Dissertationen zum Thema „Photoionization of gases Measurement“
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1
Hennessy, Michael Joseph. „Photoionization of gases in the Extreme Ultraviolet“. Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09SM/09smh515.pdf.
2
Mah, Kelly Robert Lim. „Investigations of resonantly enhanced multiphoton ionizations of atomic mercury and potassium“. Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26451.
Annotation:
Two investigations are reported on the application of resonantly enhanced multiphoton ionization (RMPI) to gaseous mixtures of an atomic vapor and a few Torr of argon. Photon fluxes large enough to ionize atoms by RMPI were produced by focussing down the light from a tunable pulsed dye laser. The irradiances generated were of the order of 500MWcm⁻². Ionization was detected by a voltage biased wire electrode that simply collected the photoelectrons either directly or after some gas multiplication. One investigation was the measurement of the dependence of RMPI processes in mercury on the polarization of the incident light for comparisons with theoretical calculations. The processes were four-photon resonant absorptions to either a ¹S₀ or ¹’³D₂ level followed by single photon ionization. Complete photoionization of all atoms excited to the resonant levels is established and the measured polarization dependences are found to agree with the calculated polarization dependence for the resonant excitation step of the RMPI process. Unexplained observations of the distortions in the polarization dependence of the ion yield and the absorption linewidth of the 6d ¹D₂ resonance are discussed. The second investigation was a study of the density dependent electric dipole forbidden two-photon resonant transition ²S → ²P in three-photon RMPI spectra of the Rydberg states of potassium. Stark interactions are shown to be unlikely and too weak. From the characteristics of the spectra, the excitation process is identified as a laser-assisted collision interaction.Science, Faculty of
Physics and Astronomy, Department of
Graduate
3
Alexandridi, Christina-Anastasia. „Attosecond spectroscopy : study of the photoionization dynamics of atomic gases close to resonances“. Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS571/document.
Annotation:
L'interaction des puissantes impulsions laser avec les gaz atomiques et moléculaires entraîne l’émission de flashs exceptionnellement brefs de lumière XUV grâce au processus de génération harmonique d'ordre élevé (GHOE) de la fréquence laser fondamentale. Ce rayonnement ultra-bref, dans la gamme attoseconde (10⁻¹⁸ s), permet des investigations détaillées de la dynamique électronique ultra-rapide dans la matière. Le travail de cette thèse consiste à étudier les délais de photoionisation au voisinage de différents types de résonances, en utilisant la technique Rainbow RABBIT. Il s'agit d'une technique interférométrique à deux couleurs (XUV + IR) qui permet d'accéder au temps nécessaire à l'électron pour s'échapper du potentiel atomique avec une haute résolution. Nous nous intéressons particulièrement à deux cas: i) les résonances auto-ionisantes spectralement étroites (dizaines de meV) et ii) les minima de type Cooper ayant une largeur spectrale de quelques eV. L'effet de ces structures de continuum sur la dynamique d'ionisation correspondante est étudiéThe interaction of intense laser pulses with atomic and molecular gases results in exceptionally short bursts of XUV light, through the process of high-order harmonic generation of the fundamental laser frequency. This ultrashort radiation, in the attosecond (10⁻¹⁸ s) range, allows detailed investigations of ultrafast electron dynamics in matter. The work of this thesis consists in studying the photoionization delays close to different types of resonances, using the Rainbow RABBIT technique. This is a two-color interferometric technique (XUV + IR) that allows access to the time required for the electron to escape the atomic potential with high resolution. We are particularly interested in two cases: i) autoionizing resonances which are spectrally narrow (tens of meV) and ii) Cooper-type minima which have a spectral width of some eV. The effect of these continuum structures on the corresponding ionization dynamics is studied
4
Chatzipetros, Argyrios. „A simple model of above threshold ionization“. Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42087.
5
Drum, S. M. „The remote detection of gases using coherence measurement“. Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293132.
6
Aliwell, Simon Richard. „Measurement of atmospheric trace gases by absorption spectroscopy“. Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388668.
7
Adam, Nor Mariah. „Measurement of aerosol particles in buildings“. Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294520.
8
Panizza, M. P. „Analysis of complex integral photoelectron spectra /“. Title page, contents and introduction only, 1985. http://web4.library.adelaide.edu.au/theses/09SM/09smp193.pdf.
9
Briers, Michael Geoffrey. „Electrochemical transducers for the continuous measurement of blood gases“. Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314888.
10
Mustafa, Merih. „Measurement and calculation of transport properties of polyatomic gases“. Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47198.
11
Birch, K. P. „The precise determination of refractometric parameters for atmospheric gases“. Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382966.
12
Jun, Byung Soon. „Measurement of thermal accommodation coefficients of inert gas mixtures on a surface of stainless steel /“. free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025627.
13
Kozlowski, Wojciech. „Competition between weak quantum measurement and many-body dynamics in ultracold bosonic gases“. Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:8da45dd9-27f9-42b6-8bae-8001d0154966.
Annotation:
Trapping ultracold atoms in optical lattices enabled the study of strongly correlated phenomena in an environment that is far more controllable and tunable than what was possible in condensed matter. Here, we consider coupling these systems to quantised light where the quantum nature of both the optical and matter fields play equally important roles in order to push the boundaries of what is possible in ultracold atomic systems. We show that light can serve as a nondestructive probe of the quantum state of matter. By considering a global measurement we show that it is possible to distinguish a highly delocalised phase like a superfluid from the Bose glass and Mott insulator. We also demonstrate that light scattering reveals not only density correlations, but also matter-field interference. By taking into account the effect of measurement backaction we show that the measurement can efficiently compete with the local atomic dynamics of the quantum gas. This can generate long-range correlations and entanglement which in turn leads to macroscopic multimode oscillations across the whole lattice when the measurement is weak and correlated tunnelling, as well as selective suppression and enhancement of dynamical processes beyond the projective limit of the quantum Zeno effect in the strong measurement regime. We also consider quantum measurement backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution and demonstrate how this can lead to a new class of measurement projections thus extending the measurement postulate for the case of strong competition with the system's own evolution.
14
Stewart, David G. „Thermophysical properties of gases and gas mixtures for critical flow nozzle applications“. Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248763.
15
Gessini, Paolo. „Measurement of the thrust generated by a hollow cathode with noble gases“. Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427398.
16
Fawcett, Beth. „Diode laser cavity ring down spectroscopy for the measurement of trace gases“. Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274627.
17
Stacey, Blake (Blake C. ). „Relation of electron scattering cross-sections to drift measurement in noble gases“. Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32904.
