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1
McCarthy, Richard Ivor. "GUSTO : a differential UV absorption spectroscopy instrument." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430743.
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Collar, A. J. "Differential absorption lidar using an optical parametric oscillator source." Thesis, University of Southampton, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370334.
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Bobrowski, Nicole. "Volcanic gas studies by Multi Axis Differential Absorption Spectroscopy." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-60521.
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Sinreich, Roman. "Multi-Axis differential optical absorption spectroscopy measurements in polluted environments." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-80698.
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Kubera, Kimberly. "Evaluation of Upper Atmospheric Ozone Data provided by a Differential-Absorption Lidar." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6900.
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Ground-level ozone is an environmental and public health issue. Daily ozone forecasts are made to allow people to take precautions to protect their health. For this study, a prototype laser that measures ozone concentrations vertically throughout the atmospheric boundary layer was evaluated as tool for ozone forecasting.
To examine this data, three analyses were performed. First, it was determined if stratification, and thus residual layers, could be seen. This was conducted, in part, by examining hourly mixing heights overlaid onto color-coded NEXLASER charts. Each NEXLASER chart shows the horizontal and spatial distribution of the measured ozone concentrations during a twenty-four hour period. In the second analysis, the correlation value between the early morning upper-tropospheric ozone and the maximum 8-hour average surface ozone concentrations was determined. For the third analysis, a case study on two select groups of days was conducted.
This study suggested that NEXLASER can be used to detect the presence of residual layers and can be used as an aid in predicting peak daily 8-hour average ground-level ozone concentrations. Specifically, days on which a morning ozone reservoir layer is most prominent have the most potential to lead to high surface ozone concentrations later in the day. While more research should be conducted, this study shows how this data could be useful in explaining ozone events, and thus be an aid to ozone forecasters.
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Jerez, Carlos J. "Measuring Atmospheric Ozone and Nitrogen Dioxide Concentration by Differential Optical Absorption Spectroscopy." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103336/.
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The main objective was to develop a procedure based on differential optical absorption spectroscopy (DOAS) to measure atmospheric total column of ozone, using the automated instrument developed at the University of North Texas (UNT) by Nebgen in 2006. This project also explored the ability of this instrument to provide measurements of atmospheric total column nitrogen dioxide. The instrument is located on top of UNT’s Environmental Education, Science and Technology Building. It employs a low cost spectrometer coupled with fiber optics, which are aimed at the sun to collect solar radiation. Measurements taken throughout the day with this instrument exhibited a large variability. The DOAS procedure derives total column ozone from the analysis of daily DOAS Langley plots. This plot relates the measured differential column to the airmass factor. The use of such plots is conditioned by the time the concentration of ozone remains constant. Observations of ozone are typically conducted throughout the day. Observations of total column ozone were conducted for 5 months. Values were derived from both DOAS and Nebgen’s procedure and compared to satellite data. Although differences observed from both procedures to satellite data were similar, the variability found in measurements was reduced from 70 Dobson units, with Nebgen’s procedure, to 4 Dobson units, with the DOAS procedure.A methodology to measure atmospheric nitrogen dioxide using DOAS was also investigated. Although a similar approach to ozone measurements could be applied, it was found that such measurements were limited by the amount of solar radiation collected by the instrument. Observations of nitrogen dioxide are typically conducted near sunrise or sunset, when solar radiation experiences most of the atmospheric absorption.
7
Smith, Nicola. "A spectroscopic study of the role of the nitrate radical in the troposphere." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297008.
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Lawrence, James. "Differential absorption LiDAR for the total column measurement of atmospheric CO2 from space." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10379.
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Since the beginning of the industrial revolution (1750 to 1800) the Earth’s atmospheric composition has undergone significant change as a result of human activities, in particular the burning of fossil fuels. As a consequence the atmospheric concentrations of a number of gases known to be influential to the Earth’s climate have increased far beyond natural levels. Atmospheric gases such as carbon dioxide which naturally exist in the Earth system have increased in correlation with anthropogenic emissions. The effect of this perturbation on the Earth system has been predicted through computer simulations to have undesirable consequences on the Earth’s future climate. The present measurement systems for atmospheric carbon dioxide have limited spatial coverage and temporal resolution which restricts their ability to accurately attribute observations of atmospheric composition to particular terrestrial sources and sinks. This inability to accurately locate and quantify the key carbon dioxide sources and sinks in the terrestrial and marine biospheres is hindering the understanding of the processes that are driving the Earth’s natural uptake of approximately half of the anthropogenic carbon dioxide emissions. With such uncertainty it is currently unknown precisely how the Earth’s climate will respond to global warming in the future. Through computer simulation it has been demonstrated that improving the spatial distribution of global measurements of atmospheric carbon dioxide is likely to advance the present understanding of the Earth’s terrestrial sources and sinks. Regions that require particular improvement in measurement coverage are the southern oceans owing to a lack of landmass on which to site instruments, and much of the tropics because of difficulties in locating instruments in some of the worlds more politically unstable regions. Satellite remote sensing instruments which measure atmospheric carbon dioxide from low Earth orbit provide some coverage of these sparsely sampled locations, however cloud cover often prevents measurements being made (particularly in the tropics), and limited latitudinal coverage caused by current instruments using passive remote sensing techniques prevents measurements at very high and low latitudes (including much of the southern ocean during local winter). An alternative remote sensing technique has been proposed in the scientific literature for measuring atmospheric carbon dioxide concentrations using laser emissions from a satellite platform known as total column differential absorption LiDAR (TC-DIAL). The TC-DIAL technique has been identified as having the theoretical potential to meet the coverage and precision requirements to greatly aid in identifying and quantifying terrestrial carbon dioxide sources and sinks. The TC-DIAL technique has the potential to achieve these goals largely owing to its unique capabilities of being able to make measurements during both the day and night and at all latitudes with a footprint which may be small enough to see between patchy cloud cover in the tropics. This thesis builds on previous studies of the TC-DIAL measurement technique from a satellite platform to assess its current and future capabilities to meet the observation requirements defined by the atmospheric carbon and modeling scientific communities. Particular investigations are carried out to assess the optimum system configuration in the context of global carbon modeling using up-to-date spectroscopy and instrument parameters for the latest technology. Optimum systems for both direct and heterodyne detection TC-DIAL instruments are defined, and it is found that direct detection provides the lowest retrieval errors under clear sky conditions. For a system based on current technology TC-DIAL retrievals are expected to have errors of approximately 0.68 ppm for direct detection and 1.01 ppm for heterodyne detection over a 50 km surface track. Using global cloud statistics two suitable pulse repetition frequencies (PRF) for a heterodyne detection system have been identified as 5 and 15 kHz. These PRF’s provide the minimum probability of an effect known as cross signal contamination occurring when measurements are made in the presence of cloud. In this thesis it is shown that the retrieval error incurred by cross signal contamination is > 16 ppm for a heterodyne detection TC-DIAL system measuring through cloud with optical depth > 2. The most important retrieval error component in TC-DIAL retrievals has been found to be the uncertainties introduced by the use of numerical weather prediction data for the ancillary atmospheric profiles. The limited spatial resolution of current NWP models (> 20 km) implies the uncertainties associated with the ancillary data are required to be treated as systematic, and as a consequence their errors dominate over other TC-DIAL retrieval errors following multiple pulse integration.
