WorldWideScience

Sample records for variable 6307a emission

  1. Emission-Line Region Variability

    Science.gov (United States)

    Peterson, Bradley M.

    We propose to obtain simultaneous optical and ultraviolet observations of the rapidly varying active galaxies Akn 120 and 3C 120. Both these sources are distinguished by short-time scale variations in their continuum and broadline fluxes, and we intend to exploit this property to determine fundamental characteristics of the emission-line gas. Akn 120 has been studied extensively by the Ohio State group, and is one of the few active galaxies for which a reliable upper limit for the separation between the continuum source and the emission-line clouds has been established from reverberation measurements. The important goals of the proposed project are (1) to provide a suitable database of optical and ultraviolet broad-line flux measurements obtained during different continuum states and (2) to compare the temporal behavior of optical and ultraviolet emission lines. In particular, we wish to determine whether or not C III] A1909 varies on the same time scale as the Balmer lines and how much of the flux in this feature can actually be ascribed to broad-line emission from C^+2. These data will enable us to make a differential comparison with predictions of photoionization models, since the emission-line spectrum will change in response to the variable ionizing continuum flux. Such a differential comparison between observation and theory should be more reliable than attempts to match absolute intensities because errors in the atomic data base should tend to cancel out.

  2. Emissions variability processor (EMVAP): design, evaluation, and application.

    Science.gov (United States)

    Paine, Robert; Szembek, Carlos; Heinold, David; Knipping, Eladio; Kumar, Naresh

    2014-12-01

    Emissions of pollutants such as SO2 and NOx from external combustion sources can vary widely depending on fuel sulfur content, load, and transient conditions such as startup, shutdown, and maintenance/malfunction. While monitoring will automatically reflect variability from both emissions and meteorological influences, dispersion modeling has been typically conducted with a single constant peak emission rate. To respond to the need to account for emissions variability in addressing probabilistic 1-hr ambient air quality standards for SO2 and NO2, we have developed a statistical technique, the Emissions Variability Processor (EMVAP), which can account for emissions variability in dispersion modeling through Monte Carlo sampling from a specified frequency distribution of emission rates. Based upon initial AERMOD modeling of from 1 to 5 years of actual meteorological conditions, EMVAP is used as a postprocessor to AERMOD to simulate hundreds or even thousands of years of concentration predictions. This procedure uses emissions varied hourly with a Monte Carlo sampling process that is based upon the user-specified emissions distribution, from which a probabilistic estimate can be obtained of the controlling concentration. EMVAP can also accommodate an advanced Tier 2 NO2 modeling technique that uses a varying ambient ratio method approach to determine the fraction of total oxides of nitrogen that are in the form of nitrogen dioxide. For the case of the 1-hr National Ambient Air Quality Standards (NAAQS, established for SO2 and NO2), a "critical value" can be defined as the highest hourly emission rate that would be simulated to satisfy the standard using air dispersion models assuming constant emissions throughout the simulation. The critical value can be used as the starting point for a procedure like EMVAP that evaluates the impact of emissions variability and uses this information to determine an appropriate value to use for a longer-term (e.g., 30-day) average

  3. Changes in Sea Salt Emissions Enhance ENSO Variability

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang; Russell, Lynn M.; Lou, Sijia; Lamjiri, Maryam A.; Liu, Ying; Singh, Balwinder; Ghan, Steven J.

    2016-11-15

    Two 150-year pre-industrial simulations with and without interactive sea salt emissions from the Community Earth System Model (CESM) are performed to quantify the interactions between sea salt emissions and El Niño–Southern Oscillation (ENSO). Variations in sea salt emissions over the tropical Pacific Ocean are affected by changing wind speed associated with ENSO variability. ENSO-induced interannual variations in sea salt emissions result in decreasing (increasing) aerosol optical depth (AOD) by 0.03 over the equatorial central-eastern (western) Pacific Ocean during El Niño events compared to those during La Niña events. These changes in AOD further increase (decrease) radiative fluxes into the atmosphere by +0.2 W m-2 (-0.4 W m-2) over the tropical eastern (western) Pacific. Thereby, sea surface temperature increases (decreases) by 0.2–0.4 K over the tropical eastern (western) Pacific Ocean during El Niño compared to La Niña events and enhances ENSO variability by 10%. The increase in ENSO amplitude is a result of systematic heating (cooling) during the warm (cold) phase, of ENSO in the eastern Pacific. Interannual variations in sea salt emissions then produce the anomalous ascent (subsidence) over the equatorial eastern (western) Pacific between El Niño and La Niña events, which is a result of heating anomalies. Due to variations in sea salt emissions, the convective precipitation is enhanced by 0.6–1.2 mm day-1 over the tropical central-eastern Pacific Ocean and weakened by 0.9–1.5 mm day-1 over the Maritime Continent during El Niño compared to La Niña events, enhancing the precipitation variability over the tropical Pacific.

  4. Variable Emissivity Electrochromics using Ionic Electrolytes and Low Solar Absorptance Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This work further developed a highly promising variable emissivity technology for spacecraft thermal control, based on unique conducting polymer (CP) electrochromics...

  5. Determinants of spatial variability of methane emissions from wet grasslands on peat soil

    NARCIS (Netherlands)

    Pol-Van Dasselaar, van den A.; Beusichem, van M.L.; Oenema, O.

    1999-01-01

    Methane (CH4) emissions from soils, representing the consequence of CH4 production, CH4 consumption and CH4 transport, are poorly characterised and show a large spatial variability. This study aimed to assess the determinants of field-scale spatial variability of CH4 emissions from wet grasslands on

  6. Spatiotemporal Variability of Methane Emissions at Oil and Natural Gas Operations in the Eagle Ford Basin.

    Science.gov (United States)

    Lavoie, Tegan N; Shepson, Paul B; Cambaliza, Maria O L; Stirm, Brian H; Conley, Stephen; Mehrotra, Shobhit; Faloona, Ian C; Lyon, David

    2017-07-18

    Methane emissions from oil and gas facilities can exhibit operation-dependent temporal variability; however, this variability has yet to be fully characterized. A field campaign was conducted in June 2014 in the Eagle Ford basin, Texas, to examine spatiotemporal variability of methane emissions using four methods. Clusters of methane-emitting sources were estimated from 14 aerial surveys of two ("East" or "West") 35 × 35 km grids, two aircraft-based mass balance methods measured emissions repeatedly at five gathering facilities and three flares, and emitting equipment source-types were identified via helicopter-based infrared camera at 13 production and gathering facilities. Significant daily variability was observed in the location, number (East: 44 ± 20% relative standard deviation (RSD), N = 7; West: 37 ± 30% RSD, N = 7), and emission rates (36% of repeat measurements deviate from mean emissions by at least ±50%) of clusters of emitting sources. Emission rates of high emitters varied from 150-250 to 880-1470 kg/h and regional aggregate emissions of large sources (>15 kg/h) varied up to a factor of ∼3 between surveys. The aircraft-based mass balance results revealed comparable variability. Equipment source-type changed between surveys and alterations in operational-mode significantly influenced emissions. Results indicate that understanding temporal emission variability will promote improved mitigation strategies and additional analysis is needed to fully characterize its causes.

  7. Industrial emissions cause extreme urban ozone diurnal variability.

    Science.gov (United States)

    Zhang, Renyi; Lei, Wenfang; Tie, Xuexi; Hess, Peter

    2004-04-27

    Simulations with a regional chemical transport model show that anthropogenic emissions of volatile organic compounds and nitrogen oxides (NO(x) = NO + NO(2)) lead to a dramatic diurnal variation of surface ozone (O(3)) in Houston, Texas. During the daytime, photochemical oxidation of volatile organic compounds catalyzed by NO(x) results in episodes of elevated ambient O(3) levels significantly exceeding the National Ambient Air Quality Standard. The O(3) production rate in Houston is significantly higher than those found in other cities over the United States. At night, a surface NO(x) maximum occurs because of continuous NO emission from industrial sources, and, consequently, an extensive urban-scale "hole" of surface ozone (<10 parts per billion by volume in the entire Houston area) is formed as a result of O(3) removal by NO. The results suggest that consideration of regulatory control of O(3) precursor emissions from the industrial sources is essential to formulate ozone abatement strategies in this region.

  8. Estimation of intersubject variability of cerebral blood flow measurements using MRI and positron emission tomography

    DEFF Research Database (Denmark)

    Henriksen, Otto Mølby; Larsson, Henrik B W; Hansen, Adam E

    2012-01-01

    PURPOSE: To investigate the within and between subject variability of quantitative cerebral blood flow (CBF) measurements in normal subjects using various MRI techniques and positron emission tomography (PET). MATERIALS AND METHODS: Repeated CBF measurements were performed in 17 healthy, young...

  9. Review on Variable Emissivity Materials and Devices Based on Smart Chromism

    Science.gov (United States)

    Lang, FengPei; Wang, Hao; Zhang, ShengJun; Liu, JingBing; Yan, Hui

    2018-01-01

    Variable emissivity material (VEM) can dynamically vary its emissivity and infrared radiation under certain conditions, which may find potential applications in infrared stealth/camouflage, solar thermal collector, spacecraft thermal control, and smart energy-saving windows. In this paper, the variable emissivity materials and devices based on electrochromism and thermochromism are introduced. The basic principle and present status of the research in these fields are overviewed. Four kinds of representative VEMs are extensively summarized, which are tungsten trioxides (WO3), conducting polymers (CPs), perovskite oxides (A_{1-{x}}B_{{x}}MO3), and vanadium dioxide (VO2). Finally, specific issues confronted with electrochromic and thermochromic materials and devices are prospected.

  10. Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

    DEFF Research Database (Denmark)

    Schelde, Kirsten; Cellier, P; Bertolini, T

    2012-01-01

    Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O...... emissions during spring 2009 were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes...

  11. Costs of solar and wind power variability for reducing CO2 emissions.

    Science.gov (United States)

    Lueken, Colleen; Cohen, Gilbert E; Apt, Jay

    2012-09-04

    We compare the power output from a year of electricity generation data from one solar thermal plant, two solar photovoltaic (PV) arrays, and twenty Electric Reliability Council of Texas (ERCOT) wind farms. The analysis shows that solar PV electricity generation is approximately one hundred times more variable at frequencies on the order of 10(-3) Hz than solar thermal electricity generation, and the variability of wind generation lies between that of solar PV and solar thermal. We calculate the cost of variability of the different solar power sources and wind by using the costs of ancillary services and the energy required to compensate for its variability and intermittency, and the cost of variability per unit of displaced CO(2) emissions. We show the costs of variability are highly dependent on both technology type and capacity factor. California emissions data were used to calculate the cost of variability per unit of displaced CO(2) emissions. Variability cost is greatest for solar PV generation at $8-11 per MWh. The cost of variability for solar thermal generation is $5 per MWh, while that of wind generation in ERCOT was found to be on average $4 per MWh. Variability adds ~$15/tonne CO(2) to the cost of abatement for solar thermal power, $25 for wind, and $33-$40 for PV.

  12. The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines

    Science.gov (United States)

    Sun, Mouyuan; Trump, Jonathan R.; Shen, Yue; Brandt, W. N.; Dawson, Kyle; Denney, Kelly D.; Hall, Patrick B.; Ho, Luis C.; Horne, Keith; Jiang, Linhua; Richards, Gordon T.; Schneider, Donald P.; Bizyaev, Dmitry; Kinemuchi, Karen; Oravetz, Daniel; Pan, Kaike; Simmons, Audrey

    2015-09-01

    We explore the variability of quasars in the Mg ii and {{H}}β broad emission lines and ultraviolet/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over 6 months, containing 357 quasars with Mg ii and 41 quasars with {{H}}β . On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional 2854 quasars with Mg ii and 572 quasars with {{H}}β . The Mg ii emission line is significantly variable ({{Δ }}f/f∼ 10% on ∼100-day timescales), a necessary prerequisite for its use for reverberation mapping studies. The data also confirm that continuum variability increases with timescale and decreases with luminosity, and the continuum light curves are consistent with a damped random-walk model on rest-frame timescales of ≳ 5 days. We compare the emission-line and continuum variability to investigate the structure of the broad-line region. Broad-line variability shows a shallower increase with timescale compared to the continuum emission, demonstrating that the broad-line transfer function is not a δ-function. {{H}}β is more variable than Mg ii (roughly by a factor of ∼1.5), suggesting different excitation mechanisms, optical depths and/or geometrical configuration for each emission line. The ensemble spectroscopic variability measurements enabled by the SDSS-RM project have important consequences for future studies of reverberation mapping and black hole mass estimation of 1\\lt z\\lt 2 quasars.

  13. Near-Field Characterization of Methane Emission Variability from a Compressor Station Using a Model Aircraft.

    Science.gov (United States)

    Nathan, Brian J; Golston, Levi M; O'Brien, Anthony S; Ross, Kevin; Harrison, William A; Tao, Lei; Lary, David J; Johnson, Derek R; Covington, April N; Clark, Nigel N; Zondlo, Mark A

    2015-07-07

    A model aircraft equipped with a custom laser-based, open-path methane sensor was deployed around a natural gas compressor station to quantify the methane leak rate and its variability at a compressor station in the Barnett Shale. The open-path, laser-based sensor provides fast (10 Hz) and precise (0.1 ppmv) measurements of methane in a compact package while the remote control aircraft provides nimble and safe operation around a local source. Emission rates were measured from 22 flights over a one-week period. Mean emission rates of 14 ± 8 g CH4 s(-1) (7.4 ± 4.2 g CH4 s(-1) median) from the station were observed or approximately 0.02% of the station throughput. Significant variability in emission rates (0.3-73 g CH4 s(-1) range) was observed on time scales of hours to days, and plumes showed high spatial variability in the horizontal and vertical dimensions. Given the high spatiotemporal variability of emissions, individual measurements taken over short durations and from ground-based platforms should be used with caution when examining compressor station emissions. More generally, our results demonstrate the unique advantages and challenges of platforms like small unmanned aerial vehicles for quantifying local emission sources to the atmosphere.

  14. Global terrestrial isoprene emission models: sensitivity to variability in climate and vegetation

    Directory of Open Access Journals (Sweden)

    A. Arneth

    2011-08-01

    Full Text Available Due to its effects on the atmospheric lifetime of methane, the burdens of tropospheric ozone and growth of secondary organic aerosol, isoprene is central among the biogenic compounds that need to be taken into account for assessment of anthropogenic air pollution-climate change interactions. Lack of process-understanding regarding leaf isoprene production as well as of suitable observations to constrain and evaluate regional or global simulation results add large uncertainties to past, present and future emissions estimates. Focusing on contemporary climate conditions, we compare three global isoprene models that differ in their representation of vegetation and isoprene emission algorithm. We specifically aim to investigate the between- and within model variation that is introduced by varying some of the models' main features, and to determine which spatial and/or temporal features are robust between models and different experimental set-ups. In their individual standard configurations, the models broadly agree with respect to the chief isoprene sources and emission seasonality, with maximum monthly emission rates around 20–25 Tg C, when averaged by 30-degree latitudinal bands. They also indicate relatively small (approximately 5 to 10 % around the mean interannual variability of total global emissions. The models are sensitive to changes in one or more of their main model components and drivers (e.g., underlying vegetation fields, climate input which can yield increases or decreases in total annual emissions of cumulatively by more than 30 %. Varying drivers also strongly alters the seasonal emission pattern. The variable response needs to be interpreted in view of the vegetation emission capacities, as well as diverging absolute and regional distribution of light, radiation and temperature, but the direction of the simulated emission changes was not as uniform as anticipated. Our results highlight the need for modellers to evaluate their

  15. Heterogeneity of gaseous emissions in soils-spatial vs temporal variability

    Science.gov (United States)

    Cardenas, Laura; Chadwick, David; Misselbrook, Tom; Donovan, Neil; Dunn, Rob; Griffith, Bruce; Orr, Robert; Smith, Keith; Rees, Robert M.; Bell, Madeleine; Watson, Catherine; McGeough, Karen; McNeill, Gavin; Williams, John; Cloy, Joanna; Thorman, Rachel; Dhanoa, Dan

    2015-04-01

    Nitrous oxide (N2O) plays a dual role in the atmosphere as a greenhouse gas and via its influence on stratospheric ozone chemistry. The main source of N2O is agricultural soil, with an estimated 96 kt emitted from this source in the UK in 2012 (ca. 83% of the total UK N2O emissions). Microbial transformations such as nitrification, denitrification and chemodenitrification are responsible for these emissions. Soil texture and structure and land management practices (including presence of livestock) -- soil wetness, aeration, temperature and mineral N content -- influence the magnitude of the emissions. Heterogeneity in nutrient distribution and moisture, i.e. hot spots, create spatial variations in the main drivers of these transformations. Studies at laboratory scale are aimed to minimize the variability encountered in the field but although they provide important information on the controlling factors of the soil processes, they are not useful for real quantification. Daily and seasonal variation (temporal) in soil conditions (chemistry, physics and biology) and thus in emissions also occurs. This variability makes it a difficult challenge to quantify emissions and currently makes the soil source the largest contributor to the overall uncertainty of the UK greenhouse gas inventory. Here we present results of a statistical study on the variability of N2O emissions from measurements using the static chamber technique for a variety of N sources. Results from measurements using automated chambers are also presented. Part of the work was funded by the UK government to improve the quantification of this source by measuring emissions from sites with contrasting soil, climate and land management combinations. We also include results from measurements carried out with automated chambers on the UK National Capability Farm Platform in the South West of England. The results show that spatial variability largely contributes to the uncertainty of emissions but temporal

  16. Tidal variability in methane and nitrous oxide emissions along a subtropical estuarine gradient

    Science.gov (United States)

    Sturm, Katrin; Werner, Ursula; Grinham, Alistair; Yuan, Zhiguo

    2017-06-01

    This study investigates the tidal variability in methane (CH4) and nitrous oxide (N2O) emissions along a gradient of the subtropical Brisbane River estuary. Sampling was conducted at the upper, middle and lower reaches over two tidal cycles in 2013 and 2014. Methane and N2O emissions varied significantly over tidal cycles at all sites. Methane and N2O emissions measured at all locations and in both campaigns varied substantially in time, with the maximum to minimum flux ratio in a cycle varying between 2.5 - 9 and 1.7-4.7 times, respectively. Methane emissions peaked just before or at slack tides. In comparison, no clear patterns were observed between the N2O emissions and the tidal cycle despite there being large variations in N2O emissions in some cases. Methane concentrations were elevated during low tides whereas N2O concentrations showed no clear pattern over the tidal cycle. Surface water concentrations and tidal currents played important roles in CH4 and N2O emissions, but wind did not. Our findings show that measurements at a single point in time and site would result in significant errors in CH4 and N2O emission estimates. An adequate and careful sampling scheme is required to capture spatial and temporal variations of CH4 and N2O emissions and surface water concentrations which should cover at least one tidal cycle in different estuarine sections.

  17. Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Peterson, B. M.

    2005-01-01

    We study the low-contrast Fe II emission blends in the ultraviolet (1250--2200A) and optical (4000--6000A) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability...... of the optical Fe II emission is 50% - 75% that of Hbeta and the ultraviolet Fe II emission varies with an even larger amplitude than Hbeta. However, accurate measurement of the flux in these blends proves to be very difficult even using excellent Fe II templates to fit the spectra. We are able to constrain only...... weakly the optical Fe II emission-line response timescale to a value less than several weeks; this upper limit exceeds all the reliably measured emission-line lags in this source so it is not particularly meaningful. Nevertheless, the fact that the optical Fe II and continuum flux variations...

  18. Total electron count variability and stratospheric ozone effects on solar backscatter and LWIR emissions

    Science.gov (United States)

    Ross, John S.; Fiorino, Steven T.

    2017-05-01

    The development of an accurate ionospheric Total Electron Count (TEC) model is of critical importance to high frequency (HF) radio propagation and satellite communications. However, the TEC is highly variable and is continually influenced by geomagnetic storms, extreme UV radiation, and planetary waves. Being able to capture this variability is essential to improve current TEC models. The growing body of data involving ionospheric fluctuations and stratospheric variations has revealed a correlation. In particular, there is a marked and persistent association between increases in stratospheric ozone and variability of the TEC. The spectral properties of ozone show that it is a greenhouse gas that alters long wave emissions from Earth and interacts with the UV spectrum coming from the sun. This study uses the Laser Environment Effects Definition and Reference (LEEDR) radiative transfer and atmospheric characterization code to model the effects of changes in stratospheric ozone on solar backscatter and longwave (LWIR) terrestrial emissions and infer TEC and TEC variability.

  19. Variabilities detected by acoustic emission from filament-wound Aramid fiber/epoxy composite pressure vessels

    Science.gov (United States)

    Hamstad, M. A.

    1978-01-01

    Two hundred and fifty Aramid fiber/epoxy pressure vessels were filament-wound over spherical aluminum mandrels under controlled conditions typical for advanced filament-winding. A random set of 30 vessels was proof-tested to 74% of the expected burst pressure; acoustic emission data were obtained during the proof test. A specially designed fixture was used to permit in situ calibration of the acoustic emission system for each vessel by the fracture of a 4-mm length of pencil lead (0.3 mm in diameter) which was in contact with the vessel. Acoustic emission signatures obtained during testing showed larger than expected variabilities in the mechanical damage done during the proof tests. To date, identification of the cause of these variabilities has not been determined.

  20. Spatial and temporal variability of greenhouse gas emissions from a small and shallow temperate lake

    Science.gov (United States)

    Praetzel, Leandra; Schmiedeskamp, Marcel; Broder, Tanja; Hüttemann, Caroline; Jansen, Laura; Metzelder, Ulrike; Wallis, Ronya; Knorr, Klaus-Holger; Blodau, Christian

    2017-04-01

    Small inland waters (lakes. They are further expected to be susceptible to changing climate conditions. So far, little is known about the spatial and temporal variability of carbon dioxide (CO2) and methane (CH4) emissions and in-lake dynamics of CH4 production and oxidation in small, epilimnetic lakes in the temperate zone. Of particular interest is the potential occurrence of "hot spots" and "hot moments" that could contribute significantly to total emissions. To address this knowledge gap, we determined CO2 and CH4 emissions and dynamics to identify their controlling environmental factors in a polymictic small (1.4 ha) and shallow (max. depth approx. 1.5 m) crater lake ("Windsborn") in the Eifel uplands in south-west Germany. As Lake Windsborn has a small catchment area (8 ha) and no surficial inflows, it serves well as a model system for the identification of factors and processes controlling emissions. In 2015, 2016 and 2017 we measured CO2 and CH4 gas fluxes with different techniques across the sediment/water and water/atmosphere interface. Atmospheric exchange was measured using mini-chambers equipped with CO2 sensors and with an infra-red greenhouse gas analyzer for high temporal resolution flux measurements. Ebullition of CH4 was quantified with funnel traps. Sediment properties were examined using pore-water peepers. All measurements were carried out along a transect covering both littoral and central parts of the lake. Moreover, a weather station on a floating platform in the center of the lake recorded meteorological data as well as CO2 concentration in different depths of the water column. So far, Lake Windsborn seems to be a source for both CO2 and CH4 on an annual scale. CO2 emissions generally increased from spring to summer. Even though CO2 uptake could be observed during some periods in spring and fall, CO2 emissions in the summer exceeded the uptake. CO2 and CH4 emissions also appeared to be spatially variable between littoral areas and the inner

  1. Variability of fire emissions on interannual to multi-decadal timescales in two Earth System models

    Science.gov (United States)

    Ward, D. S.; Shevliakova, E.; Malyshev, S.; Lamarque, J.-F.; Wittenberg, A. T.

    2016-12-01

    Connections between wildfires and modes of variability in climate are sought as a means for predicting fire activity on interannual to multi-decadal timescales. Several fire drivers, such as temperature and local drought index, have been shown to vary on these timescales, and analysis of tree-ring data suggests covariance between fires and climate oscillation indices in some regions. However, the shortness of the satellite record of global fire events limits investigations on larger spatial scales. Here we explore the interplay between climate variability and wildfire emissions with the preindustrial long control numerical experiments and historical ensembles of CESM1 and the NOAA/GFDL ESM2Mb. We find that interannual variability in fires is underpredicted in both Earth System models (ESMs) compared to present day fire emission inventories. Modeled fire emissions respond to the El Niño/southern oscillation (ENSO) and Pacific decadal oscillation (PDO) with increases in southeast Asia and boreal North America emissions, and decreases in southern North America and Sahel emissions, during the ENSO warm phase in both ESMs, and the PDO warm phase in CESM1. Additionally, CESM1 produces decreases in boreal northern hemisphere fire emissions for the warm phase of the Atlantic Meridional Oscillation. Through analysis of the long control simulations, we show that the 20th century trends in both ESMs are statistically significant, meaning that the signal of anthropogenic activity on fire emissions over this time period is detectable above the annual to decadal timescale noise. However, the trends simulated by the two ESMs are of opposite sign (CESM1 decreasing, ESM2Mb increasing), highlighting the need for improved understanding, proxy observations, and modeling to resolve this discrepancy.

  2. Social, economic, and resource predictors of variability in household air pollution from cookstove emissions.

    Directory of Open Access Journals (Sweden)

    Gautam N Yadama

    Full Text Available We examine if social and economic factors, fuelwood availability, market and media access are associated with owning a modified stove and variation in household emissions from biomass combustion, a significant environmental and health concern in rural India. We analyze cross-sectional household socio-economic data, and PM(2.5 and particulate surface area concentration in household emissions from cookstoves (n=100. This data set combines household social and economic variables with particle emissions indexes associated with the household stove. The data are from the Foundation for Ecological Society, India, from a field study of household emissions. In our analysis, we find that less access to ready and free fuelwood and higher wealth are associated with owning a replacement/modified stove. We also find that additional kitchen ventilation is associated with a 12% reduction in particulate emissions concentration (p<0.05, after we account for the type of stove used. We did not find a significant association between replacement/modified stove on household emissions when controlling for additional ventilation. Higher wealth and education are associated with having additional ventilation. Social caste, market and media access did not have any effect on the presence of replacement or modified stoves or additional ventilation. While the data available to us does not allow an examination of direct health outcomes from emissions variations, adverse environmental and health impacts of toxic household emissions are well established elsewhere in the literature. The value of this study is in its further examination of the role of social and economic factors and available fuelwood from commons in type of stove use, and additional ventilation, and their effect on household emissions. These associations are important since the two direct routes to improving household air quality among the poor are stove type and better ventilation.

  3. Vehicle NOx emission plume isotopic signatures: Spatial variability across the eastern United States

    Science.gov (United States)

    Miller, David J.; Wojtal, Paul K.; Clark, Sydney C.; Hastings, Meredith G.

    2017-04-01

    On-road vehicle nitrogen oxide (NOx) sources currently dominate the U.S. anthropogenic emission budgets, yet vehicle NOx emissions have uncertain contributions to oxidized nitrogen (N) deposition patterns. Isotopic signatures serve as a potentially valuable observational tool to trace source contributions to NOx chemistry and N deposition, yet in situ emission signatures are underconstrained. We characterize the spatiotemporal variability of vehicle NOx emission isotopic signatures (δ15N-NOx) representative of U.S. vehicle fleet-integrated emission plumes. A novel combination of on-road mobile and stationary urban measurements is performed using a field and laboratory-verified technique for actively capturing NOx in solution to quantify δ15N-NOx at hourly resolution. On-road δ15N-NOx upwind of Providence, RI, ranged from -7 to -3‰. Simultaneous urban background δ15N-NOx observations showed comparable range and variations with on-road measurements, suggesting that vehicles dominate NOx emissions in the Providence area. On-road spatial δ15N-NOx variations of -9 to -2‰ were observed under various driving conditions in six urban metropolitan areas and rural interstate highways during summer and autumn in the U.S. Northeast and Midwest. Although isotopic signatures were insensitive to on-road driving mode variations, statistically significant correlations were found between δ15N-NOx and NOx emission factor extremes associated with heavy diesel emitter contributions. Overall, these results constrain an isotopic signature of fleet-integrated roadway NOx emission plumes, which have important implications for distinguishing vehicle NOx from other sources and tracking emission contributions to NOx chemistry and N deposition.

  4. PM(10) emission forecasting using artificial neural networks and genetic algorithm input variable optimization.

    Science.gov (United States)

    Antanasijević, Davor Z; Pocajt, Viktor V; Povrenović, Dragan S; Ristić, Mirjana Đ; Perić-Grujić, Aleksandra A

    2013-01-15

    This paper describes the development of an artificial neural network (ANN) model for the forecasting of annual PM(10) emissions at the national level, using widely available sustainability and economical/industrial parameters as inputs. The inputs for the model were selected and optimized using a genetic algorithm and the ANN was trained using the following variables: gross domestic product, gross inland energy consumption, incineration of wood, motorization rate, production of paper and paperboard, sawn wood production, production of refined copper, production of aluminum, production of pig iron and production of crude steel. The wide availability of the input parameters used in this model can overcome a lack of data and basic environmental indicators in many countries, which can prevent or seriously impede PM emission forecasting. The model was trained and validated with the data for 26 EU countries for the period from 1999 to 2006. PM(10) emission data, collected through the Convention on Long-range Transboundary Air Pollution - CLRTAP and the EMEP Programme or as emission estimations by the Regional Air Pollution Information and Simulation (RAINS) model, were obtained from Eurostat. The ANN model has shown very good performance and demonstrated that the forecast of PM(10) emission up to two years can be made successfully and accurately. The mean absolute error for two-year PM(10) emission prediction was only 10%, which is more than three times better than the predictions obtained from the conventional multi-linear regression and principal component regression models that were trained and tested using the same datasets and input variables. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Mira Variable Stars from LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection

    Science.gov (United States)

    Yao, Yuhan; Liu, Chao; Deng, Licai; de Grijs, Richard; Matsunaga, Noriyuki

    2017-09-01

    Based on an extensive spectral study of a photometrically confirmed sample of Mira variables, we find a relationship between the relative Balmer emission-line strengths and spectral temperatures of O-rich Mira stars. The {F}{{H}δ }/{F}{{H}γ } flux ratio increases from less than unity to five as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions. We also discuss the relationship between the equivalent widths of the Balmer emission lines and the photometric luminosity phase of our Mira sample stars. Using our 291 Mira spectra as templates for reference, 191 Mira candidates are newly identified from the LAMOST DR4 catalog. We summarize the criteria adopted to select Mira candidates based on emission-line indices and molecular absorption bands. This enlarged spectral sample of Mira variables has the potential to contribute significantly to our knowledge of the optical properties of Mira stars and will facilitate further studies of these late-type, long-period variables.

  6. BROAD Hβ EMISSION-LINE VARIABILITY IN A SAMPLE OF 102 LOCAL ACTIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Runco, Jordan N.; Cosens, Maren; Bennert, Vardha N.; Scott, Bryan [Physics Department, California Polytechnic State University, San Luis Obispo CA 93407 (United States); Komossa, S. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany); Malkan, Matthew A.; Treu, Tommaso [Department of Physics, University of California, Los Angeles, CA 90095 (United States); Lazarova, Mariana S. [Department of Physics and Physical Science, University of Nebraska Kearney, Kearney, NE 68849 (United States); Auger, Matthew W. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Park, Daeseong, E-mail: jrunco@calpoly.edu, E-mail: mcosens@calpoly.edu, E-mail: vbennert@calpoly.edu, E-mail: malkan@astro.ucla.edu, E-mail: tt@physics.ucsb.edu, E-mail: lazarovam2@unk.edu, E-mail: mauger@ast.cam.ac.uk, E-mail: daeseongpark@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon, 34055 (Korea, Republic of)

    2016-04-10

    A sample of 102 local (0.02 ≤ z ≤ 0.1) Seyfert galaxies with black hole masses M{sub BH} > 10{sup 7}M{sub ⊙} was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M{sub BH} and host galaxy properties. We study profile changes of the broad Hβ emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad Hβ emission line is of particular interest, not only because it is used to estimate M{sub BH}, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (∼66%) of the objects, resulting in a Seyfert-type change for ∼38% of the objects, likely driven by variable accretion and/or obscuration. The broad Hβ line virtually disappears in 3/102 (∼3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study provides statistical information on the frequency of Hβ line variability in a sample of low-redshift Seyfert galaxies.

  7. Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

    Directory of Open Access Journals (Sweden)

    K. Schelde

    2012-08-01

    Full Text Available Nitrous oxide (N2O emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha−1 yr−1 and 5.5 kg N2O-N ha−1 yr−1 during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.

  8. Interannual variability in global biomass burning emissions from 1997 to 2004

    Directory of Open Access Journals (Sweden)

    G. R. van der Werf

    2006-01-01

    Full Text Available Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001–2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006. ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP, heterotrophic respiration (Rh, and biomass burning, using time varying inputs of precipitation (PPT, temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR. For the 1997–2004 period, we found that on average approximately 58 Pg C year−1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via Rh. Another 4%, or 2.5 Pg C year−1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics, whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year−1, with a maximum in 1998 (3.2 Pg C year−1 and a minimum in 2000 (2.0 Pg C year−1.

  9. Diurnal variability of CO2 and CH4 emissions from tropical reservoirs

    Science.gov (United States)

    Linkhorst, Annika; Reinaldo Paranaíba, José; Barros, Nathan; DelSontro, Tonya; Isidorova, Anastasija; Mendonça, Raquel; Sobek, Sebastian

    2017-04-01

    -of-the-art techniques to show, for the first time, short-scale temporal variability for both diffusion and ebullition of CO2 and CH4 in different tropical reservoirs. It shows substantial and non-negligable diurnal variability in GHG emission from tropical reservoirs. Further studies are needed to find out if the pattern of low flux during night needs to be accounted for in estimations of GHG emission from reservoirs.

  10. Center-to-Limb Variability of Hot Coronal EUV Emissions During Solar Flares

    Science.gov (United States)

    Thiemann, E. M. B.; Chamberlin, P. C.; Eparvier, F. G.; Epp, L.

    2018-02-01

    It is generally accepted that densities of quiet-Sun and active region plasma are sufficiently low to justify the optically thin approximation, and this is commonly used in the analysis of line emissions from plasma in the solar corona. However, the densities of solar flare loops are substantially higher, compromising the optically thin approximation. This study begins with a radiative transfer model that uses typical solar flare densities and geometries to show that hot coronal emission lines are not generally optically thin. Furthermore, the model demonstrates that the observed line intensity should exhibit center-to-limb variability (CTLV), with flares observed near the limb being dimmer than those occurring near disk center. The model predictions are validated with an analysis of over 200 flares observed by the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO), which uses six lines, with peak formation temperatures between 8.9 and 15.8 MK, to show that limb flares are systematically dimmer than disk-center flares. The data are then used to show that the electron column density along the line of sight typically increases by 1.76 × 10^{19} cm^{-2} for limb flares over the disk-center flare value. It is shown that the CTLV of hot coronal emissions reduces the amount of ionizing radiation propagating into the solar system, and it changes the relative intensities of lines and bands commonly used for spectral analysis.

  11. Spatial and Seasonal Variability of Temperature in CO2 Emission from Mars' Mesosphere

    Science.gov (United States)

    Livengood, Timothy A.; Kostiuk, Theodor; Hewagama, Tilak; Kolasinski, John R.; Henning, Wade; Fast, Kelly Elizabeth; Sonnabend, Guido; Sornig, Manuela

    2017-10-01

    We have observed non-local thermodynamic equilibrium (non-LTE) emission of carbon dioxide that probes Mars’ mesosphere in 2001, 2003, 2007, 2012, 2014, and 2016. These measurements were conducted at 10.6 μm wavelength using the Goddard Space Flight Center Heterodyne Instrument for Planetary Winds and Composition (HIPWAC) from the NASA Infrared Telescope Facility (IRTF) at resolving power (1-33)×106. The Maxwellian broadening of the emission line can be measured at this resolution, providing a direct determination of temperature in the mesosphere. The nonLTE line appears as a narrow emission core within a broad absorption formed by tropospheric CO2, which provides temperature information reaching down to the martian surface, while the mesospheric line probes temperature at about 60-80 km altitude. We will report on the spatial distribution of temperature and emission line strength with local solar time on Mars, with latitude, as well as long-term variability including seasonal effects that modify the overall thermal structure of the atmosphere. These remote measurements complement results from orbital spacecraft through access to a broad range of local solar time on each occasion.This work has been supported by the NASA Planetary Astronomy and Solar Systems Observations Programs

  12. Variability of Disk Emission in Pre-Main Sequence and Related Stars. II. Variability in the Gas and Dust Emission of the Herbig Fe Star SAO 206462

    Science.gov (United States)

    Sitko, Michael L.; Day, Amanda N.; Kimes, Robin L.; Beerman, Lori C.; Martus, Cameron; Lynch, David K.; Russell, Ray W.; Grady, Carol A.; Schneider, Glenn; Lisse, Carey M.; hide

    2011-01-01

    We present thirteen epochs of near-infrared (0.8-5 microns) spectroscopic observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (Br(alpha) , Br(gamma), Pa(beta), Pa(delta), Pa(epsilon), and the 0.8446 microns line of O I) along with continuum measurements made near the standard J, H, K, and L photometric bands were measured. A mass accretion rate of approximately 2 x 10(exp 8)Solar Mass/yr was derived from the Br(gamma) and Pa(beta) lines. However, the fluxes of these lines varied by a factor of over two during the course of a few months. The continuum also varied, but by only approx.30%, and even decreased at a time when the gas emission was increasing. The H I line at 1.083 microns was also found to vary in a manner inconsistent with that of either the hydrogen lines or the dust. Both the gas and dust variabilities indicate significant changes in the region of the inner gas and the inner dust belt that may be common to many young disk systems. If planets are responsible for defining the inner edge of the gap, they could interact with the material on time scales commensurate with what is observed for the variations in the dust, while other disk instabilities (thermal, magneto-rotational) would operate there on longer time scales than we observe for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3 years. If the changes are being induced in the disk material closer to the star than the gap, a variety of mechanisms (disk instabilities, interactions via planets) might be responsible for the changes seen. The He I feature is most likely due to a wind whose orientation changes with respect to the observer on time scales of a day or less. To further constrain the origin of the gas and dust emission will require multiple spectroscopic and interferometric observations on both shorter and longer time scales that have been sampled so far.

  13. TIME VARIABLE BROAD-LINE EMISSION IN NGC 4203: EVIDENCE FOR STELLAR CONTRAILS

    Energy Technology Data Exchange (ETDEWEB)

    Devereux, Nick, E-mail: devereux@erau.edu [Department of Physics, Embry-Riddle Aeronautical University, Prescott, AZ 86301 (United States)

    2011-12-10

    Dual epoch spectroscopy of the lenticular galaxy, NGC 4203, obtained with the Hubble Space Telescope has revealed that the double-peaked component of the broad H{alpha} emission line is time variable, increasing by a factor of 2.2 in brightness between 1999 and 2010. Modeling the gas distribution responsible for the double-peaked profiles indicates that a ring is a more appropriate description than a disk and most likely represents the contrail of a red supergiant star that is being tidally disrupted at a distance of {approx}1500 AU from the central black hole. There is also a bright core of broad H{alpha} line emission that is not time variable and identified with a large-scale inflow from an outer radius of {approx}1 pc. If the gas number density is {>=}10{sup 6} cm{sup -3}, as suggested by the absence of similarly broad [O I] and [O III] emission lines, then the steady state inflow rate is {approx} 2 Multiplication-Sign 10{sup -2} M{sub Sun} yr{sup -1}, which exceeds the inflow requirement to explain the X-ray luminosity in terms of radiatively inefficient accretion by a factor of {approx}6. The central active galactic nucleus (AGN) is unable to sustain ionization of the broad-line region; the discrepancy is particularly acute in 2010 when the broad H{alpha} emission line is dominated by the contrail of the infalling supergiant star. However, ram pressure shock ionization produced by the interaction of the infalling supergiant with the ambient interstellar medium may help alleviate the ionizing deficit by generating a mechanical source of ionization supplementing the photoionization provided by the AGN.

  14. Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

    Directory of Open Access Journals (Sweden)

    J. Zhu

    2013-03-01

    Full Text Available Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N, causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O. We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4 at Tieshanping (Chongqing, SW China and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS and a hydrologically connected, terraced groundwater discharge zone (GDZ in the valley bottom. High emission rates of up to 1800 μg N2O-N m−2 h−1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3− in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3− decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m−2 yr−1 for a year with a wet and a dry summer, respectively are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8–10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  15. NON-THERMAL EMISSION FROM CATACLYSMIC VARIABLES: IMPLICATIONS ON ASTROPARTICLE PHYSICS

    Directory of Open Access Journals (Sweden)

    Vojtech Šimon

    2013-12-01

    Full Text Available We review the lines of evidence that some cataclysmic variables (CVs are the sources of non-thermal radiation. It was really observed in some dwarf novae in outburst, a novalike CV in the high state, an intermediate polar, polars, and classical novae (CNe during outburst. The detection of this radiation suggests the presence of highly energetic particles in these CVs. The conditions for the observability of this emission depend on the state of activity, and the system parameters. We review the processes and conditions that lead to the production of this radiation in various spectral bands, from gamma-rays including TeV emission to radio. Synchrotron and cyclotron emissions suggest the presence of strong magnetic fields in CV. In some CVs, e.g. during some dwarf nova outbursts, the magnetic field generated in the accretion disk leads to the synchrotron jets radiating in radio. The propeller effect or a shock in the case of the magnetized white dwarf (WD can lead to a strong acceleration of the particles that produce gamma-ray emission via pi0 decay; even Cherenkov radiation is possible. In addition, a gamma-ray production via pi0 decay was observed in the ejecta of an outburst of a symbiotic CN. Nuclear reactions during thermonuclear runaway in the outer layer of the WD undergoing CN outburst lead to the production of radioactive isotopes; their decay is the source of gamma-ray emission. The production of accelerated particles in CVs often has episodic character with a very small duty cycle; this makes their detection and establishing the relation of the behavior in various bands difficult.

  16. Emission of radiation by a resonance medium excited with a variable superluminal velocity

    Science.gov (United States)

    Arkhipov, R. M.; Pakhomov, A. V.

    2017-05-01

    Specific properties of the radiation emitted by a spatially modulated resonance medium excited by an ultrashort light pulse propagating through the medium at a variable superluminal velocity are analyzed. In so doing, frequencies different from that of the resonance transition of the medium may appear in the emission spectrum. It is demonstrated that, in contrast to an earlier studied case of medium excitation at constant velocity, variation of the excitation velocity leads to generation of a spectral continuum, the boundaries of which are determined by the range of variation of the medium-excitation velocity.

  17. Trends and inter-annual variability of methane emissions derived from 1979-1993 global CTM simulations

    Directory of Open Access Journals (Sweden)

    F. Dentener

    2003-01-01

    Full Text Available The trend and interannual variability of methane sources are derived from multi-annual simulations of tropospheric photochemistry using a 3-D global chemistry-transport model. Our semi-inverse analysis uses the fifteen years (1979--1993 re-analysis of ECMWF meteorological data and annually varying emissions including photo-chemistry, in conjunction with observed CH4 concentration distributions and trends derived from the NOAA-CMDL surface stations. Dividing the world in four zonal regions (45--90 N, 0--45 N, 0--45 S, 45--90 S we find good agreement in each region between (top-down calculated emission trends from model simulations and (bottom-up estimated anthropogenic emission trends based on the EDGAR global anthropogenic emission database, which amounts for the period 1979--1993 2.7 Tg CH4 yr-1. Also the top-down determined total global methane emission compares well with the total of the bottom-up estimates. We use the difference between the bottom-up and top-down determined emission trends to calculate residual emissions. These residual emissions represent the inter-annual variability of the methane emissions. Simulations have been performed in which the year-to-year meteorology, the emissions of ozone precursor gases, and the stratospheric ozone column distribution are either varied, or kept constant. In studies of methane trends it is most important to include the trends and variability of the oxidant fields. The analyses reveals that the variability of the emissions is of the order of 8Tg CH4 yr-1, and likely related to wetland emissions and/or biomass burning.

  18. Seasonal and diurnal variability of N{sub 2}O emissions from a full-scale municipal wastewater treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Daelman, Matthijs R.J., E-mail: m.r.j.daelman@tudelft.nl [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Voorthuizen, Ellen M. van [Royal HaskoningDHV, P.O. Box 151, 6500AD Nijmegen (Netherlands); Dongen, Udo G.J.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Volcke, Eveline I.P. [Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Loosdrecht, Mark C.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO{sub 2}-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research. - Highlights: • Unique dataset of long-term nitrous oxide emission from activated sludge tanks • Emission exhibited pronounced diurnal variability, superimposed on seasonal trend • Seasonal nitrous oxide emission trend correlated with daily nitrite peaks • Emission’s diurnal trend suggests suboptimal oxygen concentrations as cause.

  19. Minor methane emissions from an Alpine hydropower reservoir based on monitoring of diel and seasonal variability.

    Science.gov (United States)

    Sollberger, Sébastien; Wehrli, Bernhard; Schubert, Carsten J; DelSontro, Tonya; Eugster, Werner

    2017-10-18

    We monitored CH4 emissions during the ice-free period of an Alpine hydropower reservoir in the Swiss Alps, Lake Klöntal, to investigate mechanisms responsible for CH4 variability and to estimate overall emissions to the atmosphere. A floating eddy-covariance platform yielded total CH4 and CO2 emission rates at high temporal resolution, while hydroacoustic surveys provided no indication of CH4 ebullition. Higher CH4 fluxes (2.9 ± 0.1 mg CH4 per m2 per day) occurred during the day when surface water temperatures were warmer and wind speeds higher than at night. Piston velocity estimates (k600) showed an upper limit at high wind speeds that may be more generally valid also for other lakes and reservoirs with limited CH4 dissolved in the water body: above 2.0 m s-1 a further increase in wind speed did not lead to higher CH4 fluxes, because under such conditions it is not the turbulent mixing and transport that limits effluxes, but the resupply of CH4 to the lake surface. Increasing CH4 fluxes during the warm season showed a clear spatial gradient once the reservoir started to fill up and flood additional surface area. The warm period contributed 27% of the total CH4 emissions (2.6 t CH4 per year) estimated for the full year and CH4 accounted for 63% of carbonic greenhouse gas emissions. Overall, the average CH4 emissions (1.7 to 2.2 mg CH4 per m2 per day determined independently from surface water samplings and eddy covariance, respectively) were small compared to most tropical and some temperate reservoirs. The resulting greenhouse gas (GHG) emissions in CO2-equivalents revealed that electricity produced in the Lake Klöntal power plant was relatively climate-friendly with a low GHG-to-power output ratio of 1.24 kg CO2,eq per MW h compared to 6.5 and 8.1 kg CO2,eq per MW h associated with the operation of solar photovoltaics and wind energy, respectively, or about 980 kg CO2,eq per MW h for coal-fired power plants.

  20. Biofuels, land use change, and greenhouse gas emissions: some unexplored variables.

    Science.gov (United States)

    Kim, Hyungtae; Kim, Seungdo; Dale, Bruce E

    2009-02-01

    Greenhouse gas release from land use change (the so-called "carbon debt") has been identified as a potentially significant contributor to the environmental profile of biofuels. The time required for biofuels to overcome this carbon debt due to land use change and begin providing cumulative greenhouse gas benefits is referred to as the "payback period" and has been estimated to be 100-1000 years depending on the specific ecosystem involved in the land use change event. Two mechanisms for land use change exist: "direct" land use change, in which the land use change occurs as part of a specific supply chain for a specific biofuel production facility, and "indirect" land use change, in which market forces act to produce land use change in land that is not part of a specific biofuel supply chain, including, for example, hypothetical land use change on another continent. Existing land use change studies did not consider many of the potentially important variables that might affect the greenhouse gas emissions of biofuels. We examine here several variables that have not yet been addressed in land use change studies. Our analysis shows that cropping management is a key factor in estimating greenhouse gas emissions associated with land use change. Sustainable cropping management practices (no-till and no-till plus cover crops) reduce the payback period to 3 years for the grassland conversion case and to 14 years for the forest conversion case. It is significant that no-till and cover crop practices also yield higher soil organic carbon (SOC) levels in corn fields derived from former grasslands or forests than the SOC levels that result if these grasslands or forests are allowed to continue undisturbed. The United States currently does not hold any of its domestic industries responsible for its greenhouse gas emissions. Thus the greenhouse gas standards established for renewable fuels such as corn ethanol in the Energy Independence and Security Act (EISA) of 2007 set a

  1. Methane emissions in the Pantanal, South America, during the low water season - importance of environmental variables and within-lake variability

    Science.gov (United States)

    Bastviken, David; Santoro, Ana Lucia; Marotta, Humberto; Queiroz Pinho, Luana; Calheiros, Debora; Crill, Patrick; Enrich-Prast, Alex

    2010-05-01

    Freshwater environments contribute on the order of 75% of the natural methane (CH4) emissions. While there are indications that tropical lakes emit 58-400 % more CH4 per area unit than similar environments in boreal and temperate biomes, direct measurements of tropical lake emissions are scarce. We measured CH4 emissions from 15 lakes in the Pantanal region of South America, one of the world's largest tropical wetland areas, during the low water period. Measured fluxes ranged from 3.9 to 74.2 mmol m-2 d-1 and the average flux from all studied lakes was 8.79 mmol m-2 d-1 (equivalent to 131.8 mg CH4 m-2 d-1). Ebullition accounted for 91 % of the flux (28-98 % on individual lakes). The use of floating diffusion chambers underlain by a submersed bubble shield in combination with regular, unshielded chambers provides a straightforward way of separating diffusive flux and ebullition. We observed diurnal cycling of emission rates and therefore 24 hour measurements are recommended compared to measurements not accounting for the full diurnal cycle. Within-lake variability of CH4 emissions may be equally or more important than between-lake variability in floodplain areas, and this study identified habitats within lakes having widely different flux rates. Future measurements with static floating chambers should be based on many individual chambers distributed in the various sub-environments shown to differ in emissions in order to account for the within-lake variability.

  2. Nitrous oxide emissions from European agriculture - an analysis of variability and drivers of emissions from field experiments

    DEFF Research Database (Denmark)

    Rees, R M; Agustin, J; Alberti, G

    2013-01-01

    Nitrous oxide emissions from a network of agricultural experiments in Europe were used to explore the relative importance of site and management controls of emissions. At each site, a selection of management interventions were compared within replicated experimental designs in plot-based experime...

  3. Effects of mobile phone emissions on human brain activity and sleep variables.

    Science.gov (United States)

    Hamblin, D L; Wood, A W

    2002-08-01

    To compare the findings of the main studies that have examined the effects of GSM mobile phone radiofrequency emissions on human brain activity and sleep variables. Fourteen published studies reporting on human brain electrical activity measurements during and/or after such radiofrequency emissions were identified and compared. Although, in general, outcomes have been inconsistent and comparison between individual studies is difficult, enhanced electroencephalogram alpha-band power has been noted in several of the studies, a phenomenon also observed in some animal studies. Performance decrements observed in some recent extremely low frequency studies are consistent with enhanced alpha-band power, highlighting the possible role of extremely low frequency fields associated with battery current in mobile phone handsets. However, more complex cognitive tasks appear to show improved performance in relation to mobile phone exposure. Significant cognitive effects have been reported using both modulated and unmodulated radiofrequency carriers. The possibility of putative effects being due to extremely low frequency demodulation is therefore unlikely. There are no obvious associations between the site of exposure and regions of the brain from which effects are reported or implied. Lastly, radiofrequency effects have been reported to occur both during exposure and up to 1 h or so after cessation of exposure.

  4. Estimating greenhouse gas emissions of European cities--modeling emissions with only one spatial and one socioeconomic variable.

    Science.gov (United States)

    Baur, Albert H; Lauf, Steffen; Förster, Michael; Kleinschmit, Birgit

    2015-07-01

    Substantive and concerted action is needed to mitigate climate change. However, international negotiations struggle to adopt ambitious legislation and to anticipate more climate-friendly developments. Thus, stronger actions are needed from other players. Cities, being greenhouse gas emission centers, play a key role in promoting the climate change mitigation movement by becoming hubs for smart and low-carbon lifestyles. In this context, a stronger linkage between greenhouse gas emissions and urban development and policy-making seems promising. Therefore, simple approaches are needed to objectively identify crucial emission drivers for deriving appropriate emission reduction strategies. In analyzing 44 European cities, the authors investigate possible socioeconomic and spatial determinants of urban greenhouse gas emissions. Multiple statistical analyses reveal that the average household size and the edge density of discontinuous dense urban fabric explain up to 86% of the total variance of greenhouse gas emissions of EU cities (when controlled for varying electricity carbon intensities). Finally, based on these findings, a multiple regression model is presented to determine greenhouse gas emissions. It is independently evaluated with ten further EU cities. The reliance on only two indicators shows that the model can be easily applied in addressing important greenhouse gas emission sources of European urbanites, when varying power generations are considered. This knowledge can help cities develop adequate climate change mitigation strategies and promote respective policies on the EU or the regional level. The results can further be used to derive first estimates of urban greenhouse gas emissions, if no other analyses are available. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Spatial variability of oceanic phycoerythrin spectral types derived from airborne laser-induced fluorescence emissions

    Science.gov (United States)

    Hoge, Frank E.; Wright, C. Wayne; Kana, Todd M.; Swift, Robert N.; Yungel, James K.

    1998-07-01

    We report spatial variability of oceanic phycoerythrin spectral types detected by means of a blue spectral shift in airborne laser-induced fluorescence emission. The blue shift of the phycoerythrobilin fluorescence is known from laboratory studies to be induced by phycourobilin chromophore substitution at phycoerythrobilin chromophore sites in some strains of phycoerythrin-containing marine cyanobacteria. The airborne 532-nm laser-induced phycoerythrin fluorescence of the upper oceanic volume showed distinct segregation of cyanobacterial chromophore types in a flight transect from coastal water to the Sargasso Sea in the western North Atlantic. High phycourobilin levels were restricted to the oceanic (oligotrophic) end of the flight transect, in agreement with historical ship findings. These remotely observed phycoerythrin spectral fluorescence shifts have the potential to permit rapid, wide-area studies of the spatial variability of spectrally distinct cyanobacteria, especially across interfacial regions of coastal and oceanic water masses. Airborne laser-induced phytoplankton spectral fluorescence observations also further the development of satellite algorithms for passive detection of phytoplankton pigments. Optical modifications to the NASA Airborne Oceanographic Lidar are briefly described that permitted observation of the fluorescence spectral shifts.

  6. Daily and Hourly Variability in Global Fire Emissions and Consequences for Atmospheric Model Predictions of Carbon Monoxide

    Science.gov (United States)

    Mu, M.; Randerson, J. T.; van der Werf, G. R.; Giglio, L.; Kasibhatla, P.; Morton, D.; Collatz, G. J.; DeFries, R. S.; Hyer, E. J.; Prins, E. M.; hide

    2011-01-01

    Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We distributed monthly GFED3 emissions during 2003-2009 on a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) active fire observations. We found that patterns of daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of bunting in savannas. On diurnal timescales, our analysis of the GOES active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top-down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates.

  7. Daily and 3-hourly Variability in Global Fire Emissions and Consequences for Atmospheric Model Predictions of Carbon Monoxide

    Science.gov (United States)

    Mu, M.; Randerson, J. T.; vanderWerf, G. R.; Giglio, L.; Kasibhatla, P.; Morton, D.; Collatz, G. J.; DeFries, R. S.; Hyer, E. J.; Prins, E. M.; hide

    2011-01-01

    Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We disaggregated monthly GFED3 emissions during 2003.2009 to a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS) ]derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) active fire observations. Daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of burning in savannas. These patterns were consistent with earlier field and modeling work characterizing fire behavior dynamics in different ecosystems. On diurnal timescales, our analysis of the GOES WF_ABBA active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top ]down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from

  8. Satellite observations indicate substantial spatiotemporal variability in biomass burning NOx emission factors for South America

    NARCIS (Netherlands)

    Castellanos, P.; Boersma, K.F.; Werf, van de G.R.

    2014-01-01

    Biomass burning is an important contributor to global total emissions of NOx (NO+NO2). Generally bottom-up fire emissions models calculate NOx emissions by multiplying fuel consumption estimates with static biome-specific emission factors, defined in units of grams of NO per kilogram of dry matter

  9. Variability and uncertainty in life cycle assessment models for greenhouse gas emissions from Canadian oil sands production.

    Science.gov (United States)

    Brandt, Adam R

    2012-01-17

    Because of interest in greenhouse gas (GHG) emissions from transportation fuels production, a number of recent life cycle assessment (LCA) studies have calculated GHG emissions from oil sands extraction, upgrading, and refining pathways. The results from these studies vary considerably. This paper reviews factors affecting energy consumption and GHG emissions from oil sands extraction. It then uses publicly available data to analyze the assumptions made in the LCA models to better understand the causes of variability in emissions estimates. It is found that the variation in oil sands GHG estimates is due to a variety of causes. In approximate order of importance, these are scope of modeling and choice of projects analyzed (e.g., specific projects vs industry averages); differences in assumed energy intensities of extraction and upgrading; differences in the fuel mix assumptions; treatment of secondary noncombustion emissions sources, such as venting, flaring, and fugitive emissions; and treatment of ecological emissions sources, such as land-use change-associated emissions. The GHGenius model is recommended as the LCA model that is most congruent with reported industry average data. GHGenius also has the most comprehensive system boundaries. Last, remaining uncertainties and future research needs are discussed.

  10. Variability of fire carbon emissions in equatorial Asia and its nonlinear sensitivity to El Niño

    Science.gov (United States)

    Yin, Yi; Ciais, Philippe; Chevallier, Frederic; Werf, Guido R.; Fanin, Thierry; Broquet, Gregoire; Boesch, Hartmut; Cozic, Anne; Hauglustaine, Didier; Szopa, Sophie; Wang, Yilong

    2016-10-01

    The large peatland carbon stocks in the land use change-affected areas of equatorial Asia are vulnerable to fire. Combining satellite observations of active fire, burned area, and atmospheric concentrations of combustion tracers with a Bayesian inversion, we estimated the amount and variability of fire carbon emissions in equatorial Asia over the period 1997-2015. Emissions in 2015 were of 0.51 ± 0.17 Pg carbon—less than half of the emissions from the previous 1997 extreme El Niño, explained by a less acute water deficit. Fire severity could be empirically hindcasted from the cumulative water deficit with a lead time of 1 to 2 months. Based on CMIP5 climate projections and an exponential empirical relationship found between fire carbon emissions and water deficit, we infer a total fire carbon loss ranging from 12 to 25 Pg by 2100 which is a significant positive feedback to climate warming.

  11. Regional Variability and Uncertainty of Electric Vehicle Life Cycle CO₂ Emissions across the United States.

    Science.gov (United States)

    Tamayao, Mili-Ann M; Michalek, Jeremy J; Hendrickson, Chris; Azevedo, Inês M L

    2015-07-21

    We characterize regionally specific life cycle CO2 emissions per mile traveled for plug-in hybrid electric vehicles (PHEVs) and battery electric vehicles (BEVs) across the United States under alternative assumptions for regional electricity emission factors, regional boundaries, and charging schemes. We find that estimates based on marginal vs average grid emission factors differ by as much as 50% (using National Electricity Reliability Commission (NERC) regional boundaries). Use of state boundaries versus NERC region boundaries results in estimates that differ by as much as 120% for the same location (using average emission factors). We argue that consumption-based marginal emission factors are conceptually appropriate for evaluating the emissions implications of policies that increase electric vehicle sales or use in a region. We also examine generation-based marginal emission factors to assess robustness. Using these two estimates of NERC region marginal emission factors, we find the following: (1) delayed charging (i.e., starting at midnight) leads to higher emissions in most cases due largely to increased coal in the marginal generation mix at night; (2) the Chevrolet Volt has higher expected life cycle emissions than the Toyota Prius hybrid electric vehicle (the most efficient U.S. gasoline vehicle) across the U.S. in nearly all scenarios; (3) the Nissan Leaf BEV has lower life cycle emissions than the Prius in the western U.S. and in Texas, but the Prius has lower emissions in the northern Midwest regardless of assumed charging scheme and marginal emissions estimation method; (4) in other regions the lowest emitting vehicle depends on charge timing and emission factor estimation assumptions.

  12. Detection of millimeter-wavelength intraday variability in polarized emission from S5 0716+714

    Science.gov (United States)

    Lee, Jee Won; Lee, Sang-Sung; Kang, Sincheol; Byun, Do-Young; Kim, Sungsoo S.

    2016-08-01

    We report the detection of millimeter-wavelength intraday variability in polarized emission from S5 0716+714 based on multifrequency polarization observations using the Korean VLBI Network (KVN) radio telescopes. The observations were conducted on November 7, 2013 at 22, 43, and 86 GHz in dual polarization using two 21 m radio telescopes belonging to KVN Yonsei and Ulsan. We found significant variations in the degree of linear polarization at 86 GHz and in polarization angle at 43 and 86 GHz during ~10 h. We measured mean flux densities of 2.8 Jy, 2.8 Jy, and 2.7 Jy at 22, 43, and 86 GHz, respectively, with a flux modulation index ranging from 1.5% to 7.2% at the frequencies. The spectrum of the source is quite flat with spectral indices of -0.07 to 0.07 at 22-43 GHz and -0.23 to 0.04 at 43-86 GHz. The measured degree of the linear polarization ranges from 2.3% to 3.3% at 22 GHz from 0.9% to 2.2% at 43 GHz and from 0.4% to 4.0% at 86 GHz, yielding prominent variations at 86 GHz over 4-5 h. The linear polarization angle is in the range of 4° to 12° at 22 GHz, -39° to 81° at 43 GHz, and 66° to 119° at 86 GHz with a maximum rotation of 110° at 43 GHz over ~4 h. We estimated the Faraday rotation measures (RM) ranging from -9200 to 6300 rad m-2 between 22 and 43 GHz, and from -71 000 to 7300 rad m-2 between 43 and 86 GHz, respectively. The frequency dependency of RM was investigated, yielding a mean power-law index, a, of 2.0. This implies that the polarized emission from S5 0716+714 at 22-86 GHz moves through a Faraday screen in or near the jet of the source.

