Tesis sobre el tema "Aeronautic emissions"
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Eastham, Sebastian D. (Sebastian David). "Human health impacts of high altitude emissions". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98585.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 132-159).
Millions of deaths worldwide are attributed annually to exposure degraded surface air quality and UV-induced skin cancer. However, the focus has been on surface emissions, and the contribution of high altitude emissions to these issues is rarely examined. In this thesis, potential links are investigated between high altitude emissions and damages or benefits to human health via photochemical effects. Changes in population exposure to fine particulate matter, ozone and UV-B radiation resulting from current and future high altitude emissions are calculated, applying epidemiologically-derived impact functions to estimate resultant mortality and morbidity. A stratospheric extension is developed for the widely-used tropospheric model GEOS-Chem, which has been shown to accurately model tropospheric conditions and used in simulations of remote and urban pollution. This extended model, the GEOS-Chem UCX, can propagate a stratospheric perturbation through to a tropospheric impact, including shortwave UV fluxes, long-lived species, stratospheric water chemistry and high altitude aerosols. This model is employed to estimate the impacts of reversing 1 K of global warming using stratospheric sulfate aerosol injection. In total, it is projected that 85,000 additional premature mortalities would occur in 2040 due to particulate matter exposure, but that reduced ozone loading would prevent 64,000 mortalities worldwide. Aerosol injection also results in a 5.7% reduction in the global ozone column and a 3.0% increase in surface UV-B, which could cause 3,700 additional melanoma mortalities per year. By comparison, surface air quality and UV-B impacts due to aviation emissions are found to have resulted in 16,000 premature mortalities globally in 2006, of which 450 occurred in North America. Ozone exposure contributes 43% of this total. The increase in tropospheric ozone due to aviation emissions is found to have prevented 390 skin cancer mortalities in 2006. This thesis quantifies the photochemical mechanisms connecting future and proposed high altitude emissions schemes to human health impacts and provides an estimate of mortality and morbidity attributable to aviation and sulfate aerosol injection.
by Sebastian D. Eastham.
Ph. D.
Prashanth, Prakash. "Post-combustion emissions control for aero-gas turbine engines". Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/122402.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-50).
Aviation NO[subscript x] emissions have an impact on air quality and climate change, where the latter is magnified due to the higher sensitivity of the upper troposphere and lower stratosphere. In the aviation industry, efforts to increase the efficiency of propulsion systems are giving rise to higher overall pressure ratios which results in higher NO[subscript x] emissions due to increased combustion temperatures. This thesis identifies that the trend towards smaller engine cores (gas generators) that are power dense and contribute little to the thrust output presents new opportunities for emissions control that were previously unthinkable when the core exhaust stream contributed significant thrust. This thesis proposes and assesses selective catalytic reduction (SCR), which is a post-combustion emissions control method used in ground-based sources such as power generation and heavy-duty diesel engines, for use in aero-gas turbines.
The SCR system increases aircraft weight and introduces a pressure drop in the core stream. The effects of these are evaluated using representative engine cycle models provided by a major aero-gas turbine manufacturer. This thesis finds that employing an ammonia-based SCR can achieve close to 95% reduction in NO[subscript x] emissions for ~0.4% increase in block fuel burn. The large size of the catalyst needs to be housed in the body of the aircraft and hence would be suitable for future designs where the engine core is also within the fuselage, such as would be possible with turbo-electric or hybrid-electric designs. The performance of the post-combustion emissions control is shown to improve for smaller core engines in new aircraft in the NASA N+3 time-line (2030-2035), suggesting the potential to further decrease the cost of the ~95% NO[subscript x] reduction to below ~0.4% fuel burn.
Using a global chemistry and transport model (GEOS-Chem) this thesis estimates that using ultra-low sulfur (<15 ppm fuel sulfur content) in tandem with post-combustion emissions control results in a ~92% reduction in annual average population exposure to PM₂.₅ and a ~95% reduction in population exposure to ozone. This averts approximately 93% of the air pollution impact of aviation.
by Prakash Prashanth.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
Allaire, Douglas L. "A physics-based emissions model for aircraft gas turbine combustors". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35584.
Includes bibliographical references (p. 103-105).
In this thesis, a physics-based model of an aircraft gas turbine combustor is developed for predicting NO. and CO emissions. The objective of the model is to predict the emissions of current and potential future gas turbine engines within quantified uncertainty bounds for the purpose of assessing design tradeoffs and interdependencies in a policy-making setting. The approach taken is to capture the physical relationships among operating conditions, combustor design parameters, and pollutant emissions. The model is developed using only high-level combustor design parameters and ideal reactors. The predictive capability of the model is assessed by comparing model estimates of NO, and CO emissions from five different industry combustors to certification data. The model developed in this work correctly captures the physical relationships between engine operating conditions, combustor design parameters, and NO. and CO emissions. The NO. estimates are as good as, or better than, the NO. estimates from an established empirical model; and the CO estimates are within the uncertainty in the certification data at most of the important low power operating conditions.
by Douglas L. Allaire.
S.M.
Jun, Mina. "Microphysical modeling of ultrane hydrocarbon-containing aerosols in aircraft emissions". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67064.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 109-115).
Combustion engines emit precursors of ne particulate matter (PM) into the atmosphere. Numerous gaseous species, soot particles, and liquid aerosols in the aircraft exhaust are involved in PM formation, and these very ne, nanometer-size particles potentially have signicant impacts on climate, human health, and air quality. In particular, the organic content of the particles is important to determine physical and chemical properties of PM and consequently their potential impacts on the environment. The main objective of this thesis is to understand the role of organic compounds in PM evolution by developing a microphysical model that incorporates organic compounds into the formation mechanism of binary aqueous aerosols. While binary aerosol models with sulfuric acid and water have been widely studied, the understanding of the effect of organics on the formation and growth of aerosols is still insufficient. This work demonstrates important interactions and competitions in the formation of multi-component aerosols with organic compounds, sulfuric acid, and water in aircraft emissions. Hydrocarbon-containing aerosols have been identied as a major component of ground-level aircraft emission, especially at low power operations. This thesis describes selected surrogates of organic species and introduces estimation techniques for their thermophysical properties. The surrogates of organic species include water-insoluble hydrocarbons and water-soluble oxygenated hydrocarbons. Simulation results suggest that certain hydrocarbon compounds play an important role in the formation of aviation aerosol with interactions with both homogeneous sulfuric acidwater aerosols and soot particles in the organic-rich aircraft plume. Hydrocarbons contribute to the growth of existing homogeneous liquid particles, whereas their contribution to aerosol number density is negligible compared to that of sulfuric acid and water, which largely determine the formation of homogeneous aerosols. Also, low volatility hydrocarbons (e.g., benzopyrene, coronene) are observed to be partitioned into soot particles and induce competition with the uptake of water-soluble species, while light water-soluble oxygenated hydrocarbons enhance the uptake of water and sulfuric acid on soot particles.
by Mina Jun.
Ph.D.
Dorbian, Christopher S. (Christopher Salvatore). "Estimating the environmental benefits of aviation fuel and emissions reductions". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59668.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 99-103).
With commercial aviation continuing to grow and environmental policymaking activity intensifying, it is becoming increasingly necessary to assess the environmental impact of measures that result in changes in aviation fuel bum levels. For estimating air quality and climate impacts, it is important to employ a multi-gas approach that accounts for the effects of all emitted species, not just carbon dioxide (CO₂). The main objective of this thesis is to develop a simplified framework for monetizing the CO₂ and non-CO₂ co-benefits of aviation fuel and emissions reductions. The approach is based on two main pieces, both of which are derived using the Aviation environmental Portfolio Management Tool (APMT). First, the air quality marginal damage cost of a unit of fuel is estimated using an air quality response surface model. Second, a simplified probabilistic impulse response function model for climate is employed to derive a non-CO₂/CO₂ impact ratio that can be multiplied by a social cost of carbon to estimate the additional benefits of fuel bum reductions from aviation beyond those associated with CO2 alone. The sensitivity of the non-CO₂/CO₂ climate ratio to metric choice, scientific assumptions, background scenarios, and other policymaker choices is explored. Notably, it is found that given the large uncertainties in short-lived effects, the choice of metric is not particularly influential on the overall ratio value (that is, similar results-within the range of uncertainty-are found for the different metrics considered). This thesis also validates the use of the climate ratios and air quality marginal damages through two sample applications. The first study explores the impact of various aviation growth scenarios and demonstrates the applicability of this framework to a multi-year analysis. The second study concerns the introduction of an advanced aircraft concept into the present-day aviation fleet and demonstrates the ability of the climate ratios to capture scientific and valuation-based uncertainties. In both cases, the derived ratios and air quality damage costs are found to be a good surrogate for a full impact analysis in APMT, relative to the overall uncertainty in estimating impacts.
by Christopher S. Dorbian.
S.M.
Lee, Joosung Joseph 1974. "Historical and future trends in aircraft performance, cost, and emissions". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8825.
Includes bibliographical references (p. 141-144).
