Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Flow-tube"”.
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Experimental studies of gas phase reactions using the turbulent flow tube technique
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994.
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Applications of Proton Transfer Reaction and Selected Ion Flow Tube Mass Spectrometry in Health Monitoring
This thesis investigates the use of Volatile Organic Compounds (VOCs) in disease diagnosis and monitoring. VOCs may be found in the human body, in exhaled breath, faecal matter, urine, and skin. Analysis of the volatile profile produced in the human body can provide an indicator of metabolic …
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Evaluation of Flavor Variation in Swiss Cheese from Five Factories Using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Descriptive Sensory Analysis, and Consumer Testing
… in Swiss cheese flavor by using selected ion flow tube-mass spectrometry (SIFT-MS), descriptive sensory analysis, and consumer sensory testing. Three Swiss cheese samples were obtained from each of five different factories for a total of fifteen samples. These cheeses varied in manufacturing …
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An investigation on the variation of the pressure distribution for compressible laminar flow in a choked-flow tube due to changes of the back pressure
Thesis: B.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1961
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Studies of heterogeneous ice chemistry relevant to the atmosphere
… to be on the order of 100 nm. We found using the flow tube-CIMS technique that the presence of the QLL enhances the chlorine-activation reaction of HC1 with ClONO₂. The presence of the QLL also enhances CH₃COOH adsorption. We find that the solubilities of HC1 and CH₃COOH in the QLL are …
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Ion-molecule reaction mass spectrometry and vacuum-ultraviolet negative photoion spectroscopy
… molecules in the gas phase. Selected ion flow tube mass spectrometry has been used to study the reactions of cations and anions with ethene, monofluoroethene, 1,1-difluoroethene, trifluoroethene and tetrafluoroethene. Calculated collisional reaction rate coefficients are compared to those …
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The phase separation inlet for droplets, ice residuals, and interstitial aerosols
… an omni-directional inlet, a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube as evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosols for simultaneous sampling. Verification tests of each individual …
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Experimental investigation of the flow field during combustion in narrow circular ducts
… mixtures inside small diameter quartz tubes yielded cycles of ignition, flame propagation, and extinction. This phenomenon was studied with the intent of determining the flow structure that underlay the observed oscillatory motion. The fluid motion during the oscillations was visualized …
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Learning and recognition of hybrid manipulation tasks in variable environments using probabilistic flow tubes
… a novel representation called a probabilistic flow tube, and (2) automatically determines the relevant features of a motion so that they can be preserved during autonomous execution in new situations. I next introduce an approach to real-time motion recognition that (1) uses temporal …
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Numerical simulation of a single wafer atomic layer deposition process
… reactor consist of a warm wall horizontal flow tube, a single disc mounted halfway down the tube, and an alternating cycle flow between a reactant gas and a wash in a carrier gas. The process is governed by the desire to achieve a uniform coating on the substrate layer. Optimization is …
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Laboratory measurements and modeling of trace atmospheric species
… to expand its versatility. Firstly, a discharge flow tube was coupled with the ICLA Spectrometer, and the formation kinetics of nitrosyl hydride, HNO, were measured as a means to test the system. Secondly, a novel edge-tuner was introduced as a means to expand the spectral range of the ICLA …
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Trace Gas-Induced Brine and Disordered Interfacial Layers on Ice
… technique ellipsometry and (ii) a coated wall flow tube (CWFT) reactor, both coupled with chemical ionization mass spectrometry (CIMS) detection of HNO_3 in the gas phase. Our ellipsometry results show that exposure to HNO_3 induces surface disordering on ice at a range of environmentally …
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Measurement of Proton Transfer Reaction Rates in a Microwave Cavity Discharge Flowing Afterglow
… the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially separated from the flow tube, eliminating many of the problems inherent with the original FA devices. In addition to …
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Role of Water in the Formation, Transformation and Fate of Secondary Organic Aerosol
… sulfate seed particles was investigated using a flow tube reactor. Under constant environmental conditions, particle-phase water was found to have the largest effect on the amount of SOA formed where this additional organic material was highly oxidized, likely arising from enhanced uptake of …
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Acoustic measurements of flowing and quasi-static particulate suspensions
Flowing suspensions of solid particles in gas can be found in various industrial applications, as a method for transporting powdered solids (known as "pneumatic conveying"). The problem of measuring the mass concentration of the solid fraction has not yet been satisfactorily resolved. This thesis …
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Conceptual design for a re-entrant type fuel channel for supercritical water-cooled nuclear reactors
… The Re-Entrant fuel-channel consists of three tubes, the inner tube (flow tube), pressure tube and an outer tube. The fuel bundles are placed in the inner tube. An annulus is formed between the flow and pressure tubes, through which the primary coolant flows. A ceramic insulator is placed …
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Aqueous Atmospheric Species, a Dual Study: 1. Comparison of the Effects of Temperature, Oxygen Level, Ionic Strength, and pH on the Reaction of Benzene with Hydroxyl Radicals at the Air-water Interface to the Bulk Aqueous Phase. 2. Determination of Carbonyl Compounds in Fog Water Samples via Online Concentration and HPLC
… in both a bulk-phase reactor and a thin film flow-tube reactor as a laboratory study. For both reactor systems, temperature, pH, ionic strength, and the concentration of oxygen were varied to simulate fog event conditions. Using the thin-film reactor, in particular, has the advantage in that …
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Investigation of the Photoenhanced Reduction of Nitrogen Dioxide (NO2) on Organic Films and Above Soils as the Missing Source of Daytime Tropospheric Nitrous Acid (HONO)
… organic films using a wetted-wall flow tube (WWFT) photoreactor. Experimental methods are discussed in detail. A time-dependent model for non-equilibrium conditions incorporating both the chemistry and diffusion for predicting a best-fit reaction probability, ɣbest-fit, as a …
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Adsorption and photochemical transformation of polycyclic aromatic hydrocarbons on atmospheric water films
… of gas-phase PAHs were studied in a flow-tube photo-reactor with a view to understanding the behavior of gas-phase PAHs occurring in thin water films such as those of aerosols and fog. Naphthalene and phenanthrene were chosen as model PAHs for this study. Bulk water-air and …
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An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory
… a broad range of experiments based on an aerosol flow-tube system to probe the interactions between atmospherically relevant aerosols with trace gases. This apparatus was used to obtain simultaneous optical and size distribution measurements using FTIR and SMPS measurements respectively as a …
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