ABSTRACT Seven air quality basins are classified in Taiwan according to landforms¡Bweather conditions and atmosphere diffusion. The data showed that the percentages of fractional number of days that PSI is greater than 100 (unhealthful) are 11.4%, 10.5% and 15.3% in three parts of Southern Taiwan (including Kaohsiung City, Kaohsiung County and Pintung County) in the years of 1999, 2000and 2001. For Kao-Ping area alone, the percentages of unhealthful days are, 12.1% , 10.7%and 8.2% in recent three years. The air pollutants in ambient air in Kao-Ping area are particulate matter (PM10) and ozone (O3). Particulate matter (PM10) is a primary pollutant and derivative aerosol, the mainly were factory stack¡Bmobile vehicles¡Bconstruction site and emission the surface of the earth. O3 is a secondary pollutant that is generated by its precursors such as hydrocarbons (HC) and nitrogen oxides (NOx) through complex photo-chemical reactions. Accordingly, attention has been shifted to the source and control of ozone in recently years in southern part of Taiwan, instead of PM10 alone. In order to improve the air quality, the deteriorated reason and pollution condition must be understood. The purpose of this proposal is thus to identify the O3 trend variation and weather pattern and mixing height. This proposal contains two parts: Collect the meteorological data (including pressure¡Btemperature¡Bwind velocity¡Bwind direction¡Bhumidity and sunshine time) and air quality data. Then we analyze the relationship between meteorological factors and air quality. Analyze the high O3 episodes based on the characteristics of hourly¡Bmonthly and seasonally data and to investigate the effects of mixing height and Ventilation index on air quality in Kao-Ping area.

In previous studies the slotted orifice plate has demonstrated superior performance characteristics to those of the standard orifice plate. In this study, these comparisons are investigated further. The response characteristics of the slotted orifice plate to the standard orifice plate and V-Cone for two-phase flows of water and air at various qualities, flow rates, and pressures are shown visually. The effect of oil as it flows through a slotted orifice plate and standard orifice plate are visually documented. The effect of manufacturing accuracy on the slotted orifice plates is investigated as to the effect on the coefficient of discharge, percent change in pressure, and Reynolds number. The slotted orifice plate mixes two-phase flow better than the standard orifice plate and V-Cone. There is a manufacturing effect on the slotted orifice plates; the larger the area of the slots, the larger the discharge coefficient.

The mixing layer (ML) heights inferred from radiosondes, wind profilers, airborne lidar, airborne microwave temperature profiler (MTP), and in-situ aircraft data were compared during the Texas 2000 Air Quality Study in the Houston area. The comparisons and resulting good agreement between the separate instruments allowed for the spatial and temporal evolution of the ML height distribution to be determined across the Houston area on September 1, 2000. A benchmark method was created for determining ML heights from radiosonde data. The ML heights determined using this method were compared to ML heights determined using wind profiler data. The airborne lidar and MTP heights were also compared to the wind profiler heights. This was the first time the MTP was used for estimating ML heights. Because of this, the MTP heights were also compared to the ML heights determined by in-situ aircraft data. There was good agreement between the ML estimates when the instruments were co-located. The comparisons between the benchmark method and the wind profilers were independent of the quality of the profiler heights. The statistics for lidar and the wind profilers were better for the inland profiler comparisons. Even so, the results for coastal profilers were similar to the other comparisons. The results between the MTP and the wind profilers were comparable with the results found between the other instruments, and better, in that the statistics were similar for the both the inland and coastal profilers. The results between the MTP and in-situ aircraft data provided additional support for the use of MTP for determining ML heights. The combination of the inland and coastal wind profilers with the airborne instruments provided adequate information for the spatial and temporal evolution of the ML height to be determined across the Houston area on September 1, 2000. By analyzing the ML height distribution, major features were evident. These features included the shallow ML heights associated with the marine air from Galveston Bay and the Gulf of Mexico, and the sharp gradient of increasing ML heights north of Houston associated with the variation in the inversion depth found on this day.

Experiments and direct numerical simulations (DNS) have been performed to examine the e¤ects of initial conditions on the dynamics of a Rayleigh-Taylor unsta- ble mixing layer. Experiments were performed on a water channel facility to measure the interfacial and velocity perturbations initially present at the two-fluid interface in a small Atwood number mixing layer. The experimental measurements have been parameterized for use in numerical simulations of the experiment. Two- and three- dimensional DNS of the experiment have been performed using the parameterized initial conditions. It is shown that simulations implemented with initial velocity and density perturbations, rather than density perturbations alone, are required to match experimentally-measured statistics and spectra. Data acquired from both the exper- iment and numerical simulations are used to examine the role of initial conditions on the evolution of integral-scale, turbulence, and mixing statistics. Early-time turbu- lence and mixing statistics are shown to be strongly-dependent upon the early-time transition of the initial perturbation from a weakly-nonlinear to a strongly-nonlinear flow.