  13. Relationship of goat milk flow emission variables with milking routine, milking parameters, milking machine characteristics and goat physiology.

    Science.gov (United States)

    Romero, G; Panzalis, R; Ruegg, P

    2017-11-01

    The aim of this paper was to study the relationship between milk flow emission variables recorded during milking of dairy goats with variables related to milking routine, goat physiology, milking parameters and milking machine characteristics, to determine the variables affecting milking performance and help the goat industry pinpoint farm and milking practices that improve milking performance. In total, 19 farms were visited once during the evening milking. Milking parameters (vacuum level (VL), pulsation ratio and pulsation rate, vacuum drop), milk emission flow variables (milking time, milk yield, maximum milk flow (MMF), average milk flow (AVMF), time until 500 g/min milk flow is established (TS500)), doe characteristics of 8 to 10 goats/farm (breed, days in milk and parity), milking practices (overmilking, overstripping, pre-lag time) and milking machine characteristics (line height, presence of claw) were recorded on every farm. The relationships between recorded variables and farm were analysed by a one-way ANOVA analysis. The relationships of milk yield, MMF, milking time and TS500 with goat physiology, milking routine, milking parameters and milking machine design were analysed using a linear mixed model, considering the farm as the random effect. Farm was significant (Pvariables. Milk emission flow variables were similar to those recommended in scientific studies. Milking parameters were adequate in most of the farms, being similar to those recommended in scientific studies. Few milking parameters and milking machine characteristics affected the tested variables: average vacuum level only showed tendency on MMF, and milk pipeline height on TS500. Milk yield (MY) was mainly affected by parity, as the interaction of days in milk with parity was also significant. Milking time was mainly affected by milk yield and breed. Also significant were parity, the interaction of days in milk with parity and overstripping, whereas overmilking showed a slight tendency

  14. Diurnal and seasonal variability of gasoline-related volatile organic compound emissions in Riverside, California.

    Science.gov (United States)

    Gentner, Drew R; Harley, Robert A; Miller, Angela M; Goldstein, Allen H

    2009-06-15

    On- and off-road mobile sources are the dominant contributors to urban anthropogenic volatile organic compound (AVOC) emissions. Analyses of gasoline samples from California for both summer and winter indicate significant differences in liquid fuel and vapor chemical composition due to intentional seasonal adjustments. Ambient concentrations of 55 VOCs were measured via in situ gas chromatography in the 2005 Study of Organic Aerosols at Riverside (SOAR) during both summer and fall. A chemical mass balance analysis was used to differentiate vapor pressure-driven VOC emissions from other motor vehicle-related emissions such as tailpipe exhaust. Overall, fuel vapor emissions accounted for 31 +/- 2% of gasoline-related VOC in Riverside; California's emission factor model similarly estimates 31% of gasoline-related VOC emissions are fuel vapor. The diurnal pattern of vapor pressure-driven VOC source contributions is relatively stable around 10 microg/m3, while whole gasoline (i.e., tailpipe) contributions peak at approximately 60 microg/m3 during the morning commute. There is no peak in whole gasoline source contributions during the afternoon, due to rapid dilution associated with high mixing heights and wind speeds in the Riverside area. The relationship between estimated gasoline-related VOC and observed carbon monoxide concentrations in this study is similar to California's 2005 emission inventory; we calculated a VOC to CO mass ratio of 0.086 +/- 0.006 (95% CI) compared to 0.097 in the emission inventory for all gasoline-related sources.

  15. Variability of BVOC emissions from a Mediterranean mixed forest in southern France with a focus on Quercus pubescens

    Science.gov (United States)

    Genard-Zielinski, A.-C.; Boissard, C.; Fernandez, C.; Kalogridis, C.; Lathière, J.; Gros, V.; Bonnaire, N.; Ormeño, E.

    2015-01-01

    We aimed at quantifying biogenic volatile organic compound (BVOC) emissions in June from three Mediterranean species located at the O3HP site (southern France): Quercus pubescens, Acer monspessulanum and C. coggygria (for isoprene only). As Q. pubescens was shown to be the main BVOC emitter with isoprene representing ≈ 99% of the carbon emitted as BVOC, we mainly focused on this species. C. coggygria was found to be a non-isoprene emitter (no other BVOCs were investigated). To fully understand both the canopy effect on Q. pubescens isoprene emissions and the inter-individual variability (tree to tree and within canopy), diurnal variations of isoprene were investigated from nine branches (seven branches located to the top of canopy at ≈ 4 m above ground level (a.g.l.), and two inside the canopy at ≈ 2 m a.g.l.). The Q. pubescens daily mean isoprene emission rate (ERd) fluctuated between 23 and 98 μgC gDM-1 h-1. Q. pubescens daily mean net assimilation (Pn) ranged between 5.4 and 13.8, and 2.8 and 6.4 μmol CO2 m-2 s-1 for sunlit and shaded branches respectively. Both ERd and isoprene emission factors (Is), assessed according to Guenther et al. (1993) algorithm, varied by a factor of 4.3 among the sunlit branches. While sunlit branches ERd was clearly higher than for shaded branches, there was a non-significant variability of Is (59 to 77 μgC gDM-1 h-1). Diurnal variations of isoprene emission rates (ERs) for sunlit branches were also investigated. ERs were detected at dawn 2 h after Pn became positive and were mostly exponentially dependent on Pn. Diurnal variations of ERs were not equally well described throughout the day by temperature (CT) and light (CL) parameters according to G93 algorithm. Temperature had more impact than photosynthetically active radiation (PAR) on the morning emissions increase, and ER was no longer correlated to CL × CT between solar noon (maximum ER) and mid-afternoon, possibly due to thermal stress of the plant. A comparison

  16. Modelo de cálculo de las emisiones difusas de gases de efecto invernadero procedentes del transporte. Análisis según variables de diseño urbanístico/Calculation model for greenhouse gases diffuse emissions from transport. Analysis by urban design variables

    National Research Council Canada - National Science Library

    Sergio Zubelzu-Mínguez; Alfonso Isidro López-Díaz; Miguel Ángel Gutiérrez-García; Fernando Blanco-Silva

    2014-01-01

    .... Emissions from road traffic join outstandingly in diffuse emissions. This paper studies these kind of emissions related to urban planning and proposes a model to calculate emissions, by using variables such as land use, vial length or edificability...

  17. Climatic variability, hydrologic anomaly, and methane emission can turn productive freshwater marshes into net carbon sources.

    Science.gov (United States)

    Chu, Housen; Gottgens, Johan F; Chen, Jiquan; Sun, Ge; Desai, Ankur R; Ouyang, Zutao; Shao, Changliang; Czajkowski, Kevin

    2015-03-01

    Freshwater marshes are well-known for their ecological functions in carbon sequestration, but complete carbon budgets that include both methane (CH4 ) and lateral carbon fluxes for these ecosystems are rarely available. To the best of our knowledge, this is the first full carbon balance for a freshwater marsh where vertical gaseous [carbon dioxide (CO2 ) and CH4 ] and lateral hydrologic fluxes (dissolved and particulate organic carbon) have been simultaneously measured for multiple years (2011-2013). Carbon accumulation in the sediments suggested that the marsh was a long-term carbon sink and accumulated ~96.9 ± 10.3 (±95% CI) g C m(-2)  yr(-1) during the last ~50 years. However, abnormal climate conditions in the last 3 years turned the marsh to a source of carbon (42.7 ± 23.4 g C m(-2)  yr(-1) ). Gross ecosystem production and ecosystem respiration were the two largest fluxes in the annual carbon budget. Yet, these two fluxes compensated each other to a large extent and led to the marsh being a CO2 sink in 2011 (-78.8 ± 33.6 g C m(-2)  yr(-1) ), near CO2 -neutral in 2012 (29.7 ± 37.2 g C m(-2)  yr(-1) ), and a CO2 source in 2013 (92.9 ± 28.0 g C m(-2)  yr(-1) ). The CH4 emission was consistently high with a three-year average of 50.8 ± 1.0 g C m(-2)  yr(-1) . Considerable hydrologic carbon flowed laterally both into and out of the marsh (108.3 ± 5.4 and 86.2 ± 10.5 g C m(-2)  yr(-1) , respectively). In total, hydrologic carbon fluxes contributed ~23 ± 13 g C m(-2)  yr(-1) to the three-year carbon budget. Our findings highlight the importance of lateral hydrologic inflows/outflows in wetland carbon budgets, especially in those characterized by a flow-through hydrologic regime. In addition, different carbon fluxes responded unequally to climate variability/anomalies and, thus, the total carbon budgets may vary drastically among years. © 2014 John Wiley & Sons Ltd.

  18. DURACON - Variable Emissivity Broadband Coatings for Liquid Propellant Rocket Nozzles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The need exists for a fast drying, robust, low gloss, black, high emissivity coating that can be applied easily on aircraft rocket nozzles and nozzle extensions....

  19. Inter-annual variability in fossil-fuel CO2 emissions due to temperature anomalies

    Science.gov (United States)

    Bréon, F.-M.; Boucher, O.; Brender, P.

    2017-07-01

    It is well known that short-term (i.e. interannual) variations in fossil-fuel CO2 emissions are closely related to the evolution of the national economies. Nevertheless, a fraction of the CO2 emissions are linked to domestic and business heating and cooling, which can be expected to be related to the meteorology, independently of the economy. Here, we analyse whether the signature of the inter-annual temperature anomalies is discernible in the time series of CO2 emissions at the country scale. Our analysis shows that, for many countries, there is a clear positive correlation between a heating-degree-person index and the component of the CO2 emissions that is not explained by the economy as quantified by the gross domestic product (GDP). Similarly, several countries show a positive correlation between a cooling-degree-person (CDP) index and CO2 emissions. The slope of the linear relationship for heating is on the order of 0.5-1 kg CO2 (degree-day-person)-1 but with significant country-to-country variations. A similar relationship for cooling shows even greater diversity. We further show that the inter-annual climate anomalies have a small but significant impact on the annual growth rate of CO2 emissions, both at the national and global scale. Such a meteorological effect was a significant contribution to the rather small and unexpected global emission growth rate in 2014 while its contribution to the near zero emission growth in 2015 was insignificant.

  20. Variability in the primary emissions and secondary gas and particle formation from vehicles using bio-ethanol mixtures.

    Science.gov (United States)

    Gramsch, E; Papapostolou, V; Reyes, F; Vásquez, Y; Castillo, M; Oyola, P; López, G; Cádiz, A; Ferguson, S; Wolfson, M; Lawrence, J; Koutrakis, P

    2017-10-11

    Bioethanol for use in vehicles is becoming a substantial part of global energy infrastructure because it is renewable and some emissions are reduced. Carbon monoxide (CO) emissions and total hydrocarbons (THC) are reduced but there is still controversy regarding emissions of nitrogen oxides (NOx), aldehydes and ethanol, this may be a concern because all these compounds are precursors of ozone and secondary organic aerosol (SOA). The amount of emissions depends on the ethanol content, but also may depend on the engine quality and ethanol origin. Thus, a photochemical chamber was used to study secondary gas and aerosol formation from two flex-fueled vehicles using different ethanol blends in gasoline. One vehicle and the fuel used were made in USA and the others were made in Brazil. Primary emissions of total hydrocarbons (THC), CO, carbon dioxide (CO2), and non-methane hydrocarbons (NMHC) from both vehicles decreased as the amount of ethanol in gasoline increased. NOx emissions in the American and Brazilian car decreased with ethanol content. However, emissions of THC, CO and NOx from the Brazilian car were markedly higher than those from the U. S. car showing high variability between vehicle technologies. In the Brazilian car, formation of secondary nitrogen dioxide (NO2) and ozone (O3) was lower for higher ethanol content in the fuel. In the American car, NO2 and O3 had a small increase. Secondary particle (PM) formation in the chamber decreased for both vehicles as the fraction of ethanol in fuel increased, consistent with previous studies. Secondary to primary PM ratios for pure gasoline is 11, also consistent with previous studies. In addition, the time required to form secondary PM is longer for higher ethanol blends. These results indicate that using higher ethanol blends may have a positive impact on air quality. The use of bio-ethanol can significantly reduce petroleum use and greenhouse gas emissions worldwide. Given the extent of its use, it is important

  1. Wet-season spatial variability of N2O emissions from a tea field in subtropical central China

    Science.gov (United States)

    Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

    2015-01-01

    Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability of N2O emissions from a red-soil tea field in Hunan province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10-10.30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt), total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r=0.57-0.71, pobtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern (e.g., tea row transects in the present study) must be included in spatial interpolation. Additionally, compared with other kriging approaches, the cokriging prediction approach showed great advantages in being easily deployed, and more importantly providing accurate regional estimation of N2O emissions from tea-planted soils.

  2. Wet-season spatial variability in N2O emissions from a tea field in subtropical central China

    Science.gov (United States)

    Fu, X.; Liu, X.; Li, Y.; Shen, J.; Wang, Y.; Zou, G.; Li, H.; Song, L.; Wu, J.

    2015-06-01

    Tea fields emit large amounts of nitrous oxide (N2O) to the atmosphere. Obtaining accurate estimations of N2O emissions from tea-planted soils is challenging due to strong spatial variability. We examined the spatial variability in N2O emissions from a red-soil tea field in Hunan Province, China, on 22 April 2012 (in a wet season) using 147 static mini chambers approximately regular gridded in a 4.0 ha tea field. The N2O fluxes for a 30 min snapshot (10:00-10:30 a.m.) ranged from -1.73 to 1659.11 g N ha-1 d-1 and were positively skewed with an average flux of 102.24 g N ha-1 d-1. The N2O flux data were transformed to a normal distribution by using a logit function. The geostatistical analyses of our data indicated that the logit-transformed N2O fluxes (FLUX30t) exhibited strong spatial autocorrelation, which was characterized by an exponential semivariogram model with an effective range of 25.2 m. As observed in the wet season, the logit-transformed soil ammonium-N (NH4Nt), soil nitrate-N (NO3Nt), soil organic carbon (SOCt) and total soil nitrogen (TSNt) were all found to be significantly correlated with FLUX30t (r = 0.57-0.71, p obtained during the wet season. Our findings suggested that to accurately estimate the total N2O emissions over a region, the environmental variables (e.g., soil properties) and the current land use pattern (e.g., tea row transects in the present study) must be included in spatial interpolation. Additionally, compared with other kriging approaches, the cokriging prediction approach showed great advantages in being easily deployed and, more importantly, providing accurate regional estimation of N2O emissions from tea-planted soils.

  3. Variability of N{sub 2}O emissions during the production of poplar and rye

    Energy Technology Data Exchange (ETDEWEB)

    Kern, Juergen; Hellebrand, Hans Juergen; Scholz, Volkhard [ATB Potsdam (Germany)], E-mail: jkern@atb-potsdam.de

    2008-07-01

    The emission of N{sub 2}O from the soil has a significant impact on the greenhouse gas balance of energy crops. Soil type, temperature, precipitation, tillage practice and level of fertilization may affect the source strength of N{sub 2}O emissions and fertilizer-induced N{sub 2}O emissions. The N{sub 2}O-fluxes from different sites of an experimental field were measured by the flux chamber method over a period of four years (2003-2006). Poplar and rye as one perennial and one annual crop were fertilized at levels of 0 kg N ha{sup -1} yr{sup -1}, 75 kg N ha{sup -1} yr{sup -1} and 150 kg N ha{sup -1} yr{sup -1}. Enhanced N{sub 2}O emission spots with maxima of up to 1653 {mu}g N{sub 2}O m{sup -2} h{sup -1} were observed at fertilized sites for several weeks. The emissions ranged between 0.4 kg N{sub 2}O-N ha{sup -1} yr{sup -1} and 2.7 kg N{sub 2}O-N ha{sup -1} yr{sup -1} depending on fertilization level, crop variety and year. The mean conversion factor was 2.1% for poplar and 0.9% for rye. The CO{sub 2}-advantage of energy crops is reduced by N{sub 2}O emissions by up to 10%. (author)

  4. High Turndown Ratio, High Delta-Emittance, Variable Emissivity Electrochromics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Among thermal control methods, variable-emittance materials remain the most promising for addressing deficiencies of current systems (mechanical louvers, loop heat...

  5. Iwamoto-Harada coalescence/pickup model for cluster emission: state density approach including angular momentum variables

    Directory of Open Access Journals (Sweden)

    Běták Emil

    2014-04-01

    Full Text Available For low-energy nuclear reactions well above the resonance region, but still below the pion threshold, statistical pre-equilibrium models (e.g., the exciton and the hybrid ones are a frequent tool for analysis of energy spectra and the cross sections of cluster emission. For α’s, two essentially distinct approaches are popular, namely the preformed one and the different versions of coalescence approaches, whereas only the latter group of models can be used for other types of cluster ejectiles. The original Iwamoto-Harada model of pre-equilibrium cluster emission was formulated using the overlap of the cluster and its constituent nucleons in momentum space. Transforming it into level or state densities is not a straigthforward task; however, physically the same model was presented at a conference on reaction models five years earlier. At that time, only the densities without spin were used. The introduction of spin variables into the exciton model enabled detailed calculation of the γ emission and its competition with nucleon channels, and – at the same time – it stimulated further developments of the model. However – to the best of our knowledge – no spin formulation has been presented for cluster emission till recently, when the first attempts have been reported, but restricted to the first emission only. We have updated this effort now and we are able to handle (using the same simplifications as in our previous work pre-equilibrium cluster emission with spin including all nuclei in the reaction chain.

  6. Spatiotemporal variability of biogenic terpenoid emissions in Pearl River Delta, China, with high-resolution land-cover and meteorological data

    Science.gov (United States)

    Wang, Xuemei; Situ, Shuping; Guenther, Alex; Chen, Fei; Wu, Zhiyong; Xia, Beicheng; Wang, Tijian

    2011-04-01

    This study intended to provide 4-km gridded, hourly, year-long, regional estimates of terpenoid emissions in the Pearl River Delta (PRD), China. It combined Thematic Mapper images and local-survey data to characterize plant functional types, and used observed emission potential of biogenic volatile organic compounds (BVOC) from local plant species and high-resolution meteorological outputs from the MM5 model to constrain the MEGAN BVOC-emission model. The estimated annual emissions for isoprene, monoterpene and sesquiterpene are 95.55 × 106 kg C, 117.35 × 106 kg C and 9.77 × 106 kg C, respectively. The results show strong variabilities of terpenoid emissions spanning diurnal and seasonal time scales, which are mainly distributed in the remote areas (with more vegetation and less economic development) in PRD. Using MODIS PFTs data reduced terpenoid emissions by 27% in remote areas. Using MEGAN-model default emission factors led to a 24% increase in BVOC emission. The model errors of temperature and radiation in MM5 output were used to assess impacts of uncertainties in meteorological forcing on emissions: increasing (decreasing) temperature and downward shortwave radiation produces more (less) terpenoid emissions for July and January. Strong temporal variability of terpenoid emissions leads to enhanced ozone formation during midday in rural areas where the anthropogenic VOC emissions are limited.

  7. Spatial variability in nitrous oxide and methane emissions from beef cattle feedyard pen surfaces

    Science.gov (United States)

    Greenhouse gas emissions from beef cattle feedlots include enteric carbon dioxide and methane, and manure-derived methane, nitrous oxide and carbon dioxide. Enteric methane comprises the largest portion of the greenhouse gas footprint of beef cattle feedyards. For the manure component, methane is th...

  8. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    NARCIS (Netherlands)

    Amato, F.; Schaap, M.; Denier van der Gon, H.A.C.; Pandolfi, M.; Alastuey, A.; Keuken, M.; Querol, X.

    2013-01-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well

  9. RE Data Explorer: Informing Variable Renewable Energy Grid Integration for Low Emission Development

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Sarah L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-08

    The RE Data Explorer, developed by the National Renewable Energy Laboratory, is an innovative web-based analysis tool that utilizes geospatial and spatiotemporal renewable energy data to visualize, execute, and support analysis of renewable energy potential under various user-defined scenarios. This analysis can inform high-level prospecting, integrated planning, and policy making to enable low emission development.

  10. Temporal variability of methane fluxes in West Siberian taiga bogs and its implications for estimating regional methane emission

    Science.gov (United States)

    Sabrekov, Alexander; Ilyasov, Danil; Terentieva, Irina; Glagolev, Mikhail; Maksyutov, Shamil

    2017-04-01

    The West Siberia Lowland (WSL) is the biggest peatland area in Eurasia and is situated in the high latitudes experiencing enhanced rate of climate change. During 2015-16 summer periods, seasonal measurements of methane emission were made at the field station «Mukhrino» in the WSL middle taiga zone. The study was made at 3 wetland ecosystem types covering 80% of the taiga wetland area: i) waterlogged hollows or depressed areas with water level above the moss surface, ii) oligotrophic hollows or depressed parts of bogs with water level beneath the moss surface, iii) forested bogs with dwarf shrubs-sphagnum vegetation. Seven series of measurements were made by a static chamber method in 2016 and four series - in 2015. In 2015, we observed non-typical weather conditions including early dry spring and short cold rainy summer. Oppositely, weather conditions in 2016 were closer to average long-term with warmer drier summer. Significant difference between these years allowed analyzing the temporal variability and its sources. Average methane flux rates from forested bogs were 0.57 mgCH4/m2/h in 2016 and 0.33 mgCH4/m2/h in 2015. Seasonal dynamic during both years had similar concave downward shape. The highest fluxes were observed in June and were corresponded to the highest WTL, the main limiting factor of emission from forested bogs. The lowest fluxes in July were related to the low WTL combining with the highest temperature of upper methanotrophy layer. Average methane flux rates from oligotrophic hollows were 7.18 mgCH4/m2/h in 2016 and 4.28 mgCH4/m2/h in 2015. Seasonal dynamic of methane emission was indistinct in 2015. On the contrary, in 2016 it had regular seasonal pattern with peak emissions in July, which were four times higher than in 2015. WTL was not the limiting factor for CH4 emission from oligotrophic hollows, because even in the driest ones it was only 10 cm below the surface. Thus, the difference between peak emissions in 2015 and 2016 was mainly related

  11. Temporal and spatial variability of Icelandic dust emissions and atmospheric transport

    Science.gov (United States)

    Groot Zwaaftink, Christine D.; Arnalds, Ólafur; Dagsson-Waldhauserova, Pavla; Eckhardt, Sabine; Prospero, Joseph M.; Stohl, Andreas

    2017-09-01

    Icelandic dust sources are known to be highly active, yet there exist few model simulations of Icelandic dust that could be used to assess its impacts on the environment. We here present estimates of dust emission and transport in Iceland over 27 years (1990-2016) based on FLEXDUST and FLEXPART simulations and meteorological re-analysis data. Simulations for the year 2012 based on high-resolution operational meteorological analyses are used for model evaluation based on PM2. 5 and PM10 observations in Iceland. For stations in Reykjavik, we find that the spring period is well predicted by the model, while dust events in late fall and early winter are overpredicted. Six years of dust concentrations observed at Stórhöfði (Heimaey) show that the model predicts concentrations of the same order of magnitude as observations and timing of modelled and observed dust peaks agrees well. Average annual dust emission is 4.3 ± 0.8 Tg during the 27 years of simulation. Fifty percent of all dust from Iceland is on average emitted in just 25 days of the year, demonstrating the importance of a few strong events for annual total dust emissions. Annual dust emission as well as transport patterns correlate only weakly to the North Atlantic Oscillation. Deposition amounts in remote regions (Svalbard and Greenland) vary from year to year. Only limited dust amounts reach the upper Greenland Ice Sheet, but considerable dust amounts are deposited on Icelandic glaciers and can impact melt rates there. Approximately 34 % of the annual dust emission is deposited in Iceland itself. Most dust (58 %), however, is deposited in the ocean and may strongly influence marine ecosystems.

  12. Temporal and spatial variability of Icelandic dust emissions and atmospheric transport

    Directory of Open Access Journals (Sweden)

    C. D. Groot Zwaaftink

    2017-09-01

    Full Text Available Icelandic dust sources are known to be highly active, yet there exist few model simulations of Icelandic dust that could be used to assess its impacts on the environment. We here present estimates of dust emission and transport in Iceland over 27 years (1990–2016 based on FLEXDUST and FLEXPART simulations and meteorological re-analysis data. Simulations for the year 2012 based on high-resolution operational meteorological analyses are used for model evaluation based on PM2. 5 and PM10 observations in Iceland. For stations in Reykjavik, we find that the spring period is well predicted by the model, while dust events in late fall and early winter are overpredicted. Six years of dust concentrations observed at Stórhöfði (Heimaey show that the model predicts concentrations of the same order of magnitude as observations and timing of modelled and observed dust peaks agrees well. Average annual dust emission is 4.3 ± 0.8 Tg during the 27 years of simulation. Fifty percent of all dust from Iceland is on average emitted in just 25 days of the year, demonstrating the importance of a few strong events for annual total dust emissions. Annual dust emission as well as transport patterns correlate only weakly to the North Atlantic Oscillation. Deposition amounts in remote regions (Svalbard and Greenland vary from year to year. Only limited dust amounts reach the upper Greenland Ice Sheet, but considerable dust amounts are deposited on Icelandic glaciers and can impact melt rates there. Approximately 34 % of the annual dust emission is deposited in Iceland itself. Most dust (58 %, however, is deposited in the ocean and may strongly influence marine ecosystems.

  13. Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

    Science.gov (United States)

    Sabrekov, Aleksandr F.; Runkle, Benjamin R. K.; Glagolev, Mikhail V.; Terentieva, Irina E.; Stepanenko, Victor M.; Kotsyurbenko, Oleg R.; Maksyutov, Shamil S.; Pokrovsky, Oleg S.

    2017-08-01

    Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July-August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m-2 h-1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m-2 h-1 for southern taiga lakes, respectively. Pronounced flux variability was found during measurements on individual lakes, between individual lakes and between zones. To analyze these differences and the influences of environmental controls, we developed a new dynamic process-based model. It shows good performance with emission rates from the southern taiga lakes and poor performance for individual lakes in the middle taiga region. The model shows that, in addition to well-known controls such as temperature, pH and lake depth, there are significant variations in the maximal methane production potential between these climatic zones. In addition, the model shows that variations in gas-filled pore space in lake sediments are capable of controlling the total methane emissions from individual lakes. The CH4 emissions exhibited distinct zonal differences not only in absolute values but also in their probability density functions: the middle taiga lake fluxes were best described by a lognormal distribution while the southern taiga lakes followed a power-law distribution. The latter suggests applicability of self-organized criticality theory for methane emissions from the southern taiga zone, which could help to explain the strong variability within individual lakes.

  14. Variability in methane emissions from West Siberia's shallow boreal lakes on a regional scale and its environmental controls

    Directory of Open Access Journals (Sweden)

    A. F. Sabrekov

    2017-08-01

    Full Text Available Small lakes represent an important source of atmospheric CH4 from northern wetlands. However, spatiotemporal variations in flux magnitudes and the lack of knowledge about their main environmental controls contribute large uncertainty into the global CH4 budget. In this study, we measured methane fluxes from small lakes using chambers and bubble traps. Field investigations were carried out in July–August 2014 within the West Siberian middle and southern taiga zones. The average and median of measured methane chamber fluxes were 0.32 and 0.30 mgCH4 m−2 h−1 for middle taiga lakes and 8.6 and 4.1 mgCH4 m−2 h−1 for southern taiga lakes, respectively. Pronounced flux variability was found during measurements on individual lakes, between individual lakes and between zones. To analyze these differences and the influences of environmental controls, we developed a new dynamic process-based model. It shows good performance with emission rates from the southern taiga lakes and poor performance for individual lakes in the middle taiga region. The model shows that, in addition to well-known controls such as temperature, pH and lake depth, there are significant variations in the maximal methane production potential between these climatic zones. In addition, the model shows that variations in gas-filled pore space in lake sediments are capable of controlling the total methane emissions from individual lakes. The CH4 emissions exhibited distinct zonal differences not only in absolute values but also in their probability density functions: the middle taiga lake fluxes were best described by a lognormal distribution while the southern taiga lakes followed a power-law distribution. The latter suggests applicability of self-organized criticality theory for methane emissions from the southern taiga zone, which could help to explain the strong variability within individual lakes.

  15. High Turndown Ratio, High Delta-Emittance, Variable Emissivity Electrochromics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable-emittance materials are in high demand for applications ranging from manned and unmanned space platforms (e.g. in radiators at the Moon's poles where damage...

  16. Variable Emissivity Electrochromics Using Ionic Electrolytes and Low Solar Absorptance Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In recent work, this firm developed a highly promising, patented variable emittance technology based on electrochromic Conducting Polymers, with: (1) Thin (< 0.2...

  17. Seasonal Variability in Atmospheric Methane Mixing Ratio and Coastal Methane Emission from the Southwest United Kingdom

    Science.gov (United States)

    Yang, Mingxi; Bell, Thomas; Hopkins, Frances; Nightingale, Phil

    2017-04-01

    We report 2+ year observations of atmospheric methane (CH4) mixing ratio and water-to-air CH4 fluxes from the Penlee Point Atmospheric Observatory (PPAO) on the southwest coast of the UK. About 6 km southwest of Plymouth, this coastal site is located at the mouth of the Plymouth Sound, 10 m above mean sea level, and 30 m from the water's edge. Air from the southwest encounters little terrestrial influence and appears to be largely representative of the background North Atlantic. The other wind sectors are affected to a varying degree by natural and anthropogenic terrestrial emissions as well as discharge from the nearby Tamar estuary/Plymouth Sound. Compared to the southwest wind sector, CH4 mixing ratios from terrestrially influenced wind sectors are greater in the mean and also show stronger seasonality (higher in winter than in summer). Novel application of the eddy covariance technique enables a direct and continuous quantification of the water-to-air CH4 fluxes. CH4 emissions from this region exceed predicted CH4 fluxes over the open ocean but are less than estimates from polar regions or freshwater systems. Within the water-facing wind sectors, CH4 emissions are a few times higher when winds are over the Plymouth Sound than when winds are from the southwest, suggesting a source from riverine outflow. Long-term measurements of CH4 fluxes allow us to examine the dependence on wind speed, tide, and water temperature.

  18. Performance and exhaust emission characteristics of variable compression ratio diesel engine fuelled with esters of crude rice bran oil.

    Science.gov (United States)

    Vasudeva, Mohit; Sharma, Sumeet; Mohapatra, S K; Kundu, Krishnendu

    2016-01-01

    As a substitute to petroleum-derived diesel, biodiesel has high potential as a renewable and environment friendly energy source. For petroleum importing countries the choice of feedstock for biodiesel production within the geographical region is a major influential factor. Crude rice bran oil is found to be good and viable feedstock for biodiesel production. A two step esterification is carried out for higher free fatty acid crude rice bran oil. Blends of 10, 20 and 40 % by vol. crude rice bran biodiesel are tested in a variable compression ratio diesel engine at compression ratio 15, 16, 17 and 18. Engine performance and exhaust emission parameters are examined. Cylinder pressure-crank angle variation is also plotted. The increase in compression ratio from 15 to 18 resulted in 18.6 % decrease in brake specific fuel consumption and 14.66 % increase in brake thermal efficiency on an average. Cylinder pressure increases by 15 % when compression ratio is increased. Carbon monoxide emission decreased by 22.27 %, hydrocarbon decreased by 38.4 %, carbon dioxide increased by 17.43 % and oxides of nitrogen as NOx emission increased by 22.76 % on an average when compression ratio is increased from 15 to 18. The blends of crude rice bran biodiesel show better results than diesel with increase in compression ratio.

  19. Spatial and Temporal Variability of Freeze back of Polygonal Tundra and Implications for Green House gas Emissions

    Science.gov (United States)

    Langer, M.; Westermann, S.; Piel, K.; Muster, S.; Abnizova, A.; Boike, J.

    2010-12-01

    Observations indicate a massive warming in the Arctic during the last decades and climate models predict an even increased warming trend in the following century. The changing climate conditions most likely degrade permafrost, which is often related to the formation of thermokarst lakes. The relevance of such larger water bodies for the emission of green house gases (GHG) in high latitude wetlands has been demonstrated by Walter et al. 2006. We investigate the physical processes and emission of GHG of small and shallow water bodies at our research site in the Lena Delta, Siberia. The polygonal land cover is characterized by thermokarst lakes (10%), wet depressed polygonal centers (31%), polygonal ponds (6%) and dry rims (53%). Using measured energy balance components, we compare the physical processes between the polygonal centers and ponds during 2007-2008. The physical measurements reveal a high inter-annual variability of time required for freezing of the ponds which can differ up to several months, whereas spring thawing appears to be a more constant process. The observed temporal variability is closely related to the snow cover evolution and the cloudiness, which both significantly alter the surface energy balance during the winter season. Different lengths of unfrozen periods of sediment and water favour microbial activity, which in turn could lead to inter-annual variability of green house gas production, and possibly to significant differences in green house gas emissions during the melt of ice cover. Due to the observed sensitivity of refreezing, future work on microbial activity and the energy balance of small water bodies in the arctic is highly desirable for understanding the emission potential of green house gases of permafrost regions. M Langer, S Westermann, S Muster, K Piel, J Boike. Permafrost and surface energy balance of a polygonal tundra site in Northern Siberia. Part 2: Winter. The Cryosphere. In review. KM Walter, SA Zimov, JP Chanton, D

  20. Experimental investigation on cyclic variability, engine performance and exhaust emissions in a diesel engine using alcohol-diesel fuel blends

    Directory of Open Access Journals (Sweden)

    Gurgen Samet

    2017-01-01

    Full Text Available This paper investigates the impacts of using n-butanol-diesel fuel and ethanol-diesel fuel blends on engine performance, exhaust emission, and cycle-by-cycle variation in a Diesel engine. The engine was operated at two different engine speed and full load condition with pure diesel fuel, 5% and 10% (by vol. ethanol and n-butanol fuel blends. The coefficient of variation of indicated mean effective pressure was used to evaluate the cyclic variability of n-butanol-diesel fuel and ethanol-diesel fuel blends. The results obtained in this study showed that effective efficiency and brake specific fuel consumption generally increased with the use of the n-butanol-diesel fuel or ethanol-diesel fuel blends with respect to that of the neat diesel fuel. The addition of ethanol or n-butanol to diesel fuel caused a decrement in CO and NOx emissions. Also, the results indicated that cycle-by-cycle variation has an increasing trend with the increase of alcohol-diesel blending ratio for all engine speed. An increase in cyclic variability of alcohol-diesel fuel blends at low engine speed is higher than that of high engine speed.

  1. How many replicate tests do I need?$-$ Variability of cookstove performance and emissions has implications for obtaining useful results

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yungang [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Sohn, Michael D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Gadgil, Ashok J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; Wang, Yilun [ISO Innovative Analytics San Francisco, CA (United States); Lask, Kathleen M. [Univ. of California, Berkeley, CA (United States). College of Engineering Applied Science and Technology Program; Kirchstetter, Thomas W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division

    2013-02-01

    Almost half of the world’s population still cooks on biomass cookstoves of poor efficiency and primitive design, such as three stone fires (TSF). Emissions from biomass cookstoves contribute to adverse health effects and climate change. A number of “improved cookstoves” with higher energy efficiency and lower emissions have been designed and promoted across the world. During the design development, and for selection of a stove for dissemination, the stove performance and emissions are commonly evaluated, communicated and compared using the arithmetic average of replicate tests made using a standardized laboratory-based test, commonly the water boiling test (WBT). However, published literature shows different WBT results reported from different laboratories for the same stove technology. Also, there is no agreement in the literature on how many replicate tests should be performed to ensure “significance” in the reported average performance. This matter has not received attention in the rapidly growing literature on stoves, and yet is crucial for estimating and communicating the performance of a stove, and for comparing the performance between stoves. We present results of statistical analyses using data from a number of replicate tests of performance and emission of the Berkeley-Darfur Stove (BDS) and the TSF under well-controlled laboratory conditions. We observed moderate variability in the test results for the TSF and BDS when measuring several characteristics. Here we focus on two as illustrative: time-to-boil and PM2.5 (particulate matter less than or equal to 2.5 micrometers in diameter) emissions. We demonstrate that interpretation of the results comparing these stoves could be misleading if only a small number of replicates had been conducted. We then describe a practical approach, useful to both stove testers and designers, to assess the number of replicates needed to obtain useful data. Caution should be exercised in attaching high credibility to

  2. Monitoring variables affecting positron emission tomography measurements of cerebral blood flow in anaesthetized pigs

    DEFF Research Database (Denmark)

    Alstrup, Aage Kristian Olsen; Zois, Nora Elisabeth; Simonsen, Mette

    female pigs. Results: We found that low blood pH, high arterial carbon dioxide tension (PaCO2), high heart rate, high body temperature and long anaesthesia time are associated with high CBF in anaesthetized pigs. No associations were noted between CBF and low arterial oxygen tension, haematocrit......, systolic and diastolic blood pressure. Conclusions: Our observations indicate that monitoring of pH, PaCO2, heart rate and body temperature are crucial for maintaining stable levels of CBF and thus optimizing PET imaging of molecular mechanisms in the brain of living pig. Furtermore, anaesthesia length......Background: Positron emission tomography (PET) imaging of anaesthetised pig brains is a useful tool in neuroscience. Stable cerebral blood flow (CBF) is essential for PET, since variations can affect the kinetics of several radiotracers. However, the impact of physiological factors regulating CBF...

  3. Environmental and vegetation controls on the spatial variability of CH4emission from wet-sedge and tussock tundra ecosystems in the Arctic.

    Science.gov (United States)

    McEwing, Katherine Rose; Fisher, James Paul; Zona, Donatella

    Despite multiple studies investigating the environmental controls on CH 4 fluxes from arctic tundra ecosystems, the high spatial variability of CH 4 emissions is not fully understood. This makes the upscaling of CH 4 fluxes from plot to regional scale, particularly challenging. The goal of this study is to refine our knowledge of the spatial variability and controls on CH 4 emission from tundra ecosystems. CH 4 fluxes were measured in four sites across a variety of wet-sedge and tussock tundra ecosystems in Alaska using chambers and a Los Gatos CO 2 and CH 4 gas analyser. All sites were found to be sources of CH 4 , with northern sites (in Barrow) showing similar CH 4 emission rates to the southernmost site (ca. 300 km south, Ivotuk). Gross primary productivity (GPP), water level and soil temperature were the most important environmental controls on CH 4 emission. Greater vascular plant cover was linked with higher CH 4 emission, but this increased emission with increased vascular plant cover was much higher (86 %) in the drier sites, than the wettest sites (30 %), suggesting that transport and/or substrate availability were crucial limiting factors for CH 4 emission in these tundra ecosystems. Overall, this study provides an increased understanding of the fine scale spatial controls on CH 4 flux, in particular the key role that plant cover and GPP play in enhancing CH 4 emissions from tundra soils.

  4. THE SMARTS MULTI-EPOCH OPTICAL SPECTROSCOPY ATLAS (SaMOSA): AN ANALYSIS OF EMISSION LINE VARIABILITY IN SOUTHERN HEMISPHERE FERMI BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Isler, Jedidah C. [Chancellor’s Faculty Fellow, Syracuse University, Department of Physics, Syracuse, NY 13244 (United States); Urry, C. M.; Bailyn, C.; Coppi, P.; Brady, M.; MacPherson, E.; Hasan, I.; Buxton, M. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Smith, P. S., E-mail: jcisler@syr.edu [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tuscon, AZ 85721 (United States)

    2015-05-01

    We present multi-epoch optical spectroscopy of seven southern Fermi-monitored blazars from 2008 to 2013 using the Small and Medium Aperture Research Telescope System (SMARTS), with supplemental spectroscopy and polarization data from the Steward Observatory. We find that the emission lines are much less variable than the continuum; four of seven blazars had no detectable emission line variability over the 5 yr observation period. This is consistent with photoionization primarily by an accretion disk, allowing us to use the lines as a probe of disk activity. Comparing optical emission line flux with Fermi γ-ray flux and optical polarized flux, we investigate whether relativistic jet variability is related to the accretion flow. In general, we see no such dependence, suggesting that the jet variability is likely caused by internal processes like turbulence or shock acceleration rather than a variable accretion rate. However, three sources showed statistically significant emission line flares in close temporal proximity to very large Fermi γ-ray flares. While we do not have sufficient emission line data to quantitatively assess their correlation with the γ-ray flux, it appears that in some cases the jet might provide additional photoionizing flux to the broad-line region (BLR), which implies that some γ-rays are produced within the BLR, at least for these large flares.

  5. How to quantify uncertainty and variability in life cycle assessment: the case of greenhouse gas emissions of gas power generation in the US

    Science.gov (United States)

    Hauck, M.; Steinmann, Z. J. N.; Laurenzi, I. J.; Karuppiah, R.; Huijbregts, M. A. J.

    2014-07-01

    This study quantified the contributions of uncertainty and variability to the range of life-cycle greenhouse gas (LCGHG) emissions associated with conventional gas-fired electricity generation in the US. Whereas uncertainty is defined as lack of knowledge and can potentially be reduced by additional research, variability is an inherent characteristic of supply chains and cannot be reduced without physically modifying the system. The life-cycle included four stages: production, processing, transmission and power generation, and utilized a functional unit of 1 kWh of electricity generated at plant. Technological variability requires analyses of life cycles of individual power plants, e.g. combined cycle plants or boilers. Parameter uncertainty was modeled via Monte Carlo simulation. Our approach reveals that technological differences are the predominant cause for the range of LCGHG emissions associated with gas power, primarily due to variability in plant efficiencies. Uncertainties in model parameters played a minor role for 100 year time horizon. Variability in LCGHG emissions was a factor of 1.4 for combined cycle plants, and a factor of 1.3 for simple cycle plants (95% CI, 100 year horizon). The results can be used to assist decision-makers in assessing factors that contribute to LCGHG emissions despite uncertainties in parameters employed to estimate those emissions.

  6. RADIO MONITORING OF THE PERIODICALLY VARIABLE IR SOURCE LRLL 54361: NO DIRECT CORRELATION BETWEEN THE RADIO AND IR EMISSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Forbrich, Jan, E-mail: jan.forbrich@univie.ac.at [University of Vienna, Department of Astrophysics, Türkenschanzstraße 17, A-1180 Vienna (Austria); Rodríguez, Luis F.; Palau, Aina; Zapata, Luis A. [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Muzerolle, James [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gutermuth, Robert A. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2015-11-20

    LRLL 54361 is an infrared source located in the star-forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the results of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of ∼100 AU that smooths out the variability over a period of the order of a year. The average flux density measured in these 2014 observations, 27 ± 5 μJy, is about a factor of two less than that measured about 1.5 years before, 53 ± 11 μJy, suggesting that variability in the radio is present, but over larger timescales than in the IR. We discuss other sources in the field, in particular two infrared/X-ray stars that show rapidly varying gyrosynchrotron emission.

  7. Measuring Solar Doppler Velocities in the He II 30.38 nm Emission Using the EUV Variability Experiment (EVE)

    Science.gov (United States)

    Chamberlin, Phillip Clyde

    2016-01-01

    The EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory has provided unprecedented measurements of the solar EUV irradiance at high temporal cadence with good spectral resolution and range since May 2010. The main purpose of EVE was to connect the Sun to the Earth by providing measurements of the EUV irradianceas a driver for space weather and Living With a Star studies, but after launch the instrument has demonstrated the significance of its measurements in contributing to studies looking at the sources of solar variability for pure solar physics purposes. This paper expands upon previous findings that EVE can in fact measure wavelength shifts during solar eruptive events and therefore provide Doppler velocities for plasma at all temperatures throughout the solar atmosphere from the chromosphere to hot flaring temperatures. This process is not straightforward as EVE was not designed or optimized for these types of measurements. In this paper we describe the many detailed instrumental characterizations needed to eliminate the optical effects in order to provide an absolute baseline for the Doppler shift studies. An example is given of a solar eruption on 7 September 2011 (SOL2011-09-07), associated with an X1.2 flare, where EVE Doppler analysis shows plasma ejected from the Sun in the He II 30.38 nm emission at a velocity of almost 120 km s(exp -1) along the line-of-sight.

  8. Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability

    Science.gov (United States)

    Raiteri, C. M.; Nicastro, F.; Stamerra, A.; Villata, M.; Larionov, V. M.; Blinov, D.; Acosta-Pulido, J. A.; Arévalo, M. J.; Arkharov, A. A.; Bachev, R.; Borman, G. A.; Carnerero, M. I.; Carosati, D.; Cecconi, M.; Chen, W.-P.; Damljanovic, G.; Di Paola, A.; Ehgamberdiev, Sh. A.; Frasca, A.; Giroletti, M.; González-Morales, P. A.; Griñon-Marín, A. B.; Grishina, T. S.; Huang, P.-C.; Ibryamov, S.; Klimanov, S. A.; Kopatskaya, E. N.; Kurtanidze, O. M.; Kurtanidze, S. O.; Lähteenmäki, A.; Larionova, E. G.; Larionova, L. V.; Lázaro, C.; Leto, G.; Liodakis, I.; Martínez-Lombilla, C.; Mihov, B.; Mirzaqulov, D. O.; Mokrushina, A. A.; Moody, J. W.; Morozova, D. A.; Nazarov, S. V.; Nikolashvili, M. G.; Ohlert, J. M.; Panopoulou, G. V.; Pastor Yabar, A.; Pinna, F.; Protasio, C.; Rizzi, N.; Sadun, A. C.; Savchenko, S. S.; Semkov, E.; Sigua, L. A.; Slavcheva-Mihova, L.; Strigachev, A.; Tornikoski, M.; Troitskaya, Yu. V.; Troitsky, I. S.; Vasilyev, A. A.; Vera, R. J. C.; Vince, O.; Zanmar Sanchez, R.

    2017-04-01

    In 2015 July 29-September 1, the satellite XMM-Newton pointed at the BL Lac object PG 1553+133 six times, collecting data for 218 h. During one of these epochs, simultaneous observations by the Swift satellite were requested to compare the results of the X-ray and optical-UV instruments. Optical, near-infrared and radio monitoring was carried out by the Whole Earth Blazar Telescope (WEBT) collaboration for the whole observing season. We here present the results of the analysis of all these data, together with an investigation of the source photometric and polarimetric behaviour over the last 3 yr. The 2015 EPIC spectra show slight curvature and the corresponding light curves display fast X-ray variability with a time-scale of the order of 1 h. In contrast to previous results, during the brightest X-ray states detected in 2015 the simple log-parabolic model that best fits the XMM-Newton data also reproduces reasonably well the whole synchrotron bump, suggesting a peak in the near-UV band. We found evidence of a wide rotation of the polarization angle in 2014, when the polarization degree was variable, but the flux remained almost constant. This is difficult to interpret with deterministic jet emission models, while it can be easily reproduced by assuming some turbulence of the magnetic field.

  9. Measurement method for urine puddle depth in dairy cow houses as input variable for ammonia emission modelling

    NARCIS (Netherlands)

    Snoek, J.W.; Stigter, J.D.; Ogink, Nico; Groot Koerkamp, P.W.G.

    2015-01-01

    Dairy cow houses are a major contributor to ammonia (NH3) emission in many European countries. To understand and predict NH3 emissions from cubicle dairy cow houses a mechanistic model was developed and a sensitivity analysis was performed to assess the contribution to NH3 emission of each input

  10. Variabilities in CO2 and CO over an urban site in India: Inter-correlations and emissions characteristics.

    Science.gov (United States)

    Negi, N. C.; Lal, S.; Sethuraman, V.; Patra, P. K.

    2015-12-01

    CO2, the most important greenhouse gas (GHG) in the atmosphere, plays a pivotal role in climate change. The long term increase in its atmospheric abundance after the Industrial Revolution is attributed to the emissions from anthropogenic activities, especially fossil fuel combustion. CO is a product of inefficient combustion and can be used as a surrogate tracer for identifying the anthropogenic and biospheric signal of CO2 from the atmospheric observation. India is the second largest populous country in the world and share significant contribution in the emissions of greenhouse gases mainly CO2. The budget of CO2, estimated from top-down and bottom-up approaches, shows large uncertainties over the South Asian region than other continents. One of the major sources of these large uncertainties is the lack of spatial and temporal observations. An attempt has been made using a year-long period to study the variability of the levels of CO2 and CO at an urban site Ahmedabad (23.03oN, 72.58oE, 55m AMSL), in the western India using a highly sensitive cavity ring down spectroscopy technique. The diurnal cycles of CO2 and CO show distinct features to each other due to their diverse sources and sinks. Two significant peaks during the morning and evening hours have been observed in the diurnal cycle of CO2 while in the case of CO evening peak is significantly higher than the morning peak. The afternoon levels of CO2 are observed lower during monsoon, which shows the significant uptake of CO2 from the biosphere during this season. The diurnal amplitude of CO2 is found largest around 41 ppmv in autumn and lowest around 12 ppmv in monsoon. The seasonal cycles calculated from the afternoon average monthly CO2 show the minimum levels during monsoon and maximum during spring. In case of CO minimum levels are observed in monsoon while maximum are observed in winter. The seasonal amplitude is observed around 15.02 ppmv and 0.27 ppmv for CO2 and CO respectively. Further, the co

  11. Spatial versus day-to-day within-lake variability in tropical floodplain lake CH4 emissions--developing optimized approaches to representative flux measurements.

    Directory of Open Access Journals (Sweden)

    Roberta B Peixoto

    Full Text Available Inland waters (lakes, rivers and reservoirs are now understood to contribute large amounts of methane (CH4 to the atmosphere. However, fluxes are poorly constrained and there is a need for improved knowledge on spatiotemporal variability and on ways of optimizing sampling efforts to yield representative emission estimates for different types of aquatic ecosystems. Low-latitude floodplain lakes and wetlands are among the most high-emitting environments, and here we provide a detailed investigation of spatial and day-to-day variability in a shallow floodplain lake in the Pantanal in Brazil over a five-day period. CH4 flux was dominated by frequent and ubiquitous ebullition. A strong but predictable spatial variability (decreasing flux with increasing distance to the shore or to littoral vegetation was found, and this pattern can be addressed by sampling along transects from the shore to the center. Although no distinct day-to-day variability were found, a significant increase in flux was identified from measurement day 1 to measurement day 5, which was likely attributable to a simultaneous increase in temperature. Our study demonstrates that representative emission assessments requires consideration of spatial variability, but also that spatial variability patterns are predictable for lakes of this type and may therefore be addressed through limited sampling efforts if designed properly (e.g., fewer chambers may be used if organized along transects. Such optimized assessments of spatial variability are beneficial by allowing more of the available sampling resources to focus on assessing temporal variability, thereby improving overall flux assessments.

  12. Variability in responses of bacterial communities and nitrogen oxide emission to urea fertilization among various flooded paddy soils.

    Science.gov (United States)

    Wang, Ning; Ding, Long-Jun; Xu, Hui-Juan; Li, Hong-Bo; Su, Jian-Qiang; Zhu, Yong-Guan

    2015-03-01

    Fertilization affects bacterial communities and element biogeochemical cycling in flooded paddy soils and the effect might differ among soil types. In this study, five paddy soils from Southern China were subjected to urea addition to explore impacts of fertilization on nitrogen oxide (N2O) emission and bacterial community composition under the flooding condition. 16S rRNA gene-based illumina sequencing showed no obvious shifts in bacterial community composition of five soils after urea addition. However, some genera were affected by fertilization addition and the influenced genera varied among soils. During the late period (day 8-19) of flooding incubation without urea addition, N2O emission rates were elevated for all soils. However, urea effects on N2O emission were different among flooded soils. For soils where nirS and nirK gene abundances increased with urea addition, N2O emission was significantly increased compared to control treatment. Redundancy analysis showed that dissolved organic carbon, ammonium (NH4 (+)), ferrous iron (Fe(2+)) and nitrate (NO3 (-)) in pore water explained 33.4% of the variation in soil bacterial community composition, implying that urea regimes influenced the relative abundance of some bacterial populations possibly by regulating soil characteristics and then influencing N2O emission. These results provided insights into soil type-dependent effect of fertilization on the overall bacterial communities and nitrogen oxide emission in flooded paddy soils. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Variable emissions of microbial volatile organic compounds (MVOCs) from root-associated fungi isolated from Scots pine

    Science.gov (United States)

    Bäck, Jaana; Aaltonen, Hermanni; Hellén, Heidi; Kajos, Maija K.; Patokoski, Johanna; Taipale, Risto; Pumpanen, Jukka; Heinonsalo, Jussi

    2010-09-01

    Soils emit a large variety of volatile organic compounds. In natural ecosystems, measurements of microbial volatile organic compound (MVOC) exchange rates between soil and atmosphere are difficult due to e.g. the spatial heterogeneity of the belowground organisms, and due to the many potential sources for the same compounds. We measured in laboratory conditions the MVOC emission rates and spectra of eight typical fungi occurring in boreal forest soils. The studied species are decomposers ( Gymnopilus penetrans, Ophiostoma abietinum), ectomycorrhizal ( Cenococcum geophilum, Piloderma olivaceum, Suillus variegatus, Tomentellopsis submollis) and endophytic fungi ( Meliniomyces variabilis, Phialocephala fortinii). The MVOC emissions contained altogether 21 known and 6 unidentified compounds whose emission rates were >0.1 μg g(DW) -1 h -1. The most abundant compounds were the short-chain carbonyl compounds (acetone and acetaldehyde). The greatest carbonyl emissions were measured from P. olivaceum (1.9 mg acetone g(DW) -1 h -1) and P. fortinii (0.114 mg acetaldehyde g(DW) -1 h -1). Terpenoid emissions (isoprene, mono- and sesquiterpenes) were detected from some fungal cultures, but in relatively small amounts. We conclude that soil micro-organisms can potentially be responsible for significant emissions of volatiles, especially short-chain oxygenated compounds, to the below-canopy atmosphere.

  14. Laboratory incubation experiments assessing the factor interactions affecting urine-derived nitrous oxide emissions from spatially and temporally variable upland pastures

    Science.gov (United States)

    Charteris, Alice; Loick, Nadine; Marsden, Karina; Chadwick, Dave; Whelan, Mick; Rao Ravella, Sreenivas; Mead, Andrew; Cardenas, Laura

    2017-04-01

    Urine patches deposited to soils by grazing animals represent hot-spots of nitrous oxide (N2O) emissions (Hargreaves et al., 2015), a powerful greenhouse gas (GHG) and precursor of ozone depletion in the stratosphere. Urine N2O emissions are produced via nitrification of ureolysis-derived ammonium (NH4+) and/or subsequent nitrite (NO2-) and nitrate (NO3-) denitrification (Kool et al., 2006). The dominant process and the N2O fluxes generated depend on interactions between urine characteristics (e.g. nitrogen [N] concentration and volume), soil characteristics (e.g. carbon [C] availability and pH) and preceding and prevailing environmental conditions (e.g. soil moisture and temperature; Bergstermann et al., 2011; Butterbach-Bahl et al., 2013; Dijkstra et al., 2013). The spatial and temporal variability of these interactions in grazing systems is potentially large and greatly increases the uncertainty associated with N2O emission estimates from such systems. In particular, the contribution of extensively managed upland agroecosystems, which occupy ca. 5.5 million hectares in the UK and provide the bulk of land for sheep farming (Pollott & Stone, 2004), to UK GHG emissions is poorly defined. Improving understanding of the interactions between the wide range of factors affecting urine-derived N2O production and emission from pasture soils and considering this in the context of the spatial and temporal variability of the grazing environment could therefore be extremely valuable in improving the accuracy of N2O emission estimates from such systems. The factorial laboratory incubation experiments presented have been designed to assess the interactive effects of factors such as urine N concentration, volume and soil moisture affecting soil N2O (and nitric oxide [NO], nitrogen gas [N2] and carbon dioxide [CO2]) production and emissions (García-Marco et al., 2014) using the state-of-the-art Denitrification Incubation System (DENIS). This work forms part of a wider project

  15. NATURAL GAS VARIABILITY IN CALIFORNIA: ENVIRONMENTAL IMPACTS AND DEVICE PERFORMANCE EXPERIMENTAL EVALUATION OF POLLUTANT EMISSIONS FROM RESIDENTIAL APPLIANCES

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Brett C.; Apte, Michael G.; Black, Douglas R.; Hotchi, Toshifumi; Lucas, Donald; Lunden, Melissa M.; Mirer, Anna G.; Spears, Michael; Sullivan, Douglas P.

    2009-12-01

    The effect of liquefied natural gas on pollutant emissions was evaluated experimentally with used and new appliances in the laboratory and with appliances installed in residences, targeting information gaps from previous studies. Burner selection targeted available technologies that are projected to comprise the majority of installed appliances over the next decade. Experiments were conducted on 13 cooktop sets, 12 ovens, 5 broiler burners, 5 storage water heaters, 4 forced air furnaces, 1 wall furnace, and 6 tankless water heaters. Air-free concentrations and fuel-based emission factors were determined for carbon monoxide, nitrogen oxides, nitrogen dioxide, and the number of (predominantly ultrafine) particles over complete burns?including transient effects (device warm-up and intermittent firing of burners) following ignition--and during more stable end-of-burn conditions. Formaldehyde was measured over multi-burn cycles. The baseline fuel was Northern California line gas with Wobbe number (a measure of fuel energy delivery rate) of 1320-1340; test fuels had Wobbe numbers of roughly 1390 and 1420, and in some cases 1360. No ignition or operational problems were observed during test fuel use. Baseline emissions varied widely across and within burner groups and with burner operational mode. Statistically significant emissions changes were observed for some pollutants on some burners.

  16. Characterization of dynamic thermal control schemes and heat transfer pathways for incorporating variable emissivity electrochromic materials into a space suit heat rejection system

    Science.gov (United States)

    Massina, Christopher James

    The feasibility of conducting long duration human spaceflight missions is largely dependent on the provision of consumables such as oxygen, water, and food. In addition to meeting crew metabolic needs, water sublimation has long served as the primary heat rejection mechanism in space suits during extravehicular activity (EVA). During a single eight hour EVA, approximately 3.6 kg (8 lbm) of water is lost from the current suit. Reducing the amount of expended water during EVA is a long standing goal of space suit life support systems designers; but to date, no alternate thermal control mechanism has demonstrated the ability to completely eliminate the loss. One proposed concept is to convert the majority of a space suit's surface area into a radiator such that the local environment can be used as a radiative thermal sink for rejecting heat without mass loss. Due to natural variations in both internal (metabolic) loads and external (environmental) sink temperatures, radiative transport must be actively modulated in order to maintain an acceptable thermal balance. Here, variable emissivity electrochromic devices are examined as the primary mechanism for enabling variable heat rejection. This dissertation focuses on theoretical and empirical evaluations performed to determine the feasibility of using a full suit, variable emissivity radiator architecture for space suit thermal control. Operational envelopes are described that show where a given environment and/or metabolic load combination may or may not be supported by the evaluated thermal architecture. Key integration considerations and guidelines include determining allowable thermal environments, defining skin-to-radiator heat transfer properties, and evaluating required electrochromic performance properties. Analysis also considered the impacts of dynamic environmental changes and the architecture's extensibility to EVA on the Martian surface. At the conclusion of this work, the full suit, variable emissivity

  17. Combustion and Emission Characteristics of Variable Compression Ignition Engine Fueled with Jatropha curcas Ethyl Ester Blends at Different Compression Ratio

    Directory of Open Access Journals (Sweden)

    Rajneesh Kumar

    2014-01-01

    Full Text Available Engine performance and emission characteristics of unmodified biodiesel fueled diesel engines are highly influenced by their ignition and combustion behavior. In this study, emission and combustion characteristics were studied when the engine operated using the different blends (B10, B20, B30, and B40 and normal diesel fuel (B0 as well as when varying the compression ratio from 16.5 : 1 to 17.5 : 1 to 18.5 : 1. The change of compression ratio from 16.5 : 1 to 18.5 : 1 resulted in 27.1%, 27.29%, 26.38%, 28.48%, and 34.68% increase in cylinder pressure for the blends B0, B10, B20, B30, and B40, respectively, at 75% of rated load conditions. Higher peak heat release rate increased by 23.19%, 14.03%, 26.32%, 21.87%, and 25.53% for the blends B0, B10, B20, B30, and B40, respectively, at 75% of rated load conditions, when compression ratio was increased from16.5 : 1 to 18.5 : 1. The delay period decreased by 21.26%, CO emission reduced by 14.28%, and NOx emission increased by 22.84% for B40 blends at 75% of rated load conditions, when compression ratio was increased from 16.5 : 1 to 18.5 : 1. It is concluded that Jatropha oil ester can be used as fuel in diesel engine by blending it with diesel fuel.

