

Models that are available for the analysis of airborne pollutants are summarized. In addition, recommendations are given concerning the use of particular models to aid in particular air quality decision making processes. The air quality models are characterized in terms of time and space scales, steady state or time dependent processes, reference frames, reaction mechanisms, treatment of turbulence and topography, and model uncertainty. Using these characteristics, the models are classified in the following manner: simple deterministic models, such as air pollution indices, simple area source models and rollback models; statistical models, such as averaging time models, time series analysis and multivariate analysis; local plume and puff models; box and multibox models; finite difference or grid models; particle models; physical models, such as wind tunnels and liquid flumes; regional models; and global models

1979-01-01

220

Air cooling of a vented enclosure by combined conduction, natural convection and radiation  

Energy Technology Data Exchange (ETDEWEB)

A three-dimensional investigation of combined conduction, natural convection and radiation in vented enclosures is carried out. A discrete flush type heat source mounted on a vertical substrate is used to simulate an electronic component. A uniform volumetric generation rate is assumed within the heat source. Combined natural convection in the air, conduction in the heat source, the substrate and the enclosure walls, and surface radiation are solved for Rayleigh numbers at 2.6 {times} 10{sup 6} and 2.0 {times} 10{sup 7}. Radiation is incorporated based on the radiosity/irradiation approach. The resulting flow and temperature patterns are discussed, focusing on radiation and three-dimensional effects. The relative contributions of natural convection and radiation are investigated for different emissivities of internal surface of the substrate. Heat transfer rates from the substrate and other internal walls are presented to illustrate conjugate heat transfer due to combined modes. The numerical solutions are found in reasonably good agreement with the data.

Yu, E.; Joshi, Y.K. [Univ. of Maryland, College Park, MD (United States)

1996-12-31

 
 
 
 
221

A Hybrid Neural Network Prediction Model of Air Ticket Sales  

Directory of Open Access Journals (Sweden)

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

Han-Chen Huang

2013-01-01

222

Modeling of hybrid combustion turbine inlet air cooling systems  

Energy Technology Data Exchange (ETDEWEB)

Thermal energy storage has been proposed as a viable cost-effective capacity enhancement method when applied to cool inlet air for combustion turbines. Emphasis has been placed on the use of ice-only thermal energy storage systems for inlet air cooling. In this paper, the efficacy and cost-effectiveness of ice storage compared with chilled water storage, hybrid (ice/chilled water) storage, and evaporative cooling are explored. Detailed mechanistic models of a combustion gas turbine, ice harvester, chiller, and associated storage components are developed and calibrated using manufacturer`s data. The performance of different systems with a series of four power plant load profiles is determined by simulation. Appropriate storage systems are sized to provide inlet air cooling for a combustion turbine dispatched to meet the load profiles. Capacity enhancement costs are determined for chilled water storage, ice storage, and the hybrid storage systems providing inlet air cooling for the combustion turbine.

Cross, J.K.; Beckman, W.A.; Mitchell, J.W.; Reindl, D.T.; Knebel, D.E. [Univ. of Wisconsin, Madison, WI (United States)

1995-12-31

223

Mathematical modeling of compression processes in air-driven boosters  

International Nuclear Information System (INIS)

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

2007-01-01

224

Extensive Air Showers Model Dependence And The Longitudinal Profile  

CERN Multimedia

The physics of atmospheric cascades induced by ultrahigh energy cosmic rays above the GZK cutoff is investigated. A flexible air shower generator is developed for the exploration of air shower properties under various assumptions about the underlying hadronic physics. Included is an efficient algorithm for the simulation of electromagnetic cascades which emphasizes consistency with the standard Greisen formula for photons. The uncertainties in hadronic interaction physics relevant to air shower properties are bracketed with conservative models which characterize limiting scenarios. The effects of scaling violations in hadron-nucleon and hadron- nucleus iteractions are addressed. Emphasis is on the fragmentation region which is of most relevance to air shower development. The physics uncertainties imply an uncertainty in the average depth at maximum for proton induced cascades at the highest energies which is comparable to the separation between protons and iron. Consequently, it will be difficult to extract i...

Mikulski, P T

2000-01-01

225

AQA - Air Quality model for Austria - Evaluation and Developments  

Science.gov (United States)

The regional weather forecast model ALADIN of the Central Institute for Meteorology and Geodynamics (ZAMG) is used in combination with the chemical transport model CAMx (www.camx.com) to conduct forecasts of gaseous and particulate air pollution over Europe. The forecasts which are done in cooperation with the University of Natural Resources and Applied Life Sciences in Vienna (BOKU) are supported by the regional governments since 2005 with the main interest on the prediction of tropospheric ozone. The daily ozone forecasts are evaluated for the summer 2008 with the observations of about 150 air quality stations in Austria. In 2008 the emission-model SMOKE was integrated into the modelling system to calculate the biogenic emissions. The anthropogenic emissions are based on the newest EMEP data set as well as on regional inventories for the core domain. The performance of SMOKE is shown for a summer period in 2007. In the frame of the COST-action 728 „Enhancing mesoscale meteorological modelling capabilities for air pollution and dispersion applications", multi-model ensembles are used to conduct an international model evaluation. The model calculations of meteorological- and concentration fields are compared to measurements on the ensemble platform at the Joint Research Centre (JRC) in Ispra. The results for 2 episodes in 2006 show the performance of the different models as well as of the model ensemble.

Hirtl, M.; Krüger, B. C.; Baumann-Stanzer, K.; Skomorowski, P.

2009-04-01

226

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.

Suwari Suwari; Etty Riani; Bambang Pramudya; Ita Djuwita

2011-01-01

227

CFD Modeling For Urban Air Quality Studies  

Energy Technology Data Exchange (ETDEWEB)

The computational fluid dynamics (CFD) approach has been increasingly applied to many atmospheric applications, including flow over buildings and complex terrain, and dispersion of hazardous releases. However there has been much less activity on the coupling of CFD with atmospheric chemistry. Most of the atmospheric chemistry applications have been focused on the modeling of chemistry on larger spatial scales, such as global or urban airshed scale. However, the increased attentions to terrorism threats have stimulated the need of much more detailed simulations involving chemical releases within urban areas. This motivated us to develop a new CFD/coupled-chemistry capability as part of our modeling effort.

Lee, R L; Lucas, L J; Humphreys, T D; Chan, S T

2003-10-27

228

Modeling of the Lunar Radiation Environment  

Energy Technology Data Exchange (ETDEWEB)

In view of manned missions targeted to the Moon, for which radiation exposure is one of the greatest challenges to be tackled, it is of fundamental importance to have available a tool, which allows the determination of the particle flux and spectra at any time and at any point of the lunar surface. With this goal in mind, a new model of the Moon's radiation environment due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) has been developed. Primary particles reach the lunar surface, and are transported all throughout the subsurface layers, with backscattering patterns taken into account. The surface itself has been modeled as regolith and bedrock, with composition taken from the results of the instruments flown on the Apollo missions. Subsurface environments like lava tubes have been considered in the analysis. Particle transport has been performed with both deterministic and Monte Carlo codes with an adaptation for planetary surface geometry. Results are given in terms of fluxes, doses and LET, for most kinds of particles for various kinds of soil and rock chemical compositions.

De Angelis, G. [Istituto Superiore di Sanita, Rome, I-00161 (Italy); Badavi, F.F. [Christopher Newport University, Newport News, VA 23606 (United States); Clem, J.M. [Bartol Research Institute, University of Delaware, Newark, DE 23508 (United States); Blattnig, S.R.; Clowdsley, M.S. [NASA Langley Research Center, Hampton, VA 23681 (United States); Nealy, J.E. [Old Dominion University, Norfolk, VA 23508 (United States); Tripathi, R.K.; Wilson, J.W. [NASA Langley Research Center, Hampton, VA 23681 (United States)

2007-04-15

229

An Analytical Air Pollution Model with Time Dependent Eddy Diffusivity  

Directory of Open Access Journals (Sweden)

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

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

2013-01-01

230

Modeling of extensive air showers with CORSIKA and CONEX  

International Nuclear Information System (INIS)

Entering the Earth's atmosphere, high-energy cosmic rays produce cascades of many secondary particles. Detailed modeling of these extensive air showers is needed to obtain information on the primary particles from the observed particle showers. In this article, the two in Karlsruhe developed air shower simulation packages CORSIKA and CONEX are introduced and their predictions for important shower observables are discussed. Emphasis is put on the role of hadronic interaction models, which have to be extrapolated to energies far beyond those available at man-made accelerators. (orig.)

2007-01-01

231

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

232

Realistic model for radiation-matter interaction  

CERN Multimedia

This paper presents a realistic model that describes radiation-matter interactions. This is achieved by a generalization of first quantization, where the Maxwell equations are interpreted as the electromagnetic component of the Schrodinger equation. This picture is complemented by the consideration of electrons and photons as real particles in three-dimensional space, following guiding conditions derived from the particle-wave-functions to which they are associated. The guiding condition for the electron is taken from Bohmian mechanics, while the photon velocity is defined as the ratio between the Poynting vector and the electromagnetic energy density. The case of many particles is considered, taking into account their statistical properties. The formalism is applied to a two level system, providing an intuitive description for spontaneous emission, Lamb shift, scattering, absorption, dispersion, resonance fluorescence and vacuum fields. This model describes quantum jumps by the entanglement between the photo...

Pakula, R A

2004-01-01

233

Radiative divertor modelling for ITER and TPX  

International Nuclear Information System (INIS)

[en] The B2.5 code for two-dimensional multi-species fluid modelling of the tokamak edge plasma is described and is applied for a parameter study of the effect of impurity seeding in ITER and TPX. Our modelling indicates that ITER must operate at an edge density of about 6.0.1019/m3 and the extended performance TPX must operate at an edge density of about 5.0.1019/m3 in order to obtain a robust divertor solution based on impurity radiatioon from the edge plasma only at neon concentration below 0.6% or argon concentration below 0.4%. For both devices, a high-recycling divertor solution relying on impurity radiation from core and edge together appears very credible. (orig.)

1996-01-01

234

Radiative divertor modelling for ITER and TPX  

Energy Technology Data Exchange (ETDEWEB)

The B2.5 code for two-dimensional multi-species fluid modelling of the tokamak edge plasma is described and is applied for a parameter study of the effect of impurity seeding in ITER and TPX. Our modelling indicates that ITER must operate at an edge density of about 6.0.10{sup 19}/m{sup 3} and the extended performance TPX must operate at an edge density of about 5.0.10{sup 19}/m{sup 3} in order to obtain a robust divertor solution based on impurity radiatioon from the edge plasma only at neon concentration below 0.6% or argon concentration below 0.4%. For both devices, a high-recycling divertor solution relying on impurity radiation from core and edge together appears very credible. (orig.)

Braams, B.J. [New York Univ., NY (United States). Courant Inst.

1996-08-01

235

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

236

Mathematical modeling of heat transfer between the plant seedling and the environment during a radiation frost  

Directory of Open Access Journals (Sweden)

Full Text Available The power of the internal heat source sufficient to maintain a positive temperature of plants during one of the possible form of cold stress - radiation frost was determined with the help of numerical simulation.The simulation of unsteady heat transfer in the soil-plant-air system in the conditions of radiation frost showed that the the ground part of plants is cooling most rapidly, and this process is partially slowed down by the natural-convection heat transfer with warmer air. If the frost is not continuous, the radiative cooling is the main danger for plant. The necessary power of heat-production inside plant that allows it to avoid hypothermia depends both on natural conditions and the size of the plant. For plants with a typical diameter of the stem about 2 mm this heat-production should be from 50 to 100 W / kg. Within 2 hours a total amount of heat about 0.5 MJ / kg in the plant should be allocated. Larger plants will have a smaller surface to mass ratio, and the maintaining of it's temperature will require a lower cost of nutrients per unit, accordingly. Modeling of the influence of plant surface trichomes presence on the process of its cooling showed that the role of trichomes in the protection of plants from hypothermia during radiation frost usually is negative due to the fact that the presence of trichomes increases the radiative heat transfer from the plant and the impediment in air movement near the plant reduces heat flux entering the plant from a warmer air. But in cases where the intensity of heat generation within the plant is sufficient for the maintenance of the plant temperature higher than the air temperature, the presence of trichomes impairs heat transfer from plant to air, and therefore contributes to a better heating of plants.

Finnikov K.A.; A.V. Minakov; A.A. Dekterev; A.A. Gavrilov; A.M. Korzun; V.K. Voinikov; A.V. Kolesnichenko

2010-01-01

237

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

238

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

Energy Technology Data Exchange (ETDEWEB)

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. (author)

Rehman, Shafiqur [Engineering Analysis Section, Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, Box 767, Dhahran 31261 (Saudi Arabia); Mohandes, Mohamed [Electrical Engineering Department, King Fahd University of Petroleum and Minerals (Saudi Arabia)

2008-02-15

239

The discovery of Cherenkov radiation and its use in the detection of extensive air showers  

International Nuclear Information System (INIS)

Cascades of charged particles are created when high-energy cosmic rays enter the earth's atmosphere: these 'extensive air-showers' are studied to gain information on the energy spectrum, arrival direction distribution and mass composition of the particles above 1014eV where direct observations using instruments carried by balloons or satellites become impractical. Detection of light in the visible and ultra-violet ranges of the electromagnetic spectrum plays a key role in this work, the two processes involved being the emission of Cherenkov light and the production of fluorescence radiation. In this paper I will outline some of the history of the discovery of the Cherenkov process and describe the use to which it has been put in the study of extensive air-showers at ground level.