9
Nehrir, Amin Reza. "Water vapor profiling using a compact widely tunable diode laser Differential Absorption Lidar (DIAL)." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/nehrir/NehrirA1208.pdf.
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Atmospheric water vapor is an important driver of cloud formation, precipitation, and cloud microphysical structure. Changes in the cloud microphysical structure due to the interaction of aerosols and water vapor can produce more reflective clouds, resulting in more incoming solar radiation being reflected back into space, leading to an overall negative radiative forcing. Water vapor also plays an important role in the atmospheric feedback process that acts to amplify the positive radiative forcing resulting from increasing levels of atmospheric CO2. In the troposphere, where the water vapor greenhouse effect is most important, the situation is harder to quantify. A need exists for tools that allow for high spatial resolution range resolved measurements of water vapor number density up to about 4 km. One approach to obtaining this data within the boundary layer is with the Differential Absorption Lidar (DIAL) that is being developed at Montana State University. A differential absorption lidar (DIAL) instrument for automated profiling of water vapor in the lower troposphere has been designed, tested, and is in routine operation. The laser transmitter for the DIAL instrument uses a widely tunable external cavity diode laser (ECDL) to injection seed two cascaded semiconductor optical amplifiers (SOA) to produce a laser transmitter that accesses the 824-841 nm spectral range. The DIAL receiver utilizes a 28-cm-diameter Schmidt-Cassegrain telescope, an avalanche photodiode (APD) detector, and a narrow band optical filter to collect, discriminate, and measure the scattered light. A technique of correcting for the wavelength-dependent incident angle upon the narrow band optical filter as a function of range has been developed to allow accurate water vapor profiles to be measured down to 225 m above the surface. Data comparisons using the DIAL instrument and co-located radiosonde measurements are presented demonstrating the capabilities of the DIAL instrument.
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Obland, Michael Drew. "Water vapor profiling using a widely tunable amplified diode laser Differential Absorption Lidar (DIAL)." Diss., Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/obland/OblandM0507.pdf.
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Water vapor is one of he most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. Water vapor profiles are currently obtained with several remote sensing techniques, such as microwave radiometers, passive instruments like the Atmospheric Emitted Radiance Interferometer (AERI), and Raman lidar. Each of these instruments has some disadvantage, such as only producing column integrated water vapor amounts or being large, overly customized, and costly, making them difficult to use for deployment in networks or onboard satellites to measure water vapor profiles. This thesis work involved the design, construction, and testing of a highly-tunable Differential Absorption Lidar (DIAL) instrument utilizing an all-semiconductor transmitter. It was an attempt to take advantage of semiconductor laser technology to obtain range-resolved water vapor profiles with an instrument that is cheaper, smaller, and more robust than existing field instruments. The eventual goal of this project was to demonstrate the feasibility of this DIAL instrument as a candidate for deployment in multi-point networks or satellite arrays to study water vapor flux profiles. This new DIAL instruments transmitter has, for the first time in any known DIAL instrument, a highly-tunable External Cavity Diode Laser (ECDL) as a seed laser source for two cascaded commercial tapered amplifiers. The transmitter has the capability of tuning over a range of ~17nm to selectively probe several available water vapor absorption lines, depending on current environmental conditions. This capability has been called for in other recent DIAL experiments, Tests of the DIAL instrument to prove the validity of its measurements are presented, Initial water vapor profiles, taken in the Bozeman, MT, area, were taken, analyzed, and compared with co-located radiosonde measurements, Future improvements and directions for the next generation of this DIAL instrument are discussed.
11
Layfield, Andrew. "An evaluation of selected estimation methods for the processing of differential absorption lidar data." Thesis, University of Hull, 1987. http://hydra.hull.ac.uk/resources/hull:16436.
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This work examines the application of selected estimation methods to path integrated direct detection CO2 lidar data, with the objective of improving the precision in the estimates of the log power, and log power ratios. Particular emphasis is given to the optimal estimation techniques of Kalman filtering theory, and to the consequent requirements for system and measurement model identification. A dual wavelength system was designed and constructed, employing two hybridised TEA lasers, a co-axial transceiver, and direct detection. Over a period of several months, a database of differential absorption measurements was accumulated, each consisting of 10,000 dual wavelength lidar returns. Various wavelength pairs were used, including those recommended for the monitoring of H2O, CO2, NH3 and C2H4. A subset of this database is used to evaluate the above mentioned estimation methods. The results are compared with simulated data files in which it was possible to control precisely process models which are believed to form an approximation to the real processes latent in the actual lidar data.
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McDonald, Michael K. "Differential absorption measurements of total column ozone during polar night using modified stellar Brewer spectrometer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21305.pdf.
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Martin, Philip Nathaniel. "Measurements of atmospheric trace gases using open path differential UV absorption spectroscopy for urban pollution monitoring." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/11299.
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Beekman, Christopher Paul. "Differential Optical Absorption Spectroscopy of Trace Gas Species and Aerosols in the Upper Ohio River Valley." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1268143515.
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Yereniuk, Michael A. "Global Approximations of Agent-Based Model State Changes." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-dissertations/614.
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How can we model global phenomenon based on local interactions? Agent-Based (AB) models are local rule-based discrete method that can be used to simulate complex interactions of many agents. Unfortunately, the relative ease of implementing the computational model is often counter-balanced by the difficulty of performing rigorous analysis to determine emergent behaviors. Calculating existence of fixed points and their stability is not tractable from an analytical perspective and can become computationally expensive, involving potentially millions of simulations. To construct meaningful analysis, we need to create a framework to approximate the emergent, global behavior. Our research has been devoted to developing a framework for approximating AB models that move via random walks and undergo state transitions. First, we developed a general method to estimate the density of agents in each state for AB models whose state transitions are caused by neighborhood interactions between agents. Second, we extended previous random walk models of instantaneous state changes by adding a cumulative memory effect. In this way, our research seeks to answer how memory properties can also be incorporated into continuum models, especially when the memory properties effect state changes on the agents. The state transitions in this type of AB model is primarily from the agents’ interaction with their environment. These modeling frameworks will be generally applicable to many areas and can be easily extended.
16
Palazzi, Elisa <1978>. "Retrieval of trace gases vertical profile in the lower atmosphere combining. Differential Optical Absorption Spectroscopy with radiative transfer models." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/983/.
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The motivation for the work presented in this thesis is to retrieve profile
information for the atmospheric trace constituents nitrogen dioxide (NO2)
and ozone (O3) in the lower troposphere from remote sensing measurements.
The remote sensing technique used, referred to as Multiple AXis Differential
Optical Absorption Spectroscopy (MAX-DOAS), is a recent technique that
represents a significant advance on the well-established DOAS, especially for
what it concerns the study of tropospheric trace consituents.
NO2 is an important trace gas in the lower troposphere due to the fact that
it is involved in the production of tropospheric ozone; ozone and nitrogen
dioxide are key factors in determining the quality of air with consequences,
for example, on human health and the growth of vegetation. To understand
the NO2 and ozone chemistry in more detail not only the concentrations at
ground but also the acquisition of the vertical distribution is necessary. In
fact, the budget of nitrogen oxides and ozone in the atmosphere is determined
both by local emissions and non-local chemical and dynamical processes (i.e.
diffusion and transport at various scales) that greatly impact on their vertical
and temporal distribution: thus a tool to resolve the vertical profile
information is really important.