Annotation:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.Includes bibliographical references (leaves 59-62).
We investigate the classic "inverse problem" of extracting collision and scattering cross sections from measurements of electron swarm behavior. A Monte Carlo technique for simulating electron motion through a gas of isotropic scatterers is presented, providing a simplified version of Biagi's MAGBOLTZ algorithm. Using this Monte Carlo software, we examine the thermalization of electron swarms, focusing on their drift velocity and informational entropy, providing justification for a set of analytic expressions for drift measurements which are valid in the hydrodynamic regime. These expressions are then used to estimate the ⁴He scattering cross section, first by a simple grid interpolation and then through a genetic algorithm (GA). This technique demonstrates that the 4He momentum-transfer cross section in the 0-7 eV range is approximately 6.5 [Angstrom]², with a peak near 2 eV, in agreement with literature values. Empirical cross sections are also presented for Xe and He:CH₄(90:10).
by Blake Stacey.
S.B.
18
Jimenez, Erick G. „Experimental apparatus for characterizing the methane-air combustion process“. Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/16775.
19
Narayan, Shankar B. „Measurement of diffusion and adsorption in porous adsorbents“. Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=73968.
20
Zhang, Jie. „Precision measurement of the refractive indices of the atmospheric gases with frequency combs“. kostenfrei, 2008. http://www.opus.ub.uni-erlangen.de/opus/volltexte/2008/978/.
21
Ganesan, Anita Lakshmi. „Quantifying emissions of greenhouse gases from South Asia through a targeted measurement campaign“. Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82307.
Annotation:
Thesis (Ph. D. in Climate Physics and Chemistry)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 161-167).
Methane (CH 4 ), nitrous oxide (N20) and sulfur hexafluoride (SF6) are powerful greenhouse gases with global budgets that are well-known but regional distributions that are not adequately constrained for the purposes of mitigation and policy initiatives. Quantifying emissions using inverse approaches at the national scale requires measurements that specifically target the region of interest. Primarily due to the lack of atmospheric measurements from the region, emissions estimates of these greenhouse gases from India have largely been missing. New in situ measurements of atmospheric mole fractions from a Himalayan station in Darjeeling, India (27.03'N, 88.26'E, 2200 meters above sea level) have been collected from December 2011 for CH4 and March 2012 for N20 and SF6 to February 2013 using high-precision instrumentation that is linked to the Advanced Global Atmospheric Gases Experiment (AGAGE). These measurements comprise the first high-frequency dataset of these gases collected in India and are used for measurement-based assessment of emissions. Several features are identified. In SF6 , the signal associated with Northern Hemispheric background is typically present. CH4 and N20 mole fractions are almost always enhanced over the background, suggesting strong regional sources. Additionally, a diurnal signal resulting from thermally driven winds is seasonally present. A particle dispersion model is used to track 'air histories' of measurements, quantifying the sensitivity of concentrations at Darjeeling to surface emissions. The effect of topography on the derived air histories is investigated to test the robustness of the model in simulating transport in this complex environment. The newly acquired data set is used to investigate the ability of the model to reproduce signals that stem from the mesoscale diurnal winds. The sensitivities of meteorological resolution and particle release height are investigated to better quantify some of the uncertainties associated with this chemical transport model. A Quasi-Newton inverse method is used to estimate emissions at monthly resolution. CH4 , N20 and SF6 emissions from India are found to be 44.3% Tg yr- 1, 825 1045/707 GgN yr- 1 and 221 241/205 kton yr-', respectively. Significant uncertainty reduction is seen on emissions from India during the summer when the monsoon results in high sensitivity over the subcontinent.
by Anita Lakshmi Ganesan.
Ph.D.in Climate Physics and Chemistry
22
Rowan, Linda. „The measurement of the thermal conductivity of gaseous mixture using the transient hot wire technique“. Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252676.
23
Bell, Robert M. „Mass flow and temperature measurements in the flue of a woodburning appliance“. Thesis, This resource online, 1985. http://scholar.lib.vt.edu/theses/available/etd-07212009-040221/.
24
Brunke, Richard R. „Evaluation of nitrogen losses in the form of ammonia from surface applied manure“. Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65379.
25
Crawley, Louise Helen. „Application of Non-Dispersive Infrared (NDIR) Spectroscopy to the Measurement of Atmospheric Trace Gases“. Thesis, University of Canterbury. Chemistry, 2008. http://hdl.handle.net/10092/2160.
Annotation:
Gaseous pollutants have been an environmental concern since 1956, when the first clean air act was established in the United Kingdom. Monitoring of gaseous emissions is a legal requirement in most countries, and this has generated a large demand for inexpensive, portable, and versatile gas analysers for the measurement of gaseous emissions. Many of the current commercial gas analysers have differing advantages and disadvantages, however, high cost is an important factor. Instruments with low detection limits and the ability to measure multiple gases tend to be very expensive, whereas, single gas analysers tend to be much more affordable. A non-dispersive infrared (NDIR) spectrometer, originally developed for a previous M.Sc. project, has been further developed in order to increase the sensitivity and to extend the instrument to the measurement of multiple gases. This type of instrument would be useful for environmental, industrial, and research applications. The instrument was inexpensive to construct when compared with the cost of current commercial gas analysers, is robust, and is partially portable around the laboratory. Infrared radiation from two infrared sources, pass through adjacent sample and reference cells and into corresponding detector cells. A sample comprising the analyte gas is contained in the sample cell, a non-absorbing gas, such as argon, is contained in the reference cell, and pure analyte gas of interest is contained in the detector cells. The two identical detector cells, which follow the reference and sample cells in the infrared optic paths, communicate only through a differential capacitance manometer which accurately measures small pressure differences between the otherwise identical cells. Any trace amount of the analyte gas in the sample cell absorbs radiation, depleting the appropriate infrared frequencies. This results in lower energy incident on the sample detector cell, reducing the infrared induced pressure rise in that detector cell compared to the reference side detector cell. The pressure difference is ii proportional to the concentration of absorbing gas in the sample cell, which is then determined using a calibration graph. Carbon dioxide, methane, and nitrous oxide calibration graphs from 40 ppm to 1000 ppm have been successfully established, and detection limits of 10.33 ppm for CO₂, 8.81 ppm for N₂O and 9.17 ppm for CH₄ were determined. Dried air samples measured using the spectrometer gave an average value of 382 ± 9.6 ppm which can be compared to the latest global atmospheric loading of 382.4 ppm.