2011-01-01

240

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

 
 
 
 
241

The Dutch standard on the description of air pollution models  

International Nuclear Information System (INIS)

This standard establishes requirements which the description of mathematical models for air quality has to meet. The standard is applicable to models which assist in calculating the concentration of compounds in the air and/or the deposition. Users should be able to judge the usefulness of a mathematical model for their own use on the basis of its description. This is often necessary for granting licences or policy planning. Equipment, software and other requirements are not given. The description of a mathematical model should give the user a good insight into the value of the model and the results obtained. To do this the field of application and the underlying scientific concepts should be clearly described. Besides the results of possible validation procedures the way in which broader acceptance is aimed at and the degree to which this is achieved has to be reflected. (au).

1992-01-01

242

Multimedia modeling of air pollutants in green roof systems  

Energy Technology Data Exchange (ETDEWEB)

Green roofs remove pollutants from the air and can provide significant health benefits. This study used a multimedia fugacity-based model to investigate the fate of atmospheric contaminants in a green roof system. The sequestering emissions designable uptake model (SEDUM) incorporated air, soil media, and vegetation compartments within a steady-state, non-equilibrium, probabilistic model in order to measure the uptake capacity of green roofs and determine potential impacts to water quality. Results of the study demonstrated that reactive nitrogen species were retained within the vegetation and soil media of a green roof system. The model also showed that green roofs decrease concentrations of nitric acid (HNO{sub 3}) and nitrogen oxides (NO{sub 3}) in storm water by 47 per cent. Results of the model correlated with results obtained during experimental studies. The tool will be used to assist policy-makers in effective decision-making. 35 refs.

Clark, C. [Argonne National Laboratory, Argonne, IL (United States); Adriaens, P.; Lastoskie, C. [Michigan State Univ., East Lansing, MI (United States)

2009-07-01

243

Measurement and modelling of neon radiation profiles in radiating boundary discharges in ASDEX upgrade  

International Nuclear Information System (INIS)

[en] The radiation and transport characteristics of ASDEX Upgrade discharges with a neon driven radiative mantle are modelled using a 1-D radial impurity transport code that has been coupled to a simple divertor model describing particle recycling and pumping. The code is well suited to describe the measured impurity line radiation, total, soft X-ray and bremsstrahlung radiation in regions of the plasma which are not dominated by two dimensional effects. The recycling and pumping behaviour of neon as well as the bulk transport of neon for radiative boundary scenarios are discussed. (orig.)

1996-01-01

244

Measurement and modelling of neon radiation profiles in radiating boundary discharges in ASDEX upgrade  

Energy Technology Data Exchange (ETDEWEB)

The radiation and transport characteristics of ASDEX Upgrade discharges with a neon driven radiative mantle are modelled using a 1-D radial impurity transport code that has been coupled to a simple divertor model describing particle recycling and pumping. The code is well suited to describe the measured impurity line radiation, total, soft X-ray and bremsstrahlung radiation in regions of the plasma which are not dominated by two dimensional effects. The recycling and pumping behaviour of neon as well as the bulk transport of neon for radiative boundary scenarios are discussed. (orig.)

Dux, R.; Kallenbach, A.; Bessenrodt-Weberpals, M.; Behringer, K.; Bosch, H.S.; Fuchs, J.C.; Gehre, O.; Mast, F.; Poschenrieder, W.; Murmann, H.; Salzmann, H.; Schweinzer, J.; Suttrop, W. [MPI fuer Plasmaphysik, EURATOM Association, Garching and Berlin (Germany); ASDEX Upgrade- and NI-Team

1996-02-01

245

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

246

Damage to air-dried human blood cells and tissue sections by synchrotron radiation  

International Nuclear Information System (INIS)

Damage to unfixed, air-dried human blood cells and tissues caused by synchrotron radiation was studied by scanning electron microscopy (SEM) and by light microscopy (LM). Morphological changes were found in unstained cell specimens after irradiation with photon fluences around 2 x 109 photons/cm2 at an average energy of 15.2 keV. At lower fluences (7 x 1018 photons/cm2), morphological changes in irradiated cells are seen by LM after, but not before, staining by a standard hematological technique. (orig.).

1984-01-01

247

Damage to air-dried human blood cells and tissue sections by synchrotron radiation  

Energy Technology Data Exchange (ETDEWEB)

Damage to unfixed, air-dried human blood cells and tissues caused by synchrotron radiation was studied by scanning electron microscopy (SEM) and by light microscopy (LM). Morphological changes were found in unstained cell specimens after irradiation with photon fluences around 2 x 10Z photons/cmS at an average energy of 15.2 keV. At lower fluences (7 x 10 Y photons/cmS), morphological changes in irradiated cells are seen by LM after, but not before, staining by a standard hematological technique. (orig.).

Slatkin, D.N.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Warren, J.B.; Finkel, G.C.

1984-11-15

248

Damage to air-dried human blood cells and tissue sections by synchrotron radiation  

Energy Technology Data Exchange (ETDEWEB)

Damage to unfixed, air-dried human blood cells and tissues caused by synchrotron radiation was studied by scanning electron microscopy (SEM) and by light microscopy (LM). Morphological changes were found in unstained cell specimens after irradiation with photon fluences around 2 x 10/sup 9/ photons/cm/sup 2/ at an average energy of 15.2 keV. At lower fluences (7 x 10/sup 18/ photons/cm/sup 2/), morphological changes in irradiated cells are seen by LM after, but not before, staining by a standard hematological technique.

Slatkin, D.N.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Warren, J.B. (Brookhaven National Lab., Upton, NY (USA)); Finkel, G.C. (State Univ. of New York, Stony Brook (USA). Health Science Center)

1984-11-15

249

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

UK PubMed Central (United Kingdom)

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 observational data are scarce, respectively. Such method is very efficient for similar assessment studies due to continuous spatio-temporal coverage of the obtained results. In the study the values of the concentration of the harmful substances sulphur dioxide, (SO2), nitrogen dioxide (NO2), particulate matter - coarse (PM10) and fine (PM2.5) fraction, ozone (O3), carbon monoxide (CO) and ammonia (NH3) in the surface layer obtained from modelling simulations with resolution 10 km on hourly bases are taken to calculate the necessary statistical quantities which are used for comparison with the corresponding critical levels, prescribed in the EC directives. For part of them (PM2.5, CO and NH3) this is done for first time with such resolution. The computational grid covers Bulgaria entirely and some surrounding territories and the calculations are made for every year in the period 1991-2000. The averaged over the whole time slice results can be treated as representative for the air quality situation of the last decade of the former century.

Chervenkov H

2013-12-01

250

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

Science.gov (United States)

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 observational data are scarce, respectively. Such method is very efficient for similar assessment studies due to continuous spatio-temporal coverage of the obtained results. In the study the values of the concentration of the harmful substances sulphur dioxide, (SO2), nitrogen dioxide (NO2), particulate matter - coarse (PM10) and fine (PM2.5) fraction, ozone (O3), carbon monoxide (CO) and ammonia (NH3) in the surface layer obtained from modelling simulations with resolution 10 km on hourly bases are taken to calculate the necessary statistical quantities which are used for comparison with the corresponding critical levels, prescribed in the EC directives. For part of them (PM2.5, CO and NH3) this is done for first time with such resolution. The computational grid covers Bulgaria entirely and some surrounding territories and the calculations are made for every year in the period 1991-2000. The averaged over the whole time slice results can be treated as representative for the air quality situation of the last decade of the former century. PMID:23556142

Chervenkov, Hristo

2013-03-01

251

Modeling the macroeconomic impact of air-pollution abatement  

Energy Technology Data Exchange (ETDEWEB)

A comprehensive model framework is presented for assessing the macroeconomic impact of air-pollution-control regulations. The paper first reviews the capabilities, projections, and biases of previous models. Next, the set of important relationships affecting the economic outcome of environmental regulation is identified. A unifying model framework, flexible enough to incorporate alternative assumptions about impact stimuli, is then presented. A pared-down version of the model is used to illustrate the sensitivity of assessment results to various causal determinants and assumptions in the hope of pointing to fruitful directions of additional modeling efforts and empirical research on the subject. 53 references, 1 figure, 3 tables.

Rose, A.

1983-11-01

252

Ozone air quality model development in the US  

Energy Technology Data Exchange (ETDEWEB)

Air quality models for ozone have been under development and in operation for over twenty years in the United States. The authors are presently in the third generation of such models. The defining feature of third generation models is that they are fully multi-scale, able to simulate the relevant processes leading to ozone accumulation on scales ranging from point source size to continental. The key feature of multi-scale models is the ability to nest subdomains of finer grid resolution inside domains of coarser resolution, providing an appropriate level of detail for different portions of the modeling domain.

Schere, K.

1996-12-31

253

Galactic cosmic radiation exposure and associated health risks for air carrier crewmembers  

Energy Technology Data Exchange (ETDEWEB)

The dose equivalent to air carrier crewmembers from galactic cosmic radiation was estimated for each of 32 nonstop flights on a variety of routes to and from, or within, the contiguous United States. Flying times were from 0.4 to 13 hours. The annual dose equivalents received on the flights ranged from 0.2 to 9.1 mSv (20 to 910 mrem), or 0.4 to 18% of the recommended annual limit for occupational exposure of an adult. We reviewed some of the characteristics of galactic and solar cosmic radiation and provided example calculations for estimating radiation-induced risks of fatal cancer, genetic defects and harm to an embryo or fetus. The estimated increased risk of dying from cancer because of galactic radiation exposure received during 20 years of flying ranged from 0.1 to 5 in 1,000. For the adult U.S. population the risk of dying from cancer is about 220 in 1,000.

Friedberg, W.; Faulkner, D.N.; Snyder, L.; Darden, E.B. Jr.; O' Brien, K. (Federal Aviation Administration, Oklahoma City, OK (USA))

1989-11-01

254

Pollutant dispersion models for issues of air pollution control  

International Nuclear Information System (INIS)

14 papers entered separately into the data base were presented at the meeting for application-oriented dispersion models for issues of air pollution control. These papers focus on fields of application, availability of required input data relevant to emissions and meteorology, performance and accuracy of these methods and their practicability. (orig./PW)

1984-05-10

255

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

256

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 ...

257

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...

258

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; Natalia G. Inozemtseva

2006-01-01

259

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 ( {Rs=A+B\\cdot R{{s}_0}{{{( {{T_{max }}-{T_{min }}} )}}^C}} ) 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.

2013-04-01

260

A backward-time stochastic Lagrangian air quality model  

Science.gov (United States)

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

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

2012-07-01

 
 
 
 
261

Air quality along motorways. Measuring and modelling calculations  

International Nuclear Information System (INIS)

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

2004-01-01

262

NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling.  

Science.gov (United States)

Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and Natio...

A. Biazar H. Peterson L. Wang M. Khan W. Koshak

2011-01-01

263

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; J. Gasore

2009-01-01

264

The use of the Cherenkov radiation and the fluorescence light to calibrate the energy of giant air showers  

CERN Multimedia

In terms of the quark-gluon string model the analysis of the classic procedure to estimate the energy of giant air showers with help of the parameter s(600) (a density of energy deposition in the scintillator at a distance of 600 m from the shower core) have been carried out. Simulations of the signal s(600) with help of the CORSIKA code in terms of the hybrid scheme show energy estimates which are approximately a factor of 1.6 times lower than adopted at the Yakutsk array. The energy estimates calculated with the help of the Cherenkov radiation coincide with the experimental data. Simulations of deposited energy distributions in the atmosphere with help of the GEANT4 code and the CORSIKA code show that more than 20% of this energy may be deposited at distances above 100 m from the shower axis.

Dedenko, L G; Roganova, T M; Fedorova, G F; Fedunin, E Y; Shozieev, G P

2007-01-01

265

Air pollution dispersion models for human exposure predictions in London.  

UK PubMed Central (United Kingdom)

The London household survey has shown that people travel and are exposed to air pollutants differently. This argues for human exposure to be based upon space-time-activity data and spatio-temporal air quality predictions. For the latter, we have demonstrated the role that dispersion models can play by using two complimentary models, KCLurban, which gives source apportionment information, and Community Multi-scale Air Quality Model (CMAQ)-urban, which predicts hourly air quality. The KCLurban model is in close agreement with observations of NO(X), NO(2) and particulate matter (PM)(10/2.5), having a small normalised mean bias (-6% to 4%) and a large Index of Agreement (0.71-0.88). The temporal trends of NO(X) from the CMAQ-urban model are also in reasonable agreement with observations. Spatially, NO(2) predictions show that within 10's of metres of major roads, concentrations can range from approximately 10-20 p.p.b. up to 70 p.p.b. and that for PM(10/2.5) central London roadside concentrations are approximately double the suburban background concentrations. Exposure to different PM sources is important and we predict that brake wear-related PM(10) concentrations are approximately eight times greater near major roads than at suburban background locations. Temporally, we have shown that average NO(X) concentrations close to roads can range by a factor of approximately six between the early morning minimum and morning rush hour maximum periods. These results present strong arguments for the hybrid exposure model under development at King's and, in future, for in-building models and a model for the London Underground.Journal of Exposure Science and Environmental Epidemiology advance online publication, 27 February 2013; doi:10.1038/jes.2013.6.

