A new instrument using a time-of-flight (TOF) mass filter (MF) for resonance enhanced multiphoton ionization (REMPI) studies of gas phase molecules was developed. This instrument was designed to make use of the selectivity of the REMPI process and the sensitivity of a TOF-MF with a microchannel plate detector. A pulsed valve inlet system was tested to determine its effectiveness in “cooling” molecules but it was not used for the bulk of the studies performed. The instrument was tested using molecular and atomic bromine, atomic carbon, and atomic iodine. The atomic bromine, carbon, and iodine, were generated by the photodissociation of molecular bromine, hydrocarbons, and methyl iodide respectively. Nitrogen gas in air was used to test the pulsed valve system. The instrument was then used to conduct REMPI studies of five dichlorotoluene (DCT) isomers (2,4-DCT; 2,5-DCT; 3,4-DCT; 2,6-DCT; and 2,3-DCT). REMPI studies of six dichloroaniline (DCA) isomers, including 2,5-DCA; 3,4-DCA; 3,5-DCA; 2,6-DCA; 2,4-DCA; and 2,3-DCA were conducted. Six isomers of dichlorophenol (DCP) were studied (2,5-DCP; 3,4-DCP; 3,5-DCP; 2,3-DCP; 2,4-DCP; and 2,6-DCP). It was determined that the 2,3-DCP; 2,4-DCP; and 2,6-DCP isomers photodissociated to form CCl, which itself could be observed through a REMPI process. The results from the REMPI studies of the dichloroaromatics and data from previous ultraviolet, infrared, and RAMAN studies of these molecules was used in order to assign the observed peaks. The observed 0,0 π→π* transition energies of the dichloroaromatics studied were used along with ultraviolet 0,0 π→π* transition energies from previous works in order to discuss substituent effects. A qualitative method of predicting the relative location of 0,0 π→π* transition energies of dichloroaromatics was developed.

This thesis studies the design and implementation of an ultra-sonic water depth sounder. The depth sounder is implemented in a hand-held smart console used by divers. Since the idea of echo sounding is to measure the flight time between transmitting the signal and receiving the echo, the main challenge of this task is to find a time-of-flight (ToF) estimation for a signal in noise. It should be suitable for this specific application and robust when implemented in the device. The thesis contains an investigation of suitable ToF methods. More detailed evaluations of the matched filter, also known as the correlation method, and the linear phase approach are done. Aspects like pulse frequency and duration, speed of sound in water and underwater noise are taken into account. The ToF-methods are evaluated through simulation and experiments. The matched filter approach is found suitable based on these simulations and tests with signals recorded by the console. This verification leads to the implementation of the algorithm on the device. The algorithm is tested in real time, the results are evaluated and improvements suggested. / Denna rapport behandlar skattning av vattendjup med hjälp av ultraljudspulser och implementation av detta. Djupmätaren implementeras i en handhållen dykarkonsoll. Eftersom grundidén i ekolodning är att mäta tiden mellan att pulsen skickas iväg och att ekot tas emot är en stor del av utmaningen att hitta en lämplig metod för att skatta flykttiden för en signal i brus. Metoden ska passa för detta användingsområde och vara robust. Rapporten tar upp tidigare forskning gjord inom flykttidsestimering. De metoder som utvärderas för implementation är det matchade filtret, också kallad korrelationsmetoden, och linjär fas-metoden. Andra aspekter som avvägs och utreds är pulsfrekvens och pulsvaraktighet, ljudets hastighet och brus under vattnet. Metoderna för att skatta flykttid utvärderas genom simuleringar. Det matchade filtret bedöms vara lämpligt baserat på dessa simuleringar och experiment med data inspelad med konsollen. Denna verifikation leder till att algoritmen implementeras på konsollen. Den implementerade algoritmen testas i realtid, resultaten utvärderas och förbättringar föreslås.