Air travel is continuing to experience the fastest growth among all modes of transport. Increasing total fuel consumption and the potential impacts of aircraft engine emissions on the global atmosphere have motivated the industry, scientific community, and international governments to seek various emissions reduction options. Despite the efforts to understand and mitigate the impacts of aviation emissions, it still remains uncertain whether proposed emissions reduction options are technologically and financially feasible. This thesis is the first of its kind to analyze the relationship between aircraft performance and cost, and assess aviation emissions reduction potential based on analytical and statistical models founded on a database of historical data. Technological and operational influences on aircraft fuel efficiency were first quantified utilizing the Breguet range equation. An aviation system efficiency parameter was defined, which accounts for fuel efficiency and load factor. This parameter was then correlated with direct operating cost through multivariable statistical analysis. Finally, the influence of direct operating cost on aircraft price was statistically determined. By comparing extrapolations of historical trends in aircraft technology and operations with future projections in the open literature, the fuel burn reduction potential for future aircraft systems was estimated. The economic characteristics of future aircraft systems were then determined by utilizing the technology-cost relationship developed in the thesis. Although overall system efficiency is expected to improve at a rate of 1.7% per year, it is not sufficient to counter the projected annual 4 to 6% growth in demand for air transport. Therefore, the impacts of aviation emissions on the global atmosphere are expected to continue to grow. Various policy options for aviation emissions reduction and their potential effectiveness are also discussed.
by Joosung Loseph Lee.
S.M.
Lee, Joosung Joseph 1974. "Modeling aviation's global emissions, uncertainty analysis, and applications to policy". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/28917.
Includes bibliographical references (p. 131-134).
(cont.) fuel burn results below 3000 ft. For emissions, the emissions indices were the most influential uncertainties for the variance in model outputs. By employing the model, this thesis examined three policy options for mitigating aviation emissions. More stringent engine certification standards, continuous descent approach procedures, and derated take-off procedures were analyzed. Uncertainties of the model were carefully accounted for in the fuel burn and emissions scenarios of the policy options. The considered policy options achieved roughly 10-30% reductions in NOx emissions. However, HC and CO emissions rather increased due to higher emissions production rate for the CDA and derated take-off. In addition, the NOx emissions reductions in some cases were not statistically significant given the uncertainty in the modeling tool.
Air travel continues to experience fast growth. Although the energy intensity of the air transport system continues to improve, aviation fuel use and emissions of many pollutants have risen. This thesis focuses on developing, assessing and applying a system model to evaluate global aircraft fuel consumption and emissions, and to examine technological and operational measures to mitigate these emissions. The model is capable of computing how much emissions are produced on a flight-by-flight, fleet and global basis and where in the atmosphere the emissions are deposited. These are important questions for aviation environmental policy-making. Model development was followed by a comprehensive uncertainty analysis. It involved comparisons of reported versus modeled results at both the modular and system levels. On average, the aggregate-level composite fuel burn results showed about -6% difference from reported fuel burn data. A statistical analysis showed that this mean shift was a combined contribution of the key uncertainties in aircraft performance and operations. A parametric study followed to rank-order the effects that the key modeling uncertainties had on estimates of fuel burn and emissions. Statistical methods were developed to analyze both the random and systematic errors of the modeling tools. The analyses showed that the uncertainties in engine and aerodynamic performance had the largest impact on system errors, accounting for around 60-70% of the total variance in full-mission fuel burn results. The uncertainties in winds aloft and take-off weight explained another 20-25%. LTO procedures, which consist of engine throttle setting, rate of climb/descent and flight speed, were the most influential uncertainties that drove the variance in
by Joosung Joseph Lee.
Ph.D.
Dedoussi, Irene Constantina. "Adjoint sensitivity analysis of the atmospheric impacts of combustion emissions". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120414.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 127-149).
Combustion emissions impact the environment through chemical and transport processes that span varying temporal and spatial scales. Numerical simulation of the effects of combustion emissions and potential corresponding mitigation approaches is computationally expensive. Atmospheric adjoint modeling enables the calculation of receptor-oriented sensitivities of environmental metrics of interest to emissions, overcoming the numerical cost of conventional modeling. This thesis applies and further develops an existing adjoint of a chemistry-transport model to perform three evaluations, where the high number of inputs (due to the nature of the problem or the associated uncertainty) prevented comprehensive assessment in the past. First, this thesis quantifies the pollution exchange between the US states for seven major anthropogenic combustion emissions sectors: electric power generation, industry, commercial/residential, aviation, as well as road, marine, and rail transportation. This thesis presents the state-level fine particulate matter (PM₂.₅) early death impacts of combustion emissions in the US for 2005, 2011 and 2018 (forecast), and how these are driven by sector, chemical species, and location of emission. Results indicate major shifts in the chemical species and sectors that cause most early deaths, and opportunities for further improving air quality in the US. Second, this thesis quantifies how changes in emissions impact the marginal atmospheric PM₂.₅ response to emissions perturbations. State-level annual adjoint sensitivities of PM₂.₅ population exposure to precursor emissions are compared for the years of 2006 and 2011, and correlated with the magnitude of emissions reduction and the background ammonia mixing ratio. Third, this thesis presents the development and evaluation of the discrete adjoint of the GEOS-Chem unified tropospheric-stratospheric chemistry extension (UCX), which enables the calculation of stratospheric sensitivities and the examination of the entire design space of high altitude emissions impacts. To illustrate its potential, sensitivities of stratospheric ozone to precursor species are calculated. This development expands the span of atmospheric chemistry-transport questions (including inversions) that this open-source model can be used to answer. The assessments performed in this thesis span spatial scales from the regional to the global and demonstrate the ability of this approach to provide information on both bottom-up and top-down mitigation approaches.
by Irene Constantina Dedoussi.
Ph. D.
Galligan, Timothy R. "CO₂ emissions reduction potential of aviation biofuels in the US". Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/122397.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 55-60).
Aviation biofuels derived from biomass and wastes have been identified as a means to reduce carbon dioxide (CO₂) emissions from US aviation, but the magnitude of the possible reduction has not been quantified. This scenario-based analysis quantifies the life cycle greenhouse gas (GHG) mitigation potential of aviation biofuels in 2050 within the US. Projected arable land availability, growth in agricultural yields, and the availability of wastes and residues are estimated as a function of future economic and climate patterns, and variability is accounted for. Under a baseline set of assumptions, the use of aviation biofuels results in a maximum reduction of 163 Tg of CO₂ equivalent (CO₂e) in 2050, a 42% reduction in life cycle GHG emissions compared to petroleum-derived jet fuel. Across all scenarios assessed, the reduction in life cycle GHGs ranges from 47.0 to 207 Tg CO₂e (12-53%), requiring the use of fuels derived from wastes, agriculture and forestry residues, and cultivated energy crops. Using only fuels derived from residues and wastes, up to 35% of US jet fuel demand could be met, corresponding to a 28% reduction of CO₂e. The results are most sensitive to assumptions on the distribution of fuel products, and agricultural residue availability.
by Timothy R. Galligan.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
Gill, Simaranjit Singh. "Controlling diesel NO_x & PM emissions using fuel components and enhanced aftertreatment techniques : developing the next generation emission control system". Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3643/.
Ashok, Akshay. "The air quality impact of aviation in future-year emissions scenarios". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68168.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 104-112).
The rapid growth of aviation is critical to the world and US economy, and it faces several important challenges among which lie the environmental impacts of aviation on noise, climate and air quality. The first objective of this thesis addresses the requirements of section 753 of the US Energy Policy Act, and entails the quantification of present and future-year regional air quality impacts of US Landing and Take-Off (LTO) aviation emissions. In addition, this thesis characterizes the sensitivity of these impacts to variations in the projection of non-aviation anthropogenic emissions (referred to as background emissions). Finally, the implication of a future-year background emissions scenario on the current policy analysis tool, the response surface model (RSMv2), is discussed. Aviation emissions for 2006 are generated using the Aviation Environmental Design Tool (AEDT), while future-year aviation emissions are developed for 2020 and 2030 using the Federal Aviation Administration (FAA) Terminal Area Forecast (TAF) and the International Civil Aviation Organization (ICAO) Committee on Aviation Environmental Protection (CAEP/8) NOx Stringency scenario #6. Background emissions for the year 2005 and 2025 are generated from the US Environmental Protection Agency (EPA) National Emissions Inventory (NEI), and two additional sensitivity scenarios are derived from the emissions forecasts. Uncertainties in present and forecast aviation and background emissions are also characterized. The Community Multiscale Air Quality (CMAQ) model is evaluated to quantify its performance in predicting ambient PM2.5 and ozone concentrations, and it is used to estimate aviation air quality impacts of aviation. Future-year aviation particulate matter (PM2.5) concentrations are found to increase by a factor of 2 and 2.4 by 2020 and 2030, and are dominated by nitrate and ammonium PM. Aviation 8-hour daily maximum ozone is seen to grow by a factor of 1.9 and 2.2 by 2020 and 2030, with non-homogeneous spatial impacts. Aviation PM2.5 varies by +/-25% with a +/-50% variation of the forecast change in background emissions, while changes in ozone impacts are less symmetric at +34%/-21%. The RSMv2 is shown to under-predict future-year aviation nitrate and ammonium PM2.5. Finally, the implications of these results on the aviation industry and on aviation policy are discussed.
by Akshay Ashok.