Useful measurement techniques for atmospheric trace species should fulfill
at least two main requirements. First, they must be sufficiently sensitive to
detect the species under consideration at their ambient concentration levels.
Second, they must be specific, which means that the results of the measurement
of a particular species must be neither positively nor negatively
influenced by any other trace species simultaneously present in the probed
volume of air. Air monitoring by spectroscopic techniques has proven to be
a very useful tool to fulfill these desirable requirements as well as a number
of other important properties. During the last decades, many such instruments
have been developed which are based on the absorption properties of
the constituents in various regions of the electromagnetic spectrum, ranging
from the far infrared to the ultraviolet. Among them, Differential Optical
Absorption Spectroscopy (DOAS) has played an important role.
DOAS is an established remote sensing technique for atmospheric trace
gases probing, which identifies and quantifies the trace gases in the atmosphere
taking advantage of their molecular absorption structures in the near
UV and visible wavelengths of the electromagnetic spectrum (from 0.25 μm
to 0.75 μm). Passive DOAS, in particular, can detect the presence of a trace
gas in terms of its integrated concentration over the atmospheric path from
the sun to the receiver (the so called slant column density). The receiver
can be located at ground, as well as on board an aircraft or a satellite platform.
Passive DOAS has, therefore, a flexible measurement configuration
that allows multiple applications.
The ability to properly interpret passive DOAS measurements of atmospheric
constituents depends crucially on how well the optical path of light
collected by the system is understood. This is because the final product of
DOAS is the concentration of a particular species integrated along the path
that radiation covers in the atmosphere. This path is not known a priori and
can only be evaluated by Radiative Transfer Models (RTMs). These models
are used to calculate the so called vertical column density of a given trace
gas, which is obtained by dividing the measured slant column density to the
so called air mass factor, which is used to quantify the enhancement of the
light path length within the absorber layers.
In the case of the standard DOAS set-up, in which radiation is collected
along the vertical direction (zenith-sky DOAS), calculations of the air mass
factor have been made using “simple” single scattering radiative transfer
models. This configuration has its highest sensitivity in the stratosphere,
in particular during twilight. This is the result of the large enhancement in
stratospheric light path at dawn and dusk combined with a relatively short
tropospheric path.
In order to increase the sensitivity of the instrument towards tropospheric
signals, measurements with the telescope pointing the horizon (offaxis
DOAS) have to be performed. In this circumstances, the light path in the
lower layers can become very long and necessitate the use of radiative transfer
models including multiple scattering, the full treatment of atmospheric
sphericity and refraction.
In this thesis, a recent development in the well-established DOAS technique
is described, referred to as Multiple AXis Differential Optical Absorption
Spectroscopy (MAX-DOAS). The MAX-DOAS consists in the simultaneous
use of several off-axis directions near the horizon: using this configuration,
not only the sensitivity to tropospheric trace gases is greatly improved,
but vertical profile information can also be retrieved by combining the simultaneous
off-axis measurements with sophisticated RTM calculations and
inversion techniques.
In particular there is a need for a RTM which is capable of dealing with
all the processes intervening along the light path, supporting all DOAS geometries
used, and treating multiple scattering events with varying phase
functions involved. To achieve these multiple goals a statistical approach
based on the Monte Carlo technique should be used. A Monte Carlo RTM
generates an ensemble of random photon paths between the light source and
the detector, and uses these paths to reconstruct a remote sensing measurement.
Within the present study, the Monte Carlo radiative transfer
model PROMSAR (PROcessing of Multi-Scattered Atmospheric Radiation)
has been developed and used to correctly interpret the slant column densities
obtained from MAX-DOAS measurements.
In order to derive the vertical concentration profile of a trace gas from
its slant column measurement, the AMF is only one part in the quantitative
retrieval process. One indispensable requirement is a robust approach to
invert the measurements and obtain the unknown concentrations, the air
mass factors being known. For this purpose, in the present thesis, we have
used the Chahine relaxation method.
Ground-based Multiple AXis DOAS, combined with appropriate radiative
transfer models and inversion techniques, is a promising tool for atmospheric
studies in the lower troposphere and boundary layer, including the retrieval of
profile information with a good degree of vertical resolution. This thesis has
presented an application of this powerful comprehensive tool for the study of
a preserved natural Mediterranean area (the Castel Porziano Estate, located
20 km South-West of Rome) where pollution is transported from remote
sources.
Application of this tool in densely populated or industrial areas is beginning
to look particularly fruitful and represents an important subject for future
studies.
17
Leigh, Roland. "A concurrent multi-axis differential optical absorption spectroscopy system for the measurement of nitrogen dioxide and other trace species." Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/30583.
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Despite improvements in efficiency in many combustion processes including vehicular engines, the level of nitrogen dioxide in the typical urban environment continues to impact a human health and requires regular monitoring. This thesis describes the development of a novel remote-sensing instrument configured for the measurement of nitrogen dioxide and other trace species in an urban environment.;A novel concurrent multi-axis differential optical absorption spectroscopy(CMAX-DOAS) system has been developed in this work based on scattered light spectroscopy. Data from the measurements has a temporal resolution of a minute or less and therefore the capability to spatially resolve different air masses as they traverse the instrument input optics. Such sampling capabilities are unique to a ground-based scattered-light DOAS system and are well suited to analysis of rapidly moving and distinct plumes in an urban environment.;The CMAX-DOAS instrument was built in 2002, and tested and validated during an intercomparison campaign in Norway in 2003. During 2004 concurrent measurements from multiple viewing geometries were made in Leicester (52.6 oN, 1.12o W). Measured slant columns of nitrogen dioxide from the CMAX-DOAS instrument have errors calculated at less than 2% for a single axis, and 4 to 6% for analysis using a reference spectrum from another axis. These measurements agree well with in situ measurements and identify significant boundary layer concentrations (up to 80 microg m--3) of nitrogen dioxide which clearly correlate with anthropogenic activity over diurnal, weekly and annual timescales.;Through concurrent measurement of different air masses, considerable information on individual plumes has been obtained, including estimates of source location, plume size provide on nitrogen dioxide emissions on an urban scale and are necessary to determine the link between urban activity, nitrogen dioxide emissions, air quality and ultimately human health.
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Rumburg, Brian Paul. "Differential optical absorption spectroscopy (DOAS) measurements of atmospheric ammonia in the mid-ultraviolet from a dairy concentrations, emissions, and modeling /." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Spring2006/b%5Frumburg%5F031006.pdf.
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Yilmaz, Selami [Verfasser], and Ulrich [Akademischer Betreuer] Platt. "Retrieval of Atmospheric Aerosol and Trace Gas Vertical Profiles using Multi-Axis Differential Optical Absorption Spectroscopy / Selami Yilmaz ; Betreuer: Ulrich Platt." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1179783867/34.
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Nehrir, Amin Reza. "Development of an eye-safe diode-laser-based micro-pulse differential absorption lidar (mp-DIAL) for atmospheric water-vapor and aerosol studies." Diss., Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/nehrir/NehrirA0811.pdf.