Beevers SD; Kitwiroon N; Williams ML; Kelly FJ; Ross Anderson H; Carslaw DC

2013-02-01

266

Controlling indoor air pollution from tobacco smoke: models and measurements  

Energy Technology Data Exchange (ETDEWEB)

The effects of smoking rate, ventilation, surface deposition, and air cleaning on the indoor concentrations of respirable particulate matter and carbon monoxide generated by cigarette smoke are examined. A general mass balance model is presented which has been extended to include the concept of ventilation efficiency. Following a review of the source and removal terms associated with respirable particles and carbon monoxide, model predictions to various health guidelines are compared. 20 references, 1 figure.

Offermann, F.J.; Girman, J.R.; Sextro, R.G.

1984-07-01

267

Spatial distribution of emissions to air – 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 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.

Plejdrup, Marlene Schmidt; Gyldenkærne, Steen

2011-01-01

268

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

269

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.

2009-01-01

270

76 FR 31800 - Airworthiness Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes  

Science.gov (United States)

...Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes AGENCY: Federal Aviation Administration...the Viking Air Limited Model DHC-3 (Otter) airplanes equipped with a Honeywell...Viking Aircraft Limited Model DHC-3 (Otter) airplanes, all serial numbers,...

2011-06-02

271

CFD modelling of moisture interactions between air and constructions  

DEFF Research Database (Denmark)

There is a strong demand for accurate moisture modelling since moisture poses a risk for both the constructions and the indoor climate. Thus, in this investigation there is special focus on moisture modelling. The paper describes a new model based on a CFD tool that is enhanced to include both detailed modelling of airflows in rooms and heat and moisture transfer in walls by applying them as fluid walls. In a 3D configuration the impact of different boundary conditions are investigated and the results are discussed. The changes of boundary conditions that are studied are velocity, moisture and temperature conditions for room air.

Mortensen, Lone Hedegaard; Woloszyn, Monika

2005-01-01

272

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)

273

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

UK PubMed Central (United Kingdom)

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

Hachisuka A; Kimura Y; Nakamura R; Teshima R

2011-01-01

274

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

International Nuclear Information System (INIS)

[en] 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

275

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

International Nuclear Information System (INIS)

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

2012-12-31

276

Caenorhabditis elegans: a model to monitor bacterial air quality.  

UK PubMed Central (United Kingdom)

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 C; Groboillot A; Lesouhaitier O; Morin JP; Orange N; Feuilloley MJ

2011-01-01

277

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; Groboillot Anne; Lesouhaitier Olivier; Morin Jean-Paul; Orange Nicole; Feuilloley Marc JG

2011-01-01

278

Residential air conditioner dynamic model for direct load control  

Energy Technology Data Exchange (ETDEWEB)

Accurate single customer models are vital to the development of aggregate dynamic load models which can predict response to direct load control actions. Without such aggregate models, optimal scheduling of direct load control actions in a manner which accounts for constraints upon customer comfort is not possible. A dynamic model of the response of a single residential air conditioner load to weather conditions is developed. The model's performance is evaluated using data obtained from the Athens Automation and Control Experiment (AACE), in Athens, Tennessee, and some novel approaches to the determination of the parameters of a customer's thermal envelope model are discussed. The model is used to make a preliminary assessment of the effect of the level of detail upon model accuracy. For the limited number of customers with suitable data and survey information who were available in the experiment, the variability of parameters and responses is assessed.

Bargiotas, D.; Birdwell, J.D. (Dept. of Electrical and Computer Engineering, Univ. of Tennessee, Knoxville, TN (US))

1988-10-01

279

Multiple-model algorithm for passive ranging and air-to-air missile guidance systems  

Science.gov (United States)

Passive guidance schemes that employ measurement of relative bearing to the target via an angle-or-arrival mechanism (such as optical telescope or radar antenna) offers several strategic benefits but suffer from the unavailability of measurement of range or range-rate. Passive ranging, i.e., estimation of range information from available measurements, is fraught with many technical challenges, and particularly in an air-to-air missile guidance context is complicated by a stubborn observability problem. As a missile maneuvers for an optimal intercept solutions, range and range-rate observability are degraded and, in the presence of measurement noise and target acceleration, become completely unobservable. Available schemes that typically employ extended Kalman filter solutions perform well against non-maneuvering targets but suffer estimation bias and divergence as intercept is approached. Interactive Multiple Model solutions promoted in prior works show promise in removing estimation bias due to target maneuver but have so far been restricted to active ranging problems. In this paper we shall present a novel Multiple Maneuver Model Filter (termed M3F in the following) that employs a suite of constant acceleration models in order to reliably estimate any target maneuver executed in the vertical as well as the horizontal plane. To quantitatively demonstrate the tracking performance of this filter, a set of benchmark tracking scenarios which present a broad range of problems relevant to passive ranging in an air-to-air missile context is also developed in this work. It should be emphasized that while several benchmark tracking problems in a surveillance radar context are recently developed, especially for testing the beam steering efficiency of a phased array system, these are not particularly useful for evaluating the performance of an air-to-air missile guidance scheme, and hence the benchmark scenarios developed in this work are of independent interest. Simulations of the M3F against the benchmark cases are also included to demonstrate the superior performance offered by the present algorithm in reducing estimation bias compared to existing techniques.

Mosier, Daniel; Sundareshan, Malur K.

2001-11-01

280

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

 
 
 
 
281

Impacts of contaminant storage on indoor air quality: Model development  

Science.gov (United States)

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

Sherman, Max H.; Hult, Erin L.

2013-06-01

282

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

Scientific Electronic Library Online (English)

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

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

2011-02-01

283

Predictive Model of Radiative Neutrino Masses  

CERN Document Server

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 Z_4 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 \\delta_{CP} = \\pi; and the effective mass in neutrinoless double beta decay lies in a narrow range, m_{\\beta \\beta} = (17.6 - 18.5) meV. The ratio of vacuum expectation values of the two Higgs doublets, tan\\beta, 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 non-standard neutral Higgs bosons, if t...

Babu, K S

2013-01-01

284

Radiative neutrino decay in superstring models  

Energy Technology Data Exchange (ETDEWEB)

The rate for the radiative decay of neutrinos is calculated in E/sub 6/ superstring models with light colour triplet isosinglets h and Planck constant. In contrast to the standard model, the rate is not suppressed either by the GIM mechanism or by helicity matching. Comparison with astrophysical data allows one to set an upper limit on the Yukawa couplings anti lambdaQLanti h and lambdad/sup c/v/sup c/h. Taking. Msub(h,anti h)=O(100 GeV) it is found that lambda/sub e,..mu../, anti lambda/sub e,..mu../<10/sup -3/-10/sup -4/, in the range 10-100 eV. From the cosmological requirement of not photo-ionizing light elements after nucleosynthesis, it follows that the ..nu../sub tau/ must lie in the same mass range and consequently lambda/sub tau/, anti lambda<10/sup -3/. (orig./HSI).

Enqvist, K.; Maalampi, J.

1986-11-20

285

3D Atmospheric Radiative Transfer for Cloud System-Resolving Models: Forward Modelling and Observations  

Energy Technology Data Exchange (ETDEWEB)

Utilization of cloud-resolving models and multi-dimensional radiative transfer models to investigate the importance of 3D radiation effects on the numerical simulation of cloud fields and their properties.

Howard Barker; Jason Cole

2012-05-17

286

Development of a hydrodynamic model for air-lift reactors  

Directory of Open Access Journals (Sweden)

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

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

2000-01-01

287

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

Energy Technology Data Exchange (ETDEWEB)

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 in the evaporator and condenser, system mass effects, air side heat transfer on the condenser/evaporator, vehicle speed effects, temperature-dependent properties, and integration with a simplified cabin thermal model. It has demonstrated robust and powerful system design optimization capabilities. Single-variable and multiple variable design optimizations have been performed and are presented. Various system performance parameters can be optimized, including system COP, cabin cool-down time, and system heat load capacity. This work presents this new transient A/C system analysis and optimization tool and shows some high-level system design conclusions reached to date. The work focuses on R-134a A/C systems, but future efforts will modify the model to investigate the transient performance of alternative refrigerant systems such as carbon dioxide systems. NREL is integrating its transient air conditioning model into NRELs ADVISOR vehicle system analysis software, with the objective of simultaneously optimizing A/C system designs within the overall vehicle design optimization.

Hendricks, T. J.

2001-06-01

288

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.

Matthias Rempel; Rolf Schlichenmaier

2011-01-01

289

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

290

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

International Nuclear Information System (INIS)

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

2005-01-01

291

Comparison of the standards for air kerma of the KRISS and the BIPM for 137Cs gamma radiation  

International Nuclear Information System (INIS)

A direct comparison of the standards for air kerma of the Korea Research Institute of Standards and Science (KRISS), Korea, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 137Cs radiation beam of the BIPM in August 2010. The result, expressed as a ratio of the KRISS and the BIPM standards for air kerma, is 0.9986 with a combined standard uncertainty of 2.2 * 10-3. (authors)

2010-01-01

292

Modelling the regional effects of climate change on air quality; Modelisation des effets regionaux du changement climatique sur la qualite de l'air  

Energy Technology Data Exchange (ETDEWEB)

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

Giorgi, F. [International Centre for Theoretical Physics (ICTP), Trieste (Italy); Meleux, F. [Institut national de l' Environnement Industriel et des Risques (INERIS), 60 6 Verneuil en Halatte (France)

2007-10-15

293

Review of reconstruction of radiation incident air kerma by measurement of absorbed dose in tooth enamel with EPR.  

UK PubMed Central (United Kingdom)

Electron paramagnetic resonance dosimetry with tooth enamel has been proved to be a reliable method to determine retrospectively exposures from photon fields with minimal detectable doses of 100 mGy or lower, which is lower than achievable with cytogenetic dose reconstruction methods. For risk assessment or validating dosimetry systems for specific radiation incidents, the relevant dose from the incident has to be calculated from the total absorbed dose in enamel by subtracting additional dose contributions from the radionuclide content in teeth, natural external background radiation and medical exposures. For calculating organ doses or evaluating dosimetry systems the absorbed dose in enamel from a radiation incident has to be converted to air kerma using dose conversion factors depending on the photon energy spectrum and geometry of the exposure scenario. This paper outlines the approach to assess individual dose contributions to absorbed dose in enamel and calculate individual air kerma of a radiation incident from the absorbed dose in tooth enamel.

Wieser A

2012-03-01

294

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

295

Modeling classical and quantum radiation from laser-plasma accelerators  

Science.gov (United States)

The development of models and the “Virtual Detector for Synchrotron Radiation” (vdsr) code that accurately describe the production of synchrotron radiation are described. These models and code are valid in the classical and linear (single-scattering) quantum regimes and are capable of describing radiation produced from laser-plasma accelerators (LPAs) through a variety of mechanisms including betatron radiation, undulator radiation, and Thomson/Compton scattering. Previous models of classical synchrotron radiation, such as those typically used for undulator radiation, are inadequate in describing the radiation spectra from electrons undergoing small numbers of oscillations. This is due to an improper treatment of a mathematical evaluation at the end points of an integration that leads to an unphysical plateau in the radiation spectrum at high frequencies, the magnitude of which increases as the number of oscillation periods decreases. This is important for betatron radiation from LPAs, in which the betatron strength parameter is large but the number of betatron periods is small. The code vdsr allows the radiation to be calculated in this regime by full integration over each electron trajectory, including end-point effects, and this code is used to calculate betatron radiation for cases of experimental interest. Radiation from Thomson scattering and Compton scattering is also studied with vdsr. For Thomson scattering, radiation reaction is included by using the Sokolov method for the calculation of the electron dynamics. For Compton scattering, quantum recoil effects are considered in vdsr by using Monte Carlo methods. The quantum calculation has been benchmarked with the classical calculation in a classical regime.

Chen, M.; Esarey, E.; Geddes, C. G. R.; Schroeder, C. B.; Plateau, G. R.; Bulanov, S. S.; Rykovanov, S.; Leemans, W. P.

2013-03-01

296

Research on Dependable Ionizing Radiation Protection based on Model i*  

Directory of Open Access Journals (Sweden)

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

Tan Hai; Shahnawaz Talpur; Imran Ali Qureshi

2013-01-01

297

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 skin, causing a cooling effect, at least in low-rise buildings. One of the most important factors affecting the thermal effects of ventilated façades 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 façade 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.

Miguel Mora Pérez, Gonzalo López Patiño, P. Amparo López Jiménez

2013-01-01

298

Linkage effects in a model for cell survival after radiation  

International Nuclear Information System (INIS)

A thermodynamic treatment for the effects of radiation on cell survival is proposed. The treatment is an extension of the linear-quadratic model following the principles of linkage thermodynamics. Linkage effects between chemical binding to DNA and radiation action are considered, along with the synergism between different types of radiations. A simple mathematical condition is found for the additivity of radiation doses that result in an isoeffect. The resolvability of the model parameter is investigated by simulations and statistical analysis of the distributions obtained. (author). 22 refs.; 3 figs.

1989-01-01

299

Evaluation of Rural Air Quality Simulation Models. Addendum A: Muskingum River Data Base.  

Science.gov (United States)

The addendum provides additional information regarding the performance of four rural air quality simulation models using SO2 air quality and a modelers data base assembled for the Muskingum River Power Plant. The report contains numerous tabulations of ea...