As the demand for oil and gas resources increases, the need to venture into more hostile environments becomes a dynamic focus in the petroleum industry. One problem associated with certain high risk formations is lost circulation. As a result, engineers have concentrated research efforts on developing novel Lost Circulation Materials (LCM’s) that will effectively treat thief zones. The most pioneering LCM’s require mixing energy to activate a reaction involving two or more chemicals. However, minimal research has been conducted to accurately predict downhole mixing capabilities. Therefore, this research focuses on developing a correlation between laboratory experiments and scaled model experiments for accurate prediction of downhole mixing energies in terms of flow rate for adequate mixing of lost circulation prevention fluids.

Mixing refers to any process that increases the uniformity of composition and is an integral part of polymer processing. The effective mixing of nanoparticles into polymers continues to be one of the leading problems that limit large scale production of polymer nanocomposites. Impingement mixing is a novel, relatively simple, continuous flow mixing process wherein mixing is accomplished by immersing a high velocity jet in a slower co-flowing stream. The resulting recirculating flow produces an energy cascade that provides a wide range of length scales for efficient mixing. An impingement mixing process was developed and studied through experiments and simulations. Numerical simulations were conducted using FLUENT to understand better the mechanism of operation of the mixer. The formation of a recirculation zone was found to affect the dispersion of nanoparticles. Results of the simulations were compared with experimental data obtained under similar conditions. While this process may be used for any polymernanoparticle combination, the primary focus of this study was the dispersion of Single Walled Carbon Nanotubes (SWNTs) in an epoxy matrix. The dispersion of SWNTs was evaluated by analyzing SEM images of the composites. The image analysis technique used the concept of Shannon Entropy to obtain an index of dispersion that was representative of the degree of mixing. This method of obtaining a dispersion index can be applied to any image analysis technique in which the two components that make up the mixture can be clearly distinguished. The mixing process was also used to disperse SWNTs into a limited number of other polymers. The mixing process is an "enabling" process that may be employed for virtually any polymer-nanoparticle combination. This mixing process was shown to be an effective and efficient means of quickly dispersing nanoparticles in polymers.

Experiments were conducted in electroosmotic flow (EOF) with 0.005≤Re ≤ 0.039 on mixing enhancement in 3-D helical microchannels. Both inlet velocity and concentration distribution along the flow channel were measurement via £gPIV and £gLIF technique respectively. The experimental results showed that the helical channels can generate nearly fully chaotic flow and achieve the complete mixing in a relatively short channel with three different helical channels (3, 4, and 6 inlet channels), and the four-inlet channel found to have the best mixing efficiency. Finally, the mixing length was correlated into a form of £f/Dh = 2.8Pe0.35 within ¡Ó8% accuracy between the experiments and prediction.

<p>                      In this study, the bioconversion of manure and silage to biogas by an anaerobic digestion process in batch reactors was studied. Biogas is a valuable alternative energy source, mainly in rural areas. The main aim for the environment is to use biogas as a fuel instead of crude oil or natural gas. In this study, two different parameters were studied to observe the changes in methane productivity. The first three reactors were shaken once per week and the following three reactors were shaken 5 times per week. The results showed that mixing has no major effect on the methane production yield. In the second six reactors a mixture of 1% and 3% silage was added and the results were recorded. When the data from the reactors with just manure was compared to the reactors with 1% and 3% silage, it was seen that the silage increased the production rate and total gas produced. The process stabilization took a long time for digestion with the 3% silage possibly caused by release of too much fatty acids.</p>

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 109-117).

Fast mixing remains a major challenge in droplet-based microfluidics. The low Reynolds number operating regime typical of most microfluidic devices signify laminar and orderly flows that are devoid of any inertial characteristics. To increase mixing rates in droplet-based devices, a novel technique is presented that uses a high Reynolds number gaseous phase for droplet generation and transport and promotes mixing through binary droplet collisions at velocities near 1m/s. Control of multiple gas and liquid streams is provided by a newly constructed microfluidic test bed that affords the stringent flow stability required for generating liquid droplets in gaseous flows. The result is droplet production with size dispersion and generation frequencies not previously achievable. Limitations of existing mixing diagnostic methods have led to the development of a new measurement technique for measuring droplet collision mixing in confined microchannels. The technique employs single fluorophore laser-induced fluorescence, custom image processing, and meaningful statistical analysis for monitoring and quantifying mixing in high-speed droplet collisions. Mixing information is revealed through three governing statistics that that separate the roles of convective rearrangement and molecular diffusion during the mixing process. The end result is a viewing window into the rich dynamics of droplet collisions with spatial and temporal resolutions of 1μm and 25μs, respectively. Experimental results obtained across a decade vi of Reynolds and Peclet numbers reveal a direct link between droplet mixing time and the collision convective timescale. Increasing the collision velocity or reducing the collision length scale is the most direct method for increasing droplet mixing rates. These characteristics are complemented by detaching droplets under inertial conditions, where increasing the Reynolds number of the continuous gaseous phase generates and transports smaller droplets at faster rates. This work provides valuable insight into the emerging field of two-phase gas-liquid microfluidics and opens the door to fundamental research possibilities not offered by traditional oil-based architectures. / text