S.M.
King, Daniel J. S. M. Massachusetts Institute of Technology. "Conceptual aircraft design for environmental impact : modeling operations for emissions assessment". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34138.
Includes bibliographical references (p. 121-123).
Decisions that guide technology investment and policy-making for the future of air transportation will be based in part on the tradeoffs between environmental performance and economics. The Environmental Design Space (EDS) project explores the tradeoffs between noise, emissions, and economics for conceptual design of future aircraft. A key component to EDS is modeling the emissions of aircraft in operation. Traditional design tools need more detailed mission analysis to calculate operational emissions in the landing and takeoff cycle (LTO), and in cruise. This thesis presents a methodology for modeling an aircraft flight profile and the corresponding aircraft and engine states required to calculate emissions over that mission. The methodology was implemented as an operations model in EDS. The development of the methodology and demonstrations of the model are presented in this thesis. The model takes user-input flight procedures, including mission range, and uses aerodynamic models and engine models from EDS to calculate flight profiles. The operations model can be used for analyzing the relationships between flight procedures, and emissions and fuel burn for a fixed design. Alternatively, multidisciplinary design optimization (MDO) with EDS and the operations model can be used to optimize the aircraft design for minimized emissions in the flight profile.
(cont.) MDO with the new model enables exploration of a design space that includes operations along with design in evaluating tradeoffs between emissions, noise, and economics. In addition to the development and demonstration of the operations model, a detailed study of the effects of derated-thrust takeoffs on emissions and fuel burn for Boeing 777 flights is presented in this thesis. The emissions of airline flights are calculated from flight data and compared to International Civil Aviation Organization (ICAO) assumptions for the engines used. The results show that NOx emissions are significantly less than the ICAO assumed values for takeoff and climb-out. A second analysis compares the emissions of derated thrust; takeoffs to the emissions that would have resulted if the same aircraft had flown with full-power on the same day. The results show a relationship between percent derate and a change in the emissions produced in takeoff, and a tradeoff of increased fuel burn for a decrease in NOx production.
by Daniel J. King.
S.M.
Takiguchi, Yu. "Emission of whistler waves from an ionospheric tether". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54621.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 121-122).
In this thesis, we analyze how electromagnetic waves propagate in ionosphere around the earth which is magnetized plasma. We calculate the electromagnetic wave field made by a dipole antenna at an arbitrary observation point far from the antenna using the Stationary Phase Method. With this wave field, wave energy flux is calculated, and by integrating this wave energy flux on the sphere around the antenna, the radiation resistance of this antenna is computed. We compare the results with some past analytical and experimental works. We also analyze the wave propagation characteristics. The wave propagation ways are different for different wave frequencies. We precisely analyze this different wave propagation ways by analyzing the group velocity and k surface of the wave. There are intense radiation directions. We discuss the nature of these intense radiation directions and compare the characteristics with the past works. There are spatial oscillations of wave fields and wave energy flux. We also discuss the reason of this oscillation and compare with the past works.
by Yu Takiguchi.
S.M.
Simone, Nicholas W. (Nicholas William). "Development of a rapid global aircraft emissions estimation tool with uncertainty quantification". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79335.
This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from department-submitted PDF version of thesis.
Includes bibliographical references (p. 44-47).
Aircraft emissions impact the environment by changing the radiative balance of the atmosphere and impact human health by adversely affecting air quality. Many tools used to quantify aircraft emissions are not open source and in most cases are computationally expensive. This limits their usefulness for studies that require rapid simulation, such as uncertainty quantification and assessment of many policy options. We describe the methods used to develop the open source Aviation Emissions Inventory Code (AEIC) and produce a global emissions inventory for the year 2005 from scheduled civil aviation, with quantified uncertainty. This is the most up-to-date openly available inventory for use in atmospheric modeling studies. We estimate that in 2005, scheduled civil aviation was responsible for 180.6 Tg (90% CI: 136.1-232.9 Tg) of fuel burn, equating to 155.5 Tg of CO2 as C (90% CI: 117.3-200.7 Tg) and 0.108 Tg of SOx as S (90% CI: 0.080-0.142 Tg) emissions. 2.689 Tg of NOx as NO2 (90% CI: 1.761-3.804 Tg), 0.749 Tg of CO (90% CI: 0.422-1.145 Tg), and 0.201 Tg of HC as CH4 (90% CI: 0.072-0.362 Tg) were also emitted. 92% of fuel burn took place in the northern hemisphere. Landing and takeoff operations were responsible for 9.1% of total global fuel burn, while 70.6% of fuel burn occurred above 8 km. Our total fuel burn estimate agrees within 4% of other published emissions inventories for the years 2004 and 2006, which is within the uncertainty range of the analysis.
by Nicholas W. Simone.
S.M.
Mashio, Tomoka 1973. "A study of ground-level air pollutant emissions from airport mobile sources". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80650.
Wong, Lawrence Man Kit. "Climate impact of aviation NOx̳ emissions : radiative forcing, temperature, and temporal heterogeneity". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93802.
In title on title page, double underscored "x" appears as subscript. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-49).
Aviation NOx emissions are byproducts of combustion in the presence of molecular nitrogen. In the upper troposphere, NOx emissions result in the formation of O₃ but also reduce the lifetime of CH4 , causing an indirect reduction in the formation of O₃. Meta studies by Lee et al. and Prather et al. concluded that the short-lived O₃ radiative forcing (RF) was greater than the combined long-lived CH₄ and O₃ RFs, leading to a net positive RF (4.5 to 14.3 mW/m² per Tg of NOx emissions). However, few simulations assess the surface air temperature (SAT) response, or conduct a large ensemble simulation with climate feedback in the cases where SAT is predicted. We aim to quantify the climate forcing and temperature response of aviation NOx emissions. Eight 400-member ensemble simulations are conducted with an earth system model of intermediate complexity. Inter-scenario comparisons between emissions starting in 1991, 2016 and 2036 with mid-range and high anthropogenic emissions are performed. We then determine the existence of long-term temporal heterogeneity of climate forcing and impact. The global net RF of an aviation NO, emissions inventory is positive from 1991 to 2100 while leading to a global average SAT responses of -0.068 K in 2100. Despite the positive zonal RF in the Northern Hemisphere of up to 413.9 mW/m² at 45°N, all latitudes experience cooling after 2075. In another scenario, constant aviation NOx emissions at 4.1 Tg/year cause a global net RF of near zero while leading to a SAT response of -0.020 K in 2100. The unexpected temperature behavior in both scenarios is attributed to the forcing from CH₄ destruction being 64% more effective in generating a SAT response than the O₃ forcing. Despite the positive net RF, the probability of aviation NOx emissions being cooling is 67% because of the relative difference in O₃ and CH₄ efficacies.
by Lawrence Man Kit Wong.
S.M.
Martini, Bastien. "Development and assessment of a soot emissions model for aircraft gas turbine engines". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45256.
Includes bibliographical references.
Assessing candidate policies designed to address the impact of aviation on the environment requires a simplified method to estimate pollutant emissions for current and future aircraft gas turbine engines under different design and operating assumptions. A method for NOx and CO emissions was developed in a previous research effort. This thesis focuses on the addition of a soot mechanism to the existing model. The goal is to estimate soot emissions of existing gas turbine engines within soot measurement uncertainties, and then to use the method to estimate the performance of potential future engines. Soot is non-volatile primary particulate matter. In gas turbine engines the size rarely exceeds l [mu]m. The soot is composed almost exclusively of black carbon, is an aggregate of nearly spherical carbon primary particles, and exhibits fractal behavior. Results of other studies regarding soot nucleation, growth, oxidation, and coagulation rates are integrated within a network of perfectly-stirred reactors and shown to capture the typical evolution of soot inside a gas turbine combustor, with soot formed in the early parts of the combustor and then oxidized. The soot model shows promising results as its emissions estimates are within the measurement uncertainties. Nevertheless, model uncertainties are high. They are the consequence of the large sensitivity to input variables. Therefore, the validity of the model is limited to cases with available engine data. More engine data are needed to develop and assess the soot model.
by Bastien Martini.
S.M.
Matlock, Taylor Scott. "Emission spectroscopy for the study of electric propulsion plasmas". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51634.
Includes bibliographical references (leaves 121-124).
Typical electric propulsion devices rely on the acceleration of highly ionized plasmas to produce thrust at specific impulses unattainable with state-of-the-art chemical systems. This thesis examines the use of a miniaturized Helicon plasma source for an open-ended, electrode-less, cathode-less thruster through emission spectroscopy. The use of non-invasive diagnostics allows the measurement of important plasma parameters near the ionization region, where the plasma densities and temperatures are prohibitively high for typical electrostatic probes, while avoiding the inherent perturbations caused by invasive techniques. A spectral study of the Helicon antenna region, yielding axially resolved information on the electron temperature and degree of ionization, is discussed. A similar study in the near-field plume is presented, along with Doppler shift measurements, which clearly demonstrate continued acceleration upstream of the thruster exit. The Doppler shift measurements are validated by extending the study to a Hall effect thruster plasma, well characterized in the literature. Ion flux estimates from the downstream portion of the spectroscopic survey are compared with Faraday probe measurements. Possible mechanisms for thrust are presented along with their implications on Helicon thruster design.
by Taylor Scott Matlock.