W. M. Cox G. K. Moss

1985-01-01

300

Weak radiative baryon decays in the Skyrme model  

Energy Technology Data Exchange (ETDEWEB)

A Skyrme-model calculation of weak radiative baryon octet and decuplet decays is presented, based on a Lagrangian describing weak nonleptonic decays of mesons previously discussed by Donoghue and collaborators. There are no free parameters in the Skyrme-model predictions for weak radiative decays, as all necessary parameters are obtained from other contexts. The predictions of the Skyrme model for the weak radiative baryon decays are in good qualitative agreement with experiment, except for ..sigma../sup +/..-->..p..gamma.., where however the model involves substantial cancellations among terms which are sensitive to small changes of input parameters.

Kao, W.F.; Schnitzer, H.J.

1988-04-01

 
 
 
 
301

Skyrme model predictions for weak radiative decays of baryons  

Energy Technology Data Exchange (ETDEWEB)

A Skyrme model calculation of weak radiative baryon decays is presented, based on a lagrangian describing weak non-leptonic decays of mesons previously discussed by Donoghue et al. There are no free parameters in the Skyrme model predictions for weak radiative decays, as all necessary parameters are obtained from other contexts. The predictions of the Skyrme model for the weak radiative baryon decays are in good agreement with experiment, except for ..sigma../sup +/ -> P/sub ..gamma../, where however the model involves substantial concellations among terms, which are sensitive to small changes of input parameters.

Kao, W.F.; Schnitzer, J.

1987-01-15

302

Numerical modelling of radiation Marshak Waves  

International Nuclear Information System (INIS)

The importance of radiation transport in inertial confinement fusion (ICF) target design is discussed. It is shown that a self similar solution of non-linear heat conduction can be used to estimate the penetration depth of radiation thermal waves (Marshak Waves) in ion-beam ICF pellets. An improved numerical treatment of non-linear heat conduction has been incorporated into the hydrodynamic code MEDUSA-KA to simulate radiation transport in ICF target design studies. The numerical results have been checked against self-similar solutions and a comparison between the two is presented and good agreement is found. The necessity of using a high-z radiation shield to protect the fuel from radiative preheat is also discussed. (author).

1984-01-01

303

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

International Nuclear Information System (INIS)

[en] 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

304

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

305

Evaluation of radiation scheme performance within chemistry climate models  

Science.gov (United States)

This paper evaluates global mean radiatively important properties of chemistry climate models (CCMs). We evaluate stratospheric temperatures and their 1980-2000 trends, January clear sky irradiances, heating rates, and greenhouse gas radiative forcings from an offline comparison of CCM radiation codes with line-by-line models, and CCMs' representation of the solar cycle. CCM global mean temperatures and their change can give an indication of errors in radiative transfer codes and/or atmospheric composition. Biases in the global temperature climatology are generally small, although five out of 18 CCMs show biases in their climatology that likely indicate problems with their radiative transfer codes. Temperature trends also generally agree well with observations, although one model shows significant discrepancies that appear to be due to radiation errors. Heating rates and estimated temperature changes from CO2, ozone, and water vapor changes are generally well modeled. Other gases (N2O, CH4, and CFCs) have only played a minor role in stratospheric temperature change, but their heating rates have large fractional errors in many models. Models that do not account for variations in the spectrum of solar irradiance cannot properly simulate solar-induced variations in stratospheric temperature. The combined long-lived greenhouse gas global annual mean instantaneous net radiative forcing at the tropopause is within 30% of line-by-line models for all CCM radiation codes tested. Problems remain in simulating radiative forcing for stratospheric water vapor and ozone changes with errors between 3% and 200% compared to line by line models. The paper makes recommendations for CCM radiation code developers and future intercomparisons.

Forster, Piers M.; Fomichev, Victor I.; Rozanov, Eugene; Cagnazzo, Chiara; Jonsson, Andreas I.; Langematz, Ulrike; Fomin, Boris; Iacono, Michael J.; Mayer, Bernhard; Mlawer, Eli; Myhre, Gunnar; Portmann, Robert W.; Akiyoshi, Hideharu; Falaleeva, Victoria; Gillett, Nathan; Karpechko, Alexey; Li, Jiangnan; Lemennais, Perrine; Morgenstern, Olaf; OberläNder, Sophie; Sigmond, Michael; Shibata, Kiyotaka

2011-05-01

306

The influence of the solar radiation model on the calcutated solar radiation from a horizontal surface to a tilted surface  

DEFF Research Database (Denmark)

Measured solar radiation data are most commonly available as total solar radiation on a horizontal surface. When using solar radiation measured on horizontal to calculate the solar radiation on tilted surfaces and thereby the thermal performance of different applications such as buildings and solar heating systems, different solar radiation models can be used. The calculation of beam radiation from a horizontal surface to a tilted surface can be done exactly whereas different solar radiation models can calculate the sky diffuse radiation. The sky diffuse radiation can either be assumed evenly distributed over the entire sky dome and calculated as pure isotropic radiation or by anisotropic radiation models that also uses contribution from circumsolar radiation in the calculation or by anisotropic radiation models that apart from the isotropic and circumsolar contribution uses horizon brightening in the calculation. The weather data are measured at the solar radiation measurement station, SMS at the Departmentof Civil Engineering at the Technical University of Denmark. In this study the weather data are combined with solar collector calculations based on solar collector test carried out at Solar Energy Center, SEC, Denmark. With measured solar radiation on horizontal and the different solar radiation processing models the total radiation is calculated on differently tilted and oriented surfaces and compared with the measured solar radiation on the different surfaces. Further, the impact on the yearly thermal performances of a solar collector using the different solar radiation processing models is investigated. The study shows that the isotropic diffuse radiation model is underestimating the diffuse radiation from south and overestimating the diffuse radiation from north, while the anisotropic models give a better estimate on the diffuse radiation from all directions.

Andersen, Elsa; Lund, Hans

2004-01-01

307

Characterization of air-exposure/activation cycles of porous Ti-Zr-V getter film using synchrotron radiation photoemission spectroscopy  

International Nuclear Information System (INIS)

Highly porous TiZrV films on (100) Si wafers were used to study the oxidation state of a film surface after three gas-adsorption/activation cycles using synchrotron radiation photoemission spectroscopy (SRPES). The oxidation state and composition of porous TiZrV film are highly affected by the present conditions of air-exposure/activation cycles. In the porous TiZrV films after activation treatment, the C content on the surface of the films gradually increased with increasing air-exposure/activation cycles. In the porous TiZrV film after air-exposure treatment, the O content on the surface of the films decreased with increasing of air-exposure/activation cycles. The concentration of Zr on the film surface increased with increasing of air-exposure/activation cycles. These results are caused by the formation of metal carbides on the film surface.

2009-05-01

308

Ion recombination in parallel-plate free-air ionization chambers for synchrotron radiation  

Energy Technology Data Exchange (ETDEWEB)

The saturation characteristics of two sizes of parallel-plate free-air ionization chambers were investigated for synchrotron radiation at bending-magnet, wiggler and undulator beamlines of SPring-8. The gaps of the electrodes were 4.2 and 85 mm. The monoenergetic photon energies ranged from 10 to 115.56 keV and the air kerma rates from 0.2 mGy s{sup -1} to 150 kGy s{sup -1}. Ion recombination at the high dose rate was found to be smaller than that predicted by Boag's expression, which was based on volume recombination, and the difference increased with an applied electric field. In the high dose rate region, the reciprocal of the current was linear to the reciprocal of the electric field near saturation, which represented the occurrence of initial recombination and diffusion loss. At the low electric field and the low dose rate, the reciprocal of the current was linear to the reciprocal of the square of the electric field. The reduction of total ion recombination was attributed to the shift of the contribution from volume recombination to initial recombination and diffusion loss.

Nariyama, Nobuteru [Japan Synchrotron Radiation Research Institute, Beamline Division, Kouto 1-1-1, Sayo, Hyogo 679-5198 (Japan)

2006-10-21

309

Air pollutants and energy pathways; Extending models for abatement strategies  

International Nuclear Information System (INIS)

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

2001-01-01

310

A kinetic model of radiating electrons  

Science.gov (United States)

A kinetic theory is developed to describe radiating electrons whose motion is governed by the Lorentz-Dirac equation. This gives rise to a generalized Vlasov equation coupled to an equation for the evolution of the physical submanifold of phase space. The pathological solutions of the 1-particle theory may be removed by expanding the latter equation in powers of ? ? q2/6?m. The radiation-induced change in entropy is explored and its physical origin is discussed. As a simple demonstration of the theory, the radiative damping rate of longitudinal plasma waves is calculated.

Noble, A.; Burton, D. A.; Gratus, J.; Jaroszynski, D. A.

2013-04-01

311

Hawking Radiation-A Augmentation Attrition Model  

Directory of Open Access Journals (Sweden)

Full Text Available A system of Hawking radiation that dissipates the energy and mass of black hole is investigated. With the methodology reinforced with the explanations, we write the governing equations with the nomenclature for the system of matter antimatter and concatenate those equations with that of energy and mass of Black hole and Hawking radiation, such concatenation process, ipso facto fait accompli, following the same processual formalities for solvability. Key words: Hawking Radiation; Black Body; Fundamental Forces; Energy; Mass; Matter; Antimatter; Black Hole; Governing Equations

K. N.Prasanna Kumar; B. S. Kiranagi; C. S. Bagewadi

2012-01-01

312

A kinetic model of radiating electrons  

CERN Document Server

A kinetic theory is developed to describe radiating electrons whose motion is governed by the Lorentz-Dirac equation. This gives rise to a generalized Vlasov equation coupled to an equation for the evolution of the physical submanifold of phase space. The pathological solutions of the 1-particle theory may be removed by expanding the latter equation in powers of $\\tau := q^2/ 6\\pi m$. The radiation-induced change in entropy is explored, and its physical origin is discussed. As a simple demonstration of the theory, the radiative damping rate of longitudinal plasma waves is calculated.

Noble, A; Burton, D A; Jaroszynski, D A

2012-01-01

313

Radiation exposure modeling and project schedule visualization  

Energy Technology Data Exchange (ETDEWEB)

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.

Jaquish, W.R.; Enderlin, V.R. [ICF Kaiser Hanford Co., Richland, WA (United States)

1995-10-01

314

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

Science.gov (United States)

...Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes With Supplemental Type Certificate...applies to Viking Air Limited Model DHC-3 (Otter) airplanes equipped with a Honeywell TPE331...for Viking Air Limited Model DHC-3 (Otter) airplanes equipped with a Honeywell...

2011-10-11

315

75 FR 82219 - Airworthiness Directives; Air Tractor, Inc. Models AT-802 and AT-802A Airplanes  

Science.gov (United States)

...Directives; Air Tractor, Inc. Models AT-802 and AT- 802A Airplanes AGENCY: Federal...Tractor, Inc. (Air Tractor) Models AT-802 and AT-802A airplanes. That AD currently...2010), for all Air Tractor Models AT-802 and AT- 802A airplanes. That AD...

2010-12-30

316

Treatment of cloud radiative effects in general circulation models  

International Nuclear Information System (INIS)

The authors participate in the Atmospheric Radiation Measurement (ARM) Program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud overlapping and the cloud optical properties and (2) to study the effects of cloud/radiation-climate interaction on climate simulations. This paper summarizes the project progress since the second ARM Science Team meeting October 26-30, 1992, in Denver, Colorado. Four graduate students participated in the research

1994-01-01

317

Treatment of cloud radiative effects in general circulation models  

Energy Technology Data Exchange (ETDEWEB)

We participate in the Atmospheric Radiation Measurement (ARM) program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud verticle overlapping and layer cloud optical properties, and (2) to study the effects of cloud/radiation-climate interaction on GCM climate simulations. This report summarizes the project progress since the Fourth ARM Science Team meeting February 28-March 4, 1994, in Charleston, South Carolina.

Wang, W.C.; Dudek, M.P.; Liang, X.Z.; Ding, M. [State Univ. of New York, Albany, NY (United States)] [and others

1996-04-01

318

Dark radiation from a unified dark fluid model  

CERN Multimedia

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

319

Spatial and energy distributions of skyshine neutron and gamma radiation from nuclear reactors on the ground-air boundary  

Energy Technology Data Exchange (ETDEWEB)

A set of measurements on skyshine radiation was conducted at two special research reactors. A broad range of detectors was used in the measurements to record neutron and gamma radiations. Dosimetric and radiometric field measurements of the neutrons and gamma quanta of the radiation scattered in the air were performed at distances of 50 to 1000 m from the reactor during different weather conditions. The neutron spectra in the energy range of 1 eV to 10 MeV and the gamma quanta spectra in the range of 0.1-10 MeV were measured. (author)

Orlov, Y.; Netecha, M.E.; Vasiliev, A.P.; Avaev, V.N.; Vasiliev, G.A. [Research and Development Institute of Power Engineering, Moscow (Russian Federation); Zelensky, D.I.; Istomin, Y.L.; Cherepnin, Y.S. [Institute of Atomic Energy of the National Nuclear Center of the Republic of Kazakhstan, Semipalatinsk-21 (Kazakhstan); Nomura, Y. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2000-03-01

320

Spatial and energy distributions of skyshine neutron and gamma radiation from nuclear reactors on the ground-air boundary  

International Nuclear Information System (INIS)

[en] A set of measurements on skyshine radiation was conducted at two special research reactors. A broad range of detectors was used in the measurements to record neutron and gamma radiations. Dosimetric and radiometric field measurements of the neutrons and gamma quanta of the radiation scattered in the air were performed at distances of 50 to 1000 m from the reactor during different weather conditions. The neutron spectra in the energy range of 1 eV to 10 MeV and the gamma quanta spectra in the range of 0.1-10 MeV were measured. (author)

2000-01-01

 
 
 
 
321

Modeling gamma radiation dose in dwellings due to building materials.  