26
Angerstein, Jeanette Louise. „A hemispherical acoustic resonator for the measurement of the speed of sound in gases“. Thesis, University College London (University of London), 2000. http://discovery.ucl.ac.uk/1382240/.
Annotation:
A hemispherical acoustic resonator is described which was designed and constructed for the measurement of the speed of sound in gases, at pressures up to 40 MPa and at temperatures in the range from 300 K to 400 K. The hemispherical geometry retains many of the advantages characteristic of the spherical geometry but affords a major advantage at high pressures because one of the transducers may be placed at a position of maximum acoustic density for the radial modes and so loss of signal strength is minimised. A detailed description is given of the resonator and pressure vessel, the thermostat and the various measurement techniques employed. Characterisation of the resonator was achieved using a prototype equatorial plate for which the sound source could be moved over the radius of the cavity. Using the prototype plate, measurements performed in air at room temperature and pressure allowed the transducer configuration to be optimised. Calibration of the resonator was possible by comparison of the values of ula(pj) obtained isothermally in nitrogen with data obtained previously using a spherical resonator. These measurements allowed the resonator's geometry to be characteriseda nd the dependenceo f the radius on temperaturea nd pressuret o be modelled. The semi-empirical model developed using the results of the calibration was tested using measurements obtained in argon; results were obtained simultaneously from the hemispherical resonator and a well-characterised spherical resonator. Measurements on propene together with the results from nitrogen allowed the halfwidths to be modelled and enabled useful information about the loss mechanisms occurring to be extracted from the measured halfwidths. Tetrafluoromethane was subsequently studied and the acoustic virial coefficients and vibrational relaxation times were measured and compared with literature values.
27
Mazzucchi, Gabriel. „Conditional many-body dynamics and quantum control of ultracold fermions and bosons in optical lattices coupled to quantized light“. Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:6c6eddac-41de-476d-851e-6630907965e6.
Annotation:
We study the atom-light interaction in the fully quantum regime, with the focus on off-resonant light scattering into a cavity from ultracold atoms trapped in an optical lattice. Because of the global coupling between the atoms and the light modes, observing the photons leaking from the cavity allows the quantum nondemolition (QND) measurement of quantum correlations of the atomic ensemble, distinguishing between different quantum states. Moreover, the detection of the photons perturbs the quantum state of the atoms via the so-called measurement backaction. This effect constitutes an unusual additional dynamical source in a many-body strongly correlated system and it is able to efficiently compete with its intrinsic short-range dynamics. This competition becomes possible due to the ability to change the spatial profile of a global measurement at a microscopic scale comparable to the lattice period, without the need of single site addressing. We demonstrate nontrivial dynamical effects such as large-scale multimode oscillations, breakup and protection of strongly interacting fermion pairs. We show that measurement backaction can be exploited for realizing quantum states with spatial modulations of the density and magnetization, thus overcoming usual requirement for a strong interatomic interactions. We propose detection schemes for implementing antiferromagnetic states and density waves and we demonstrate that such long-range correlations cannot be realized with local addressing. Finally, we describe how to stabilize these emerging phases with the aid of quantum feedback. Such a quantum optical approach introduces into many-body physics novel processes, objects, and methods of quantum engineering, including the design of many-body entangled environments for open systems and it is easily extendable to other systems promising for quantum technologies.
28
Mathieu, Nathalie. „A study of atmospheric properties and their impact on the use of the nocturnal boundary layer budget technique for trace gas measurement /“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82291.
Annotation:
While most micrometeorological measurement techniques are only suitable for windy conditions, the Nocturnal Boundary Layer Technique can be used to measure trace gas flux during calm, clear nights as the nighttime stability enables gas emitted at the ground to accumulate. The difference between two measurements over the whole depth of this layer is believed to integrate emissions from a large area representative of, in this study, an agricultural farm. A tethersonde and infrared gas analyzer attached to a blimp carrying a bag sampling system monitored atmospheric variables for each ascent during two summer field campaigns. A mini-SODAR was installed in the field to obtain the wind flowfield. Strong accumulation was observed under low level jets suggesting that this feature acts as a good lid for trace gases. An average background vertical motion different from zero seemed to have more influence on gas propagation than did intermittent turbulence. On at least one night, a density current created by the nearby St-Lawrence River was observed to influence measurements.
29
Hartmann, Gregor [Verfasser], Uwe [Akademischer Betreuer] Becker, Thomas [Akademischer Betreuer] Möller und Jens [Akademischer Betreuer] Viefhaus. „Coherence effects of diatomic homonuclear molecules and sequential two-photon processes of noble gases in the photoionization / Gregor Hartmann. Gutachter: Thomas Möller ; Jens Viefhaus. Betreuer: Uwe Becker“. Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1065669879/34.
30
Galambos, James Paul. „Measurement of the internal toroidal magnetic field on the helicity injected tokamak using the transient internal probe /“. Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10674.
31
Roos, Andreas. „Single photon double valence ionization of methyl monohalides“. Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-239195.
Annotation:
This thesis is based on experimental results from measurements on methyl halides at a photon energy corresponding to the He IIβ emission line. Double ionization processes involving the valence electrons of the molecules CH3F, CH3Cl and CH3I are studied by means of a magnetic bottle TOF-PEPECO spectrometer. Resulting double ionization data of these molecules suggest that mainly direct double photoionization is observed as a continuous energy sharing between the ejected electron pairs. As a mean to further understand the double ionization processes, a "rule of thumb", for double ionization in molecules, is applied to the data presented in the double ionization spectra. This is done in order to quantify the effective distance between the two vacancies created in the dications. It is found that the distance between the vacancies may be related to the bond distance between the carbon and halogen atoms. Further investigations call for quantum chemical calculations to scrutinize this hypothesis.Det här examensarbetet är baserat på experimentella fotojonisations studier av metyl halider vid en fotonenergi motsvarande He IIβ emissionslinjen. Valenselektronerna i dubbeljonisations processerna för CH3F, CH3Cl och CH3I har studerats under användning av en så-kallad magnetisk flask TOF-PEPECO spektrometer. Resultaten av dessa mätningar visar att mestadels direkt dubbeljonisation processer före- kommer, där elektronerna delar kontinuerligt på energin som friges vid jonisationen. Den dubbla jonisa- tions processen är ytterligare studerad genom att tillämpa en tumregel för dubbeljonisation i molekyler, vilket ger en indikation av hur stort avståndet är mellan de två vakanserna som skapades när molekylerna joniserade. Resultaten från tumregeln visar att avståndet mellan vakanserna kan vara relaterade till bind- ningsavståndet mellan kol-atomen och halogen-atomen, i respektive metyl halogen. För att ytterligare bekräfta dubbeljonisations processerna i dessa molekyler, krävs kvantmekaniska beräkningar.