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This dissertation describes the design, construction, and testing of an all diode-laser-based water-vapor differential absorption lidar (DIAL) instrument through two distinct stages of development. A second generation low pulse energy, high pulse repetition frequency DIAL instrument was developed to overcome the power limitations of the first generation instrument which required unrealistic integration times approaching 1 hour. The second generation DIAL transmitter used a custom built external cavity diode laser (ECDL) as the seed source for an actively current pulsed tapered semiconductor optical amplifier (TSOA), yielding a maximum output transmitter pulse energy of 2 microjoules over a 1 microsecond duration pulse width at a 20 kHz pulse repetition frequency, decreasing the required integration Period to approximately 20-30 minutes. Nighttime and daytime water-vapor profiles were collected with the second generation DIAL instrument which showed good agreement with collocated radiosonde measurements from near the surface up to the top of the planetary boundary layer. Aerosol optical properties were also measured using the calibrated offline channel returns using the iterative Fernald solution to the lidar equation. Most recently, a third generation DIAL transmitter has been developed to further increase the output pulse energy and to also decrease the DIAL atmospheric spectral sampling time. Two custom built high power ECDL's and an electro-mechanical based fiber optic switch are used to sequentially seed a single stage actively current pulsed TSOA in order to minimize the systematic errors introduced in the DIAL retrievals resulting from air-mass miss-sampling between the two DIAL wavelengths. Peak output pulse energies of 7 microjoules have been measured over 1 microsecond pulse durations at a 10 kHz pulse repetition frequency with a 1-6 second DIAL spectral switching time, further decreasing the total required integration period to 20 minutes for both nighttime and daytime operation. The increased performance of the third generation transmitter has allowed for nighttime and daytime water vapor profiling under varying atmospheric conditions that shows good agreement with collocated radiosonde measurements up to ~ 6 km and ~ 3 km, respectively. A detailed description of the second and third generation DIAL instrument performance as well as data retrievals are presented in this dissertation. Future work to improve the current third generation DIAL instrument for full-time autonomous measurements of atmospheric water-vapor and aerosols is also discussed.
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Pal, Avishekh. "Laser Remote Sensing of Trace Chemical Species Using 10.6 μm CO2 Laser Enhanced Breakdown Spectroscopy and Differential Absorption Lidar." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/441.
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Several different laser remote sensing techniques related to the detection of trace chemical species were studied. In particular, a Differential-Absorption lidar (DIAL), a Laser-Induced-Breakdown Spectroscopy (LIBS) lidar, and a Raman lidar were studied. Several of the laser spectroscopic techniques that were used were common throughout these different studies. More precisely, 10.6 μm CO2 laser related spectroscopy was common for the DIAL and LIBS studies, and 266 nm Nd:YAG laser related spectroscopy was used for the LIBS and Raman studies.
In the first system studied a tunable CO2 DIAL system was developed for the first time to our knowledge for the potential detection of the explosive Triacetone Triperoxide (TATP) gas clouds. The system has been used to measure gas samples of SF6, and has shown initial absorption measurements of samples of TATP contained within an enclosed optical absorption cell. DIAL/Lidar returns from a remote retroreflector target array were used for the DIAL measurements after passage through a laboratory cell containing the TATP gas. DIAL measured concentrations agreed well with those obtained using a calibrated Ion Mobility Spectrometer. DIAL detection sensitivity of the TATP gas concentration in the cell was about 0.5 ng/μl for a 0.3 m path-length. However, the concentration of TATP was found to be unstable over long periods of time possibly due to re-absorption and crystallization of the TATP vapors on the absorption cell windows. A heated cell partially mitigated these effects.
In the second set of studies, a Deep UV LIBS system was developed and studied for the remote detection of solid targets, and potentially chemical, biological, and explosive substances. A 4th harmonic Q-Switched Nd:YAG laser operating at 266 nm was used for excitation of the LIBS plasma at standoff ranges up to 50 m . The LIBS plasma emission covering the range of 240 – 800 nm was enhanced by use of a nearly simultaneous 10.6 μm CO2 laser that increased the LIBS plasma emission by several orders of magnitude. The emission spectrum was used to detect and identify the species of interest. Plasma temperatures on various solid substrates were measured. An increase in the plasma temperature of about 5000 K was measured and analyzed, for the first to our knowledge, due to the addition of the CO2 laser pulse to the LIBS plasma generated by the Nd:YAG laser. An optimum temporal overlap of the two laser pulses was found to be important for the enhancement.
Finally, in a third related lidar system, initial 266 nm Raman lidar studies were conducted at detection ranges of 15 m. However, significant spectroscopic background interferences were observed at these wavelengths and additional optical filtering is required.
22
Schmidt, Daniel. "Kinetic Monte Carlo Methods for Computing First Capture Time Distributions in Models of Diffusive Absorption." Scholarship @ Claremont, 2017. https://scholarship.claremont.edu/hmc_theses/97.
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In this paper, we consider the capture dynamics of a particle undergoing a random walk above a sheet of absorbing traps. In particular, we seek to characterize the distribution in time from when the particle is released to when it is absorbed. This problem is motivated by the study of lymphocytes in the human blood stream; for a particle near the surface of a lymphocyte, how long will it take for the particle to be captured? We model this problem as a diffusive process with a mixture of reflecting and absorbing boundary conditions. The model is analyzed from two approaches. The first is a numerical simulation using a Kinetic Monte Carlo (KMC) method that exploits exact solutions to accelerate a particle-based simulation of the capture time. A notable advantage of KMC is that run time is independent of how far from the traps one begins. We compare our results to the second approach, which is asymptotic approximations of the FPT distribution for particles that start far from the traps. Our goal is to validate the efficacy of homogenizing the surface boundary conditions, replacing the reflecting (Neumann) and absorbing (Dirichlet) boundary conditions with a mixed (Robin) boundary condition.
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Zielcke, Johannes [Verfasser], and Ulrich [Akademischer Betreuer] Platt. "Observations of reactive bromine, iodine and chlorine species in the Arctic and Antarctic with Differential Optical Absorption Spectroscopy / Johannes Zielcke ; Betreuer: Ulrich Platt." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180499611/34.
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Tsang, Chi-kin. "Analysis and control of organic vapours in air and determination of metals and toxic elements in fish samples by differential pulse voltammetry and atomic absorption spectrophotometry /." [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13408914.
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Tournier, Pierre-Henri. "Absorption de l'eau et des nutriments par les racines des plantes : modélisation, analyse et simulation." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066030/document.