UK PubMed Central (United Kingdom)

A model is presented that calculates the absorbed dose rate in air of gamma radiation emitted by building materials in a rectangular body construction. The basis for these calculations is formed by a fixed set of specific absorbed dose rates (the dose rate per Bq kg(-1) 238U, 232Th, and 40K), as determined for a standard geometry with the dimensions 4 x 5 x 2.8 m3. Using the computer codes Marmer and MicroShield, correction factors are assessed that quantify the influence of several room and material related parameters on the specific absorbed dose rates. The investigated parameters are the position in the construction; the thickness, density, and dimensions of the construction parts; the contribution from the outer leave; the presence of doors and windows; the attenuation by internal partition walls; the contribution from building materials present in adjacent rooms; and the effect of non-equilibrium due to 222Rn exhalation. To verify the precision, the proposed method is applied to three Dutch reference dwellings, i.e., a row house, a coupled house, and a gallery apartment. The averaged difference with MCNP calculations is found to be 4%.

de Jong P; van Dijk W

2008-01-01

322

Modeling gamma radiation dose in dwellings due to building materials.  

Science.gov (United States)

A model is presented that calculates the absorbed dose rate in air of gamma radiation emitted by building materials in a rectangular body construction. The basis for these calculations is formed by a fixed set of specific absorbed dose rates (the dose rate per Bq kg(-1) 238U, 232Th, and 40K), as determined for a standard geometry with the dimensions 4 x 5 x 2.8 m3. Using the computer codes Marmer and MicroShield, correction factors are assessed that quantify the influence of several room and material related parameters on the specific absorbed dose rates. The investigated parameters are the position in the construction; the thickness, density, and dimensions of the construction parts; the contribution from the outer leave; the presence of doors and windows; the attenuation by internal partition walls; the contribution from building materials present in adjacent rooms; and the effect of non-equilibrium due to 222Rn exhalation. To verify the precision, the proposed method is applied to three Dutch reference dwellings, i.e., a row house, a coupled house, and a gallery apartment. The averaged difference with MCNP calculations is found to be 4%. PMID:18091149

de Jong, Peter; van Dijk, Willem

2008-01-01

323

Off-site air monitoring following methyl bromide chamber and building fumigations and evaluation of the ISCST air dispersion model  

Energy Technology Data Exchange (ETDEWEB)

The Department of Pesticide Regulation`s preliminary risk characterization of methyl bromide indicated an inadequate margin of safety for several exposure scenarios. Characterization of the air concentrations associated with common methyl bromide use patterns was necessary to determine specific scenarios that result in an unacceptable margin of safety. Field monitoring data were used in conjunction with the Industrial Source Complex, Short Tenn (ISCST) air dispersion model to characterize air concentrations associated with various types of methyl bromide applications. Chamber and building fumigations were monitored and modelled. For each fumigation the emission rates, chamber or building specifications and on-site meteorological data were input into the ISCST model. The model predicted concentrations were compared to measured air concentrations. The concentrations predicted by the ISCST model reflect both the pattern and magnitude of the measured concentrations. Required buffer zones were calculated using the ISCST output.

Barry, T.; Swgawa, R.; Wofford, P. [Cal EPA, Sacramento, CA (United States)] [and others

1995-12-31

324

Investigation of error propagation in the California Air Resources Board air quality model. Final report  

Energy Technology Data Exchange (ETDEWEB)

The study investigated the initiation and propagation of errors in the California Air Resources Board's airshed model (CalGrid) as a means of understanding the inherent precision and accuracy of photochemical model calculations. The most significant finding of the study is that the horizontal transport algorithm used by CalGrid is a source of significant error when concentration gradients are high (as is often observed in ozone episodes). This was tested in three ways: (1) the rotating puff test; (2) a rotating puff test with a parabolic tangential velocity profile; and (3) application of the Southern California Air Quality Study database. Each test suggested that the error in the horizontal advection algorithm is on the order of 20 to 40%. GalGrid's chemical mechanism solver was shown to have less error than the horizontal transport solver. The test showed no additional errors due to any mismatch of CalGrid's horizontal transport and chemical solution schemes. The study also introduced some new computational procedures that make use of stochastic finite elements for assessing error propagation. Using CalGrid's vertical transport code, it was found that vertical diffusivity errors and uncertainties were more significant than dry deposition and chemical conversion errors.

Odman, M.T.; Tatang, M.A.; Kumar, N.; McNair, L.A.; McRae, G.J.

1993-05-01

325

Mathematical modelling of air pollution in the Athens basin  

Energy Technology Data Exchange (ETDEWEB)

This paper presents research work concerning the mathematical modelling of air pollution in the Athens basin. A mathematical model based on aerodynamics and conservation equations together with turbulence modelling in body-fitted coordinates is used to provide the necessary input information to a similar but more detailed (i.e. small scale) model around Athens. Both models consist of solving the full Navier-Stokes equations and take into account the precise topography of the region. Different roughness heights are used for sea, coastal regions and land. The smaller scale model makes use of a two-equation turbulence model ({kappa}-{epsilon}) and the large scale model assumes a constant turbulence viscosity. The pollutant sources used in these models are based on actual emissions in the Athens area and are distributed in space. The results of this work appear promising and demonstrate the capability of the model as a tool for providing flow fields and pollution levels in complicated domains. (author) figs., tabs., refs.

Panagopoulos, J.; Markatos, N.C. [National Technical Univ. of Athens, Dep. of Chemical Engineering, Athens (Greece)

1991-12-31

326

Solar radiation modeling and measurements for renewable energy applications: data and model quality  

International Nuclear Information System (INIS)

Measurement and modeling of broadband and spectral terrestrial solar radiation is important for the evaluation and deployment of solar renewable energy systems. We discuss recent developments in the calibration of broadband solar radiometric instrumentation and improving broadband solar radiation measurement accuracy. An improved diffuse sky reference and radiometer calibration and characterization software for outdoor pyranometer calibrations are outlined. Several broadband solar radiation model approaches, including some developed at the National Renewable Energy Laboratory, for estimating direct beam, total hemispherical and diffuse sky radiation are briefly reviewed. The latter include the Bird clear sky model for global, direct beam, and diffuse terrestrial solar radiation; the Direct Insolation Simulation Code (DISC) for estimating direct beam radiation from global measurements; and the METSTAT (Meteorological and Statistical) and Climatological Solar Radiation (CSR) models that estimate solar radiation from meteorological data. We conclude that currently the best model uncertainties are representative of the uncertainty in measured data.

2005-01-01

327

Parameterization of solar radiation from model and observations  

Energy Technology Data Exchange (ETDEWEB)

The influence of the external and internal structure of clouds on the incoming solar radiation cannot yet be included in parameterizations used in numerical models. Based on numerical simulations, Schewski and Macke (2003) (Schewski-parameterization) have shown that a robust link exists between the domain averaged cloud and the domain averaged solar broadband radiation fluxes, despite the 3d nature of the cloud fields involved. The present work revisits this approach with observed cloud (cloud cover and liquid water path) and radiation (downwelling shortwave radiative flux) properties obtained from the Richard Assmann Observatory (RAO) of the German Weather Service in Lindenberg. Applying the original (model based) cloud-radiation parameterization by Schewski and Macke (2001) to observed domain averaged cloud fields yields an overall good correlation between observed and parameterized downwelling solar radiation fluxes. However, the parameterized fluxes strongly underestimate the observations. The Schewski parameterization has been modified by removing the bias and re-adjusting the parameterization coefficients to match the observed cloud and radiation correlation. Furthermore, the empirical parameterization by Zillman (1972) has been implemented for describing the clear conditions. Applying the new parameterization to an independent data set provides significant improvements. However, the accuracy remains in the order of previously used one- or two-parameter empirical cloud-radiation parameterizations. We conclude that cloud cover and liquid water path, i.e. those data that are available from large scale climate models, cannot be regarded as sufficient to describe the cloud radiative effect at the surface. (orig.)

Lengfeld, Katharina [IFM-GEOMAR Leibniz Inst. for Marine Science, Kiel (Germany); Meteologisches Inst., Univ. of Hamburg (Germany); Macke, Andreas [IFM-GEOMAR Leibniz Inst. for Marine Science, Kiel (Germany); Feister, Uwe; Gueldner, Juergen [Deutscher Wetterdienst, Lindenberg (Germany)

2010-02-15

328

Radiative Modeling of the Stratosphere of Jupiter  

Science.gov (United States)

Based on the recent 2D retrievals for temperature profiles and abundances of ethane (C2H6) and acetylene (C2H2) in the stratosphere of Jupiter from Cassini observations, the short wavelength heating and long wavelength cooling rates are calculated by correlated-k method. The Methane (CH4) k-distribution parameters from Irwin et al. (Icarus, 176, 255, 2006) and Karkoschka and Tomasko (Icarus, in press, 2009) and H2-H2 continuum absorption coefficients from Borysow et al. (A&A, 390, 779, 2002) are used for the heating rates calculations, covering all the CH4 bands from 0.5 µm to 5 µm. The heating rates due to stratospheric aerosol layers are also calculated based on the 2D aerosol distribution from Banfield et al. (Icarus, 134, 11, 1998). In the long wavelength region from 5 µm to 10 µm, the spectroscopic parameters are computed from the HITRAN 2008 database (Rothman et al., JQSRT, 110, 533, 2009), hydrogen-broadening coefficients for hydrocarbons (e.g., Varanasi et. al., JQSRT, 47, 263, 1992), and the recent H2-H2 and H2-He continuum absorption coefficients by Orton et al. (Icarus, 189, 544, 2007). A line-by-line radiative calculation is used to test the accuracy of our method. The quantitative modeling of the aforementioned species is important for constraining the 2D transport and chemistry of Jupiter. The major heat sources (short wavelength CH4 bands and aerosol absorption) and dominant coolants in the long wavelength spectral region for different pressure levels are studied.

Zhang, XI; West, R. A.; Orton, G. S.; Friedson, A. J.; Nixon, C. A.; Yung, Y. L.

2009-09-01

329

Air conditioner model study using Athens load control experiment data  

Energy Technology Data Exchange (ETDEWEB)

Development of more accurate models of power system load is important from the viewpoint of efficient operation of utility distribution systems. Appliance models that can be effectively used are needed by the utilities for implementing load control. A dynamic model of the response of a single air conditioner load to weather conditions was developed by Bargiotas and Birdwell and validated by the experimental results obtained in the Athens Automation and Control Experiment. The dynamic model is applied in this paper to predict duty cycle variations and the effect of load control intensities on indoor temperature. Actual data obtained from the Athens Automation and Control Experiment are used to compare the simulation results. 4 refs., 7 figs., 1 tab.

Reed, J.H.; Broadwater, R.P.; Chandrasekaran, A.; Shaalan, H.

1989-01-01

330

The effect of solar radiation on the thermal environment inside the air-conditioned automobile chamber  

Energy Technology Data Exchange (ETDEWEB)

The distribution of solar radiant energy inside the specific air-conditioned automobile chamber is studied on the basis of the unique wavelength spectrum. Some important optical parameters of the internal materials are mostly determined by experiments with monochromator, electron-multiplier phototube, etc. Some optical parameters of the thin transparent object are analyzed theoretically. Based on random model, Monte Carlo method is adopted to get the detailed distribution of solar radiant energy. The procedures of absorptivity, reflection and transmission of each ray are simulated and traced during the calculation. The universal software calculates two cases with different kind of glass. The relevant results show the importance of solar radiant energy on the thermal environment inside the air-conditioned automobile chamber. Furthermore, the necessity of shield quality of the automobile glass is also obvious. This study is also the basis of the following researches on fluid and temperature fields. The results are also useful for further thermal comfort design.

Tong, L.; Yang, K.; Chen, Z.

1999-07-01

331

Detection of changes induced in margarine exposed to air and to low level UV radiation: An intercomparison study  

Science.gov (United States)

Photoacoustic spectroscopy, photopyroelectric method, traditional visible and near infrared spectroscopies, fluorescence and the GC headspace analysis are used to observe changes induced in margarine samples exposed to air and/or to a low level UV radiation for periods ranging from 30 minutes to several days.

Gibkes, J.; Bicanic, D.; Cozijnsen, J.; Frankuizen, R.; Koehorst, R.; Dóka, O.; Jalink, H.

1999-03-01

332

A NEW COMBINED LOCAL AND NON-LOCAL PBL MODEL FOR METEOROLOGY AND AIR QUALITY MODELING  

Science.gov (United States)

A new version of the Asymmetric Convective Model (ACM) has been developed to describe sub-grid vertical turbulent transport in both meteorology models and air quality models. The new version (ACM2) combines the non-local convective mixing of the original ACM with local eddy diff...

333

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

334

An Analytic Radiative-Convective Model for Planetary Atmospheres  

CERN Multimedia

We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries, (2) worlds with some attenuation of sunli...