32
Lindsay, Clifford Fry. „The Measurement of Decomposition Products of Select Gases as an Indicator of a Concealed Mine Fire“. Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51091.
Annotation:
Currently, techniques used to determine whether or not there is a concealed fire in an inaccessible area of a coal mine are not definitive. Inaccessible areas of coal mines include:
1. A mined-out area, such as a long-wall gob.
2. A mine area, or entire mine, that has been sealed to extinguish a fire.
3. The interior of pillars in a mine.
4. Abandoned mines.
Mined-out areas — gobs — are particularly problematic. The standard practice is to obtain measurements for certain gas concentrations from an inaccessible area, and to apply certain rules to the obtained concentrations in order to try to decipher whether or not there is a fire in the area. Unfortunately, none of the gas measurements, and the associated rules that are applied, are free of potential problems. Therefore, there is always some degree of uncertainty in any decision that is based on the current methods.
A more definitive method of determining whether or not a concealed fire exists would be valuable; perhaps avoiding unnecessary exposure of miners to risks, and unnecessary exposure of mining companies to economic loss. This study details the inadequacies of the current methods for determining the presence of a fire in an inaccessible area of a coal mine, and proposes two novel methods for overcoming the current inadequacies.
The first method that was studied involves looking for the presence of the radioisotope carbon-fourteen in the carbon monoxide in the return airways of coal mines. For the vast majority of coal mines, if there is no fire anywhere in the coal mine, carbon monoxide should not have any carbon-fourteen in it. If there is a fire, the carbon monoxide should have carbon-fourteen in it. This method is based on the Boudouard Reaction, which documents a reaction between carbon, carbon monoxide, and carbon dioxide that only occurs at temperatures that only occur with a fire. Because of the very small amounts of carbon-fourteen in carbon dioxide in the atmosphere, and the small amount of carbon monoxide usually present in a coal mine atmosphere, there does not appear to be any way, currently, to implement this method. Instrumentation that may allow implementation of this method, in the future, is discussed.
The second method, that was studied, involves introducing a select, gaseous, organic compound into an inaccessible area; and then using a gas chromatograph to test for the presence of definitive fire decomposition products of the initial organic compound in the atmosphere that is exiting the inaccessible area.
Laboratory tests, conducted as part of this study, established the concept of this novel method of using select, organic compounds for definitively determining whether or not a concealed fire exists in an inaccessible part of a coal mine. Based on an initial screening of 5 different compounds, two compounds have been selected for use as 'fire indicator gases' with the acronym of 'FIGs.' These two compounds are:
1. C6-Perfluoroketone (CF3CF2C(=O)CF(CF3)2 )
2. 1,1 Difluoroethane (CH3CHF2)
This study provides suggestions as to how to look for other potential FIGs, and how to improve the testing of potential FIGs.
Examples of all four of the types of inaccessible areas listed above are discussed, particularly from the viewpoint of how FIGs could be utilized in each case, and how FIGs could provide better information in each case.
In addition, as a by-product of the experiments conducted for this work, this study identifies at least six gases that might be used simultaneously as tracer gases for complex ventilation studies in a mine, or elsewhere.Ph. D.
33
Chapanian, Rafi. „Study of accumulation of gases in vacuum systems: Measurement of gas transport properties of polymeric films“. Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26598.
Annotation:
In this thesis we have proven that the resistance to accumulation of gases in vacuum tubes is not always negligible. The process of accumulation was described using the Fick's second law of diffusion. The diffusion coefficient was assumed constant and evaluated, depending on pressure, considering Knudsen diffusion, molecular diffusion, or a combination of them. Experimental system with tubes of different lengths and diameters was built and equipped with two high sensitivity pressure transducers to measure the dynamic pressure difference along the system during gas flow experiments. Two cases were considered. First, the governing partial differential equation was solved analytically assuming a constant flow of gas into the system. Experimentally, a low-flow mass flow controller provided the constant flow of gas into the system. In the second case, the governing partial differential equation was solved numerically assuming a time-dependent flow of gas given by the Barrer equation. (Abstract shortened by UMI.)
34
Gordon, Robert J. (Robert James) 1940. „Field estimates of ammonia volatilization from swine manure by a simple micrometeorological technique“. Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63905.
35
Bates, Ian. „Identification of nonlinear processes in space plasma turbulence“. Thesis, University of Sheffield, 2003. http://etheses.whiterose.ac.uk/15136/.
Annotation:
Frequency domain analysis tools have been developed to analyse simultaneous multi-point measurements of developed space plasma turbulence. The Coherence Length technique enables the scale length for plasma wave structures to be measured from magnetic field measurements. The coherence length defines a length scale for the measurement of wave phenomena. Single satellite measurements can be used, the technique becoming more reliable with higher numbers of satellites. The technique is used to identify coherence lengths for waves observed in the magnetic field near the bow shock by the dual AMPTE-UKSIAMPTE-IRM satellites, and for mirror wave structures observed in the magnetic field in the magnetosheath by the dual ISEE-lIISEE-2 satellites. The Transfer Function Estimation technique enables the transfer of energy between plasma waves to be measured, from simultaneous dual-point measurements, resulting in linear growth / damping rates and second-order wave coupling. The technique is improved by replacing the Least Squares method for inversion with Regularisation. The technique is applied to simultaneous magnetic field measurements near the bow shock by the AMPTE-UKSIAMPTE-IRM satellites, where a linear instability in the wave field is identified, which is attributed to an ion anisotropy instability, and accompanying sequence of second-order three-wave coupling processes is also identified, which dissipates the energy from the linear instability. The Wave vector Determination technique enables the identification of wave vectors from simultaneous four-point measurements. The availability of four-point measurements means that the reliance on Minimum Variance Analysis, and that of only being able to use magnetic field measurements, is removed, the wave vector can be determined unambiguously directly from the magnetic field measurements. The technique can identify between waves of different frequency, and waves at the same frequency but propagating in different directions. The technique is applied to simultaneous observations of the electric field by the four-point ii Cluster II satellites, enabling the determination of the wave vector and the identification of a mirror mode structure, solely from the electric field measurements. Chapter 1 introduces the solar-terrestrial environment, briefly describing exploration of this environment by man-made satellites and listing some aims of the analysis of data collected by the satellites. Chapter 2 elaborates on what is meant by data analysis; Spectral Transforms are introduced and described, with a comparison made between Fourier Transforms and Wavelet Transforms, before a review is made of current data analysis techniques for satellite data. Chapter 3 defines and focuses attention on the objectives of this thesis, which are addressed in the following three chapters. Chapter 4 investigates the coherence length of plasma waves through use of the Wavelet Transform and the Fourier Shift Theorem. Chapter 5 makes estimates of wave Transfer Functions, replacing an established Least Squares inversion technique with a Regularisation inversion. Chapter 6 uses a method to determine wave propagation directions, from multi-satellite data, that has not been applied before due to the lack of availability of suitable data sets. Chapter 7 summarises the preceding chapters. The Appendices contain reprints of papers resulting from, and relating to, this research.