The use of short columns, higher carrier gas velocity and fast temperature programs in Comprehensive Two-Dimensional Gas Chromatography coupled to Time-of- Flight Mass Spectrometry (GC x GC/TOFMS) technique is expected to increase the speed of analysis up to several orders of magnitude when compared to conventional gas chromatography (GC) or gas chromatography/mass spectrometry (GC/MS). A systematic evaluation of the GC x GC/TOFMS configuration for high-speed applications has received little attention in the literature. The feasibility of High Speed Comprehensive Two-Dimensional Gas Chromatography coupled to Mass Spectrometry (High speed GC x GC/MS) for complex mixtures has been investigated in this thesis. A particular focus was placed on comparing conventional scanning quadrupole mass spectrometry (qMS) with a newly available non-scanning time-of-flight instruments (TOFMS). Experiments were carried out using GC/qMS, GC x GC/qMS, GC/TOFMS and GC x GC/TOFMS both in normal (slow) and fast temperature rates coupled with high frequency modulation in GC x GC. Initially a complex mixture consists of 24 semivolatile compounds was used as the analyte for the above purpose. In the initial experiments parameters like acquisition rate and duty cycle for qMS were determined to evaluate the effectiveness of the instrument for fast analysis. The practical duty cycle value obtained for the qMS was only about 18 % for single ion and one compound at a dwell time of 10 ms in SIM mode. In both high-speed GC/qMS and high-speed GC x GC/qMS techniques only about 40 % of the components in the complex mixture were found to be well separated. The acquisition rate of scanning instruments like qMS is incompatible for fast eluting peaks in high speed GC. TOFMS that has an acquisition rate of several hundred spectra per second offer the potential to define the fast GC peaks accurately. The high quality spectra from TOFMS also enable deconvolution of coeluting peaks in the complex mixtures. The advantage of the automated spectral deconvolution is demonstrated for the identification of the coeluting peaks in the complex mixtures. Coelution of peaks is also observed with highspeed GC/TOFMS technique. The high-speed GC x GC/TOFMS was also tested with two different analyte system ??? A pesticide mixture and platformate (an aromatic mixture) to evaluate the suitability for high-speed analysis of complex mixtures. A poor resolution was observed for the pesticide mixture in the two-dimensional plane and it appeared, as there was nearly no orthogonal separation in the second dimension. The platformate mixture displayed a better two-dimensional separation. Chromatographic peak resolution is not really a primary requirement for locating and identifying the coeluting compounds in high-speed GC x GC/TOFMS technique. However, it was observed that the high-speed GC x GC/TOFMS too faced problem to unscramble the mass spectra of those compounds with similar structure and sharing the same unique masses.

Thesis (Ph.D.)--Ohio University, March, 2005. / Includes bibliographical references (p. 163-176)

Thesis (Ph.D.)--Ohio University, March, 2005. / Title from PDF t.p. Includes bibliographical references (p. 163-176)

La dérive de pulvérisation peut être mesurée au champ ou en soufflerie. Paradoxalement, les tests au champ sont sujets à de grandes variations dues aux conditions atmosphériques mais peuvent être plus facilement réalisés contrairement aux tests en soufflerie. Ainsi les principaux modèles de dérive sont basés sur des mesures au champ alors que peu de modèles s’inspirent de mesures en soufflerie. L’objectif de ce travail a été de définir un ou des descripteurs de la dérive sur la base de l’analyse de courbes de dépôts obtenues dans la soufflerie d’IRSTEA Montpellier. Par rapport aux souffleries existantes, un protocole d’exposition de longue durée a été utilisé avec une forte densité d’échantillonnage. Un plan expérimental comprenant 99 modalités a été réalisé en tenant compte de différents types de buses (FF, AI, AI Twin jet), différente hauteurs de rampe de 40 à 80cm, différentes positions de la rampe (frontale, latérale et angles intermédiaires) et différentes vitesses de vent entre 2 et 7.5m s-1. Les résultats ont montré que le taux de dérive à 5m sous le vent (DR5) correspond au descripteur le plus robuste si l’on tient compte du large spectre de paramètres et de réglages. Des modèles de premier ordre ont été définis pour l’expression de l’effet de la vitesse du vent ainsi que de la hauteur de rampe selon le temps de vol des gouttes (ToF). Ainsi il est possible de comparer des résultats issus de conditions expérimentales différentes et de simuler l’effet de la vitesse du vent et la hauteur de la rampe pour un type donné de buse. Des mesures in situ de taille de gouttes ont confirmé la pertinence du temps de vol comme base de l’expression des résultats. / Spray drift might be measured either infield or in a wind tunnel through specific sampling strategies. Paradoxically field tests are subjected to a high variability due to the atmospheric conditions but can be more easily conducted in the absence of a wind tunnel. The result is that most of spray drift models are based on infield measurements. Conversely very few models were developed on the basis of wind tunnel measurements. The objective of this work was to define spray drift descriptors from the analysis of drift curves in IRSTEA wind tunnel. Compared to the majority of existing wind tunnels, a long duration exposure protocol was applied with a high sampling density. A large experimental plan of 99 modalities were conducted including nozzle types (FF, AI, AI Twin jet), boom heights from 40 to 80cm, boom positions (frontal, lateral, and intermediate angles) and wind velocities from 2 to 7.5ms-1. Results showed that the drift ratio at 5m (DR5) was the most robust drift indicator considering the wide range of parameters and operations conditions (wind velocity, boom height). First order models were drawn for the expression of the effect of the wind velocity and the boom height according to the droplet time of flight (ToF). As a result it was possible to compare data from different experimental conditions and to simulate the effect of the wind velocity and the boom height for a given type of nozzle. In situ droplet size measurements confirmed the relevance of the time of flight expression.