Robinson, Tyler D; 10.1088/0004-637X/757/1/104

2012-01-01

335

Radiative seesaw in left-right symmetric model  

International Nuclear Information System (INIS)

[en] There are some radiative origins for the neutrino masses in the conventional left-right symmetric models with the usual bidoublet and triplet Higgs scalars. These radiative contributions could dominate over the tree-level seesaw and could explain the observed neutrino masses.

2008-10-01

336

Radiative seesaw in left-right symmetric model  

CERN Multimedia

There are some radiative origins for the neutrino masses in the conventional left-right symmetric models with the usual bi-doublet and triplet Higgs scalars. These radiative contributions could dominate over the tree-level seesaw and could explain the observed neutrino masses.

Gu, Pei-Hong

2008-01-01

337

A photochemical box model for urban air quality study  

International Nuclear Information System (INIS)

The photochemical box model (PBM) is based on the principle of mass conservation. 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 has been further developed by considering the effect of urban heat islands to simulate the variation of the mixed layer height and incorporated in the PBM. The model predicted mixed layer height is a significant improvement over the characteristic mixed layer growth curve used in the original PBM by Schere and Demerjian. The gas phase chemical kinetic mechanism used in the Regional Acid Deposition Study II (RADM2) and Demerjian chemical mechanism 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 concentration using both chemical mechanisms are in very good agreement with observations. A radiative transfer model developed by Madronich has been incorporated in the PBM for the calculation of actinic flux and photolytic rate constants. Height averaged and radiation corrected photolytic rate constant are used for the photochemical reactions. The simulated pollutant concentrations for CO, NO, NO2 and Os are in very good agreement with observations. Sensitivities of model results to the variation of photolytic rate constants, boundary conditions, hydrocarbon speciation factors, and thermal rate constant have been tested

1991-01-01

338

Modeling hourly diffuse solar-radiation in the city of Sao Paulo using a neural-network technique  

International Nuclear Information System (INIS)

In this work, a perceptron neural-network technique is applied to estimate hourly values of the diffuse solar-radiation at the surface in Sao Paulo City, Brazil, using as input the global solar-radiation and other meteorological parameters measured from 1998 to 2001. The neural-network verification was performed using the hourly measurements of diffuse solar-radiation obtained during the year 2002. The neural network was developed based on both feature determination and pattern selection techniques. It was found that the inclusion of the atmospheric long-wave radiation as input improves the neural-network performance. On the other hand traditional meteorological parameters, like air temperature and atmospheric pressure, are not as important as long-wave radiation which acts as a surrogate for cloud-cover information on the regional scale. An objective evaluation has shown that the diffuse solar-radiation is better reproduced by neural network synthetic series than by a correlation model.

2004-01-01

339

Effect of radiation, hyperthermia and radio-hyperthermotherapy on experimental animal tumors; Comparison between in air and hypoxic condition  

Energy Technology Data Exchange (ETDEWEB)

Ehrlich ascites tumor cells were injected subcutaneously into the thigh of mouse. Tumors were treated by radiation, hyperthermia and radio-hyperthermotherapy. The effects of these treatments were compared between in air and hypoxic condition. The results were as follows. The effect of radiation was reduced by hypoxia, but reversely that of hyperthermia was increased by hypoxia. On radio-hyperthermotherapy, the effect was increased 1.5 times larger than that of radiation, in spite of adding short time hyperthermia which had small effect itself. Thermal enhancement ratio was 1.55 in air condition, and 1.74 in hypoxic condition. This result may suggest that many factors are related to thermal enhancement, for example, obstruction of sublethal damage repair and potentially lethal damage repair by hyperthermia, not only direct lethal damage by hyperthermia. It is problem that the effect of radiation is reduced by hypoxia, but hypoxic condition is favorable rather than air condition for hyperthermia. So combination of radiation and hyperthermia is thought to be valuable modality, especially for tumors in hypoxic condition. (author).

Yamane, Kanji (Kurume Univ., Fukuoka (Japan). School of Medicine)

1990-10-01

340

Quality criteria for air pollution models, standardisation and model development in the Netherlands  

International Nuclear Information System (INIS)

Based on standards of EPA and IEEE, quality criteria have been formulated which address the development of air pollution models, the transformation towards user-friendly software and ''after-sales'' service. A Dutch standard on the description of air pollution models is being finalized. The standard formulates minimal requirements on the theoretical and practical description of models. This paper provides a survey of the quality criteria and it summarizes the standard. Further, the current practice of model development at RIVM is discussed. (au) (24 refs.).

1992-01-01

 
 
 
 
341

The cloud-aerosol-radiation (CAR) ensemble modeling system  

Science.gov (United States)

A cloud-aerosol-radiation (CAR) ensemble modeling system has been developed to incorporate the largest choices of alternate parameterizations for cloud properties (cover, water, radius, optics, geometry), aerosol properties (type, profile, optics), radiation transfers (solar, infrared), and their interactions. These schemes form the most comprehensive collection currently available in the literature, including those used by the world's leading general circulation models (GCMs). CAR provides a unique framework to determine (via intercomparison across all schemes), reduce (via optimized ensemble simulations), and attribute specific key factors for (via physical process sensitivity analyses) the model discrepancies and uncertainties in representing greenhouse gas, aerosol, and cloud radiative forcing effects. This study presents a general description of the CAR system and illustrates its capabilities for climate modeling applications, especially in the context of estimating climate sensitivity and uncertainty range caused by cloud-aerosol-radiation interactions. For demonstration purposes, the evaluation is based on several CAR standalone and coupled climate model experiments, each comparing a limited subset of the full system ensemble with up to 896 members. It is shown that the quantification of radiative forcings and climate impacts strongly depends on the choices of the cloud, aerosol, and radiation schemes. The prevailing schemes used in current GCMs are likely insufficient in variety and physically biased in a significant way. There exists large room for improvement by optimally combining radiation transfer with cloud property schemes.

Liang, X.-Z.; Zhang, F.

2013-08-01

342

Preliminary results of a three-dimensional radiative transfer model  

Energy Technology Data Exchange (ETDEWEB)

Clouds act as the primary modulator of the Earth`s radiation at the top of the atmosphere, within the atmospheric column, and at the Earth`s surface. They interact with both shortwave and longwave radiation, but it is primarily in the case of shortwave where most of the uncertainty lies because of the difficulties in treating scattered solar radiation. To understand cloud-radiative interactions, radiative transfer models portray clouds as plane-parallel homogeneous entities to ease the computational physics. Unfortunately, clouds are far from being homogeneous, and large differences between measurement and theory point to a stronger need to understand and model cloud macrophysical properties. In an attempt to better comprehend the role of cloud morphology on the 3-dimensional radiation field, a Monte Carlo model has been developed. This model can simulate broadband shortwave radiation fluxes while incorporating all of the major atmospheric constituents. The model is used to investigate the cloud absorption anomaly where cloud absorption measurements exceed theoretical estimates and to examine the efficacy of ERBE measurements and cloud field experiments. 3 figs.

O`Hirok, W. [Univ. of California, Santa Barbara, CA (United States)

1995-09-01

343

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

344

Gaseous tracer model for air pollution from residential wood burning  

Energy Technology Data Exchange (ETDEWEB)

A novel method is proposed whereby one may determine the contributions of wood burning, and other anthropogenic sources, to urban air pollution. This gaseous tracer model (GTM) relates the concentrations of methyl chloride (CH3Cl) in polluted environments to the mass of fine particles emitted from wood burning. As a distinct advantage over existing methods this model can provide almost real-time assessment of the contribution of anthropogenic sources to urban pollution. When the model was applied to data obtained over the winter of 1981 at various surburban locations near Portland, OR, it showed that during peak wood-burning periods of the evening when wood smoke is evident, about 130 microgram/cu m of fine particles may be contributed by this source. The effect of wood burning is reduced when averaged over 24 h, and the results agree with past studies that used different analytical methods. 23 references.

Khalil, M.A.K.; Edgerton, S.A.; Rasmussen, R.A.

1983-09-01

345

Troposphere-stratosphere radiation field at twilight: a spherical model  

Energy Technology Data Exchange (ETDEWEB)

Time-dependent calculations of trace constituent distributions require as input the dissociating radiation field as a function of altitude and solar zenith angle. An isotropic, spherical, multiple scattering model of the radiation field has been developed to determine the radiation field at twilight. Comparison of the spherical model with a plane parallel model at twilight shows that: (1) for solar zenith angles less than 92/sup 0/, plane parallel solutions for the source function are suitable if the initial deposition of solar energy is calculated for a spherical atmosphere; (2) for solar zenith angles greater than 92/sup 0/, the plane parallel radiation field can be several orders of magnitude smaller than that calculated with the spherical model; (3) at altitudes above 40 km and at all solar zenith angles, the spherical model predicts 10-20% less radiation than the radiation field calculated with the plane parallel model. Calculations of the rate of photodissociation of NO/sub 2/ in the troposphere and stratosphere show that the spherical model yields significantly higher values at solar zenith angles greater than 92/sup 0/.

Anderson, D.E. Jr. (Hulburt (E.O.) Center for Space Research, Washington, DC (USA))

1983-12-01

346

Air dispersion modeling for a class III PSD reclassification study  

Energy Technology Data Exchange (ETDEWEB)

The Illinois Environmental Protection Agency has recently completed a Prevention of Significant Deterioration (PSD) study to serve as a basis for the reclassification to Class III of an Illinois three country region east of St. Louis, Missouri. The reclassification, which is the first attempt for a Class III status in the United States, would apply only to sulfur dioxide since the area is mostly nonattainment with respect to ambient particulate concentrations. To assist in the assessment of environmental and economic effects of reclassification, short and long term air dispersion modeling was applied. Several major industrial sources emitting sulfur dioxide were modeled using five years of meterological data from nearby Lambert Airport and an upper air sounding station in Salem, Illionis. Analysis of the data suggests that reclassification would allow some sources to emit more than they could under Class II. Also, reclassification would allow more clustering of new sources. Most of the ambient sulfur dioxide attainment townships located in the Mississippi River flood plain, however, are potentially nonattainment according to recent modeling and monitoring data. This circumstance could negate most of the benefits derived from a Class III status.

Crenshaw, J.; Thornton, C.

1982-01-01

347

Atomic physics and radiation transport models for ICF targets  

International Nuclear Information System (INIS)

The authors present the basis of a calculational model capable of analyzing more deeply high energy gain targets. It includes two main features: improved atomic physics and radiation transport capability.

1986-07-04

348

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

349

Mathematical model predicts performance of pipeline drying with air  

Energy Technology Data Exchange (ETDEWEB)

The presence of water before starting normal pipeline operation usually results from the hydrostatic test of the lines. Most of the water used for the test can be removed by having sequences of pigs with different characteristics run through the lines according to appropriate procedures. After this operation, usually a small amount of water wets the pipe internal wall. This residual water may be eliminated by some alternative processes. This article examines a drying process based on the flow of dry air. A mathematical model of this process is presented together with the results of its use for a project.

Bettarra, V.; Bilardo, U.; Selandari, S.

1984-06-11

350

Radiation passbook and training model for outside workers in Spain  

International Nuclear Information System (INIS)

European Directive 90/641/Euratom established the general framework for operational protection of outside workers exposed to the risk of ionising radiation during their activities in controlled areas. In Spain this Directive has been transposed through Royal Decree 413/1997, which established specific responsibilities regarding Radiation Passbook and the training in radiation protection of outside workers. The Spanish radiation passbook was introduced in 1990 and since this time, Nuclear Safety Council (CSN), as the regulatory authority has required that all outside workers entering controlled areas should have radiation passbooks. Recently, CSN has implemented improvements in the Spanish radiation passbooks taking into account the previous experience and the Directive 96/29/Euratom. With regard to training in radiation protection of outside workers, in 1998 the CSN and the Association of the electricity utilities (UNESA) initiated joint efforts to define a new radiation protection training model for Spanish outside workers. This model should involve both the outside undertaking and the nuclear power plants. Several options already implemented in other European countries were studied and as result a model based on the following criteria was developed: - An initial training course which is responsibility of the outside undertaking. - A specific course which will be responsibility of the operators of the controlled area in which outside workers perform the activities. (authors)

2003-01-01

351

Quantifying urban street configuration for improvements in air pollution models  

Science.gov (United States)

In many built-up urban areas, tall buildings along narrow streets obstruct the free flow of air, resulting in higher pollution levels. Input data to account for street configuration in models are difficult to obtain for large numbers of streets. We describe an approach to calculate indicators of this "urban canyon effect" using 3-dimensional building data and evaluated whether these indicators improved spatially resolved land use regression (LUR) models.Concentrations of NO2 and NOx were available from 132 sites in the Netherlands. We calculated four indicators for canyon effects at each site: (1) the maximum aspect ratio (building height/width of the street) between buildings on opposite sides of the street, (2) the mean building angle, which is the angle between the horizontal street level and the line of sight to the top of surrounding buildings, (3) median building angle and (4) "SkyView Factor" (SVF), a measure of the total fraction of visible sky. Basic LUR models were computed for both pollutants using common predictors such as household density, land-use and nearby traffic intensity. We added each of the four canyon indicators to the basic LUR models and evaluated whether they improved the model.The calculated aspect ratio agreed well (R2 = 0.49) with aspect ratios calculated from field observations. Explained variance (R2) of the basic LUR models without canyon indicators was 80% for NO2 and 76% for NOx, and increased to 82% and 78% respectively if SVF was included. Despite this small increase in R2, contrasts in SVF (10th-90th percentile) resulted in substantial concentration differences of 5.56 ?g m-3 in NO2 and 10.9 ?g m-3 in NOx.We demonstrated a GIS based approach to quantify the obstruction of free air flow by buildings, applicable for large numbers of streets. Canyon indicators could be valuable to consider in air pollution models, especially in areas with low- and high-rise canyons.