36
Geibel, Marc Christoph [Verfasser], Wolfgang [Akademischer Betreuer] Weigand und Christoph [Akademischer Betreuer] Gerbig. „Measurement of climate-relevant trace gases via infrared spectroscopy / Marc Christoph Geibel. Gutachter: Wolfgang Weigand ; Christoph Gerbig“. Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2011. http://d-nb.info/1016620160/34.
37
Kim, Ki-Yong. „Measurement of ultrafast dynamics in the interaction of intense laser pulses with gases, atomic clusters, and plasmas“. College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/93.
Annotation:
Thesis (Ph. D.) -- University of Maryland, College Park, 2003.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
38
Wolff, Mareile A. „Development of a novel balloon-borne optical sonde for the measurement of ozone and other stratospheric trace gases“. [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979701732.
39
Lewis, Kristin A. „Development of a dual-wavelength photoacoustic instrument for measurement of light absorption and scattering by aerosol and gases“. abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3258842.
40
Sampaio, Carlos Augusto de Paiva. „Caracterização dos ambientes termico, aereo e acustico em sistemas de produção de suinos, nas fases de creche e terminação“. [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257238.
Annotation:
Orientador: Irenilza de Alencar NaasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
Made available in DSpace on 2018-08-04T02:45:00Z (GMT). No. of bitstreams: 1 Sampaio_CarlosAugustodePaiva_D.pdf: 1948134 bytes, checksum: b2e69a6cda73b5e8d5079c6d3b0df732 (MD5) Previous issue date: 2004
Resumo: Emissão e concentração de aerossóis, gases e vapores provenientes do confinamento de animais causam danos à atmosfera, ao ambiente, ao homem e aos animais e às estruturas das instalações. Os contaminantes aéreos possuem efeito negativo sobre a saúde e produtividade dos animais e dos trabalhadores, que expostos a tais substâncias podem desenvolver problemas como irritação do sistema respiratório, pneumonite de hipersensibilidade, bronquite crônica, inflamações das vias aéreas, infecções respiratórias, asma ocupacional, febre e irritação nos olhos, dentre outros. Informações sobre ruídos, gases e poeira e seus efeitos no bem-estar do animal e do trabalhador em sistemas de produção de suínos para as condições brasileiras são escassas, pois estes estudos em sua grande maioria, são relacionados a países de clima temperado, onde as construções são completamente fechadas e o resultado final do ambiente difere das condições brasileiras, além do fator clima e manejo a ser considerado. Este trabalho possui os seguintes objetivos: avaliar o conforto térmico; a concentração de amônia (NH3), sulfeto de hidrogênio (H2S), metano (CH4), monóxido de carbono (CO), oxigênio (O2) e poeira; o ruído e estimar os riscos de exposição ocupacional a estes agentes ambientais. O estudo foi realizado em três granjas de ciclo completo de produção: Granja 1 (creche e terminação, ambos de piso compacto) e Granja 2 (creche de piso semi-ripado e terminação de piso compacto com lâmina d'água), durante o verão e inverno de 2003; Granja 3 (creche de salas com piso semi-ripado e gaiolas), durante o verão de 2002. Nestas instalações, era usada somente a ventilação natural para fins térmicos e higiênicos. Verificou-se que as concentrações médias de H2S e CO ficaram abaixo de 1 ppm e inferiores a 0,1% de CH4 em volume no ar, não ultrapassando os limites recomendados pela CIGR (1994) aos animais e aos limites recomendados pelas NR-15 (1978) e ACGIH (2001) para o trabalhador. A concentração de O2 ficou em média 21%. Com relação ao NH3, foram observadas diferenças (P < 0,05) nas concentrações médias em relação aos horários de alimentação dos animais, às tipologias das instalações e aos períodos avaliados. As análises dos dados revelam a necessidade de se melhorar a qualidade do ar, dando ênfase principalmente aos horários mais quentes e às condições de inverno, já que basicamente o NH3 encontra-se em concentração mais alta em relação à recomendada em diversos estudos. A concentração de poeira foi muito variável, sendo que a concentração de poeira total foi mais alta na creche (0,84 - 9,16 mg.m-3) do que na terminação (0,84 - 3,34 mg.m-3) e a concentração de poeira respirável foi mais alta nas unidades de creche, porém inferior a 3,67 mg.m-3, não apresentando riscos à saúde. As concentrações dessas substâncias (gases e poeira) foram inferiores àquelas verificadas em instalações fechadas. O ruído contínuo e de impacto se manteve nos limites recomendados pelas NR-15 (1978) e ACGIH (2001), podendo-se considerar o ambiente salubre. Entretanto, considerando o ruído de pico observado nos horários de alimentação e vacinação principalmente nas instalações para terminação, recomenda-se o uso de equipamento de proteção auricular. Na Granja 3, notou-se que o ruído contínuo e de pico na sala de creche com gaiolas foi superior ao ruído na sala de piso semi-ripado, o que pode estar relacionado a um maior bem-estar dos animais criados no piso semi-ripado. Verificou-se também a tendência do ruído de se acompanhar as condições de conforto térmico das instalações
Abstract: Emissions and concentrations from livestock buildings must be identified and analyzed with regard potential detrimental or hazardous effects on the atmosphere, man, animals, buildings and environment. Substantial evidence shows that some gases and particulates have a negative effect on health and productivity of animals. Labor in livestock buildings are exposed to a complex mixture of aerial contaminants and some can develop respiratory problems including irritation and inflammation of the respiratory tract, hypersensibility pneumonitits, chronic bronchitis, respiratory infections, occupational asthma and toxin fever and irritation of the eyes. Information about noise, dust and gases concentrations and the effects on animal¿s welfare and the workers in swine systems confinements production are rare in tropical regions. The majorities of the information addresses regions where the livestock buildings are total enclosed and the conditions of climate and manage are different too. This study was carried out during summer and winter of 2002/2003 and the objectives were: to evaluate the noise environment, air quality (NH3, H2S, CH4, CO, O2 and dust concentrations), the environment thermic, and estimate the occupational risk exposition the workers at three commercial swine production facilities: Housing 1 - growing and finishing with full slatted floors, Housing 2 - growing with partially slotted floor (40% of the pen area) and finishing of full slatted floors with thing layer of water in behind to the stalls and Housing 3 - growing with suspend cages and semi-slotted floor rooms of breeding. In the housings was used natural ventilation for thermal and hygiene environment control. The respective concentrations of H2S, CO, O2 and CH4 were less than 1 ppm, less than 1 ppm, 21.0% and less than 0.1% by volume. The concentrations of substances during these measurements are not dangerous of the animals and the workers as according to CIGR (1994), NR-15 (1978) and ACGIH (2001). The average concentration of NH3 presented significant difference (P < 0.05) with regard to feeding schedule, typology and periods available. The analyses of ammonia showed that some schedule mainly during winter are necessary attention especial because these concentrations were higher than most recommended by several studies. Total dust concentrations were the lowest for finishing units (0.84 - 3.34 mg.m-3) and the highest for growing units (0.84 - 9.16 mg.m-3). The respirable dust concentrations were highest than for growing units, and less than 3.67 mg.m-3. These concentrations were less than the limits recommended of the workers. The airborne concentrations of substances measured in the present study were all lower than most of published studies conducted in mainly enclosed swine buildings. The noise level (continuous and impact) were less than recommended by norms (NR-15 and ACGIH), however the peak noise level observed during feed alimentation and other task schedule mainly finishing swine housing recommended ear protection. In Housing 3 observed that noise continuous and peak in the room with suspend cages were highest than semi-slotted floor. These measurements indicated higher welfare the animals in the semi-slotted floor breeding. There was also tendency to increase the noise as thermal comfort environment conditions decreases