S.M.
Anger-Kraavi, Annela. "Emissions trading for regulating climate change impacts of aviation : a case study of the European Union Emissions Trading Scheme". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610211.
Celik, Murat. "Experimental and computational studies of electric thruster plasma radiation emission". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40306.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 231-239).
Electric thrusters are being developed for in-space propulsion needs of spacecraft as their higher specific impulse enables a significant reduction in the required propellant mass and allows longer duration missions. Over the last few decades many different electric propulsion concepts have been proposed and studied. In studying the electric thrusters, in order to improve the thruster performance as well as to understand the underlying physics of thruster's operation, various diagnostics methods were employed. As one unique method, emission spectroscopy provides a non-invasive, fast and economical diagnostic allowing also the ability to access hard to reach locations. In this study, emission spectroscopy is employed as a means to determine the trends in thruster operations as well as diagnosing the plasma parameters. This study presents the spectral measurement results of three different electric thrusters and plasma sources. First, the BHT-200 Hall thruster emission spectra measurements are presented for varying discharge voltage and for various regions of observation.
(cont.) Second, spectral measurements of a TAL type laboratory mini-Hall thruster, MHT-9, were presented. Third, radiation emission measurements of an experimental Helicon plasma source being studied to assess the possibility of using Helicon discharge as a propulsive system are presented and the trends are discussed. Two collisional-radiative (C-R) models are developed for Argon and Xenon plasmas to analyze the experimental spectra. In the C-R models, electron induced excitation, deexcitation and ionization collisions, and spontaneous radiative de-excitation transitions are simulated for neutral and singly charged ion species. The models are validated against measured spectra obtained using different experimental setups. The BHT-200 Hall thruster has insulator ceramic annular walls made of Boron-Nitride (BN). Erosion of ceramic walls is one of the major life limiting factors for Hall thrusters. Emission spectroscopy is used as a means to determine the trends in the thruster wall erosion rate by measuring the radiation emission of the Boron neutral 249.68nm and 249.77nm lines. Discussion about the spectral measurements and relevant analysis are presented.
by Murat Çelik.
Ph.D.
Sequeira, Christopher J. "An assessment of the health implications of aviation emissions regulations". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43084.
Includes bibliographical references (p. 121-129).
An exploration of the health implications of aviation emissions regulations is made by assessing the results of a study of aviation's effects on United States air quality mandated by the Energy Policy Act of 2005. The Energy Policy Act study results estimated that aviation is responsible for 160 yearly incidences (with a 90% confidence interval of 64 to 270 incidences) of premature mortality of adults age 30 and over ($882 million in year 2001 dollars, with a 91% CI of $196 to $1830 million) due to exposure to particulate matter below 2.5 /im in size (PM2.5) in the continental U.S. as reported by the Environmental Benefits Mapping and Analysis Program (BenMAP). Strong regional differences were noted; for instance, 18% of the total health incidences and costs occurred in Los Angeles County. Aviation was estimated to decrease ozone concentrations, causing small premature mortality disbenefits (health effects avoided due to the presence of aviation) of approximately 2 yearly premature mortality incidences ($9 million). Primary particulate matter values in the Energy Policy Act study's emissions inventory had been generated using a conservatively biased version of the First Order Approximation method version 3.0 (FOA3), known as FOA3a, and the emissions of sulfur oxides (SOx) had been incorrectly computed (underestimated by approximately 15%). To quantify the effects of these differences on health impacts, a comparison was made with a second inventory generated by CSSI, Inc. using FOA3. Based on the comparison, it is estimated that aviation was responsible for 140 to 160 yearly incidences of premature mortality from exposure to PM. 46% to 69% of the incidences were estimated to be due to changes in concentrations of ammonium sulfate secondary PM from SOx, while ammonium nitrate secondary PM was estimated to be responsible for 18% to 20%.
(cont.) Concentrations of volatile primary PM from organic compounds and nonvolatile primary PM were responsible for 6% - 18% and 5% - 14% of the impact, respectively, while volatile primary PM from sulfates was responsible for 0% to 4%. Confidence intervals were not computed, and only the effects of changes in PM concentrations were assessed. Based on the results, it is determined that changing regulations governing nitrogen oxide (NOx) emissions and fuel sulfur content may be effective strategies to mitigate incidences of premature mortality due to aviation. An assessment was made of the effects of changing fuel sulfur concentration from 600 parts per million (ppm), as is typical of current jet fuel, to 15 ppm across the continental U.S. It is estimated that this change would reduce yearly premature mortality incidences due to aviation-related ambient PM exposure by 38%. Confidence intervals were not computed. The cumulative additional costs to refineries to produce 15-ppm fuel could be approximately $260 million, suggesting that the benefits may be comparable to the costs. However, such a strategy could have climate warming impacts since aviation sulfur emissions have a cooling influence on climate. It is also estimated that an immediate deployment of ultra-low sulfur fuel only for takeoffs from Los Angeles County could reduce aviation-related nationwide yearly incidences of mortality by 10%, with Los Angeles County health impacts bring reduced by a factor of 2. The additional costs to refineries may be approximately $12 million, suggesting that such a policy may be cost-beneficial. Finally, a brief exploration is done of a NOx stringency assessment by the International Civil Aviation Organization's Forecasting and Economic Analysis Support Group (FESG), which predicted that an industry-wide investment of $30,000 - $40,000 would be required for every tonne of NOx eliminated if the ICAO NOx standard were to be increased by 10% in the year 2008.
(cont.) FESG found this to be the most cost-effective NO, reduction strategy. A direct comparison with the Energy Policy Act and RSM results is difficult, yet an assessment finds that NO, has health costs of only $2,000 per tonne in both sets of results.
by Christopher J. Sequeira.
S.M.
Kumar, Ravindra. "Modelling motorcycles driving cycles and emissions in Edinburgh". Thesis, Edinburgh Napier University, 2009. http://researchrepository.napier.ac.uk/Output/3047.
Ing, Koh. "Variations in carbon emissions from vehicles at signalised intersections". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/349003/.
Stratton, Russell William. "Life cycle assessment of greenhouse gas emissions and non-CO₂ combustion effects from alternative jet fuels". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59694.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 135-144).
The long-term viability and success of a transportation fuel depends on both economic and environmental sustainability. This thesis focuses specifically on assessing the life cycle greenhouse gas (GHG) emissions and non-CO 2 combustion effects from conventional jet fuel and synthetic paraffinic kerosene (SPK). The research expands upon the work of Wong (2008) by examining Fischer-Tropsch jet fuel from coal and biomass, and hydroprocessed renewable jet (HRJ) fuel from rapeseed, jatropha, algae and salicornia. Each fuel option is a "drop-in" alternative in that they are compatible with existing aviation infrastructure. Using a modified version of the APMT climate impacts module, the additional climate forcing from non-CO 2 combustion effects is combined with the fuel life cycle GHG inventories. Life cycle GHG emissions are only one of many aspects that must be considered when evaluating the feasibility and sustainability of an alternative fuel option. While cost and fresh water availability are important constraints, fuel yield and land requirements for select biomass-based fuel pathways are quantified. This is most important for feedstocks requiring cropland for cultivation. For example, current global production of soy, palm and rapeseed oil translate to only 34%, 43% and 18% of US jet fuel demand, respectively; hence, even small fractions of the petroleum industry translate to massive production scales in absolute terms. By comparison, HRJ from algal oil can yield more than an order of magnitude higher fuel production per hectare of land. Few biofuels were identified with zero life cycle GHG emissions. This contradicts previous studies and likely results from avoiding the displacement method to allocate emissions. Considerable inter and intra fuel option variability was found in life cycle GHG emissions; land use change contributed much to the variability of many pathways. The range in life cycle GHG emissions of all fuel options examined ranged from 0 to 9.1 times those of conventional jet fuel. The uncertainty in treating non-CO 2 combustion effects was found to have a larger influence on the life cycle emissions of each fuel option than the variability of the life cycle GHG inventories; however, including non-CO 2 combustion effects reduced the overall range in emissions of all fuel options considered to only 0 to 4.7 times those of conventional jet fuel. Hence, the inclusion of non-CO 2 effects in the fuel life cycle increases the absolute uncertainty of each fuel option but reduces the overall variability in the life cycle emissions of alternative fuels relative to conventional jet fuel.
by Russell William Stratton.
S.M.
Brunelle-Yeung, Elza. "The impacts of aviation emissions on human health through changes in air quality and UV irradiance". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50606.
Includes bibliographical references (leaves 142-148).