  18. Trends and inter-annual variability of methane emissions derived from 1979-1993 global CTM simulations

    NARCIS (Netherlands)

    Dentener, F; van Weele, M; Krol, M; Houweling, S; van Velthoven, P

    2003-01-01

    The trend and interannual variability of methane sources are derived from multi-annual simulations of tropospheric photochemistry using a 3-D global chemistry-transport model. Our semi-inverse analysis uses the fifteen years (1979-1993) re-analysis of ECMWF meteorological data and annually varying

  19. Including exposure variability in the life cycle impact assessment of indoor chemical emissions: the case of metal degreasing.

    Science.gov (United States)

    Golsteijn, Laura; Huizer, Daan; Hauck, Mara; van Zelm, Rosalie; Huijbregts, Mark A J

    2014-10-01

    The present paper describes a method that accounts for variation in indoor chemical exposure settings and accompanying human toxicity in life cycle assessment (LCA). Metal degreasing with dichloromethane was used as a case study to show method in practice. We compared the human toxicity related to the degreasing of 1m(2) of metal surface in different exposure scenarios for industrial workers, professional users outside industrial settings, and home consumers. The fraction of the chemical emission that is taken in by exposed individuals (i.e. the intake fraction) was estimated on the basis of operational conditions (e.g. exposure duration), and protective measures (e.g. local exhaust ventilation). The introduction of a time-dependency and a correction for protective measures resulted in reductions in the intake fraction of up to 1.5 orders of magnitude, compared to application of existing, less advanced models. In every exposure scenario, the life cycle impacts for human toxicity were mainly caused by indoor exposure to metal degreaser (>60%). Emissions released outdoors contributed up to 22% of the life cycle impacts for human toxicity, and the production of metal degreaser contributed up to 19%. These findings illustrate that human toxicity from indoor chemical exposure should not be disregarded in LCA case studies. Particularly when protective measures are taken or in the case of a short duration (1h or less), we recommend the use of our exposure scenario-specific approach. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Increasing synoptic scale variability in atmospheric CO2 at Hateruma Island associated with increasing East-Asian emissions

    Directory of Open Access Journals (Sweden)

    S. Hashimoto

    2010-01-01

    Full Text Available In-situ observations of atmospheric CO2 and CH4 at Hateruma Island (24.05° N, 123.80° E, 47 m a.s.l, Japan shows large synoptic scale variations during a 6-month period from November to April, when the sampled air is predominantly of continental origin due to the Asian winter monsoon. Synoptic scale variations are extracted from the daily averaged values for the years between 1996 and 2007, along with the annual standard deviations (σCO2 and σCH4 for CO2 and CH4, respectively for the relevant 6-month period. During this 6-month period the absolute mixing ratios of CO2 and CH4 at Hateruma are also elevated compared to those at two sites in the central North Pacific Ocean. The temporal change in σCO2 shows a systematic increase over the 12-year period, with elevated excursions in 1998 and 2003; there is no clear increase in σCH4. We also find that the σCO2/σCH4 ratio increases gradually from 1996 to 2002 and rapidly after 2002 without any extreme deviations that characterised σCO2. The σCO2/σCH4 ratio correlates closely with the recent rapid increase in fossil carbon emissions from China, as indicated in the Carbon Dioxide Information Analysis Center (CDIAC database. This methodology can be applied to multiple chemical tracers of sufficient lifetime, for tracking overall changes in regional emissions.

  1. Modeling regional aerosol variability over California and its sensitivity to emissions and long-range transport during the 2010 CalNex and CARES campaigns

    Science.gov (United States)

    Fast, J. D.; Allan, J.; Bahreini, R.; Craven, J.; Emmons, L.; Ferrare, R.; Hayes, P. L.; Hodzic, A.; Holloway, J.; Hostetler, C.; Jimenez, J. L.; Jonsson, H.; Liu, S.; Liu, Y.; Metcalf, A.; Middlebrook, A.; Nowak, J.; Pekour, M.; Perring, A.; Russell, L.; Sedlacek, A.; Seinfeld, J.; Setyan, A.; Shilling, J.; Shrivastava, M.; Springston, S.; Song, C.; Subramanian, R.; Taylor, J. W.; Vinoj, V.; Yang, Q.; Zaveri, R. A.; Zhang, Q.

    2014-03-01

    The performance of the Weather Research and Forecasting regional model with chemistry (WRF-Chem) in simulating the spatial and temporal variations in aerosol mass, composition, and size over California is quantified using measurements collected during the California Nexus of Air Quality and Climate Experiment (CalNex) and the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted during May and June of 2010. The extensive meteorological, trace gas, and aerosol measurements collected at surface sites and along aircraft and ship transects during CalNex and CARES were combined with operational monitoring network measurements to create a single dataset that was used to evaluate the one configuration of the model. Simulations were performed that examined the sensitivity of regional variations in aerosol concentrations to anthropogenic emissions and to long-range transport of aerosols into the domain obtained from a global model. The configuration of WRF-Chem used in this study is shown to reproduce the overall synoptic conditions, thermally-driven circulations, and boundary layer structure observed in region that controls the transport and mixing of trace gases and aerosols. However, sub-grid scale variability in the meteorology and emissions as well as uncertainties in the treatment of secondary organic aerosol chemistry likely contribute to errors at a primary surface sampling site located at the edge of the Los Angeles basin. Differences among the sensitivity simulations demonstrate that the aerosol layers over the central valley detected by lidar measurements likely resulted from lofting and recirculation of local anthropogenic emissions along the Sierra Nevada. Reducing the default emissions inventory by 50% led to an overall improvement in many simulated trace gases and black carbon aerosol at most sites and along most aircraft flight paths; however, simulated organic aerosol was closer to observed when there were no adjustments to the primary organic

  2. Quantification of Coastal Macro Algae Iodine Emissions and its Spatial Variability at the West Coast of Ireland

    Science.gov (United States)

    Pöhler, Denis; Horbanski, Martin; Schmitt, Stefan; Platt, Ulrich

    2014-05-01

    abundance in the intertidal zone, is by far the strongest source. Third, we observed also high iodine oxide levels above 30ppt at rainy, cold and windy weather. Thus former observations that these emissions arise only at sunny and warm weather could not be confirmed. Fourth, we investigated that iodine oxide increase exponentially with decreasing distance to the emitting seaweed patches reaching concentrations much above 100ppt being sufficient to start particle nucleation events. We conclude that coastal macro algae emissions are thus much more relevant for the atmosphere than so far expected from previous observations performed at Mace Head which is rather characterized by low IO levels in comparison to other locations. Reasons and explanations for these findings will be presented. A review of the coastal macro algae iodine emissions and its influence on the atmosphere is thus urgently needed.

  3. NuSTAR detection of high-energy X-ray emission and rapid variability from sagittarius A* flares

    DEFF Research Database (Denmark)

    Barrière, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.

    2014-01-01

    Sagittarius A* harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A* spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours...... at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum...... of Sagittarius A* X-ray flares extends to high energy, with no evidence for a cutoff. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra...

  4. Variable H13CO+ Emission in the IM Lup Disk: X-Ray Driven Time-dependent Chemistry?

    Science.gov (United States)

    Cleeves, L. Ilsedore; Bergin, Edwin A.; Öberg, Karin I.; Andrews, Sean; Wilner, David; Loomis, Ryan

    2017-07-01

    We report the first detection of a substantial brightening event in an isotopologue of a key molecular ion, HCO+, within a protoplanetary disk of a T Tauri star. The H13CO+ J=3-2 rotational transition was observed three times toward IM Lup between 2014 July and 2015 May with the Atacama Large Millimeter/submillimeter Array. The first two observations show similar spectrally integrated line and continuum fluxes, while the third observation shows a doubling in the disk-integrated J=3-2 line flux compared to the continuum, which does not change between the three epochs. We explore models of an X-ray active star irradiating the disk via stellar flares, and find that the optically thin H13CO+ emission variation can potentially be explained via X-ray-driven chemistry temporarily enhancing the HCO+ abundance in the upper layers of the disk atmosphere during large or prolonged flaring events. If the HCO+ enhancement is indeed caused by an X-ray flare, future observations should be able to spatially resolve these events and potentially enable us to watch the chemical aftermath of the high-energy stellar radiation propagating across the face of protoplanetary disks, providing a new pathway to explore ionization physics and chemistry, including electron density, in disks.

  5. Solar spectral irradiance variability of some chromospheric emission lines through the solar activity cycles 21-23

    Directory of Open Access Journals (Sweden)

    Göker Ü.D.

    2017-01-01

    Full Text Available A study of variations of solar spectral irradiance (SSI in the wave-length ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV spectral lines and international sunspot number (ISSN from interactive data centers such as SME (NSSDC, UARS (GDAAC, SORCE (LISIRD and SIDC, respectively. We reduced these data by using the MATLsoftware package. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm spectral lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar activity cycles (SACs 23 and 24. We also compared our results with the variations of solar activity indices obtained by the ground-based telescopes. Therefore, we found that plage regions decrease while facular areas are increasing in SAC 23. However, the decrease in plage regions is seen in small sunspot groups (SGs, contrary to this, these regions in large SGs are comparable to previous SACs or even larger as is also seen in facular areas. Nevertheless, negative correlations between ISSN and SSI data indicate that these variations are in close connection with the classes of sunspots/SGs, faculae and plage regions. Finally, we applied the time series analysis of spectral lines corresponding to the wavelengths 121.5 nm-300.5 nm and made comparisons with the ISSN data. We found an unexpected increase in the 298.5 nm line for the Fe II ion. The variability of Fe II ion 298.5 nm line is in close connection with the facular areas and plage regions, and the sizes of these solar surface indices play an important role for the SSI variability, as well. So, we compared the connection between the sizes of faculae and plage regions, sunspots/SGs, chemical elements and SSI variability. Our future work will be the theoretical study of this connection and developing of a corresponding model.

  6. Variability of SO₂, CO, and light hydrocarbons over a megacity in Eastern India: effects of emissions and transport.

    Science.gov (United States)

    Mallik, Chinmay; Ghosh, Dipanjan; Ghosh, Debreka; Sarkar, Ujjaini; Lal, Shyam; Venkataramani, S

    2014-01-01

    The Indo-Gangetic plain (IGP) has received extensive attention of the global scientific community due to higher levels of trace gases and aerosols over this region. Satellite retrievals and model simulations show that, in particular, the eastern part IGP is highly polluted. Despite this attention, in situ measurements of trace gases are very limited over this region. This paper presents measurements of SO₂, CO, CH₄, and C₂-C₅ NMHCs during March 2012-February 2013 over Kolkata, a megacity in the eastern IGP, with a focus on processes impacting their levels. The mean SO₂ and C2H6 concentrations during winter and post-monsoon periods were eight and three times higher compared to pre-monsoon and monsoon. Early morning enhancements in SO₂ and several NMHCs during winter connote boundary layer effects. Daytime elevations in SO₂ during pre-monsoon and monsoon suggest impacts of photo-oxidation. Inter-species correlations and trajectory analysis evince transport of SO₂ from regional combustion sources (e.g., coal burning in power plants, industries) along the east of the Indo-Gangetic plain impacting SO₂ levels at the site. However, C₂H₂ to CO ratio over Kolkata, which are comparable to other urban regions in India, show impacts of local biofuel combustions. Further, high levels of C₃H₈ and C₄H₁₀ evince the dominance of LPG/petrochemicals over the study location. The suite of trace gases measured during this study helps to decipher between impacts of local emissions and influence of transport on their levels.

  7. NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A{sup *} flares

    Energy Technology Data Exchange (ETDEWEB)

    Barrière, Nicolas M.; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Zoglauer, Andreas [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Baganoff, Frederick K. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139-4307 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Kgs. Lyngby (Denmark); Dexter, Jason [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States); Grefenstette, Brian; Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Hailey, Charles J.; Mori, Kaya; Zhang, Shuo [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W. [X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-05-01

    Sagittarius A{sup *} harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A{sup *} spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A{sup *} X-ray flares extends to high energy, with no evidence for a cutoff. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (∼55 times quiescence in the 2-10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse Compton models. One flare exhibits large and rapid (<100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within ∼10 Schwarzschild radii of the black hole.

  8. NuSTAR Detection of High-Energy X-Ray Emission and Rapid Variability from Sagittarius A(star) Flares

    Science.gov (United States)

    Barriere, Nicolas M.; Tomsick, John A.; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Dexter, Jason; Grefenstette, Brian; Hailey, Charles J.; Zhang, William W.

    2014-01-01

    Sagittarius A(star) harbors the supermassive black hole that lies at the dynamical center of our Galaxy. Sagittarius A(star) spends most of its time in a low luminosity emission state but flares frequently in the infrared and X-ray, increasing up to a few hundred fold in brightness for up to a few hours at a time. The physical processes giving rise to the X-ray flares are uncertain. Here we report the detection with the NuSTAR observatory in Summer and Fall 2012 of four low to medium amplitude X-ray flares to energies up to 79 keV. For the first time, we clearly see that the power-law spectrum of Sagittarius A(star) X-ray flares extends to high energy, with no evidence for a cut off. Although the photon index of the absorbed power-law fits are in agreement with past observations, we find a difference between the photon index of two of the flares (significant at the 95% confidence level). The spectra of the two brightest flares (approx. 55 times quiescence in the 2- 10 keV band) are compared to simple physical models in an attempt to identify the main X-ray emission mechanism, but the data do not allow us to significantly discriminate between them. However, we confirm the previous finding that the parameters obtained with synchrotron models are, for the X-ray emission, physically more reasonable than those obtained with inverse-Compton models. One flare exhibits large and rapid (less than 100 s) variability, which, considering the total energy radiated, constrains the location of the flaring region to be within approx. 10 Schwarzschild radii of the black hole.

  9. Analyzing the effect of seasonal water cover variability and freeze-thaw timing on methane emissions from boreal and arctic soils

    Science.gov (United States)

    Smith-Downey, N.; Fu, R.

    2009-12-01

    Here we present a new technique to detect the extent of surface water cover in boreal and arctic regions using the QuikSCAT microwave backscatter signal from 2000 to 2008, and compare these data to satellite and flask based measurements of atmospheric methane concentrations. The QuikSCAT scatterometer provides a high resolution (2.5 km, daily) long term record of fractional water cover, and is particularly sensitive to the timing of spring thaw and flooding. Interannual and seasonal variability in surface water cover drive changes in methane emissions from lakes and wetlands across the arctic and boreal region. We identify several regions where lake extent has significantly increased or decreased over the period 2000 to 2008, and evaluate changes in the seasonal cycle of water cover over this period. We combine the QuikSCAT water cover product with satellite derived estimates of soil freeze and thaw, and compare these records to atmospheric methane data from the NOAA CMDL Flask network and the satellite based TES (Aura) CH4 measurements to identify ‘pulses’ of methane emitted during periods of active freezing and thawing. We also estimate the possible effects of long-term changes in the thaw season length (from 1988 to 2009) and fractional water cover area (2000 to 2008) on methane emissions from boreal and arctic soils.

  10. Temporal variability in aerosol characteristics and its radiative properties over Patiala, northwestern part of India: Impact of agricultural biomass burning emissions.

    Science.gov (United States)

    Sharma, D; Srivastava, A K; Ram, K; Singh, A; Singh, D

    2017-12-01

    A comprehensive measurements of aerosol optical depth (AOD), particulate matter (PM) and black carbon (BC) mass concentrations have been carried out over Patiala, a semi-urban site in northwest India during October 2008 to September 2010. The measured aerosol data was incorporated in an aerosol optical model to estimate various aerosol optical parameters, which were subsequently used for radiative forcing estimation. The measured AOD at 500 nm (AOD500) shows a significant seasonal variability, with maximum value of 0.81 during post-monsoon (PoM) and minimum of 0.56 during winter season. The Ångström exponent (α) has higher values (i.e. more fine-mode fraction) during the PoM/winter periods, and lower (i.e. more coarse-mode fraction) during pre-monsoon (PrM). In contrast, turbidity coefficient (β) exhibits an opposite trend to α during the study period. BC mass concentration varies from 2.8 to 13.9 μg m(-3) (mean: 6.5 ± 3.2 μg m(-3)) during the entire study period, with higher concentrations during PoM/winter and lower during PrM/monsoon seasons. The average single scattering albedo (SSA at 500 nm) values are 0.70, 0.72, 0.82 and 0.75 during PoM, winter, PrM and monsoon seasons, respectively. However, inter-seasonal and inter-annual variability in measured aerosol parameters are statistically insignificant at Patiala. These results suggest strong changes in emission sources, aerosol composition, meteorological parameters as well as transport of aerosols over the station. Higher values of AOD, α and BC, along with lower SSA during PoM season are attributed to agriculture biomass burning emissions over and around the station. The estimated aerosol radiative forcing within the atmosphere is positive (i.e. warming) during all the seasons with higher values (∼60 Wm(-2)) during PoM-08/PoM-09 and lower (∼40 Wm(-2)) during winter-09/PrM-10. The present study highlights the role of BC aerosols from agricultural biomass burning emissions during post

  11. Long-term profile variability of double-peaked emission lines in active galactic nuclei, and, Follow-up observations of candidate tidal disruption events

    Science.gov (United States)

    Gezari, Suvi T. K.

    2005-11-01

    We present the results of over 15 years of spectroscopic monitoring of the broad, double-peaked Ha lines in a sample of seven broad-line radio galaxies with extremely broad, double-peaked line profiles that are well modeled by emission from photoionized gas in a relativistic Keplerian accretion disk around a central black hole. We use the long-term profile variability of the broad Ha lines to rule out alternative "non-accretion disk" scenarios for the source of the broad double peaked line emission, test models for dynamical processes in the accretion disk, and measure physical parameters of the accretion disk and its central black hole. Luminous UV/X-ray flares are predicted to occur in the nuclei of inactive galaxies when a star is tidally disrupted by the galaxy's central supermassive black hole, and the bound fraction of the tidal debris is accreted. The ROSAT All-Sky Survey detected several large amplitude, soft X-ray flares from galaxies with no previous evidence for AGN activity, which were best explained as tidal disruption events. We obtained follow-up optical spectroscopy of three of the flaring galaxies a decade later with the STIS and a narrow slit to search for or place stringent limits on the presence of any persistent Seyfert- like emission in their nuclei. Two of the galaxies, RX J1624.9+7554 and RX J1242.6-1119, show no evidence for emission lines or a non-stellar continuum in their HST nuclear spectra, consistent with their ground-based classification as inactive galaxies. They remain the most convincing examples of tidal disruption events to date. The GALEX Ultra-Deep Imaging Survey (UDIS) has the ideal depth, wavelength coverage, and temporal sampling for detecting flares from tidal disruption events in the nuclei of galaxies over a large range of redshifts. We describe an analysis of the capability of GALEX to detect tidal disruption events, and describe our Chandra target-of-opportunity rapid follow-up X-ray imaging program to catch the early

  12. Modeling regional aerosol and aerosol precursor variability over California and its sensitivity to emissions and long-range transport during the 2010 CalNex and CARES campaigns

    Science.gov (United States)

    Fast, J. D.; Allan, J.; Bahreini, R.; Craven, J.; Emmons, L.; Ferrare, R.; Hayes, P. L.; Hodzic, A.; Holloway, J.; Hostetler, C.; Jimenez, J. L.; Jonsson, H.; Liu, S.; Liu, Y.; Metcalf, A.; Middlebrook, A.; Nowak, J.; Pekour, M.; Perring, A.; Russell, L.; Sedlacek, A.; Seinfeld, J.; Setyan, A.; Shilling, J.; Shrivastava, M.; Springston, S.; Song, C.; Subramanian, R.; Taylor, J. W.; Vinoj, V.; Yang, Q.; Zaveri, R. A.; Zhang, Q.

    2014-09-01

    The performance of the Weather Research and Forecasting regional model with chemistry (WRF-Chem) in simulating the spatial and temporal variations in aerosol mass, composition, and size over California is quantified using the extensive meteorological, trace gas, and aerosol measurements collected during the California Nexus of Air Quality and Climate Experiment (CalNex) and the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted during May and June of 2010. The overall objective of the field campaigns was to obtain data needed to better understand processes that affect both climate and air quality, including emission assessments, transport and chemical aging of aerosols, aerosol radiative effects. Simulations were performed that examined the sensitivity of aerosol concentrations to anthropogenic emissions and to long-range transport of aerosols into the domain obtained from a global model. The configuration of WRF-Chem used in this study is shown to reproduce the overall synoptic conditions, thermally driven circulations, and boundary layer structure observed in region that controls the transport and mixing of trace gases and aerosols. Reducing the default emissions inventory by 50% led to an overall improvement in many simulated trace gases and black carbon aerosol at most sites and along most aircraft flight paths; however, simulated organic aerosol was closer to observed when there were no adjustments to the primary organic aerosol emissions. We found that sulfate was better simulated over northern California whereas nitrate was better simulated over southern California. While the overall spatial and temporal variability of aerosols and their precursors were simulated reasonably well, we show cases where the local transport of some aerosol plumes were either too slow or too fast, which adversely affects the statistics quantifying the differences between observed and simulated quantities. Comparisons with lidar and in situ measurements indicate

  13. 2FGL J0846.0+2820: A New Neutron Star Binary with a Giant Secondary and Variable γ-Ray Emission

    Science.gov (United States)

    Swihart, Samuel J.; Strader, Jay; Johnson, Tyrel J.; Cheung, C. C.; Sand, David; Chomiuk, Laura; Wasserman, Asher; Larsen, Søren; Brodie, Jean P.; Simonian, Gregory V.; Tremou, Evangelia; Shishkovsky, Laura; Reichart, Daniel E.; Haislip, Joshua

    2017-12-01

    We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated Fermi Large Area Telescope (LAT) γ-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric (e = 0.06) 8.133-day orbit with an invisible primary. Modeling the spectroscopy and photometry together led us to infer a heavy neutron star primary of ˜ 2 {M}⊙ and a partially stripped giant secondary of ˜ 0.8 {M}⊙ . Hα emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find that the γ-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then, it has not been detected by Fermi. The long period and giant secondary are reminiscent of the γ-ray bright binary 1FGL J1417.7-4407, which hosts a millisecond pulsar (MSP) apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of MSP binaries that are the likely progenitors of typical field MSPs.

  14. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China - Part 2: The roles of anthropogenic emissions and climate variability

    Science.gov (United States)

    Xu, Wanyun; Xu, Xiaobin; Lin, Meiyun; Lin, Weili; Tarasick, David; Tang, Jie; Ma, Jianzhong; Zheng, Xiangdong

    2018-01-01

    Inter-annual variability and long-term trends in tropospheric ozone are both environmental and climate concerns. Ozone measured at Mt Waliguan Observatory (WLG, 3816 m a.s.l.) on the Tibetan Plateau over the period of 1994-2013 has increased significantly by 0.2-0.3 ppbv yr-1 during spring and autumn but shows a much smaller trend in winter and no significant trend in summer. Here we explore the factors driving the observed ozone changes at WLG using backward trajectory analysis, chemistry-climate model hindcast simulations (GFDL AM3), a trajectory-mapped ozonesonde data set, and several climate indices. A stratospheric ozone tracer implemented in GFDL AM3 indicates that stratosphere-to-troposphere transport (STT) can explain ˜ 60 % of the simulated springtime ozone increase at WLG, consistent with an increase in the NW air-mass frequency inferred from the trajectory analysis. Enhanced STT associated with the strengthening of the mid-latitude jet stream contributes to the observed high ozone anomalies at WLG during the springs of 1999 and 2012. During autumn, observations at WLG are more heavily influenced by polluted air masses originating from South East Asia than in the other seasons. Rising Asian anthropogenic emissions of ozone precursors are the key driver of increasing autumnal ozone observed at WLG, as supported by the GFDL AM3 model with time-varying emissions, which captures the observed ozone increase (0.26 ± 0.11 ppbv yr-1). AM3 simulates a greater ozone increase of 0.38 ± 0.11 ppbv yr-1 at WLG in autumn under conditions with strong transport from South East Asia and shows no significant ozone trend in autumn when anthropogenic emissions are held constant in time. During summer, WLG is mostly influenced by easterly air masses, but these trajectories do not extend to the polluted regions of eastern China and have decreased significantly over the last 2 decades, which likely explains why summertime ozone measured at WLG shows no significant trend

  15. Long-Term Variability of Distortion-Product Otoacoustic Emissions in Infants and Children and Its Relation to Pediatric Ototoxicity Monitoring.

    Science.gov (United States)

    Konrad-Martin, Dawn; Knight, Kristin; McMillan, Garnett P; Dreisbach, Laura E; Nelson, Elsa; Dille, Marilyn

    2017-12-26

    Distortion-product otoacoustic emissions (DPOAEs) provide a rapid, noninvasive measure of outer hair cell damage associated with chemotherapy and are a key component of pediatric ototoxicity monitoring. Serial monitoring of DPOAE levels in reference to baseline measures is one method for detecting ototoxic damage. Interpreting DPOAE findings in this context requires that test-retest differences be considered in relation to normal variability, data which are lacking in children. This study sought to (1) characterize normal test-retest variability in DPOAE level over the long time periods reflective of pediatric chemotherapy regimens for a variety of childhood ages and f2 primary frequencies using common clinical instrumentation and stimulus parameters; (2) develop level-shift reference intervals; and (3) account for any age-related change in DPOAE level or measurement error that may occur as the auditory system undergoes maturational change early in life. Serial DPOAE measurements were obtained in 38 healthy children (25 females and 13 males) with normal hearing and ranging in age from one month to 10 years at the initial (baseline) visit. On average, children were tested 5.2 times over an observation period of 6.5 months. Data were collected in the form of DP grams, in which DPOAE level was measured for f2 ranging from 1.4 to 10 kHz, using a fixed f2/f1 ratio of 1.22 and stimulus level of 65/55 dB SPL for L1/L2. Age effects on DPOAE level and measurement error were estimated using Bayesian regression of the longitudinal data. The raw and model-based distribution of DPOAE test-retest differences were characterized using means and standard error of the measurement for several ages and f2's. DPOAE test-retest differences for the children in this study are at the high end of those previously observed in adults, as reflected in the associated shift reference intervals. Further, although we observe substantial child-specific variation in DPOAE level, the pattern of age

  16. A small-scale geostatistical analysis of the variability of soil properties driving the biogenic emission of nitric oxide from soil

    Science.gov (United States)

    Behrendt, T.; Bargsten, A.; Mamtimin, B.; Andreae, M. O.; Bruse, M.; Meixner, F. X.

    2009-04-01

    It is well known that the main steering parameters for the biogenic emission of nitrogen oxide (NO) from the soil are soil moisture, soil temperature, soil organic matter (SOM), soil nutrients, as well as soil texture and the vegetation cover. Following controlled incubation and fumigation experiments on soil samples, laboratory derived parameterization of the net NO release rate in terms of soil moisture, soil temperature and the loss in ignition (as a raw estimate of SOM) enable the calculation of net potential NO fluxes from soil. At the experimental-site „Weidenbrunnen", a mountainous spruce forest located in the Fichtelgebirge (Germany), 142 samples of organic matter and topsoil were collected. The study area (120 x 140 m) was sub-divided into three units according to differences in vegetation and insolation, as well as the position of tracks. For the sampling procedure a nested sampling design with grid intervals of 20 m, 5 m and 1.25 m was chosen. The soil properties that were analysed included the variability of the organic matter thickness, pH, C/N-ratio, loss in ignition, texture, soil temperature and top soil moisture, as well as bulk density. The relief and the understorey were included as external factors. Furthermore, the terrain elevation was measured with a TruePulse360° Laser along a geostatistical grid using supporting points in 8 different directions. Of 4 supporting points into 8 different directions, one data point was placed every 5 m. We was used this grid structure to interpolate the contour lines and identified southern exposition and a micro hilly relief (DEM). The understorey mapping was calculated by the triangulation-method while the area between the trees was divided into triangles. First of all, an experimental variogram of the appropriate grid intervals was constructed. Through the development of a model function it is possible to assign a variogram value to every distance. Across that theoretical function a spatial interpolation

  17. In vivo positron emission tomography imaging with [{sup 11}C]ABP688: binding variability and specificity for the metabotropic glutamate receptor subtype 5 in baboons

    Energy Technology Data Exchange (ETDEWEB)

    DeLorenzo, Christine; Brennan, Kathleen G. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); Milak, Matthew S.; Parsey, Ramin V. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); New York State Psychiatric Institute, New York, NY (United States); Kumar, J.S.D.; Mann, J.J. [Columbia University College of Physicians and Surgeons, Division of Molecular Imaging and Neuropathology, Department of Psychiatry, NYSPI Mail Unit 42, New York, NY (United States); New York State Psychiatric Institute, New York, NY (United States); Columbia University College of Physicians and Surgeons, Department of Radiology, New York, NY (United States)

    2011-06-15

    Metabotropic glutamate receptor subtype 5 (mGluR5) dysfunction has been implicated in several disorders. [{sup 11}C]ABP688, a positron emission tomography (PET) ligand targeting mGluR5, could be a valuable tool in the development of novel therapeutics for these disorders by establishing in vivo drug occupancy. Due to safety concerns in humans, these studies may be performed in nonhuman primates. Therefore, in vivo characterization of [{sup 11}C]ABP688 in nonhuman primates is essential. Test-retest studies were performed in baboons (Papio anubis) to compare modeling approaches and determine the optimal reference region. The mGluR5-specific antagonist 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine (MTEP) was then used in test-block studies, in which ligand binding was measured before and after MTEP administration. Test/block data were analyzed both by calculating changes in binding and using a graphical approach, which allowed estimation of both MTEP occupancy and nonspecific binding. Test-retest results, which have not been previously reported for [{sup 11}C]ABP688, indicated that [{sup 11}C]ABP688 variability is low using an unconstrained two-tissue compartment model. The most appropriate, though not ideal, reference region was found to be the gray matter of the cerebellum. Using these optimal modeling techniques on the test/block data, about 90% occupancy was estimated by the graphical approach. These studies are the first to demonstrate the specificity of [{sup 11}C]ABP688 for mGluR5 with in vivo PET in nonhuman primates. The results indicate that, in baboons, occupancy of mGluR5 is detectable by in vivo PET, a useful finding for proceeding to human studies, or performing further baboon studies, quantifying the in vivo occupancy of novel therapeutics targeting mGluR5. (orig.)

  18. Isoprene emission potentials from European oak forests derived from canopy flux measurements: an assessment of uncertainties and inter-algorithm variability

    Science.gov (United States)

    Langford, Ben; Cash, James; Acton, W. Joe F.; Valach, Amy C.; Hewitt, C. Nicholas; Fares, Silvano; Goded, Ignacio; Gruening, Carsten; House, Emily; Kalogridis, Athina-Cerise; Gros, Valérie; Schafers, Richard; Thomas, Rick; Broadmeadow, Mark; Nemitz, Eiko

    2017-12-01

    Biogenic emission algorithms predict that oak forests account for ˜ 70 % of the total European isoprene budget. Yet the isoprene emission potentials (IEPs) that underpin these model estimates are calculated from a very limited number of leaf-level observations and hence are highly uncertain. Increasingly, micrometeorological techniques such as eddy covariance are used to measure whole-canopy fluxes directly, from which isoprene emission potentials can be calculated. Here, we review five observational datasets of isoprene fluxes from a range of oak forests in the UK, Italy and France. We outline procedures to correct the measured net fluxes for losses from deposition and chemical flux divergence, which were found to be on the order of 5-8 and 4-5 %, respectively. The corrected observational data were used to derive isoprene emission potentials at each site in a two-step process. Firstly, six commonly used emission algorithms were inverted to back out time series of isoprene emission potential, and then an average isoprene emission potential was calculated for each site with an associated uncertainty. We used these data to assess how the derived emission potentials change depending upon the specific emission algorithm used and, importantly, on the particular approach adopted to derive an average site-specific emission potential. Our results show that isoprene emission potentials can vary by up to a factor of 4 depending on the specific algorithm used and whether or not it is used in a big-leaf or canopy environment (CE) model format. When using the same algorithm, the calculated average isoprene emission potential was found to vary by as much as 34 % depending on how the average was derived. Using a consistent approach with version 2.1 of the Model for Emissions of Gases and Aerosols from Nature (MEGAN), we derive new ecosystem-scale isoprene emission potentials for the five measurement sites: Alice Holt, UK (10 500 ± 2500 µg m-2 h-1); Bosco Fontana, Italy (1610

  19. Isoprene emission potentials from European oak forests derived from canopy flux measurements: an assessment of uncertainties and inter-algorithm variability

    Directory of Open Access Journals (Sweden)

    B. Langford

    2017-12-01

    Full Text Available Biogenic emission algorithms predict that oak forests account for ∼ 70 % of the total European isoprene budget. Yet the isoprene emission potentials (IEPs that underpin these model estimates are calculated from a very limited number of leaf-level observations and hence are highly uncertain. Increasingly, micrometeorological techniques such as eddy covariance are used to measure whole-canopy fluxes directly, from which isoprene emission potentials can be calculated. Here, we review five observational datasets of isoprene fluxes from a range of oak forests in the UK, Italy and France. We outline procedures to correct the measured net fluxes for losses from deposition and chemical flux divergence, which were found to be on the order of 5–8 and 4–5 %, respectively. The corrected observational data were used to derive isoprene emission potentials at each site in a two-step process. Firstly, six commonly used emission algorithms were inverted to back out time series of isoprene emission potential, and then an average isoprene emission potential was calculated for each site with an associated uncertainty. We used these data to assess how the derived emission potentials change depending upon the specific emission algorithm used and, importantly, on the particular approach adopted to derive an average site-specific emission potential. Our results show that isoprene emission potentials can vary by up to a factor of 4 depending on the specific algorithm used and whether or not it is used in a big-leaf or canopy environment (CE model format. When using the same algorithm, the calculated average isoprene emission potential was found to vary by as much as 34 % depending on how the average was derived. Using a consistent approach with version 2.1 of the Model for Emissions of Gases and Aerosols from Nature (MEGAN, we derive new ecosystem-scale isoprene emission potentials for the five measurement sites: Alice Holt, UK (10 500 ± 2500

  20. Simultaneous (68)Ga DOTATATE Positron Emission Tomography/Magnetic Resonance Imaging in Meningioma Target Contouring: Feasibility and Impact Upon Interobserver Variability Versus Positron Emission Tomography/Computed Tomography and Computed Tomography/Magnetic Resonance Imaging.

    Science.gov (United States)

    Maclean, J; Fersht, N; Sullivan, K; Kayani, I; Bomanji, J; Dickson, J; O'Meara, C; Short, S

    2017-07-01

    The increasing use of highly conformal radiation techniques to treat meningioma confers a greater need for accurate targeting. Several groups have shown that positron emission tomography/computed tomography (PET/CT) information alters meningioma targets contoured by single observers, but whether this translates into improved accuracy has not been defined. As magnetic resonance imaging (MRI) is the cornerstone of meningioma target contouring, simultaneous PET/MRI may be superior to PET/CT. We assessed whether (68)Ga DOTATATE PET imaging (from PET/CT and PET/MRI) reduced interobserver variability (IOV) in meningioma target volume contouring. Ten patients with meningioma underwent simultaneous (68)Ga DOTATATE PET/MRI followed by PET/CT. They were selected as it was anticipated that target volume definition in their cases would be particularly challenging. Three radiation oncologists contoured target volumes according to an agreed protocol: gross tumour volume (GTV) and clinical target volume (CTV) on CT/MRI alone, CT/MRI+PET(CT) and CT/MRI+PET(MRI). GTV/CTV Kouwenhoven conformity levels (KCL), regions of contour variation and qualitative differences between PET(CT) and PET(MRI) were evaluated. There was substantial IOV in contouring. GTV mean KCL: CT/MRI 0.34, CT/MRI+PET(CT) 0.38, CT/MRI+PET(MRI) 0.39 (P = 0.06). CTV mean KCL: CT/MRI 0.31, CT/MRI+PET(CT) 0.35, CT/MRI+PET(MRI) 0.35 (P = 0.04 for all groups; P > 0.05 for individual pairs). One observer consistently contoured largest and one smallest. Observers rarely decreased volumes in relation to PET. Most IOV occurred in bone followed by dural tail, postoperative bed and venous sinuses. Tumour edges were qualitatively clearer on PET(MRI) versus PET(CT), but this did not affect contouring. IOV in contouring challenging meningioma cases was large and only slightly improved with the addition of (68)Ga DOTATATE PET. Simultaneous PET/MRI for meningioma contouring is feasible, but did not improve IOV versus PET

  1. Influence of biomass burning emissions on black carbon and ozone variability in the Southern Himalayas (NCO-P, 5079 m a.s.l.)

    Science.gov (United States)

    Putero, Davide; Landi, Tony Christian; Cristofanelli, Paolo; Marinoni, Angela; Laj, Paolo; Duchi, Rocco; Adhikary, Bhupesh; Calzolari, Francescopiero; Bonafè, Ubaldo; Stocchi, Paolo; Vuillermoz, Elisa; Bonasoni, Paolo

    2013-04-01

    Black carbon (BC) and tropospheric ozone (O3) play a key role in the climate system, since they are short-lived climate forcers (SLCF) that contribute to climate change. BC and O3 precursors are emitted from several natural and anthropogenic sources; one of the most important is biomass burning, i.e. the combustion of organic matter from natural or man-made activities. Studying BC and O3 variations in connection to biomass burning is critical, mainly because of the effects that these SLCF have on the ecosystems, agriculture and human health. The issue appears urgent in several regions of the world, such as South Asia, where a vast region extending from the Indian Ocean to the Himalayas is characterized by large amounts of aerosols and pollutant gases. Here we present the variability of BC and O3 concentrations observed at the Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a.s.l.), the highest WMO-GAW global station, installed in the high Khumbu valley (Nepal, Everest region) since March 2006. Considering over 5 years of continuous measurements, the BC and O3 concentrations have shown an average value of 48.7 ± 12.6 ppbv and 208.1 ± 364.1 ng m-3, respectively. The possible contribution of open biomass burning to the average BC and O3 levels is investigated, using various satellite observations, such as MODIS fire products, the USGS Land Use Cover Characterization and TRMM rainfall measurements, linking these products to the air-mass back-trajectories reaching the sampling site (computed using LAGRANTO model). On 162 days (9% of the entire dataset), characterized by acute pollution events at NCO-P, 90 days (56%) were characterized by the transport of pollutants originated by agricultural and forest fires located in regions very close to the Himalayan sampling site. These analyses have shown that biomass burning emissions, especially at regional scale, are likely to play a key role in BC and O3 variations at NCO-P, particularly concerning the development of acute

  2. Application of Doehlert matrix and factorial designs in optimization of experimental variables associated with preconcentration and determination of molybdenum in sea-water by inductively coupled plasma optical emission spectrometry

    OpenAIRE

    Ferreira, Sergio Luis Costa; Santos,Hilda Costa dos; Carvalho, Marcelo Souza de; Fernandes, Marcelo Santiago

    2002-01-01

    p. 115–120 A simple and efficient procedure for the preconcentration and determination of molybdenum in sea-water was developed using solid-phase extraction (SPE) of molybdenum(V) ion as the thiocyanate complex by polyurethane foam and inductively coupled plasma optical emission spectrometry (ICP-OES). The optimization process was carried out using two-level full factorial and Doehlert matrix designs. Four variables (solution volume, shaking time, thiocyanate concentration and hydrochlo...

  3. Impact of public transit market share and other passenger travel variables on CO2 emissions : amassing a dataset and estimating a preliminary statistical model.

    Science.gov (United States)

    2011-12-31

    "Policies : that : encourage : the : use : of : more : efficient : transportation : modes : are : considered : beneficial : in : terms : of : reducing : carbon : dioxide : (CO2) : emissions. : In : support : of : developing : such : policies, : the :...

  4. Uncertainty in the Future Distribution of Tropospheric Ozone over West Africa due to Variability in Anthropogenic Emissions Estimates between 2025 and 2050

    Directory of Open Access Journals (Sweden)

    J. E. Williams

    2011-01-01

    Full Text Available Particle and trace gas emissions due to anthropogenic activity are expected to increase significantly in West Africa over the next few decades due to rising population and more energy intensive lifestyles. Here we perform 3D global chemistry-transport model calculations for 2025 and 2050 using both a “business-as-usual” (A1B and “clean economy” (B1 future anthropogenic emission scenario to focus on the changes in the distribution and uncertainties associated with tropospheric O3 due to the various projected emission scenarios. When compared to the present-day troposphere we find that there are significant increases in tropospheric O3 for the A1B emission scenario, with the largest increases being located in the lower troposphere near the source regions and into the Sahel around 15–20°N. In part this increase is due to more efficient NOx re-cycling related to increases in the background methane concentrations. Examining the uncertainty across different emission inventories reveals that there is an associated uncertainty of up to ~20% in the predicted increases at 2025 and 2050. For the upper troposphere, where increases in O3 have a more pronounced impact on radiative forcing, the uncertainty is influenced by transport of O3 rich air from Asia on the Tropical Easterly Jet.

  5. FLARE-LIKE VARIABILITY OF THE Mg II {lambda}2800 EMISSION LINE IN THE {gamma}-RAY BLAZAR 3C 454.3

    Energy Technology Data Exchange (ETDEWEB)

    Leon-Tavares, J. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland); Chavushyan, V.; Patino-Alvarez, V.; Carraminana, A.; Carrasco, L. [Instituto Nacional de Astrofisica Optica y Electronica (INAOE), Apartado Postal 51 y 216, 72000 Puebla (Mexico); Valtaoja, E. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-20100 Turku (Finland); Arshakian, T. G. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Popovic, L. C. [Astronomical Observatory, Volgina 7, 11160 Belgrade 74 (Serbia); Tornikoski, M.; Laehteenmaeki, A. [Aalto University Metsaehovi Radio Observatory, Metsaehovintie 114, FI-02540 Kylmaelae (Finland); Lobanov, A. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

    2013-02-01

    We report the detection of a statistically significant flare-like event in the Mg II {lambda}2800 emission line of 3C 454.3 during the outburst of autumn 2010. The highest levels of emission line flux recorded over the monitoring period (2008-2011) coincide with a superluminal jet component traversing through the radio core. This finding crucially links the broad emission line fluctuations to the non-thermal continuum emission produced by relativistically moving material in the jet and hence to the presence of broad-line region clouds surrounding the radio core. If the radio core were located at several parsecs from the central black hole, then our results would suggest the presence of broad-line region material outside the inner parsec where the canonical broad-line region is envisaged to be located. We briefly discuss the implications of broad emission line material ionized by non-thermal continuum in the context of virial black hole mass estimates and gamma-ray production mechanisms.

  6. Interannual variability of nitrogen oxides emissions from boreal fires in Siberia and Alaska during 1996–2011 as observed from space

    NARCIS (Netherlands)

    Tanimoto, H.; Ikeda, K.; Boersma, K.F.; A, van der R.J.; Garivait, S.

    2015-01-01

    Past studies suggest that forest fires contribute significantly to the formation of ozone in the troposphere. However, the emissions of ozone precursors from wildfires, and the mechanisms involved in ozone production from boreal fires, are very complicated. Moreover, an evaluation of the role of

  7. State density formalism of the Iwamoto-Harada model: A suitable tool to treat cluster emission from heavy-ion collisions with account for spin variables

    Directory of Open Access Journals (Sweden)

    Běták Emil

    2017-01-01

    Full Text Available We study the possibility to include the cluster emission into the statistical pre-equilibrium (exciton model suitable also for heavy ion collisions. The direct motivation of this paper is a possibility of producing superdeformed nuclei, which are easier to be detected in heavy-ion reactions than in those induced by light projectiles (nucleons, deuterons, α-particles.

  8. Temporal variability of CO2 and N2O emissions in an agricultural long-term field trial regarding effects of different management practices and extreme weather effects

    Science.gov (United States)

    Koal, Philipp; Schilling, Rolf; Gerl, Georg; Pritsch, Karin; Munch, Jean Charles

    2016-04-01

    In order to achieve a reduction of greenhouse gas emissions, modern agronomic management practices need to be established. Therefore, to assess the effect of different farming practices on greenhouse gas emissions, reliable data are required. The experiment covers and compares main aspects of agricultural management for a better implementation of sustainable land use. The focus lies on the determination and interpretation of greenhouse gas emissions, where the effects of diverse tillage systems and fertilisation practices of an integrated farming system as well as the impacts of extreme weather conditions are observed. In addition, with analysis of the alterable biological, physical and chemical soil properties a link between the impact of different management systems on greenhouse gas emissions and the observed cycle of matter in the soil, especially the nitrogen and carbon cycle, is enabled. Measurements have been carried out on long-term field trials at the Research Farm Scheyern located in a Tertiary hilly landscape approximately 40 km north of Munich (South Germany). The long-term integrated farming system trial was started in 1992. Since then parcels of land (each around 0.2-0.4 ha) with a particular interior plot set-up have been conducted with the same crop rotation, tillage and fertilisation practice referring to integrated farming management. Thus, the management impacts on the soil of more than 20 years have been examined. Fluxes of CH4, N2O and CO2 have been monitored since 2007 for the integrated farming system trial using an automated system which consists of chambers (0.4 m2 area) with a motor-driven lid, an automated gas sampling unit, an on-line gas chromatographic analysis system, and a control and data logging unit. Precipitation and temperature data have been observed for the experimental field to include weather effects. The main outcomes are the analysis of temporal and spatial dynamics of greenhouse gas emissions influenced by management

  9. Nitrogen loss from high N-input vegetable fields - a) direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    Science.gov (United States)

    Pfab, H.; Ruser, R.; Palmer, I.; Fiedler, S.

    2009-04-01

    Nitrous oxide is a climate relevant trace gas. It contributes 7.9 % to the total anthropogenic greenhouse gas emission and it is also involved in stratospheric ozone depletion. Approximately 85 % of the anthropogenic N2O emissions result from agricultural activities, more than 50 % are produced during microbial N-turnover processes in soils. Especially soils with high N-input (N-fertilizer and high amount of N in plant residues) like vegetable cropped soils are assumed to cause high N2O losses. The aims of the study presented were (i) to quantify the N2O loss from a vegetable field (lettuce-cauliflower crop rotation), (ii) to calculate an emission factor for the study site in Southwest Germany and to compare this factor with the default value provided by the IPCC (2006) and (iii) to test the emission reduction potential (Ammonium Sulfate Nitrate fertilizer, ASN either by reduced N-fertilization) in comparison with common N doses used for good agricultural practice or by the use of a nitrification inhibitor (DMPP), a banded N-application (lettuce) or a depot fertilization measure (pseudo-CULTAN in order to suppress nitrification). N2O fluxes determined with the closed chamber method were highly variable in time with strongly increased flux rates after N-fertilization in combination with rainfall or irrigation measures and after the incorporation of cauliflower crop residues. Using the mean soil nitrate contents of the top soil of our investigated treatments (0-25 cm depth), we could explain approximately 60 % of the variability of the cumulative N2O losses during the vegetation period of lettuce and cauliflower. The cumulative N2O emissions ranged between 0,99 kg N2O-N ha-1 from the unfertilized control plots (vegetation period) and 6,81 kg N2O-N ha-1 from the plots with the highest N-dose. Based on the guidelines of the IPCC (2006), we calculated an emission factor around 0,9 % for the cropping season. This value is in good agreement with the default value of the

  10. Variabilidade espacial da emissão de CO2 em Latossolos sob cultivo de cana-de-açúcar em diferentes sistemas de manejo Spatial variability of CO2 emission on Oxisol soils cultivated with sugar cane under different management practices

    Directory of Open Access Journals (Sweden)

    Alan R. Panosso

    2008-06-01

    Full Text Available Neste trabalho, foi determinada a estrutura da variabilidade espacial da emissão de CO2, temperatura e umidade de solos desprovidos de vegetação em duas localidades sob cultivo da cana-de-açúcar, em sistemas de manejos de cana crua e de cana queimada, no nordeste do Estado de São Paulo. A emissão de CO2 e a temperatura do solo foram registradas utilizando-se de câmara de fluxo portátil e sensor de temperatura do sistema LI-6400. A umidade foi avaliada utilizando sistema portátil TDR. A maior emissão foi observada no local sob manejo de cana queimada, com valor médio de 2,05 μmol m-2 s-1, porém a dependência espacial na emissão de CO2 foi encontrada somente na área sob manejo de cana crua. Os mapas de krigagem da emissão de CO2, temperatura e umidade do solo sob manejo de cana queimada mostraram correspondência à declividade do terreno, com as maiores emissões e temperaturas localizadas na parte mais alta, sendo as maiores umidades do solo encontradas na parte mais baixa do local estudado. Os resultados indicam correlação linear positiva da emissão de CO2 com a temperatura, e negativa com a umidade do solo somente no local com manejo de cana queimada, e não no sistema de cana crua, onde a presença de palhada certamente impede a ação direta da radiação solar e o escoamento de chuvas.In this work, it was determined the spatial variability structure of soil CO2 emission, the temperature and the soil moisture in two locations currently cultivated with sugar cane and submitted to different management systems: slash/burn and no-till, in the northeast of São Paulo State. The soil CO2 emission and the soil temperature were registered by using a portable chamber and a temperature sensor of LI-6400 system. Soil moisture was measured by a portable TDR system. The highest emission was observed in the slash and burn plot, with an average value of 2.05 μmol m-2 s-1, but spatial variability structure was observed just for the CO2

  11. The detection of variable radio emission from the fast rotating magnetic hot B-star HR\\xA07355 and evidence for its X-ray aurorae

    Science.gov (United States)

    Leto, P.; Trigilio, C.; Oskinova, L.; Ignace, R.; Buemi, C. S.; Umana, G.; Ingallinera, A.; Todt, H.; Leone, F.

    2017-05-01

    In this paper, we investigate the multiwavelength properties of the magnetic early B-type star HR 7355. We present its radio light curves at several frequencies, taken with the Jansky Very Large Array, and X-ray spectra, taken with the XMM-Newton X-ray telescope. Modelling of the radio light curves for the Stokes I and V provides a quantitative analysis of the HR 7355 magnetosphere. A comparison between HR 7355 and a similar analysis for the Ap star CU Vir allows us to study how the different physical parameters of the two stars affect the structure of the respective magnetospheres where the non-thermal electrons originate. Our model includes a cold thermal plasma component that accumulates at high magnetic latitudes that influences the radio regime, but does not give rise to X-ray emission. Instead, the thermal X-ray emission arises from shocks generated by wind stream collisions close to the magnetic equatorial plane. The analysis of the X-ray spectrum of HR 7355 also suggests the presence of a non-thermal radiation. Comparison between the spectral index of the power-law X-ray energy distribution with the non-thermal electron energy distribution indicates that the non-thermal X-ray component could be the auroral signature of the non-thermal electrons that impact the stellar surface, the same non-thermal electrons that are responsible for the observed radio emission. On the basis of our analysis, we suggest a novel model that simultaneously explains the X-ray and the radio features of HR 7355 and is likely relevant for magnetospheres of other magnetic early-type stars.

  12. Eddy covariance flux measurements confirm extreme CH4 emissions from a Swiss hydropower reservoir and resolve their short-term variability

    Directory of Open Access Journals (Sweden)

    S. Sobek

    2011-09-01

    Full Text Available Greenhouse gas budgets quantified via land-surface eddy covariance (EC flux sites differ significantly from those obtained via inverse modeling. A possible reason for the discrepancy between methods may be our gap in quantitative knowledge of methane (CH4 fluxes. In this study we carried out EC flux measurements during two intensive campaigns in summer 2008 to quantify methane flux from a hydropower reservoir and link its temporal variability to environmental driving forces: water temperature and pressure changes (atmospheric and due to changes in lake level. Methane fluxes were extremely high and highly variable, but consistently showed gas efflux from the lake when the wind was approaching the EC sensors across the open water, as confirmed by floating chamber flux measurements. The average flux was 3.8 ± 0.4 μg C m−2 s−1 (mean ± SE with a median of 1.4 μg C m−2 s−1, which is quite high even compared to tropical reservoirs. Floating chamber fluxes from four selected days confirmed such high fluxes with 7.4 ± 1.3 μg C m−2 s−1. Fluxes increased exponentially with increasing temperatures, but were decreasing exponentially with increasing atmospheric and/or lake level pressure. A multiple regression using lake surface temperatures (0.1 m depth, temperature at depth (10 m deep in front of the dam, atmospheric pressure, and lake level was able to explain 35.4% of the overall variance. This best fit included each variable averaged over a 9-h moving window, plus the respective short-term residuals thereof. We estimate that an annual average of 3% of the particulate organic matter (POM input via the river is sufficient to sustain these large CH4 fluxes. To compensate the global warming potential associated with the CH4 effluxes from this hydropower reservoir a 1.3 to 3.7 times larger terrestrial area with net carbon dioxide uptake is needed if a European-scale compilation of grasslands, croplands and forests is taken as reference. This

  13. The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron Kα line

    DEFF Research Database (Denmark)

    Marinucci, A.; Matt, G.; Bianchi, S.

    2015-01-01

    We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suz......We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM...... is found and, by using temporal information collected over more than a decade, we investigate variations of the iron Kα line on time-scales of years. The Fe K alpha line is likely the sum of two components: one constant (originating from distant Compton-thick material) and the other one variable...

  14. Effect of climate, intra and inter-annual variability, on nutrients emission (C,N, P) in stream water: lessons from an agricultural long term observatory of the temperate zone

    Science.gov (United States)

    Gascuel-Odoux, Chantal; Remi, Dupas; Patrick, Durand; Ophélie, Fovet; Gerard, Gruau; Anne, Jaffrezic; Guillaume, Humbert; Philippe, Merot; Gu, Sen

    2016-04-01

    Agriculture greatly contributes to modify C, N and P cycles, particularly in animal breeding regions due to high inputs. Climatic conditions, intra and inter-annual variabilities, modify nutrient stream water emissions, acting in time on transfer and transformation, accumulation and mobilization processes, connecting and disconnecting in time different compartments (soil, riparian areas, groundwater). In agricultural catchments, nutrient perturbations are dominated by agricultural land use, and decoupling human activities and climate effects is far from easy. Climate change generally appears as a secondary driver compared to land use. If studied, generally only one nutrient is considered. Only long term, high frequency and multiple element data series can decouple these two drivers. The Kervidy-Naizin watershed belongs to the AgrHyS environmental research observatory (http://www6.inra.fr/ore_agrhys_eng), itself included in RBV (French catchment network of the CZO). On this catchment, 6 years of daily data on DOC, NO3, SRP, TP concentrations allow us to analyze the effect of seasonal and inter-annual climatic variabilities on water quality (C, N, P). Different papers have been published on the effect of climate on nitrate (Molenat et al, 2008), SRP and TP (Dupas et al, 2015) and DOC (Humbert et al, 2015). We will present first results comparing the effect of climate on these three major solute forms of C, N and P. While C and P dynamics are very close and controlled by fluctuation of water table downslope, i.e. in riparian areas, mobilizing C and P in time, nitrate dynamics is controlled by GW dynamics upslope acting as the major N reservoir. As example, the dryness conditions in summer appears a key factor of the C and P emissions in autumn. All the three solute forms interact when anoxic conditions are observed in riparian zones. These basic processes explain how climatic variability can influence and explain interactions between C, N and P emissions in stream

  15. Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES)

    Science.gov (United States)

    Calvin, W. M.; Titus, T. N.

    2008-02-01

    Previous observations have noted the change in albedo in a number of North Pole bright outliers and in the distribution of bright ice deposits between Mariner 9, Viking, and Mars Global Surveyor (MGS) data sets. Changes over the summer season as well as between regions at the same season ( Ls) in different years have been observed. We used the bolometric albedo and brightness temperature channels of the Thermal Emission Spectrometer (TES) on the MGS spacecraft to monitor north polar residual ice cap variations between Mars years and within the summer season for three northern Martian summers between July 1999 and April 2003. Large-scale brightness variations are observed in four general areas: (1) the patchy outlying frost deposits from 90 to 270°E, 75 to 80°N; (2) the large "tail" below the Chasma Boreale and its associated plateau from 315 to 45°E, 80 to 85°N, that we call the "Boreale Tongue" and in Hyperboreae Undae; (3) the troughed terrain in the region from 0 to 120°E longitude (the lower right on a polar stereographic projection) we have called "Shackleton's Grooves" and (4) the unit mapped as residual ice in Olympia Planitia. We also note two areas which seem to persist as cool and bright throughout the summer and between Mars years. One is at the "source" of Chasma Boreale (˜15°E, 85°N) dubbed "McMurdo", and the "Cool and Bright Anomaly (CABA)" noted by Kieffer and Titus 2001. TES Mapping of Mars' north seasonal cap. Icarus 154, 162-180] at ˜330°E, 87°N called here "Vostok". Overall defrosting occurs early in the summer as the temperatures rise and then after the peak temperatures are reached ( Ls˜110) higher elevations and outlier bright deposits cold trap and re-accumulate new frost. Persistent bright areas are associated with either higher elevations or higher background albedos suggesting complex feedback mechanisms including cold-trapping of frost due to albedo and elevation effects, as well as influence of mesoscale atmospheric dynamics.

  16. Inhalation of diluted diesel engine emission impacts heart rate variability and arrhythmia occurrence in a rat model of chronic ischemic heart failure

    Energy Technology Data Exchange (ETDEWEB)

    Anselme, Frederic [Rouen University Hospital, Service de Cardiologie, Rouen (France); Loriot, Stephane; Henry, Jean-Paul; Thuillez, Christian; Morin, Jean-Paul [University of Rouen France, INSERM U644, School of Medicine-Pharmacy, Rouen, Cedex (France); Dionnet, Frederic [Centre d' Etudes et de Recherches Technologiques en Aerothermique et Moteurs, Saint Etienne du Rouvray (France); Napoleoni, Jean-Gerard [EMKA Technologies, Paris (France)

    2007-04-15

    Both increase in cardiac arrhythmia incidence and decrease in heart rate variability (HRV) have been described following human and experimental animal exposures to air pollutants. However, the potential causal relationship between these two factors remains unclear. Incidence of ventricular arrhythmia and HRV were evaluated during and after a 3 h period of Diesel engine exhaust exposure in ten healthy and ten chronic ischemic heart failure (CHF, 3 months after coronary ligation) Wistar rats using implantable ECG telemetry. Air pollutants were delivered to specifically designed whole body individual exposure chambers at particulate matter concentrations similar to those measured inside cabins of cars inserted in congested urban traffic. Recordings were obtained from unrestraint and unsedated vigil rats. Immediate decrease in RMSSD was observed in both healthy (6.64 {+-} 2.62 vs. 4.89 {+-} 1.67 ms, P < 0.05) and CHF rats (8.01 {+-} 0.89 vs. 6.6 {+-} 1.37 ms, P < 0.05) following exposure. An immediate 200-500% increase in ventricular premature beats was observed in CHF rats only. Whereas HRV progressively returned to baseline values within 2.5 h after exposure start, the proarrhythmic effect persisted as late as 5 h after exposure termination in CHF rats. Persistence of ventricular proarrhythmic effects after HRV normalization suggests that HRV reduction is not the mechanism of cardiac arrhythmias in this model. Our methodological approach, closely reflecting the real clinical situations, appeared to be a unique tool to provide further insight into the pathophysiological mechanisms of traffic related airborne pollution health impact. (orig.)

  17. Global Seabird Ammonia Emissions

    Science.gov (United States)

    Riddick, S. N.; Blackall, T. D.; Dragosits, U.; Daunt, F. H.; Braban, C. F.; Tang, Y. S.; Trathan, P.; Wanless, S.; Sutton, M. A.

    2010-12-01

    Seabird colonies represent a major source of atmospheric ammonia (NH3) in remote coastal and marine systems in temperate, tropical and polar regions. Previous studies have shown that NH3 emissions from Scottish seabird colonies were substantial - of similar magnitude to the most intensive agricultural point source emissions. The UK data were used to model global seabird NH3 emissions and suggested that penguins are a major source of emissions on and around the Antarctic continent. The largest seabird colonies are in the order of millions of seabirds. Due to the isolation of these colonies from anthropogenic nitrogen sources, they may play a major role in the nitrogen cycle within these ecosystems. A global seabird database was constructed and used in conjunction with a species-specific seabird bioenergetics model to map the locations of NH3 emissions from seabird colonies. The accuracy of the modelled emissions was validated with field data of NH3 emissions measured at key seabird colonies in different climatic regions of the world: temperate (Isle of May, Scotland), tropical (Ascension Island) and polar (Signy Island, South Georgia). The field data indicated good agreement between modelled and measured NH3 emissions. The measured NH3 emissions also showed the variability of emission with climate. Climate dependence of seabird NH3 emissions may have further implications under a changing global climate. Seabird colonies represent NH3 emission ‘hotspots’, often far from anthropogenic sources, and are likely to be the major source of nitrogen input to these remote coastal ecosystems. The direct manuring by seabirds at colony locations may strongly influence species richness and biodiversity. The subsequent volatilisation and deposition of NH3 increases the spatial extent of seabird influence on nitrogen cycling in their local ecosystem. As many seabird populations are fluctuating due to changing food supply, climate change or anthropogenic pressures, these factors

  18. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this

  19. Rapidly variable relatvistic absorption

    Science.gov (United States)

    Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

    2017-10-01

    I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

  20. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC Education | GIS Inventory — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  1. Emission inventory; Inventaire des emissions

    Energy Technology Data Exchange (ETDEWEB)

    Fontelle, J.P. [CITEPA, Centre Interprofessionnel Technique d`Etudes de la Pollution Atmospherique, 75 - Paris (France)

    1997-12-31

    Statistics on air pollutant (sulfur dioxide, nitrogen oxides and ammonium) emissions, acid equivalent emissions and their evolution since 1990 in the various countries of Europe and the USA, are presented. Emission data from the industrial, agricultural, transportation and power sectors are given, and comparisons are carried out between countries based on Gnp and population, pollution import/export fluxes and compliance to the previous emission reduction objectives

  2. Application of factorial designs and Doehlert matrix in optimization of experimental variables associated with the preconcentration and determination of vanadium and copper in seawater by inductively coupled plasma optical emission spectrometry

    Science.gov (United States)

    Ferreira, Sérgio L. C.; Queiroz, Adriana S.; Fernandes, Marcelo S.; dos Santos, Hilda C.