Doutorado
Construções Rurais e Ambiencia
Doutor em Engenharia Agrícola
41
Doshi, Viral V. „MEASUREMENT OF ALGAL GROWTH RATE BETWEEN HARVESTS IN AN ARTIFICIALLY LIT PHOTOBIOREACTOR UNDER FLUE GAS CONDITIONS“. Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1164057276.
42
Suleiman, David. „Measurement and prediction of phase equilibrium properties at infinite dilution : alkanes in natural gases and organic solvents in aqueous solutions“. Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/10270.
43
Combs, Roger J. „Gaseous diffusion in liquids“. Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/76484.
Annotation:
Diffusivity of nonreactive gases in liquids provides a means of interpreting structure in the liquid state. Structural models of the liquid state include Hildebrand's condensed gas model and Eyring's pseudo-lattice model. The former model predicts a linear dependence of diffusivity with temperature while the latter model predicts linear dependence of log(D) versus 1/T. The limited temperature dependent diffusivity data to date with a typical precision of ± 5% do not permit distinguishing which temperature dependence is more linear. However, the present investigation shows that diffusivities of one gas solute in two nonpolar liquids indirectly supports a linear diffusivity temperature dependence by a Graham's law like relation. At a fixed temperature this relation equates relative diffusivities to the square root of the inverse molecular weights of the respective liquids.
Diffusion of gases into nonpolar liquids have previously been measured by two techniques: (1) a pseudo-steady state technique developed by Hildebrand with diffusion through multiple capillaries and (2) a method by Walkley with diffusion through an open tube. Each of these methods requires prior knowledge of solubility of the gas in the liquid. An apparatus is constructed which combines these methods into a single experiment. Simultaneous solution of the two equations which describe the combined experiment yields both the solubility and diffusion coefficient. Diffusivities and solubilities of nitrogen, argon and oxygen into liquids of carbon tetrachloride and benzene as well as oxygen into water have been studied. The results compare favorably with the Literature.
The diffusion cell for this technique consists of a capillary disk, which is flooded with liquid. Gas is admitted into the space over the open solvent. With temperature and pressure constant, volume uptake of the gas in the solvent is monitored. Time-volume uptake data is evaluated by the two diffusion equations. Although the experiment is conceptually easy, a small gas volume change over a prolonged period of time poses problems in data collection and experiment control. The data collection and control is simplified by dedicating a Microcomputer Interfaced Data Acquisition System (MIDAS) to the experiment.Ph. D.
44
Sanches, Vivian Leme. „Remediação de solos da formação São Paulo contaminados por vapores de gasolina“. Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-15092009-161203/.
Annotation:
O presente trabalho teve por objetivo apresentar e discutir um caso de identificação e remediação emergencial de compostos orgânicos voláteis, oclusos em camada arenosa do Terciário da Formação São Paulo, em decorrência do vazamento de tanques de combustíveis de um posto de serviços. A técnica de remediação adotada para o caso consistiu na extração in situ dos vapores do solo e no tratamento dos mesmos por adsorção em filtros de carvão ativado (SVE - soil vapor extraction). Os processos de seleção, projeto, implantação, operação e descomissionamento da tecnologia SVE seguiram as metodologias indicadas pela literatura, adaptadas às condições locais. O acompanhamento da eficiência da remediação foi baseado na quantificação inicial dos hidrocarbonetos totais de petróleo leves presentes no subsolo, através das técnicas de cromatografia gasosa e espectrometria de massa, e na medição em campo das concentrações de voláteis e dos respectivos teores de explosividade. O resultado da campanha laboratorial apresentou fortes indícios de que a contaminação local fosse proveniente do combustível gasolina e indicou a ocorrência do composto benzeno em concentrações superiores aos limites adotados como referência. As leituras realizadas em campo mostraram rápido declínio das concentrações de voláteis e dos teores de explosividade com a operação da tecnologia SVE, indicando baixa ocorrência de fatores limitantes do transporte de massa no local. Corroborou com tal hipótese, o fato das metas de remediação terem sido atingidas com poucas trocas de ar, parâmetro retro-analisado a partir de dados de ensaios geológico-geotécnicos. Assim, concluiu-se que, para áreas com características semelhantes à estudada, a tecnologia SVE pode ser eficiente como medida de remediação de voláteis e redução dos riscos de explosividade.This work aims to present and to discuss a case study of identification and emergency remediation of volatile organic compounds, occluded in a sand layer of the São Paulo Tertiary Formation, as a result of the leakage of fuel tanks of a service station. The adopted remediation technique was in situ soil vapor extraction (SVE) and offgas treatment for adsorption in activated carbon filters. Selection, design, commissioning, operation and shutdown processes of SVE technology followed literature methodologies, which were adapted to local conditions. Remediation efficiency monitoring was based on the initial quantification of light total petroleum hydrocarbons in the subsoil, through gas chromatography and mass spectrometry techniques, and on measurement of the volatile concentrations and respective explosive contents in the field. The result of the laboratorial campaign presented strong indications that the local contamination proceeded from combustible gasoline and it indicated the occurrence of benzene in concentrations higher than the adopted reference. Field measurements showed fast decline of the volatile concentrations and explosive contents with the SVE technology operation, fact that indicated low occurrence of mass transfer limitations in the place. The fact that remediation goals were achieved with few air exchanges, parameter back-analyzed from geologicgeotechnical tests, contributed to reinforce such hypothesis. Thus, SVE technique can be considered efficient for volatile remediation and explosive risks reduction, for areas with characteristics similar to the studied one.