Eeftens, Marloes; Beekhuizen, Johan; Beelen, Rob; Wang, Meng; Vermeulen, Roel; Brunekreef, Bert; Huss, Anke; Hoek, Gerard

2013-06-01

352

[Treatment of cloud radiative effects in general circulation models  

International Nuclear Information System (INIS)

This is a renewal proposal for an on-going project of the Department of Energy (DOE)/Atmospheric Radiation Measurement (ARM) Program. The objective of the ARM Program is to improve the treatment of radiation-cloud in GCMs so that reliable predictions of the timing and magnitude of greenhouse gas-induced global warming and regional responses can be made. The ARM Program supports two research areas: (I) The modeling and analysis of data related to the parameterization of clouds and radiation in general circulation models (GCMs); and (II) the development of advanced instrumentation for both mapping the three-dimensional structure of the atmosphere and high accuracy/precision radiometric observations. The present project conducts research in area (I) and focuses on GCM treatment of cloud life cycle, optical properties, and vertical overlapping. The project has two tasks: (1) Development and Refinement of GCM Radiation-Cloud Treatment Using ARM Data; and (2) Validation of GCM Radiation-Cloud Treatment

1993-01-01

353

[Treatment of cloud radiative effects in general circulation models  

Energy Technology Data Exchange (ETDEWEB)

This is a renewal proposal for an on-going project of the Department of Energy (DOE)/Atmospheric Radiation Measurement (ARM) Program. The objective of the ARM Program is to improve the treatment of radiation-cloud in GCMs so that reliable predictions of the timing and magnitude of greenhouse gas-induced global warming and regional responses can be made. The ARM Program supports two research areas: (I) The modeling and analysis of data related to the parameterization of clouds and radiation in general circulation models (GCMs); and (II) the development of advanced instrumentation for both mapping the three-dimensional structure of the atmosphere and high accuracy/precision radiometric observations. The present project conducts research in area (I) and focuses on GCM treatment of cloud life cycle, optical properties, and vertical overlapping. The project has two tasks: (1) Development and Refinement of GCM Radiation-Cloud Treatment Using ARM Data; and (2) Validation of GCM Radiation-Cloud Treatment.

Wang, W.C.

1993-11-01

354

Radiative lepton flavour violation in SUSY GUT models  

Energy Technology Data Exchange (ETDEWEB)

The small flavour mixing in the quark sector can be generated radiatively from SUSY-breaking terms in the MSSM. However,it seems difficult to generate the large neutrino mixing radiatively. Embedding the MSSM into a left-right symmetric model, which realizes the seesaw formula for the light neutrino masses, we constrain the trilinear terms in the SUSY breaking sector. In this class of models we get an appealing correlation between LR breaking scale and soft SUSY breaking parameters.

Bobrowski, Markus; Hollik, Wolfgang G.; Nierste, Ulrich [Institut fuer Theoretische Teilchenphysik, KIT, Karlsruhe (Germany)

2012-07-01

355

Parameterization of clouds and radiation in climate models  

Energy Technology Data Exchange (ETDEWEB)

Clouds are a very important, yet poorly modeled element in the climate system. There are many potential cloud feedbacks, including those related to cloud cover, height, water content, phase change, and droplet concentration and size distribution. As a prerequisite to studying the cloud feedback issue, this research reports on the simulation and validation of cloud radiative forcing under present climate conditions using the ECHAM general circulation model and ERBE top-of-atmosphere radiative fluxes.

Roeckner, E. [Max Planck Institute for Meterology, Hamburg (Germany)

1995-09-01

356

Air  

International Nuclear Information System (INIS)

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

2001-01-01

357

Solar Radiation Estimated Through Mesoscale Atmospheric Modeling over Northeast Brazil  

Science.gov (United States)

The use of renewable energy sources, like solar, wind and biomass is rapidly increasing in recent years, with solar radiation as a particularly abundant energy source over Northeast Brazil. A proper quantitative knowledge of the incoming solar radiation is of great importance for energy planning in Brazil, serving as basis for developing future projects of photovoltaic power plants and solar energy exploitation. This work presents a methodology for mapping the incoming solar radiation at ground level for Northeast Brazil, using a mesoscale atmospheric model (Regional Atmospheric Modeling System-RAMS), calibrated and validated using data from the network of automatic surface stations from the State Foundation for Meteorology and Water Resources from Ceará (Fundaça~o Cearense de Meteorologia e Recursos Hídricos- FUNCEME). The results showed that the model exhibits systematic errors, overestimating surface radiation, but that, after the proper statistical corrections, using a relationship between the model-predicted cloud fraction, the ground-level observed solar radiation and the incoming solar radiation estimated at the top of the atmosphere, a correlation of 0.92 with a confidence interval of 13.5 W/m2 is found for monthly data. Using this methodology, we found an estimate for annual average incoming solar radiation over Ceará of 215 W/m2 (maximum in October: 260 W/m2).

de Menezes Neto, Otacilio Leandro; Costa, Alexandre Araújo; Ramalho, Fernando Pinto; de Maria, Paulo Henrique Santiago

2009-03-01

358

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

359

A space radiation shielding model of the Martian radiation environment experiment (MARIE)  

International Nuclear Information System (INIS)

The 2001 Mars Odyssey spacecraft was launched towards Mars on April 7, 2001. On board the spacecraft is the Martian radiation environment experiment (MARIE), which is designed to measure the background radiation environment due to galactic cosmic rays (GCR) and solar protons in the 20 500 MeV/n energy range. We present an approach for developing a space radiation-shielding model of the spacecraft that includes the MARIE instrument in the current mapping phase orientation. A discussion is presented describing the development and methodology used to construct the shielding model. For a given GCR model environment, using the current MARIE shielding model and the high-energy particle transport codes, dose rate values are compared with MARIE measurements during the early mapping phase in Mars orbit. The results show good agreement between the model calculations and the MARIE measurements as presented for the March 2002 dataset.

2004-12-01

360

The all-sky meteorological radiation model: proposed improvements  

International Nuclear Information System (INIS)

The all-sky meteorological radiation model is a broadband solar-radiation estimation model that uses synoptic and sunshine information. The original model due to Muneer-Gul-Kambezidis was improved using regressions based on the sunshine fraction to increase the accuracy of the estimation of diffuse horizontal irradiation, thus achieving an accuracy increase for the estimation of the global horizontal irradiation. The improved model was validated using data from ten worldwide sites and using three statistical indicators:-coefficient of determination between computed and measured global irradiation data and the relevant, mean bias error and the root mean square error of the computed global irradiation. The performance of the new model was improved when compared to that of the original model. The new regression coefficients were found to be more accurate in estimating global horizontal radiation for both fine and coarse datasets.

2006-01-01

 
 
 
 
361

Air pollution modeling for an industrial complex and model performance evaluation  

International Nuclear Information System (INIS)

Jamshedpur, the steel city of India situated in the eastern part of India is affected by increasing air pollution levels as a result of concentrated industrial activities. The impact of NOx emissions resulting from various air pollution sources, viz. industries, vehicles and domestic, was estimated using Industrial Source Complex Short-Term gaussian dispersion model. The contribution of NOx concentration from industrial, vehicular and domestic sources was found to be 53, 40 and 7%. Further statistical analysis was carried out to evaluate the model performance by comparing measured and predicted NOx concentrations. The model performance was found good with an accuracy of about 68%. (Author)

2001-01-01

362

DEVELOPMENT OF MESOSCALE AIR QUALITY SIMULATION MODELS. VOLUME 6. USER'S GUIDE TO MESOPAC (MESOSCALE METEOROLOGY PACKAGE)  

Science.gov (United States)

MESOPAC is a mesoscale meteorological preprocessor program; it is designed to provide meteorological data to regional-scale air quality simulation models. Radiosonde data routinely available from National Weather Service (NWS) radiosonde ('upper air') and surface stations are use...

363

Wind shadow model for air infiltration sheltering by upwind obstacles  

Energy Technology Data Exchange (ETDEWEB)

A wind shadow model has been developed to calculate the wind sheltering effects of upwind obstacles for air infiltration calculations. This effect must be determined for infiltration calculations because, in almost all situations, only the unobstructed mean wind speed is known for a building site. This model has adapted the theoretical calculation procedures developed for far wake centerline velocity deficit calculations to near field flows, where shelter has a significant effect. The model uses the concept of a wind shadow projected downstream by upwind buildings to determine the effect of wake velocity reduction on building surfaces. The turbulent nature of the wake is accounted for by flapping the wake over a range of wind directions. The effectiveness of this model in accounting for sheltering effects in infiltration calculations has been examined by comparing infiltration model predictions including the wind shadow model to measured data from a row of test houses. The measured data covered a wide range of wind speeds, wind directions and leakage distributions by using over 5000 hours of infiltration measurements from five houses.

Walker, I.S. [Lawrence Berkeley National Lab., CA (United States); Wilson, D.J.; Forest, T.W. [Univ. of Alberta (Canada). Dept. of Mechanical Engineering

1997-12-31

364

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)

2003-01-01

365

Conjugate turbulent natural convection with surface radiation in air filled rectangular enclosures  

Energy Technology Data Exchange (ETDEWEB)

Conjugate turbulent natural convection and surface radiation in rectangular enclosures heated from below and cooled from other walls, typically encountered in Liquid Metal Fast Breeder Reactor (LMFBR) subsystems, have been investigated by a finite volume method for various aspect ratios. The formulation comprises the standard two equation k-{epsilon} turbulence model with physical boundary conditions (no wall functions), along with the Boussinesq approximation, for the flow and heat transfer. As far as radiation is concerned, the radiosity - irradiation formulation for a transparent fluid of Prandtl number 0.7 has been employed. The conjugate coupling on the walls has been handled by using a fin type formulation. The Rayleigh number based on the width of the enclosure is varied from 10{sup 8} to 10{sup 12} and the aspect ratio is varied from 0.5 to 2.0. Detailed results including stream lines, temperature profiles, and convective, radiative and overall Nusselt numbers are presented. A correlation for the mean convection Nusselt number in terms of Rayleigh number and aspect ratio is proposed for design purposes. The influence of the wall emissivity and the external heat transfer coefficient on the heat transfer from the enclosure has also been investigated. (author)

Sharma, Anil Kumar; Velusamy, K. [Indira Gandhi Center for Atomic Research, Kalpakkam (India). Safety Engineering Division, Safety Group, Department of Atomic Energy; Balaji, C.; Venkateshan, S.P. [Indian Institute of Technology Madras, Chennai (India). Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering

2007-02-15

366

Radiation transport phenomena and modeling - part A: Codes  

International Nuclear Information System (INIS)

[en] The need to understand how particle radiation (high-energy photons and electrons) from a variety of sources affects materials and electronics has motivated the development of sophisticated computer codes that describe how radiation with energies from 1.0 keV to 100.0 GeV propagates through matter. Predicting radiation transport is the necessary first step in predicting radiation effects. The radiation transport codes that are described here are general-purpose codes capable of analyzing a variety of radiation environments including those produced by nuclear weapons (x-rays, gamma rays, and neutrons), by sources in space (electrons and ions) and by accelerators (x-rays, gamma rays, and electrons). Applications of these codes include the study of radiation effects on electronics, nuclear medicine (imaging and cancer treatment), and industrial processes (food disinfestation, waste sterilization, manufacturing.) The primary focus will be on coupled electron-photon transport codes, with some brief discussion of proton transport. These codes model a radiation cascade in which electrons produce photons and vice versa. This coupling between particles of different types is important for radiation effects. For instance, in an x-ray environment, electrons are produced that drive the response in electronics. In an electron environment, dose due to bremsstrahlung photons can be significant once the source electrons have been stopped

1997-01-01

367

Program description of FIBRAM (Fiber Optic Radiation Attenuation Model): a radiation attenuation model for optical fibers  

International Nuclear Information System (INIS)

[en] The report describes a fiber-optics system model and its computer implementation. This implementation can calculate the bit error ratio (BER) versus time for optical fibers that have been exposed to gamma radiation. The program is designed so that the user may arbitrarily change any or all of the system input variables and produce separate outputs. The primary output of the program is a table of the BER as a function of time. This table may be stored on magnetic media and later incorporated into computer graphic programs. The program was written in FORTRAN 77 for the IBM PC/AT/XT computers. Flow charts and program listings are included in the report

1987-01-01

368

Evolution of perturbations in 3D air quality models  

Directory of Open Access Journals (Sweden)

Full Text Available The deterministic approach of sensitivity analysis is applied on the solution vector of an Air Quality Model. In particular, the photochemical CAMx code is augmented with derivatives utilising the automatic differentiation software ADIFOR. The enhanced with derivatives version of the model is then adopted in a study of the effect of perturbations at the boundary conditions on the predicted ozone concentrations. The calculated derivative matrix provides valuable information e.g., on the ordering of the infl uential factors or the localisation of highly affected regions. Two fundamentally different domains of the Auto-Oil II programme were used as test cases for the simulations, namely Athens and Milan. The results suggest that ozone concentration be highly affected by its own boundary conditions and subsequently, with an order of magnitude less, by the boundary conditions of NOX and VOC.