    2002-12-01

    In the present paper a procedure for preconcentration and determination of vanadium and copper in seawater using inductively coupled plasma optical emission spectrometry (ICP OES) is proposed, which is based on solid-phase extraction of vanadium (IV), vanadium (V) and copper (II) ions as 1-(2-pyridylazo)-2-naphthol (PAN) complexes by active carbon. The optimization process was carried out using two-level full factorials and Doehlert matrix designs. Four variables (PAN mass, pH, active carbon mass and shaking time) were regarded as factors in the optimization. Results of the two-level full factorial design 2 4 with 16 runs for vanadium extraction, based on the variance analysis (ANOVA), demonstrated that the factors pH and active carbon mass, besides the interaction (pH×active carbon mass), are statistically significant. For copper, the ANOVA revealed that the factors PAN mass, pH and active carbon mass and the interactions (PAN mass×pH) and (pH×active carbon mass) are statistically significant. Doehlert designs were applied in order to determine the optimum conditions for extraction. The procedure proposed allowed the determination of vanadium and copper with detection limits (3σ/ S) of 73 and 94 ng l -1, respectively. The precision, calculated as relative standard deviation (R.S.D.), was 1.22 and 1.37% for 12.50 μg l -1 of vanadium and copper, respectively. The preconcentration factor was 80. The recovery achieved for determination of vanadium and copper in the presence of several cations demonstrated that this procedure improved the selectivity required for seawater analysis. The procedure was applied to the determination of vanadium and copper in seawater samples collected in Salvador City, Brazil. Results showed good agreement with other data reported in the literature.

  3. Microscopic Fuel Consumption and Emission Modeling

    OpenAIRE

    Ahn, Kyoungho

    1998-01-01

    Mathematical models to predict vehicle fuel consumption and emission metrics are presented in this thesis. Vehicle fuel consumption and emissions are complex functions to be approximated in practice due to numerous variables affecting their outcome. Vehicle energy and emissions are particularly sensitive to changes in vehicle state variables such as speed and acceleration, ambient conditions such as temperature, and driver control inputs such as acceleration pedal position and gear shift spee...

  4. The Astrophysics of Emission-Line Stars

    CERN Document Server

    Kogure, Tomokazu

    2007-01-01

    Many types of stars show conspicuous emission lines in their optical spectra. These stars are broadly referred to as emission line stars. Emission line stars are attractive to many people because of their spectacular phenomena and their variability. The Astrophysics of Emission Line Stars offers general information on emission line stars, starting from a brief introduction to stellar astrophysics, and then moving toward a broad overview of emission line stars including early and late type stars as well as pre-main sequence stars. Detailed references have been prepared along with an index for further reading.

  5. Nitrogen loss from high N-input vegetable fields: a) Direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    Science.gov (United States)

    Palmer, I.; Pfab, H.; Ruser, R.; Fiedler, S.

    2009-04-01

    Nitrous oxide (N2O) is a greenhouse gas contributing to stratospheric ozone depletion. Soils are considered to be the major (70%) source for atmospheric N2O. Agriculture in general accounts for about 85% of the anthropogenic N2O emissions. Whereas 80% of these, are emitted from ag-riculturally used soils. Such estimations of N2O fluxes are associated with a high degree of uncertainties. Uncertainty of source strength estimates mainly results from local scale variability of known and unknown sources. It is not known how much uncertainty is due to unmeasured sources. For example, considerations of N2O fluxes from soils used for intensive vegetable production within inventories are still missing. We speculate that these types of arable soils act as ‚hot spots' for N2O. Given conditions (1) high N-input due to fertilization in concert with (2) easily mineralizable harvest residues should pro-mote disproportional high reaction rates in N-cycling and enhance N2O production as a by-product of nitrification and denitrification. Our investigation focused on the influence of: (1) N-input level (Ammonium Sulfate Nitrate (ASN)) below and above common N doses used for "good agricultural practice". (2) Application of modified fertilizers including nitrification inhibitor DMPP (Dimethylpyrazolphosphate, ENTEC®) and depot fertilization (pseudo-CULTAN) in comparison to non-fertilized control and common ASN application. (3) Effects of plant residues on N-cycling and (4) the deduction of mitigation strategies to reduce the potential N-loss from theses sites. The study was carried out during summer and autumn 2008 on a field cropped with cauliflower, located at the "Heidfeldhof" (South-West Germany; MAT 10.5°C, MAP 660 mm). Three different N-species (N2O; within gaseous soil phase, ammonium (NH4+) and nitrate (NO3-) extracted from bulk soil) were measured weekly in three different soil depths (0-25 cm; 25-50 cm and 50-75 cm) in a fully randomized field design. At same depths water

  6. Emission detectors

    CERN Document Server

    Bolozdynya, Alexander I

    2010-01-01

    After decades of research and development, emission detectors have recently become the most successful instrumentation used in modern fundamental experiments searching for cold dark matter, and are also considered for neutrino coherent scattering and magnetic momentum neutrino measurement. This book is the first monograph exclusively dedicated to emission detectors. Properties of two-phase working media based on noble gases, saturated hydrocarbon, ion crystals and semiconductors are reviewed.

  7. Ashtekar variables

    Science.gov (United States)

    Ashtekar, Abhay

    2015-05-01

    In the spirit of Scholarpedia, this invited article is addressed to students and younger researchers. It provides the motivation and background material, a summary of the main physical ideas, mathematical structures and results, and an outline of applications of the connection variables for general relativity. These variables underlie both the canonical/Hamiltonian and the spinfoam/path integral approaches in loop quantum gravity.

  8. Variability Bugs:

    DEFF Research Database (Denmark)

    Melo, Jean

    2017-01-01

    be exploited. Variability bugs are not confined to any particular type of bug, error-prone feature, or location. In addition to introducing an exponential number of program variants, variability increases the complexity of bugs due to unintended feature interactions, hidden features, combinations of layers...... and bug finding, but not terribly so. This is positive and consistent with the existence of highly-configurable software systems with hundreds, even thousands, of features, testifying that developers in the trenches are able to deal with variability.......Many modern software systems are highly configurable. They embrace variability to increase adaptability and to lower cost. To implement configurable software, developers often use the C preprocessor (CPP), which is a well-known technique, mainly in industry, to deal with variability in code...

  9. Complex variables

    CERN Document Server

    Fisher, Stephen D

    1999-01-01

    The most important topics in the theory and application of complex variables receive a thorough, coherent treatment in this introductory text. Intended for undergraduates or graduate students in science, mathematics, and engineering, this volume features hundreds of solved examples, exercises, and applications designed to foster a complete understanding of complex variables as well as an appreciation of their mathematical beauty and elegance. Prerequisites are minimal; a three-semester course in calculus will suffice to prepare students for discussions of these topics: the complex plane, basic

  10. Emissivity modulating electrochromic device

    Science.gov (United States)

    Demiryont, Hulya; Shannon, Kenneth C., III; Sheets, Judd

    2009-05-01

    The IR-ECDTM (Infra-Red ElectroChromic Device) variable emitance device (VED) is an all-solid-state monolithic vacuum deposited thin film system with a unique metamaterial IR transparent-electrode system which functions as an electrically controlled dimmable mirror in the IR region. The maximum reflectance corresponding to the bleached condition of the system is around 90% (low-e condition, e=0.1). The minimum reflectance reaches nearly zero in the colored condition of the system (high emittance, e=1). The average emissivity modulation of the IRECDTM is 0.7 in the 8-12 micron region, and at 9.7 micron (room temperature) it reaches a value of 0.9. Half and full emissivity modulations occur within 2 and10 minutes respectively. Because of its light weight (5g/m2), low voltage requirement (+/- 1 Volts), extremely good emissivity control properties (from 0 to 0.9 at 300K) and highly repeatable deposition process, the IR-ECDTM technology is very attractive for satellite thermal control applications. The IR-ECDTM has been under evaluation in a real space environment since March 8, 2007. This paper presents recent achievements of the IR-ECDTM including space test results.

  11. Variability of Disk Emission in Pre-main Sequence and Related Stars. IV. Occultation Events from the Innermost Disk Region of the Herbig AE Star HD 163296 = MWC 275

    Science.gov (United States)

    Pikhartova, Monika; Long, Zachary; Fernandes, Rachel; Sitko, Michael; Grady, Carol; Rich, Evan; Wisniewski, John

    2018-01-01

    We studied the structure and the dynamics of the innermost region of the circumstellar disk around the star HD 163296, MWC 275. We extracted the emission line strengths of Pa beta and Br gamma and calculated the line fluxes, from which we then computed the mass accretion rates onto the star. We investigated the brightness drop at visible wavelengths in 2001 using the Monte Carlo Radiative Transfer Code, hochunk3d. Since the star has bipolar outflows, we looked at whether changes in the outflow, with dust entrained with the gas, could produce such a drop in brightness. We fitted data from 2001 and 2005 onto SED and temperaturedensity models of the disk and generated JHK disk images, then noted the changes in image brightness and in SED plots. Our models succesfully produce the drop in brightness.

  12. Complex variables

    CERN Document Server

    Flanigan, Francis J

    2010-01-01

    A caution to mathematics professors: Complex Variables does not follow conventional outlines of course material. One reviewer noting its originality wrote: ""A standard text is often preferred [to a superior text like this] because the professor knows the order of topics and the problems, and doesn't really have to pay attention to the text. He can go to class without preparation."" Not so here-Dr. Flanigan treats this most important field of contemporary mathematics in a most unusual way. While all the material for an advanced undergraduate or first-year graduate course is covered, discussion

  13. Complex variables

    CERN Document Server

    Taylor, Joseph L

    2011-01-01

    The text covers a broad spectrum between basic and advanced complex variables on the one hand and between theoretical and applied or computational material on the other hand. With careful selection of the emphasis put on the various sections, examples, and exercises, the book can be used in a one- or two-semester course for undergraduate mathematics majors, a one-semester course for engineering or physics majors, or a one-semester course for first-year mathematics graduate students. It has been tested in all three settings at the University of Utah. The exposition is clear, concise, and lively

  14. Low emission internal combustion engine

    Science.gov (United States)

    Karaba, Albert M.

    1979-01-01

    A low emission, internal combustion compression ignition engine having a cylinder, a piston movable in the cylinder and a pre-combustion chamber communicating with the cylinder near the top thereof and in which low emissions of NO.sub.x are achieved by constructing the pre-combustion chamber to have a volume of between 70% and 85% of the combined pre-chamber and main combustion chamber volume when the piston is at top dead center and by variably controlling the initiation of fuel injection into the pre-combustion chamber.

  15. Modelling of ammonia emissions from dairy cow houses

    NARCIS (Netherlands)

    Monteny, G.J.

    2000-01-01

    Dairy cow husbandry contributes to environmental acidification through the emission of ammonia. In-depth knowledge on the processes and variable factors that play a role in the emission of ammonia from dairy cow houses benefits the production of emission data, the development of low

  16. Emissions trading under market imperfections

    Energy Technology Data Exchange (ETDEWEB)

    Lappi, P.

    2013-08-15

    In this thesis we consider emissions trading under various market imperfections such as uncertainty over permit price, imperfect competition and noncompliance. First, we study the effects of uncertain permit price on the firms choice of emission intensive and clean inputs in an multi-input production process. We also assess the risk aversion factors of some Finnish heat and power producers. Second, we study imperfect competition in output and permit markets with a two-stage model, where output decision is made before permit trades. The emphasis is on the strategic interaction between firms and on the efficiency increasing regulation. Third, we turn back to uncertainty and analyse the welfare difference between emissions trading and emission tax, when some of the firms may be noncompliant. The main finding is that welfare is greater with emission tax than with emissions trading, when at least one firm is noncompliant. Finally, we extend some existing models of permit banking and borrowing to encompass also noncompliant behavior of firms. Here, we analyse the incentives of compliant firms to become noncompliant at some point in time and also the time paths of the choice variables. (orig.)

  17. Emission Inventory for Fugitive Emissions in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2007. The inventory of fugitive emissions includes CO2, CH4, N2O, NOx, CO, NMVOC, SO2, dioxin, PAH and particulate matter. In 2007 the total Danish emission of greenhouse...

  18. Airborne observations reveal elevational gradient in tropical forest isoprene emissions

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Dasa; Guenther, Alex B.; Shilling, John E.; Yu, Haofei; Huang, Maoyi; Zhao, Chun; Yang, Qing; Martin, Scot T.; Artaxo, Paulo; Kim, Saewung; Seco, Roger; Stavrakou, Trissevgeni; Longo, Karla M.; Tóta, Julio; de Souza, Rodrigo Augusto Ferreira; Vega, Oscar; Liu, Ying; Shrivastava, Manish; Alves, Eliane G.; Santos, Fernando C.; Leng, Guoyong; Hu, Zhiyuan

    2017-05-23

    Isoprene dominates global non-methane volatile organic compound emissions, and impacts tropospheric chemistry by influencing oxidants and aerosols. Isoprene emission rates vary over several orders of magnitude for different plants, and characterizing this immense biological chemodiversity is a challenge for estimating isoprene emission from tropical forests. Here we present the isoprene emission estimates from aircraft eddy covariance measurements over the Amazonian forest. We report isoprene emission rates that are three times higher than satellite top-down estimates and 35% higher than model predictions. The results reveal strong correlations between observed isoprene emission rates and terrain elevations, which are confirmed by similar correlations between satellite-derived isoprene emissions and terrain elevations. We propose that the elevational gradient in the Amazonian forest isoprene emission capacity is determined by plant species distributions and can substantially explain isoprene emission variability in tropical forests, and use a model to demonstrate the resulting impacts on regional air quality.

  19. Airborne observations reveal elevational gradient in tropical forest isoprene emissions

    Science.gov (United States)

    Gu, Dasa; Guenther, Alex B.; Shilling, John E.; Yu, Haofei; Huang, Maoyi; Zhao, Chun; Yang, Qing; Martin, Scot T.; Artaxo, Paulo; Kim, Saewung; Seco, Roger; Stavrakou, Trissevgeni; Longo, Karla M.; Tóta, Julio; de Souza, Rodrigo Augusto Ferreira; Vega, Oscar; Liu, Ying; Shrivastava, Manish; Alves, Eliane G.; Santos, Fernando C.; Leng, Guoyong; Hu, Zhiyuan

    2017-05-01

    Isoprene dominates global non-methane volatile organic compound emissions, and impacts tropospheric chemistry by influencing oxidants and aerosols. Isoprene emission rates vary over several orders of magnitude for different plants, and characterizing this immense biological chemodiversity is a challenge for estimating isoprene emission from tropical forests. Here we present the isoprene emission estimates from aircraft eddy covariance measurements over the Amazonian forest. We report isoprene emission rates that are three times higher than satellite top-down estimates and 35% higher than model predictions. The results reveal strong correlations between observed isoprene emission rates and terrain elevations, which are confirmed by similar correlations between satellite-derived isoprene emissions and terrain elevations. We propose that the elevational gradient in the Amazonian forest isoprene emission capacity is determined by plant species distributions and can substantially explain isoprene emission variability in tropical forests, and use a model to demonstrate the resulting impacts on regional air quality.

  20. A process based model for methane emission predictions from flooded rice paddies

    NARCIS (Netherlands)

    Bodegom, van P.M.; Wassmann, R.; Metra-Corton, T.M.

    2001-01-01

    Estimation and prediction of methane emission from flooded rice paddies is impaired by the large spatial and temporal variability in methane emissions and by the dynamic nonlinear relations between processes underlying methane emissions. This paper describes a process-based model on methane emission

  1. Carbon emission disclosure: does it matter

    Science.gov (United States)

    Sudibyo, Y. A.

    2018-01-01

    The purpose of this research were to test empirically the relationship of Volume of Carbon emission, Carbon Management Practice disclosure and Carbon disclosure emission with firm value, especially in Indonesia as developing Country. This research using data from Indonesian sustainability Award in 2013-2015. The instrument of this research was adapted from CDP Questionnaires to score the disclosure of Carbon Management Practice. While the carbon emission disclosure instrument was dummy variable. For volume of carbon emission, this research used the quantity or volume of carbon reported in sustainability reporting. We find that Volume of carbon emission was not related to Firm value. Also Carbon disclosure Emission does not have relationship with Firm value. Both hypotheses were not consistent with [8] which was doing their research in Developed Country. While Carbon Management Practice Disclosure, using CDP Questionnaires, has positive relationship with Firm value. The conclusion is developing country as resource constraint need to be motivated to report and disclose carbon emission from voluntary reporting to mandatory by regulation from government, not just only for high sensitive industry but also low sensitive industry. Then developing country which has resource constraint need to have more proactive strategy to prevent carbon emission instead of reducing carbon emission.

  2. Genetic Algorithm Based Microscale Vehicle Emissions Modelling

    Directory of Open Access Journals (Sweden)

    Sicong Zhu

    2015-01-01

    Full Text Available There is a need to match emission estimations accuracy with the outputs of transport models. The overall error rate in long-term traffic forecasts resulting from strategic transport models is likely to be significant. Microsimulation models, whilst high-resolution in nature, may have similar measurement errors if they use the outputs of strategic models to obtain traffic demand predictions. At the microlevel, this paper discusses the limitations of existing emissions estimation approaches. Emission models for predicting emission pollutants other than CO2 are proposed. A genetic algorithm approach is adopted to select the predicting variables for the black box model. The approach is capable of solving combinatorial optimization problems. Overall, the emission prediction results reveal that the proposed new models outperform conventional equations in terms of accuracy and robustness.

  3. Moderate emissions grandfathering

    OpenAIRE

    Knight, Carl

    2014-01-01

    Emissions grandfathering holds that a history of emissions strengthens an agent’s claim for future emission entitlements. Though grandfathering appears to have been influential in actual emission control frameworks, it is rarely taken seriously by philosophers. This article presents an argument for thinking this an oversight. The core of the argument is that members of countries with higher historical emissions are typically burdened with higher costs when transitioning to a given lower level...

  4. Ion cyclotron emission by spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Da Costa, O. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Gresillon, D. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1994-07-01

    The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs.

  5. EUVE Observations of Nonmagnetic Cataclysmic Variables

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C W

    2001-09-05

    The authors summarize EUVE's contribution to the study of the boundary layer emission of high accretion-rate nonmagnetic cataclysmic variables, especially the dwarf novae SS Cyg, U Gem, VW Hyi, and OY Car in outburst. They discuss the optical and EUV light curves of dwarf nova outbursts, the quasi-coherent oscillations of the EUV flux of SS Cyg, the EUV spectra of dwarf novae, and the future of EUV observations of cataclysmic variables.

  6. Carbon emission patterns in different income countries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai [Research Institute of Petroleum Exploration & Development, PetroChina, Beijing, 100083 (China); Yi, Wen-Jing; Zou, Le-Le [Institute of Policy and Management, Chinese Academy of Sciences, Beijing, 100190 (China); Guo, Jie; Feng, Zhen-Hua [School of Management, University of Science and Technology of China, Hefei, 230026 (China); Wei, Yi-Ming [Center for Energy and Environmental Policy Research, Beijing Institute of Technology, Beijing, 100081 (China); School of Management and Economics, Beijing Institute of Technology, Beijing, 100081 (China)

    2011-07-01

    In order to find the main driving forces affecting CO2 emission patterns and the relationship between economic development and CO2 emissions, this paper uses models of Sigma-convergence, absolute Beta-convergence and conditional Beta-convergence to analyze the inner characteristics of CO2 emissions and the income level of 128 countries (and regions) in the world. The countries (and regions) are divided into 5 groups based on their per capita income levels. The results show that in the past 40 years, all the groups showed trends of convergence on the CO2 emissions. In terms of emission levels, lagging countries (and regions) tend to catch up with advanced nations, with convergence tending to be conditional on country-specific characteristics such as energy use and energy structures rather than absolute convergence. Then this paper examines the impacts of selected variables such as GDP per capita, population, oil, gas, coal etc. on the emission trends. The analysis on the impacting factors shows that for the developing countries (and regions), the levels of economic development have greater effects on their carbon emissions patterns. And for the developed countries (and regions), the energy consumption structures wielded a big influence for the past 40 years. We find that the growth speed of CO2 emissions in developed countries (and regions) would get slower, and those of the developing countries (and regions) give expression to catching-up effects. These findings are expected to shed a light on the global policy making in coping climate change.

  7. Tropospheric Emission Spectrometer and Airborne Emission Spectrometer

    Science.gov (United States)

    Glavich, T.; Beer, R.

    1996-01-01

    The Tropospheric Emission Spectrometer (TES) is an instrument being developed for the NASA Earth Observing System Chemistry Platform. TES will measure the distribution of ozone and its precursors in the lower atmosphere. The Airborne Emission Spectrometer (AES) is an aircraft precursor to TES. Applicable descriptions are given of instrument design, technology challenges, implementation and operations for both.

  8. Atmospheric modeling to assess wind dependence in tracer dilution method measurements of landfill methane emissions.

    Science.gov (United States)

    Taylor, Diane M; Chow, Fotini K; Delkash, Madjid; Imhoff, Paul T

    2018-03-01

    The short-term temporal variability of landfill methane emissions is not well understood due to uncertainty in measurement methods. Significant variability is seen over short-term measurement campaigns with the tracer dilution method (TDM), but this variability may be due in part to measurement error rather than fluctuations in the actual landfill emissions. In this study, landfill methane emissions and TDM-measured emissions are simulated over a real landfill in Delaware, USA using the Weather Research and Forecasting model (WRF) for two emissions scenarios. In the steady emissions scenario, a constant landfill emissions rate is prescribed at each model grid point on the surface of the landfill. In the unsteady emissions scenario, emissions are calculated at each time step as a function of the local surface wind speed, resulting in variable emissions over each 1.5-h measurement period. The simulation output is used to assess the standard deviation and percent error of the TDM-measured emissions. Eight measurement periods are simulated over two different days to look at different conditions. Results show that standard deviation of the TDM- measured emissions does not increase significantly from the steady emissions simulations to the unsteady emissions scenarios, indicating that the TDM may have inherent errors in its prediction of emissions fluctuations. Results also show that TDM error does not increase significantly from the steady to the unsteady emissions simulations. This indicates that introducing variability to the landfill emissions does not increase errors in the TDM at this site. Across all simulations, TDM errors range from -15% to 43%, consistent with the range of errors seen in previous TDM studies. Simulations indicate diurnal variations of methane emissions when wind effects are significant, which may be important when developing daily and annual emissions estimates from limited field data. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature

    Directory of Open Access Journals (Sweden)

    A. Guenther

    2006-01-01

    Full Text Available Reactive gases and aerosols are produced by terrestrial ecosystems, processed within plant canopies, and can then be emitted into the above-canopy atmosphere. Estimates of the above-canopy fluxes are needed for quantitative earth system studies and assessments of past, present and future air quality and climate. The Model of Emissions of Gases and Aerosols from Nature (MEGAN is described and used to quantify net terrestrial biosphere emission of isoprene into the atmosphere. MEGAN is designed for both global and regional emission modeling and has global coverage with ~1 km2 spatial resolution. Field and laboratory investigations of the processes controlling isoprene emission are described and data available for model development and evaluation are summarized. The factors controlling isoprene emissions include biological, physical and chemical driving variables. MEGAN driving variables are derived from models and satellite and ground observations. Tropical broadleaf trees contribute almost half of the estimated global annual isoprene emission due to their relatively high emission factors and because they are often exposed to conditions that are conducive for isoprene emission. The remaining flux is primarily from shrubs which have a widespread distribution. The annual global isoprene emission estimated with MEGAN ranges from about 500 to 750 Tg isoprene (440 to 660 Tg carbon depending on the driving variables which include temperature, solar radiation, Leaf Area Index, and plant functional type. The global annual isoprene emission estimated using the standard driving variables is ~600 Tg isoprene. Differences in driving variables result in emission estimates that differ by more than a factor of three for specific times and locations. It is difficult to evaluate isoprene emission estimates using the concentration distributions simulated using chemistry and transport models, due to the substantial uncertainties in other model components, but at

  10. What Is Emissions Trading?

    Science.gov (United States)

    Learn the basics about how emissions trading uses a market-based policy tool used to control large amounts of pollution emissions from a group of sources in order to protect human health and the environment.

  11. World Emission RETRO ANTHRO

    Data.gov (United States)

    Washington University St Louis — Anthropogenic and vegetation fire emissions data were generated monthly covering a period of 1960 to 2000. Anthropogenic emissions in the RETRO inventory are derived...

  12. National Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Emission Inventory contains measured, modeled, and estimated data for emissions of all known source categories in the US (stationary sources, fires,...

  13. Emissions Modeling Clearinghouse

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Emissions Modeling Clearinghouse (EMCH) supports and promotes emissions modeling activities both internal and external to the EPA. Through this site, the EPA...

  14. Control of Emissions

    Science.gov (United States)

    Parrish, Clyde F. (Inventor); Chung, Landy (Inventor)

    2013-01-01

    Methods and apparatus utilizing chlorine dioxide and hydrogen peroxide are useful to reduce NOx emissions, as well as SOx and mercury (or other heavy metal) emissions, from combustion flue gas streams.

  15. Biodiesel Emissions Analysis Program

    Science.gov (United States)

    Using existing data, the EPA's biodiesel emissions analysis program sought to quantify the air pollution emission effects of biodiesel for diesel engines that have not been specifically modified to operate on biodiesel.

  16. Tree-mediated methane emissions along a tropical peat dome

    Science.gov (United States)

    Pangala, Sunitha; Hoyt, Alison; Cobb, Alex; Harvey, Charles; Gauci, Vincent

    2017-04-01

    Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. We examined methane emissions from all pathways including stem and leaf emissions in one of the last remaining pristine tropical peatlands in Southeast Asia: Belait peat swamp forests, Brunei Darussalam. Methane emissions along with a range of biotic and abiotic factors were measured within three 20 x 30 m plots along transects from the edge to the center of the peat done which is dominated by Shorea albida. Tree-mediated methane emissions were the dominant means of methane emissions from all three plots, with soil emissions equating to less than 30% of the total ecosystem methane flux. Both tree and soil emissions varied between and within the three plots, with soil emissions decreasing from the edge to the center of the peat dome with increasing peat depth and decreasing water table depths and tree emissions following an opposite trend. Within each plot, tree-mediated methane emissions displayed large variability with fluxes ranging between 0.2 - 9.4 mg m-2 hr-1. Relationships between tree-mediated methane emissions and pore-water methane concentrations point towards the possibility of some of these trees transporting methane produced in the deeper layers of the peat profile to the atmosphere. Taken together, these observations highlight that methane emissions through tree stems play a more central role in methane cycling in tropical peatlands.

  17. Galactic Diffuse Polarized Emission

    Indian Academy of Sciences (India)

    Diffuse polarized emission by synchrotron is a key tool to investigate magnetic fields in the Milky Way, particularly the ordered component of the large scale structure. Key observables are the synchrotron emission itself and the RM is by Faraday rotation. In this paper the main properties of the radio polarized diffuse emission ...

  18. Bridging the Emissions Gap

    NARCIS (Netherlands)

    Blok, K.

    2012-01-01

    The analyses in Chapters 2 and 3 of this report concluded that the emissions gap in 2020 will likely be between 8 and 13 GtCO2e. The chapters also estimated the difference between BaU emissions in 2020 and the emissions level consistent with a “likely” chance of staying within the 2°C target to

  19. Methane emissions from rice paddies : experiments and modelling

    OpenAIRE

    Bodegom, van, P.M.

    2000-01-01

    This thesis describes model development and experimentation on the comprehension and prediction of methane (CH 4 ) emissions from rice paddies. The large spatial and temporal variability in CH 4 emissions and the dynamic non-linear relationships between processes underlying CH 4 emissions impairs the applicability of empirical relations. Mechanistic concepts are therefore starting point of analysis throughout the th...

  20. Variable Valve Actuation

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    the mechanism it was determined that the single cam design did not have enough flexibility to satisfy three critical OEM requirements simultaneously, (maximum valve lift variation, intake valve opening timing and valve closing duration), and a new approach would be necessary. After numerous internal design reviews including several with the OEM a dual cam design was developed that had the flexibility to meet all motion requirements. The second cam added complexity to the mechanism however the cost was offset by the deletion of the electric motor required in the previous design. New patent applications including detailed drawings and potential valve motion profiles were generated and alternate two cam designs were proposed and evaluated for function, cost, reliability and durability. Hardware was designed and built and testing of sample hardware was successfully completed on an engine test stand. The mechanism developed during the course of this investigation can be applied by Original Equipment Manufacturers, (OEM), to their advanced diesel engines with the ultimate goal of reducing emissions and improving fuel economy. The objectives are: (1) Develop an optimal, cost effective, variable valve actuation (VVA) system for advanced low temperature diesel combustion processes. (2) Design and model alternative mechanical approaches and down-select for optimum design. (3) Build and demonstrate a mechanism capable of application on running engines.

  1. A whole farm model for quantifying total greenhouse gas emissions ...

    African Journals Online (AJOL)

    A whole farm model for quantifying total greenhouse gas emissions on South African dairy farms. ... South African Journal of Animal Science ... The model, which is based on a whole farm management approach, accounts for the variability that occurs in GHG emissions among farm production and management practices.

  2. Methane emissions from rice paddies : experiments and modelling

    NARCIS (Netherlands)

    Bodegom, van P.M.

    2000-01-01

    This thesis describes model development and experimentation on the comprehension and prediction of methane (CH 4 ) emissions from rice paddies. The large spatial and temporal variability in CH 4 emissions and the dynamic non-linear relationships

  3. Methane emissions in Danish riparian wetlands

    DEFF Research Database (Denmark)

    Audet, Joachim; Johansen, Jan Ravn; Andersen, Peter Mejlhede

    2013-01-01

    the spatial and temporal variability in the fluxes. Fluxes of CH4 were monitored in 12 wetland plots over a year using static chambers, yielding a dataset with more than 800 measured fluxes of CH4. Yearly emissions of CH4 ranged from −0.2 to 38.3 g CH4-C m−2 year−1, and significant effects of groundwater......The present study was conducted to (i) investigate parameters influencing the fluxes of the greenhouse gas methane (CH4) in Danish riparian wetlands with contrasting vegetation characteristics and (ii) develop models relating CH4 emissions to soil and/or vegetation parameters integrating...... CH4 emission. Both models gave reliable predictions of the yearly CH4 fluxes in riparian wetlands (modeling efficiency > 0.35). Our findings support the use of vegetation, possibly in combination with some soil parameters such as peat depth, as indicator of CH4 emission in wetlands....

  4. Fugitive Mercury Emissions From Nevada Gold Mines

    Science.gov (United States)

    Miller, M. B.; Eckley, C. S.; Gustin, M.; Marsik, F.

    2008-12-01

    Mercury (Hg) can be released from point sources at gold mines (e.g. stacks associated with ore processing facilities) as well as from diffuse fugitive sources (e.g. waste rock dumps, heap leaches, etc). Fugitive Hg emissions have not been quantified for active gold mines and as such a large knowledge gap exists concerning the magnitude of total emissions from this source type. This study measured fugitive Hg emissions from two active gold mines in Northern Nevada. To contextualize the magnitude of the mine emissions with respect to those associated with natural surfaces, data were collected from undisturbed areas near the mines that are of similar geologic character. The initial results from this project have shown that there is a large range in surface Hg concentrations and associated emissions to the atmosphere from different surface types within a mine as well as between the two mines. At both mines, the lowest surface Hg concentrations and emissions were associated with the alluvium/overburden waste rock dumps. Surface Hg concentrations and emissions at nearby undisturbed sites were of similar magnitude. Surface concentrations and emissions were substantially higher from active heap leaches. In addition to the difference in fluxes for specific materials, measured emissions must be put within the context of material spatial extent and temporal variability. Here we compare Hg emission contributions from mining and undisturbed materials as a function of space and time (diel and seasonal), and illustrate the need for collection of these types of data in order to reduce uncertainties in understanding air-surface Hg exchange.

  5. Shipping emissions in ports

    OpenAIRE

    Merk, Olaf

    2014-01-01

    Shipping emissions in ports are substantial, accounting for 18 million tonnes of CO2 emissions, 0.4 million tonnes of NOx, 0.2 million of SOx and 0.03 million tonnes of PM10 in 2011. Around 85% of emissions come from containerships and tankers. Containerships have short port stays, but high emissions during these stays. Most of CO2 emissions in ports from shipping are in Asia and Europe (58%), but this share is low compared to their share of port calls (70%). European ports have much less emi...

  6. International emissions trading

    DEFF Research Database (Denmark)

    Boom, Jan Tjeerd

    This thesis discusses the design and political acceptability of international emissions trading. It is shown that there are several designs options for emissions trading at the national level that have a different impact on output and thereby related factors such as employment and consumer prices....... The differences in impact of the design make that governments may prefer different designs of emissions trading in different situations. The thesis furthermore establishes that international emissions trading may lead to higher overall emissions, which may make it a less attractive instrument....

  7. Crank drive for variable compression ratio; Kurbeltrieb fuer variable Verdichtung

    Energy Technology Data Exchange (ETDEWEB)

    Bollig, C. [FEV Motorentechnik GmbH und Co. KG, Aachen (Germany); Habermann, K.; Marckwardt, H.; Yapici, K.I. [Technische Hochschule Aachen (Germany). Lehrstuhl fuer Angewandte Thermodynamik (LAT)

    1997-11-01

    In a research project at the Institute of Applied Thermodynamics (LAT) of the University of Aachen (RWTH) between April 1995 and October 1996, a variable compression ratio was realised on a specially prepared FEV Single Cylinder Research Engine and investigated in terms of combustion and tribological behaviour. On the basis of an invention by the FEV Motorentechnik, the variable compression ratio was realised with a variable crankdrive. This technology allows a variable compression ratio across a wide range. In combination with High Pressure Supercharging, F.E. concept for S.I. engines results in a fuel saving potential of up to 30%. Equipped with well-known Three-Way-Catalyst (TWC) technology, it is capable of meeting future low emission standards. To achieve a weight-optimised design of the conrod, FEM analyses have been conducted. The primary goal of the test bench investigation was to obtain information about the influence of the unconventional piston movement during combustion as well as about the tribological behaviour of the variable crankdrive. (orig.) [Deutsch] Innerhalb eines Forschungsprojektes am Lehrstuhl fuer Angewandte Thermodynamik der RWTH-Aachen (LAT) wurde im Zeitraum April 1995 bis Oktober 1996 ein variables Verdichtungsverhaeltnis an einem speziell praeparierten FEV-Einzylinder-Ottomotor umgesetzt und brennverfahrenstechnisch wie auch tribologisch im Pruefstandsbetrieb untersucht. Basierend auf einer Erfindung der FEV Motorentechnik wurde das veraenderliche Verdichtungsverhaeltnis mit einem variablen Kurbeltrieb realisiert. Diese Technik ermoeglicht eine Variabilitaet der Verdichtung in einem grossen Bereich. In Verbindung mit Hochaufladung kann so ein ottomotorisches Verbrauchskonzept mit einem Einsparpotential von bis zu 30% dargestellt werden, das unter Beibehaltung der {lambda}=1-Technik zukuenftige Abgasnormen erfuellen kann. Die Eignung des variablen Kurbeltriebs zur Realisierung einer veraenderlichen Verdichtung konnte in der

  8. Short-term landfill methane emissions dependency on wind.

    Science.gov (United States)

    Delkash, Madjid; Zhou, Bowen; Han, Byunghyun; Chow, Fotini K; Rella, Chris W; Imhoff, Paul T

    2016-09-01

    Short-term (2-10h) variations of whole-landfill methane emissions have been observed in recent field studies using the tracer dilution method for emissions measurement. To investigate the cause of these variations, the tracer dilution method is applied using 1-min emissions measurements at Sandtown Landfill (Delaware, USA) for a 2-h measurement period. An atmospheric dispersion model is developed for this field test site, which is the first application of such modeling to evaluate atmospheric effects on gas plume transport from landfills. The model is used to examine three possible causes of observed temporal emissions variability: temporal variability of surface wind speed affecting whole landfill emissions, spatial variability of emissions due to local wind speed variations, and misaligned tracer gas release and methane emissions locations. At this site, atmospheric modeling indicates that variation in tracer dilution method emissions measurements may be caused by whole-landfill emissions variation with wind speed. Field data collected over the time period of the atmospheric model simulations corroborate this result: methane emissions are correlated with wind speed on the landfill surface with R(2)=0.51 for data 2.5m above ground, or R(2)=0.55 using data 85m above ground, with emissions increasing by up to a factor of 2 for an approximately 30% increase in wind speed. Although the atmospheric modeling and field test are conducted at a single landfill, the results suggest that wind-induced emissions may affect tracer dilution method emissions measurements at other landfills. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Comparing emission inventories and model-ready emission datasets between Europe and North America for the AQMEII project

    Science.gov (United States)

    Pouliot, George; Pierce, Thomas; Denier van der Gon, Hugo; Schaap, Martijn; Moran, Michael; Nopmongcol, Uarporn

    2012-06-01

    This paper highlights the similarities and differences in how emission inventories and datasets were developed and processed across North America and Europe for the Air Quality Model Evaluation International Initiative (AQMEII) project and then characterizes the emissions for the two domains. We focus specifically on the creation of “model-ready” gridded emission datasets for 2006 across the two continental study domains. The practice of creating and processing the two inventories is discussed with a focus on emission factors, spatial allocation, temporal variability, speciation of PM and VOCs, and the mechanics of distributing the data and supporting emission algorithms to the modeling community. The spatial and temporal distribution on common scales is compared for the pollutants of primary concern: NOx, VOCs, SO2, PM2.5, CO, and NH3. Because of differences of population distribution, emissions across North America tend to be more heterogeneous in spatial coverage than in Europe. The temporal patterns in the estimated emissions are largely the result of assumptions used to characterize human activity, with the exception of “natural” emissions, which are modulated by meteorological variability, and emissions from large electric generating units in the U.S., which have the benefit of continuous emission monitors that provide hourly resolved profiles. Emission estimates in both study domains are challenged by several important but poorly characterized emission source sectors, notably road dust, agricultural operations, biomass burning, and road transport. Finally, this paper provides insight on the strengths and weaknesses of emission inventory preparation practices on both continents. One important outcome of this comparison of 2006 emissions between Europe and North America is the greater understanding provided into how the emission estimates developed for the AQMEII project impact regional air quality model performance.

  10. Seasonal isoprene emission rates and model comparisons using whole-tree emissions from white oak

    Science.gov (United States)

    Pier, P. A.; McDuffie, C.

    1997-10-01

    Whole-tree isoprene emission rates of a chambered white oak were measured throughout the growing season to develop a seasonal emissions model and to compare with emissions estimated using current leaf algorithms and forest canopy models. Emissions increased from mid-May to a maximum in mid-July, and the highest rates occurred late in June and throughout July. Rates decreased from early August to mid-October. A model developed to characterize the whole-tree emissions accounted for 80% of the variability of observed emissions over the growing season. Peak isoprene emissions and photosynthesis occurred at the same time, but peak emissions continued longer, suggesting that peak photosynthetic rates were not necessary for peak isoprene emissions. Measured light intensities 2 m and 3.3 m down into the tree canopy corresponded to intensities estimated by using current canopy models; however, intensities at l m were 14% lower than predicted by modeling. Measured median leaf-to-air temperature differences were 2.0°C at the canopy top and 0.5°C or less in the canopy. Median values of leaf temperatures estimated using a leaf energy balance procedure were slightly lower than air temperatures at all canopy levels, although differences were not more than 0.9°C. The most recently developed biogenic emissions model, which assumes that leaf and air temperatures are the same, predicted July whole-tree emission rates fairly closely, although high emission rates were slightly underpredicted using the model. Leaf temperature adjustments used in previous canopy models were applied to this model, and in this case, predicted rates underestimated measured rates when measured rates exceeded 80 μg C g-1 h-1.

  11. Air Emissions Factors and Quantification

    Science.gov (United States)

    Emissions factors are used in developing air emissions inventories for air quality management decisions and in developing emissions control strategies. This area provides technical information on and support for the use of emissions factors.

  12. Low Emissions Aftertreatment and Diesel Emissions Reduction

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-05-27

    Detroit Diesel Corporation (DDC) has successfully completed a five-year Low Emissions Aftertreatment and Diesel Emissions Reduction (LEADER) program under a DOE project entitled: ''Research and Development for Compression-Ignition Direct-Injection Engines (CIDI) and Aftertreatment Sub-Systems''. The objectives of the LEADER Program were to: Demonstrate technologies that will achieve future federal Tier 2 emissions targets; and Demonstrate production-viable technical targets for engine out emissions, efficiency, power density, noise, durability, production cost, aftertreatment volume and weight. These objectives were successfully met during the course of the LEADER program The most noteworthy achievements in this program are listed below: (1) Demonstrated Tier 2 Bin 3 emissions target over the FTP75 cycle on a PNGV-mule Neon passenger car, utilizing a CSF + SCR system These aggressive emissions were obtained with no ammonia (NH{sub 3}) slip and a combined fuel economy of 63 miles per gallon, integrating FTP75 and highway fuel economy transient cycle test results. Demonstrated feasibility to achieve Tier 2 Bin 8 emissions levels without active NOx aftertreatment. (2) Demonstrated Tier 2 Bin 3 emissions target over the FTP75 cycle on a light-duty truck utilizing a CSF + SCR system, synergizing efforts with the DOE-DDC DELTA program. This aggressive reduction in tailpipe out emissions was achieved with no ammonia slip and a 41% fuel economy improvement, compared to the equivalent gasoline engine-equipped vehicle. (3) Demonstrated Tier 2 near-Bin 9 emissions compliance on a light-duty truck, without active NOx aftertreatment devices, in synergy with the DOE-DDC DELTA program. (4) Developed and applied advanced combustion technologies such as ''CLEAN Combustion{copyright}'', which yields simultaneous reduction in engine out NOx and PM emissions while also improving engine and aftertreatment integration by providing favorable

  13. Trace element emissions from coal

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-09-15

    Trace elements are emitted during coal combustion. The quantity, in general, depends on the physical and chemical properties of the element itself, the concentration of the element in the coal, the combustion conditions and the type of particulate control device used, and its collection efficiency as a function of particle size. Some trace elements become concentrated in certain particle streams following combustion such as bottom ash, fly ash, and flue gas particulate matter, while others do not. Various classification schemes have been developed to describe this partitioning behaviour. These classification schemes generally distinguish between: Class 1: elements that are approximately equally concentrated in the fly ash and bottom ash, or show little or no fine particle enrichment, examples include Mn, Be, Co and Cr; Class 2: elements that are enriched in the fly ash relative to bottom ash, or show increasing enrichment with decreasing particle size, examples include As, Cd, Pb and Sb; Class 3: elements which are emitted in the gas phase (primarily Hg (not discussed in this review), and in some cases, Se). Control of class 1 trace elements is directly related to control of total particulate matter emissions, while control of the class 2 elements depends on collection of fine particulates. Due to the variability in particulate control device efficiencies, emission rates of these elements can vary substantially. The volatility of class 3 elements means that particulate controls have only a limited impact on the emissions of these elements.

  14. Characterization of gaseous pollutant and particulate matter emission rates from a commercial broiler operation part II: Correlated emission rates

    Science.gov (United States)

    Roumeliotis, Taylor S.; Dixon, Brad J.; Van Heyst, Bill J.

    2010-10-01

    Emission rates of ammonia, acid gases, inorganic aerosols, methane, and size fractionated particulate matter were measured from a commercial broiler facility. This paper discusses the statistically influential parameters on numerous pollutants' emission from a broiler chicken facility and generates emission correlations to fill data gaps and develop averaged emission factors. Live mass of the birds was commonly a significant variable to each pollutant's emission. Some variables significantly impacted the pollutants' emissions, such as litter moisture content, but were measured discretely and cannot be used for filling in data gaps. House parameter correlations were, therefore, developed using parameters measured at the facility, such as indoor temperature, relative humidity, and the live mass of the birds, and relied on the mutual behaviour of discretely measured explanatory parameters and continuously monitored confounding variables. The live mass and the difference in the indoor temperature and the house set-point temperature were the most significant variables in each pollutant's correlation. The correlations predicted each pollutants emission to within 20% (total mass basis) over most broiler production cycles. Their validation on independent datasets also successfully estimated the flocks' emissions to within 3%. Emission factors (EFs) were developed for methane, ammonia, and size fractionated particulate matter using measured data and correlated emissions to fill in data gaps. PM 10 (particulate matter ≤10 microns) EFs were estimated to be 4.6 and 5.9 g d -1 [Animal Unit, AU] -1 for five and six week production cycles, respectively. PM 2.5 (PM ≤ 2.5 microns) EFs were 0.8 and 1.4 g d -1 AU -1 for five and six week cycles, respectively. Ammonia and methane emission factors were estimated at 120.8 and 197.0 g d -1 AU -1, respectively for a five week production cycle.

  15. Impact of climate variability on tropospheric ozone

    Energy Technology Data Exchange (ETDEWEB)

    Grewe, Volker [Institut fuer Physik der Atmosphaere, DLR-Oberpfaffenhofen, 82234 Wessling (Germany)

    2007-03-01

    A simulation with the climate-chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of realistic external forcings, like observed sea surface temperatures (e.g. El Nino), major volcanic eruption, solar cycle, concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate-chemistry interactions are included, like the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning). However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NO{sub x} emissions are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early 90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere-troposphere exchange (related to Northern Hemisphere

  16. Variable importance in latent variable regression models

    NARCIS (Netherlands)

    Kvalheim, O.M.; Arneberg, R.; Bleie, O.; Rajalahti, T.; Smilde, A.K.; Westerhuis, J.A.

    2014-01-01

    The quality and practical usefulness of a regression model are a function of both interpretability and prediction performance. This work presents some new graphical tools for improved interpretation of latent variable regression models that can also assist in improved algorithms for variable

  17. Classifying variability modeling techniques

    NARCIS (Netherlands)

    Sinnema, Marco; Deelstra, Sybren

    Variability modeling is important for managing variability in software product families, especially during product derivation. In the past few years, several variability modeling techniques have been developed, each using its own concepts to model the variability provided by a product family. The

  18. VOC emissions chambers

    Data.gov (United States)

    Federal Laboratory Consortium — In order to support the development of test methods and reference materials for volatile organic compounds (VOC) emissions from building materials and furnishings,...

  19. Ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2012-01-01

    The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries...... technology is adopted quicker and that the farm has the right location. It is concluded that the new application process so far has not lived up to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely...

  20. Bridging the Emissions Gap

    OpenAIRE

    Blok, K.

    2012-01-01

    The analyses in Chapters 2 and 3 of this report concluded that the emissions gap in 2020 will likely be between 8 and 13 GtCO2e. The chapters also estimated the difference between BaU emissions in 2020 and the emissions level consistent with a “likely” chance of staying within the 2°C target to be 14 GtCO2e. This chapter explores the potential for bridging this gap using a sector policy approach. Firstly, the chapter provides a summary and update of the estimated emission reduction potential ...

  1. Outsourcing CO2 Emissions

    Science.gov (United States)

    Davis, S. J.; Caldeira, K. G.

    2009-12-01

    CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with consumption of goods and services in each country. This consumption-based emissions inventory differs from the production-based inventory because of imports and exports of goods and services that, either directly or indirectly, involved CO2 emissions. Using the latest available data and reasonable assumptions regarding trans-shipment of embodied carbon through third-party countries, we developed a global consumption-based CO2 emissions inventory and have calculated associated consumption-based energy and carbon intensities. We find that, in 2004, 24% of CO2 emissions are effectively outsourced to other countries, with much of the developed world outsourcing CO2 emissions to emerging markets, principally China. Some wealthy countries, including Switzerland and Sweden, outsource over half of their consumption-based emissions, with many northern Europeans outsourcing more than three tons of emissions per person per year. The United States is both a big importer and exporter of emissions embodied in trade, outsourcing >2.6 tons of CO2 per person and at the same time as >2.0 tons of CO2 per person are outsourced to the United States. These large flows indicate that CO2 emissions embodied in trade must be taken into consideration when considering responsibility for increasing atmospheric greenhouse gas concentrations.

  2. Measurements of N2O emissions at the landscape scale

    DEFF Research Database (Denmark)

    Schelde, Kirsten; Cellier, P.; Bertolini, T.

    2011-01-01

    Nitrous oxide emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape near Bjerringbro, Denmark, to investigate the main sources of variation...

  3. Methane emissions measured directly from grazing livestock in New Zealand

    Science.gov (United States)

    Lassey, Keith R.; Ulyatt, Marcus J.; Martin, Ross J.; Walker, Carolyn F.; David Shelton, I.

    We report measurements of methane emissions from individual ruminant livestock-both sheep and dairy cows-grazing pasture typical of New Zealand lowlands in the temperate southwest Pacific. These are the first measurements reported from grazing sheep, and among the first from grazing cattle. The measurement technique, developed at Washington State University, enables emission rates to be determined from analyses of "breath" samples collected while grazing. More than 250 measurements of daily methane emission from 50 sheep (8 months old) were made, with flock-mean emission 18.9 ± 0.8 g hd -1 d -1. Although emissions were weakly correlated with feed intake, they represented a 4.6 ± 0.1 % average loss of gross dietary energy. The corresponding mean emission based on 40 measurements of daily emissions from 10 lactating dairy cows was 263 ± 10 g hd -1 d -1, approximately 6.2% of estimated gross energy intake. A notable feature was the large inter-sheep variability in daily methane emission (factor of 1.4 range) that could not be attributed to variable intake. This would appear to suggest an appreciable diversity of methanogenetic response to digestion, and may be significant in the search for strategies to control emissions of this greenhouse gas.

  4. Air Emission Inventory for the INEEL -- 1999 Emission Report

    Energy Technology Data Exchange (ETDEWEB)

    Zohner, Steven K

    2000-05-01

    This report presents the 1999 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradionuclide emissions estimates for stationary sources.

  5. Database of emission lines

    Science.gov (United States)

    Binette, L.; Ortiz, P.; Joguet, B.; Rola, C.

    1998-11-01

    A widely accessible data bank (available through Netscape) and consiting of all (or most) of the emission lines reported in the litterature is being built. It will comprise objects as diverse as HII regions, PN, AGN, HHO. One of its use will be to define/refine existing diagnostic emission line diagrams.

  6. Uncertainties in emission inventories

    NARCIS (Netherlands)

    Aardenne, van J.A.

    2002-01-01

    Emission inventories provide information about the amount of a pollutant that is emitted to the atmosphere as a result of a specific anthropogenic or natural process at a given time or place. Emission inventories can be used for either policy or scientific purposes. For

  7. Diesel Emissions Quantifier (DEQ)

    Science.gov (United States)

    .The Diesel Emissions Quantifier (Quantifier) is an interactive tool to estimate emission reductions and cost effectiveness. Publications EPA-420-F-13-008a (420f13008a), EPA-420-B-10-035 (420b10023), EPA-420-B-10-034 (420b10034)

  8. Controlling spontaneous emission

    DEFF Research Database (Denmark)

    Lodahl, Peter

    Control over spontaneous emission of light is of great importance in quantum optics. It is essential for diverse applications such as miniature lasers, light-emitting diodes, and single-photon sources for quantum information. We present experimental studies on spontaneous emission of CdSe quantum...

  9. Observed Barium Emission Rates

    Science.gov (United States)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  10. Monitoring known X-ray magnetars for intermittent radio emission

    Science.gov (United States)

    Camilo, Fernando

    2013-10-01

    Radio emission has been detected from only four magnetars (all discovered at Parkes). This emission is transient and highly variable, and appears to share other characteristics (e.g., flat radio spectra) that distinguish it from the emission of ordinary rotation-powered pulsars. However, there is clearly some relation between the radio emission of ordinary pulsars and that sometimes displayed by these magnetically-powered neutron stars. Studying this radiation provides a new opportunity to learn more about both neutron star radio emission mechanisms and magnetars. We are limited, however, by the knowledge of only four objects in the class. Several more X-ray magnetars are known, however, a few discovered only in the past few years. We aim to search for radio emission from the 11 magnetars visible from Parkes that are not currently known to emit radio waves. For this purpose, we request 4.5 hr of telescope time once per semester.

  11. A new variable color fluorescent lamp

    Science.gov (United States)

    Bakker, Leon; Kroesen, Gerrit

    2000-10-01

    Recently, there’s a growing interest in variable colour fluorescent lamps. In the past, several options for changing the color of a fluorescent lamp were proposed. Most of these options use radio frequency or pulsed excitation of the gas discharge. By changing the electrical excitation, the electron energy distribution function changes. This causes the output spectrum of the lamp to change. A disadvantage of such a lamp is the expensive power sources that are required. We propose a new lamp with a variable color. The working principle of this lamp is based on mercury depletion in the positive column of a neon-mercury discharge. Under certain experimental conditions, this mercury depletion results in the addition of neon radiation to the emission spectrum of the lamp. We used several diagnostics to understand the mercury depletion process. We will present the results of Thomson scattering, UV absorption, spatially resolved absolute emission, and electrical measurements.

  12. Color Variable Light Source Using Electrodeless Discharge

    Science.gov (United States)

    Miki, Ryoji; Motomura, Hideki; Jinno, Masahumi; Aono, Masaharu

    Color variable pulsed Hg-Ne discharge lamp was invented and reported by Itatani's group in 1973. The color of Hg-Ne discharge was controlled by changing electron temperature by changing pulse frequency. Maya's group reported about color variable mercury fluorescent lamps using burst pulse and different type of phosphors. Kroesen's group proposed Hg-Ne color variable lamp using depletion effect. All these lamps use electrodes inside a tube. The authors propose a new type of color variable discharge lamp using inductively coupled plasma (ICP), electrodeless discharge. Color variable lamp using ICP is demonstrated. Just after starting discharge of Hg-Ne, the luminescent color of the lamp is red because of Ne emission. After that, the color changes gradually toward blue resulting from increase in mercury vapor pressure. When the color change stoppes and it is in the steady state with blue color, the color can be changed toward red by increasing input power. This is due to Ne emission resulting from increase in current density.

  13. Stable field emission from nanoporous silicon carbide

    Science.gov (United States)

    Kang, Myung-Gyu; Lezec, Henri J.; Sharifi, Fred

    2013-02-01

    We report on a new type of stable field emitter capable of electron emission at levels comparable to thermal sources. Such an emitter potentially enables significant advances in several important technologies which currently use thermal electron sources. These include communications through microwave electronics, and more notably imaging for medicine and security where new modalities of detection may arise due to variable-geometry x-ray sources. Stable emission of 6 A cm-2 is demonstrated in a macroscopic array, and lifetime measurements indicate these new emitters are sufficiently robust to be considered for realistic implementation. The emitter is a monolithic structure, and is made in a room-temperature process. It is fabricated from a silicon carbide wafer, which is formed into a highly porous structure resembling an aerogel, and further patterned into an array. The emission properties may be tuned both through control of the nanoscale morphology and the macroscopic shape of the emitter array.

  14. Carbon emissions in China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhu [Harvard Univ., Cambridge, MA (United States). Sustainability Science Program

    2016-07-01

    This study analyzes the spatial-temporal pattern and processes of China's energy-related carbon emissions. Based on extensive quantitative analysis, it outlines the character and trajectory of China's energy-related carbon emissions during the period 1995-2010, examining the distribution pattern of China's carbon emissions from regional and sectoral perspectives and revealing the driving factors of China's soaring emission increase. Further, the book investigates the supply chain carbon emissions (the carbon footprints) of China's industrial sectors. Anthropogenic climate change is one of the most serious challenges currently facing humankind. China is the world's largest developing country, top primary energy consumer and carbon emitter. Achieving both economic growth and environmental conservation is the country's twofold challenge. Understanding the status, features and driving forces of China's energy-related carbon emissions is a critical aspect of attaining global sustainability. This work, for the first time, presents both key findings on and a systematic evaluation of China's carbon emissions from energy consumption. The results have important implications for global carbon budgets and burden-sharing with regard to climate change mitigation. The book will be of great interest to readers around the world, as it addresses a topic of truly global significance.

  15. Types of biological variables.

    Science.gov (United States)

    Mayya, Shreemathi S; Monteiro, Ashma D; Ganapathy, Sachit

    2017-06-01

    Identification and description of variables used in any study is a necessary component in biomedical research. Statistical analyses rely on the type of variables that are involved in the study. In this short article, we introduce the different types of biological variables. A researcher has to be familiar with the type of variable he/she is dealing with in his/her research to decide about appropriate graphs/diagrams, summary measures and statistical analysis.

  16. Variable mechanical ventilation

    OpenAIRE

    Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini Jr.,Luiz Alberto; Friedman, Gilberto

    2017-01-01

    Objective To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Methods Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE?, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". Results A total of 36 studies were selected. ...

  17. UK emissions of the greenhouse gas nitrous oxide

    Science.gov (United States)

    Skiba, U.; Jones, S. K.; Dragosits, U.; Drewer, J.; Fowler, D.; Rees, R. M.; Pappa, V. A.; Cardenas, L.; Chadwick, D.; Yamulki, S.; Manning, A. J.

    2012-01-01

    Signatories of the Kyoto Protocol are obliged to submit annual accounts of their anthropogenic greenhouse gas emissions, which include nitrous oxide (N2O). Emissions from the sectors industry (3.8 Gg), energy (14.4 Gg), agriculture (86.8 Gg), wastewater (4.4 Gg), land use, land-use change and forestry (2.1 Gg) can be calculated by multiplying activity data (i.e. amount of fertilizer applied, animal numbers) with simple emission factors (Tier 1 approach), which are generally applied across wide geographical regions. The agricultural sector is the largest anthropogenic source of N2O in many countries and responsible for 75 per cent of UK N2O emissions. Microbial N2O production in nitrogen-fertilized soils (27.6 Gg), nitrogen-enriched waters (24.2 Gg) and manure storage systems (6.4 Gg) dominate agricultural emission budgets. For the agricultural sector, the Tier 1 emission factor approach is too simplistic to reflect local variations in climate, ecosystems and management, and is unable to take into account some of the mitigation strategies applied. This paper reviews deviations of observed emissions from those calculated using the simple emission factor approach for all anthropogenic sectors, briefly discusses the need to adopt specific emission factors that reflect regional variability in climate, soil type and management, and explains how bottom-up emission inventories can be verified by top-down modelling. PMID:22451103

  18. Addressing biogenic greenhouse gas emissions from hydropower in LCA.

    Science.gov (United States)

    Hertwich, Edgar G

    2013-09-03

    The ability of hydropower to contribute to climate change mitigation is sometimes questioned, citing emissions of methane and carbon dioxide resulting from the degradation of biogenic carbon in hydropower reservoirs. These emissions are, however, not always addressed in life cycle assessment, leading to a bias in technology comparisons, and often misunderstood. The objective of this paper is to review and analyze the generation of greenhouse gas emissions from reservoirs for the purpose of technology assessment, relating established emission measurements to power generation. A literature review, data collection, and statistical analysis of methane and CO2 emissions are conducted. In a sample of 82 measurements, methane emissions per kWh hydropower generated are log-normally distributed, ranging from micrograms to 10s of kg. A multivariate regression analysis shows that the reservoir area per kWh electricity is the most important explanatory variable. Methane emissions flux per reservoir area are correlated with the natural net primary production of the area, the age of the power plant, and the inclusion of bubbling emissions in the measurement. Even together, these factors fail to explain most of the variation in the methane flux. The global average emissions from hydropower are estimated to be 85 gCO2/kWh and 3 gCH4/kWh, with a multiplicative uncertainty factor of 2. GHG emissions from hydropower can be largely avoided by ceasing to build hydropower plants with high land use per unit of electricity generated.

  19. National Greenhouse Gas Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Greenhouse Gas Emission Inventory contains information on direct emissions of greenhouse gases as well as indirect or potential emissions of greenhouse...

  20. Managing Air Quality - Emissions Inventories

    Science.gov (United States)

    This page describes the role of emission inventories in the air quality management process, a description of how emission inventories are developed, and where U.S. emission inventory information can be found.

  1. Latent variable theory

    NARCIS (Netherlands)

    Borsboom, D.