45
Estellés, Barber Fernando. „Development and evaluation of methods for the measurement of airborne emissions form animal houses“. Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/9036.
Annotation:
Airborne emissions from livestock production are nowadays one of the major concerns of this activity. For this reason, the reduction of these emissions is a requirement in many countries. The development of abatement techniques for the reduction of emissions needs for accurate knowledge about their magnitude. Emission measurement techniques arise then as a key issue. The development of measurement techniques considering not only the accuracy of the results but also the optimization of resources is needed. In this sense, in this thesis a tool and three options for the rationalization on the use of resources when measuring airborne emissions are investigated. The tool is the uncertainty analysis and the three options are: downscaling measurements, indirect measurement of airflow rates and reduction of sampling rates. In this thesis, theoretical and practical studies were conducted to determine the suitability of these techniques to obtain reliable data from more rational measurements on airborne emissions. Firstly, an uncertainty model was developed in order to assess the trustworthiness of the results when determining N2 and N2O emissions from a biological scrubber using a combined N-balance in air and water. This model was later partially validated throughout an experimental work in a chemical scrubber. The uncertainty model and the experimental work agreed in the key results of both studies, finding that N-balances were not successful for the proposed aims. Secondly, a flux chamber for the measurement of gas emissions from rabbits was designed and built. A measuring protocol for gas emissions from both animals and their manure was also developed. This chamber was later used to determine the CO2 emission rate from fattening rabbits during the whole fattening cycle. Using this CO2 emission rate from fattening rabbits, the carbon dioxide balance was tested as an option to determine the ventilation rate from fattening rabbit houses. The results of these balances were
compared with direct measurements of ventilation rates finding no statistical differences.
Finally, the effect of reducing sampling when measuring ammonia emissions from
livestock facilities was evaluated. Emissions calculated using semi-continuous
measurements of NH3 concentrations and airflow rates were compared with emissions
calculated on 24-hour average values for these parameters. The error committed with
these low time-resolution measurements resulted to be low in comparison with other
error sources committed when measuring emissions from livestock facilities. The main
conclusion of this work is that there are available techniques that allow optimizing the use
of resources of measurement processes, by keeping the accuracy of the results.Estellés Barber, F. (2010). Development and evaluation of methods for the measurement of airborne emissions form animal houses [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/9036
Palancia
46
Radney, James Gregory. „Development of a Nephelometry Camera and Humidity Controlled Cavity Ring-Down Transmissometer for the Measurement of Aerosol Optical Properties“. PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/907.
Annotation:
A Nephelometry camera (NephCam) and Humidity Controlled Cavity Ring-Down Transmissometer (HC-CRDT) were developed for the determination of aerosol optical properties. The NephCams use a reciprocal geometry relative to an integrating nephelometer; a diode laser illuminates a scattering volume orthogonal to a charge coupled device (CCD). The use of a CCD allows for measurement of aerosol scattering in 2 dimensions; scattering coefficients and size information can be extracted. The NephCam's optics were characterized during a set of imaging experiments to optimize the images collected by the camera. An aperture setting of 1.6 was chosen because it allowed for the most light intensity to reach the CCD - albeit with significant vignetting - and also had a constant modular transfer function (MTF) across the image; approximately 0.3. While this MTF value is approaching the minimum usable MTF of 0.2, other aperture settings did not exhibit constant MTF. While the effects of vignetting can be corrected in image post processing, the effects of non-constant MTF cannot. An optical response model was constructed to simulate images collected by the NephCams as a function of particle type and size. Good agreement between modeled and measured images was observed after the effects of contrast on image shape were considered. The image shapes generated by the model also pointed towards the use of polynomial calibration for particle sizes less than 400 nm as a result of multiple charge-to-size effects present from the sizing mechanism of the differential mobility analyzer. Initial calibration of the NephCams using size-selected dry Ammonium sulfate (AS) showed that calibration slopes are a function of particle size which is also in agreement with the model. Calibration slopes decreased as particle size increased to 400 nm; after 400 nm calibration slope oscillated around a common value. This effect is directly related to the forward shift of scattered intensity as particles grow in size and the collection efficiency of the NephCam as particle size increases. The single scattering albedo (SSA) of Nigrosin was calculated using the NephCam; extinction was measured by the HC-CRDT. Good agreement between the SSA and size was noticed for larger particle sizes; particles smaller than 200 nm in diameter over-measured the SSA of Nigrosin because of the multiple charge-to-size effect. In this size regime, light scattering by particles increases much more quickly than absorption; the presence of larger particles causes scattering to be artificially high. The HC-CRDT is a 4 channel, 3 wavelength instrument capable of measuring the extinction coefficients of aerosols at high (> 80%), low (< 10%) and ambient relative humidity. Extinction coefficients as a function of RH were determined for AS, NaNO3, NaCl, and Nigrosin; these particles represent surrogates of the strongly scattering ionic salts and black carbon, respectively. A model was developed to calculate the changes in refractive index and extinction coefficients of these water soluble particles as a function of RH; these particle types were chosen because core-shell morphologies could be avoided. Volume mixing, Maxwell-Garnett and partial molar refraction mixing rules were used to calculate effective refractive indices as a function of water uptake. Particle growth was calculated based upon the Kelvin equation. Measured and modeled results of f(RH) - relative change in extinction between high or ambient RH and dry RH - agree well for all particle types except Nigrosin. This disagreement is thought to stem directly from an incomplete parameter set for Nigrosin; growth parameters were assumed to be identical to NaNO3, density assumed to be 1 g/mL and molecular weight 202 g/mole, which may not be true in reality (different suppliers of Nigrosin quote different molecular weights). The NephCam was not used during these experiments, so the addition of a scattering measurement to better characterize the growth by Nigrosin is necessary. The f(RH) data for NaNO3 showed excellent agreement between measured and modeled data; however particle size information collected by an SMPS does not agree with the theory. This stems from the fact that NaNO3 does not show prompt deliquescence upon drying; instead an amorphous solid forms which exhibits a kinetically limited loss of water.