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Dans le contexte du développement d'une agriculture durable visant à préserver les ressources naturelles et les écosystèmes, il s'avère nécessaire d'approfondir notre compréhension des processus souterrains et des interactions entre le sol et les racines des plantes.Dans cette thèse, on utilise des outils mathématiques et numériques pour développer des modèles mécanistiques explicites du mouvement de l'eau et des nutriments dans le sol et de l'absorption racinaire, gouvernés par des équations aux dérivées partielles non linéaires. Un accent est mis sur la prise en compte explicite de la géométrie du système racinaire et des processus à petite échelle survenant dans la rhizosphère, qui jouent un rôle majeur dans l'absorption racinaire.La première étude est dédiée à l'analyse mathématique d'un modèle d'absorption du phosphore (P) par les racines des plantes. L'évolution de la concentration de P dans la solution du sol est gouvernée par une équation de convection-diffusion avec une condition aux limites non linéaire à la surface de la racine, que l'on considère ici comme un bord du domaine du sol. On formule ensuite un problème d'optimisation de forme visant à trouver les formes racinaires qui maximisent l'absorption de P.La seconde partie de cette thèse montre comment on peut tirer avantage des récents progrès du calcul scientifique dans le domaine de l'adaptation de maillage non structuré et du calcul parallèle afin de développer des modèles numériques du mouvement de l'eau et des solutés et de l'absorption racinaire à l'échelle de la plante, tout en prenant en compte les phénomènes locaux survenant à l'échelle de la racine uniqueIn the context of the development of sustainable agriculture aiming at preserving natural resources and ecosystems, it is necessary to improve our understanding of underground processes and interactions between soil and plant roots.In this thesis, we use mathematical and numerical tools to develop explicit mechanistic models of soil water and solute movement accounting for root water and nutrient uptake and governed by nonlinear partial differential equations. An emphasis is put on resolving the geometry of the root system as well as small scale processes occurring in the rhizosphere, which play a major role in plant root uptake.The first study is dedicated to the mathematical analysis of a model of phosphorus (P) uptake by plant roots. The evolution of the concentration of P in the soil solution is governed by a convection-diffusion equation with a nonlinear boundary condition at the root surface, which is included as a boundary of the soil domain. A shape optimization problem is formulated that aims at finding root shapes maximizing P uptake.The second part of this thesis shows how we can take advantage of the recent advances of scientific computing in the field of unstructured mesh adaptation and parallel computing to develop numerical models of soil water and solute movement with root water and nutrient uptake at the plant scale while taking into account local processes at the single root scale
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Späth, Florian Heiko [Verfasser], and Volker [Akademischer Betreuer] Wulfmeyer. "3-D observations of absolute humidity from the land surface to the lower troposphere with scanning differential absorption lidar / Florian Heiko Späth ; Betreuer: Volker Wulfmeyer." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2016. http://d-nb.info/1119866715/34.
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曾志堅 and Chi-kin Tsang. "Analysis and control of organic vapours in air and determination of metals and toxic elements in fish samples by differential pulsevoltammetry and atomic absorption spectrophotometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31210995.
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Späth, Florian [Verfasser], and Volker [Akademischer Betreuer] Wulfmeyer. "3-D observations of absolute humidity from the land surface to the lower troposphere with scanning differential absorption lidar / Florian Heiko Späth ; Betreuer: Volker Wulfmeyer." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:100-opus-12904.
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Capiral, Mary Joy Josephine M. "Measurements of ammonia and nitrous oxide emissions from potato fields in Central Washington using differential optical absorption spectroscopy (DOAS), tracer dispersion, and static chamber methods." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/m_capiral_042309.pdf.
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Thesis (M.S. in environmental engineering)--Washington State University, May 2009.Title from PDF title page (viewed on May 21, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 87-91).
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Meier, Andreas Carlos [Verfasser], John P. [Akademischer Betreuer] Burrows, John P. [Gutachter] Burrows, and Thomas [Gutachter] Wagner. "Measurements of horizontal trace gas distributions using airborne imaging differential optical absorption spectroscopy / Andreas Carlos Meier ; Gutachter: John P. Burrows, Thomas Wagner ; Betreuer: John P. Burrows." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1155919610/34.
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Graves, Rosemarie Rachel. "Can a hemispherical scanning imaging differential optical absorption spectroscopy technique be used to improve understanding of the emissions, dynamics and chemistry of nitrogen dioxide in the urban boundary layer?" Thesis, University of Leicester, 2014. http://hdl.handle.net/2381/28636.
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Air quality is an international issue which has been the subject of several European directives on pollution levels as atmospheric pollutants can have significant effects on human health, ecosystems and climate change, especially at high levels. In the UK the largest sources of atmospheric pollutants are products of combustion from power generation and motor vehicles including NO[subscript x] (NO and NO[subscript 2]), CO, VOCs and particulate matter. Hence it is becoming increasingly important to measure changes in these air pollutants especially in urban areas where these pollutants are at the highest levels. Differential Optical Absorption Spectroscopy is now commonly used as an air quality tool; primarily through the measurements of nitrogen dioxide (NO[subscript 2]). CityScan is a Hemispherical Scanning Imaging Differential Optical Absorption Spectrometer (HSI-DOAS) which has been optimised to measure concentrations of NO[subscript 2]. This thesis will describe the development and subsequent deployment of three CityScan instruments and the first results from these deployments. CityScan has a 95° field of view (FOV) between the zenith and 5° below the horizon. Across this FOV there are 128 resolved elements which are measured concurrently, the spectrometer is rotated azimuthally 1° per second providing full hemispherical coverage every 6 minutes. Three CityScan instruments were built between 2009 and 2012 and deployed in various locations, including Leicester, London and Bologna. Data from one of these instruments has been validated with a MAX-DOAS instrument (TROPOGAS) and in situ monitors. The comparison with the TROPOGAS instrument produced gradient values between 0.7 and 1 with R² values rarely lower than 0.7. An NO[subscript 2] detection limit of CityScan has been calculated to be 4 x 10[superscript 15] mol cm[superscript -2]. The extensive field of view of the CityScan instruments has allowed NO[subscript 2] concentrations to be mapped on city-wide scales allowing areas of high and low pollution to be identified with a spatial resolution which has never been possible before without the use of models.
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Perez, Sira Elevina E. "Determination of the correlation between amylose and phosphorus content and gelatinization profile of starches and flours obtained from edible tropical tubers using differential scanning calorimetry and atomic absorption spectroscopy." Online version, 2000. http://www.uwstout.edu/lib/thesis/2000/2000pereze.pdf.
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Le, Rille Olivier. "Étude et validation d'un lidar hétérodyne émettant à 2 micron pour l'application à la météorologie et à l'environnement." Paris 6, 2002. http://www.theses.fr/2002PA066227.
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McIlwain, Doris J. F. "Impatient for paradise : a rites of passage model of the role of the psychological predispositions in determining differential openness to involvement in new religious movements." University of Sydney, 1992. http://hdl.handle.net/2123/2546.