An investigation was initiated, targeting snapshot 3D image sensors, with the objective to match the speed and resolution of a scanning sheet-of-light system, without using a scanning motion. The goal was a system capable of acquiring 25 snapshot images per second from a quadratic scene with a side from 50 mm to 1000 mm, sampled in 512×512 height measurement points, and with a depth resolution of 1 µm and beyond. A wide search of information about existing 3D measurement techniques resulted in a list of possible schemes, each presented with its advantages and disadvantages. No single scheme proved successful in meeting all the requirements. Pulse modulated time-of-flight is the only scheme capable of depth imaging by using only one exposure. However, a resolution of 1 µm corresponds to a pulse edge detection accuracy of 6.67 fs when visible light or other electromagnetic waves are used. Sequentially coded light projections require a logarithmic number of exposures. By projecting several patterns at the same time, using for instance light of different colours, the required number of exposures is reduced even further. The patterns are, however, not as well focused as a laser sheet-of-light can be. Using powerful architectural concepts such as matrix array picture processing (MAPP) and near-sensor image processing (NSIP) a sensor proposal was presented, designed to give as much support as possible to a large number of 3D imaging schemes. It allows for delayed decisions about details in the future implementation. It is necessary to relax at leastone of the demands for this project in order to realise a working 3D imaging scheme using concurrent technology. One of the candidates for relaxation is the most obvious demand of snapshot behaviour. Furthermore, there are a number of decisions to make before designing an actual system using the recommendations presented in this thesis. The ongoing development of electronics, optics, and imaging schemes might be able to meet the 3D snapshot demands in a near future. The details of light sensing electronics must be carefully evaluated and the optical components such as lenses, projectors, and fibres should be studied in detail.

Abstract Light scattering diagnostics of turbid media containing both structural and dynamic inhomogeneities is currently of significant importance. One of the important directions in modern light scattering diagnostics is the development of methods for probing biological media with visible- and near-infrared radiation allowing for visualization of the biotissue structure. Optical methods for studying the biotissue structure and characterization of its optical properties are very promising and have been rapidly developing during the past decade. The present work is aimed at improving and discovering new potentials of currently existing methods of laser diagnostics of biological tissues containing both structural and dynamic inhomogeneities. In particular, the feasibilities of spatially resolved reflectometry and time-of-flight techniques for the problem of noninvasive determination of glucose level in human blood and tissues were examined both numerically and experimentally. The relative sensitivities of these methods to changes in glucose level were estimated. Time-of-flight technique was found to be more sensitive. The possibilities of Doppler optical coherence tomography for imaging of dynamic inhomogeneities with high resolution were considered. This technique was applied for the first time for the imaging of complex autowave cellular motility and cytoplasm shuttle flow in the slime mold Physarum polycephalum. The effect of multiple scattering on the accuracy of the measured flow velocity profiles for the case of single flow and for the case of the flow embedded into the static medium with strong scattering was studied. It was shown that this effect causes significant distortion to the measured flow velocity profiles and it is necessary to take this into account while making quantitative measurements of flow velocities.