World-wide demand for air transportation is rising steadily. The air transportation network may be limited by aviation's growing environmental impacts. These impacts take the form of climate impacts, noise impacts, and health impacts, the latter of which are addressed in this thesis. Aircraft emissions released into the atmosphere have an impact on human health. In the context of assessing the environmental impacts of aviation-related policies, costs and benefits on human health must be considered. Two different models were developed as tools to assess the impacts of aircraft emissions on human health. The first model estimates the changes in skin cancer incidences and mortalities due to changes in ozone column caused by aircraft NO, emissions. The second model estimates changes in health endpoits related to changes in ambient concentrations of particulate matter (PM25) by estimating changes in elemental carbon, primary and secondary organic PM, secondary sulfates, and secondary nitrates. The air quality model discussed herein is the second iteration in the development of a response surface model (RSM) based on a set of 25 simulations done with the Community Multiscale Air Quality model (CMAQ), a more complex atmospheric chemistry model. The increase in adult premature mortalities in the U.S. caused by air quality impacts of aviation emissions in year 2005 is estimated at 210 deaths per year (90% confidence interval: 130 - 340). This considers only those emissions that occur below 3000 feet above ground level as is consistent with current regulatory practice for aviation.
(cont.) The monetized value of the mortality and morbidity effects using RSM v2 outputs is estimated at $1.4 billion in year 2000 US dollars (90% confidence interval: $550 million - $2.8 billion). Of these total impacts, 4 % are found to stem from emissions of volatile organic compounds and volatile particulate matter from organics, another 12 % from emissions of sulfur dioxide and volatile particulate matter from sulfur, 70 % from nitrogen oxide emissions, and 14% from non-volatile particulate matter emissions The net benefit from subsonic aircraft NOx in year 2002 on nonmelanoma skin cancer incidence and associated mortality in the U.S. is estimated at $130 M (90 % confidence interval : $68 - $220 M) in 2000 dollars. This corresponds to the prevention of approximately 6,200 new basal cell carcinoma cases (BCC) (90 % confidence interval: 3,800 - 9,100), 2,900 new squamous cell carcinoma cases (SCC) (90 % confidence interval: 1,700 - 4,200), and 20 nonmelanoma skin cancer (NMSC) premature mortalities (90 % CI : 13 - 28). The monetary benefits due to the prevention of 20 cases of premature mortality represent 96 % of total skin cancer benefits.
by Elza Brunelle-Yeung.
S.M.
De, Serres Martine. "Environmental policymaking for air transportation : toward an emissions trading system". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112600.
This thesis is an attempt to determine the best possible course of action for the industry. To this end, it begins by assessing contemporary understanding of aviation's impact on the environment, and provides an overview of efforts being made toward reducing aircraft emissions. It then examines various policymaking tools available to best address the issue, concluding with an emissions trading system. Finally, design characteristics of such a system are suggested, and used to provide an analysis of the European attempt to include aviation into its own emissions trading system.
Mouratidis, Theodore. "Aircraft charging using ion emission for lightning strike mitigation : an experimental study". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122708.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 96-97).
Lighting strikes are a problem for aircraft flying in large external electric fields. In most cases, the strike is triggered by the aircraft; as it flies through an electric field, it becomes polarized, and on areas with small radius of curvature, the electric field is magnified. This can result in bidirectional leaders which extend from opposite polarity aircraft extremities. These can connect to oppositely charged regions in a cloud or the ground, resulting in a lightning strike. Current methods to avoid lightning are limited to avoiding thunderstorm regions, as recommended by weather radar or conversations between pilots and the ground. Methods to treat the symptom of a strike have been relatively successful; a mesh placed under the skin of the aircraft can distribute the current and heat of the localized strike. However, there are currently no active measures to prevent the strike from happening.
The Boeing Lightning Strike team at MIT has recently proposed an active system that exploits the physics of how a lightning arc is triggered from an aircraft in flight based on net charge control of the vehicle. The objective of this thesis is to prove the feasibility of controlling the net charge of an aircraft in flight by using ion emission from its surface. Different strategies to control the net charge of a flying isolated body were explored and analyzed. The first strategy tested was based on using charge emission from an electrospray source. A passive flow and forced flow configuration were tested, however it was shown that there were numerous difficulties associated with running the electrosprays in atmospheric pressure. To overcome the limitations of the electrospray source, a second strategy was tested based on a controlled corona discharge, which is known to have increasing current emission with increasing wind speed.
The first experiment was setup in the Wright Brothers Wind Tunnel; sharp tips were used to generate a corona discharge and a metallic sphere was used to simulate the aircraft. Significant electrical potential saturation was observed on the sphere, and it is likely this was due to the filamentary streamer corona regime which produces both positive and negative ions. Thus a new experiment was designed; a thin wire was used to generate a glow corona, which produces predominantly positive ions, and this was attached using GlO (a fiberglass composite material) to a metallically coated airfoil. Charging of much higher magnitudes was observed, indicating the glow corona regime is critically important in optimizing the potential of the airfoil. Charge control of an airfoil (Chord 0.2 m, Span 1 m) at 40 m/s was demonstrated to a level of -42 kV.
For an object of a given characteristic size, a certain amount of charge is required to satisfy the optimal charge condition, where negative and positive leader strikes are both equally likely or unlikely. The achieved potential of -42 kV is the order of magnitude required for this size airfoil based on the theoretical estimates, and these tests also showed a trend of linear potential variation with wind speed.
"Boeing Company for financially supporting my Research Assistantship"
by Theodore Mouratidis.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
Brown, Nicholas M. "Characterisation of emissions and combustion stability of a port fuelled spark ignition engine". Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10821/.
Smith, Wallace D. "Acoustic emission from spectrum fatigue cracks in 7075 aluminum". Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA246391.
Thesis Advisor: Gorman, Michael R. Second Reader: Dutta, Indranath. "December 1990." Description based on title screen as viewed on April 2, 2010. DTIC Identifier(s): Aluminum, fatigue (mechanics), cracking (fracturing), acoustic emissions, wings, fixed wing aircraft, reconnaissance aircraft, flight simulation, 7075 aluminum, theses, naval aircraft, stress waves, crack propagation, acoustic detection, fatigue life, E-2c aircraft, safety factor, mechanical properties. Author(s) subject terms: Includes bibliographical references (p. 69-71). Also available in print.
Simaiakis, Ioannis. "Modeling and control of airport departure processes for emissions reduction". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58289.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 139-141).
Taxiing aircraft contribute significantly to the fuel burn and emissions at airports. This thesis investigates the possibility of reducing fuel burn and emissions from surface operations through a reduction of the taxi times of departing aircraft. Data analysis of the departing traffic in four major US airports provides a comprehensive assessment of the impact of surface congestion on taxi times, fuel burn and emissions. For this analysis two metrics are introduced: one that compares the taxi times to the unimpeded ones and another that evaluates them in terms of their contribution to the airport's throughput. A novel approach is proposed that models the aircraft departure process as a queuing system. The departure taxi (taxi-out) time of an aircraft is represented as a sum of three components: the unimpeded taxi-out time, the time spent in the departure queue, and the congestion delay due to ramp and taxiway interactions. The dependence of the taxi-out time on these factors is analyzed and modeled. The performance of the model is validated through a comparison of its predictions with observed data at Boston's Logan International Airport (BOS). A reduction in taxi times may be achieved through the queue management strategy known as N-Control, which controls the push back process so as to keep the number of departing aircraft on the surface of the airport below a specified threshold. The developed model is used to quantify the impact of N-Control on taxi times, delays, fuel burn and emissions at BOS. Finally, the benefits and implications of N-Control are compared to the ones theoretically achievable from a scheme that controls the takeoff queue of each departing aircraft.
by Ioannis Simaiakis.
S.M.in Technology and Policy
S.M.
Zhang, Jun. "Particle matter emission control and related issues for diesel engines". Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1521/.
Feitosa, Allan Eduardo. "Classification techniques for adaptive distributed networks and aeronautical structures". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-05022019-104746/.
Esta dissertação de mestrado é o resultado de um trabalho colaborativo entre a EMBRAER e a Escola Politécnica da USP no estudo de técnicas de monitoramento do estado de saúde de estruturas (Structural Health Monitoring - SHM) utilizando sensores em estruturas aeronáuticas. O objetivo foi desenvolver técnicas de classificação para discriminar entre diferentes eventos que surgem em estruturas aeronáuticas durante testes; para o curto prazo, aperfeiçoando o atual sistema de SHM utilizado pela EMBRAER, baseado em emissão acústica e, no longo prazo, fomentando o desenvolvimento de um sistema completamente distribuído. Como resultado do estudo de métodos de classificação para uso imediato, desenvolvemos duas técnicas: a Similaridade Espectral e um classificador que utiliza Support Vector Machines (SMV). Ambas as técnicas são soluções não-supervisionadas, devido a natureza não rotulada dos dados fornecidos. As duas soluções foram entregues como um produto final para a EMBRAER para pronta utilização em seu atual sistema de SHM. Ao estudar soluções completamente distribuídas para futuras implementações, desenvolvemos um algoritmo de detecção baseado em técnicas adaptativas. O principal resultado foi uma inicialização especial para um detector de máxima verossimilhança (maximum likelihood - ML) que possui uma taxa de decaimento exponencial na probabilidade de erro até um valor não nulo em regime estacionário, utilizando estimação adaptativa em uma rede distribuída. Os nós que compõem a rede devem decidir, localmente, entre duas hipóteses concorrentes com relação ao estado do ambiente onde eles estão inseridos, utilizando medidas locais e estimativas compartilhadas vindas de nós vizinhos. O desempenho exponencial não depende do valor do passo de adaptação, se este for suficientemente pequeno. Os resultas referentes a este detector distribuído foram publicados na revista internacional IEEE Signal Processing Letters.