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Doctor of PhilosophyThis study considers the adequacy of explanatory accounts of recruitment to New Religious Movements [NRMs], defined by their doctrinal innovation or importation from another culture, and formed around a charismatic leader. It considers the coercive persuasion paradigm [brainwashing] which assumes no predisposing features of those who become involved in NRMs and a sociological account by Snow Zurcher and Ekland-Olsen (1980) which seeks to redress overly exclusive attention to psychological variables by emphasising the importance of structural variables such as the existence of 'discretionary time' and having a friend involved in the NRM. It is suggested that a psychological focus in explaining movement involvement need not entail a de-emphasis of the relevance of current life circumstances, such as social bonds, and life stress, nor a failure to acknowledge the importance of the group's ideology in lending definition to a person’s felt difficulties. A new model of personal change is proposed, termed the Rites de Passage model, which entails the disruption, transition and reincorporation of a socially sustained sense of identity and suggests conversion can be viewed as an example of re-socialisation. The historical lineage of the model is traced from Van Gennep's (1908) anthropological work to studies of brainwashing in the work of Schein (1957) and Lifton (1961). Since the emphasis is on the profile of a seeker, specific focus is placed on the early phases of this process where disruption occurs in existing coping techniques and social supports as a result of disruptive life events, and consideration is given to other relevant precursors of movement involvement. Lofland and Stark's (1965) model forms the conceptual framework from which literature regarding differences in life stress, social bonds, prior behavioural involvement in NRMs, and prior cognitive spiritual orientation can be addressed. The work of Galanter (1980, 1989), Barker (1981, 1984), Heirich (1977) and Snow and Phillips (1980) provides substantial evidence for the existence of pre-existing differences between affiliates (who make contact with such movements) and nonaffiliates (who do not). In this thesis two facets of differential involvement are addressed: i) why does one individual rather than another become involved ii) with a given genre of movement rather than another? The Rites de Passage model proposed here, which is a modified version of Lofland and Stark's (1965) account of cult conversion, is tested placing NRMs in a comparative context with a secular self-help agency: a therapy group. People with disrupted social identities might seek movement involvement, but what distinguishes whether they seek out a secular or spiritual movement, and if spiritual – what determines the appeal of eastern or western spiritual groups? To explore these questions, four groups of affiliates to three different eastern NRMs are compared to a therapy group, (Richardson and Kilbourne, 1984), two control groups (a student sample, and a sample from the general population) and a western NRM. There are 160 subjects overall, who completed a battery of questionnaires at point of first contact with the movement, to distinguish the precursors for movement involvement from the sequelae. Exceptions to this prospective data collection were the western NRM and the inclusion of a graduate rebirthing group. The latter was deliberately included to facilitate pre-involvement and post-involvement comparisons. The former's adept status was due to the leader's reluctance to burden new members with a three hour test battery. Measures were taken regarding life events and their psychological impact using Henderson, Byrne and Ducan-Jones (1981) recent life events inventory and impact scales using a twelve month time frame. A modified version of the Interview Schedule for Social Interaction (by Henderson et al, 1981) was used to assess the availability and adequacy of acquaintance-level and intimate bonds in the recent past. Mental health was assessed using Galanter's (1980) General Wellbeing Scale and Tellegen's Multidimensional Personality Questionnaire (1982). Recollections of early family relations were assessed using Likert scales derived from the detailed comparative study by Ullman (1982) which suppported the psychoanalytic hypothesis regarding troubled early parental relations, suggesting that current life difficulties re-evoked early life problems. Since disruption is seen as a necessary but not sufficient condition for movement involvement (Greil, 1977) the therapy and eastern groups were not expected to differ from each on the disruption and loneliness measures, and they did not differ. They were expected to have experienced more disruption in greater isolation than the control groups and those already belonging to a spiritual group – namely the western NRM. The therapy and eastern NRM groups did differ from the others in these respects. The value-added form of the model merely specifies that a substrate of stress and disruption suffered in relative isolation and loneliness will increase the probability that some for of social agency will be sought. Disruption experienced in relative loneliness is the first component of differential recruitment to movement involvement, or ‘differential openness’ as it is termed here. So the brainwashing model does not hold as there are differences between those drawn to movements compared to control groups. Do personality differences contribute to which movement genre appeals? A strikingly different personality profile emerged of those drawn to eastern NRMs. Differences were predicted and found between the eastern groups on the one hand and therapy group, control groups and western group on the other, when personality variables were considered. Relevant features of the profile included: a lack of traditionalism, a challenging attitude to conventional authority (assessed by Ray's (1971) balanced F scale) and absorption - a tendency to experience perceptual phenomena indicative of an absorptive or mystical tendency (Tellegen's MPQ was used to assess this personality feature). The eastern groups have a personality profile of being: unconventional, somewhat impulsive and highly absorptive in perceptual style. This profile distinguished them from all other groups. When the additional feature of the model was considered the profile of a potential seeker was more strongly delineated: the consonance between an individual’s intensity and orientation of spiritual beliefs and the orientation of movement ideology was highly influential. This was assessed by a spiritual orientation scale [the SOS] developed by the author across three pilot studies using Coombs Unfolding Technique (Coombs, 1964) to produce a metric ordinal scale which assesses general spiritual beliefs (which underlie any spiritual worldview), eastern and western spiritual beliefs. A major finding of the study was that a markedly distinctive feature of those drawn to NRMs is a spiritual orientation consonant with that of the movement approached. The SOS revealed a strongly demarcated pre-existing eastern spiritual orientation in those drawn to make contact with Eastern NRMs, which set them apart significantly from all other groups. The Western NRM, (already members of their group) had a western spiritual orientation, to the exclusion of an eastern orientation, while the eastern groups were more eclectic. Both eastern and western NRMs were spiritually more intense on the general spiritual items of the SOS, suggesting these items are central to any spiritual worldview. All of the major predictions of the Rites de Passage model were supported. The model provides a welcome link between a sociological and psychological focus on movement involvement. The systematic differences between affiliates and non-affiliates of NRMs at point of first contact, suggest (contra contemporary brainwashing models, though not the sophisticated models of Schein and Lifton) that recruitment is unlikely to be completely due to NRM design: the results suggest participants are likely to be interested and consenting. In summary, it is shown that those drawn to New Religious Movements of an eastern kind are indeed non-traditional, have a high incidence of recent life events and suffer a sense of community isolation, and loneliness which are considered as factors which might lead a person to modify an unfulfilling lifestyle. A portrait of a seeker is lightly (sketched against a background of this dissatisfaction) which includes personality variables like an impulsive, present-oriented pleasure/pain regulatory style, being high on absorption -a mystical perceptual style, and having both an intensity and a congruence of spiritual orientation with that of the ideology of the movement approached. These are considered potential influences on the genre of movement contacted, and are suggested as explanatory of the second facet of differential openness to movement involvement. Disruption sets a person seeking; personality shapes to which appeals s/he is open. The relative privilege of the Western NRM in terms of reduced stress, availability of community and intimate social support suggests that involvement does provide a relief effect, though caution must be exercised in interpreting this difference as these groups differ in membership status and spiritual orientation. The distress and neediness of those contacting movements for the first time is apparent, which suggests that movement contact might be a response to felt dissatisfaction interpreted within a spiritual worldview. An eastern spiritual worldview is a highly significant distinguishing feature of affiliates, and is the final phase of the Rites de Passage Model. Speculative theoretical consideration is offered of the data's implications for a psychoanalytic consideration of movement involvement, in the light of Cushman (1986), Deutsch (1983), Halperin (1983) Doi (1971) and Kohut's (1977). Theory and research is adumbrated concerning differential openness to charismatic appeal.
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White, Rebekah. "A Physiologically-Based Pharmacokinetic Model for Vancomycin." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/honors/308.
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Vancomycin is an antibiotic used for the treatment of systemic infections. It is given
intravenously usually every twelve or twenty-four hours. This particular drug has a
medium level of boundedness, with approximately fty percent of the drug being free
and thus physiologically eective. A physiologically-based pharmacokinetic (PBPK)
model was used to better understand the absorption, distribution, and elimination of
the drug. Using optimal parameters, the model could be used in the future to test
how various factors, such as BMI or excretion levels, might aect the concentration
of the antibiotic.
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Mutin, Pascal. "Génération de fréquences infrarouges par mélange de lasers à colorants pulsés dans des cristaux non linéaires : application à la spectroscopie à haute résolution." Dijon, 1988. http://www.theses.fr/1988DIJOS023.