I. Kioutsioukis; C. Zerefos; D. Melas; I. Ziomas

2003-01-01

369

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

370

Performance of the meteorological radiation model during the solar eclipse of 29 March 2006  

Directory of Open Access Journals (Sweden)

Full Text Available Various solar broadband models have been developed in the last half of the 20th century. The driving demand has been the estimation of available solar energy at different locations on earth for various applications. The motivation for such developments, though, has been the ample lack of solar radiation measurements at global scale. Therefore, the main goal of such codes was to generate artificial solar radiation series or calculate the availability of solar energy at a place. One of the broadband models to be developed in the late 80's was the Meteorological Radiation Model (MRM). The main advantage of MRM over other similar models was its simplicity in acquiring and using the necessary input data, i.e., air temperature, relative humidity, barometric pressure and sunshine duration from any of the many meteorological stations. The present study describes briefly the various steps (versions) of MRM and in greater detail the latest version 5. To show the flexibility and great performance of the MRM, a harsh test of the code under the (almost total) solar eclipse conditions of 29 March 2006 over Athens was performed and comparison of its results with real measurements was made. From this hard comparison it is shown that the MRM can simulate solar radiation during a solar eclipse event as effectively as on a typical day. The value of this comparison is further enhanced if it said that the sky was cloudy almost all the duration of the solar eclipse event.

B. E. Psiloglou; H. D. Kambezidis

2007-01-01

371

An efficient tabulated collisional radiative equilibrium radiation transport model suitable for multidimensional hydrodynamics calculations  

International Nuclear Information System (INIS)

A computationally efficient method for transporting radiation in multidimensional plasmas has been developed and evaluated. The basis of this method is a uniform plasma approximation that allows one to utilize existing escape probability techniques that are successfully used in one-dimensional (1D) calculations to approximately solve the multidimensional radiation transport problem. This method is superior to diffusion methods because (1) the probability of escape technique insures that the plasma goes to the correct optically thin and thick limits, (2) the effects of line absorption due to photoexcitations are modeled, and (3) this method uses source functions that are based on a self-consistent nonlocal thermodynamic equilibrium calculation, not an ad hoc assumption that the source functions are Planckian. This method is highly efficient because equation of state information from 1D calculations is tabulated as a function of plasma internal energy, ion density, and the line probability of escape from a uniform plasma, and then used in multidimensional calculations. Given the internal energy and ion density, and by calculating the line probability of escape from a zone of the multidimensional plasma, the equation of state, including emissivities and absorption coefficients, of the zone is determined from the table. Total radiative power, K-shell radiative power, total radiative yield, K-shell radiative yield, and plasma density and temperature profiles obtained from 1D Z-pinch calculations employing this method are in good agreement with the same powers, yields, and profiles calculated using a full radiation transport model. This method has been implemented in the 2D plasma radiating imploding source model code [F. L. Cochran et al., Phys. Plasmas 2, 2765 (1995)] to determine the influence of radiation transport in argon Z-pinch experiments performed on the Z machine [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories.

2001-01-01

372

Simulation and modeling of solar radiation in Saudi Arabia  

Energy Technology Data Exchange (ETDEWEB)

A mathematical model is used to generate the hourly data for the total solar radiation on a horizontal surface. The generated data are based on the hourly recorded visibility data for 20 years (1970-1989). The model year technique was then applied to model the 20 years of hourly data of solar radiation into one statistically representative year. A model year of hourly data was then generated for the beam and diffuse components of solar radiation on a horizontal surface. Similarly, a model year of hourly data was also generated for the total solar radiation on tilted surfaces with different orientations with its beam, diffuse and reflected components. A simple methodology is proposed for calculating the solar radiation on vertical surfaces, based on a solar impact factor (SIF). Monthly means and daily totals of hourly sums for each month of the year are discussed. The hourly data of solar radiation for a typical day for each month of the year are presented. The data were generated for the four climatic zones of Saudi Arabia, the hot-dry (Riyadh), the warm-humid (Jeddah), the maritime inland desert climate (Dhahran) and the upland climate zone (Taif). The accuracy of the results is discussed and found to be above 90% representative. (author)

Zuhairy, A.A.; Sayigh, A.A.M. [Reading Univ. (United Kingdom). Dept. of Engineering

1995-04-01

373

Atmospheric Boundary Layer Modeling for Combined Meteorology and Air Quality Systems  

Science.gov (United States)

Atmospheric Eulerian grid models for mesoscale and larger applications require sub-grid models for turbulent vertical exchange processes, particularly within the Planetary Boundary Layer (PSL). In combined meteorology and air quality modeling systems consistent PSL modeling of wi...

374

Solar radiation and shadow modelling with adaptive triangular meshes  

Energy Technology Data Exchange (ETDEWEB)

In this work, we propose a numerical model for generating solar radiation maps with the use of 2-D adaptive meshes of triangles. These triangulations are constructed by using a refinement/derefinement procedure in accordance with the variations of terrain surface orography and albedo. This discretization has the advantage of defining the terrain characteristics with a minimum number of points, which reduces the computational cost for a given accuracy. Moreover, the model takes into account the effect of shadows for each time step, which are detected by analysing the crossing of the trajectory of the shaft of light with the triangles of the mesh. Thus, the solar radiation is first computed for clear-sky considering the different components of radiation, that is, beam, diffuse and reflected radiations. From the results of clear-sky radiation, the real-sky radiation is computed daily in terms of the clear-sky index. The maps of clear-sky index are obtained from a spatial interpolation of observational data that are available for each day at several points of the zone under consideration. Finally, the solar radiation maps of a month are calculated from the daily results. We illustrate the performance of the model with a numerical experiment related to an episode on the island of Gran Canaria. (author)

Montero, G.; Escobar, J.M.; Rodriguez, E.; Montenegro, R. [University Institute for Intelligent Systems and Numerical Applications in Engineering, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria (Spain)

2009-07-15

375

Laser-induced fluorescence measurements and modeling of nitric oxide in methane-air and ethane-air counterflow diffusion flames  

Energy Technology Data Exchange (ETDEWEB)

Quantitative laser-induced fluorescence (LIF) measurements of nitric oxide concentrations[NO] have been obtained along the centerline in atmospheric pressure methane-air and ethane-air counterflow diffusion flames. These flames are highly diluted to avoid both soot formation and the influence of radiative heat losses on NO formation, thereby ensuring NO production mostly via the prompt mechanism. Linear LIF measurements of [NO] are corrected for variations in the electronic quenching rate coefficient by using major species profiles generated by an opposed-flow flame code and quenching cross-sections for NO available from the literature. Temperature measurements are also made in the methane-air counterflow diffusion flames by using thin SiC filament pyrometry. The excellent agreement between temperature measurements and model predictions verifies the efficacy of a new calibration method developed for thin filament pyrometry. Predictions using the GRI mechanism consistently underpredict peak [NO] in all flames. This result indicates a need for refinement of both the prompt-NO and CH kinetics, especially the rate coefficient for the prompt-NO initiation reaction. A modified rate coefficient proposed for the prompt-NO initiation reaction significantly improves agreement between modeling and measurements in both the methane-air and ethane-air counterflow diffusion flames. The remaining discrepancy in some flames can be attributed to a lack of refinement in the CH chemistry. Overall, the modified rate coefficient proposed here seems to be a good choice over a wide range of strain rates for both methane and ethane fuels.

Ravikrishna, R.V.; Laurendeau, N.M.

2000-02-01

376

A study on radiation dose analysis model  

International Nuclear Information System (INIS)

CRONIC and GASPAR Codes, which are based on USNRC Regulatory Guide 1.109, ''Calculation of annual doses to man from routine releases of reactor effluents for the purpose of evaluatino. compliance with 10 CFR Part 50, Appendix I'', are tested and now ready for immediate use. CRONIC Code is a program which will compute the external whole body dose from the radiation emitted directly by radioactive clouds. Gaseous reactor effluents will reach finally to man through environmental media of surrounding area about nuclear power plant site. GASPAR Code is a program to estimate the individual and population doses from all pathways of gaseous radioactive effluents, and the allowable emission limit to meet the environmental radiation standard will be determined for specific nuclides. In 1982, these codes will be applied to the environmental impact assessment and safety analysis for the Kori site. (Author)

1982-01-01

377

Measurements of external radiation and radioactivity in soil and air in Novozybkov, USSR  

Energy Technology Data Exchange (ETDEWEB)

At the invitation of the International Atomic Energy Agency, a five-member team from the Environmental Measurements Laboratory performed an intensive survey of the town of Novozybkov, USSR to corroborate the levels of environmental contamination as part of an overall assessment of the radiological consequences of the Chernobyl accident. Novozybkov was selected as a principal study site within the Russian Federation because it was believed to be in an area that received relatively heavy fallout. The field work was conducted over a 2-week period during the summer of 1990. Over 1000 measurements of external radiation were performed using pressurized ionization chambers. The absorbed dose rate in air (nGy h{sup {minus}}1) outdoors from all sources (fallout plus natural background, including cosmic) averaged 821 for undistributed sites, 440 for gardens and other distributed areas, and 230 for paved surfaces. The indoor values averaged 159 for wooden houses, 121 for masonry houses, 93 for public buildings and workplaces, and 83 for apartment buildings.

Miller, K.M.; Klusek, C.S.; Hutter, A.R.; Monetti, M.; Davis, H.A.

1991-12-01

378

Coherent Radiation from Extensive Air Showers in the Ultra-High Frequency Band  

CERN Document Server

Using detailed Monte Carlo simulations we have characterized the features of the radio emission of inclined air showers in the Ultra-High Frequency band (300 MHz - 3 GHz). The Fourier-spectrum of the radiation is shown to have a sizable intensity well into the GHz frequency range. The emission is mainly due to transverse currents induced by the geomagnetic field and to the excess charge produced by the Askaryan effect. At these frequencies only a significantly reduced volume of the shower around the axis contributes coherently to the signal observed on the ground. The size of the coherently emitting volume depends on frequency, shower geometry and observer position, and is interpreted in terms of the relative time delays. At ground level, the maximum emission at high frequencies is concentrated in an elliptical ring-like region around the intersection of a Cherenkov cone with its vertex at shower maximum and the ground. The frequency spectrum of inclined showers when observed at positions that view shower max...

Alvarez-Muñiz, Jaime; Romero-Wolf, Andrés; Tueros, Matías; Zas, Enrique

2012-01-01

379

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

International Nuclear Information System (INIS)

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

2009-01-01

380

Thermal performance of flat plate solar collectors using an air gap and/or radiation shields as rear insulation  

Energy Technology Data Exchange (ETDEWEB)

Several techniques have been developed over the years to minimize the front/top losses from the flat plate solar collector. The rear/bottom losses are normally catered for by providing a sufficient thickness of insulating material thus reducing these losses to one predominantly of conduction. In this paper it is shown that, for small slopes appropriate to a typical tropical latitude, the rear insulation can be dispensed with in favour of an air gap or preferably an air gap fitted with a radiation shield.

Satcunanathan, S.; Gandhidasan, P.

1980-12-01

 
 
 
 
381

Impact of photochemical modeling and air quality regulations on industrial development - A case study  

Energy Technology Data Exchange (ETDEWEB)

A case study of the impact of photochemical modeling and air quality regulations on industrial development is summarized. Topics discussed include: the industrial boiler owners challenge, overview of photochemical modeling efforts, issues associated with ozone nonattainment evaluations, impact of photochemical modeling on air rules, federal provisions for ozone regulatory changes, ozone control mechanisms, cogeneration project, significant permitting issues, air permitting requirements for NOx and VOC`s, equipment selection, and potential impact of photochemical modeling on future industrial operations.

Burdorf, B. [Trinity Consultants Incorporated, Dallas, TX (United States); Modi, K. [Trinity Consultants Inc., Phildelphia, PA (United States)

1996-11-01

382

Czech air quality monitoring and receptor modeling study  

International Nuclear Information System (INIS)

An ongoing air quality monitoring program in the Czech Republic has provided nearly continuous data for the concentrations of aerosols and gas-phase pollutants since its inception in February 1992. In addition to PM-2.5 concentrations, the concentrations of sulfate, organic carbon, elemental carbon, trace elements (Al-Pb), and polynuclear aromatic hydrocarbons (PAHs) were also measured. Fine particulate matter (PM-2.5) was composed mainly of organic carbon and sulfate with smaller amounts of trace metals. Coarse particle mass concentrations were typically between 10 and 30% of PM-2.5 concentrations. The chemical composition of emissions from power plants, residential space heating, local factories, and motor vehicles was also characterized. The ambient monitoring and source characterization data were then used in receptor modeling calculations, the results of which indicate that residential space heating and power plant emissions accounted for most of fine particle mass concentrations observed during winter air pollution episodes. Motor vehicles, incinerators, and windblown dust contributed to the balance of the fine particle mass. Peak 24-h average TSP and SO2 concentrations (1100 and 800?g/m3, respectively) obtained at the main monitoring site at Teplice in northern Bohemia during a severe air pollution episode in 1993 were within a factor of 2 of smoke and SO2 concentrations (1800 and 1600 ?g/m3) measured in London during the smog episode of December 5-9, 1952. That pollution episode was thought to have contributed to a substantial increase in mortality. 24 refs., 8 figs., 8 tabs

1998-04-01

383

Air kerma to Hp(3) conversion coefficients for a new cylinder phantom for photon reference radiation qualities.  

UK PubMed Central (United Kingdom)

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no