Dedoussi, Irene Constantina. "Air pollution and early deaths in the United States : attribution of PM₂.₅ exposure to emissions species, time, location and sector". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90658.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 35-37).
Combustion emissions constitute the largest source of anthropogenic emissions in the US. They lead to the degradation of air quality and human health, by contributing to the formation of fine particulate matter (PM2 .5 ), which is harmful to human health. Previous work computed the population PM2 .5 exposure and number of early deaths caused by emissions from six major sectors: electric power generation, industry, commercial and residential activities, road transportation, marine transportation and rail transportation. In the present work we go beyond aggregate sectors and now attribute exposure and early deaths to sectors, emissions species, time of emission, and location of emission. This enables determination of the emissions reductions that would have the greatest benefit by sectors, species, time and location. We apply a long-term adjoint sensitivity analysis with population exposure to PM2 .5 in the contiguous US as the objective function, and calculate the four dimensional sensitivities (time and space) of PM2 .5 exposure with respect to each emissions species. Epidemiological evidence is used to relate increased population exposure to premature mortalities. This is the first regional application of the adjoint sensitivity analysis method to characterize long-term air pollution exposure. (A global scale application has been undertaken related to intercontinental pollution.) We find that for the electric power generation sector 75% of the attributable PM2 .5 exposure is due to SO2 emissions, and 80% of the annual impacts are attributed to emissions from April to September. This suggests that burning of low sulfur coal has greatest benefit in the summer. In the road transportation sector, 29% of PM2 .5 exposure is due to NO, emissions and 33% from ammonia (NH3), which is a result of emissions after-treatment technologies. We estimate that the benefit of reducing NH3 emissions from road transportation is ~20 times that of NOx per unit mass. 75% of the road transportation ammonia impacts occur during the months October to March. We rank the states based on their contribution to the overall combustion emissions-attributable PM2 .5 exposure in the US, and calculate that California contributes 12%, Pennsylvania 7% and Ohio 5.8%. We publicly release the sensitivity matrices computed, noting their potential use as a rapid air quality policy assessment tool.
by Irene Constantina Dedoussi.
S.M.
Stahlberg, Martin. "Acoustic monitoring and control system to determine the properties of damping materials". Thesis, Nelson Mandela Metropolitan University, 2012.
Payne, Cadence(Cadence Brea). "Auroral arc detection using a COTS spectral photometer for the Auroral Emission Radio Explorer (AERO) CubeSat Mission". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127084.
Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 83-85).
Auroral phenomena are dynamic in nature: observed events have rich structures that are both spatially and temporally complex, with scientifically interesting features. While optical auroral observations using CCDs or all-sky cameras are common, the aurora also have interesting emission properties at radio frequencies (RF), specifically in low-frequency and high-frequency bands. The Auroral Emission Radio Observer (AERO) is a 6U CubeSat, equipped with a novel electromagnetic Vector Sensor (VS) antenna. The VS will target auroral emission in a measurement band from 100 kHz - 15 MHz, which enables the study of interesting emission types such as Auroral Kilometric Radiation (20 kHz -750 kHz), Medium Frequency Bursts (1.6 MHz - 4.4 MHz) and cyclotron emission (2.8 MHz - 3.0 MHz).
The VS antenna measures 4-meters tip-to-tip once deployed from the CubeSat frame, and expands to form electric dipoles and magnetic loop antennas that are sensitive enough to probe this diverse set of science targets. Having a spacebased platform, such as AERO's vector sensor antenna, positions the detector above the ionospheric plasma frequency which would otherwise limit observations of radio emissions. Novel measurements from AERO's VS antenna require a set of contextual data to validate the fidelity of resulting data products. AERO includes a secondary payload referred to as an Auxiliary Sensor Package (ASP) that will augment VS measurements with contextual optical and magnetic data. The objective of AERO's contextual optical measurement is to detect the presence of auroral emission in multiple spectral bands, namely green-line emission at 557 nm and red-line emission at 630 nm. An AMS AG AS7262 6-channel visual band spectral photometer is selected as the optical sensor.
We present a radiometric model that evaluates the AS7262 sensor's ability to measure target auroral events. We consider a number of different test scenarios, including varying parameters such as auroral source radiance in units of Rayleigh, spacecraft altitude, and others, to fully assess the sensor's ability to detect optical auroral signatures. The mission requirements include a minimum detection of 5 kR for the sensor to satisfy the optical measurement requirement. In our initial assessment, we find that the selected sensor in its current configuration may not be able to meet this requirement. In its current configuration, the sensor may be capable of detecting the presence of auroral events at high levels of intensity, in the over 100 kR range. The model developed in this work indicates that further analysis and possible modification to the front end optic or the sensor itself are needed.
Though the radiometric model presented is tailored for the AS7262 sensor, it is easily adaptable to assess the performance of other auroral imagers. The contextual measurements provided by the ASP will contribute to the success of the AERO CubeSat mission in demonstrating that remote sensing techniques on CubeSat platforms can address unanswered questions about the aurora.
by Cadence Payne.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
Yoder, Tim (Tim Alan). "Development of aircraft fuel burn modeling techniques with applications to global emissions modeling and assessment of the benefits of reduced vertical separation minimums". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39713.
Includes bibliographical references (p. 49-50).
Given the current level of concern over anthropogenic climate change and the role of commercial aviation in this process, the ability to adequately model and quantify fuel burn and emissions on a system wide scale is of high importance. In particular, the ability to adequately assess the ability of operational alternatives within the commercial aviation system to improve system efficiency and reduce environmental impact is essential. Much work has already been done with this end in mind; however, given the high degree of complexity associated with a large system such as this, there is opportunity for improvements in modeling capability. The work presented in this thesis was conducted with this aim, to build additional functionality and fidelity into an established modeling method. The FAA System for assessing Aviation's Global Emissions (SAGE)'is a well established model for the creation of global inventories of aviation fuel use and emissions. There are, however, two aspects of the model which could benefit from improvements in modeling methodology. The first is the way in which the specific fuel consumption (SFC) is calculated. Previous to this study, SFC was calculated through the methods put forward in EUROCONTROL's Base of Aircraft Data (BADA).
(cont.) These methods are based on aircraft type specific coefficients and perform well in the context of global inventories; however, they lack the necessary functional dependence on ambient and operational variables to adequately assess the effects of the small changes often associated with various operational alternatives. An effort was made to assess the functional dependence of SFC on these variables through statistical analysis of a large body of Computerized Flight Recorder Data (CFDR) and to use this as a basis for improving the modeling of SFC in SAGE. The result of this effort was the introduction of a statistically-derived SFC model into SAGE which contained the desired functional dependence on temperature, pressure, Mach number, and thrust, and thereby improved the fidelity with which fuel bum is modeled. This SFC model, as implemented in SAGE, reduced the average absolute error by 21% as compared to the original BADA model. Additional improvement was made with the introduction of weather information into the SAGE model. Previously, the model assumed standard atmospheric conditions and zero wind. An algorithm was devised which processed and incorporated global assimilated weather data from NASA Goddard into the performance calculations within SAGE.
(cont.) It was found the introduction of dynamic weather contributed greatly to the accuracy of SAGE given that the system wide average true airspeed error is 10% when the assumption of zero winds is used. Finally this improved model was used to quantify the benefits of implementing Reduced Vertical Separation Minimums (RVSM) in US airspace in January of 2005. This was accomplished through a comparison of system wide efficiency during representative time periods prior to and following RVSM implementation. The results of this analysis provide insight into not only the benefits of RVSM, but also the effects of these model improvements and the efficacy of the different efficiency metrics used. It was found that RVSM resulted in an increase in fuel efficiency (nm/kg) of 1.81% (± 0.55%) and an increase in NOx efficiency (nm/kg) of 3.14% (± 1.25%). An additional control comparison was made, during these same time periods, of system efficiency over the North Atlantic and Western Europe where RVSM had been implemented several years prior. Using an efficiency metric which normalized for the difference in winds between the two periods it was found that there was indeed no benefit seen in this control study providing support for the US Domestic RVSM results.
by Tim Yoder.
S.M.
Barrellon-Vernay, Rafaël. "Mécanismes de nucléation des particules volatiles dans les émissions des moteurs d'avions et leurs liens avec la composition du carburant". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR059.pdf.