47
Aguilar, Gallardo Orlando Alexis. „Measurement and control of greenhouse gas emissions from beef cattle feedlots“. Diss., Kansas State University, 2012. http://hdl.handle.net/2097/15167.
Annotation:
Doctor of PhilosophyDepartment of Biological and Agricultural Engineering
Ronaldo Maghirang
Emission of greenhouse gases (GHGs), including nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from open beef cattle feedlots is becoming an environmental concern; however, scientific information on emissions and abatement measures for feedlots is limited. This research was conducted to quantify GHG emissions from feedlots and evaluate abatement measures for mitigating emissions. Specific objectives were to: (1) measure N2O emissions from the pens in a commercial cattle feedlot; (2) evaluate the effectiveness of surface amendments in mitigating GHG emissions from feedlot manure; (3) evaluate the effects of water application on GHG emissions from feedlot manure; and (4) compare the photo-acoustic infrared multi-gas analyzer (PIMA) and gas chromatograph (GC) in measuring concentrations of N2O and CO2 emitted from feedlot manure. Field measurements on a commercial beef cattle feedlot using static flux chambers combined with GC indicated that N2O emission fluxes varied significantly with pen surface condition. The moist/muddy surface had the largest median emission flux; the dry and compacted, dry and loose, and flooded surfaces had significantly lower median emission fluxes. Pen surface amendments (i.e., organic residues, biochar, and activated carbon) were applied on feedlot manure samples in glass containers and evaluated for their effectiveness in mitigating GHG emissions. Emission fluxes were measured with the PIMA. For dry manure, all amendments showed significant reduction in N2O and CO2 emission fluxes compared with the control (i.e., no amendment). For moist manure, biochar significantly reduced GHG emissions at days 10 and 15 after application; the other amendments had limited effects on GHG emissions. The effect of water application on GHG emissions from feedlot manure was evaluated. Manure samples (with and without water application) were placed in glass containers and analyzed for GHG emission using a PIMA. For the dry manure, GHG emissions were negligible. Application of water on the manure samples resulted in short-term peaks of GHG emissions a few minutes after water application. Comparison of the GC and PIMA showed that they were significantly correlated but differed in measured concentrations of N2O and CO2. The PIMA showed generally lower N2O concentrations and higher CO2 concentrations than the GC.
48
Teama, Doaa Galal Mohammed. „A 30-Year Record of the Isotopic Composition of Atmospheric Methane“. PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/642.
Annotation:
Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH4 (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH4 sources. Measuring stable isotopes of atmospheric CH4 can constrain changes of CH4 sources. The main goal of this work is to interpret the CH4 trend from 1978-2010 in terms of its sources using measurements of CH4 mixing ratio and its isotopes. The current work presents the measurements and analysis of CH4 and its isotopes (δ13C and δD) of four air archive sample sets collected by the Oregon Graduate Institute (OGI). CH4 isotope ratios (δ13C and δD) were measured by a continuous flow isotope ratio mass spectrometer technique developed at PSU. The first set is for Cape Meares, Oregon which is the oldest and longest set and spans 1977-1999. The integrity of this sample set was evaluated by comparing between our measured CH4 mixing ratio values with those measured values by OGI and was found to be stable. Resulting CH4 seasonal cycle was evaluated from the Cape Meares data. The CH4 seasonal cycle shows a broad maximum during October-April and a minimum between July and August. The seasonal cycles of δ13C and δD have maximum values in May for δ13C and in July for δD and minimum values between September-October for δ13C and in October for δD. These results indicate a CH4 source that is more enriched January-May (e.g. biomass burning) and a source that is more depleted August-October (e.g. microbial). In addition to Cape Meares, air archive sets were analyzed from: South Pole (SPO), Samoa (SMO), Mauna Loa (MLO) 1992-1996. The presented δD measurements are unique measured values during these time periods at these stations. To obtain the long-term in isotopic CH4 from 1978-2010, other datasets of Northern Hemisphere mid-latitude sites are included with Cape Meares. These sites are Olympic Peninsula, Washington; Montaña de Oro, California; and Niwot Ridge, Colorado. The seasonal cycles of CH4 and its isotopes from the composite dataset have the same phase and amplitudes as the Cape Meares site. CH4 growth rate shows a decrease over time 1978-2010 with three main spikes in 1992, 1998, and 2003 consistent with the literature from the global trend. CH4 lifetime is estimated to 9.7 yrs. The δ13C trend in the composite data shows a slow increase from 1978-1987, a more rapid rate of change 1987-2005, and a gradual depletion during 2005-2010. The δD trend in the composite data shows a gradual increase during 1978-2001 and decrease from 2001-2005. From these results, the global CH4 emissions are estimated and show a leveling off sources 1982-2010 with two large peak anomalies in 1998 and 2003. The global average δ13C and δD of CH4 sources are estimated from measured values. The results of these calculations indicate that there is more than one source which controls the decrease in the global CH4 trend. From 1982-2001, δ13C and δD of CH4 sources becomes more depleted due to a decrease in fossil and/or biomass burning sources relative to microbial sources. From 2005-2010, δ13C of CH4 sources returns to its 1981 value. There are two significant peaks in δ13C and δD of CH4 sources in 1998 and 2003 due to the wildfire emissions in boreal areas and in Europe.
49
Wolff, Mareile. „Development of a novel balloon-borne optical sonde for the measurement of ozone and other stratopheric trace gases = Entwicklung einer ballongestützten optischen Sonde zur Messung von Ozon und anderen stratosphärischen Spurengasen /“. Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2007. http://www.loc.gov/catdir/toc/fy0711/2007425447.html.
50
Wolff, Mareile. „Development of a novel balloon-borne optical sonde for the measurement of ozone and other stratospheric trace gases = Entwicklung einer ballongestützten optischen Sonde zur Messung von Ozon und anderen stratosphärischen Spurengasen /“. Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2007. http://www.loc.gov/catdir/toc/fy0711/2007425447.html.