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Deux radiations de grandes finesses spectrales (6 mhz) provenant de deux lasers à colorant impulsionnels (puissances crêtes 7kw et 12 kw), ceux-ci amplifiant une longueur d'onde continue, sont mélangées dans le cristal de iodate de lithium. La fréquence générée par ce milieu est la différence de leurs fréquences et est accordable dans l'infrarouge de 1600 cm-1 à 2600 cm-1. Une première étude porte sur les caractéristiques de la source infrarouge. Du fait de la finesse spectrale de cette source (environ 6mhz),un spectromètre infrarouge haute résolution fonctionnant sur le principe de l'absorption différentielle a été conçu. Une deuxième étude rend compte des performances d'un tel spectromètre : celles-ci ont été testées sur la molécule de protoxyde d'azote.
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McCartt, Paezha M. "A Physiologically-Based Pharmacokinetic Model for the Antibiotic Levofloxacin." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/honors/343.
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Levofloxacin is in a class of antibiotics known as fluoroquinolones, which treat infections by killing the bacteria that cause them. A physiologically-based pharmacokinetic (PBPK) model was developed to investigate the uptake, distribution, and elimination of Levofloxacin after a single dose. PBPK modeling uses parameters such as body weight, blood flow rates, partition coefficients, organ volumes, and several other parameters in order to model the distribution of a particular drug throughout the body. Levofloxacin is only moderately bound in human blood plasma, and, thus, for the purposes of this paper, linear bonding is incorporated into the model because the free or unbound portion of the drug is the only portion that is considered to be medicinally effective. Parameter estimation is then used to estimate the two unknown parameters given clinical data from literature on the total concentration of Levofloxacin in the blood over time. Once an adequate model is generated, the effects of varying Body Mass Index are tested for the absorption and distribution of Levofloxacin throughout the body.
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Souza, Paulo Cesar de. "Desenvolvimento de um espectrômetro por absorção diferencial para medidas de poluentes na atmosfera." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-27052008-135818/.
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Este trabalho apresenta os resultados da construção de um espectrômetro utilizando a espectroscopia ótica por absorção diferencial (DOAS) para determinação de poluentes na atmosfera. A determinação e a quantificação de gases-traço contaminantes na atmosfera são possíveis pelo registro da transmitância, e posterior avaliação das estruturas de absorção características de cada espécie, em um caminho ótico aberto conhecido na atmosfera. As partes óticas e eletrônicas foram caracterizadas e o software de comando e processamento espectral foi desenvolvido. O sistema construído foi testado em laboratório e medidas de emissões veiculares de quatro automóveis foram realizadas. Os resultados das emissões veiculares apresentaram uma sensível diferença entre os veículos no regime de operação (motor frio e quente) por um fator que varia entre 5 e 8.This work presents the results of the construction of a spectrometer using the differential optical absorption spectroscopy (DOAS) for determination of pollutants in the atmosphere. The determination and quantification of trace gas contaminations in atmosphere is possible by recording and later evaluation of characteristic absorption structures in a known path length in open atmosphere. The parts optics and electronic had been characterized and the software of command and spectral processing was developed. The system was built and tested in laboratory and vehicle emissions measures of four cars were performed. The results in vehicle emissions showed a noticeable difference between vehicles in the system of operation (hot and cold engine) by a factor ranging between 5 and 8.
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Niccolai, Silvia. "Three-body Forces in Photoreactions on 3He." Washington, D.C : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Energy Research ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/824932-PJ4Kr6/native/.
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Thesis; Thesis information not provided; 1 Feb 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "JLAB-PHY-03-39" "DOE/ER/40150-2763" Silvia Niccolai. 02/01/2003. Report is also available in paper and microfiche from NTIS.
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Berka, Michal. "Studium chování nanočástic platiny ve složkách životního prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-413549.
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Platinum nanoparticles pose a risk to environmental compartments. The aim of this diploma thesis is to conduct research on the influence of platinum nanoparticles in a wide range of concentrations on soil properties at different humidities. Specifically, it is about influencing the stability of water molecular bridges, the content of aliphatic crystallites, the retention capacity of water in the soil and the strength of water binding. Furthermore, the amount of nanoparticles sorbed on the soil was also measured. These indicators give us more information about the influence of platinum nanoparticles on evapotranspiration and soil deterioration. Methods of thermal analysis (differential scanning calorimetry) and optical methods (atomic absorption spectrometry) were used for these researches. The theoretical part of the work is devoted to a comprehensive introduction to platinum and its nanoparticles, as well as aqueous molecular bridges. It has been found that 200 nm platinum nanoparticles affect the strength of aqueous molecular bridges, have no effect on aliphatic crystallite content, have minimal effect on soil water retention, and that the water bond strength decreases due to platinum nanoparticles at high relative humidity. With 200 nm platinum nanoparticles, complete adsorption to soil occurs over the entire concentration range. With 3 nm nanoparticles, the soil is supersaturated at higher concentrations and larger amounts are not adsorbed. The results show that the larger the size of the platinum nanoparticles, the lower the negative effect on evapotranspiration and soil function itself.
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Nitsche, Robert. "Optical Properties of Organic Semiconductors: from Submonolayers to Crystalline Films." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979835186.
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Nitsche, Robert. "Optical Properties of Organic Semiconductors: from Submonolayers to Crystalline Films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1147356837431-39487.
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We have measured the optical properties of films of the organic semiconductors PTCDA (3,4:9,10-perylene-tetracarboxylic dianhydride) and HBC (peri-hexabenzocoronene), prepared by Organic Molecular Beam Expitaxy (OMBE), on different substrates by means of Differential Reflectance Spectroscopy (DRS). The optical setup enables us to directly follow the thickness dependent optical properties of the organic films, starting from submonolayer coverage up to thicker films on the order of 20 monolayers (ML) film thickness. Due to the different optical nature of the different substrates used, i.e., mica, glass, Au(111), and HOPG, the direct interpretation of the DRS signal is not feasible. Therefore, we have proposed a method by which the calculation of the optical constants n (index of refraction) and k (absorption index) of thin films on arbitrary substrates from just one spectral measurement (in our case the DRS) becomes possible. The results fulfill a priori a Kramers-Kronig consistency and no specific model is needed to express the spectral behavior of the optical constants. Based on our method, we have successfully calculated the optical constants, and therefore the absorption behavior, of films of different thickness of PTCDA on mica, glass, Au(111), and HOPG, as well as of HBC on mica, glass, and HOPG. Extrinsic effects due to island growth or the presence of a polarizable substrate (screening) have been accounted for. We have introduced a finite dipole model which considers the extended geometry and anisotropy of the organic molecules. The calculated absorption behavior is discussed in great detail in terms of spectral changes with varying film thickness, different growth modes, degree of ordering of the films, interactions with the substrates and oscillator strength. A direct observation of a monomer-dimer transition in solid films could be observed for the first time. Our results indicate an exciton delocalization over about 4 molecules for both molecules.
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Weerasekara, Aruna Bandara. "Electrical and Optical Characterization of Group III-V Heterostructures with Emphasis on Terahertz Devices." Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/phy_astr_diss/16.