One of the actual concerns of the aviation industry is to reduce fuel consumption and environmental footprint. Indeed, aviation emissions impact air quality in and around airports. As other transport sectors, aviation effluents need to be addressed to reduce greenhouse gases contribution (2% of these emissions are related to air transport worldwide), volatile and non-volatile Particulate Matter (vPM and nvPM) and indirect impact as condensation trails.To reduce these emissions, different approaches have been investigated, in particular the use of Sustainable Aviation Fuels (SAF). Aims of SAF are to decrease the net CO2 emissions and nvPM. However, combustion of these fuels may lead to new pollutants that can react with atmosphere by formation of secondary aerosols. As part of the UNREAL project (Unveiling Nucleation mechanism in aiRcraft Engine exhAust and its Link with fuel composition), the objective of this work was to study the different molecular mechanisms of new particle formation from the exhausts of aircraft engines fed by fuels with different composition, from the standard Jet A-1 to 100 % SAF fuel.The physicochemical characterisation of the particulate emissions from aircraft engines in real conditions is challenging both from the technical and economical point of view. Thus, a mini-CAST burner, suitable for the combustion of aeronautic liquid fuels, has been used as an alternative to obtain emissions comparable to some extent to those from aircraft engines. A decrease in nvPM emissions (number concentration, mass concentration and size distribution) can be observed in correlation with the quantity of aromatic compounds in the fuel. Moreover, the analysis by mass spectrometry revealed a decrease in the relative intensity of PAHs when alternative fuels were employed . Emissions from the burner have been injected, with and without soot filtration, into an atmospheric chamber for ageing (CESAM chamber reproducing atmospheric conditions at ground level - LISA). For all fuels tested formation of vPM by homogeneous nucleation has been observed in the atmospheric chamber in absence of nvPM. This phenomenon is particularly highlighted for fuels with high amounts of sulphur in their compositions. However, in real cases (presence of soot), the formation of vPM is only observed for the fuels containing high amounts of sulphur. The concentration of gaseous precursors formed for other fuels was not enough to produce vPM after being adsorbed on soot surface (heterogeneous nucleation). On-line characterisation techniques were completed by filter sampling and off-line mass spectrometry analysis, highlighting the presence of PAHs, oxygenated hydrocarbons, sulphur and nitrogen compounds. By employing semi-quantitative methods, it was possible to link the relative chemical composition (sulphur and PAH relative intensity) with vPM formation and their repartitions in particulate and gaseous phases
Pottinger, Sabrina. "Investigation of steady state characteristics of hollow cathode internal plasmas using optical emission spectroscopy". Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/345074/.
Estublier, Denis L. "Radiation emission and absorption in a hydrogen plasma of a laser engine". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42161.
In this work, we describe all the possible radiative processes occuring in a low temperature hydrogen plasma. Some of the fundamental concepts involving ionized gases and collision phenomena are presented, and a rigourous approach is used to show that classical mechanics is quite appropriate to our study.
As an application to a laser engine, we investigate the effects of the maximum temperature, the temperature gradient, the stretching of the plasma shape, the engine pressure, and the equivalent sphere radius, on the total emitted power, including absorbing mechanisms through the equation of radiative transfer.
Graphs related to spectral radiative exitances are included, and a complete set of graphs of the total power, permitting interpolations with respect to the above relevant paramaters, are also provided.
Master of Science
Chossière, Guillaume P. (Guillaume Pierre). "Public health impacts of excess NOx̳ emissions from Volkswagen diesel passenger vehicles in Germany". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112416.
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, Technology and Policy Program, 2017.
Cataloged from PDF version of thesis. In title on title page and in the Abstract, double-underscored "x̳" in "NOx̳" appears as subscript.
Includes bibliographical references (pages 57-65).
In September 2015, the Volkswagen Group (VW) admitted the use of "defeat devices" designed to lower emissions measured during VW vehicle testing for regulatory purposes. Globally, 11 million cars sold between 2008 and 2015 are affected, including about 2.6 million in Germany. On-road emissions tests have yielded mean on-road NOx̳, emissions for these cars of 0.85 g.km-¹, over four times the applicable European limit of 0.18 g.km-1 . This thesis estimates the human health impacts and costs associated with excess emissions from VW cars driven in Germany. A distribution of on-road emissions factors is derived from existing measurements and combined with sales data and a vehicle fleet model to estimate total excess NOx̳ emissions. These emissions are distributed on a 25 by 28 km grid covering Europe, using the German Environmental Protection Agency's (UBA) estimate of the spatial distribution of NOx emissions from passenger cars in Germany. I use the GEOS-Chem chemistry-transport model to predict the corresponding increase in population exposure to fine particulate matter and ozone in the European Union, Switzerland, and Norway, and a set of concentration-response functions to estimate mortality outcomes in terms of early deaths and of life-years lost. Integrated over the sales period (2008 - 2015), I estimate median premature mortality impacts from VW excess emissions in Germany to be 1,200 premature deaths in Europe, corresponding to 13,000 life-years lost and 1.9 billion EUR in costs associated with life-years lost. Approximately 60 % of mortality costs occur outside Germany. For the current fleet, I estimate that if on-road emissions for all affected VW vehicles in Germany are reduced to the applicable European emission standard by the end of 2017, this would avert 29,000 life-years lost and 4.1 billion 2015 EUR in health costs (median estimates) relative to a counterfactual case with no recall.
by Guillaume P. Chossière.
S.M.
S.M. in Technology and Policy
Barnard, Paul Werner. "The prediction of the emission spectra of flares and solid propellant rockets". Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16254.
ENGLISH ABSTRACT: It was shown in an earlier study that it is possible to predict the spectral radiance of rocket combustion plumes directly from the propellant composition and motor parameters. Little is published in the open literature on this subject, but the current trend is to use determinative methods like computational fluid dynamics and statistical techniques to simulate wide band radiance based on blackbody temperature assumptions. A limitation of these methods is the fact that they are computationally expensive and rather complex to implement. An alternative modeling approach was used which did not rely on solving all the nonlinearities and complex relationships applicable to a fundamental model. A multilayer perceptron based Neural Network was used to develop a parametric functional mapping between the propellant chemical composition and the motor design and the resulting spectral irradiance measured in a section of the plume. This functional mapping effectively models the relationship between the rocket design and the plume spectral radiance. Two datasets were available for use in this study: Emission spectra from solid propellant rockets and flare emission spectra. In the case of the solid rocket propellants, the input to the network consisted of the chemical composition of the fuels and four motor parameters, with the output of the network consisting of 146 scaled emission spectra points in the waveband from 2-5 microns. The four motor parameters were derived from equations describing the mass flow characteristics of rocket motors. The mass flow through the rocket motor does have an effect on the shape of the plume of combustion gases, which in turn has an effect on the infrared signature of the plume. The characteristics of the mass flow through the nozzle of the rocket motor determine the thermodynamic properties of the combustion process. This then influences the kind of chemical species found in the plume and also at what temperature these species are radiating energy.The resultant function describing the plume signature is: Plume signature f {p T A fuel composition} t , , , , 1 1 = ε It was demonstrated that this approach yielded very useful results. Using only 18 basic variables, the spectra were predicted properly for variations in all these parameters. The model also predicted spectra that agree with the underlying physical situation when changing the composition as a whole. By decreasing the Potassium content for example, the model demonstrated the effect of a flame suppressant on the radiance in this wavelength band by increasing the predicted output. Lowering the temperature, which drives the process of molecular vibration and translation, resulted in the expected lower output across the spectral band. In general, it was shown that only a small section of the large space of 2 propellant classes had to be measured in order to successfully generate a model that could predict emission spectra for other designs in those classes. The same principal was then applied to predicting the infrared spectral emission of a burning flare. The brick type flare considered in this study will ignite and the solid fuel will burn on all surfaces. Since there are no physical parameters influencing the plume as in the case of the rocket nozzles it was required to search for parameters that could influence the flare plume. It was possible to calculate thermodynamic properties for the flare combustion process. These parameters were then reduced to 4 parameters, namely: the oxidant-fuel ratio, equilibrium temperature, the molar mass and the maximum combustion temperature. The input variables for the flares thus consisted of the chemical composition and 4 thermodynamic parameters described above. The network proposed previously was improved and optimised for a minimum number of variables in the system. The optimised network marginally improved on the pevious results (with the same data), but the training time involved was cut substantially. The same approach to the optimization of the network was again followed to determine the optimal network structure for predicting the flare emission spectra. The optimisation involved starting out with the simplest possible network construction and continuouslyincreasing the variables in the system until the solution predicted by the network was satisfactory. Once the structure of the network was determined it was possible to optimise the training algorithms to further improve the solution. In the case of the solid rocket propellant emission data it was felt that it would be important to be able to predict the chemical composition of the fuel and the motor parameters using the infrared emission spectra as input. This was done by simply reversing the optimised network and exchanging the inputs with the outputs. The results obtained from the reversed network accurately predicted the chemical composition and motor parameters on two different test sets. The predicted spectra of some of the solid propellant rocket test sets and flare test sets did not compare well with the expected values. This was due to the fact that these test sets were in a sparsely populated area of the variable space. These outliers are normally removed from training data, but in this case there wasn’t enough data to remove outliers. To obtain an indication of the strength of the correlation between the predicted and measured line spectra two parameters were used to test the correlation between two line spectra. The first parameter is the Pearson product moment of coefficient of correlation and gives an indication of how good the predicted line spectra followed the trend of the measured spectral lines. The second parameter measures the relative distance between a target and predicted spectral point. For both the solid propellants and the flares the correlation values was very close to 1, indicating a very good solution. Values for the two correlation parameters of a test set of the flares were 0.998 and 0.992. In order to verify the model it was necessary to prove that the solution yielded by the model is better than the average of the variable space. Three statistical tests were done consisting of the mean-squared-error test, T-test and Wilcoxon ranksum test. In all three cases the average of the variable space (static model) and the predicted values (Neural Network model) were compared to the measured values. For both the T-test and the Wilcoxon ranksum test the null hypothesis is rejected when t < -tα = 1.645 and then thealternative hypothesis is accepted, which states that the error of the NN model will be smaller than that of the static model. The mean squared error for the static model was 0.102 compared to the 0.0167 of the neural net, for a solid propellant rocket test set. A ttest was done on the same test set, yielding a value of –2.71, which is smaller than – 1.645, indicating that the NN model outperforms the static model. The Z value for this test set is Z = -11.9886, which is a much smaller than –1.645. The results from these statistical tests confirm that neural network is a valid conceptual model and the solutions yielded are unique.