Abstract This thesis deals with the developing of fibre-optic instruments for monitoring the health of civil engineering and composite structures. A number of sensors have been tested for use with different road structures, concrete bridges, fibre reinforced polymer (FRP) containers and other composite specimens, the interrogation methods being mainly based on measuring optical power and time-of-flight (TOF). The main focus is on the development of a fibre-optic TOF measurement system and its applications, but different sensing needs and fibre-optic measurement systems are also reviewed, with the emphasis on commercial devices. Deformation in a road structure was studied with microbending sensors of gauge-length about 10 cm and a commercial optical time domain reflectometer (OTDR) in a quasi-distributed fashion. The responses of the optical fibre sensors during the one-year measurement period were similar in shape to those obtained with commercial strain gauges but the absolute measurement values typically deviated by several tens of per cent. Low dynamic range, crosstalk and poor signal-to-noise ratio proved to be the main problem when measuring several successive sensors with an OTDR. In another road investigation, microbending and speckle sensors were found useful for providing on/off-type information for traffic control applications. FRP composite containers were investigated with the focus on developing a continuous monitoring system for improving yield and quality by evaluating the state of cure during the manufacturing process and for assessing damage, e.g. delaminations, during service life. Standard multi-mode and single mode fibres with a typical length of a few hundreds of metres were embedded inside the walls of containers during the normal manufacturing process, and the measurements were carried out using an optical through-power technique and an OTDR. This largely empirical investigation revealed that the coating material and its thickness have an effect on loading sensitivity and on the applicability of the method for cure monitoring. The measurement data also indicated that the end-of-curing process and the location of external damage can be determined with a distributed optical fibre sensor and an OTDR. Several versions of a pulsed time-of-flight measurement system were developed for interrogating sensor arrays consisting of multiple long gauge-length sensors. The early versions based on commercial electronics were capable of producing relevant measurement data with a reasonable precision, but they suffered especially from poor spatial resolution, low sampling rate and long-term drift. The high precision TOF system developed in this thesis is capable of measuring time delays between a number of wideband reflectors, such as connectors or fibre Bragg gratings (FBG), along a fibre path with a precision of about 280 fs (rms-value) and a spatial resolution of about 3 ns (0.30 m) in a measurement time of 25 milliseconds. By using a fibre loop sensor with a reference fibre, a strain precision below 1 με and a measurement frequency of 4 Hz can be achieved. The system has proved comparable in performance to a commercial FBG interrogation system in monitoring the behaviour of a bridge deck, while the fact that it allows static and dynamic measurements with a number of long gauge-length sensors, also embedded in FRP composite material, makes this TOF device unique relative to other measurement systems.

The successful revival of three-dimensional (3D) cinema has generated a great deal of interest in 3D video. However, contemporary eyewear-assisted displaying technologies are not well suited for the less restricted scenarios outside movie theaters. The next generation of 3D displays, autostereoscopic multiview displays, overcome the restrictions of traditional stereoscopic 3D and can provide an important boost for 3D television (3DTV). Then again, such displays require scene depth information in order to reduce the amount of necessary input data. Acquiring this information is quite complex and challenging, thus restricting content creators and limiting the amount of available 3D video content. Nonetheless, without broad and innovative 3D television programs, even next-generation 3DTV will lack customer appeal. Therefore simplified 3D video content generation is essential for the medium's success. This dissertation surveys the advantages and limitations of contemporary 3D video acquisition. Based on these findings, a combination of dedicated depth sensors, so-called Time-of-Flight (ToF) cameras, and video cameras, is investigated with the aim of simplifying 3D video content generation. The concept of Time-of-Flight sensor fusion is analyzed in order to identify suitable courses of action for high quality 3D video acquisition. In order to overcome the main drawback of current Time-of-Flight technology, namely the high sensor noise and low spatial resolution, a weighted optimization approach for Time-of-Flight super-resolution is proposed. This approach incorporates video texture, measurement noise and temporal information for high quality 3D video acquisition from a single video plus Time-of-Flight camera combination. Objective evaluations show benefits with respect to state-of-the-art depth upsampling solutions. Subjective visual quality assessment confirms the objective results, with a significant increase in viewer preference by a factor of four. Furthermore, the presented super-resolution approach can be applied to other applications, such as depth video compression, providing bit rate savings of approximately 10 percent compared to competing depth upsampling solutions. The work presented in this dissertation has been published in two scientific journals and five peer-reviewed conference proceedings.  In conclusion, Time-of-Flight sensor fusion can help to simplify 3D video content generation, consequently supporting a larger variety of available content. Thus, this dissertation provides important inputs towards broad and innovative 3D video content, hopefully contributing to the future success of next-generation 3DTV.