    2008-01-01

    This paper formulates a metatheoretical framework for latent variable modeling. It does so by spelling out the difference between observed and latent variables. This difference is argued to be purely epistemic in nature: We treat a variable as observed when the inference from data structure to

  2. Amplification variable factor amplifier

    NARCIS (Netherlands)

    Akitsugu, Oshita; Nauta, Bram

    2007-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and

  3. Amplification variable factor amplifier

    NARCIS (Netherlands)

    Akitsugu, O.; Nauta, Bram

    2006-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and

  4. Global variability of cloud condensation nuclei concentrations

    Science.gov (United States)

    Makkonen, Risto; Krüger, Olaf

    2017-04-01

    Atmospheric aerosols can influence cloud optical and dynamical processes by acting as cloud condensation nuclei (CCN). Globally, these indirect aerosol effects are significant to the radiative budget as well as a source of high uncertainty in anthropogenic radiative forcing. While historically many global climate models have fixed CCN concentrations to a certain level, most state-of-the-art models calculate aerosol-cloud interactions with sophisticated methodologies based on interactively simulated aerosol size distributions. However, due to scarcity of atmospheric observations simulated global CCN concentrations remain poorly constrained. Here we assess global CCN variability with a climate model, and attribute potential trends during 2000-2010 to changes in emissions and meteorological fields. Here we have used ECHAM5.5-HAM2 with model M7 microphysical aerosol model. The model has been upgraded with a secondary organic aerosol (SOA) scheme including ELVOCs. Dust and sea salt emissions are calculated online, based on wind speed and hydrology. Each experiment is 11 years, analysed after a 6-month spin-up period. The MODIS CCN product (Terra platform) is used to evaluate model performance throughout 2000-2010. While optical remote observation of CCN column includes several deficiencies, the products serves as a proxy for changes during the simulation period. In our analysis we utilize the observed and simulated vertical column integrated CCN concentration, and limit our analysis only over marine regions. Simulated annual CCN column densities reach 2ṡ108 cm-2 near strong source regions in central Africa, Arabian Sea, Bay of Bengal and China sea. The spatial concentration gradient in CCN(0.2%) is steep, and column densities drop to <50% a few hundred kilometers away from the coasts. While the spatial distribution of CCN at 0.2% supersaturation is closer to that of MODIS proxy, as opposed to 1.0% supersaturation, the overall column integrated CCN are too low. Still

  5. Variable mechanical ventilation

    Science.gov (United States)

    Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini Jr., Luiz Alberto; Friedman, Gilberto

    2017-01-01

    Objective To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Methods Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". Results A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Conclusion Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation. PMID:28444076

  6. Variable mechanical ventilation.

    Science.gov (United States)

    Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini, Luiz Alberto; Friedman, Gilberto

    2017-01-01

    To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation.

  7. 2011 NATA - Emissions Sources

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset includes all emissions sources that were modeled in the 2011 National Air Toxics Assessment (NATA), inlcluding point, nonpoint, and mobile sources, and...

  8. National Emission Inventory (NEI)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data exchange allows states to submit data to the US Environmental Protection Agency's National Emissions Inventory (NEI). NEI is a national database of air...

  9. Air Emissions Inventories

    Science.gov (United States)

    This site provides access to emissions data, regulations and guidance, electronic system access, resources and tools to support trends analysis, regional, and local scale air quality modeling, regulatory impact assessments.

  10. Photon enhanced thermionic emission

    Science.gov (United States)

    Schwede, Jared; Melosh, Nicholas; Shen, Zhixun

    2014-10-07

    Photon Enhanced Thermionic Emission (PETE) is exploited to provide improved efficiency for radiant energy conversion. A hot (greater than 200.degree. C.) semiconductor cathode is illuminated such that it emits electrons. Because the cathode is hot, significantly more electrons are emitted than would be emitted from a room temperature (or colder) cathode under the same illumination conditions. As a result of this increased electron emission, the energy conversion efficiency can be significantly increased relative to a conventional photovoltaic device. In PETE, the cathode electrons can be (and typically are) thermalized with respect to the cathode. As a result, PETE does not rely on emission of non-thermalized electrons, and is significantly easier to implement than hot-carrier emission approaches.

  11. Discovery of a new short-period, eclipsing cataclysmic variable

    Science.gov (United States)

    Downes, R. A.; Mateo, M.; Szkody, P.; Jenner, D. C.; Margon, B.

    1986-01-01

    Photometry and spectroscopy of a newly recognized 14th mag eclipsing cataclysmic variable, KPD 1911 + 1212 (= SVS 8130, V1315 Agl) are reported. The system exhibits deep (1.7 mag) eclipses with period 0.1397 day. The spectrum is that of a high-excitation old nova and shows dramatic variability of the emission line strengths through the eclipse. The profiles of the Balmer emission lines are also phase-dependent, with prominent absorption cores appearing briefly near the inferior conjunction of the emission line source. There is no direct evidence for the secondary. A preliminary determination of radial velocity variations at modest spectral resolution yields K = 132 + or - 26 km/s for the Balmer emission lines. A model is presented for the system consistent with current data, which implies a mass for the primary and secondary stars of 0.9 and 0.4 solar mass respectively and in inclination of i = 78 deg.

  12. Highly emissive platinum(II) metallacages

    Science.gov (United States)

    Yan, Xuzhou; Cook, Timothy R.; Wang, Pi; Huang, Feihe; Stang, Peter J.

    2015-04-01

    Light-emitting materials, especially those with tunable wavelengths, attract considerable attention for applications in optoelectronic devices, fluorescent probes, sensors and so on. Many species evaluated for these purposes either emit as a dilute solution or on aggregation, with the former often self-quenching at high concentrations, and the latter falling dark when aggregation is disrupted. Here we preserve emissive behaviour at both low- and high-concentration regimes for two discrete supramolecular coordination complexes (SCCs). These tetragonal prismatic SCCs are self-assembled on mixing a metal acceptor, Pt(PEt3)2(OSO2CF3)2, with two organic donors, a pyridyl-decorated tetraphenylethylene and one of two benzene dicarboxylate species. The rigid organization of these fluorescence-active ligands imparts an emissive behaviour to dilute solutions of the resulting assemblies. Furthermore, on aggregation the prisms exhibit variable-wavelength visible-light emission, including rare white-light emission in tetrahydrofuran. The favourable photophysical properties and solvent-dependent aggregation behaviour provide a means to tune emission wavelengths.

  13. Transportation Emissions: some basics

    DEFF Research Database (Denmark)

    Kontovas, Christos A.; Psaraftis, Harilaos N.

    2016-01-01

    . The main purpose of this chapter is to introduce some basic concepts that are relevant in the quest of green transportation logistics. First, we present the basics of estimating emissions from transportation activities, the current statistics and future trends, as well as the total impact of air emissions...... of the energy efficiency gap and examines why governments and companies may forego cost-effective investments in energy efficiency, even though they could significantly reduce energy consumption at a lower cost....

  14. Nanoscale Terahertz Emission Spectroscopy

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Kim, Hyewon; Colvin, Vicki L.

    By utilizing plasmonic coupling to an AFM probe, we demonstrate Laser Terahertz Emission Nanoscopy (LTEN) with sub-20 nm resolution. We demonstrate the resolution by imaging a single gold nanorod on an InAs substrate.......By utilizing plasmonic coupling to an AFM probe, we demonstrate Laser Terahertz Emission Nanoscopy (LTEN) with sub-20 nm resolution. We demonstrate the resolution by imaging a single gold nanorod on an InAs substrate....

  15. Prediction of enteric methane emissions from cattle.

    Science.gov (United States)

    Moraes, Luis E; Strathe, Anders B; Fadel, James G; Casper, David P; Kebreab, Ermias

    2014-07-01

    Agriculture has a key role in food production worldwide and it is a major component of the gross domestic product of several countries. Livestock production is essential for the generation of high quality protein foods and the delivery of foods in regions where animal products are the main food source. Environmental impacts of livestock production have been examined for decades, but recently emission of methane from enteric fermentation has been targeted as a substantial greenhouse gas source. The quantification of methane emissions from livestock on a global scale relies on prediction models because measurements require specialized equipment and may be expensive. The predictive ability of current methane emission models remains poor. Moreover, the availability of information on livestock production systems has increased substantially over the years enabling the development of more detailed methane prediction models. In this study, we have developed and evaluated prediction models based on a large database of enteric methane emissions from North American dairy and beef cattle. Most probable models of various complexity levels were identified using a Bayesian model selection procedure and were fitted under a hierarchical setting. Energy intake, dietary fiber and lipid proportions, animal body weight and milk fat proportion were identified as key explanatory variables for predicting emissions. Models here developed substantially outperformed models currently used in national greenhouse gas inventories. Additionally, estimates of repeatability of methane emissions were lower than the ones from the literature and multicollinearity diagnostics suggested that prediction models are stable. In this context, we propose various enteric methane prediction models which require different levels of information availability and can be readily implemented in national greenhouse gas inventories of different complexity levels. The utilization of such models may reduce errors

  16. Aircraft specific exhaust emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lecht, M.; Deidewig, F.; Doepelheuer, A. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Inst. fuer Antriebstechnik

    1997-12-01

    The objective of this work to calculate essential species of aircraft emissions has been approached by a combination of different tasks. First of all engine performance and emission correlation has been modelled taking sea level static measurements from the engine certification process as a reference. At second a flight simulation program has been modified to couple aircraft and engine performance along a flight mission profile. By this for a selected number of aircraft/engine combinations the emissions of NO{sub x}, CO and HC as well as fuel burn for short, medium and long haul flights have been calculated and finally adapted to a specified format of flight distance and altitude increments. Sensitivity studies of the change of emissions along the cruise section showed a 30% decrease of the NO{sub x} emission rate until the end of cruise. Differences of ambient air temperature from ISA conditions will have a substantial impact on NO{sub x}, CO and HC emissions rather than on mission fuel. (orig.) 144 figs., 42 tabs., 497 refs.

  17. Biogenic Emission Inventories: Scaling Local Biogenic Measurements to Regions

    Science.gov (United States)

    Lamb, B.; Pressley, S.; Westberg, H.; Guenther, A.

    2002-12-01

    Biogenic Hydrocarbons, such as isoprene, are important trace gas species that are naturally emitted by vegetation and that affect the oxidative capacity of the atmosphere. Biogenic emissions are regulated by many environmental variables; the most important variables are thought to be temperature and light. Long-term isoprene flux measurements are useful for verifying existing canopy models and exploring other correlations between isoprene fluxes and environmental parameters. Biogenic Emission Models, such as BEIS (Biogenic Emission Inventory System) rely on above canopy environmental parameters and below canopy scaling factors to estimate canopy scale biogenic hydrocarbon fluxes. Other models, which are more complex, are coupled micrometeorological and physiological modules that provide feedback mechanisms present in a canopy environment. These types of models can predict biogenic emissions well, however, the required input is extensive, and for regional applications, they can be cumbersome. This paper presents analyses based on long-term isoprene flux measurements that have been collected since 1999 at the AmeriFlux site located at the University of Michigan Biological Station (UMBS) as part of the Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET). The goals of this research were to explore a potential relationship between the surface energy budget (primarily sensible heat flux) and isoprene emissions. Our hypothesis is that the surface energy flux is a better model parameter for isoprene emissions at the canopy scale than temperature and light levels, and the link to the surface energy budget will provide a significant improvement in isoprene emission models. Preliminary results indicate a significant correlation between daily isoprene emissions and sensible heat fluxes for a predominantly aspen/oak stand located in northern Michigan. Since surface energy budgets are an integral part of mesoscale meteorological models, this

  18. Intercomparison of NOx emission inventories over East Asia

    Directory of Open Access Journals (Sweden)

    J. Ding

    2017-08-01

    Full Text Available We compare nine emission inventories of nitrogen oxides including four satellite-derived NOx inventories and the following bottom-up inventories for East Asia: REAS (Regional Emission inventory in ASia, MEIC (Multi-resolution Emission Inventory for China, CAPSS (Clean Air Policy Support System and EDGAR (Emissions Database for Global Atmospheric Research. Two of the satellite-derived inventories are estimated by using the DECSO (Daily Emission derived Constrained by Satellite Observations algorithm, which is based on an extended Kalman filter applied to observations from OMI or from GOME-2. The other two are derived with the EnKF algorithm, which is based on an ensemble Kalman filter applied to observations of multiple species using either the chemical transport model CHASER and MIROC-chem. The temporal behaviour and spatial distribution of the inventories are compared on a national and regional scale. A distinction is also made between urban and rural areas. The intercomparison of all inventories shows good agreement in total NOx emissions over mainland China, especially for trends, with an average bias of about 20 % for yearly emissions. All the inventories show the typical emission reduction of 10 % during the Chinese New Year and a peak in December. Satellite-derived approaches using OMI show a summer peak due to strong emissions from soil and biomass burning in this season. Biases in NOx emissions and uncertainties in temporal variability increase quickly when the spatial scale decreases. The analyses of the differences show the importance of using observations from multiple instruments and a high spatial resolution model for the satellite-derived inventories, while for bottom-up inventories, accurate emission factors and activity information are required. The advantage of the satellite-derived approach is that the emissions are soon available after observation, while the strength of the bottom-up inventories is that they include

  19. Intercomparison of NOx emission inventories over East Asia

    Science.gov (United States)

    Ding, Jieying; Miyazaki, Kazuyuki; van der A, Ronald Johannes; Mijling, Bas; Kurokawa, Jun-ichi; Cho, SeogYeon; Janssens-Maenhout, Greet; Zhang, Qiang; Liu, Fei; Felicitas Levelt, Pieternel

    2017-08-01

    We compare nine emission inventories of nitrogen oxides including four satellite-derived NOx inventories and the following bottom-up inventories for East Asia: REAS (Regional Emission inventory in ASia), MEIC (Multi-resolution Emission Inventory for China), CAPSS (Clean Air Policy Support System) and EDGAR (Emissions Database for Global Atmospheric Research). Two of the satellite-derived inventories are estimated by using the DECSO (Daily Emission derived Constrained by Satellite Observations) algorithm, which is based on an extended Kalman filter applied to observations from OMI or from GOME-2. The other two are derived with the EnKF algorithm, which is based on an ensemble Kalman filter applied to observations of multiple species using either the chemical transport model CHASER and MIROC-chem. The temporal behaviour and spatial distribution of the inventories are compared on a national and regional scale. A distinction is also made between urban and rural areas. The intercomparison of all inventories shows good agreement in total NOx emissions over mainland China, especially for trends, with an average bias of about 20 % for yearly emissions. All the inventories show the typical emission reduction of 10 % during the Chinese New Year and a peak in December. Satellite-derived approaches using OMI show a summer peak due to strong emissions from soil and biomass burning in this season. Biases in NOx emissions and uncertainties in temporal variability increase quickly when the spatial scale decreases. The analyses of the differences show the importance of using observations from multiple instruments and a high spatial resolution model for the satellite-derived inventories, while for bottom-up inventories, accurate emission factors and activity information are required. The advantage of the satellite-derived approach is that the emissions are soon available after observation, while the strength of the bottom-up inventories is that they include detailed information of

  20. Ferroelectric emission studies for electron emission lithography applications.

    Science.gov (United States)

    Yoo, In K; Ryu, Sang O; Suchicital, Carlos T A; Lee, June K; Kim, Byong M; Chung, Chee W

    2003-10-01

    Ferroelectric switching emission, dielectric switching emission, and pyroelectric emission were studied by patterning images on electron resist for electron emission lithography applications. It was observed that the pyroelectric emission is most acceptable for a high throughput 1:1 electron projection lithography application. A 1:1 electron projection lithography was demonstrated by patterning images with line widths of 30 microm and using pyroelectric emission. A degradation of the pyroelectric emission property of the material was observed during repeated heating cycles below the phase-transition temperature of the ferroelectric material. Annealing excursions above the phase transition temperature prevented the degradation of the pyroelectric emitter.

  1. Nitrous oxide emissions from a beech forest floor measured by eddy covariance and soil enclosure techniques

    DEFF Research Database (Denmark)

    Pihlatie, M.; Rinne, J.; Ambus, P.

    2005-01-01

    Spring time nitrous oxide (N2O) emissions from an old beech (Fagus sylvatica L.) forest were measured with eddy covariance (EC) and chamber techniques. The aim was to obtain information on the spatial and temporal variability in N2O emissions and link the emissions to soil environmental parameters...... the first week of May when the trees were leafing and the soil moisture content was at its highest. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placement of the chambers should be considered carefully to cover the spatial variability in the soil N2O emissions....... Mean N2O fluxes over the five week measurement period were 5.6 +/- 1.1, 10 +/- 1 and 16 +/- 11 mu g N m(-2) h(-1) from EC, automatic chamber and manual chambers, respectively. High temporal variability characterized the EC fluxes in the trunk-space. To reduce this variability, resulting mostly from...

  2. Emissions trading: principles and practice

    National Research Council Canada - National Science Library

    Tietenberg, Thomas H

    2006-01-01

    ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 The Evolution of Emissions Trading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 The Evolution of Design Features...

  3. The nebular variables

    CERN Document Server

    Glasby, John S

    1974-01-01

    The Nebular Variables focuses on the nebular variables and their characteristics. Discussions are organized by type of nebular variable, namely, RW Aurigae stars, T Orionis stars, T Tauri stars, and peculiar nebular objects. Topics range from light variations of the stars to their spectroscopic and physical characteristics, spatial distribution, interaction with nebulosity, and evolutionary features. This volume is divided into four sections and consists of 25 chapters, the first of which provides general information on nebular variables, including their stellar associations and their classifi

  4. Clinical and acoustical variability in hypokinetic dysarthria

    Energy Technology Data Exchange (ETDEWEB)

    Metter, E.J.; Hanson, W.R.

    1986-10-01

    Ten male patients with parkinsonism secondary to Parkinson's disease or progressive supranuclear palsy had clinical neurological, speech, and acoustical speech evaluations. In addition, seven of the patients were evaluated by x-ray computed tomography (CT) and (F-18)-fluorodeoxyglucose (FDG) positron emission tomography (PET). Extensive variability of speech features, both clinical and acoustical, were found and seemed to be independent of the severity of any parkinsonian sign, CT, or FDG PET. In addition, little relationship existed between the variability across each measured speech feature. What appeared to be important for the appearance of abnormal acoustic measures was the degree of overall severity of the dysarthria. These observations suggest that a better understanding of hypokinetic dysarthria may result from more extensive examination of the variability between patients. Emphasizing a specific feature such as rapid speaking rate in characterizing hypokinetic dysarthria focuses on a single and inconstant finding in a complex speech pattern.

  5. Impact of Biogas Stations on CO2 Emission from Agriculture

    Directory of Open Access Journals (Sweden)

    Josef Slaboch

    2017-01-01

    Full Text Available This paper deals with the effects of biogas stations on CO2 emissions produced within agricultural sector. In last years, owing to a positive policy of renewable energy resources a number of biogas stations in the CR has rapidly increased – actually over 350 agricultural biogas stations with the total installed power 365 MW are in operation. Concerning CO2 emissions from the agricultural sector, there is a presumption of decrease in produced emissions owing to decrease of influence of animal wastes which are processed just in the biogas stations. From the results it is obvious that CO2 emissions produced by agriculture in the CR decrease by 93.7 thousand tonnes annually. A presumption P1 that building of biogas stations will further support this trend is documented with results of a simple dynamic linear regression model. Further, elasticities of particular variables influencing the total emission from agriculture are investigated in the paper.

  6. Multiwavelength Variability Analysis of 3C 279

    Directory of Open Access Journals (Sweden)

    Víctor M. Patiño-Álvarez

    2017-11-01

    Full Text Available We present a multifrequency analysis of the variability in the flat-spectrum radio quasar 3C 279 from 2008 to 2014. Our multiwavelength datasets range from 1 mm to gamma-rays, with additional optical polarimetry. Cross-correlation analysis shows a significant correlation between the UV continuum emission, the optical and NIR bands, at a delay consistent with zero, implying co-spatial emission regions. We also find a correlation between the UV continuum and the 1 mm data, which implies that the dominant process in producing the UV continuum is synchrotron emission. Based on the behavior of the gamma-ray light curve with respect to other bands, we identified three different activity periods. During period A we find a significant correlation at zero delay between the UV continuum and the gamma-rays, implying co-spatial emission regions which points toward synchrotron self-Compton as dominant gamma-ray emission mechanism. During period C we find a delay between the UV continuum and the gamma-rays, as well as a correlation at zero delay between X-rays and gamma-rays, both results implying that external inverse Compton is the dominant gamma-ray emission mechanism. During period B there are multiple flares in the bands from 1 mm to UV, however, none of these show a counterpart in the gamma-rays band. We propose that this is caused by an increase in the gamma-ray opacity due to electron-positron pair production.

  7. Inhomogeneity of methane emissions from a dairy waste lagoon.

    Science.gov (United States)

    Grant, Richard H; Boehm, Matthew T

    2015-11-01

    Methane (CH4) is the dominant greenhouse gas emitted by animal agriculture manure. Since the gas is relatively insoluble in water, it is concentrated in discrete bubbles that rise through waste lagoons and burst at the surface. This results in lagoon emissions that are inhomogeneous in both space and time. Emissions from a midwestern dairy waste lagoon were measured over 2 weeks to evaluate the spatial homogeneity of the source emissions and to compare two methods for measuring this inhomogeneous emission. Emissions were determined using an inverse dispersion model based on CH4 concentrations measured both by a single scanning tunable diode laser (TDL) aimed at a series of reflectors and by flame ionization detection (FID) gas chromatography on line-sampled air. Emissions were best estimated using scanned TDL concentrations over relatively short optical paths that collectively span the entire cross-wind width of the source, so as to provide both the best capture of discrete plumes from the bursting bubbles on the lagoon surface and the best detection of CH4 background concentrations. The lagoon emissions during the study were spatially inhomogeneous at hourly time scales. Partitioning the inhomogeneous source into two source regions reduced the estimated emissions of the overall lagoon by 57% but increased the variability. Consequently, it is important to assess the homogeneity of a source prior to measurements and final emissions calculation. Plans for measuring methane emissions from waste lagoons must take into account the spatial inhomogeneity of the source strength. The assumption of emission source homogeneity for a low-solubility gas such as CH4 emitted from an animal waste lagoon can result in significant emission overestimates. The entire breadth and length of the area source must be measured, preferably with multiple optical paths, for the detection of discrete plumes from the different emitting regions and for determining the background concentration

  8. Air emissions due to wind and solar power.

    Science.gov (United States)

    Katzenstein, Warren; Apt, Jay

    2009-01-15

    Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve approximately 80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30-50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability.

  9. Mid-Infrared Variability of AGN

    Science.gov (United States)

    Rieke, George; Hines, Dean; Neugebauer, Gerry; Rigby, Jane; Shi, Yong; Smith, Paul

    2007-05-01

    Several issues dealing with the nature of flux variations of active galactic nuclei (AGN) in the thermal infrared remain unresolved after decades of investigation. Resolving the existing ambiguities will yield invaluable information concerning the physical processes important in these objects and the size of the region responsible for the IR continuum. Two sources of emission can dominate in the mid-infrared and provide a large fraction of the bolometric luminosity of AGN: (1) Synchrotron light is important for radio-loud AGN, and is generally observed to be highly variable at other wavelengths. (2) Thermal radiation from warm dust close to the central engine produces an enormous IR signature in many AGN and is likely to be dominant for radio-quiet AGN. We propose to re-observe a large sample of AGN of various types that have been measured at 24 microns by Spitzer during earlier observing cycles to identify variable objects. The stability of the well-characterized MIPS 24-micron channel, allow for the detection of <2-3% variations in the flux relative to the earlier MIPS measurements over a time scale 1-4 yr. Detection of flux variations at 24 microns identify nonthermal sources of IR emission given that changes in thermal emission sources occur over much longer time scales. Sizable radio-loud and radio-quiet subsamples are selected for systematic comparison.

  10. INTER-EXAMINER VARIABILITY

    African Journals Online (AJOL)

    Background: The traditional clinical examination has fallen into disfavour on account of considerable inter-examiner variability. The OSCE is gaining popularity as it is perceived to be less prone to this. Objective: To establish whether inter-examiner variability is still a significant factor for the undergraduate orthopaedic ...

  11. Software variability management

    NARCIS (Netherlands)

    Bosch, J; Nord, RL

    2004-01-01

    During recent years, the amount of variability that has to be supported by a software artefact is growing considerably and its management is evolving into a major challenge during development, usage, and evolution of software artefacts. Successful management of variability in software leads to

  12. Microinertia and internal variables

    CERN Document Server

    Berezovski, A

    2015-01-01

    The origin of microinertia of micromorphic theories is investigated from the point of view of non-equilibrium thermodynamics. In the framework of dual internal variables microinertia stems from a thermodynamic equation of state related to the internal variable with the properties of mechanical momentum.

  13. Variable volume combustor

    Science.gov (United States)

    Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul

    2017-01-17

    The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.

  14. Practical acoustic emission testing

    CERN Document Server

    2016-01-01

    This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.

  15. Climate variability and change

    CERN Document Server

    Grassl, H

    1998-01-01

    Many factors influence climate. The present knowledge concerning the climate relevance of earth orbital parameters, solar luminosity, volcanoes, internal interactions, and human activities will be reported as well as the vulnerability of emission scenarios for given stabilization goals for greenhouse gas concentrations and the main points of the Kyoto Protocol

  16. Field emission electronics

    CERN Document Server

    Egorov, Nikolay

    2017-01-01

    This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.

  17. Trend Prediction and Decomposed Driving Factors of Carbon Emissions in Jiangsu Province during 2015–2020

    Directory of Open Access Journals (Sweden)

    Decai Tang

    2016-10-01

    Full Text Available According to the economic and energy consumption statistics in Jiangsu Province, we combined the GM (1, 1 grey model and polynomial regression to forecast carbon emissions. Historical and projected emissions were decomposed using the Logarithmic Mean Divisia Index (LMDI approach to assess the relative contribution of different factors to emission variability. The results showed that carbon emissions will continue to increase in Jiangsu province during 2015–2020 period and cumulative carbon emissions will increase by 39.5487 million tons within the forecast period. The growth of gross domestic product (GDP per capita plays the greatest positive role in driving carbon emission growth. Furthermore, the improvement of energy usage efficiency is the primary factor responsible for reducing carbon emissions. Factors of population, industry structure adjustment and the optimization of fuel mix also help to reduce carbon emissions. Based on the LMDI analysis, we provide some advice for policy-makers in Jiangsu and other provinces in China.

  18. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  19. Methane emissions from ruminants

    African Journals Online (AJOL)

    user

    2011-02-21

    Feb 21, 2011 ... Livestock account for 35-40% of global anthropogenic emissions of methane, via enteric fermentation and manure, ... on the climate; the global warming potential of methane is. 21-times that of CO2 over 100 years ... cell wall structure from true rumen bacteria (Woese et al.1990). METHANE MITIGATION ...

  20. Reaching peak emissions

    OpenAIRE

    Jackson, Robert B.; Canadell, Josep G.; Le Quere, Corinne; Andrew, Robbie; Korsbakken, Jan Ivar; Peters, Glen P; Nakicenovic, Nebojsa

    2016-01-01

    Rapid growth in global CO2 emissions from fossil fuels and industry ceased in the past two years, despite continued economic growth. Decreased coal use in China was largely responsible, coupled with slower global growth in petroleum and faster growth in renewables.

  1. Eternity Variables to Simulate Specifications

    NARCIS (Netherlands)

    Hesselink, WH; Boiten, EA; Moller, B

    2002-01-01

    Simulation of specifications is introduced as a unification and generalization of refinement mappings, history variables, forward simulations, prophecy variables, and backward simulations. Eternity variables are introduced as a more powerful alternative for prophecy variables and backward

  2. Methane emission by camelids.

    Science.gov (United States)

    Dittmann, Marie T; Runge, Ullrich; Lang, Richard A; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

  3. Methane emission by camelids.

    Directory of Open Access Journals (Sweden)

    Marie T Dittmann

    Full Text Available Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total, all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹ when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹. However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants. This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

  4. Methane Emission by Camelids

    Science.gov (United States)

    Dittmann, Marie T.; Runge, Ullrich; Lang, Richard A.; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg−1 d−1) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg−1 d−1). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg−1 in camelids vs. 86.2±12.1 L kg−1 in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels. PMID:24718604

  5. Cigar burning under different smoking intensities and effects on emissions.

    Science.gov (United States)

    Dethloff, Ole; Mueller, Christian; Cahours, Xavier; Colard, Stéphane

    2017-10-24

    The effect of smoking intensity on cigar smoke emissions was assessed under a range of puff frequencies and puff volumes. In order to potentially reduce emissions variability and to identify patterns as accurately as possible, cigar weights and diameters were measured, and outliers were excluded prior to smoking. Portions corresponding to 25%, 50%, 75% and 100% of the cigar, measured down to the butt length, were smoked under several smoking conditions, to assess nicotine, CO and water yields. The remaining cigar butts were analysed for total alkaloids, nicotine, and moisture. Results showed accumulation effects during the burning process having a significant impact on smoke emission levels. Condensation and evaporation occur and lead to smoke emissions dependent on smoking intensity. Differences were observed for CO on one side as a gas phase compound and nicotine on the other side as a particulate phase compound. For a given intensity, while CO emission increases linearly as the cigar burns, nicotine and water emissions exhibited an exponential increase. Our investigations showed that a complex phenomena occurs during the course of cigar smoking which makes emission data: difficult to interpret, is potentially misleading to the consumer, and inappropriate for exposure assessment. The results indicate that, tobacco content and physical parameters may well be the most robust basis for product characterisation and comparison rather than smoke emission. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Exposure to motor vehicle emissions: An intake fraction approach

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Julian D. [Univ. of California, Berkeley, CA (United States)

    2002-05-22

    Motor vehicles are a significant source of population exposure to air pollution. Focusing on California's South Coast Air Basin as a case study, the author combines ambient monitoring station data with hourly time-activity patterns to determine the population intake of motor vehicle emissions during 1996-1999. Three microenvironments are considered wherein the exposure to motor vehicle emissions is higher than in ambient air: in and near vehicles, inside a building that is near a freeway, and inside a residence with an attached garage. Total motor vehicle emissions are taken from the EMFAC model. The 15 million people in the South Coast inhale 0.0048% of primary, nonreactive compounds emitted into the basin by motor vehicles. Intake of motor vehicle emissions is 46% higher than the average ambient concentration times the average breathing rate, because of microenvironments and because of temporal and spatial correlation among breathing rates, concentrations, and population densities. Intake fraction (iF) summarizes the emissions-to-intake relationship as the ratio of population intake to total emissions. iF is a population level exposure metric that incorporates spatial, temporal, and interindividual variability in exposures. iFs can facilitate the calculation of population exposures by distilling complex emissions-transport-receptor relationships. The author demonstrates this point by predicting the population intake of various primary gaseous emissions from motor vehicles, based on the intake fraction for benzene and carbon monoxide.

  7. Variable-Rate Premiums

    Data.gov (United States)

    Pension Benefit Guaranty Corporation — These interest rates are used to value vested benefits for variable rate premium purposes as described in PBGC's regulation on Premium Rates (29 CFR Part 4006) and...

  8. Software Testing Requires Variability

    DEFF Research Database (Denmark)

    Christensen, Henrik Bærbak

    2003-01-01

    Software variability is the ability of a software system or artefact to be changed, customized or configured for use in a particular context. Variability in software systems is important from a number of perspectives. Some perspectives rightly receive much attention due to their direct economic i...... impact in software production. As is also apparent from the call for papers these perspectives focus on qualities such as reuse, adaptability, and maintainability.......Software variability is the ability of a software system or artefact to be changed, customized or configured for use in a particular context. Variability in software systems is important from a number of perspectives. Some perspectives rightly receive much attention due to their direct economic...

  9. Variable Attitude Test Stand

    Data.gov (United States)

    Federal Laboratory Consortium — The Variable Attitude Test Stand designed and built for testing of the V-22 tilt rotor aircraft propulsion system, is used to evaluate the effect of aircraft flight...

  10. Calculus of one variable

    CERN Document Server

    Grossman, Stanley I

    1986-01-01

    Calculus of One Variable, Second Edition presents the essential topics in the study of the techniques and theorems of calculus.The book provides a comprehensive introduction to calculus. It contains examples, exercises, the history and development of calculus, and various applications. Some of the topics discussed in the text include the concept of limits, one-variable theory, the derivatives of all six trigonometric functions, exponential and logarithmic functions, and infinite series.This textbook is intended for use by college students.

  11. Anthropogenic mercury emission inventory with emission factors and total emission in Korea

    Science.gov (United States)

    Kim, Jeong-Hun; Park, Jung-Min; Lee, Sang-Bo; Pudasainee, Deepak; Seo, Yong-Chil

    2010-07-01

    Mercury emissions concentrations, emission factors, and the total national emission from major anthropogenic sources in Korea for the year 2007 were estimated. Uncontrolled and controlled mercury emission factors and the total emission from each source types are presented. The annual national mercury emission from major anthropogenic sources for the year 2007, on average was 12.8 ton which ranged from 6.5 to 20.2 ton. Averaged emissions of elemental, oxidized, and particulate mercury were estimated at 8.25 ton, 3.69 ton, and 0.87 ton, respectively. Due to the removal of a major portion of particulate and oxidized mercury species, elemental mercury was dominant in stack emission. About 54.8% of mercury emission was contributed by industrial sources, 45.0% by stationary combustion sources and 0.02% by mobile sources. Thermal power plants, oil refineries, cement kilns and incinerators (municipal, industrial, medical, sewage sludge) were the major mercury emitters, contributing about 26%, 25%, 21% and 20%, respectively to the total mercury emission. Other sources (crematory, pulp and paper manufacturing, nonferrous metals manufacturing, glass manufacturing) contributed about 8% of the total emission. Priority should be given in controlling mercury emissions from coal-fired power plants, oil refineries, cement kilns and waste incinerators. More measurements including natural and re-emission sources are to be carried out in the future in order to have a clear scenario of mercury emission from the country and to apply effective control measures.

  12. Carbon emissions performance of commercial logging in East Kalimantan, Indonesia.

    Science.gov (United States)

    Griscom, Bronson; Ellis, Peter; Putz, Francis E

    2014-03-01

    Adoption of reduced-impact logging (RIL) methods could reduce CO2 emissions by 30-50% across at least 20% of remaining tropical forests. We developed two cost effective and robust indices for comparing the climate benefits (reduced CO2 emissions) due to RIL. The indices correct for variability in the volume of commercial timber among concessions. We determined that a correction for variability in terrain slope was not needed. We found that concessions certified by the Forest Stewardship Council (FSC, N = 3), when compared with noncertified concessions (N = 6), did not have lower overall CO2 emissions from logging activity (felling, skidding, and hauling). On the other hand, FSC certified concessions did have lower emissions from one type of logging impact (skidding), and we found evidence of a range of improved practices using other field metrics. One explanation of these results may be that FSC criteria and indicators, and associated RIL practices, were not designed to achieve overall emissions reductions. Also, commonly used field metrics are not reliable proxies for overall logging emissions performance. Furthermore, the simple distinction between certified and noncertified concessions does not fully represent the complex history of investments in improved logging practices. To clarify the relationship between RIL and emissions reductions, we propose the more explicit term 'RIL-C' to refer to the subset of RIL practices that can be defined by quantified thresholds and that result in measurable emissions reductions. If tropical forest certification is to be linked with CO2 emissions reductions, certification standards need to explicitly require RIL-C practices. © 2013 John Wiley & Sons Ltd.

  13. Odour emissions from poultry litter - A review litter properties, odour formation and odorant emissions from porous materials.

    Science.gov (United States)

    Dunlop, Mark W; Blackall, Patrick J; Stuetz, Richard M

    2016-07-15

    Odour emissions from meat chicken sheds can at times cause odour impacts on surrounding communities. Litter is seen as the primary source of this odour. Formation and emission of odour from meat chicken litter during the grow-out period are influenced by various factors such as litter conditions, the environment, microbial activity, properties of the odorous gases and management practices. Odour emissions vary spatially and temporally. This variability has made it challenging to understand how specific litter conditions contribute to odour emissions from the litter and production sheds. Existing knowledge on odorants, odour formation mechanisms and emission processes that contribute to odour emissions from litter are reviewed. Litter moisture content and water thermodynamics (i.e. water activity, Aw) are also examined as factors that contribute to microbial odour formation, physical litter conditions and the exchange of individual odorant gases at the air-water interface. Substantial opportunities exist for future research on litter conditions and litter formation mechanisms and how these contribute to odour emissions. Closing this knowledge gap will improve management strategies that intercept and interfere with odour formation and emission processes leading to an overall reduction in the potential to cause community impacts. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  14. Estimating Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Jørgensen, Morten W.; Sorenson, Spencer C.

    1998-01-01

    Several parameters of importance for estimating emissions from railway traffic are discussed, and typical results presented. Typical emissions factors from diesel engines and electrical power generation are presented, and the effect of differences in national electrical generation sources...

  15. Carbon emission flow in networks

    National Research Council Canada - National Science Library

    Kang, Chongqing; Zhou, Tianrui; Chen, Qixin; Xu, Qianyao; Xia, Qing; Ji, Zhen

    2012-01-01

    As the human population increases and production expands, energy demand and anthropogenic carbon emission rates have been growing rapidly, and the need to decrease carbon emission levels has drawn increasing attention...

  16. Phenomenology of magnetospheric radio emissions

    Science.gov (United States)

    Carr, T. D.; Desch, M. D.; Alexander, J. K.

    1983-01-01

    Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.

  17. Danish emission inventories for agriculture

    DEFF Research Database (Denmark)

    Mikkelsen, Mette Hjorth; Albrektsen, Rikke; Gyldenkærne, Steen

    . This report contains a description of the emissions from the agricultural sector from 1985 to 2009. Furthermore, the report includes a detailed description of methods and data used to calculate the emissions, which is based on national methodologies as well as international guidelines. For the Danish...... emissions calculations and data management an Integrated Database model for Agricultural emissions (IDA) is used. The emission from the agricultural sector includes emission of the greenhouse gases methane (CH4), nitrous oxide (N2O), ammonia (NH3), particulate matter (PM), non-methane volatile organic...... compounds (NMVOC) and other pollutants related to the field burning of agricultural residue such as NOx, CO2, CO, SO2, heavy metals, dioxin and PAH. The ammonia emission from 1985 to 2009 has decreased from 119 300 tonnes of NH3 to 73 800 tonnes NH3, corresponding to a 38 % reduction. The emission...

  18. Spectral Variability in Radio-Loud Quasars Minfeng Gu

    Indian Academy of Sciences (India)

    when-brighter trend, which is in contrast to our previous results. Eight of 18 SSRQs display a BWB. We found an anticorrelation between the. Eddington ratio and the variability amplitude in the r band for SSRQs, which is similar to that in radio-quiet AGNs. This implies that the thermal emission from the accretion disk may be ...

  19. Future Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Sorenson, Spencer C.

    1998-01-01

    In investigation of the expected development in factors which influence railway energy consumption and emissions. Traffic factors such as train speed, load, an occupancy were considered. Tehcnical factors such an emissions factors, fleet composition and train weight were also considered. An estim......In investigation of the expected development in factors which influence railway energy consumption and emissions. Traffic factors such as train speed, load, an occupancy were considered. Tehcnical factors such an emissions factors, fleet composition and train weight were also considered...

  20. Field Emission in Vacuum Microelectronics

    CERN Document Server

    Fursey, George; Schwoebel, Paul

    2005-01-01

    Field emission is a phenomenon described by quantum mechanics. Its emission capability is millions times higher than that of any other known types of electron emission. Nowadays this phenomenon is experiencing a new life due to wonderful applications in the atomic resolution microscopy, in electronic holography, and in the vacuum micro- and nanoelectronics in general. The main field emission properties, and some most remarkable experimental facts and applications, are described in this book.

  1. Global emissions inventories

    Energy Technology Data Exchange (ETDEWEB)

    Dignon, J.

    1995-07-01

    Atmospheric chemistry determines the concentrations of most of the important greenhouse gases except for carbon dioxide. The rate of removal of the greenhouse gases from the atmosphere is also controlled by atmospheric chemistry. The indirect effects of chemical forcing resulting from the chemical interactions of other species can also affect the concentrations of radiatively important gases such as ozone. In order to establish the contribution of any possible climatic change attributable to individual greenhouse gases, spatially and temporally resolved estimates of their emissions need to be established. Unfortunately, for most of the radiatively important species the global magnitudes of their individual fluxes are not known to better than a factor of two and their spatial distributions are even more poorly characterized. Efforts to estimate future projections of potential impacts and to monitor international agreements will require continued research to narrow the uncertainties of magnitude and geographical distribution of emissions.

  2. Forecasting carbon dioxide emissions.

    Science.gov (United States)

    Zhao, Xiaobing; Du, Ding

    2015-09-01

    This study extends the literature on forecasting carbon dioxide (CO2) emissions by applying the reduced-form econometrics approach of Schmalensee et al. (1998) to a more recent sample period, the post-1997 period. Using the post-1997 period is motivated by the observation that the strengthening pace of global climate policy may have been accelerated since 1997. Based on our parameter estimates, we project 25% reduction in CO2 emissions by 2050 according to an economic and population growth scenario that is more consistent with recent global trends. Our forecasts are conservative due to that we do not have sufficient data to fully take into account recent developments in the global economy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Final Report GlobEmission

    NARCIS (Netherlands)

    2016-01-01

    At the origin of all air quality issues are the emissions of pollutants. Emission inventories provide essential information on magnitude, type of activity, time evolution and the spatial coverage of the emissions. These inventories are developed for use by the policy makers in order to evaluate

  4. Power plant emissions reduction

    Science.gov (United States)

    Anand, Ashok Kumar; Nagarjuna Reddy, Thirumala Reddy

    2015-10-20

    A system for improved emissions performance of a power plant generally includes an exhaust gas recirculation system having an exhaust gas compressor disposed downstream from the combustor, a condensation collection system at least partially disposed upstream from the exhaust gas compressor, and a mixing chamber in fluid communication with the exhaust gas compressor and the condensation collection system, where the mixing chamber is in fluid communication with the combustor.

  5. Acoustic emission source modeling

    Directory of Open Access Journals (Sweden)

    Hora P.

    2010-07-01

    Full Text Available The paper deals with the acoustic emission (AE source modeling by means of FEM system COMSOL Multiphysics. The following types of sources are used: the spatially concentrated force and the double forces (dipole. The pulse excitation is studied in both cases. As a material is used steel. The computed displacements are compared with the exact analytical solution of point sources under consideration.

  6. Methane emission by Camelids

    OpenAIRE

    Marie T Dittmann; Runge, Ullrich; Lang, Richard A.; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large pop...

  7. Efficient emissions reduction

    OpenAIRE

    Roussillon, Beatrice; Schweinzer, Paul

    2010-01-01

    We propose a simple mechanism capable of achieving international agreement on the reduction of harmful emissions to their efficient level. It employs a contest creating incentives among participating nations to simultaneously exert efficient productive and efficient abatement efforts. Participation in the most stylised formulation of the scheme is voluntary and individually rational. All rules are mutually agreeable and are unanimously adopted if proposed. The scheme balances its budget and r...

  8. Neuroanatomical variability of religiosity.

    Science.gov (United States)

    Kapogiannis, Dimitrios; Barbey, Aron K; Su, Michael; Krueger, Frank; Grafman, Jordan

    2009-09-28

    We hypothesized that religiosity, a set of traits variably expressed in the population, is modulated by neuroanatomical variability. We tested this idea by determining whether aspects of religiosity were predicted by variability in regional cortical volume. We performed structural magnetic resonance imaging of the brain in 40 healthy adult participants who reported different degrees and patterns of religiosity on a survey. We identified four Principal Components of religiosity by Factor Analysis of the survey items and associated them with regional cortical volumes measured by voxel-based morphometry. Experiencing an intimate relationship with God and engaging in religious behavior was associated with increased volume of R middle temporal cortex, BA 21. Experiencing fear of God was associated with decreased volume of L precuneus and L orbitofrontal cortex BA 11. A cluster of traits related with pragmatism and doubting God's existence was associated with increased volume of the R precuneus. Variability in religiosity of upbringing was not associated with variability in cortical volume of any region. Therefore, key aspects of religiosity are associated with cortical volume differences. This conclusion complements our prior functional neuroimaging findings in elucidating the proximate causes of religion in the brain.

  9. Classifying TDSS Stellar Variables

    Science.gov (United States)

    Amaro, Rachael Christina; Green, Paul J.; TDSS Collaboration

    2017-01-01

    The Time Domain Spectroscopic Survey (TDSS), a subprogram of SDSS-IV eBOSS, obtains classification/discovery spectra of point-source photometric variables selected from PanSTARRS and SDSS multi-color light curves regardless of object color or lightcurve shape. Tens of thousands of TDSS spectra are already available and have been spectroscopically classified both via pipeline and by visual inspection. About half of these spectra are quasars, half are stars. Our goal is to classify the stars with their correct variability types. We do this by acquiring public multi-epoch light curves for brighter stars (rclassifications and parameters in the Catalina Surveys Periodic Variable Star Catalog. Variable star classifications include RR Lyr, close eclipsing binaries, CVs, pulsating white dwarfs, and other exotic systems. The key difference between our catalog and others is that along with the light curves, we will be using TDSS spectra to help in the classification of variable type, as spectra are rich with information allowing estimation of physical parameters like temperature, metallicity, gravity, etc. This work was supported by the SDSS Research Experience for Undergraduates program, which is funded by a grant from Sloan Foundation to the Astrophysical Research Consortium.

  10. X-Ray variability in LINERs

    Science.gov (United States)

    Hernández-García, L.; González-Martín, O.; Masegosa, J.; Márquez, I.

    2013-05-01

    Active galactic nuclei (AGN) are powered by energetic phenomena which cannot be attributed to stars. Among AGN, several objects can be described by the unified model (Antonucci 1993; Urry & Padovani 1995). However, several subclasses of objects that cannot be accommodated into this scheme, as is the case of LINERs (low ionisation narrow emission line regions). Variability across the whole electromagnetic spectrum is one of the properties that characterized AGNs. Therefore, searching for variability in LINERs could unequivocally demonstrate the presence of a non-thermal source. Also, X-rays is one of the best ways to search for AGN signature. In this work (which is part of a larger study) we add more evidence about the X-ray variability in LINERs and investigate its origin. We study two LINER nuclei; NGC 1052 (type 2) and NGC 4278 (type 1). The data consist on different observations in different epochs (timescale of years), taken from XMM-Newton and Chandra archives, respectively. To search for variability we try to fit all the spectra with the same model using XSPEC; if we can fit all the spectra with the same parameters, it is supposed that the object is non-variable, whereas if we cannot fit them properly, it will be variable. In the last case we need to let one or more parameters to vary in the model, so it may provide clues to understand the nature of this variability. For NGC 1052 we fit a model containing a thermal component plus two power laws. This results in a variability due to changes in the column density and the slope of the power law, both at hard energies. This scenario is consistent with the variability understood as variations in the clouds intersecting the line of sight of the observer (see Rissalitti et al. (2007, 2010)), and is also compatible with the framework of the clumpy torus model (Elitzur 2006). For NGC 4278 the model contains a thermal component plus a single power law. The spectral fitting results in variations of the slope and

  11. Trace element emissions

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.A.; Erickson, T.A.; Steadman, E.N.; Zygarlicke, C.J.; Hauserman, W.B.; Hassett, D.J.

    1994-10-01

    The Energy & Environmental Research Center (EERC) is carrying out an investigation that will provide methods to predict the fate of selected trace elements in integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) systems to aid in the development of methods to control the emission of trace elements determined to be air toxics. The goal of this project is to identify the effects of critical chemical and physical transformations associated with trace element behavior in IGCC and IGFC systems. The trace elements included in this project are arsenic, chromium, cadmium, mercury, nickel, selenium, and lead. The research seeks to identify and fill, experimentally and/or theoretically, data gaps that currently exist on the fate and composition of trace elements. The specific objectives are to (1) review the existing literature to identify the type and quantity of trace elements from coal gasification systems, (2) perform laboratory-scale experimentation and computer modeling to enable prediction of trace element emissions, and (3) identify methods to control trace element emissions.

  12. Analysis of energy-related CO2 emissions and driving factors in five major energy consumption sectors in China.

    Science.gov (United States)

    Cui, Erqian; Ren, Lijun; Sun, Haoyu

    2016-10-01

    Continual growth of energy-related CO2 emissions in China has received great attention, both domestically and internationally. In this paper, we evaluated the CO2 emissions in five major energy consumption sectors which were evaluated from 1991 to 2012. In order to analyze the driving factors of CO2 emission change in different sectors, the Kaya identity was extended by adding several variables based on specific industrial characteristics and a decomposition analysis model was established according to the LMDI method. The results demonstrated that economic factor was the leading force explaining emission increase in each sector while energy intensity and sector contribution were major contributors to emission mitigation. Meanwhile, CO2 emission intensity had no significant influence on CO2 emission in the short term, and energy consumption structure had a small but growing negative impact on the increase of CO2 emissions. In addition, the future CO2 emissions of industry from 2013 to 2020 under three scenarios were estimated, and the reduction potential of CO2 emissions in industry are 335 Mt in 2020 under lower-emission scenario while the CO2 emission difference between higher-emission scenario and lower-emission scenario is nearly 725 Mt. This paper can offer complementary perspectives on determinants of energy-related CO2 emission change in different sectors and help to formulate mitigation strategies for CO2 emissions.

  13. Assessing uncertainties in crop and pasture ensemble model simulations of productivity and N2O emissions

    Science.gov (United States)

    Simulation models are extensively used to predict agricultural productivity and greenhouse gas (GHG) emissions. However, the uncertainties of (reduced) model ensemble simulations have not been assessed systematically for variables affecting food security and climate change mitigation, within multisp...

  14. Carbon emissions from fires in tropical and subtropical ecosystems

    NARCIS (Netherlands)

    Van der Werf, Guido R.; Randerson, James T.; Collatz, G. James; Giglio, Louis

    Global carbon emissions from fires are difficult to quantify and have the potential to influence interannual variability and long-term trends in atmospheric CO2 concentrations. We used 4 years of Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) satellite data and a

  15. Multi-Waveband Emission Maps of Blazars Alan Marscher1 ...

    Indian Academy of Sciences (India)

    their apparent luminosity into high-energy photons. The γ-ray luminosity can be as much as three orders of magnitude higher than that at other wavebands. Furthermore, the emission regions must be very small, since the time-scales of variability can be as short as hours. While relativistic beaming with Doppler factors of ...

  16. Emissions modeling of fluidised bed co-combustion of poultry litter and peat

    OpenAIRE

    Henihan, Anne Marie; Leahy, Martin J.; Leahy, J. J.; Cummins, E; B. P. Kelleher

    2003-01-01

    peer-reviewed Gaseous emissions from the fluidised bed co-combustion of 50% w/w chicken litter and peat were monitored and recorded. Emission data were used to create a dispersion model for a proposed site on a poultry farm in Ireland. Variables within the combustion unit influenced both combustion and emission levels of pollutants such as SO2 and NOx, CO. Concentrations of atmospheric pollutants decreased with use of the correct ratio between fluidising and secondary air. Dispersion model...

  17. THz wave emission microscope

    Science.gov (United States)

    Yuan, Tao

    Sensing and imaging using Terahertz (THz) radiation has attracted more and more interest in the last two decades thanks to the abundant material 'finger prints' in the THz frequency range. The low photon energy also makes THz radiation an attractive tool for nondestructive evaluation of materials and devices, biomedical applications, security checks and explosive screening. Due to the long wavelength, the far-field THz wave optical systems have relatively low spatial resolution. This physical limitation confines THz wave sensing and imaging to mostly macro-size samples. To investigate local material properties or micro-size structures and devices, near-field technology has to be employed. In this dissertation, the Electro-Optical THz wave emission microscope is investigated. The basic principle is to focus the femtosecond laser to a tight spot on a thin THz emitter layer to produce a THz wave source with a similar size as the focus spot. The apparatus provides a method for placing a THz source with sub-wavelength dimension in the near-field range of the investigated sample. Spatial resolution to the order of one tenth of the THz wavelength is demonstrated by this method. The properties of some widely used THz wave emission materials under tight focused pump light are studied. As an important branch of THz time domain spectroscopy (THz-TDS), THz wave emission spectroscopy has been widely used as a tool to investigate the material physics, such as energy band structure, carrier dynamics, material nonlinear properties and dynamics. As the main work of this dissertation, we propose to combine the THz wave emission spectroscopy with scanning probe microscopy (SPM) to build a tip-assisted THz wave emission microscope (TATEM), which is a valuable extension to current SPM science and technology. Illuminated by a femtosecond laser, the biased SPM tip forms a THz wave source inside the sample beneath the tip. The source size is proportional to the apex size of the tip so

  18. Emissions tradeoffs associated with cofiring forest biomass with coal: A case study in Colorado, USA

    Science.gov (United States)

    Dan Loeffler; Nathaniel Anderson

    2014-01-01

    Cofiring forest biomass residues with coal to generate electricity is often cited for its potential to offset fossil fuels and reduce greenhouse gas emissions, but the extent to which cofiring achieves these objectives is highly dependent on case specific variables. This paper uses facility and forest specific data to examine emissions from cofiring forest biomass with...

  19. Monoterpene emissions from a Pacific Northwest Old-Growth Forest and impact on regional biogenic VOC emission estimates

    Science.gov (United States)

    Pressley, Shelley; Lamb, Brian; Westberg, Hal; Guenther, Alex; Chen, Jack; Allwine, Eugene

    Measurements of natural hydrocarbon emission rates are reported for an old-growth Pacific Northwest coniferous forest. The emission data were collected for the two dominant species Douglas-fir ( Pseudotsuga menziesii) and western hemlock ( Tsuga heterophylla) during the growing season in 1997 and 1998 using branch enclosure techniques. Samples were collected at different heights from 13 to 51 m within the canopy using the Wind River Canopy Crane facility. The standard emission factor at a temperature of 30°C and the temperature coefficient for Douglas-fir is Es=0.39±0.14 μg C g -1 h -1 and β=0.14±0.05°C -1 and for western hemlock Es=0.95±0.17 μg C g -1 h -1 and β=0.06±0.02°C -1. There was considerable variability among all the emission factors due to seasonal and branch-to-branch variations. Within season emission factors appear to decline from May to September for the Douglas-fir, although there was no corresponding decrease for the western hemlock. There was no significant difference in standard emission factors ( Es) or temperature coefficients as a function of sunlit versus shady growth environment (different heights) for Douglas-fir, but western hemlock emission samples collected low in the canopy showed no exponential correlation with temperature. Applying the standard emission factors from this study to a Pacific Northwest domain and comparing the modified emission inventory to the current regulatory-based emission inventory yielded a net decrease of 19% in the domain wide monoterpene emissions. The relatively small difference in biogenic emissions is slightly misleading, as the difference in standard emission rates between this study and current regulatory rates is quite significant, and they offset each other when combined in this domain. When this inventory was input into a regional photochemical air quality simulation using the MM5/CMAQ system, the reduction in biogenic emissions resulted in an insignificant decrease of O 3 and a significant

  20. Resiliencia y variables sociodemograficas

    OpenAIRE

    Calero Martinez, Edgar David

    2015-01-01

    En el presente trabajo se aborda la definición de una de las variables dentro de lo que se denomina Capital psicológico positivo, la Resiliencia, sus principales características y algunas de las variables socio demográficas que en el estudio pretenden ver el nivel de relación existente entre cada una de ellas (indirecta o directamente) en el proceso resiliente de una persona para posteriores discusiones y su implicación dentro de la gestión empresarial y sus direcciones futuras.

  1. Validation and Variability

    DEFF Research Database (Denmark)

    Carusi, Annamaria

    2014-01-01

    as inter-subject variability. This need is simultaneously social and epistemic: social as systems biologists attempt to engage with the interests and concerns of clinicians and others in applied medical research; epistemic as they attempt to develop new strategies to cope with variability in the validation...... of the computational models typical of systems biology. This paper describes one attempt to develop such a strategy: a trial with a population of models approach in the context of cardiac electrophysiology. I discuss the development of this approach against the background of ongoing tensions between mathematically...

  2. Applied complex variables

    CERN Document Server

    Dettman, John W

    1965-01-01

    Analytic function theory is a traditional subject going back to Cauchy and Riemann in the 19th century. Once the exclusive province of advanced mathematics students, its applications have proven vital to today's physicists and engineers. In this highly regarded work, Professor John W. Dettman offers a clear, well-organized overview of the subject and various applications - making the often-perplexing study of analytic functions of complex variables more accessible to a wider audience. The first half of Applied Complex Variables, designed for sequential study, is a step-by-step treatment of fun

  3. Internal variables in thermoelasticity

    CERN Document Server

    Berezovski, Arkadi

    2017-01-01

    This book describes an effective method for modeling advanced materials like polymers, composite materials and biomaterials, which are, as a rule, inhomogeneous. The thermoelastic theory with internal variables presented here provides a general framework for predicting a material’s reaction to external loading. The basic physical principles provide the primary theoretical information, including the evolution equations of the internal variables. The cornerstones of this framework are the material representation of continuum mechanics, a weak nonlocality, a non-zero extra entropy flux, and a consecutive employment of the dissipation inequality. Examples of thermoelastic phenomena are provided, accompanied by detailed procedures demonstrating how to simulate them.

  4. Terrestrial Carbon Cycle Variability.

    Science.gov (United States)

    Baldocchi, Dennis; Ryu, Youngryel; Keenan, Trevor

    2016-01-01

    A growing literature is reporting on how the terrestrial carbon cycle is experiencing year-to-year variability because of climate anomalies and trends caused by global change. As CO 2 concentration records in the atmosphere exceed 50 years and as satellite records reach over 30 years in length, we are becoming better able to address carbon cycle variability and trends. Here we review how variable the carbon cycle is, how large the trends in its gross and net fluxes are, and how well the signal can be separated from noise. We explore mechanisms that explain year-to-year variability and trends by deconstructing the global carbon budget. The CO 2 concentration record is detecting a significant increase in the seasonal amplitude between 1958 and now. Inferential methods provide a variety of explanations for this result, but a conclusive attribution remains elusive. Scientists have reported that this trend is a consequence of the greening of the biosphere, stronger northern latitude photosynthesis, more photosynthesis by semi-arid ecosystems, agriculture and the green revolution, tropical temperature anomalies, or increased winter respiration. At the global scale, variability in the terrestrial carbon cycle can be due to changes in constituent fluxes, gross primary productivity, plant respiration and heterotrophic (microbial) respiration, and losses due to fire, land use change, soil erosion, or harvesting. It remains controversial whether or not there is a significant trend in global primary productivity (due to rising CO 2 , temperature, nitrogen deposition, changing land use, and preponderance of wet and dry regions). The degree to which year-to-year variability in temperature and precipitation anomalies affect global primary productivity also remains uncertain. For perspective, interannual variability in global gross primary productivity is relatively small (on the order of 2 Pg-C y -1 ) with respect to a large and uncertain background (123 +/- 4 Pg-C y -1 ), and

  5. Complex variables I essentials

    CERN Document Server

    Solomon, Alan D

    2013-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Complex Variables I includes functions of a complex variable, elementary complex functions, integrals of complex functions in the complex plane, sequences and series, and poles and r

  6. Anomalous CO2 Emissions in Different Ecosystems Around the World

    Science.gov (United States)

    Sanchez-Canete, E. P.; Moya Jiménez, M. R.; Kowalski, A. S.; Serrano-Ortiz, P.; López-Ballesteros, A.; Oyonarte, C.; Domingo, F.

    2016-12-01

    As an important tool for understanding and monitoring ecosystem dynamics at ecosystem level, the eddy covariance (EC) technique allows the assessment of the diurnal and seasonal variation of the net ecosystem exchange (NEE). Despite the high temporal resolution data available, there are still many processes (in addition to photosynthesis and respiration) that, although they are being monitored, have been neglected. Only a few authors have studied anomalous CO2 emissions (non biological), and have related them to soil ventilation, photodegradation or geochemical processes. The aim of this study is: 1) to identify anomalous short term CO2 emissions in different ecosystems distributed around the world, 2) to determine the meteorological variables that are influencing these emissions, and 3) to explore the potential processes that can be involved. We have studied EC data together with other meteorological ancillary variables obtained from the FLUXNET database (version 2015) and have found more than 50 sites with anomalous CO2 emissions in different ecosystem types such as grasslands, croplands or savannas. Data were filtered according to the FLUXNET quality control flags (only data with quality control flag equal to 0 was used) and correlation analysis were performed with NEE and ancillary data. Preliminary results showed strong and highly significant correlations between meteorological variables and anomalous CO2 emissions. Correlation results showed clear differing behaviors between ecosystems types, which could be related to the different processes involved in the anomalous CO2 emissions. We suggest that anomalous CO2 emissions are happening globally and therefore, their contribution to the global net ecosystem carbon balance requires further investigation in order to better understand its drivers.

  7. Can dust emission mechanisms be determined from field measurements?

    Science.gov (United States)

    Klose, Martina; Webb, Nicholas; Gill, Thomas E.; Van Pelt, Scott; Okin, Gregory

    2017-04-01

    Field observations are needed to develop and test theories on dust emission for use in dust modeling systems. The dust emission mechanism (aerodynamic entrainment, saltation bombardment, aggregate disintegration) as well as the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This variability, which is caused by heterogeneity of the surface and the atmosphere, cannot be fully captured in either field measurements or models. However, uncertainty in dust emission modeling can be reduced through more detailed observational data on the dust emission mechanism itself. To date, most measurements do not provide enough information to allow for a determination of the mechanisms leading to dust emission and often focus on a small variety of soil and atmospheric settings. Additionally, data sets are often not directly comparable due to different measurement setups. As a consequence, the calibration of dust emission schemes has so far relied on a selective set of observations, which leads to an idealization of the emission process in models and thus affects dust budget estimates. Here, we will present results of a study which aims to decipher the dust emission mechanism from field measurements as an input for future model development. Detailed field measurements are conducted, which allow for a comparison of dust emission for different surface and atmospheric conditions. Measurements include monitoring of the surface, loose erodible material, transported sediment, and meteorological data, and are conducted in different environmental settings in the southwestern United States. Based on the field measurements, a method is developed to differentiate between the different dust emission mechanisms.