AFRIKAANSE OPSOMMING: In ‘n vroeër studie is bewys hoe dit moontlik is om die spektrale irradiansie van ‘n vuurpyl se verbrandingspluim te voorspel vanaf slegs die dryfmiddelsamestelling en vuurpylmotoreienskappe. In die literatuur is daar min gepubliseer oor hierdie onderwerp. Dit wil voorkom asof meer deterministiese metodes gebruik word om die probleem op te los. Metodes soos CFD simulasies en statistiese analises word tans verkies om wyeband radiansie te voorspel gebaseer op perfekte swart ligaam teorie. ‘n Groot beperking van hierdie metodes is die feit dat die berekeninge kompleks is en baie lank neem om te voltooi. ‘n Alternatiewe benadering is gebruik, wat nie poog om al die nie-liniêre en komplekse verbande uit eerste beginsels op te los nie. ‘n Neurale netwerk is gebruik om ‘n funksionele verband te skep tussen die chemiese samestelling van die dryfmiddel, vuurpylmotor ontwerp en die spektrale irradiansie van die vuurpyl se pluim. Die funksionele verband kan nou effektief die afhanklikheid van die dryfmiddelsamestelling, vuurpylmotor ontwerp en die spektrale uitset modelleer. Twee datastelle was beskikbaar vir analise: Emissie spektra van vaste dryfmiddel vuurpyle en ook van vaste dryfmiddel fakkels. Die invoer tot die neurale netwerk van die vuurpyle het bestaan uit die chemiese samestelling van die dryfmiddel en 4 vuurpylmotor eienskappe. Die uitvoer van die netwerk het weer bestaan uit 146 spektrale irradiansie waardes in die golflengte band van 2-5μm. Die 4 vuurpylmotor eienskappe is afgelei uit massavloei teorie vir vuurpyl motors, aangesien die uitvloei van die produkgasse ‘n invloed op die pluim van die motor sal hê. Die massavloei het weer ‘n effek op die spektrale handtekening van die pluim. Die eienskappe van die massavloei deur die mondstuk van die vuurpylmotor bepaal die termodinamiese eienskappe van die verbrandingsproses. Die invloed op die verbrandingsproses bepaal weer watter tipe produkte gevorm word en by watter temperatuur hulle energie uitstraal. Die gevolg is dat ‘n funksie gedefinieer kan word wat die pluim beskryf.Pluim handtekening = f{, temperatuur, mondstuk keël grootte, vernouings verhouding van mondstuk, dryfmiddelsamestelling} Deur net 18 invoer nodes te gebruik kon die netwerk die irradiansie suksesvol voorspel met ‘n variansie in al die invoer waardes. Deur byvoorbeeld die Kalium inhoud van die dryfmiddel samestelling te verminder het die model die vermindering van ‘n vlam onderdrukker suksesvol nageboots deurdat die irradiansie ‘n hoër uitset gehad het. Die sensitiwiteit van die model is verder getoets deur die temperatuur in die verbrandingskamer te verlaag, met ‘n korrekte laer irradiansie uitset, as gevolg van die feit dat die temperatuur die molekulêre vibrasie en translasie beweging beheer. Dieselfde benadering is gebruik om die model te bou vir die voorspelling van die fakkels se infrarooi irradiansie. Anders as die vuurpylmotors vind die verbranding in die geval van die fakkels in die atmosfeer plaas. Dit was dus ook nodig om na die termodinamiese eienskappe van die fakkel verbranding te kyk. Verskeie parameters is bereken, maar 4 parameters, naamlik die brandstof-suurstof verhouding, temperatuur, molêre massa en die maksimum verbrandingstemperatuur, tesame met die dryfmiddel samestelling kon die irradiansie van die fakkels suskesvol voorspel. Die bestaande netwerk struktuur vir die vuurpylmotors is verbeter en geoptimiseer vir ‘n minimum hoeveelheid veranderlikes in die stelsel. Die geoptimiseerde netwerk het ‘n klein verbetering in die voorspellings getoon, maar die oplei het drasties afgeneem. Dieselfde benadering is gebruik om die optimale netwerk vir die fakkels te bepaal. Optimisering van die netwerk struktuur is bereik deur met die eenvoudigste struktuur te begin en die hoeveelheid veranderlikes te vermeerder totdat ‘n bevredigende oplossing gevind is. Na die struktuur van die netwerk bevestig is, kon die oordragfunksies op die nodes verder geoptimiseer word om die model verder te verbeter. Dit het verder geblyk dat dit moonlik is om die netwerk vir die vuurpylmotors om te draai sodat die irradiansie gebruik word om die dryfmiddel samestelling en motor eienskappe te voorspel. Die netwerk is eenvoudig omgedraai en die insette het die uitsette geword.Die resultate van die omgekeerde netwerk het bevestig dat dit wel moontlik is om die dryfmiddel samestelling en motor eienskappe te voorspel vanaf die irradiansie. Die voorspelde spektra van beide die vuurpylmotors en die fakkels het nie altyd goed gekorreleer met die gemete data nie. Van die spektra kom voor in ‘n lae digtheidsdeel van die veranderlike ruimte. Dit het tot gevolg gehad dat daar nie genoeg data vir opleiding van die netwerk in die omgewing van die toetsdata was nie. Hierdie data is eintlik uitlopers en moet verwyder word van die opleidingsdata, maar daar is alreeds nie genoeg data beskikbaar om die uitlopers te verwyder nie. Dit is nodig om te bepaal hoe goed die voorspelde data vergelyk met die gemete data. Twee parameters is gebruik om te bepaal hoe goed die data korreleer. Die eerste is die “Pearson product moment of coefficient of correlation”, wat ‘n goeie aanduiding gee van hoe goed die voorspelde waardes die gemete waardes se profiel volg. Die tweede parameter meet die relatiewe afstand tussen die teiken en die voorspelde waardes. Vir beide die vuurpylmotors en die fakkels het die toetsstelle ‘n korrelasiewaarde van baie na aan 1 gegee, wat ‘n goeie korrelasie is. Die waardes van die twee parameters vir een van die fakkel toetstelle was onderskeidelik 0.998 en 0.992. Die model is geverifieer deur te bepaal of die model ‘n beter oplossing bied as die gemiddeld van die veranderlike ruimte. Drie statistiese toetse is gedoen: “Mean-squarederror” toets, T-toets en ‘n “Wilcoxon ranksum” toets. In al drie gevalle word die gemiddelde van die veranderlike ruimte (statiese model) en die voorspelde waardes (Neurale netwerk model) teen die gemete waardes getoets. Vir beide die T-toets en die “Wilcoxon ranksum” toets word die nul hipotese verwerp indien t < ta = 1.645 en dan word die alternatiewe hipotese aanvaar, wat bepaal dat die fout van die neurale netwerk model kleiner is as die van die statiese model. Die “mean-squared-error” van die statiese model was 0.102, in vergelyking met 0.0167 van die neurale netwerk model vir ‘n vuurpylmotor toetsstel. ‘n T-toets is gedoen vir dieselfde toetsstel, met ‘n resultaat van-2.71, wat kleiner is as –1.645 en aandui dat die neurale netwerk model weereens beter presteer as die statiese model. Die Z waarde uit die “Wilcoxon ranksum” toets is Z=- 11.9886, wat baie kleiner is as –1.645. Die resultate van die statitiese toetse toon dat die neurale netwerk ‘n geldige model is en die oplossings van die model ook uniek is.
Tesfa, Belachew Chekene. "Investigations into the performance and emission characteristics of a biodiesel fuelled CI engine under steady and transient operating conditions". Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/11072/.
Baslamisli, Ufuk. "Helicopter Turboshaft Engine Ground Preformance With Alternative Fuels". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614098/index.pdf.
Johnson, Donovan Theodore. "The metallic elephant in the room : short range flights, high-speed rail, and the environment". Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3303.
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Sudarshan, Kumar *. "Computational And Experimental Studies On Flameless Combustion Of Gaseous Fuels". Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1131.
Sudarshan, Kumar *. "Computational And Experimental Studies On Flameless Combustion Of Gaseous Fuels". Thesis, 2004. http://hdl.handle.net/2005/1131.