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Electrical and optical characterizations of heterostructures and thin films based on group III-V compound semiconductors are presented. Optical properties of GaMnN thin films grown by Metalorganic Chemical Vapor Deposition (MOCVD) on GaN/Sapphire templates were investigated using IR reflection spectroscopy. Experimental reflection spectra were fitted using a non - linear fitting algorithm, and the high frequency dielectric constant (ε∞), optical phonon frequencies of E1(TO) and E1(LO), and their oscillator strengths (S) and broadening constants (Γ) were obtained for GaMnN thin films with different Mn fraction. The high frequency dielectric constant (ε∞) of InN thin films grown by the high pressure chemical vapor deposition (HPCVD) method was also investigated by IR reflection spectroscopy and the average was found to vary between 7.0 - 8.6. The mobility of free carriers in InN thin films was calculated using the damping constant of the plasma oscillator. The terahertz detection capability of n-type GaAs/AlGaAs Heterojunction Interfacial Workfunction Internal Photoemission (HEIWIP) structures was demonstrated. A threshold frequency of 3.2 THz (93 µm) with a peak responsivity of 6.5 A/W at 7.1 THz was obtained using a 0.7 µm thick 1E18 cm−3 n - type doped GaAs emitter layer and a 1 µm thick undoped Al(0.04)Ga(0.96)As barrier layer. Using n - type doped GaAs emitter layers, the possibility of obtaining small workfunctions (∆) required for terahertz detectors has been successfully demonstrated. In addition, the possibility of using GaN (GaMnN) and InN materials for terahertz detection was investigated and a possible GaN base terahertz detector design is presented. The non - linear behavior of the Inter Pulse Time Intervals (IPTI) of neuron - like electric pulses triggered externally in a GaAs/InGaAs Multi Quantum Well (MQW) structure at low temperature (~10 K) was investigated. It was found that a grouping behavior of IPTIs exists at slow triggering pulse rates. Furthermore, the calculated correlation dimension reveals that the dimensionality of the system is higher than the average dimension found in most of the natural systems. Finally, an investigation of terahertz radiation efect on biological system is reported.
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Rinzan, Mohamed Buhary. "Threshold extension of gallium arsenide/aluminum gallium arsenide terahetrz detectors and switching in heterostructures." unrestricted, 2006. http://etd.gsu.edu/theses/available/etd-10102006-204618/.
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Thesis (Ph. D.)--Georgia State University, 2006.Title from title screen. Unil Perera, committee chair; Donald Edwards, Gennady Cymbaluyk, Mark Stockman, Nikolaus Dietz, Paul Wiita, committee members. Electronic text (348, 24-32 p. : ill.) : digital, PDF file. Description based on contents viewed June 8, 2007. Includes bibliographical references (p. 24-30, second sequence).
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Nguyen, Trung. "Differential absorptive capacities, ambidexterity & new product creativity : a longitudinal investigation of US high technology SMEs from the attention-based perspective." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/72668/.
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The study investigates how SMEs generate new product creativity through different means of innovation strategies and their antecedents. It examines the fundamental role of the CEO in directing a firm’s information seeking orientation, a firm’s absorptive capacities in facilitating the process of absorbing information and lastly the combination of exploitation and exploration innovations to achieve ambidexterity. To this end, to address the bottom line importance of the ambidextrous strategy, new product creativity is hypothesised to be positively related and acts as a vital bridge linking ambidexterity and financial performance. Existing literature shows limited empirical support for a firm’s ability to pursue both exploitative and explorative innovations for performance outcomes. In particular, very little is known of the ambidexterity consequence in new product creativity. Literature also lacks empirical evidence on leadership-based antecedents and understanding of how ambidexterity works in the context of SMEs. To examine the relationships, the study uses mixed methods of content analysis, econometrics and financial ratios to generate longitudinal and objective data for 148 SMEs. Seemingly Unrelated Regression is then employed to analyse and test the hypotheses. Findings show the importance of generating a high number of creative ideas by demonstrating a positive empirical link with future financial performance. It also found that given the resource impediments of SMEs, the most appropriate approach to successful new product creativity is to manage exploitation and exploration innovations sequentially. In addition, contrary to the popular view of external information driving firms’ innovation strategy, deep understanding of the firm internally may be most important. Lastly, the result proves that despite being generic in nature and having an insignificant effect in driving either exploration or exploitation separately, future focus becomes an important factor when it comes to the firm’s ability to balance innovation ambidextrously.
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Atmani, Hassane. "Investigations dans le domaine des comportements thermiques de matériaux désordonnés : application au sélénium et aux mélanges Se-Bi à faible concentration en bismuth." Rouen, 1988. http://www.theses.fr/1988ROUES009.
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Naik, Devang S. "Bose-Einstein Condensation: Building the Testbeds to Study Superfluidity." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-09072006-141453/.
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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2007.Davidovic, Dragomir, Committee Member ; Kennedy, T.A. Brian, Committee Member ; Chapman, Mike, Committee Member ; Raman, Chandra, Committee Chair ; Bunz, Uwe, Committee Member.
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Brown, David Michael Philbrick C. Russell. "Multi-wavelength differential absorption measurements of chemical species." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3098/index.html.
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Dinovitser, Alex. "A stabilized master laser system for differential absorption LIDAR." Thesis, 2012. http://hdl.handle.net/2440/81053.
Full textAbstract:
In this thesis, we present a prototype water vapour DIfferential Absorption Lidar (DIAL) instrument with accurate and precise wavelength control of master diode lasers. This stabilization system design has a number of novel elements that work towards a robust and low-cost autonomous DIAL observatory. With two continuous wave optical wavelengths stabilized, a pulse is formed using an Acousto-Optic Modulator (AOM) to switch light out of each control system to form the transmitted pulse. The control systems employ synchronous reference signal detection that suppresses system perturbations due to the optical switching, facilitating the use of deep dither modulation that aids in accurate stabilization to weak absorption lines. Furthermore, ratiometric detection in the control loop suppresses interference caused by back reflections in optical fiber components, as well as amplitude modulation of the laser diode due to injection current. In our system, the first laser is stabilized to an absorption line of a water vapour cell, while the second is beat-frequency stabilized relative to the first using a passive 16 GHz bandpass filter. This technique can be expanded to stabilize any number of reference lasers with respect to each other and to an absolute optical standard. The prototype DIAL uses a Tapered optical Amplifier (TA) to form 1 μs 500 mW optical pulses with a repetition rate of >3 kHz for atmospheric transmission. Fourteen observation experiments were conducted over two years, with water vapour measurements obtained using a calibrated humidity sensor, using three saturated salt solutions as humidity references. The measured pulse extinction was used to calculate the effective absorption cross-section of the transmitter, and therefore used to calculate quantitative water vapour measurements from the DIAL observation data. It is hoped that this work will be useful to the further development and commercialization of this unique and powerful remote sensing technique.Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2012
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Bae, Kwang-Ho. "Differential absorption lidar for water vapour in the atmosphere." Thesis, 2002. http://hdl.handle.net/2440/120379.
Full textAbstract:
Looks at the development of Differential Absorption Lidar based on diode lasers for profiling the temporal and vertical distribution of water vapour in the atmosphere. Frequency modulation spectroscopy is applied t observe water vapour absorption lines in the infrared region and the wavelength locking of the master laser to the centre of the water vapour absorption line.Thesis (Ph.D.) -- University of Adelaide, Dept. of Physics and Mathematical Physics, 2002.