  8. Improving ammonia emissions in air quality modelling for France

    Science.gov (United States)

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

    2014-08-01

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

  9. Biological Sampling Variability Study

    Energy Technology Data Exchange (ETDEWEB)

    Amidan, Brett G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-11-08

    There are many sources of variability that exist in the sample collection and analysis process. This paper addresses many, but not all, sources of variability. The main focus of this paper was to better understand and estimate variability due to differences between samplers. Variability between days was also studied, as well as random variability within each sampler. Experiments were performed using multiple surface materials (ceramic and stainless steel), multiple contaminant concentrations (10 spores and 100 spores), and with and without the presence of interfering material. All testing was done with sponge sticks using 10-inch by 10-inch coupons. Bacillus atrophaeus was used as the BA surrogate. Spores were deposited using wet deposition. Grime was coated on the coupons which were planned to include the interfering material (Section 3.3). Samples were prepared and analyzed at PNNL using CDC protocol (Section 3.4) and then cultured and counted. Five samplers were trained so that samples were taken using the same protocol. Each sampler randomly sampled eight coupons each day, four coupons with 10 spores deposited and four coupons with 100 spores deposited. Each day consisted of one material being tested. The clean samples (no interfering materials) were run first, followed by the dirty samples (coated with interfering material). There was a significant difference in recovery efficiency between the coupons with 10 spores deposited (mean of 48.9%) and those with 100 spores deposited (mean of 59.8%). There was no general significant difference between the clean and dirty (containing interfering material) coupons or between the two surface materials; however, there was a significant interaction between concentration amount and presence of interfering material. The recovery efficiency was close to the same for coupons with 10 spores deposited, but for the coupons with 100 spores deposited, the recovery efficiency for the dirty samples was significantly larger (65

  10. Proper elimination of latent variables

    NARCIS (Netherlands)

    Polderman, Jan W.

    1997-01-01

    We consider behaviors in which we distinguish two types of variables, manifest variables, the variables that are of interest to the user and latent variables, the variables that are introduced to obtain a first representation. The problem is to find a representation of the manifest behavior, that

  11. Simulating Radio Emission from Low-mass Stars

    Science.gov (United States)

    Llama, Joe; Jardine, Moira M.; Wood, Kenneth; Hallinan, Gregg; Morin, Julien

    2018-02-01

    Understanding the origins of stellar radio emission can provide invaluable insight into the strength and geometry of stellar magnetic fields and the resultant space weather environment experienced by exoplanets. Here, we present the first model capable of predicting radio emission through the electron cyclotron maser instability using observed stellar magnetic maps of low-mass stars. We determine the structure of the coronal magnetic field and plasma using spectropolarimetric observations of the surface magnetic fields and the X-ray emission measure. We then model the emission of photons from the locations within the corona that satisfy the conditions for electron cyclotron maser emission. Our model predicts the frequency and intensity of radio photons from within the stellar corona. We have benchmarked our model against the low-mass star V374 Peg. This star has both radio observations from the Very Large Array and a nearly simultaneous magnetic map. Using our model we are able to fit the radio observations of V374 Peg, providing additional evidence that the radio emission observed from low-mass stars may originate from the electron cyclotron maser instability. Our model can now be extended to all stars with observed magnetic maps to predict the expected frequency and variability of stellar radio emission in an effort to understand and guide future radio observations of low-mass stars.

  12. Spatial Variability of Rainfall

    DEFF Research Database (Denmark)

    Jensen, N.E.; Pedersen, Lisbeth

    2005-01-01

    As a part of a Local Area Weather Radar (LAWR) calibration exercise 15 km south of Århus, Denmark, the variability in accumulated rainfall within a single radar pixel (500 by 500 m) was measured using nine high-resolution rain gauges. The measured values indicate up to a 100% variation between ne...

  13. Variability in GPS sources

    NARCIS (Netherlands)

    Jauncey, DL; King, EA; Bignall, HE; Lovell, JEJ; Kedziora-Chudczer, L; Tzioumis, AK; Tingay, SJ; Macquart, JP; McCulloch, PM

    2003-01-01

    Flux density monitoring data at 2.3 and 8.4 GHz is presented for a sample of 33 southern hemisphere GPS sources, drawn from the 2.7 GHz Parkes survey. This monitoring data, together with VLBI monitoring data, shows that a small fraction of these sources, similar to10%, vary. Their variability falls

  14. Classes of Instructional Variables.

    Science.gov (United States)

    Reigeluth, Charles M.; Merrill, M. David

    1979-01-01

    Describes three classes of variables which should be considered when one is designing instructional materials, doing research on instruction, or developing better methods of instruction, and proposes a classification scheme which is summarized in the last of the 13 figures that illustrate the article. A blbliography is included. (Author/RAO)

  15. Variable rate irrigation

    Science.gov (United States)

    Systems are available to producers to make variable-rate applications of defoliants, fertilizer, lime, pesticides, plant growth regulators, and seed. These systems could potentially offer cost savings to a producer; however, the full potential of the benefits and savings cannot be realized if water ...

  16. Variable gravity research facility

    Science.gov (United States)

    Allan, Sean; Ancheta, Stan; Beine, Donna; Cink, Brian; Eagon, Mark; Eckstein, Brett; Luhman, Dan; Mccowan, Daniel; Nations, James; Nordtvedt, Todd

    1988-01-01

    Spin and despin requirements; sequence of activities required to assemble the Variable Gravity Research Facility (VGRF); power systems technology; life support; thermal control systems; emergencies; communication systems; space station applications; experimental activities; computer modeling and simulation of tether vibration; cost analysis; configuration of the crew compartments; and tether lengths and rotation speeds are discussed.

  17. Typhoon Structural Variability,

    Science.gov (United States)

    1985-10-01

    1980: An analytical model of the wind and pressure profiles in hurricanes. Mort . KUa. Rev., 108, 8, 1212-1218. Holland, G. J., and R. T. Merrill, 1984...Recipient’s Acce..sion No. SHEET ATS-391 4. Title and Subit le 5. Report Date Typhoon Structural Variability October, 1985 6. 7. Author(s) S. Performing

  18. Variable thrust cartridge

    Science.gov (United States)

    Taleyarkhan, Rusi P.

    2000-11-07

    The present invention is a variable thrust cartridge comprising a water-molten aluminum reaction chamber from which a slug is propelled. The cartridge comprises a firing system that initiates a controlled explosion from the reaction chamber. The explosive force provides a thrust to a slug, preferably contained within the cartridge.

  19. Variability and component composition

    NARCIS (Netherlands)

    T. van der Storm (Tijs)

    2004-01-01

    textabstractIn component-based product populations, feature models have to be described at the component level to be able to benefit from a product family approach. As a consequence, composition of components becomes very complex. We describe how component-level variability can be managed in the

  20. Variable speed generators

    CERN Document Server

    Boldea, Ion

    2005-01-01

    With the deregulation of electrical energy production and distribution, says Boldea (Polytechnical Institute, Timisoara, Romania) producers are looking for ways to tailor their electricity for different markets. Variable-speed electric generators are serving that purpose, up to the 400 megavolt ampere unit size, in Japan since 1996 and Germany sinc

  1. All Those Independent Variables.

    Science.gov (United States)

    Meacham, Merle L.

    This paper presents a case study of a sixth grade remedial math class which illustrates the thesis that only the "experimental attitude," not the "experimental method," is appropriate in the classroom. The thesis is based on the fact that too many independent variables exist in a classroom situation to allow precise measurement. The case study…

  2. Time-resolved analysis of particle emissions from residential biomass combustion - Emissions of refractory black carbon, PAHs and organic tracers

    Science.gov (United States)

    Nielsen, Ingeborg E.; Eriksson, Axel C.; Lindgren, Robert; Martinsson, Johan; Nyström, Robin; Nordin, Erik Z.; Sadiktsis, Ioannis; Boman, Christoffer; Nøjgaard, Jacob K.; Pagels, Joakim

    2017-09-01

    Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of

  3. NOx emission trends over Chinese cities estimated from OMI observations during 2005 to 2015

    Science.gov (United States)

    Liu, Fei; Beirle, Steffen; Zhang, Qiang; van der A, Ronald J.; Zheng, Bo; Tong, Dan; He, Kebin

    2017-08-01

    Satellite nitrogen dioxide (NO2) observations have been widely used to evaluate emission changes. To determine trends in nitrogen oxides (NOx) emission over China, we used a method independent of chemical transport models to quantify the NOx emissions from 48 cities and seven power plants over China, on the basis of Ozone Monitoring Instrument (OMI) NO2 observations from 2005 to 2015. We found that NOx emissions over 48 Chinese cities increased by 52 % from 2005 to 2011 and decreased by 21 % from 2011 to 2015. The decrease since 2011 could be mainly attributed to emission control measures in power sector; while cities with different dominant emission sources (i.e., power, industrial, and transportation sectors) showed variable emission decline timelines that corresponded to the schedules for emission control in different sectors. The time series of the derived NOx emissions was consistent with the bottom-up emission inventories for all power plants (r = 0. 8 on average), but not for some cities (r = 0. 4 on average). The lack of consistency observed for cities was most probably due to the high uncertainty of bottom-up urban emissions used in this study, which were derived from downscaling the regional-based emission data to city level by using spatial distribution proxies.

  4. NOx emission trends over Chinese cities estimated from OMI observations during 2005 to 2015

    Directory of Open Access Journals (Sweden)

    F. Liu

    2017-08-01

    Full Text Available Satellite nitrogen dioxide (NO2 observations have been widely used to evaluate emission changes. To determine trends in nitrogen oxides (NOx emission over China, we used a method independent of chemical transport models to quantify the NOx emissions from 48 cities and seven power plants over China, on the basis of Ozone Monitoring Instrument (OMI NO2 observations from 2005 to 2015. We found that NOx emissions over 48 Chinese cities increased by 52 % from 2005 to 2011 and decreased by 21 % from 2011 to 2015. The decrease since 2011 could be mainly attributed to emission control measures in power sector; while cities with different dominant emission sources (i.e., power, industrial, and transportation sectors showed variable emission decline timelines that corresponded to the schedules for emission control in different sectors. The time series of the derived NOx emissions was consistent with the bottom-up emission inventories for all power plants (r = 0. 8 on average, but not for some cities (r = 0. 4 on average. The lack of consistency observed for cities was most probably due to the high uncertainty of bottom-up urban emissions used in this study, which were derived from downscaling the regional-based emission data to city level by using spatial distribution proxies.

  5. Characterization of wildfire NOx emissions using MODIS fire radiative power and OMI tropospheric NO2 columns

    Directory of Open Access Journals (Sweden)

    R. C. Cohen

    2011-06-01

    Full Text Available We use observations of fire radiative power (FRP from the Moderate Resolution Imaging Spectroradiometer~(MODIS and tropospheric NO2 column measurements from the Ozone Monitoring Instrument (OMI to derive NO2 wildfire emission coefficients (g MJ−1 for three land types over California and Nevada. Retrieved emission coefficients were 0.279±0.077, 0.342±0.053, and 0.696±0.088 g MJ−1 NO2 for forest, grass and shrub fuels, respectively. These emission coefficients reproduce ratios of emissions with fuel type reported previously using independent methods. However, the magnitude of these coefficients is lower than prior estimates. While it is possible that a negative bias in the OMI NO2 retrieval over regions of active fire emissions is partly responsible, comparison with several other studies of fire emissions using satellite platforms indicates that current emission factors may overestimate the contributions of flaming combustion and underestimate the contributions of smoldering combustion to total fire emissions. Our results indicate that satellite data can provide an extensive characterization of the variability in fire NOx emissions; 67 % of the variability in emissions in this region can be accounted for using an FRP-based parameterization.

  6. Aircraft Engine Emissions Estimator

    Science.gov (United States)

    1985-11-01

    Protection Agency, " Control of Air Pollution From Aircraft and Aircraft Engines," 43 FR 12615, March 24, Vq7. 51 ~~SL% 12. Souza, A.F. F-100 Afterburner...R.G. Technical Support Report-Aircraft Emissions Factors, USEPA Office of Mobile Source Air Pollution Control , Ann Arbor, MI, March 1977. 14. Souza, A.F...STAVILITY CATEGOUY 6 WIND SPELU (METERS/SECOND) 1600 WINU DIRECTION TAILWIN) TEMPERATURa " (F) 38.0O MIXING DEPT" (METLRS) l1.o00

  7. Positron emission tomography

    CERN Document Server

    Paans, A M J

    2006-01-01

    Positron Emission Tomography (PET) is a method for measuring biochemical and physiological processes in vivo in a quantitative way by using radiopharmaceuticals labelled with positron emitting radionuclides such as 11C, 13N, 15O and 18F and by measuring the annihilation radiation using a coincidence technique. This includes also the measurement of the pharmacokinetics of labelled drugs and the measurement of the effects of drugs on metabolism. Also deviations of normal metabolism can be measured and insight into biological processes responsible for diseases can be obtained. At present the combined PET/CT scanner is the most frequently used scanner for whole-body scanning in the field of oncology.

  8. Pulsar magnetoshphere and emission

    Science.gov (United States)

    Qiao, G.; Lee, K.; Zhang, B.; Wang, H.; Xu, R.

    The structure of pulsar magnetospheres depends on the binding energy of matter on the stars - surfaces as well as the distribution of the particles in the magnetospheres For example in the high binding energy case inner gaps core annular or the both can be formed But in the low binding energy case no such gap could work any more Here all possible situations are considered The emission mechanisms for both in radio and gamma -ray are discussed under different magnetospheric structures It is addressed that one could distinguish normal neutron or bare quark stars by their different radiative features in multi-wave bands

  9. Positron Emission Tomography (PET)

    Energy Technology Data Exchange (ETDEWEB)

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  10. Terpenoid and carbonyl emissions from Norway spruce in Finland during the growing season

    Science.gov (United States)

    Hakola, Hannele; Tarvainen, Virpi; Praplan, Arnaud P.; Jaars, Kerneels; Hemmilä, Marja; Kulmala, Markku; Bäck, Jaana; Hellén, Heidi

    2017-03-01

    We present spring and summer volatile organic compound (VOC) emission rate measurements from Norway spruce (Picea abies L. Karst) growing in a boreal forest in southern Finland. The measurements were conducted using in situ gas chromatograph with 1 to 2 h time resolution to reveal quantitative and qualitative short-term and seasonal variability of the emissions. The measurements cover altogether 14 weeks in years 2011, 2014 and 2015. Monoterpene (MT) and sesquiterpene (SQT) emission rates were measured all the time, but isoprene only in 2014 and 2015 and acetone and C4-C10 aldehydes only in 2015. The emission rates of all the compounds were low in spring, but MT, acetone, and C4-C10 aldehyde emission rates increased as summer proceeded, reaching maximum emission rates in July. Late summer mean values (late July and August) were 29, 17, and 33 ng g(dw)-1 h-1 for MTs, acetone, and aldehydes respectively. SQT emission rates increased during the summer and highest emissions were measured in late summer (late summer mean value 84 ng g(dw)-1 h-1) concomitant with highest linalool emissions most likely due to stress effects. The between-tree variability of emission pattern was studied by measuring seven different trees during the same afternoon using adsorbent tubes. Especially the contributions of limonene, terpinolene, and camphene were found to vary between trees, whereas proportions of α-pinene (25 ± 5 %) and β-pinene (7 ± 3 %) were more stable. Our results show that it is important to measure emissions at canopy level due to irregular emission pattern, but reliable SQT emission data can be measured only from enclosures. SQT emissions contributed more than 90 % of the ozone reactivity most of the time, and about 70 % of the OH reactivity during late summer. The contribution of aldehydes to OH reactivity was comparable to that of MT during late summer, 10-30 % most of the time.

  11. Switchable sensitizers stepwise lighting up lanthanide emissions

    Science.gov (United States)

    Zhang, Yan; Jiao, Peng-Chong; Xu, Hai-Bing; Tang, Ming-Jing; Yang, Xiao-Ping; Huang, Shaoming; Deng, Jian-Guo

    2015-01-01

    Analagous to a long-ranged rocket equipped with multi-stage engines, a luminescent compound with consistent emission signals across a large range of concentrations from two stages of sensitizers can be designed. In this approach, ACQ, aggregation-caused quenching effect of sensitizers, would stimulate lanthanide emission below 10−4 M, and then at concentrations higher than 10−3 M, the “aggregation-induced emission” (AIE) effect of luminophores would be activated with the next set of sensitizers for lanthanide emission. Simultaneously, the concentration of the molecules could be monitored digitally by the maximal excitation wavelengths, due to the good linear relationship between the maximal excitation wavelengths and the concentrations {lg(M)}. This model, wherein molecules are assembled with two stages (both AIE and ACQ effect) of sensitizers, may provide a practicable strategy for design and construction of smart lanthanide bioprobes, which are suitable in complicated bioassay systems in which concentration is variable. PMID:25791467

  12. Estimating carbon emissions from African wildfires

    Directory of Open Access Journals (Sweden)

    V. Lehsten

    2009-03-01

    Full Text Available We developed a technique for studying seasonal and interannual variation in pyrogenic carbon emissions from Africa using a modelling approach that scales burned area estimates from L3JRC, a map recently generated from remote sensing of burn scars instead of active fires. Carbon fluxes were calculated by the novel fire model SPITFIRE embedded within the dynamic vegetation model framework LPJ-GUESS, using daily climate input.

    For the time period from 2001 to 2005 an average area of 195.5±24×104 km2 was burned annually, releasing an average of 723±70 Tg C to the atmosphere; these estimates for the biomass burned are within the range of previously published estimates. Despite the fact that the majority of wildfires are ignited by humans, strong relationships between climatic conditions (particularly precipitation, net primary productivity and overall biomass burnt emerged. Our investigation of the relationships between burnt area and carbon emissions and their potential drivers available litter and precipitation revealed uni-modal responses to annual precipitation, with a maximum around 1000 mm for burned area and emissions, or 1200 mm for litter availability. Similar response patterns identified in savannahs worldwide point to precipitation as a chief determinant for short-term variation in fire regime. A considerable variability that cannot be explained by fire-precipitation relationships alone indicates the existence of additional factors that must be taken into account.

  13. Black carbon emissions in China

    Science.gov (United States)

    Streets, David G.; Gupta, Shalini; Waldhoff, Stephanie T.; Wang, Michael Q.; Bond, Tami C.; Yiyun, Bo

    Black carbon (BC) is an important aerosol species because of its global and regional influence on radiative forcing and its local effects on the environment and human health. We have estimated the emissions of BC in China, where roughly one-fourth of global anthropogenic emissions is believed to originate. China's high rates of usage of coal and biofuels are primarily responsible for high BC emissions. This paper pays particular attention to the application of appropriate emission factors for China and the attenuation of these emissions where control devices are used. Nevertheless, because of the high degree of uncertainty associated with BC emission factors, we provide ranges of uncertainty for our emission estimates, which are approximately a factor of eight. In our central case, we calculate that BC emissions in China in 1995 were 1342 Gg, about 83% being generated by the residential combustion of coal and biofuels. We estimate that BC emissions could fall to 1224 Gg by 2020. This 9% decrease in BC emissions can be contrasted with the expected increase of 50% in energy use; the reduction will be obtained because of a transition to more advanced technology, including greater use of coal briquettes in place of raw coal in cities and towns. The increased use of diesel vehicles in the future will result in a greater share of the transport sector in total BC emissions. Spatially, BC emissions are predominantly distributed in an east-west swath across China's heartland, where the rural use of coal and biofuels for cooking and heating is widespread. This is in contrast to the emissions of most other anthropogenically derived air pollutants, which are closely tied to population and industrial centers.

  14. Probing Terrestrial Planet Formation with Extreme Disk Variability

    Science.gov (United States)

    Su, Kate; Rieke, George; Gaspar, Andras; Jackson, Alan

    2016-08-01

    Spitzer has advanced our knowledge about the critical stages of terrestrial planet formation (and in some cases destruction) by discovering young stars orbited by 1.) silica dust emission close to their terrestrial zones indicative of the violent collisions, and 2.) variable disk emission arising from the aftermath of asteroid-size impacts. The variable emission provides a unique opportunity to learn about asteroid-sized bodies in young exoplanetary systems and to explore planetesimal collisions and their aftermaths during the era of terrestrial-planet-building. We propose continued study of debris disk variability, focused in two areas: (1) to provide continuous monitoring of systems where our existing program has discovered substantial variations indicative of major ongoing episodes of planetesimal impacts; and (2) to investigate intensively possible variations in the dust content of systems that show prominent crystalline emission features to establish a link between the two indicators of planet building. Together these objectives will prepare us for the JWST era, when we will again obtain mid-infrared spectra of these systems, and of both higher spectral resolution and signal to noise than has been possible previously. This program will extend the time-domain study of extreme debris disks as an important heritage of the Spitzer warm mission.

  15. Elastic emission polishing

    Energy Technology Data Exchange (ETDEWEB)

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  16. Zero emission coal

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, H.; Lackner, K.

    2000-08-01

    We discuss a novel, emission-free process for producing hydrogen or electricity from coal. Even though we focus on coal, the basic design is compatible with any carbonaceous fuel. The process uses cyclical carbonation of calcium oxide to promote the production of hydrogen from carbon and water. The carbonation of the calcium oxide removes carbon dioxide from the reaction products and provides the additional energy necessary to complete hydrogen production without additional combustion of carbon. The calcination of the resulting calcium carbonate is accomplished using the high temperature waste heat from solid oxide fuel cells (SOFC), which generate electricity from hydrogen fuel. Converting waste heat back to useful chemical energy allows the process to achieve very high conversion efficiency from fuel energy to electrical energy. As the process is essentially closed-loop, the process is able to achieve zero emissions if the concentrated exhaust stream of CO{sub 2} is sequestered. Carbon dioxide disposal is accomplished by the production of magnesium carbonate from ultramafic rock. The end products of the sequestration process are stable naturally occurring minerals. Sufficient rich ultramafic deposits exist to easily handle all the world's coal.

  17. Emission inventory for fugitive emissions from fuel in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2013. The inventory of fugitive emissions includes CO2, CH4, N2O, SO2, NOx, NMVOC, CO, particulate matter, Black carbon, heavy metals, dioxin and PAHs. In 2013 the total...... of fugitive CH4 emission is production of oil and gas in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from oil and gas production, loading of ships, transmission and distribution of oil, and to a less...

  18. Technological Capability's Predictor Variables

    Directory of Open Access Journals (Sweden)

    Fernanda Maciel Reichert

    2011-03-01

    Full Text Available The aim of this study was to identify the factors that influence in configuration of the technological capability of companies in sectors with medium-low technological intensity. To achieve the goal proposed in this article a survey was carried out. Based on the framework developed by Lall (1992 which classifies firms in basic, intermediate and advanced level of technological capability; it was found that the predominant technological capability is intermediate, with 83.7% of respondent companies (plastics companies in Brazil. It is believed that the main contribution of this study is the finding that the dependent variable named “Technological Capability” can be explained at a rate of 65% by six variables: development of new processes; selection of the best equipment supplier; sales of internally developed new technology to third parties; design and manufacture of equipment; study of the work methods and perform inventory control; and improvement of product quality.

  19. Complex variable HVPT

    Energy Technology Data Exchange (ETDEWEB)

    Killingbeck, John P [Mathematics Department, University of Hull, Hull HU6 7RX (United Kingdom); Grosjean, Alain [Laboratoire d' Astrophysique de l' Observatoire de Besancon (CNRS, UPRES-A 6091), 41 bis Avenue de l' Observatoire, BP 1615, 25010 Besancon Cedex (France); Jolicard, Georges [Laboratoire d' Astrophysique de l' Observatoire de Besancon (CNRS, UPRES-A 6091), 41 bis Avenue de l' Observatoire, BP 1615, 25010 Besancon Cedex (France)

    2004-08-13

    Complex variable hypervirial perturbation theory is applied to the case of oscillator and Coulomb potentials perturbed by a single term potential of the form Vx{sup n} or Vr{sup n}, respectively. The trial calculations reported show that this approach can produce accurate complex energies for resonant states via a simple and speedy calculation and can also be useful in studies of PT symmetry and tunnelling resonance effects. (addendum)

  20. Spreading with variable viscosity

    OpenAIRE

    Foit, J.J.

    1997-01-01

    Ausbreitung mit variabler Viskosität Die isotherme Ausbreitung eines Volumenstromes, , in Form von dünnen Schichten kann mit Hilfe selbstähnlicher Lösungen beschrieben werden (Huppert). Für die axialsymmetrische Ausbreitung eines konstanten Volumens mit einer variablen Viskosität von der Form existieren ebenfalls selbstähnliche Lösungen (Sakimoto, Zuber). Dieses Ergebnis wird auf den Fall einer eindimensionalen und einer axialsymmetrischen Ausbreitung für alle , erweitert.

  1. Historical Variable Star Catalogs

    OpenAIRE

    Pagnotta, Ashley; Graur, Or; Murray, Zachary; Kruk, Julia; Christie-Dervaux, Lucien; Chen, Dong Yi

    2015-01-01

    Slides from my talk during one of the Historical Astronomy Division sessions at AAS 225 in Seattle, WA (January 2015). A brief history of the variable star catalogs Henrietta Swan Leavitt and Cecilia Payne-Gaposchkin assembled at Harvard, and the update to them that some of our students at AMNH have done.(Figshare only previews the first few slides. Download the PDF to see all of them!)

  2. Score test variable screening

    OpenAIRE

    Zhao, Sihai Dave; Li, Yi

    2014-01-01

    Variable screening has emerged as a crucial first step in the analysis of high-throughput data, but existing procedures can be computationally cumbersome, difficult to justify theoretically, or inapplicable to certain types of analyses. Motivated by a high-dimensional censored quantile regression problem in multiple myeloma genomics, this paper makes three contributions. First, we establish a score test-based screening framework, which is widely applicable, extremely computationally efficient...

  3. Short Timescale Variability In The Faint Sky Variability Survey

    NARCIS (Netherlands)

    Morales-Rueda, L.; Groot, P.J.; Augusteijn, T.; Nelemans, G.A.; Vreeswijk, P.M.; Besselaar, E.J.M. van den

    2006-01-01

    We present the V band variability analysis of the point sources in the Faint Sky Variability Survey on time scales from 24 minutes to tens of days. We find that about one percent of the point sources down to V = 24 are variables. We discuss the variability detection probabilities for each field

  4. Short timescale variability in the faint sky variability survey

    NARCIS (Netherlands)

    Morales-Rueda, L.; Groot, P.J.; Augusteijn, T.; Nelemans, G.A.; Vreeswijk, P.M.; Besselaar, E.J.M. van den

    2006-01-01

    We present the V-band variability analysis of the Faint Sky Variability Survey (FSVS). The FSVS combines colour and time variability information, from timescales of 24 minutes to tens of days, down to V = 24. We find that �1% of all point sources are variable along the main sequence reaching �3.5%

  5. Population effects and variability.

    Science.gov (United States)

    Dorne, Jean Lou; Amzal, Billy; Bois, Frédéric; Crépet, Amélie; Tressou, Jessica; Verger, Philippe

    2012-01-01

    Chemical risk assessment for human health requires a multidisciplinary approach through four steps: hazard identification and characterization, exposure assessment, and risk characterization. Hazard identification and characterization aim to identify the metabolism and elimination of the chemical (toxicokinetics) and the toxicological dose-response (toxicodynamics) and to derive a health-based guidance value for safe levels of exposure. Exposure assessment estimates human exposure as the product of the amount of the chemical in the matrix consumed and the consumption itself. Finally, risk characterization evaluates the risk of the exposure to human health by comparing the latter to with the health-based guidance value. Recently, many research efforts in computational toxicology have been put together to characterize population variability and uncertainty in each of the steps of risk assessment to move towards more quantitative and transparent risk assessment. This chapter focuses specifically on modeling population variability and effects for each step of risk assessment in order to provide an overview of the statistical and computational tools available to toxicologists and risk assessors. Three examples are given to illustrate the applicability of those tools: derivation of pathway-related uncertainty factors based on population variability, exposure to dioxins, dose-response modeling of cadmium.

  6. Diurnality of soil nitrous oxide (N2O) emissions

    Science.gov (United States)

    Gelfand, I.; Moyer, R.; Poe, A.; Pan, D.; Abraha, M.; Chen, J.; Zondlo, M. A.; Robertson, P.

    2015-12-01

    Soil emissions of nitrous oxide (N2O) are important contributors to the greenhouse gas balance of the atmosphere. Agricultural soils contribute ~65% of anthropogenic N2O emissions. Understanding temporal and spatial variability of N2O emissions from agricultural soils is vital for closure of the global N2O budget and the development of mitigation opportunities. Recent studies have observed higher N2O fluxes during the day and lower at night. Understanding the mechanisms of such diurnality may have important consequences for our understanding of the N cycle. We tested the hypothesis that diurnal cycles are driven by root carbon exudes that stimulate denitrification and therefore N2O production. Alternatively, we considered that the cycle could result from higher afternoon temperatures that accelerate soil microbial activity. We removed all plants from a corn field plot and left another plot untouched. We measured soil N2O emissions in each plot using a standard static chamber technique throughout the corn growing season. And also compared static chamber results to ecosystem level N2O emissions as measured by eddy covariance tower equipped with an open-path N2O sensor. We also measured soil and air temperatures and soil water and inorganic N contents. Soil N2O emissions followed soil inorganic N concentrations and in control plot chambers ranged from 10 μg N m-2 hr-1 before fertilization to 13×103 after fertilization. We found strong diurnal cycles measured by both techniques with emissions low during night and morning hours and high during the afternoon. Corn removal had no effect on diurnality, but had a strong effect on the magnitude of soil N2O emissions. Soil temperature exhibited a weak correlation with soil N2O emissions and could not explain diurnal patterns. Further studies are underway to explore additional mechanisms that might contribute to this potentially important phenomena.

  7. Emissions of particulate matter from animal houses in the Netherlands

    Science.gov (United States)

    Winkel, Albert; Mosquera, Julio; Groot Koerkamp, Peter W. G.; Ogink, Nico W. M.; Aarnink, André J. A.

    2015-06-01

    In the Netherlands, emissions from animal houses represent a major source of ambient particulate matter (PM). The objective of the present paper was to provide accurate and up to date concentrations and emission rates of PM10 and PM2.5 for commonly used animal housing systems, under representative inside and outside climate conditions and ventilation rates. We set up a national survey which covered 13 housing systems for poultry, pigs, and dairy cattle, and included 36 farms. In total, 202 24-h measurements were carried out, which included concentrations of inhalable PM, PM10, PM2.5, and CO2, ventilation rate, temperature, and relative humidity. On an animal basis, geometric mean emission rates of PM10 ranged from 2.2 to 12.0 mg h-1 in poultry and from 7.3 to 22.5 mg h-1 in pigs. The mean PM10 emission rate in dairy cattle was 8.5 mg h-1. Geometric mean emission rates of PM2.5 ranged from 0.11 to 2.41 mg h-1 in poultry and from 0.21 to 1.56 mg h-1 in pigs. The mean PM2.5 emission rate in dairy cattle was 1.65 mg h-1. Emissions are also reported per Livestock Unit and Heat Production Unit. PM emission rates increased exponentially with increasing age in broilers and turkeys and increased linearly with increasing age in weaners and fatteners. In laying hens, broiler breeders, sows, and dairy cattle, emission levels were variable throughout the year.

  8. Nitrous oxide emission budgets and land-use-driven hotspots for organic soils in Europe

    DEFF Research Database (Denmark)

    Leppelt, T; Dechow, R; Gebbert, S

    2014-01-01

    relating the upscaling process to a priori-identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic......Organic soils are a main source of direct emissions of nitrous oxide (N2O), an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time, which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when...

  9. OPIC Greenhouse Gas Emissions Inventory

    Data.gov (United States)

    Overseas Private Investment Corporation — Independent analysis details quantifying the greenhouse gas ("GHG") emissions directly attributable to projects to which the Overseas Private Investment Corporation...

  10. Emissions from photovoltaic life cycles.

    Science.gov (United States)

    Fthenakis, Vasilis M; Kim, Hyung Chul; Alsema, Erik

    2008-03-15

    Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004-2006, this study presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions from four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system. Among the current vintage of PV technologies, thin-film cadmium telluride (CdTe) PV emits the least amount of harmful air emissions as it requires the least amount of energy during the module production. However, the differences in the emissions between different PV technologies are very small in comparison to the emissions from conventional energy technologies that PV could displace. As a part of prospective analysis, the effect of PV breeder was investigated. Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.

  11. The Emissions Gap Report 2014

    DEFF Research Database (Denmark)

    Farrell, Timothy Clifford

    This fifth Emissions Gap report has a different focus from previous years. While it updates the 2020 emissions gap analysis, it gives particular attention to the implications of the global carbon dioxide emissions budget for staying within the 2 °C limit beyond 2020. It does so because countries ...... are giving increasing attention to where they need to be in 2025, 2030 and beyond. Furthermore, this year’s update of the report benefits from the findings on the emissions budget from the latest series of Intergovernmental Panel on Climate Change (IPCC) reports...

  12. On-road remote sensing of CO and HC emissions in California. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stedman, D.H.; Bishop, G.A.; Beaton, S.P.; Peterson, J.E.; Guenther, P.L.

    1994-02-01

    The University of Denver used its remote sensor for motor vehicle CO and HC emissions to measure the tailpipe concentrations of over 90,000 California Vehicles in a 30-day period in 1991. The study consisted of three phases; a series of controlled tests, a pullover study of high-emitters, and a series of measurements at a variety of sites around the South Coast Air Basin and northern California. The highest CO emissions occurred under hard accelerations, while the highest HC emissions occurred during decelarations. In the pullover study, over 92% of the vehicles identified as high emitters failed the roadside inspection, equivalent to a California Smog Check. More than 60% of the vehicles stopped had defective emission control equipment (over 40% were tampered). The highest emitting vehicles showed the most variability in their emissions. This variability carries implications for the design of inspection and maintenance programs.

  13. The time variation in infrared water-vapour bands in Mira variables

    NARCIS (Netherlands)

    Matsuura, M; Yamamura, [No Value; Cami, J; Onaka, T; Murakami, H; Yamamura, I.

    The time variation in the water-vapour bands in oxygen-rich Mira variables has been investigated using multi-epoch ISO/SWS spectra of four Mira variables in the 2.5-4.0 mum region. All four stars show H2O bands in absorption around minimum in the visual light curve. At maximum, H2O emission features

  14. Variability of Spectral Energy Distribution of Blazar S5 0716+ 714

    Indian Academy of Sciences (India)

    The emission from blazars is known to be variable at all wavelengths. The flux variability is often accompanied by spectral changes. Spectral energy distribution (SED) changes must be associated with changes in the spectra of emitting electrons and/or the physical parameters of the jet. Meaningful modeling of blazar ...

  15. The impact of CO2 emissions on economic growth: evidence from selected higher CO2 emissions economies.

    Science.gov (United States)

    Azam, Muhammad; Khan, Abdul Qayyum; Bin Abdullah, Hussin; Qureshi, Muhammad Ejaz

    2016-04-01

    The main purpose of this work is to analyze the impact of environmental degradation proxied by CO2 emissions per capita along with some other explanatory variables namely energy use, trade, and human capital on economic growth in selected higher CO2 emissions economies namely China, the USA, India, and Japan. For empirical analysis, annual data over the period spanning between 1971 and 2013 are used. After using relevant and suitable tests for checking data properties, the panel fully modified ordinary least squares (FMOLS) method is employed as an analytical technique for parameter estimation. The panel group FMOLS results reveal that almost all variables are statistically significant, whereby test rejects the null hypotheses of non cointegration, demonstrating that all variables play an important role in affecting the economic growth role across countries. Where two regressors namely CO2 emissions and energy use show significantly negative impacts on economic growth, for trade and human capital, they tend to show the significantly positive impact on economic growth. However, for the individual analysis across countries, the panel estimate suggests that CO2 emissions have a significant positive relationship with economic growth for China, Japan, and the USA, while it is found significantly negative in case of India. The empirical findings of the study suggest that appropriate and prudent policies are required in order to control pollution emerging from areas other than liquefied fuel consumption. The ultimate impact of shrinking pollution will help in supporting sustainable economic growth and maturation as well as largely improve society welfare.

  16. Exhaust emissions of DI diesel engine using unconventional fuels

    Science.gov (United States)

    Sudrajad, Agung; Ali, Ismail; Hamdan, Hazmie; Hamzah, Mohd. Herzwan

    2012-06-01

    Optimization of using waste plastic and tire disposal fuel on diesel engine were observed. The experimental project was comparison between using both of unconventional fuel and base diesel fuel. The engine experiment was conducted with YANMAR TF120 single cylinder four stroke diesel engine set-up at variable engine speed at 2100, 1900, 1700, 1500 and 1300 rpm. The data have been taken at each point of engine speed during the stabilized engine-operating regime. Measurement of emissions parameters at different engine speed conditions have generally indicated lower in emission COfor waste plastic fuel, lower NOx for tire disposal fuel and lower SOx for diesel fuel.

  17. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...... rest-frame 0.1-5 µm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most...

  18. Emissivity independent optical pyrometer

    Science.gov (United States)

    Earl, Dennis Duncan; Kisner, Roger A.

    2017-04-04

    Disclosed herein are representative embodiments of methods, apparatus, and systems for determining the temperature of an object using an optical pyrometer. Certain embodiments of the disclosed technology allow for making optical temperature measurements that are independent of the surface emissivity of the object being sensed. In one of the exemplary embodiments disclosed herein, a plurality of spectral radiance measurements at a plurality of wavelengths is received from a surface of an object being measured. The plurality of the spectral radiance measurements is fit to a scaled version of a black body curve, the fitting comprising determining a temperature of the scaled version of the black body curve. The temperature is then output. The present disclosure is not to be construed as limiting and is instead directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone or in various combinations and subcombinations with one another.

  19. Positron emission mammography imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.

    2003-10-02

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and x-ray mammography, as well as PEM and x-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  20. 47 CFR 78.103 - Emissions and emission limitations.

    Science.gov (United States)

    2010-10-01

    ...: At least 25 decibels below the mean power of the emission; (ii) On any frequency above the upper... authorized channel width: At least 35 decibels below the mean power of the emission; and (iii) On any... authorized channel width: At least 43+10 log1 0 (power in watts) decibels below the mean power of the...

  1. An inventory of the emission of ammonia from agricultural fertilizer application in China for 2010 and its high-resolution spatial distribution

    NARCIS (Netherlands)

    Xu, Peng; Zhang, Yisheng; Gong, Weiwei; Hou, Xikang; Kroeze, Carolien; Gao, Wei; Luan, Shengji

    2015-01-01

    In an agricultural county like China, agricultural fertilizers are the source of ammonia (NH3) emissions. However, the spatial variability in NH3 emissions is large, and the associated uncertainties affect the reliability of total NH3 emission estimates. In this

  2. Regularization by External Variables

    DEFF Research Database (Denmark)

    Bossolini, Elena; Edwards, R.; Glendinning, P. A.

    2016-01-01

    Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula...... of regularization, by external variables that shadow either the state or the switch of the original system. The shadow systems are derived from and inspired by various applications in electronic control, predator-prey preference, time delay, and genetic regulation....

  3. Atmospheric Infrared Radiance Variability.

    Science.gov (United States)

    1981-05-27

    ATMOSPHERIC VARIABILITY ON INFRARED RADIANCE PREDICTIONS - T. C. Degges 53 5. ATMOSPHERIC STRUCTURE - C.H. HLmphrey, C.R. Philbrick, S.M. Silverman , T.F. Tuan...variations similar to those shown in Figure 2. In arctic and subarctic regions, sudden warmings and coolings of the winter stratosphere and mesosphere... Silverman \\Jr I",rre. (;.L~~sIalmratorN Hanscom Air Force Base, Manss. T.F. Tuan Universitv of Cincinnati Cincinnati, (tio M. Anapol S.S.G.. Inc. Waltham

  4. Variable camshaft timing system

    Energy Technology Data Exchange (ETDEWEB)

    Butterfield, R.P.; Smith, F.R.

    1989-09-05

    This patent describes an improvement in a variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of the intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshaft, only one of the camshafts being directly driven by an engine crankshaft, and a timing chain engaging both sprockets. The improvement comprising a single bracket carrying at least one idler sprocket engaging the timing chain, the bracket being mounted for movement to alter the timing relationship between the intake and exhaust sprockets.

  5. Complex variables II essentials

    CERN Document Server

    Solomon, Alan D

    2013-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Complex Variables II includes elementary mappings and Mobius transformation, mappings by general functions, conformal mappings and harmonic functions, applying complex functions to a

  6. Variation in enteric methane emissions among cows on commercial dairy farms.

    Science.gov (United States)

    Bell, M J; Potterton, S L; Craigon, J; Saunders, N; Wilcox, R H; Hunter, M; Goodman, J R; Garnsworthy, P C

    2014-09-01

    Methane (CH4) emissions by dairy cows vary with feed intake and diet composition. Even when fed on the same diet at the same intake, however, variation between cows in CH4 emissions can be substantial. The extent of variation in CH4 emissions among dairy cows on commercial farms is unknown, but developments in methodology now permit quantification of CH4 emissions by individual cows under commercial conditions. The aim of this research was to assess variation among cows in emissions of eructed CH4 during milking on commercial dairy farms. Enteric CH4 emissions from 1964 individual cows across 21 farms were measured for at least 7 days/cow using CH4 analysers at robotic milking stations. Cows were predominantly of Holstein Friesian breed and remained on the same feeding systems during sampling. Effects of explanatory variables on average CH4 emissions per individual cow were assessed by fitting a linear mixed model. Significant effects were found for week of lactation, daily milk yield and farm. The effect of milk yield on CH4 emissions varied among farms. Considerable variation in CH4 emissions was observed among cows after adjusting for fixed and random effects, with the CV ranging from 22% to 67% within farms. This study confirms that enteric CH4 emissions vary among cows on commercial farms, suggesting that there is considerable scope for selecting individual cows and management systems with reduced emissions.

  7. Emissivity measurement of high-emissivity black paint at CENAM

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas G, D., E-mail: dcardena@cenam.mx [Centro Nacional de Metrologia, Km 4.5 Carretera a los Cues, El Marques, 76246 Santiago de Queretaro, Queretaro (Mexico)

    2014-07-01

    To measure the temperature of the surface of an opaque object by radiation thermometry, it is necessary to know its surface emissivity. High emissivity black paint can be applied to the inner walls of a cavity to be used as a blackbody radiator. It can also be applied to some highly reflecting metals so that their temperature can be estimated by radiation thermometry. In this work, it is described the emissivity measurement of high-emissivity black paint that has been used for the two applications described above. The average emissivity of the measured paint in the 8 to 14 micrometers wavelength range was estimated as 0.972 ± 0.012. The results obtained may be of use for those using the paint at temperatures from 50 to 150 grades C. (Author)

  8. Derivation of motor vehicle tailpipe particle emission factors suitable for modelling urban fleet emissions and air quality assessments.

    Science.gov (United States)

    Keogh, Diane U; Kelly, Joe; Mengersen, Kerrie; Jayaratne, Rohan; Ferreira, Luis; Morawska, Lidia

    2010-03-01

    Urban motor vehicle fleets are a major source of particulate matter pollution, especially of ultrafine particles (diameters vehicle particle emission factors derived using a wide range of different measurement methods for different particle sizes, conducted in different parts of the world. Therefore, the choice as to which are the most suitable particle emission factors to use in transport modelling and health impact assessments presented as a very difficult task. The aim of this study was to derive a comprehensive set of tailpipe particle emission factors for different vehicle and road type combinations, covering the full size range of particles emitted, which are suitable for modelling urban fleet emissions. A large body of data available in the international literature on particle emission factors for motor vehicles derived from measurement studies was compiled and subjected to advanced statistical analysis, to determine the most suitable emission factors to use in modelling urban fleet emissions. This analysis resulted in the development of five statistical models which explained 86%, 93%, 87%, 65% and 47% of the variation in published emission factors for particle number, particle volume, PM(1), PM(2.5) and PM(10), respectively. A sixth model for total particle mass was proposed but no significant explanatory variables were identified in the analysis. From the outputs of these statistical models, the most suitable particle emission factors were selected. This selection was based on examination of the statistical robustness of the statistical model outputs, including consideration of conservative average particle emission factors with the lowest standard errors, narrowest 95% confidence intervals and largest sample sizes and the explanatory model variables, which were vehicle type (all particle metrics), instrumentation (particle number and PM(2.5)), road type (PM(10)) and size range measured and speed limit on the road (particle volume). A multiplicity of

  9. Solar flare impulsive phase emission observed with SDO/EVE

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, Michael B.; Milligan, Ryan O.; Mathioudakis, Mihalis; Keenan, Francis P., E-mail: mkennedy29@qub.ac.uk [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, University Road, Belfast BT7 1NN (United Kingdom)

    2013-12-10

    Differential emission measures (DEMs) during the impulsive phase of solar flares were constructed using observations from the EUV Variability Experiment (EVE) and the Markov-Chain Monte Carlo method. Emission lines from ions formed over the temperature range log T{sub e} = 5.8-7.2 allow the evolution of the DEM to be studied over a wide temperature range at 10 s cadence. The technique was applied to several M- and X-class flares, where impulsive phase EUV emission is observable in the disk-integrated EVE spectra from emission lines formed up to 3-4 MK and we use spatially unresolved EVE observations to infer the thermal structure of the emitting region. For the nine events studied, the DEMs exhibited a two-component distribution during the impulsive phase, a low-temperature component with peak temperature of 1-2 MK, and a broad high-temperature component from 7 to 30 MK. A bimodal high-temperature component is also found for several events, with peaks at 8 and 25 MK during the impulsive phase. The origin of the emission was verified using Atmospheric Imaging Assembly images to be the flare ribbons and footpoints, indicating that the constructed DEMs represent the spatially average thermal structure of the chromospheric flare emission during the impulsive phase.

  10. Global Occurrence and Emission of Rotaviruses to Surface Waters

    Directory of Open Access Journals (Sweden)

    Nicholas M. Kiulia

    2015-05-01

    Full Text Available Group A rotaviruses (RV are the major cause of acute gastroenteritis in infants and young children globally. Waterborne transmission of RV and the presence of RV in water sources are of major public health importance. In this paper, we present the Global Waterborne Pathogen model for RV (GloWPa-Rota model to estimate the global distribution of RV emissions to surface water. To our knowledge, this is the first model to do so. We review the literature to estimate three RV specific variables for the model: incidence, excretion rate and removal during wastewater treatment. We estimate total global RV emissions to be 2 × 1018 viral particles/grid/year, of which 87% is produced by the urban population. Hotspot regions with high RV emissions are urban areas in densely populated parts of the world, such as Bangladesh and Nigeria, while low emissions are found in rural areas in North Russia and the Australian desert. Even for industrialized regions with high population density and without tertiary treatment, such as the UK, substantial emissions are estimated. Modeling exercises like the one presented in this paper provide unique opportunities to further study these emissions to surface water, their sources and scenarios for improved management.

  11. Climate regulation of fire emissions and deforestation in equatorial Asia.

    Science.gov (United States)

    van der Werf, G R; Dempewolf, J; Trigg, S N; Randerson, J T; Kasibhatla, P S; Giglio, L; Murdiyarso, D; Peters, W; Morton, D C; Collatz, G J; Dolman, A J; DeFries, R S

    2008-12-23

    Drainage of peatlands and deforestation have led to large-scale fires in equatorial Asia, affecting regional air quality and global concentrations of greenhouse gases. Here we used several sources of satellite data with biogeochemical and atmospheric modeling to better understand and constrain fire emissions from Indonesia, Malaysia, and Papua New Guinea during 2000-2006. We found that average fire emissions from this region [128 +/- 51 (1sigma) Tg carbon (C) year(-1), T = 10(12)] were comparable to fossil fuel emissions. In Borneo, carbon emissions from fires were highly variable, fluxes during the moderate 2006 El Niño more than 30 times greater than those during the 2000 La Niña (and with a 2000-2006 mean of 74 +/- 33 Tg C yr(-1)). Higher rates of forest loss and larger areas of peatland becoming vulnerable to fire in drought years caused a strong nonlinear relation between drought and fire emissions in southern Borneo. Fire emissions from Sumatra showed a positive linear trend, increasing at a rate of 8 Tg C year(-2) (approximately doubling during 2000-2006). These results highlight the importance of including deforestation in future climate agreements. They also imply that land manager responses to expected shifts in tropical precipitation may critically determine the strength of climate-carbon cycle feedbacks during the 21st century.

  12. Airborne Methane Emission Measurements for Selected Oil and Gas Facilities Across California.

    Science.gov (United States)

    Mehrotra, Shobhit; Faloona, Ian C; Suard, Maxime; Conley, Stephen A; Fischer, Marc L

    2017-10-11

    We report 65 individual measurements of methane emissions from 24 oil & gas facilities across California. Methane emission rates were estimated using in-situ methane and wind velocity measurements from a small aircraft by a novel Gauss' Theorem flux integral approach. The estimates are compared with annual mean emissions reported to the US-EPA and the California Air Resources Board (CARB) through their respective greenhouse gas reporting programs. The average emissions from 36 measurements of 10 gas storage facilities were within a factor of 2 of emissions reported to US-EPA or CARB, though large variance was observed and the reporting database did not contain all of the facilities. In contrast, average emissions from 15 measurements of the three refineries were roughly an order of magnitude more than reported to the US-EPA or CARB. The remaining measurements suggest compressor emissions are variable and perhaps slightly larger than reported, and emissions from one oil production facility were roughly concordant with a separate (not GHG reporting) bottom-up estimate from other work. Together, these results provide an initial facility-specific survey of methane emissions from California oil and natural gas infrastructure with observed variability suggesting the need for expanded measurements in the future.

  13. A synthesis of growing-season and annual methane emissions among temperate, boreal, and arctic wetlands

    Science.gov (United States)

    Treat, Claire

    2017-04-01

    Wetlands are the largest natural source of methane to the atmosphere, but predicting methane emissions from wetlands using process-based modeling remains challenging due to the decoupling between production and emission. Furthermore, methane emissions are highly variable among sites, years, and temporal scales due to differences in production, oxidation, and transport pathways. Here, I synthesize growing season, non-growing season, and annual methane emissions from chamber and eddy-covariance measurements for >150 sites in undisturbed temperate, boreal, and arctic wetlands and adjacent uplands. I compare the magnitude of fluxes among regions, wetland classifications, vegetation classifications, environmental variables, and measurement methods. Growing season measurements were most abundant in bogs, fens, and tundra sites, while marshes, swamps, and permafrost thaw features were relatively undersampled. Methane emissions were largest from intermediate and rich fens (> 15 g CH4 m-2 y-1) and lowest from upland mineral soils and polygonal tundra (≤ 3 g CH4 m-2 y-1). Non-growing season emissions accounted for 20% of annual methane emissions. Across all sites, there were no significant differences in growing season methane emissions between autochambers, manual chambers, and eddy covariance. These results provide constraints for methane emissions from temporal, boreal, and arctic wetlands utilizing the numerous flux measurements conducted over the past 25 years.

  14. Using Variable Speed Control on Pump Application

    Directory of Open Access Journals (Sweden)

    Dr.Sc. Aida Spahiu

    2012-06-01

    Full Text Available Pumps are one of the most common variable speed drive (VSD system applications and special interest has focused on improving their energy efficiency by using variable speed control instead of throttling or other less efficient flow control methods. Pumps are the single largest user of electricity in industry in the European Union, consuming 160 TWh per annum of electricity and accounting for 79 million tonnes of carbon dioxide (CO2 emissions [1]. Centrifugal pumps are the most likely pump style to provide a favorable return based on energy savings when applied with a variable speed drive. To help illustrate this, are conducted benchmark testing to document various head and flow scenarios and their corresponding effect on energy savings. Paper shows the relationship of static and friction head in the energy efficiency equation and the effect of motor, pump and VSD efficiencies. The received results are good reference points for engineers and managers of water sector in Albania to select the best prospects for maximizing efficiency and energy savings.

  15. Glycemic variability: Clinical implications

    Directory of Open Access Journals (Sweden)

    Surabhi Venkata Satya Krishna

    2013-01-01

    Full Text Available Glycemic control and its benefits in preventing microvascular diabetic complications are convincingly proved by various prospective trials. Diabetes control and complications trial (DCCT had reported variable glycated hemoglobin (HbA1C as a cause of increased microvascular complications in conventional glycemic control group versus intensive one. However, in spite of several indirect evidences, its link with cardiovascular events or macrovascular complications is still not proved. Glycemic variability (GV is one more tool to explain relation between hyperglycemia and increased cardiovascular risk in diabetic patients. In fact GV along with fasting blood sugar, postprandial blood sugar, HbA1C, and quality of life has been proposed to form glycemic pentad, which needs to be considered in diabetes management. Postprandial spikes in blood glucose as well as hypoglycemic events, both are blamed for increased cardiovascular events in Type 2 diabetics. GV includes both these events and hence minimizing GV can prevent future cardiovascular events. Modern diabetes management modalities including improved sulfonylureas, glucagon like peptide-1 (GLP-1-based therapy, newer basal insulins, and modern insulin pumps address the issue of GV effectively. This article highlights mechanism, clinical implications, and measures to control GV in clinical practice.

  16. Score test variable screening.

    Science.gov (United States)

    Zhao, Sihai Dave; Li, Yi

    2014-12-01

    Variable screening has emerged as a crucial first step in the analysis of high-throughput data, but existing procedures can be computationally cumbersome, difficult to justify theoretically, or inapplicable to certain types of analyses. Motivated by a high-dimensional censored quantile regression problem in multiple myeloma genomics, this article makes three contributions. First, we establish a score test-based screening framework, which is widely applicable, extremely computationally efficient, and relatively simple to justify. Secondly, we propose a resampling-based procedure for selecting the number of variables to retain after screening according to the principle of reproducibility. Finally, we propose a new iterative score test screening method which is closely related to sparse regression. In simulations we apply our methods to four different regression models and show that they can outperform existing procedures. We also apply score test screening to an analysis of gene expression data from multiple myeloma patients using a censored quantile regression model to identify high-risk genes. © 2014, The International Biometric Society.

  17. Artificial neural network-based predictive emission monitoring system for NOx emissions

    Energy Technology Data Exchange (ETDEWEB)

    Ciccone, A.; Cinnamon, C.; Niejadlik, P.R. [TransCanada Energy Ltd., Toronto, ON (Canada)]|[Golder Associates, Toronto, ON (Canada)

    2005-07-01

    Considering the nature of long term power supply contracts that do not include mechanisms for cost recovery, developing cost-effective ways to handle changes in legislation impacting on facilities already in operation is extremely important. Also of importance is the age of the facilities, since continuous emissions monitoring (CEM) systems were not required when they were originally put into operation, but they are not yet old enough for capital stock turnover to allow for equipment changes or transition to new operations. An alternative monitoring method that is less expensive and as accurate as traditional (CEM) systems is discussed. TransCanada Energy Ltd., developed a predictive emission monitoring (PEM) system that achieved the required accuracy of the regulatory authorities using four of its gas turbine power plant facilities. Using the power plant operation variables to predict the nitric oxide (NO) portion of the exhaust emissions, the systems are founded on an artificial neural network (ANN). This paper provides a summary of the PEM system architecture and provides background information on the facilities used in the development of this approach. It was concluded that the PEM system provides a cost effective method to monitor emissions accurately and reliably at low emitting natural gas fired facilities. As well, there is a great potential for the system to be used by other industries to monitor and report emissions. The PEM system is an ideal system for the low emitting natural gas fired generating plants however the system could be adapted for other types of industries. 5 refs., 5 tabs., 2 figs.

  18. NORTRIP emission model user guide

    Energy Technology Data Exchange (ETDEWEB)

    Denby, Rolstad Bruce

    2012-07-01

    The NORTRIP emission model has been developed at NILU, in conjunction with other Nordic institutes, to model non-exhaust traffic induced emissions. This short summary document explains how to run the NORTRIP model from the MATLAB environment or by using the executable user interface version. It also provides brief information on input files and the model architecture.(Author)

  19. The Emissions Gap Report 2012

    NARCIS (Netherlands)

    Vuuren, D.P. van

    2012-01-01

    One of the fundamental questions in the global climate negotiations is: what level of “ambition”, in terms of collective emission reductions, is needed to protect global climate? To help answer this question UNEP and the scientific community have published a series of reports on the “emissions

  20. Emission of formaldehyde from furniture

    DEFF Research Database (Denmark)

    Andersen, Helle Vibeke; Klinke, Helene B.; Funch, Lis Winther

    The emission of formaldehyde from 20 pieces of furniture, representing a variety of types, was measured in climate chambers. Most tests show low emissions but certain scenarios of furnishing, including furniture with large surface areas in relation to room volume can emit formaldehyde resulting...

  1. DOES ELECTRIC CAR PRODUCE EMISSIONS?

    Directory of Open Access Journals (Sweden)

    Vladimír RIEVAJ

    2017-03-01

    Full Text Available This article focuses on the comparison of the amount of emissions produced by vehicles with a combustion engine and electric cars. The comparison, which is based on the LCA factor results, indicates that an electric car produces more emissions than a vehicle with combustion engine. The implementation of electric cars will lead to an increase in the production of greenhouse gases.

  2. Research priorities for negative emissions

    NARCIS (Netherlands)

    Fuss, S.; Jones, C. D.; Kraxner, F.; Peters, G. P.; Smith, P.; Tavoni, M.; van Vuuren, Detlef|info:eu-repo/dai/nl/11522016X; Canadell, J. G.; Jackson, R. B.; Milne, J.; Moreira, J. R.; Nakicenovic, N.; Sharifi, A.; Yamagata, Y.

    2016-01-01

    Carbon dioxide removal from the atmosphere (CDR) - also known as 'negative emissions' - features prominently in most 2 °C scenarios and has been under increased scrutiny by scientists, citizens, and policymakers. Critics argue that 'negative emission technologies' (NETs) are insufficiently mature to

  3. Estimating impacts of emission specific characteristics on vehicle operation for quantifying air pollutant emissions and energy use

    Directory of Open Access Journals (Sweden)

    K.S. Nesamani

    2017-06-01

    Full Text Available This paper proposes and illustrates a methodology to predict the fraction of time motor vehicles spend in different operating conditions from readily observable variables called emission specific characteristics (ESC. ESC describe salient characteristics of vehicles, roadway geometry, the roadside environment, traffic, and driving style (aggressive, normal, and calm. The information generated by our methodology can then be entered in vehicular emission models that rely on vehicle specific power, i.e., comprehensive modal emissions model (CMEM, international vehicle emissions (IVE, or motor vehicle emission simulator (MOVES to compute energy consumption and vehicular emissions for various air pollutants. After generating second-by-second vehicle trajectories from a calibrated micro-simulation model, the authors estimated structural equation models to examine the influence of link ESC on vehicle operation. Authors' results show that 67% of the link speed variance is explained by ESC. Overall, the roadway geometry exerts a greater influence on link speed than traffic characteristics, the roadside environment, and driving style. Moreover, the speed limit has the strongest influence on vehicle operation, followed by facility type and driving style. Better understanding the impact on vehicle operation of ESC could help metropolitan planning organizations (MPOs and regional transportation authorities predict vehicle operations and reduce the environmental footprint of motor vehicles.

  4. Emission of formaldehyde from furniture

    DEFF Research Database (Denmark)

    Andersen, Helle Vibeke; Klinke, Helene B.; Funch, Lis Winther

    2014-01-01

    The emission of formaldehyde from a variety of furniture was measured in climate chambers. Most tests show low emission of formaldehyde; however, there are a few exceptions. One product emitted significant amounts of formaldehyde, but according to the Danish Indoor Climate Labelling Criteria...... for furniture the impact on the formaldehyde concentration was low due to a small surface area in the standard room. One product led to a high concentration of formaldehyde in the standard room since both emission and material load were high. Even with a moderate area-specific emission rate of formaldehyde......, furniture with high material load in the standard room, such as bookcases, can have a significant impact on the indoor air. The results showed that furniture on the Danish market may have an emission of formaldehyde resulting in indoor concentrations above the WHO recommended limit of 0.1 mg m-3. Therefore...

  5. Nanoparticle emissions from combustion engines

    CERN Document Server

    Merkisz, Jerzy

    2015-01-01

     This book focuses on particulate matter emissions produced by vehicles with combustion engines. It describes the physicochemical properties of the particulate matter, the mechanisms of its formation and its environmental impacts (including those on human beings). It discusses methods for measuring particulate mass and number, including the state-of-the-art in Portable Emission Measurement System (PEMS) equipment for measuring the exhaust emissions of both light and heavy-duty vehicles and buses under actual operating conditions. The book presents the authors’ latest investigations into the relations between particulate emission (mass and number) and engine operating parameters, as well as their new findings obtained through road tests performed on various types of vehicles, including those using diesel particulate filter regeneration. The book, which addresses the needs of academics and professionals alike, also discusses relevant European regulations on particulate emissions and highlights selected metho...

  6. Deliberating emission reduction options

    Energy Technology Data Exchange (ETDEWEB)

    Dowd, A.M.; Rodriguez, M.; Jeanneret, T. [Commonwealth Scientific and Industrial Research Organisation CSIRO, 37 Graham Rd, Highett VIC 3190 (Australia); De Best-Waldhober, M.; Straver, K.; Mastop, J.; Paukovic, M. [Energy research Centre of the Netherlands ECN, Policy Studies, Amsterdam (Netherlands)

    2012-06-15

    For more than 20 years there has been a concerted international effort toward addressing climate change. International conventions, such as the United Nations Foreign Convention on Climate Change (UNFCCC; ratified in 1994), have been established by committed nations seeking to address global climate change through the reduction of greenhouse gases emitted into the Earth's atmosphere (Global CCS Institute, 2011). Long recognised as the most crucial of the greenhouse gases to impact global warming, the majority of carbon dioxide's anthropogenic global emissions are directly related to fuel combustion of which both Australia and the Netherlands' energy production is significantly reliant. Both these nations will need to consider many opinions and make hard decisions if alternative energy options are to be implemented at the scale that is required to meet international emission targets. The decisions that are required not only need to consider the many options available but also their consequences. Along with politicians, policy developers and industry, the general public also need to be active participants in deciding which energy options, and their subsequent consequences, are acceptable for implementation at the national level. Access to balanced and factual information is essential in establishing informed opinions on the many policy options available. Past research has used several methods to measure public perceptions and opinions yet for complex issues, such as emission reduction, some of these methods have shown to be problematic. For example, semi structured interviews can provide data that is flexible and context rich yet is does also come with the limitations such as it seldom provides a practical assessment that can be utilised from researcher to researcher, across disciplines and public participation techniques. Surveys on the other hand usually address these limitations but surveys that do not encourage comparison of information or ask

  7. U.S. broiler housing ammonia emissions inventory

    Science.gov (United States)

    Gates, R. S.; Casey, K. D.; Wheeler, E. F.; Xin, H.; Pescatore, A. J.

    Using recently published baseline ammonia emissions data for U.S. broiler chicken housing, we present a method of estimating their contribution to an annual ammonia budget that is different from that used by USEPA. Emission rate increases in a linear relationship with flock age from near zero at the start of the flock to a maximum at the end of the flock, 28-65 days later. Market weight of chickens raised for meat varies from "broilers" weighing about 2 kg to "roasters" weighing about 3 kg. Multiple flocks of birds are grown in a single house annually, with variable downtime to prepare the house between flocks. The method takes into account weight and number of chickens marketed. Uncertainty in baseline emissions estimates is used so that inventory estimates are provided with error estimates. The method also incorporates the condition of litter that birds are raised upon and the varying market weight of birds grown. Using 2003 USDA data on broiler production numbers, broiler housing is estimated to contribute 8.8-11.7 kT ammonia for new and built-up litter, respectively, in Kentucky and 240-324 kT ammonia for new and built-up litter, respectively, nationally. Results suggest that a 10% uncertainty in annual emission rate is expected for the market weight categories of broilers, heavy broilers, and roasters. A 27-47% reduction in annual housing emission rate is predicted if new rather than built-up litter were used for every flock. The estimating method can be adapted to other meat bird building emissions and future ammonia emission strategies, with suitable insertion of an age-dependent emission factor or slope into a predictive model equation. The method can be readily applied and is an alternative to that used by USEPA.

  8. Chatter Prediction for Variable Pitch and Variable Helix Milling

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2015-01-01

    Full Text Available Regenerative chatter is a self-excited vibration that can occur during milling, which shortens the lifetime of the tool and results in unacceptable surface quality. In this paper, an improved semidiscretization method for modeling and simulation with variable pitch and variable helix milling is proposed. Because the delay between each flute varies along the axial depth of the tool in milling, the cutting tool is discrete into some axial layers to simplify calculation. A comparison of the predicted and observed performance of variable pitch and variable helix against uniform pitch and uniform helix milling is presented. It is shown that variable pitch and variable helix milling can obtain larger stable cutting area than uniform pitch and uniform helix milling. Thus, it is concluded that variable pitch and variable helix milling are an effective way for suppressing chatter.

  9. COAL DUST EMISSION PROBLEM

    Directory of Open Access Journals (Sweden)

    M. M. Biliaiev

    2016-12-01

    Full Text Available Purpose. The article aims to develop 2D numerical models for the prediction of atmospheric pollution during transportation of coal in the railway car, as well as the ways to protect the environment and the areas near to the mainline from the dust emission due to the air injection installation. Methodology. To solve this problem there were developed numerical models based on the use of the equations of motion of an inviscid incompressible fluid and mass transfer. For the numerical integration of the transport equation of the pollutant the implicit alternating-triangular difference scheme was used. For numerical integration of the 2D equation for the velocity potential the method of total approximation was used. The developed numerical models are the basis of established software package. On the basis of the constructed numerical models it was carried out a computational experiment to assess the level of air pollution when transporting bulk cargo by rail when the railway car has the air injection. Findings. 2D numerical models that belong to the class «diagnostic models» were developed. These models take into account the main physical factors affecting the process of dispersion of dust pollution in the atmosphere during transportation of bulk cargo. The developed numerical models make it possible to calculate the dust loss process, taking into account the use of the air injection of the car. They require a small cost of the computer time during practical realization at the low and medium power machines. There were submitted computational calculations to determine pollutant concentrations and the formation of the zone of pollution near the train with bulk cargo in «microscale» scale taking into account the air curtains. Originality. 2D numerical models taking into account the relevant factors influencing the process of dispersion of pollutants in the atmosphere, and the formation of the zone of pollution during transportation of bulk cargo by

  10. Variable cycle engine

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, A.P.; Sprunger, E.V.

    1980-09-16

    A variable cycle turboshaft engine includes a remote fan system and respective high and low pressure systems for selectively driving the fan system in such a manner as to provide VTOL takeoff capability and minimum specific fuel consumption (SFC) at cruise and loiter conditions. For takeoff the fan system is primarily driven by the relatively large low pressure system whose combustor receives the motive fluid from a core bypass duct and, for cruise and loiter conditions, the fan system is driven by both a relatively small high pressure core and the low pressure system with its combustor inoperative. A mixer is disposed downstream of the high pressure system for mixing the relatively cold air from the bypass duct and the relatively hot air from the core prior to its flow to the low pressure turbine.

  11. Variable Amplitude Fatigue

    Science.gov (United States)

    Ranganathan, Narayanaswami; Joly, Damien; Leroy, René

    Fatigue crack growth behavior of selected aluminum alloys under variable amplitude loading is discussed in this study, based principally on experimental observations. The tests include single overloads tests in different environments, block load tests and tests using an aircraft wing loading spectrum. It is shown that conditions favoring a planar slip behavior lead to very high delays as opposed to conditions leading to multiple slip behavior. The Aluminium Liithium alloy studied here, has the best fatigue crack growth resistance in almost all test conditions studied here as compared to other conventional alloys. Under the spectrum loading studied here, the same alloy exhibits a change in micromechanism leading to a four fould acceleration of growth rates. Acceptable life predictions can be made, by taking into account this crack acceleration effect.

  12. Pricing hazardous substance emissions

    Energy Technology Data Exchange (ETDEWEB)

    Staring, Knut; Vennemo, Haakon

    1997-12-31

    This report discusses pricing of emissions to air of several harmful substances. It combines ranking indices for environmentally harmful substances with economic valuation data to yield price estimates. The ranking methods are discussed and a relative index established. Given the relative ranking of the substances, they all become valued by assigning a value to one of them, the `anchor` substance, for which lead is selected. Valuations are provided for 19 hazardous substances that are often subject to environmental regulations. They include dioxins, TBT, etc. The study concludes with a discussion of other categories of substances as well as uncertainties and possible refinements. When the valuations are related to CO, NOx, SOx and PM 10, the index system undervalues these pollutants as compared to other studies. The scope is limited to the outdoor environment and does not include global warming and eutrophication. The indices are based on toxicity and so do not apply to CO{sub 2} or other substances that are biologically harmless. The index values are not necessarily valid for all countries and should be considered as preliminary. 18 refs., 6 tabs.

  13. Smoothed Emission for IMC

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, N A

    2011-01-24

    Here is a review of the current way we handle source photons in Implicit Monte Carlo (IMC). A source photon is created with a randomly sampled position x{sub p} in the zone, a direction {Omega}{sub p}, a frequency v{sub p} sampled from the appropriate distribution, and a time t{sub p} uniformly sampled from [t{sup n}, t{sup n+1}]. The source photons each have an energy E{sub p}. The sum of E{sub p} over all of the photons equals the energy of the source for that time step. In the case of thermal emission in a zone with Volume V, they would have {Sigma}{sub p=1}{sup N} E{sub p} = {sigma} {sub p}acT{sup 4}V{Delta}t, where N is the number of thermal source photons for that time step, and {sigma}{sub p} is the Planck mean opacity. Census photons do not differ from source photons in any way, except that they all start the time step with t{sub p} = t{sup n}. Then they advance each photon until it reaches the end of the time step. When they are done with all of the photons, they update the matter temperature using the difference between the emitted and absorbed energy, and proceed to the next time step.

  14. Factors Affecting Mitigation of Methane Emission from Ruminants: Management Strategies

    Directory of Open Access Journals (Sweden)

    Afshar Mirzaei-Aghsaghali

    2015-06-01

    Full Text Available Nowadays, greenhouse gas emission which results in elevating global temperature is an important subject of worldwide ecological and environmental concern. Among greenhouse gases, methane is considered a potent greenhouse gas with 21 times more global warming potential than carbon dioxide. Worldwide, ruminant livestock produce about 80 million metric tons of methane each year, accounting for about 28% of global emissions from human related activities. Therefore it is impelling animal scientists to finding solutions to mitigate methane emission from ruminants. It seems that solutions can be discussed in four topics including: nutrition (feeding, biotechnology, microbiology and management strategies. We have already published the first review article on feeding strategies. In the current review, management strategies such as emphasizing on animals - type and individual variability, reducing livestock numbers, improving animal productivity and longevity as well as pasture management; that can be leads to decreasing methane production from ruminant animal production are discussed.

  15. Copernicus observations of Ly-alpha and Mg II emission from HR 1099 /V711 Tauri/ and UX Ari

    Science.gov (United States)

    Weiler, E. J.

    1978-01-01

    Ultraviolet observations of two RS CVn binaries obtained with Copernicus are described. High-resolution (0.05 A) U1 observations indicate that both HR 1099 and UX Ari display broad Ly-alpha emission. The Ly-alpha emission strength from HR 1099 is variable and seems to be correlated with orbital phase, while the UX Ari results indicate no significant variation. Moderate resolution (0.51 A) V2 scans of both systems show variable Mg II h and k emission-line profiles which usually matched the velocity of the more active star in each binary. Additionally, displaced emission components were seen at velocities of up to + or - 250 km/s, indicative of high-velocity gas motions. The radial velocities of these emission features from HR 1099 are marginally correlated with orbital phase. Highly active and variable chromospheric phenomena are found to be the most consistent explanation of these results.

  16. Near-IR Spectral Variability of Be Stars

    Science.gov (United States)

    Cole, Austin; Eisner, J. A.; Rudolph, A. L.

    2013-01-01

    Be class stars exhibit variability across the electromagnetic spectrum, including in both the visible and infrared regions. While variability in the optical range has been explored previously, spectroscopic variability in the near-IR has not been investigated as thoroughly. This study is focused on tracking the spectral variability of K Dra, one of the Be stars for which we collected data. We observed our sample using the FSPEC instrument on the 90-inch Bok telescope at Kitt Peak. The data were collected during four five-night runs, two in 2010 separated by one month and two in 2011 also separated by one month. A reduction pipeline written in Interactive Data Language (IDL) was used to produce emission spectra of the star from these data. Here we present spectra from these epochs that show emission from the Brackett Gamma hydrogen transition. We use changes in these features to constrain variability in the Hydrogen gas comprising the disk of this star as a function of time.

  17. BVOC emission pattern from Quercus robur under field conditions

    Science.gov (United States)

    Pokorska, O.; Dewulf, J.; Joó; Šimpraga, M.; Steppe, K.; Amelynck, C.; Schoon, N.; Muller, J. J.; van Langenhove, H.

    2010-12-01

    tree-to-tree variability was assessed by comparing emissions of 3 different Quercus robur trees (QR 2, 3, 4) under the same conditions. Analyses have shown significant differences in emission strength of isoprene and monoterpenes as well as in emission pattern of monoterpenes. In August emission of isoprene from QR2 and QR3 was significantly lower than emission of QR4 (by factor of 2). Interestingly in October emission of isoprene from QR3 was 4 times higher than emission of QR2 and QR4; moreover the isoprene emission of QR2 stays at the same level as in August. Overall, results demonstrate that BVOC emissions from Quercus robur vary widely throughout seasons as well as from tree to tree. However, the values for isoprene seasonal variation found in the literature are in agreement with our results, the emission range of intra-species variability was not previously reported. We thank BELSPO (Belgian Science Policy; IMPECVOC contract # SD/TE/03A) and FWO (Fonds voor Wetenschappelijk Onderzoek; contract # B/07659/02) for supporting the research program. 1. J. Loathawornkitkul et al., New Phytol. 183 (2009).

  18. Reconfigurable wearable to monitor physiological variables and movement

    Science.gov (United States)

    Romero, Francisco J.; Morales, Diego P.; Castillo, Encarnación; García, Antonio; Tahmassebi, Amirhessam; Meyer-Baese, Anke

    2017-05-01

    This article presents a preliminary prototype of a wearable instrument for oxygen saturation and ECG monitoring. The proposed measuring system is based on the light reflection variability of a LED emission on the subject temple. Besides, the system has the capacity to incorporate electrodes to obtain ECG measurements. All measurements are stored and transmitted to a mobile device (tablet or smartphone) through a Bluetooth link.

  19. Kepler Observations of Rapid Optical Variability in Active Galactic Nuclei

    Science.gov (United States)

    Mushotzky, R. F.; Edelson, R.; Baumgartner, W. H.; Gandhi, P.

    2012-01-01

    Over three quarters in 2010 - 2011, Kepler monitored optical emission from four active galactic nuclei (AGN) with approx 30 min sampling, > 90% duty cycle and approx law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGN exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN variability models but seem consistent with first order MRI theoretical calculations of accretion disk fluctuations.

  20. Gait Variability and Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Michael J. Socie

    2013-01-01

    Full Text Available Gait variability, that is, fluctuations in movement during walking, is an indicator of walking function and has been associated with various adverse outcomes such as falls. In this paper, current research concerning gait variability in persons with multiple sclerosis (MS is discussed. It is well established that persons with MS have greater gait variability compared to age and gender matched controls without MS. The reasons for the increase in gait variability are not completely understood. Evidence indicates that disability level, assistive device use, attentional requirement, and fatigue are related to gait variability in persons with MS. Future research should address the time-evolving structure (i.e., temporal characteristics of gait variability, the clinical importance of gait variability, and underlying mechanisms that drive gait variability in individuals with MS.

  1. New Directions: GEIA’s 2020 Vision for Better Air Emissions Information

    Energy Technology Data Exchange (ETDEWEB)

    Frost, G. J.; Middleton, Paulette; Tarrason, Leonor; Granier, Claire; Guenther, Alex B.; Cardenas, B.; Denier van der Gon, Hugo; Janssens-Maenhout, Greet; Kaiser, Johannes W.; Keating, Terry; Klimont, Z.; Lamarque, Jean-Francois; Liousse, Catherine; Nickovic, S.; Ohara, Toshimasa; Schultz, Martin; Skiba, Ute; Wang, Y.

    2013-12-01

    We are witnessing a crucial change in how we quantify and understand emissions of greenhouse gases and air pollutants, with an increasing demand for science-based transparent emissions information produced by robust community efforts. Today’s scientific capabilities, with near-real-time in-situ and remote sensing observations combined with forward and inverse models and a better understanding of the controlling processes, are contributing to this transformation and providing new approaches to derive, verify, and forecast emissions (Tong et al., 2011; Frost et al., 2012) and to quantify their impacts on the environment (e.g., Bond et al., 2013). At the same time, the needs for emissions information and the demands for their accuracy and consistency have grown. Changing economies, demographics, agricultural practices, and energy sources, along with mandates to evaluate emissions mitigation efforts, demonstrate compliance with legislation, and verify treaties, are leading to new challenges in emissions understanding. To quote NOAA Senior Technical Scientist David Fahey, "We are in the Century of Accountability. Emissions information is critical not only for environmental science and decision-making, but also as an instrument of foreign policy and international diplomacy." Emissions quantification represents a key step in explaining observed variability and trends in atmospheric composition and in attributing these observed changes to their causes. Accurate emissions data are necessary to identify feasible controls that reduce adverse impacts associated with air quality and climate and to track the success of implemented policies. To progress further, the international community must improve the understanding of drivers and contributing factors to emissions, and it must strengthen connections among and within different scientific disciplines that characterize our environment and entities that protect the environment and influence further emissions. The Global

  2. Advanced Collaborative Emissions Study (ACES)

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Daniel; Costantini, Maria; Van Erp, Annemoon; Shaikh, Rashid; Bailey, Brent; Tennant, Chris; Khalek, Imad; Mauderly, Joe; McDonald, Jacob; Zielinska, Barbara; Bemis, Jeffrey; Storey, John; Hallberg, Lance; Clark, Nigel

    2013-12-31

    The objective of the Advanced Collaborative Emissions Study (ACES) was to determine before widespread commercial deployment whether or not the new, energy-efficient, heavy duty diesel engines (2007 and 2010 EPA Emissions Standards Compliant) may generate anticipated toxic emissions that could adversely affect the environment and human health. ACES was planned to take place in three phases. In Phase 1, extensive emissions characterization of four production-intent prototype engine and control systems designed to meet 2007 standards for nitrogen oxides (NOx) and particulate matter (PM) was conducted at an existing emissions characterization facility: Southwest Research Institute (SwRI). One of the tested engines was selected (at random, after careful comparison of results) for health testing in Phase 3. In Phase 2, extensive emission characterization of three production-intent prototype engine and control systems meeting the 2010 standards (including more advanced NOx controls to meet the more stringent 2010 NOx standards) was conducted at the same test facility. In Phase 3, one engine/aftertreatment system selected from Phase 1 was further characterized during health effects studies (at an existing inhalation toxicology laboratory: Lovelace Respiratory Research Institute, [LRRI]) to form the basis of the ACES safety assessment. The Department of Energy (DOE) award provided funding for emissions characterization in Phases 1 and 2 as well as exposure characterization in Phase 3. The main health analyses in Phase 3 were funded separately and are not reported here.

  3. Optical antenna enhanced spontaneous emission.

    Science.gov (United States)

    Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

    2015-02-10

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

  4. Modeling Shared Variables in VHDL

    DEFF Research Database (Denmark)

    Madsen, Jan; Brage, Jens P.

    1994-01-01

    A set of concurrent processes communicating through shared variables is an often used model for hardware systems. This paper presents three modeling techniques for representing such shared variables in VHDL, depending on the acceptable constraints on accesses to the variables. Also a set...... of guidelines for handling atomic updates of multiple shared variables is given. 1 Introduction It is often desirable to partition a computational system into discrete functional units which cooperates to....

  5. Upscaling of greenhouse gas emissions in upland forestry following clearfell

    Science.gov (United States)

    Toet, Sylvia; Keane, Ben; Yamulki, Sirwan; Blei, Emanuel; Gibson-Poole, Simon; Xenakis, Georgios; Perks, Mike; Morison, James; Ineson, Phil

    2016-04-01

    Data on greenhouse gas (GHG) emissions caused by forest management activities are limited. Management such as clearfelling may, however, have major impacts on the GHG balance of forests through effects of soil disturbance, increased water table, and brash and root inputs. Besides carbon dioxide (CO2), the biogenic GHGs nitrous oxide (N2O) and methane (CH4) may also contribute to GHG emissions from managed forests. Accurate flux estimates of all three GHGs are therefore necessary, but, since GHG emissions usually show large spatial and temporal variability, in particular CH4 and N2O fluxes, high-frequency GHG flux measurements and better understanding of their controls are central to improve process-based flux models and GHG budgets at multiple scales. In this study, we determined CO2, CH4 and N2O emissions following felling in a mature Sitka spruce (Picea sitchensis) stand in an upland forest in northern England. High-frequency measurements were made along a transect using a novel, automated GHG chamber flux system ('SkyLine') developed at the University of York. The replicated, linear experiment aimed (1) to quantify GHG emissions from three main topographical features at the clearfell site, i.e. the ridges on which trees had been planted, the hollows in between and the drainage ditches, and (2) to determine the effects of the green-needle component of the discarded brash. We also measured abiotic soil and climatic factors alongside the 'SkyLine' GHG flux measurements to identify drivers of the observed GHG emissions. All three topographic features were overall sources of GHG emissions (in CO2 equivalents), and, although drainage ditches are often not included in studies, GHG emissions per unit area were highest from ditches, followed by ridges and lowest in hollows. The CO2 emissions were most important in the GHG balance of ridges and hollows, but CH4 emissions were very high from the drainage ditches, contributing to over 50% of their overall net GHG emissions

  6. Assessment of nitrous oxide and methane emissions for California agriculture

    Science.gov (United States)

    Horwath, W. R.; Burger, M.; Assa, Y.; Wilson, T. J.

    2012-12-01

    The California Global Warming Solutions Act of 2006 (AB 32) mandates comprehensive strategies to reduce nitrous oxide (N2O) and methane (CH4) emissions. In agriculture crop production, sources of N2O are related to nitrogen fertilization while CH4 emission is associated with rice production. More than half the GHG emissions from agriculture are attributed to N2O production. Currently, baseline N2O emission data for most cropping systems in the State is lacking. Estimates of CH4 emission in rice have been established from previous studies, but a lack of information exists for its expansion into the San Joaquin Delta to address subsidence issues. The paucity of N2O emission data has hampered biogeochemical modeling efforts. The objectives of this assessment are to (1) measure annual N2O and CH4 emissions for major California crops (vineyards, almonds, tomato, wheat, alfalfa, lettuce, and rice) under typical management practices, (2) characterize the effects of environmental factors on the temporal profile of N2O and CH4 emissions, and (3) determine N2O emission factors. The growth of rice in Delta peat soils produced highly variable CH4 emissions depending on tillage intensity. In 2010, standard tillage produced 184 kg CH4-C/ha while in 2011 after deep plowing placing rice residue deeper into the soil, only 26 kg CH4-C/ha was observed. In processing tomato systems, an average 2.5 kg N2O-N/ha was emitted with standard fertilization (160 kg N / ha), similar to background emissions and those from a drip irrigated system, while 4.0 to 5.8 kg N2O-N /ha y-1 was emitted at fertilizer rates of 225 and 300 kg N /ha (see Fig. 1 for example of temporal sources of emissions). About half the annual emissions were emitted within 3 d after the first seasonal rainfall event. In other tomato studies, estimated losses of fertilizer N as N2O were 0.38 ± 0.03 kg/ha y-1 in a drip irrigated system and 1.79 ± 0.21 kg/ha y-1 in furrow irrigated system, which was equivalent to 0.19% and 0

  7. Fugitive particulate emission factors for dry fly ash disposal.

    Science.gov (United States)

    Mueller, Stephen F; Mallard, Jonathan W; Mao, Qi; Shaw, Stephanie L

    2013-07-01

    fly ash emission factors (EFs) derived by this study contribute to the small existing knowledge base for a type of pollutant that will become increasingly important as ambient particulate standards become tighter. In areas that are not in attainment with standards, realistic EFs can be used for compliance modeling and can help identify which classes of sources are best targeted to achieve desired air quality levels. In addition, understanding the natural variability in fugitive fly ash emissions can suggest methods that are most likely to be successful in controlling fugitive emissions related to dry fly ash storage.

  8. Photosynthesis and isoprene emission from trees along an urban-rural gradient in Texas.

    Science.gov (United States)

    Lahr, Eleanor C; Schade, Gunnar W; Crossett, Caitlin C; Watson, Matthew R

    2015-11-01

    Isoprene emission is an important mechanism for improving the thermotolerance of plant photosystems as temperatures increase. In this study, we measured photosynthesis and isoprene emission in trees along an urban-rural gradient that serves as a proxy for climate change, to understand daily and seasonal responses to changes in temperature and other environmental variables. Leaf-level gas exchange and basal isoprene emission of post oak (Quercus stellata) and sweet gum (Liquidambar styraciflua) were recorded at regular intervals over an entire growing season at urban, suburban, and rural sites in eastern Texas. In addition, the temperature and atmospheric carbon dioxide concentration experienced by leaves were experimentally manipulated in spring, early summer, and late summer. We found that trees experienced lower stomatal conductance and photosynthesis and higher isoprene emission, at the urban and suburban sites compared to the rural site. Path analysis indicated a daily positive effect of isoprene emission on photosynthesis, but unexpectedly, higher isoprene emission from urban trees was not associated with improved photosynthesis as temperatures increased during the growing season. Furthermore, urban trees experienced relatively higher isoprene emission at high CO2 concentrations, while isoprene emission was suppressed at the other sites. These results suggest that isoprene emission may be less beneficial in urban, and potentially future, environmental conditions, particularly if higher temperatures override the suppressive effects of high CO2 on isoprene emission. These are important considerations for modeling future biosphere-atmosphere interactions and for understanding tree physiological responses to climate change. © 2015 John Wiley & Sons Ltd.

  9. An empirical model to predict road dust emissions based on pavement and traffic characteristics.

    Science.gov (United States)

    Padoan, Elio; Ajmone-Marsan, Franco; Querol, Xavier; Amato, Fulvio

    2017-11-08

    The relative impact of non-exhaust sources (i.e. road dust, tire wear, road wear and brake wear particles) on urban air quality is increasing. Among them, road dust resuspension has generally the highest impact on PM concentrations but its spatio-temporal variability has been rarely studied and modeled. Some recent studies attempted to observe and describe the time-variability but, as it is driven by traffic and meteorology, uncertainty remains on the seasonality of emissions. The knowledge gap on spatial variability is much wider, as several factors have been pointed out as responsible for road dust build-up: pavement characteristics, traffic intensity and speed, fleet composition, proximity to traffic lights, but also the presence of external sources. However, no parameterization is available as a function of these variables. We investigated mobile road dust smaller than 10 μm (MF10) in two cities with different climatic and traffic conditions (Barcelona and Turin), to explore MF10 seasonal variability and the relationship between MF10 and site characteristics (pavement macrotexture, traffic intensity and proximity to braking zone). Moreover, we provide the first estimates of emission factors in the Po Valley both in summer and winter conditions. Our results showed a good inverse relationship between MF10 and macro-texture, traffic intensity and distance from the nearest braking zone. We also found a clear seasonal effect of road dust emissions, with higher emission in summer, likely due to the lower pavement moisture. These results allowed building a simple empirical mode, predicting maximal dust loadings and, consequently, emission potential, based on the aforementioned data. This model will need to be scaled for meteorological effect, using methods accounting for weather and pavement moisture. This can significantly improve bottom-up emission inventory for spatial allocation of emissions and air quality management, to select those roads with higher emissions

  10. Acoustic and optical emission during laser-induced plasma formation

    Energy Technology Data Exchange (ETDEWEB)

    Conesa, S.; Palanco, S.; Laserna, J.J. E-mail: laserna@uma.es

    2004-09-20

    Laser ablation is widely used in laser processing and analysis of materials. The laser beam evaporates and ionizes material, creating a plasma plume that expands to variable extent and morphology depending on both the sample and its surrounding gas properties. At ambient pressure a shock wave front appears, traveling at variable velocities which are related to the own plasma formation mechanism. Plasma images as well as the acoustic spectral content of the emission within the aural perception range are related to the plasma formation and evolution dynamics. These results are discussed on the basis of different plasma expansion mechanisms.

  11. Strong Decomposition of Random Variables

    DEFF Research Database (Denmark)

    Hoffmann-Jørgensen, Jørgen; Kagan, Abram M.; Pitt, Loren D.

    2007-01-01

    A random variable X is stongly decomposable if X=Y+Z where Y=Φ(X) and Z=X-Φ(X) are independent non-degenerated random variables (called the components). It is shown that at least one of the components is singular, and we derive a necessary and sufficient condition for strong decomposability...... of a discrete random variable....

  12. THE VARIABILITY OF INTERLANGUAGE USE

    African Journals Online (AJOL)

    www

    This pattern of linguistic behaviour is called "non-systematic variability". In this article, the phenomenon of this variability in L2 knowledge is investigated. The existing body of knowledge about L2 acquisition provides ample proof that L2 learners are characteristically variable in their interlanguage use. The question arises ...

  13. Preservice Teachers' Understanding of Variable

    Science.gov (United States)

    Brown, Sue; Bergman, Judy

    2013-01-01

    This study examines the research on middle school students' understanding of variables and explores preservice elementary and middle school teachers' knowledge of variables. According to research studies, middle school students have limited understanding of variables. Many studies have examined the performance of middle school students and offered…

  14. The Emissions Gap Report 2015

    DEFF Research Database (Denmark)

    Following the historic signing of the 2030 Agenda for Sustainable Development, this sixth edition of the UNEP Emissions Gap Report comes as world leaders start gathering in Paris to establish a new agreement on climate change. The report offers an independent assessment of the mitigation...... contributions from the Intended Nationally Determined Contributions (INDC) committed to by 1 October 2015, by the 146 countries that account for around 90 per cent of global emissions. It compares the 2030 emission levels that would result from these commitments with what science tells us would keep average...

  15. Livestock and greenhouse gas emissions

    DEFF Research Database (Denmark)

    Herrero, M; Gerber, P; Vellinga, T

    2011-01-01

    emissions. In reality, estimates of international scientific organizations such as the International Governmental Panel on Climate Change (IPCC) and the Food and Agriculture Organization (FAO) are in close agreement, with variation mainly arising on how GHG emissions are allocated to land use and land use...... change. Other estimates involve major deviations from international protocols, such as estimated global warming potential of CH4 or including respired CO2 in GHG emissions. These approaches also fail to differentiate short-term CO2 arising from oxidation of plant C by ruminants from CO2 released from...

  16. Jovian X-ray emissions

    Science.gov (United States)

    Waite, J. H.; Lewis, W. S.; Gladstone, G. R.; Fabian, A. C.; Brandt, W. N.

    1996-01-01

    The Einstein and Rosat observations of X-ray emissions from Jupiter are summarized. Jupiter's soft X-ray emission is observed to originate from the planet's auroral zones, and specifically, from its equatorial region. The processes responsible for these emissions are not established. The brightness distribution of the Jovian X-rays is characterized by the dependence on central meridian longitude and by north-south and morning-afternoon asymmetries. The X-rays observed during the impact of the comet Shoemaker-Levy 9 are believed to be impact-induced brightenings of the X-ray aurora.

  17. Greenhouse Gas Emissions: Quantifying Methane Emissions from Livestock

    OpenAIRE

    Rafiu O. Yusuf; Zainura Z. Noor; Ahmad H. Abba; Mohd Ariffin Abu Hassan; Mohd Fadhil Mohd Din

    2012-01-01

    Problem statement: The rearing of animals for domestic consumption and export invariably lead to the production of methane as a product of digestion. This study investigated the emission of methane from Malaysian livestock between 1980 and 2008. Approach: Seven categories of animals identified were camel, buffalo, sheep, goats, horse, pigs and poultry. The estimation of methane was based on the IPCC Tier 1 and Tier 2 methods. Methane emission from cattle rose by 44% within the period from 45....

  18. Thermal Emission from Structured Media

    Science.gov (United States)

    Zimmerman, Ian Andrew

    This dissertation covers a study of the use of macroscopic structure as a means of controlling thermal emission in the THz and mid-IR frequency regions. Chapter 1 presents a brief introduction to the THz frequency region and to the concept of the photonic crystal, the primary type of geometry used. Chapter 2 compares the two most common methods used to calculate the thermal emission of a structure whose components are all at the same temperature. These methods are compared in terms of the results they give and in terms of how computationally involved the methods are. The first method explored involves using Kirchhoff's law of thermal emission which equates the absorptivity and emissivity of a structure. The second method is to calculate the emission directly from the Green's function using the microscopic thermal currents given by the Fluctuation-Dissipation theorem. A derivation of the second method is given, and the equality between the two methods is proven in 1D. It is shown that the Kirchhoff's law method is much more computationally efficient, and it is therefore used for the parametric studies of the structures which make up the remainder of this document. Chapter 3 covers work done in the THz regime. In the THz frequency regime, where a historic lack of sources has in part impeded full exploration and utilization, a photonic crystal design is proposed to control the thermal emission. It is shown that using a 1D bi-layered photonic crystal, composed of alternating section of silicon wafers and vacuum sections, it is possible to tailor many narrowband emission features over a broadband frequency range. In simulation both spectral and directional thermal emission control is demonstrated, and a parametric study is performed to explore how changes in the geometry of the photonic crystal change its thermal emission signature. A description is then given of how the photonic crystal is constructed and how its thermal emission is measured using Fourier transform

  19. Integration i flere variable

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    2010-01-01

    Denne note handler om parameterfremstillinger for kurver, flader og rumlige områder og om integration af funktioner på sådanne geometriske objekter. Formålet er primært at opstille og motivere de generelle definitioner og beregninger af henholdsvis kurve- \\, flade- \\, og rum-integraler. Udgangspu......Denne note handler om parameterfremstillinger for kurver, flader og rumlige områder og om integration af funktioner på sådanne geometriske objekter. Formålet er primært at opstille og motivere de generelle definitioner og beregninger af henholdsvis kurve- \\, flade- \\, og rum......-integralerne. Undervejs introduceres \\texttt{Integrator8}. Det er en pakke med Maple procedurer, som er udviklet specielt med henblik på eksempelbaseret visuel læring af de indledende integrationsbegreber og deres mangfoldige anvendelser. Vi giver eksempler på, hvordan integration i flere variable anvendes til beregning...... og forståelse af rumfang, vægt, massemidtpunkter, inertimomenter, kraftmomenter, etc. Flowkurverne for et givet vektorfelt i rummet kan findes og visualiseres med \\texttt{Integrator8}. De vigtige begreber divergens og rotation for et vektorfelt fremtræder derved som naturlige størrelser til...

  20. Variables moderadoras del estres

    Directory of Open Access Journals (Sweden)

    María Cristina Richaud de Minzi

    1999-01-01

    Full Text Available El objetivo del presente trabajo es analizar la influenciadel estilo atribucional, la confianza interpersonal y el soporte social sobre la percepción de la amenaza. Se administraron la Escala de Estilo Atribucional; la Manheim Interview 01 Social Support, la Escala de Confianza Interpersonal; y el Inventario de Situaciones y Respuestas de Ansiedad, a 260 sujetos de ambos sexos, de 30 años de edad promedio, de nivel socioeconómico medio, residentes en la ciudad de Buenos Aires. El soporte social no demostró influencia significativa sobre la percepción de la amenaza. Con respecto a la influencia del estilo atribucional se puede decir que las personas indefensas perciben más amenaza, especialmente expresada como ansiedad cognitiva y, en menor grado, como ansiedad motora o conductual. La confianza interpersonal demostró ser una variable importante en la percepción de la amenaza. Los sujetos que presentaron alta desconfianza hacia las personas de su entorno perciben un mundo amenazante, que se manifiesta como ansiedad cognitiva, fisiológica y motora o conductual.

  1. Hydrostatic continuously variable transmission

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, T.; Saito, M.; Matsuto, T.; Nakajima, Y.; Sakakibara, K.; Yakigaya, N.; Nakamura, K.

    1989-05-09

    A hydrostatic continuously variable transmission is described, comprising: a swashplate type hydraulic pump having a pump swashplate and annularly arranged pump plungers whose suction and discharge strokes are provided by the pump swashplate; a swashplate type hydraulic motor having a motor swashplate and annularly arranged motor plungers whose expansion and shrinkage strokes are provided by the motor swashplate; and a hydraulic closed circuit formed between the hydraulic pump and the hydraulic motor. The transmission has at least one of a relationship that a middle point of a discharge region of the hydraulic pump is angularly delayed at a given angle in a direction of rotation of the hydraulic pump relative to a tilting axis of the pump swashplate and a relationship that a middle point of an expansion region of the hydraulic motor is angularly advanced at a given angle in a direction of rotation of the hydraulic motor relative to a tilting axis of the motor swashplate, wherein the transmission has at least one of a relationship that a suction region of the hydraulic pump is set at an angle larger than that of the discharge region thereof and a relationship that a shrinkage region of the hydraulic motor is set at an angle larger than that of the expansion region of the motor.

  2. Variable subsistence indemnity

    CERN Document Server

    1999-01-01

    At its meeting on 9 December 1998, the Finance Committee approved, with effect from 1st January 1999, adjustments to the Variable Subsistence Indemnity according to the rates published by the United Nations Organization given in document CERN/FC/4113. This decision maintained the reference method in force since 1983. The Management now proposes to adjust the CERN rates of indemnities, with effect from 1st January 2000, on the basis of the United Nations 1999 rates, as shown for typical destinations in the table contained in this document. Although a precise estimate of the cost effect for duty travel is difficult to achieve due to currency exchange values, it is probable that this will remain unchanged if calculated in Swiss francs. The Management also proposes to formalise the practice of paying a lower subsistence indemnity than the approved basic amount, wherever feasible for events such as group duty travel to conferences or similar events, as discussed at the Finance Committee in December 1998. An amendm...

  3. Variable angle correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Kyo [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with 13C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.

  4. River plastic emissions to the world's oceans

    Science.gov (United States)

    Lebreton, Laurent C. M.; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia

    2017-06-01

    Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.

  5. Zero emission city. Preliminary study; Null-Emissions-Stadt. Sondierungsstudie

    Energy Technology Data Exchange (ETDEWEB)

    Diefenbach, N.; Enseling, A.; Werner, P.; Flade, A.; Greiff, R.; Hennings, D.; Muehlich, E.; Wullkopf, U.; Sturm, P.; Kieslich, W.; Born, R.; Grossklos, M.; Hatteh, R.; Mueller, K.; Ratschow, A.; Valouch-Fornoff, C.

    2002-10-01

    The idea of a 'zero emission city' is investigated by the Institut Wohnen und Umwelt on behalf of the Federal Minister of Education and Research. After describing the current situation and defining the key parameters of a 'zero emission city', settlement structures, power supply, production processes and transportation are analyzed and linked with the communal action level to obtain a framework for research, activities and actions. The study ends with recommendations for a research programme 'zero emission city'. (orig.) [German] Die von den Staedten der Industrielaender ausgehenden Emissionen stellen im Hinblick auf die globalen Belastungen wie z.B. Treibhauseffekt, Ozonabbau und Versauerung das Hauptproblem dar. Aus diesem Grunde bietet es sich an, den Gedanken der 'Null-Emissions-Stadt', der Vision einer moeglichst emissionsfreien Stadt, aufzugreifen und auf seine Tragfaehigkeit fuer innovative Handlungsmodelle forschungsstrategisch zu ueberpruefen. Das Bundesministerium fuer Bildung und Forschung hat das Institut Wohnen und Umwelt beauftragt, in einer Sondierungsstudie dieser Fragestellung nachzugehen. Nach der Festlegung der Ausgangsbedingungen und Eckpunkte der Vision 'Null-Emissions-Stadt' und der Analyse der vier Handlungsfelder Siedlungsstrukturen, Energieversorgung, Produktionsprozesse (Kreislaufwirtschaft) und Verkehr werden diese aufgegriffen und mit der kommunalen Handlungsebene verknuepft und zu einem Forschungs-, Handlungs- und moeglichen Aktionsrahmen zusammengefuegt. Die Studie schliesst mit Hinweisen fuer die Gestaltung eines Forschungsprogramms 'Null-Emissions-Stadt'. (orig.)

  6. Environmental Controls on Wildfire Emission Factors in Alaska during the Summer of 2015

    Science.gov (United States)

    Wiggins, E. B.

    2016-12-01

    Boreal forests contain significant reservoirs of organic carbon and are subject to severe wildfires. Boreal fire emissions are important to quantify with respect to climate and ecosystem dynamics, especially within the rapidly changing climate of the Northern Hemisphere. The amount and composition of emissions from fires is highly variable and dependent on environmental conditions such as local weather, soil moisture, and land cover type. Emission factors are regularly used to estimate the composition of fire emissions. We investigated environmental controls on boreal forest fire emission factors in Alaska during the summer of 2015. A high-resolution fire emissions inventory was combined with an atmospheric transport model to estimate fire contribution to trace gas variability at an in-situ observational tower. Periods of high fire influence at the tower were identified, and emission ratios for CO, CO2, and CH4 were calculated for these times. Individual fire contributions to the trace gas signals observed at the tower were isolated utilizing the fire emissions inventory combined with an atmospheric transport model. Environmental conditions including soil moisture, meteorology, land and tree cover, fire type (smoldering vs. flaming), and burn severity were associated with individual fires that contributed to the trace gas signal at the tower. We found that soil moisture derived from the SMAP (Soil Moisture Active Passive) satellite was correlated with burned area and that local daily meteorological variables, including vapor pressure deficit and temperature, explained some of the variance in emission factors. The results from this study may enable improved estimates of boreal fire emissions during a period of rapidly changing environmental conditions.

  7. Monthly and spatially resolved black carbon emission inventory of India: uncertainty analysis

    Directory of Open Access Journals (Sweden)

    U. Paliwal

    2016-10-01

    Full Text Available Black carbon (BC emissions from India for the year 2011 are estimated to be 901.11 ± 151.56 Gg yr−1 based on a new ground-up, GIS-based inventory. The grid-based, spatially resolved emission inventory includes, in addition to conventional sources, emissions from kerosene lamps, forest fires, diesel-powered irrigation pumps and electricity generators at mobile towers. The emissions have been estimated at district level and were spatially distributed onto grids at a resolution of 40 × 40 km2. The uncertainty in emissions has been estimated using a Monte Carlo simulation by considering the variability in activity data and emission factors. Monthly variation of BC emissions has also been estimated to account for the seasonal variability. To the total BC emissions, domestic fuels contributed most significantly (47 %, followed by industry (22 %, transport (17 %, open burning (12 % and others (2 %. The spatial and seasonal resolution of the inventory will be useful for modeling BC transport in the atmosphere for air quality, global warming and other process-level studies that require greater temporal resolution than traditional inventories.

  8. Life cycle Greenhouse gas emissions of current Oil Sands Technologies: surface mining and in situ applications.

    Science.gov (United States)

    Bergerson, Joule A; Kofoworola, Oyeshola; Charpentier, Alex D; Sleep, Sylvia; Maclean, Heather L

    2012-07-17

    Life cycle greenhouse gas (GHG) emissions associated with two major recovery and extraction processes currently utilized in Alberta's oil sands, surface mining and in situ, are quantified. Process modules are developed and integrated into a life cycle model-GHOST (GreenHouse gas emissions of current Oil Sands Technologies) developed in prior work. Recovery and extraction of bitumen through surface mining and in situ processes result in 3-9 and 9-16 g CO(2)eq/MJ bitumen, respectively; upgrading emissions are an additional 6-17 g CO(2)eq/MJ synthetic crude oil (SCO) (all results are on a HHV basis). Although a high degree of variability exists in well-to-wheel emissions due to differences in technologies employed, operating conditions, and product characteristics, the surface mining dilbit and the in situ SCO pathways have the lowest and highest emissions, 88 and 120 g CO(2)eq/MJ reformulated gasoline. Through the use of improved data obtained from operating oil sands projects, we present ranges of emissions that overlap with emissions in literature for conventional crude oil. An increased focus is recommended in policy discussions on understanding interproject variability of emissions of both oil sands and conventional crudes, as this has not been adequately represented in previous studies.

  9. Danish emission inventory for particular matter (PM)

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.; Winther, M.; Illerup, J.B.; Hjort Mikkelsen, M.

    2003-11-01

    The first Danish emission inventory that was reported in 2002 was a provisional-estimate based on data presently available. This report documents methodology, emission factors and references used for an improved Danish emission inventory for particulate matter. Further results of the improved emission inventory for the year 2000 are shown. The particulate matter emission inventory includes TSP, PM,, and PM, The report covers emission inventories for transport and stationary combustion. An appendix covering emissions from agriculture is also included. For the transport sector, both exhaust and non-exhaust emission such as tyre and break wear and road abrasion are included. (au)

  10. Real-world emissions of in-use off-road vehicles in Mexico.

    Science.gov (United States)

    Zavala, Miguel; Huertas, Jose Ignacio; Prato, Daniel; Jazcilevich, Aron; Aguilar, Andrés; Balam, Marco; Misra, Chandan; Molina, Luisa T

    2017-09-01

    Off-road vehicles used in construction and agricultural activities can contribute substantially to emissions of gaseous pollutants and can be a major source of submicrometer carbonaceous particles in many parts of the world. However, there have been relatively few efforts in quantifying the emission factors (EFs) and for estimating the potential emission reduction benefits using emission control technologies for these vehicles. This study characterized the black carbon (BC) component of particulate matter and NOx, CO, and CO2 EFs of selected diesel-powered off-road mobile sources in Mexico under real-world operating conditions using on-board portable emissions measurements systems (PEMS). The vehicles sampled included two backhoes, one tractor, a crane, an excavator, two front loaders, two bulldozers, an air compressor, and a power generator used in the construction and agricultural activities. For a selected number of these vehicles the emissions were further characterized with wall-flow diesel particle filters (DPFs) and partial-flow DPFs (p-DPFs) installed. Fuel-based EFs presented less variability than time-based emission rates, particularly for the BC. Average baseline EFs in working conditions for BC, NOx, and CO ranged from 0.04 to 5.7, from 12.6 to 81.8, and from 7.9 to 285.7 g/kg-fuel, respectively, and a high dependency by operation mode and by vehicle type was observed. Measurement-base frequency distributions of EFs by operation mode are proposed as an alternative method for characterizing the variability of off-road vehicles emissions under real-world conditions. Mass-based reductions for black carbon EFs were substantially large (above 99%) when DPFs were installed and the vehicles were idling, and the reductions were moderate (in the 20-60% range) for p-DPFs in working operating conditions. The observed high variability in measured EFs also indicates the need for detailed vehicle operation data for accurately estimating emissions from off

  11. Statistical analysis of the operating parameters which affect cupola emissions

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.W.; Draper, A.B.

    1977-12-01

    A sampling program was undertaken to determine the operating parameters which affected air pollution emission from gray iron foundry cupolas. The experimental design utilized the analysis of variance routine. Four independent variables were selected for examination on the basis of previous work reported in the literature. These were: (1) blast rate; (2) iron-coke ratio; (3) blast temperature; and (4) cupola size. The last variable was chosen since it most directly affects melt rate. Emissions from cupolas for which concern has been expressed are particle matter and carbon monoxide. The dependent variables were, therefore, particle loading, particle size distribution, and carbon monoxide concentration. Seven production foundries were visited and samples taken under conditions prescribed by the experimental plan. The data obtained from these tests were analyzed using the analysis of variance and other statistical techniques where applicable. The results indicated that blast rate, blast temperature, and cupola size affected particle emissions and the latter two also affected the particle size distribution. The particle size information was also unique in that it showed a consistent particle size distribution at all seven foundaries with a sizable fraction of the particles less than 1.0 micrometers in diameter.

  12. Adoption of Emissions Abating Technologies by U.S. Electricity Producing Firms Under the SO2 Emission Allowance Market

    Science.gov (United States)

    Creamer, Gregorio Bernardo

    should be equal to the product generated by using it and to the activities that are required by new regulations. The comparative technological and scale efficiency factors of coal-based electricity producing plants are calculated using the Data Envelopment Analysis (DEA) framework, and used as proxies to test this condition. In the empirical analysis, econometric models of the response of firms to emissions control are analyzed around the following aspects: (1) characterization of the behavior of firms and their efficiency, (2) relevant variables that trigger the adoption of technology, that is, the acquisition of scrubbers , and (3) the influence of exogenous variables, such as the existence of contracts, distance from mine to plant, and local conditions of the region where plants are located.

  13. Global Emissions of Terpenoid VOCs from Terrestrial Vegetation in the Last Millennium

    Energy Technology Data Exchange (ETDEWEB)

    Acosta Navarro, J. C.; Smolander, S.; Struthers, H.; Zorita, E.; Ekman, A. M.; Kaplan, J. O.; Guenther, Alex B.; Arneth, A.; Riipinen, I.

    2014-06-16

    We investigated the millennial variability of global BVOC emissions by using two independent numerical models: The Model of Emissions of Gases and Aerosols from Nature (MEGAN), for isoprene, monoterpene and sesquiterpene and Lund-Potsdam-Jena General Ecosystem Simulator (LPJ8 GUESS), for isoprene and monoterpenes. We found the millennial trends of global isoprene emissions to be mostly affected by land cover and atmospheric carbon dioxide changes, whereas monoterpene and sesquiterpene emission were dominated by temperature change. Isoprene emissions declined substantially in regions with large and rapid land cover change. In addition, isoprene emission sensitivity to drought proved to have signicant short term global effects. By the end of the past millennium MEGAN isoprene emissions were 634 TgC yr-1 (13% and 19% less than during during 1750-1850 and 1000- 15 1200, respectively) and LPJ-GUESS emissions were 323 TgC yr-1 (15% and 20% less than during 1750-1850 and 1000-1200, respectively). Monoterpene emissions were 89 TgC yr-1 (10% and 6% higher than during 1750-1850 and 1000-1200, respectively) in MEGAN, and 24 TgC yr-1 (2% higher and 5% 19 20 less than during 1750-1850 and 1000-1200, respectively) in LPJ-GUESS. MEGAN sesquiterpene emissions were 36 TgC yr-1 (10% and 4% higher than during1750-1850 and 1000-1200, respectively). Although both models capture similar We investigated the millennial variability of global BVOC emissions by using two independent numerical models: The Model of Emissions of Gases and Aerosols from Nature (MEGAN), for isoprene, monoterpene and sesquiterpene and Lund-Potsdam-Jena General Ecosystem Simulator (LPJ8GUESS), for isoprene and monoterpenes. We found the millennial trends ofglobal isoprene emissions to be mostly a*ected by land cover and atmospheric carbon dioxide changes, whereas monoterpene and sesquiterpene emission were dominated by temperature change. Isoprene emissions declined substantially in regions with large and rapid

  14. Controlling radiated emissions by design

    CERN Document Server

    Mardiguian, Michel

    2014-01-01

    The 3rd edition of Controlling Radiated Emissions by Design has been updated to reflect the latest changes in the field. New to this edition is material related to technical advances, specifically super-fast data rates on wire pairs, with no increase in RF interference. Throughout the book, details are given to control RF emissions using EMC design techniques. This book retains the step-by-step approach for incorporating EMC into every new design from the ground up. It describes the selection of quieter IC technologies, their implementation into a noise-free printed circuit layout, and the gathering of these into a low emissions package. Also included is how to design an I/O filter, along with connectors and cable considerations. All guidelines are supported throughout with comprehensive calculated examples. Design engineers, EMC specialists, and technicians will benefit from learning about the development of more efficient and economical control of emissions.

  15. Mercury Emissions: The Global Context

    Science.gov (United States)

    Mercury emissions are a global problem that knows no national or continental boundaries. Mercury that is emitted to the air can travel thousands of miles in the atmosphere before it is eventually deposited back to the earth.

  16. Advanced Emissions Control Development Program

    Energy Technology Data Exchange (ETDEWEB)

    A.P.Evans; K.E. Redinger; M.J. Holmes

    1998-04-01

    The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).

  17. Dataset of NRDA emission data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Emissions data from open air oil burns. This dataset is associated with the following publication: Gullett, B., J. Aurell, A. Holder, B. Mitchell, D. Greenwell, M....

  18. Turkey Run Landfill Emissions Dataset

    Data.gov (United States)

    U.S. Environmental Protection Agency — landfill emissions measurements for the Turkey run landfill in Georgia. This dataset is associated with the following publication: De la Cruz, F., R. Green, G....

  19. Intraspecific chromosome variability

    Directory of Open Access Journals (Sweden)

    N Dubinin

    2010-12-01

    Full Text Available (Editorial preface. The publication is presented in order to remind us of one of dramatic pages of the history of genetics. It re-opens for the contemporary reader a comprehensive work marking the priority change from plant cytogenetics to animal cytogenetics led by wide population studies which were conducted on Drosophila polytene chromosomes. The year of the publication (1937 became the point of irretrievable branching between the directions of Old World and New World genetics connected with the problems of chromosome variability and its significance for the evolution of the species. The famous book of T. Dobzhansky (1937 was published by Columbia University in the US under the title “Genetics and the origin of species”, and in the shadow of this American ‘skybuilding’ all other works grew dim. It is remarkable that both Dobzhansky and Dubinin come to similar conclusions about the role of chromosomes in speciation. This is not surprising given that they both might be considered as representatives of the Russian genetic school, by their birth and education. Interestingly, Dobzhansky had never referred to the full paper of Dubinin et al. (1937, though a previous short communication in Nature (1936 was included together with all former papers on the related subject. In full, the volume of the original publication printed in the Biological Journal in Moscow comprised 47 pages, in that number 41 pages of the Russian text accompanied by 16 Figs, a table and reference list, and, above all, 6 pages of the English summary. This final part in English is now reproduced in the authors’ version with the only addition being the reference list in the originally printed form.

  20. Reconciling divergent estimates of oil and gas methane emissions.

    Science.gov (United States)

    Zavala-Araiza, Daniel; Lyon, David R; Alvarez, Ramón A; Davis, Kenneth J; Harriss, Robert; Herndon, Scott C; Karion, Anna; Kort, Eric Adam; Lamb, Brian K; Lan, Xin; Marchese, Anthony J; Pacala, Stephen W; Robinson, Allen L; Shepson, Paul B; Sweeney, Colm; Talbot, Robert; Townsend-Small, Amy; Yacovitch, Tara I; Zimmerle, Daniel J; Hamburg, Steven P

    2015-12-22

    Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency's Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%.

  1. Baselining Fugitive and Vented Emissions Across Canadian Energy Developments

    Science.gov (United States)

    O'Connell, L.; Risk, D. A.; Fougère, C. R.; Lavoie, M.; Atherton, E. E.; Baillie, J.; MacKay, K.; Marshall, A. D.

    2016-12-01

    A recent trilateral accord between North American governments pledges to cut energy sector methane emissions 40-45 per cent below 2012 levels by 2025. Effective methane-reduction policy relies on accurate and spatially extensive emissions data. In this study, we assessed the feasibility of bottom-up data collection for Canadian energy developments, using vehicle-based emission screening and volumetric measurement, combined with forward looking infrared (FLIR) detection for pinpointing source. We analyzed trends across many Canadian developments using an 80,000 km survey campaign conducted in 2015-16 in which CO2, CH4, H2S, and δ13CH4 were measured in proximity to over ten thousand well pads. We found that emissions varied according to infrastructure age, operator size, product, and extraction style. Using these data, we conducted an analysis across several variables to evaluate the potential success of non-exhaustive campaigns for capturing trends, and super-emitters, across the Canadian industry. We found that campaigns would be fiscally feasible, and could be statistically significant depending on scale. However, success was very sensitive to the degree of variation amongst operators and developments, for which we suggest a Monte-Carlo type optimization approach that balances survey coverage with attention to specific localized threats. Similar analyses should be conducted in other accord countries because effective and harmonized oversight could help accelerate emissions reductions.

  2. On organic emissions testing from indoor consumer products' use.

    Science.gov (United States)

    Bartzis, J; Wolkoff, P; Stranger, M; Efthimiou, G; Tolis, E I; Maes, F; Nørgaard, A W; Ventura, G; Kalimeri, K K; Goelen, E; Fernandes, O

    2015-03-21

    A wide range of consumer and personal care products may, during their use, release significant amounts of volatile organic compounds (VOC) into the air. The identification and quantification of the emissions from such sources is typically performed in emission test chambers. A major question is to what degree the obtained emissions are reproducible and directly applicable to real situations. The present work attempts partly to address this question by comparison of selected VOC emissions in specific consumer products tested in chambers of various dimensions. The measurements were performed in three test chambers of different volumes (0.26-20 m(3)). The analytic performance of the laboratories was rigorously assessed prior to chamber testing. The results show emission variation for major VOC (terpenes); however, it remains in general, within the same order of magnitude for all tests. This variability does not seem to correlate with the chamber volume. It rather depends on the overall testing conditions. The present work is undertaken in the frame of EPHECT European Project. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Estimating emissions from railway traffic

    Energy Technology Data Exchange (ETDEWEB)

    Joergensen, M.W.; Sorenson, C.

    1997-07-01

    The report discusses methods that can be used to estimate the emissions from various kinds of railway traffic. The methods are based on the estimation of the energy consumption of the train, so that comparisons can be made between electric and diesel driven trains. Typical values are given for the necessary traffic parameters, emission factors, and train loading. Detailed models for train energy consumption are presented, as well as empirically based methods using average train speed and distance between stop. (au)

  4. Simulating industrial emissions using atmospheric dispersion modeling system: model performance and source emission factors.

    Science.gov (United States)

    El-Fadel, M; Abi-Esber, L

    2012-03-01

    In this paper, the Gaussian Atmospheric Dispersion Modeling System (ADMS4) was coupled with field observations of surface meteorology and concentrations of several air quality indicators (nitrogen oxides (NOx), carbon monoxide (CO), fine particulate matter (PM10) and sulfur dioxide (SO2)) to test the applicability of source emission factors set by the European Environment Agency (EEA) and the United States Environmental Protection Agency (USEPA) at an industrial complex. Best emission factors and data groupings based on receptor location, type of terrain and wind speed, were relied upon to examine model performance using statistical analyses of simulated and observed data. The model performance was deemed satisfactory for several scenarios when receptors were located at downwind sites with index of agreement 'd' values reaching 0.58, fractional bias 'FB' and geometric mean bias 'MG' values approaching 0 and 1, respectively, and normalized mean square error 'NMSE' values as low as 2.17. However, median ratios of predicted to observed concentrations 'Cp/Co' at variable downstream distances were 0.01, 0.36, 0.76 and 0.19 for NOx, CO, PM10 and SO2, respectively, and the fraction of predictions within a factor of two of observations 'FAC2' values were lower than 0.5, indicating that the model could not adequately replicate all observed variations in emittant concentrations. Also, the model was found to be significantly sensitive to the input emission factor bringing into light the deficiency in regulatory compliance modeling which often uses internationally reported emission factors without testing their applicability.

  5. Price floors for emissions trading

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Peter John, E-mail: Peter.J.Wood@anu.edu.a [Resource Management in Asia Pacific Program, Crawford School of Economics and Government, Australian National University, Canberra ACT 0200 (Australia); Jotzo, Frank, E-mail: frank.jotzo@anu.edu.a [Resource Management in Asia Pacific Program, Crawford School of Economics and Government, Australian National University, Canberra ACT 0200 (Australia)

    2011-03-15

    Price floors in greenhouse gas emissions trading schemes can guarantee minimum abatement efforts if prices are lower than expected, and they can help manage cost uncertainty, possibly as complements to price ceilings. Provisions for price floors are found in several recent legislative proposals for emissions trading. Implementation however has potential pitfalls. Possible mechanisms are government commitments to buy back permits, a reserve price at auction, or an extra fee or tax on acquittal of emissions permits. Our analysis of these alternatives shows that the fee approach has budgetary advantages and is more compatible with international permit trading than the alternatives. It can also be used to implement more general hybrid approaches to emissions pricing. - Research highlights: {yields} Price floors for emissions trading schemes guarantee a minimum carbon price. {yields} Price floors mean that emissions can be less than specified by the ETS cap. {yields} We examine how price floors can relate to different policy objectives. {yields} We compare different mechanisms for implementing a price floor. {yields} We find that a mechanism where there is an extra tax or fee has advantages.

  6. PEMS. Advanced predictive emission monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Sandvig Nielsen, J.

    2010-07-15

    In the project PEMS have been developed for boilers, internal combustion engines and gas turbines. The PEMS models have been developed using two principles: The one called ''first principles'' is based on thermo-kinetic modeling of the NO{sub x}-formation by modeling conditions (like temperature, pressure and residence time) in the reaction zones. The other one is data driven using artificial neural network (ANN) and includes no physical properties and no thermo-kinetic formulation. Models of first principles have been developed for gas turbines and gas engines. Data driven models have been developed for gas turbines, gas engines and boilers. The models have been tested on data from sites located in Denmark and the Middle East. Weel and Sandvig has conducted the on-site emission measurements used for development and testing the PEMS models. For gas turbines, both the ''first principles'' and the data driven models have performed excellent considering the ability to reproduce the emission levels of NO{sub x} according to the input variables used for calibration. Data driven models for boilers and gas engines have performed excellent as well. The rather comprehensive first principle model, developed for gas engines, did not perform as well in the prediction of NO{sub x}. Possible a more complex model formulation is required for internal combustion engines. In general, both model types have been validated on data extracted from the data set used for calibration. The data for validation have been selected randomly as individual samplings, and is scattered over the entire measuring campaign. For one natural gas engine a secondary measuring campaign was conducted half a year later than the campaign used for training the data driven model. In the meantime, this engine had been through a refurbishment that included new pistons, piston rings and cylinder linings and cleaning of the cylinder heads. Despite the refurbishment, the

  7. Greenhouse Gas Emissions from Agricultural Production

    DEFF Research Database (Denmark)

    Bennetzen, Eskild Hohlmann

    . The KPI enables combined analyses of changes in total emissions, emissions per area and emissions per product. Also, the KPI can be used to assess how a change in each GHG emission category affects the change in total emissions; thus pointing to where things are going well and where things are going less......-production, respectively. Only emissions from energy use have increased more than production. Our projected BAU scenarios suggest that emissions may be further decoupled by 20 – 55% giving absolute agricultural emissions in the range of 8.2 to 14.5 Pg CO2-eq. yr-1 by 2050; lower than most other suggest from estimates...... that do not allow for decoupling. In Paper III agricultural production and GHG emissions since 1970, are analysed for nine world regions. Decoupling of emissions from production shows vast regional differences. In general, the more developed regions show the lowest emissions per unit of agricultural...

  8. Real-world activity, fuel use, and emissions of diesel side-loader refuse trucks

    Science.gov (United States)

    Sandhu, Gurdas S.; Frey, H. Christopher; Bartelt-Hunt, Shannon; Jones, Elizabeth

    2016-03-01

    Diesel refuse trucks have the worst fuel economy of onroad highway vehicles. The real-world effectiveness of recently introduced emission controls during low speed and low engine load driving has not been verified for these vehicles. A portable emission measurement system (PEMS) was used to measure rates of fuel use and emissions on six side-loader refuse trucks. The objectives were to: (1) characterize activity, fuel use, and emissions; (2) evaluate variability between cycles and trucks; and (3) compare results with the MOVES emission factor model. Quality assured data cover 210,000 s and 550 miles of operation during which the trucks collected 4200 cans and 50 tons of waste material. The average fuel economy was 2.6 mpg. Trash collection contributed 70%-80% of total fuel use and emissions. The daily activity Operating Mode (OpMode) distribution and cycle average fuel use and emissions is different from previously used cycles such as Central Business District (CBD), New York Garbage Truck (NYGT), and William H. Martin (WHM). NOx emission rates for trucks with selective catalytic reduction were over 90% lower than those for trucks without. Similarly, trucks with diesel particulate filters had over 90% lower particulate matter (PM) emissions than trucks without. Compared to unloaded trucks, loaded truck averaged 18% lower fuel economy while NOx and PM emissions were higher by 65% and 16%, respectively. MOVES predicted values are highly correlated to empirical data; however, MOVES estimates are 37% lower for NOx and 300% higher for PM emission rates. The data presented here can be used to develop more representative cycles and improve emission factors for side-loader refuse trucks, which in turn can improve the accuracy of refuse truck emission inventories.

  9. Global emissions of terpenoid VOCs from terrestrial vegetation in the last millennium

    Science.gov (United States)

    Acosta Navarro, J. C.; Smolander, S.; Struthers, H.; Zorita, E.; Ekman, A. M. L.; Kaplan, J. O.; Guenther, A.; Arneth, A.; Riipinen, I.

    2014-06-01

    We investigated the millennial variability (1000 A.D.-2000 A.D.) of global biogenic volatile organic compound (BVOC) emissions by using two independent numerical models: The Model of Emissions of Gases and Aerosols from Nature (MEGAN), for isoprene, monoterpene, and sesquiterpene, and Lund-Potsdam-Jena-General Ecosystem Simulator (LPJ-GUESS), for isoprene and monoterpenes. We found the millennial trends of global isoprene emissions to be mostly affected by land cover and atmospheric carbon dioxide changes, whereas monoterpene and sesquiterpene emission trends were dominated by temperature change. Isoprene emissions declined substantially in regions with large and rapid land cover change. In addition, isoprene emission sensitivity to drought proved to have significant short-term global effects. By the end of the past millennium MEGAN isoprene emissions were 634 TgC yr-1 (13% and 19% less than during 1750-1850 and 1000-1200, respectively), and LPJ-GUESS emissions were 323 TgC yr-1(15% and 20% less than during 1750-1850 and 1000-1200, respectively). Monoterpene emissions were 89 TgC yr-1(10% and 6% higher than during 1750-1850 and 1000-1200, respectively) in MEGAN, and 24 TgC yr-1 (2% higher and 5% less than during 1750-1850 and 1000-1200, respectively) in LPJ-GUESS. MEGAN sesquiterpene emissions were 36 TgC yr-1(10% and 4% higher than during 1750-1850 and 1000-1200, respectively). Although both models capture similar emission trends, the magnitude of the emissions are different. This highlights the importance of building better constraints on VOC emissions from terrestrial vegetation.

  10. Constraining sector-specific CO2 and CH4 emissions in the US

    Science.gov (United States)

    Miller, Scot M.; Michalak, Anna M.

    2017-03-01

    This review paper explores recent efforts to estimate state- and national-scale carbon dioxide (CO2) and methane (CH4) emissions from individual anthropogenic source sectors in the US. Nearly all state and national climate change regulations in the US target specific source sectors, and detailed monitoring of individual sectors presents a greater challenge than monitoring total emissions. We particularly focus on opportunities to synthesize disparate types of information on emissions, including emission inventory data and atmospheric greenhouse gas data.We find that inventory estimates of sector-specific CO2 emissions are sufficiently accurate for policy evaluation at the national scale but that uncertainties increase at state and local levels. CH4 emission inventories are highly uncertain for all source sectors at all spatial scales, in part because of the complex, spatially variable relationships between economic activity and CH4 emissions. In contrast to inventory estimates, top-down estimates use measurements of atmospheric mixing ratios to infer emissions at the surface; thus far, these efforts have had some success identifying urban CO2 emissions and have successfully identified sector-specific CH4 emissions in several opportunistic cases. We also describe a number of forward-looking opportunities that would aid efforts to estimate sector-specific emissions: fully combine existing top-down datasets, expand intensive aircraft measurement campaigns and measurements of secondary tracers, and improve the economic and demographic data (e.g., activity data) that drive emission inventories. These steps would better synthesize inventory and top-down data to support sector-specific emission reduction policies.

  11. Variability in carbon exchange of European croplands

    DEFF Research Database (Denmark)

    Eddy J, Moors; Jacobs, Cor; Jans, Wilma

    2010-01-01

    as the standard deviation of these cropping periods was 251 gC m-2. These numbers do not include lateral inputs such as the carbon content of applied manure, nor the carbon exchange out of the cropping period. Both are expected to have a major effect on the C budget of high energy summer crops such as maize. NEE...... measured at these sites or reported at the NUTS2 level dataset of EUROSTAT is a relatively poor predictor of NEE. To investigate the difference in the variability in CO2 emissions of different crops at the same location and to compare this variation with the variation of the same crop at different...... locations and with the inter-annual variation the measured dataset at the flux sites was extended with simulated data. These simulations show that the variability in carbon exchange is determined by: firstly the choice of crop and the location and to a lesser extent by the yearly differences in climate....

  12. Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

    Science.gov (United States)

    Shetty, Suraj K.

    Mercury (Hg) is a toxic pollutant and is important to understand its cycling in the environment. In this dissertation, a number of modeling investigations were conducted to better understand the emission from natural surfaces, the source-receptor relationship of the emissions, and emission reduction of atmospheric mercury. The first part of this work estimates mercury emissions from vegetation, soil and water surfaces using a number of natural emission processors and detailed (LAI) Leaf Area Index data from GIS (Geographic Information System) satellite products. East Asian domain was chosen as it contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. The estimated annual natural mercury emissions (gaseous elemental mercury) in the domain are 834 Mg yr-1 with 462 Mg yr-1 contributing from China. Compared to anthropogenic sources, natural sources show greater seasonal variability (highest in simmer). The emissions are significant, sometimes dominant, contributors to total mercury emission in the regions. The estimates provide possible explanation for the gaps between the anthropogenic emission estimates based on activity data and the emission inferred from field observations in the regions. To understand the contribution of domestic emissions to mercury deposition in the United States, the second part of the work applies the mercury model of Community Multi-scale Air Quality Modeling system (CMAQ-Hg v4.6) to apportion the various emission sources attributing to the mercury wet and dry deposition in the 6 United States receptor regions. Contributions to mercury deposition from electric generating units (EGU), iron and steel industry (IRST), industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC) in domain was estimated. The model results for 2005 compared reasonably well to field observations made by MDN (Mercury Deposition Network

  13. Spatial variability of groundwater recharge - I. Is it really variable?

    OpenAIRE

    De Silva, RP

    2004-01-01

    The spatial variability of recharge is an important consideration in estimating recharge especially as all methods of estimating it are 'point' estimates and in most places recharge varies in space. This paper along with the accompanying paper attempts to find a suitable answer to the question of taking this variability into account in estimating groundwater recharge. This paper attempts to determine if recharge is actually varying in space and that this is 'true' variability and that it is n...

  14. Comparison of emissions from on-road sources using a mobile laboratory under various driving and operational sampling modes

    Directory of Open Access Journals (Sweden)

    M. Zavala

    2009-01-01

    Full Text Available Mobile sources produce a significant fraction of the total anthropogenic emissions burden in large cities and have harmful effects on air quality at multiple spatial scales. Mobile emissions are intrinsically difficult to estimate due to the large number of parameters affecting the emissions variability within and across vehicles types. The MCMA-2003 Campaign in Mexico City has showed the utility of using a mobile laboratory to sample and characterize specific classes of motor vehicles to better quantify their emissions characteristics as a function of their driving cycles. The technique clearly identifies "high emitter" vehicles via individual exhaust plumes, and also provides fleet average emission rates. We have applied this technique to Mexicali during the Border Ozone Reduction and Air Quality Improvement Program (BORAQIP for the Mexicali-Imperial Valley in 2005. We analyze the variability of measured emission ratios for emitted NOx, CO, specific VOCs, NH3, and some primary fine particle components and properties by deploying a mobile laboratory in roadside stationary sampling, chase and fleet average operational sampling modes. The measurements reflect various driving modes characteristic of the urban fleets. The observed variability for all measured gases and particle emission ratios is greater for the chase and roadside stationary sampling than for fleet average measurements. The fleet average sampling mode captured the effects of traffic conditions on the measured on-road emission ratios, allowing the use of fuel-based emission ratios to assess the validity of traditional "bottom-up" emissions inventories. Using the measured on-road emission ratios, we estimate CO and NOx mobile emissions of 175±62 and 10.4±1.3 metric tons/day, respectively, for the gasoline vehicle fleet in Mexicali. Comparisons with similar on-road emissions data from Mexico City indicated that fleet average NO emission ratios were

  15. Variable Sampling Mapping

    Science.gov (United States)

    Smith, Jeffrey, S.; Aronstein, David L.; Dean, Bruce H.; Lyon, Richard G.

    2012-01-01

    The performance of an optical system (for example, a telescope) is limited by the misalignments and manufacturing imperfections of the optical elements in the system. The impact of these misalignments and imperfections can be quantified by the phase variations imparted on light traveling through the system. Phase retrieval is a methodology for determining these variations. Phase retrieval uses images taken with the optical system and using a light source of known shape and characteristics. Unlike interferometric methods, which require an optical reference for comparison, and unlike Shack-Hartmann wavefront sensors that require special optical hardware at the optical system's exit pupil, phase retrieval is an in situ, image-based method for determining the phase variations of light at the system s exit pupil. Phase retrieval can be used both as an optical metrology tool (during fabrication of optical surfaces and assembly of optical systems) and as a sensor used in active, closed-loop control of an optical system, to optimize performance. One class of phase-retrieval algorithms is the iterative transform algorithm (ITA). ITAs estimate the phase variations by iteratively enforcing known constraints in the exit pupil and at the detector, determined from modeled or measured data. The Variable Sampling Mapping (VSM) technique is a new method for enforcing these constraints in ITAs. VSM is an open framework for addressing a wide range of issues that have previously been considered detrimental to high-accuracy phase retrieval, including undersampled images, broadband illumination, images taken at or near best focus, chromatic aberrations, jitter or vibration of the optical system or detector, and dead or noisy detector pixels. The VSM is a model-to-data mapping procedure. In VSM, fully sampled electric fields at multiple wavelengths are modeled inside the phase-retrieval algorithm, and then these fields are mapped to intensities on the light detector, using the properties

  16. Estimation of emissions of nonmethane organic compounds from a closed landfill site using a landfill gas emission model

    Energy Technology Data Exchange (ETDEWEB)

    Nwachukwu, A.N. [Williamson Research Centre for Molecular Environmental Sciences, School of Earth, Atmospheric and Environmental Science, University of Manchester M13 9PL (United Kingdom); Diya, A.W. [Health Sciences Research Group, School of Medicine, University of Manchester M13 9PL (United Kingdom)

    2013-07-01

    Nonmethane organic compounds (NMOC) emissions from landfills often constitute significant risks both to human health and the general environment. To date very little work has been done on tracking the emissions of NMOC from landfills. To this end, a concerted effort was made to investigate the total annual mass emission rate of NMOC from a closed landfill site in South Manchester, United Kingdom. This was done by using field estimates of NMOC concentration and the landfill parameters into the Landfill Gas Emission Model embedded in ACTS and RISK software. Two results were obtained: (i) a deterministic outcome of 1.7218 x 10-7 kg/year, which was calculated from mean values of the field estimates of NMOC concentration and the landfill parameters, and (ii) a probabilistic outcome of 1.66 x 10-7 - 1.78 x 10-7 kg/year, which is a range of value obtained after Monte Carlo simulation of the uncertain parameters of the landfill including NMOC concentration. A comparison between these two results suggests that the probabilistic outcome is a more representative and reliable estimate of the total annual mass emission of NMOC especially given the variability of the parameters of the model. Moreover, a comparison of the model result and the safety standard of 5.0 x 10-5 kg/year indicate that the mass emission of NMOC from the studied landfill is significantly less than previously thought. However, given that this can accumulate to a dangerous level over a long period of time (such as the age of this landfill site); it may have started affecting the health of the people living within the vicinity of the landfill. A case is therefore made for more studies to be carried out on the emissions of other gases such as CH4 and CO2 from the studied landfill site, as this would help to understand the synergistic effect of the various gases being emitted from the landfill.

  17. The challenges of reducing greenhouse gas emissions and air pollution through energy sources: evidence from a panel of developed countries.

    Science.gov (United States)

    Akhmat, Ghulam; Zaman, Khalid; Shukui, Tan; Sajjad, Faiza; Khan, Muhammad Azhar; Khan, Muhammad Zahir

    2014-06-01

    The objective of the study is to investigate the long-run relationship between climatic factors (i.e., greenhouse gas emissions, agricultural methane emissions, and industrial nitrous oxide emission), air pollution (i.e., carbon dioxide emissions), and energy sources (i.e., nuclear energy; oil, gas, and coal energy; and fossil fuel energy) in the panel of 35 developed countries (including EU-15, new EU member states, G-7, and other countries) over a period of 1975-2012. In order to achieve this objective, the present study uses sophisticated panel econometric techniques including panel cointegration, panel fully modified OLS (FMOLS), and dynamic OLS (DOLS). The results show that there is a long-run relationship between the variables. Nuclear energy reduces greenhouse gases and carbon emissions; however, the other emissions, i.e., agricultural methane emissions and industrial nitrous oxide, are still to increase during the study period. Electricity production from oil, gas, and coal sources increases the greenhouse gases and carbon emissions; however, the intensity to increase emissions is far less than the intensity to increase emissions through fossil fuel. Policies that reduce emissions of greenhouse gases can simultaneously alter emissions of conventional pollutants that have deleterious effects on human health and the environment.

  18. Analysis of US emissions from two mobile source emissions models: magnitude, spatial and temporal patterns, and effects on photochemical modeling outputs

    Science.gov (United States)

    Simon, H. A.; Phillips, S.; Possiel, N.; Pouliot, G.; Koupal, J.; Michaels, H.

    2011-12-01

    Recently EPA's Office of Transportation and Air Quality (OTAQ) released a new model to estimate emissions from onroad mobile sources. This new model, MOVES, is being phased in to replace the existing MOBILE6 model and has already been used in air quality modeling in support of several EPA rules. Preliminary NOx emissions estimates using monthly average temperatures and state-level fleet characteristics from MOVES are 70% higher nationwide than estimates from MOBILE6 for a 2005 annual inventory. In this talk, we will present MOVES emissions using more refined inputs including hourly temperature and speed values and county-level fleet characteristics. We compare the nationwide totals and spatial and temporal variability in emissions of NOx and VOC from the new MOVES run with the old MOBILE6 outputs for two months, January and July 2006. In addition, these emissions have been input into CMAQ photochemical modeling simulations. We present the differences in CMAQ estimates of NOx and ozone concentration across the US using MOVES versus MOBILE6 mobile source emissions inputs. In addition, we evaluate any changes in the responsiveness of the model predicted ozone concentrations to emissions reductions between the two mobile emissions models.

  19. Tropospheric Emissions: Monitoring of Pollution (TEMPO)

    Science.gov (United States)

    Zoogman, P.; Liu, X.; Suleiman, R. M.; Pennington, W. F.; Flittner, D. E.; Al-Saadi, J. A.; Hilton, B. B.; Nicks, D. K.; Newchurch, M. J.; Carr, J. L.; hide

    2016-01-01

    TEMPO (Tropospheric Emissions: Monitoring of Pollution) was selected in 2012 by NASA as the first Earth Venture Instrument, for launch between 2018 and 2021. It will measure atmospheric pollution for greater North America from space using ultraviolet and visible spectroscopy. TEMPO observes from Mexico City, Cuba, and the Bahamas to the Canadian oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution (approximately 2.1 kilometers N/S by 4.4 kilometers E/W at 36.5 degrees N, 100 degrees W). TEMPO provides a tropospheric measurement suite that includes the key elements of tropospheric air pollution chemistry, as well as contributing to carbon cycle knowledge. Measurements are made hourly from geostationary (GEO) orbit, to capture the high variability present in the diurnal cycle of emissions and chemistry that are unobservable from current low-Earth orbit (LEO) satellites that measure once per day. The small product spatial footprint resolves pollution sources at sub-urban scale. Together, this temporal and spatial resolution improves emission inventories, monitors population exposure, and enables effective emission-control strategies. TEMPO takes advantage of a commercial GEO host spacecraft to provide a modest cost mission that measures the spectra required to retrieve ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), formaldehyde (H2CO), glyoxal (C2H2O2), bromine monoxide (BrO), IO (iodine monoxide),water vapor, aerosols, cloud parameters, ultraviolet radiation, and foliage properties. TEMPO thus measures the major elements, directly or by proxy, in the tropospheric O3 chemistry cycle. Multi-spectral observations provide sensitivity to O3 in the lowermost troposphere, substantially reducing uncertainty in air quality predictions. TEMPO quantifies and tracks the evolution of aerosol loading. It provides these near-real-time air quality products that will be made publicly available. TEMPO will launch at a prime time to be the

  20. Physical and chemical characterisation of PM emissions from two ships operating in European Emission Control Areas

    Science.gov (United States)

    Moldanová, J.; Fridell, E.; Winnes, H.; Holmin-Fridell, S.; Boman, J.; Jedynska, A.; Tishkova, V.; Demirdjian, B.; Joulie, S.; Bladt, H.; Ivleva, N. P.; Niessner, R.

    2013-12-01

    .1-0.8% and 0.1-0.6% of fuel S converted to PM sulphate for HFO and MGO, respectively. Scanning transmission electron microscopy (STEM) images of the collected PM showed three different types of particles: relatively pure soot; char and char-mineral particles; and amorphous, probably organic particles containing inorganic impurities. The maps of elements obtained from STEM showed a heterogeneous composition of primary soot particles with respect to the trace metals and sulphur. Temperature-programmed oxidation (TPO) of PM showed higher soot oxidation reactivity compared to automotive diesel soot, PM from the HFO exhaust being more reactive than PM from the MGO exhaust. Oxidative potential measured as the rate of consumption of Dithiothreitol (DTT) was for the first time measured on PM from ship exhaust. The obtained values were between 0.01 and 0.04 nmol DTT min-1 μg-1 PM, which is quite similar to oxidative potentials of PM collected at urban and traffic sites. The data obtained during the experiments add information about emission factors for both gaseous and PM-bound compounds from ship engines using different fuels and under different engine-load conditions. Observed variability of the EFs illustrates uncertainties of these emission factors as a result of influences from fuel and lubricant composition, from differences between individual engines and from the differences in sampling conditions.

  1. Comparing Top-down and Bottom-up Estimates of Methane Emissions across Multiple U.S. Basins Provides Insights into National Oil and Gas Emissions and Mitigation Strategies

    Science.gov (United States)

    Hamburg, S.; Alvarez, R.; Lyon, D. R.; Zavala-Araiza, D.

    2016-12-01

    Several recent studies quantified regional methane emissions in U.S. oil and gas (O&G) basins using top-down approaches such as airborne mass balance measurements. These studies apportioned total methane emissions to O&G based on hydrocarbon ratios or subtracting bottom-up estimates of other sources. In most studies, top-down estimates of O&G methane emissions exceeded bottom-up emission inventories. An exception is the Barnett Shale Coordinated Campaign, which found agreement between aircraft mass balance estimates and a custom emission inventory. Reconciliation of Barnett Shale O&G emissions depended on two key features: 1) matching the spatial domains of top-down and bottom-up estimates, and 2) accounting for fat-tail sources in site-level emission factors. We construct spatially explicit custom emission inventories for domains with top-down O&G emission estimates in eight major U.S. oil and gas production basins using a variety of data sources including a spatially-allocated U.S. EPA Greenhouse Gas Inventory, the EPA Greenhouse Gas Reporting Program, state emission inventories, and recently published measurement studies. A comparison of top-down and our bottom-up estimates of O&G emissions constrains the gap between these approaches and elucidates regional variability in production-normalized loss rates. A comparison of component-level and site-level emission estimates of production sites in the Barnett Shale region - where comprehensive activity data and emissions estimates are available - indicates that abnormal process conditions contribute about 20% of regional O&G emissions. Combining these two analyses provides insights into the relative importance of different equipment, processes, and malfunctions to emissions in each basin. These data allow us to estimate the U.S. O&G supply chain loss rate, recommend mitigation strategies to reduce emissions from existing infrastructure, and discuss how a similar approach can be applied internationally.

  2. Mobile flying platform for monitoring of households smoke emission selected parameters

    OpenAIRE

    Adam Szade; Adam Hamerla; Krystian Kadlewicz; Marcin Głodniok

    2018-01-01

    The Central Mining Institute in Katowice has developed a measuring platform in response to the growing need for rapid determination of variable physicochemical, smoke emission from of single-family buildings, as well as from small local heating and production plants. The key role here is the application of a drone as a mobile media for measuring devices, which provides simultaneous in situ measurement of basic parameters of household smoke emission supplemented by images from cameras and GPS ...

  3. Megacity and country emissions from combustion sources-Buenos Aires-Argentina

    Science.gov (United States)

    Dawidowski, L.; Gomez, D.; Matranga, M.; D'Angiola, A.; Oreggioni, G.

    2010-12-01

    Historic time series (1970-2006) emissions of greenhouse gases and air pollutants arising from stationary and mobile combustion sources were estimated at national level for Argentina and at regional level for the metropolitan area of Buenos Aires (MABA). All emissions were estimated using a bottom-up approach following the IPCC good practice guidance. For mobile sources, national emissions include all transport categories. Regional emissions account thus far only for on-road. For national emissions, methodologies and guidance by the IPCC were employed, applying the highest possible tier and using: i)country-specific emission factors for carbon and sulphur and technology-based information for other species, ii)activity data from energy balance series (1970-2007), and iii)complementary information concerning the non-energy use of fuels. Regional emissions in 2006 were estimated in-depth using a technology-based approach for the city of Buenos Aires (CBA) and the 24 neighboring districts composing the MABA. A regional emissions factors database was developed to better characterize Latin American fleets and driving conditions employing COPERT III-IV algorithms and emission factors measured in dynamometers and circulating vehicles in Argentina, Brazil, Chile and Colombia. Past emissions were back estimated from 2005 to 1970 using the best available information, which differs greatly among categories, spatial disaggregation and time periods. The time series of stationary and mobile combustion sources at the national and regional level allowed the identification of distinct patterns. National greenhouse gas emissions in 2006 amounted to ~ 150 million ton CO2-equivalent, 70% of which were contributed by stationary sources. On-road transport was the major contributor within mobile sources (28.1 %). The increasing emissions trends are dominated by on-road transport, agriculture and residential categories while the variability is largely associated with energy industries

  4. An emission module for ICON-ART 2.0: implementation and simulations of acetone

    Directory of Open Access Journals (Sweden)

    M. Weimer

    2017-06-01

    Full Text Available We present a recently developed emission module for the ICON (ICOsahedral Non-hydrostatic-ART (Aerosols and Reactive Trace gases modelling framework. The emission module processes external flux data sets and increments the tracer volume mixing ratios in the boundary layer accordingly. The performance of the emission module is illustrated with simulations of acetone, using a simplified chemical depletion mechanism based on a reaction with OH and photolysis only. In our model setup, we calculate a tropospheric acetone lifetime of 33 days, which is in good agreement with the literature. We compare our results with ground-based as well as with airborne IAGOS-CARIBIC measurements in the upper troposphere and lowermost stratosphere (UTLS in terms of phase and amplitude of the annual cycle. In all our ICON-ART simulations the general seasonal variability is well represented but uncertainties remain concerning the magnitude of the acetone mixing ratio in the UTLS region. In addition, the module for online calculations of biogenic emissions (MEGAN2.1 is implemented in ICON-ART and can replace the offline biogenic emission data sets. In a sensitivity study we show how different parametrisations of the leaf area index (LAI change the emission fluxes calculated by MEGAN2.1 and demonstrate the importance of an adequate treatment of the LAI within MEGAN2.1. We conclude that the emission module performs well with offline and online emission fluxes and allows the simulation of the annual cycles of emissions-dominated substances.

  5. An emission module for ICON-ART 2.0: implementation and simulations of acetone

    Science.gov (United States)

    Weimer, Michael; Schröter, Jennifer; Eckstein, Johannes; Deetz, Konrad; Neumaier, Marco; Fischbeck, Garlich; Hu, Lu; Millet, Dylan B.; Rieger, Daniel; Vogel, Heike; Vogel, Bernhard; Reddmann, Thomas; Kirner, Oliver; Ruhnke, Roland; Braesicke, Peter

    2017-06-01

    We present a recently developed emission module for the ICON (ICOsahedral Non-hydrostatic)-ART (Aerosols and Reactive Trace gases) modelling framework. The emission module processes external flux data sets and increments the tracer volume mixing ratios in the boundary layer accordingly. The performance of the emission module is illustrated with simulations of acetone, using a simplified chemical depletion mechanism based on a reaction with OH and photolysis only. In our model setup, we calculate a tropospheric acetone lifetime of 33 days, which is in good agreement with the literature. We compare our results with ground-based as well as with airborne IAGOS-CARIBIC measurements in the upper troposphere and lowermost stratosphere (UTLS) in terms of phase and amplitude of the annual cycle. In all our ICON-ART simulations the general seasonal variability is well represented but uncertainties remain concerning the magnitude of the acetone mixing ratio in the UTLS region. In addition, the module for online calculations of biogenic emissions (MEGAN2.1) is implemented in ICON-ART and can replace the offline biogenic emission data sets. In a sensitivity study we show how different parametrisations of the leaf area index (LAI) change the emission fluxes calculated by MEGAN2.1 and demonstrate the importance of an adequate treatment of the LAI within MEGAN2.1. We conclude that the emission module performs well with offline and online emission fluxes and allows the simulation of the annual cycles of emissions-dominated substances.

  6. Halocarbon emissions from the United States and Mexico and their global warming potential.

    Science.gov (United States)

    Millet, Dylan B; Atlas, Elliot L; Blake, Donald R; Blake, Nicola J; Diskin, Glenn S; Holloway, John S; Hudman, Rynda C; Meinardi, Simone; Ryerson, Thomas B; Sachse, Glen W

    2009-02-15

    We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogenic CO source, but suggest a 30% underestimate of Mexican emissions. We develop an optimized CO emission inventory on this basis and quantify halocarbon emissions from their measured enhancements relative to CO. Emissions continue for many compounds restricted under the Montreal Protocol, and we show that halocarbons make up an important fraction of the total greenhouse gas source for both countries: our best estimate is 9% (uncertainty range 6-12%) and 32% (21-52%) of equivalent CO2 emissions for the U.S. and Mexico, respectively, on a 20 year time scale. Performance of bottom-up emission inventories is variable, with underestimates for some compounds and overestimates for others. Ongoing methylchloroform emissions are significant in the U.S. (2.8 Gg/y in 2004-2006), in contrast to bottom-up estimates (< 0.05 Gg), with implications for tropospheric OH calculations. Mexican methylchloroform emissions are minor.

  7. Synchronization of cubic distortion spontaneous otoacoustic emissions

    NARCIS (Netherlands)

    van Dijk, P; Wit, HP

    A spontaneous otoacoustic emission spectrum may contain equally spaced emission peaks. Then, two peaks, at frequencies, f(1) and f(2), respectively, apparently generate a distortion product at f(d)=2f(1)-f(2) [or 2f(2)-f(1)]. For the three emission peaks of nine of such triplets tin six emission

  8. 47 CFR 27.53 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... bandwidth of at least 1 percent of the emission bandwidth of the fundamental emission of the transmitter may... bandwidth of the fundamental emission of the transmitter may be employed. The emission bandwidth is defined... primary purpose of transmitting video programming shall be attenuated at the 6 MHz channel edges at least...

  9. Soil Greenhouse Gas Emissions from a Subtropical Mangrove in Hong Kong

    Science.gov (United States)

    Lai, D. Y. F.; Xu, J.

    2014-12-01

    The concept of "blue carbon" has received increasing attention recently, which points to the potential role of vegetated coastal wetlands in carbon sequestration. Yet, the magnitude and controls of greenhouse gas emissions from coastal wetland ecosystems, especially mangroves in the subtropical regions, are still largely unknown. In this study, we conducted chamber measurements in the Mai Po Marshes Nature Reserve of Hong Kong at monthly intervals to characterize the spatial and temporal variability of the emission of greenhouse gases, including CO2, CH4 and N2O from mangrove soils, and examine the influence of environmental and biotic variables on greenhouse gas fluxes. We found the highest mean CH4 and N2O emissions in autumn and the highest CO2 flux in summer. Along the tidal gradient, we observed significantly higher CH4 and N2O emissions from the middle zones and landward zones, respectively, while no clear spatial variation of CO2 emissions was observed. There were significantly higher soil greenhouse gas emissions from sites dominated by Avicennia marina than those dominated by Kandelia obovata, which might be due to the presence of pneumatophores which facilitated gas transport. We found a significant, negative correlation between CH4 flux and soil NO3-N concentration, while CO2 flux was positively correlation with total Kjeldahl nitrogen content. Soil temperature was positively correlated with the emissions of all three greenhouse gases, while water table depth was positively and negatively correlated with CH4 and N2O emissions, respectively. Our findings demonstrate the high spatial and temporal variability of greenhouse gas emissions from mangrove soils which could be attributed in part to the differences in environmental conditions and dominant plant species.

  10. Comparative study on performances of a continuously variable transmission used in two different powertrain architectures

    Science.gov (United States)

    Sibiceanu, A. R.; Ivan, F.; Nicolae, V.; Iorga, A.; Cioroianu, C.

    2017-08-01

    Given the importance of reducing carbon emissions from road transport, price and security of oil supply, hybrid electric vehicle can provide a viable alternative solution to conventional vehicles, equipped with thermal engines, which use fossil fuels. Based on the growing trends of new vehicles sales, which include hybrid and electric vehicles closely associated with their use in terms of harmful emissions, strict regulations are established. In this paper were created models of thermal and hybrid electric powertrains groups, using computer simulation program AVL Cruise, making a comparative study using petroleum fuels for continuously variable transmission. The results obtained highlights both fuel consumption as well as pollutant emissions.

  11. HOW NORMAL IS VARIABLE, OR HOW VARIABLE IS NORMAL

    NARCIS (Netherlands)

    TOUWEN, BCL

    Variability is an important property of the central nervous system, and it shows characteristic changes during infancy and childhood. The large amount of variations in the performance of sensomotor functions in infancy is called indiscriminate or primary variability. During toddling age the child

  12. Variable Speed Rotor System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable speed rotors will give helicopters several advantages: higher top speed, greater fuel efficiency, momentary emergency over-power, resonance detuning...

  13. The Hubble Catalog of Variables

    Directory of Open Access Journals (Sweden)

    Sokolovsky K.

    2017-01-01

    Full Text Available We aim to construct an exceptionally deep (V ≲ 27 catalog of variable objects in selected Galactic and extragalactic fields visited multiple times by the Hubble Space Telescope (HST. While HST observations of some of these fields were searched for specific types of variables before (most notably, the extragalactic Cepheids, we attempt a systematic study of the population of variable objects of all types at the magnitude range not easily accessible with ground-based telescopes. The variability timescales that can be probed range from hours to years depending on how often a particular field has been visited. For source extraction and cross-matching of sources between visits we rely on the Hubble Source Catalog which includes 107 objects detected with WFPC2, ACS, and WFC3 HST instruments. The lightcurves extracted from the HSC are corrected for systematic effects by applying local zero-point corrections and are screened for bad measurements. For each lightcurve we compute variability indices sensitive to a broad range of variability types. The indices characterize the overall lightcurve scatter and smoothness. Candidate variables are selected as having variability index values significantly higher than expected for objects of similar brightness in the given set of observations. The Hubble Catalog of Variables will be released in 2018.

  14. Enteric methane emissions and their response to agro-ecological and livestock production systems dynamics in Zimbabwe.

    Science.gov (United States)

    Svinurai, Walter; Mapanda, Farai; Sithole, Dingane; Moyo, Elisha N; Ndidzano, Kudzai; Tsiga, Alois; Zhakata, Washington

    2018-03-01

    Without disregarding its role as one of the key sources of sustainable livelihoods in Zimbabwe and other developing countries, livestock production contributes significantly to greenhouse gas (GHG) emissions through enteric fermentation. For the livestock sector to complement global efforts to mitigate climate change, accurate estimations of GHG emissions are required. Methane emissions from enteric fermentation in Zimbabwe were quantified over 35years under four production systems and five agro-ecological regions. The Intergovernmental Panel on Climate Change emission factor methodology was used to derive CH 4 emissions from seven livestock categories at national level. Emission intensities based on human population, domestic export of livestock meat and climate variables were used to assess emission drivers and predict future emission trends. Over the past 35years, enteric fermentation CH 4 emissions from all livestock categories ranged between 158.3 and 204.3Ggyear -1 . Communal lands, typified by indigenous livestock breeds, had the highest contribution of between 58% and 75% of the total annual emissions followed by livestock from large scale commercial (LSC) farms. The decreasing livestock population on LSC farms and consequent decline in production could explain the lack of a positive response of CH 4 emissions to human population growth, and decreasing emissions per capita over time at -0.3kg CH 4 capita -1 year -1 . The emissions trend showed that even if Zimbabwe's national livestock population doubles in 2030 relative to the 2014 estimates, the country would still remain with similar magnitude of CH 4 emission intensity as that of 1980. No significant correlations (P>0.05) were found between emissions and domestic export of beef and pork. Further research on enhanced characterisation of livestock species, population and production systems, as well as direct measurements and modelling of emissions from indigenous and exotic livestock breeds were

  15. Correlation analysis between ceramic insulator pollution and acoustic emissions

    Directory of Open Access Journals (Sweden)

    Benjamín Álvarez-Nasrallah

    2015-01-01

    Full Text Available Most of the studies related to insulator pollution are normally performed based on individual analysis among leakage current, relative humidity and equivalent salt deposit density (ESDD. This paper presents a correlation analysis between the leakage current and the acoustic emissions measured in a 230 kV electrical substations in the city of Barranquilla, Colombia. Furthermore, atmospheric variables were considered to develop a characterization model of the insulator contamination process. This model was used to demonstrate that noise emission levels are a reliable indicator to detect and characterize pollution on high voltage insulators. The correlation found amount the atmospheric, electrical and sound variables allowed to determine the relations for the maintenance of ceramic insulators in high-polluted areas. In this article, the results on the behavior of the leakage current in ceramic insulators and the sound produced with different atmospheric conditions are shown, which allow evaluating the best time to clean the insulator at the substation. Furthermore, by experimentation on site and using statistical models, the correlation between ambient variables and the leakage current of insulators in an electrical substation was obtained. Some of the problems that bring the external noise were overcome using multiple microphones and specialized software that enabled properly filter the sound and better measure the variables.

  16. The causal link among militarization, economic growth, CO2 emission, and energy consumption.

    Science.gov (United States)

    Bildirici, Melike E

    2017-02-01

    This paper examines the long-run and the causal relationship among CO2 emissions, militarization, economic growth, and energy consumption for USA for the period 1960-2013. Using the bound test approach to cointegration, a short-run as well as a long-run relationship among the variables with a positive and a statistically significant relationship between CO2 emissions and militarization was found. To determine the causal link, MWALD and Rao's F tests were applied. According to Rao's F tests, the evidence of a unidirectional causality running from militarization to CO2 emissions, from energy consumption to CO2 emissions, and from militarization to energy consumption all without a feedback was found. Further, the results determined that 26% of the forecast-error variance of CO2 emissions was explained by the forecast error variance of militarization and 60% by energy consumption.

  17. Methane emissions from Pantanal, South America, during the low water season: toward more comprehensive sampling.

    Science.gov (United States)

    Bastviken, David; Santoro, Ana Lucia; Marotta, Humberto; Pinho, Luana Queiroz; Calheiros, Debora Fernandes; Crill, Patrick; Enrich-Prast, Alex

    2010-07-15

    Freshwater environments contribute 75% of the natural global methane (CH(4)) emissions. While there are indications that tropical lakes and reservoirs emit 58-400% more CH(4) per unit area than similar environments in boreal and temperate biomes, direct measurements of tropical lake emissions are scarce. We measured CH(4) emissions from 16 natural shallow lakes in the Pantanal region of South America, one of the world's largest tropical wetland areas, during the low water period using floating flux chambers. Measured fluxes ranged from 3.9 to 74.2 mmol m(-2) d(-1) with the average from all studied lakes being 8.8 mmol m(-2) d(-1) (131.8 mg CH(4) m(-2) d(-1)), of which ebullition accounted for 91% of the flux (28-98% on individual lakes). Diel cycling of emission rates was observed and therefore 24-h long measurements are recommended rather than short-term measurements not accounting for the full diel cycle. Methane emission variability within a lake may be equal to or more important than between lake variability in floodplain areas as this study identified diverse habitats within lakes having widely different flux rates. Future measurements with static floating chambers should be based on many individual chambers distributed in the various subenvironments of a lake that may differ in emissions in order to account for the within lake variability.

  18. The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1: an extended and updated framework for modeling biogenic emissions

    Directory of Open Access Journals (Sweden)

    A. B. Guenther

    2012-11-01

    Full Text Available The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1 is a modeling framework for estimating fluxes of biogenic compounds between terrestrial ecosystems and the atmosphere using simple mechanistic algorithms to account for the major known processes controlling biogenic emissions. It is available as an offline code and has also been coupled into land surface and atmospheric chemistry models. MEGAN2.1 is an update from the previous versions including MEGAN2.0, which was described for isoprene emissions by Guenther et al. (2006 and MEGAN2.02, which was described for monoterpene and sesquiterpene emissions by Sakulyanontvittaya et al. (2008. Isoprene comprises about half of the total global biogenic volatile organic compound (BVOC emission of 1 Pg (1000 Tg or 1015 g estimated using MEGAN2.1. Methanol, ethanol, acetaldehyde, acetone, α-pinene, β-pinene, t-β-ocimene, limonene, ethene, and propene together contribute another 30% of the MEGAN2.1 estimated emission. An additional 20 compounds (mostly terpenoids are associated with the MEGAN2.1 estimates of another 17% of the total emission with the remaining 3% distributed among >100 compounds. Emissions of 41 monoterpenes and 32 sesquiterpenes together comprise about 15% and 3%, respectively, of the estimated total global BVOC emission. Tropical trees cover about 18% of the global land surface and are estimated to be responsible for ~80% of terpenoid emissions and ~50% of other VOC emissions. Other trees cover about the same area but are estimated to contribute only about 10% of total emissions. The magnitude of the emissions estimated with MEGAN2.1 are within the range of estimates reported using other approaches and much of the differences between reported values can be attributed to land cover and meteorological driving variables. The offline version of MEGAN2.1 source code and driving variables is available from

  19. Importance of soil NO emissions for the total atmospheric NOxbudget of Saxony, Germany

    DEFF Research Database (Denmark)

    Molina-Herrera, Saúl; Haas, Edwin; Grote, Rüdiger

    2017-01-01

    the LandscapeDNDC model to a GIS database holding spatially explicit data on climate, land use, soil and management to quantify the contribution of soil biogenic NO emissions to the total NOxbudget for the State of Saxony, Germany. Our calculations show that soils of both agricultural and forest systems...... are significant sources and contribute to about 8% (uncertainty range: 6–13%) to the total annual tropospheric NOxbudget for Saxony. However, the contributions of soil NO emission to total tropospheric NOxshowed a high spatial variability and in some rural regions such as the Ore Mts., simulated soil NO emissions...

  20. Scaling laws for perturbations in the ocean–atmosphere system following large CO2 emissions

    Directory of Open Access Journals (Sweden)

    N. Towles

    2015-07-01

    Full Text Available Scaling relationships are found for perturbations to atmosphere and ocean variables from large transient CO2 emissions. Using the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir (LOSCAR model (Zeebe et al., 2009; Zeebe, 2012b, we calculate perturbations to atmosphere temperature, total carbon, ocean temperature, total ocean carbon, pH, alkalinity, marine-sediment carbon, and carbon-13 isotope anomalies in the ocean and atmosphere resulting from idealized CO2 emission events. The peak perturbations in the atmosphere and ocean variables are then fit to power law functions of the form of γ DαEβ, where D is the event duration, E is its total carbon emission, and γ is a coefficient. Good power law fits are obtained for most system variables for E up to 50 000 PgC and D up to 100 kyr. Although all of the peak perturbations increase with emission rate E/D, we find no evidence of emission-rate-only scaling, α + β = 0. Instead, our scaling yields α + β ≃ 1 for total ocean and atmosphere carbon and 0 < α + β < 1 for most of the other system variables.

  1. Effect of different emission inventories on modeled ozone and carbon monoxide in Southeast Asia

    Science.gov (United States)

    Amnuaylojaroen, T.; Barth, M. C.; Emmons, L. K.; Carmichael, G. R.; Kreasuwun, J.; Prasitwattanaseree, S.; Chantara, S.

    2014-12-01

    In order to improve our understanding of air quality in Southeast Asia, the anthropogenic emissions inventory must be well represented. In this work, we apply different anthropogenic emission inventories in the Weather Research and Forecasting Model with Chemistry (WRF-Chem) version 3.3 using Model for Ozone and Related Chemical Tracers (MOZART) gas-phase chemistry and Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) aerosols to examine the differences in predicted carbon monoxide (CO) and ozone (O3) surface mixing ratios for Southeast Asia in March and December 2008. The anthropogenic emission inventories include the Reanalysis of the TROpospheric chemical composition (RETRO), the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), the MACCity emissions (adapted from the Monitoring Atmospheric Composition and Climate and megacity Zoom for the Environment projects), the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS) emissions, and a combination of MACCity and SEAC4RS emissions. Biomass-burning emissions are from the Fire Inventory from the National Center for Atmospheric Research (NCAR) (FINNv1) model. WRF-Chem reasonably predicts the 2 m temperature, 10 m wind, and precipitation. In general, surface CO is underpredicted by WRF-Chem while surface O3 is overpredicted. The NO2 tropospheric column predicted by WRF-Chem has the same magnitude as observations, but tends to underpredict the NO2 column over the equatorial ocean and near Indonesia. Simulations using different anthropogenic emissions produce only a slight variability of O3 and CO mixing ratios, while biomass-burning emissions add more variability. The different anthropogenic emissions differ by up to 30% in CO emissions, but O3 and CO mixing ratios averaged over the land areas of the model domain differ by ~4.5% and ~8%, respectively, among the simulations. Biomass-burning emissions create a substantial increase for both O3 and CO by ~29% and ~16

  2. An extended Kalman-filter for regional scale inverse emission estimation

    Directory of Open Access Journals (Sweden)

    D. Brunner

    2012-04-01

    Full Text Available A Kalman-filter based inverse emission estimation method for long-lived trace gases is presented for use in conjunction with a Lagrangian particle dispersion model like FLEXPART. The sequential nature of the approach allows tracing slow seasonal and interannual changes rather than estimating a single period-mean emission field. Other important features include the estimation of a slowly varying concentration background at each measurement station, the possibility to constrain the solution to non-negative emissions, the quantification of uncertainties, the consideration of temporal correlations in the residuals, and the applicability to potentially large inversion problems. The method is first demonstrated for a set of synthetic observations created from a prescribed emission field with different levels of (correlated noise, which closely mimics true observations. It is then applied to real observations of the three halocarbons HFC-125, HFC-152a and HCFC-141b at the remote research stations Jungfraujoch and Mace Head for the quantification of emissions in Western European countries from 2006 to 2010. Estimated HFC-125 emissions are mostly consistent with national totals reported to UNFCCC in the framework of the Kyoto Protocol and show a generally increasing trend over the considered period. Results for HFC-152a are much more variable with estimated emissions being both higher and lower than reported emissions in different countries. The highest emissions of the order of 700–800 Mg yr−1 are estimated for Italy, which so far does not report HFC-152a emissions. Emissions of HCFC-141b show a continuing strong decrease as expected due to its controls in developed countries under the Montreal Protocol. Emissions from France, however, were still rather large, in the range of 700–1000 Mg yr−1 in the years 2006 and 2007 but strongly declined thereafter.

  3. Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory - Calendar Year 1998 Emissions Report

    Energy Technology Data Exchange (ETDEWEB)

    S. K. Zohner

    1999-10-01

    This report presents the 1998 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradiological emissions estimates for stationary sources.

  4. Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory - Calendar Year 1999 Emission Report

    Energy Technology Data Exchange (ETDEWEB)

    Zohner, S.K.

    2000-05-30

    This report presents the 1999 calendar year update of the Air Emission Inventory for the Idaho National Engineering and Environmental Laboratory (INEEL). The INEEL Air Emission Inventory documents sources and emissions of nonradionuclide pollutants from operations at the INEEL. The report describes the emission inventory process and all of the sources at the INEEL, and provides nonradionuclide emissions estimates for stationary sources.

  5. Nitrous oxide emissions are enhanced in a warmer and wetter world

    Science.gov (United States)

    Griffis, Timothy J.; Chen, Zichong; Baker, John M.; Wood, Jeffrey D.; Millet, Dylan B.; Lee, Xuhui; Venterea, Rodney T.; Turner, Peter A.

    2017-11-01

    Nitrous oxide (N2O) has a global warming potential that is 300 times that of carbon dioxide on a 100-y timescale, and is of major importance for stratospheric ozone depletion. The climate sensitivity of N2O emissions is poorly known, which makes it difficult to project how changing fertilizer use and climate will impact radiative forcing and the ozone layer. Analysis of 6 y of hourly N2O mixing ratios from a very tall tower within the US Corn Belt—one of the most intensive agricultural regions of the world—combined with inverse modeling, shows large interannual variability in N2O emissions (316 Gg N2O-Nṡy‑1 to 585 Gg N2O-Nṡy‑1). This implies that the regional emission factor is highly sensitive to climate. In the warmest year and spring (2012) of the observational period, the emission factor was 7.5%, nearly double that of previous reports. Indirect emissions associated with runoff and leaching dominated the interannual variability of total emissions. Under current trends in climate and anthropogenic N use, we project a strong positive feedback to warmer and wetter conditions and unabated growth of regional N2O emissions that will exceed 600 Gg N2O-Nṡy‑1, on average, by 2050. This increasing emission trend in the US Corn Belt may represent a harbinger of intensifying N2O emissions from other agricultural regions. Such feedbacks will pose a major challenge to the Paris Agreement, which requires large N2O emission mitigation efforts to achieve its goals.

  6. Nitrous oxide emissions are enhanced in a warmer and wetter world.

    Science.gov (United States)

    Griffis, Timothy J; Chen, Zichong; Baker, John M; Wood, Jeffrey D; Millet, Dylan B; Lee, Xuhui; Venterea, Rodney T; Turner, Peter A

    2017-11-07

    Nitrous oxide (N2O) has a global warming potential that is 300 times that of carbon dioxide on a 100-y timescale, and is of major importance for stratospheric ozone depletion. The climate sensitivity of N2O emissions is poorly known, which makes it difficult to project how changing fertilizer use and climate will impact radiative forcing and the ozone layer. Analysis of 6 y of hourly N2O mixing ratios from a very tall tower within the US Corn Belt-one of the most intensive agricultural regions of the world-combined with inverse modeling, shows large interannual variability in N2O emissions (316 Gg N2O-N⋅y(-1) to 585 Gg N2O-N⋅y(-1)). This implies that the regional emission factor is highly sensitive to climate. In the warmest year and spring (2012) of the observational period, the emission factor was 7.5%, nearly double that of previous reports. Indirect emissions associated with runoff and leaching dominated the interannual variability of total emissions. Under current trends in climate and anthropogenic N use, we project a strong positive feedback to warmer and wetter conditions and unabated growth of regional N2O emissions that will exceed 600 Gg N2O-N⋅y(-1), on average, by 2050. This increasing emission trend in the US Corn Belt may represent a harbinger of intensifying N2O emissions from other agricultural regions. Such feedbacks will pose a major challenge to the Paris Agreement, which requires large N2O emission mitigation efforts to achieve its goals. Published under the PNAS license.

  7. On the influence of temporal and spatial resolution of aircraft emission inventories for mesoscale modeling of pollutant dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Franzkowiak, V.; Petry, H.; Ebel, A. [Cologne Univ. (Germany). Inst. for Geophysics and Meteorology

    1997-12-31

    The sensitivity of a mesoscale chemistry transport model to the temporal and spatial resolution of aircraft emission inventories is evaluated. A statistical analysis of air traffic in the North-Atlantic flight corridor is carried out showing a highly variable, fine structured spatial distribution and a pronounced daily variation. Sensitivity studies comparing different emission scenarios reveal a strong dependency to the emission time and location of both transport and response in chemical formation of subsequent products. The introduction of a pronounced daily variation leads to a 30% higher ozone production in comparison to uniformly distributed emissions. (author) 9 refs.

  8. Variability in human body size

    Science.gov (United States)

    Annis, J. F.

    1978-01-01

    The range of variability found among homogeneous groups is described and illustrated. Those trends that show significantly marked differences between sexes and among a number of racial/ethnic groups are also presented. Causes of human-body size variability discussed include genetic endowment, aging, nutrition, protective garments, and occupation. The information is presented to aid design engineers of space flight hardware and equipment.

  9. Students' Misconceptions about Random Variables

    Science.gov (United States)

    Kachapova, Farida; Kachapov, Ilias

    2012-01-01

    This article describes some misconceptions about random variables and related counter-examples, and makes suggestions about teaching initial topics on random variables in general form instead of doing it separately for discrete and continuous cases. The focus is on post-calculus probability courses. (Contains 2 figures.)

  10. Phonological Variability in Canadian English.

    Science.gov (United States)

    de Wolf, Gaelan Dodds

    A study compared salient variables of Canadian English from two concurrent sociodialectal surveys, one for Ottawa, Ontario and one for Vancouver, British Columbia. Using the Labovian model of phonological variation in association with sociological parameters and other linguistic variables within each specific area, the analysis investigated four…

  11. A process variability control chart

    NARCIS (Netherlands)

    Riaz, M.; Does, R.J.M.M.

    2009-01-01

    In this study a Shewhart type control chart namely the Vt chart, is proposed for improvedmonitoring of the process variability of a quality characteristic of interest Y . The proposed control chart is based on the ratio type estimator of the variance using a single auxiliary variable X. It is

  12. Speed control variable rate irrigation

    Science.gov (United States)

    Speed control variable rate irrigation (VRI) is used to address within field variability by controlling a moving sprinkler’s travel speed to vary the application depth. Changes in speed are commonly practiced over areas that slope, pond or where soil texture is predominantly different. Dynamic presc...

  13. Field emission from crystalline niobium

    Directory of Open Access Journals (Sweden)

    Arti Dangwal Pandey

    2009-02-01

    Full Text Available Appreciable suppression of field emission (FE from metallic surfaces has been achieved by the use of improved surface cleaning techniques. In order to understand the effects of surface preparation on field emission, systematic measurements were performed on five single crystal and three large grain samples of high purity (RRR>300 niobium by means of atomic force microscope, x-ray diffraction, scanning electron microscope (SEM, and dc field emission scanning microscope. The samples were treated with buffered chemical polishing (BCP, half of those for 30  μm and others for 100  μm removal of surface layer, followed by a final high pressure water rinsing. These samples provided the emission at minimum surface fields of 150  MV/m and those with longer BCP treatment showed the onset of field emission at slightly higher fields. A low temperature (∼150°C heat treatment in a high vacuum (10^{-6}  mbar chamber for 14 hours, on a selected large grain Nb sample, gives the evidence for the grain boundary assisted FE at very high fields of 250 and 300  MV/m. Intrinsic field emission measurements on the present Nb surfaces revealed anisotropic values of work function for different orientations. Finally, an interesting correlation between sizes of all investigated emitters derived from SEM images with respect to their respective onset fields has been found, which might facilitate the quality control of superconducting radio-frequency cavities for linear accelerators.

  14. OVOC Emissions and Atmospheric Transformations.

    Science.gov (United States)

    Yokelson, R. J.; Christian, T. J.; Bertschi, I. T.; Ward, D. E.; Field, R. J.; Hobbs, P. V.; Goode, J.; Mason, S.; Susott, R.; Babbitt, R.; Hao, W. M.

    2002-12-01

    We quantified the main emissions from a few vegetation samples and many biomass fires using ground-based, open-path FTIR and airborne, closed-cell FTIR. The two instruments have been rigorously compared to each other and to PTR-MS and canister sampling. OVOC are major emissions from plants. OVOC account for about 70 percent of NMOC from savanna fires (the largest type of biomass burning) and 70-80 percent of NMOC from production and use of domestic biofuels (the second largest type of biomass burning). A table of average biofuel emissions is presented. Data from laboratory and free-burning fires, obtained from Alaska to South Africa, is used to develop equations that predict OVOC emissions from a wide variety of global fires. The impact of OVOC on smoke plume chemistry and the post-emission transformations of OVOC were investigated with two models. Addition of HCHO alone to the simple chemistry used in some global models dramatically reduces NOx lifetime and speeds up O3 formation rates in plumes. A detailed model verifies these effects and shows that OVOC profoundly affect formation of HOx, peroxide, and nitrogen reservoir species. The modeled photochemical transformations of OVOC are diverse, but some key pathways are unknown. We observed rapid production of both O3 and additional OVOC and OH of 1.7E7 in smoke plumes in Alaska and Africa; all reasonably consistent with model predictions. In addition, we found that cloud processing caused large post-emission changes in smoke trace gases including removal of nearly all methanol, a decrease in acetic acid, and a large increase in HCHO. These observations suggest that OVOC could react in cloud droplets and lead to production of modified aerosol. In addition, transport of OVOC by deep convection may be associated with large effects not explained by solubility alone.

  15. Pre-equilibrium (exciton) model and the heavy-ion reactions with cluster emission

    CERN Document Server

    Betak, E

    2015-01-01

    We bring the possibility to include the cluster emission into the statistical pre-equilibrium (exciton) model enlarged for considering also the heavy ion collisions. At this moment, the calculations have been done without treatment of angular momentum variables, but all the approach can be straightforwardly applied to heavy-ion reactions with cluster emission including the angular momentum variables. The direct motivation of this paper is a possibility of producing the superdeformed nuclei, which are easier to be detected in heavy-ion reactions than in those induced by light projectiles (nucleons, deuterons, $\\alpha$-particles).

  16. Development of a low-maintenance measurement approach to continuously estimate methane emissions: A case study.

    Science.gov (United States)

    Riddick, S N; Hancock, B R; Robinson, A D; Connors, S; Davies, S; Allen, G; Pitt, J; Harris, N R P

    2016-12-18

    The chemical breakdown of organic matter in landfills represents a significant source of methane gas (CH4). Current estimates suggest that landfills are responsible for between 3% and 19% of global anthropogenic emissions. The net CH4 emissions resulting from biogeochemical processes and their modulation by microbes in landfills are poorly constrained by imprecise knowledge of environmental constraints. The uncertainty in absolute CH4 emissions from landfills is therefore considerable. This study investigates a new method to estimate the temporal variability of CH4 emissions using meteorological and CH4 concentration measurements downwind of a landfill site in Suffolk, UK from July to September 2014, taking advantage of the statistics that such a measurement approach offers versus shorter-term, but more complex and instantaneously accurate, flux snapshots. Methane emissions were calculated from CH4 concentrations measured 700m from the perimeter of the landfill with observed concentrations ranging from background to 46.4ppm. Using an atmospheric dispersion model, we estimate a mean emission flux of 709μgm-2s-1 over this period, with a maximum value of 6.21mgm-2s-1, reflecting the wide natural variability in biogeochemical and other environmental controls on net site emission. The emissions calculated suggest that meteorological conditions have an influence on the magnitude of CH4 emissions. We also investigate the factors responsible for the large variability observed in the estimated CH4 emissions, and suggest that the largest component arises from uncertainty in the spatial distribution of CH4 emissions within the landfill area. The results determined using the low-maintenance approach discussed in this paper suggest that a network of cheaper, less precise CH4 sensors could be used to measure a continuous CH4 emission time series from a landfill site, something that is not practical using far-field approaches such as tracer release methods. Even though there are

  17. Transportable Emissions Testing Laboratory for Alternative Vehicles Emissions Testing

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Nigel

    2012-01-31

    The overall objective of this project was to perform research to quantify and improve the energy efficiency and the exhaust emissions reduction from advanced technology vehicles using clean, renewable and alternative fuels. Advanced vehicle and alternative fuel fleets were to be identified, and selected vehicles characterized for emissions and efficiency. Target vehicles were to include transit buses, school buses, vocational trucks, delivery trucks, and tractor-trailers. Gaseous species measured were to include carbon monoxide, carbon dioxide, oxides of nitrogen, hydrocarbons, and particulate matter. An objective was to characterize particulate matter more deeply than by mass. Accurate characterization of efficiency and emissions was to be accomplished using a state-of-the-art portable emissions measurement system and an accompanying chassis dynamometer available at West Virginia University. These two units, combined, are termed the Transportable Laboratory. An objective was to load the vehicles in a real-world fashion, using coast down data to establish rolling resistance and wind drag, and to apply the coast down data to the dynamometer control. Test schedules created from actual vehicle operation were to be employed, and a specific objective of the research was to assess the effect of choosing a test schedule which the subject vehicle either cannot follow or can substantially outperform. In addition the vehicle loading objective was to be met better with an improved flywheel system.

  18. A metamaterial for directive emission.

    Science.gov (United States)

    Enoch, Stefan; Tayeb, Gérard; Sabouroux, Pierre; Guérin, Nicolas; Vincent, Patrick

    2002-11-18

    In this paper we present the first results on emission in metamaterial. We show how the specific properties of metallic composite material can modify the emission of an embedded source. We show that under proper conditions the energy radiated by a source embedded in a slab of metamaterial will be concentrated in a narrow cone in the surrounding media. An experimental demonstration of this effect is given in the microwave domain, and the constructed antenna has a directivity equivalent to the best reported results with photonic-crystal-based antennas but using a completely different physical principle [B. Temelkuaran, J. Appl. Phys. 87, 603 (2000)

  19. Sonification of acoustic emission data

    Science.gov (United States)

    Raith, Manuel; Große, Christian

    2014-05-01

    While loading different specimens, acoustic emissions appear due to micro crack formation or friction of already existing crack edges. These acoustic emissions can be recorded using suitable ultrasonic transducers and transient recorders. The analysis of acoustic emissions can be used to investigate the mechanical behavior of different specimens under load. Our working group has undertaken several experiments, monitored with acoustic emission techniques. Different materials such as natural stone, concrete, wood, steel, carbon composites and bone were investigated. Also the experimental setup has been varied. Fire-spalling experiments on ultrahigh performance concrete and pullout experiments on bonded anchors have been carried out. Furthermore uniaxial compression tests on natural stone and animal bone had been conducted. The analysis tools include not only the counting of events but the analysis of full waveforms. Powerful localization algorithms and automatic onset picking techniques (based on Akaikes Information Criterion) were established to handle the huge amount of data. Up to several thousand events were recorded during experiments of a few minutes. More sophisticated techniques like moment tensor inversion have been established on this relatively small scale as well. Problems are related to the amount of data but also to signal-to-noise quality, boundary conditions (reflections) sensor characteristics and unknown and changing Greens functions of the media. Some of the acoustic emissions recorded during these experiments had been transferred into audio range. The transformation into the audio range was done using Matlab. It is the aim of the sonification to establish a tool that is on one hand able to help controlling the experiment in-situ and probably adjust the load parameters according to the number and intensity of the acoustic emissions. On the other hand sonification can help to improve the understanding of acoustic emission techniques for training

  20. The H-alpha Variations of the Luminous Blue Variable P Cygni: Discrete Absorption Components and the Short S Doradus Phase

    OpenAIRE

    Richardson, Noel D.; Morrison, Nancy D.; Gies, Douglas R.; Markova, N; Hesselbach, Erica N.; Percy, J. R.

    2011-01-01

    P Cygni is a prototype of the Luminous Blue Variables (or S Doradus variables), and the star displays photometric and emission line variability on a timescale of years (known as the "short S Doradus phase" variations). Here we present new high resolution H-alpha spectroscopy of P Cyg that we combine with earlier spectra and concurrent V-band photometry to document the emission and continuum flux variations over a 24 y time span. We show that the emission and continuum fluxes vary in concert o...