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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Characterization and Improvement Strategies of Mobile Source Air Quality Monitoring Station¡V Using Kungkuan Station of Miaoli as An Example

Chen, Chang-Jeong 17 February 2005 (has links)
ABSTRACT It is important to improve ambient air quality by reducing the emission from mobile sources. In order to investigate the characteristics of mobile sources, the statistic of traffic flow and the measurement of suspended particles were conducted in the Gonguan air quality monitoring station of Miaoli County in this investigation. Through chemical mass balance (CMB) receptor model and backward trajectory model, the location and contribution of emission sources were further identified. Accordingly, the improvement strategies for mobile sources were further proposed to improve local ambient air quality. In order to know the traffic flow variability of motor vehicles, passenger cars, motorcycle, heavy-duty diesel trucks, and buses were recorded every 15 minutes by a video camera for both weekend and weekdays. In the meantime, TSP and PM10 were simultaneously collected with high-volume samplers. The metallic content and water-soluble ionic species of particulate matter were analyzed with an inductively coupled plasma-atomic emission spectrophotometer (ICP- AES) and an ionic chromatography (IC). Chemical composition of suspended particles was then be used for source apportionment with the CMB model. Finally, the improvement strategies for mobile source management were further proposed through the correlation of traffic flow and vehicle emission rate. The results showed that the PM10/TSP ratios of suspended particles collected at the rooftop of a four-floor building was higher than those sampled at the air quality monitoring station for all quarters except the third quarter. PM>10 is the main factor for the concentration difference of suspended particles sampled on the rooftop of the building as well as at the monitoring station. Results from traffic flow records showed that passenger cars were the major source contributing greatly to the traffic flow, while no significant variation of buses was observed in the traffic flow. The linear regression of PM>10 concentration and vehicles for different wind directions (i.e. northwest, southwest and northeast) was undertaken. The results showed that, when the winds were blown from the northwest and southwest, the determination coefficients (R2) of the regression were 0.1226 (passenger cars), 0.4821 (motorcycles), 0.1014 (heavy-duty trucks), 0.3113 (buses), and 0.1919 (total traffic flow) respectively. It was 0.6140 (passenger cars), 0.6227 (motorcycles), 0.7761 (heavy-duty trucks), 0.2111 (buses), and 0.6309 (total traffic flow), respectively, for the northeast winds. It concluded that the traffic flow has significant influence on the concentration of suspended particle at the downwind sites. Among the vehicles, heavy-duty trucks played a key role. Consequently, reducing truck flow has to be paid more attention for the improvement of ambient air quality. During the sampling period, Ca, Fe, and Al were the most abundant metals of suspended particles, while Mg, K, Zn, and Cu ranked the second. Besides, the metallic contents of suspended particles sampled at the rooftop were generally lower than those collected at the monitoring station. It suggested that street dusts had major contribution to Gonguan air quality monitoring station. Among the water-soluble ionic species, sulfate (SO42-), nitrate (NO3-), and ammonium (NH4+) were major anions, converting mainly from SO2, NOx, and NH3. The results showed that the metallic contents in the second quarter were higher than that in the fourth quarter. However, an opposite trend was observed for anions. The Back Trajectory Model and CMB were applied to analyze the suspended particle. The results showed that the seasonal variation of air pollutants was also affected by the monsoon. Though air pollutants emitted from the nearby waste incinerators and industrial districts could be transported to the sampling site, resulting in unavoidable influence on suspended particles, tail gas and fugitive dusts emitted from vehicles were the most important sources contributed to the ambient air quality. The results indicated that motor vehicles were the major source of ambient suspended particles on the road sites. Therefore, the reduction of traffic emission should be the first step of the improvement strategies for ambient air quality. Especially, the emission of road dusts resulting from the drive-through of heavy-duty trucks should be paid more attention. This study proposed two strategies for improving ambient air quality: one for raising the road serving level and the other for reducing vehicles on road at the traffic crowd section. After the road serving level was improved, the TSP, NOx, CO and THC were respectively decreased about 41, 5,765, 316, and 62 g/day. The concentration of TSP, NOx, CO, and THC was respectively decreased about 95.66 £gg/m3, 38.59 ppb, 1.93 ppm, and 1.90 ppm. After carrying out special vehicle on the road control strategy, TSP, NOx, CO, and THC could be respectively decreased about 2,136, 19,291, 169,843, and 3181g/day. The concentrations of TSP, NOx, CO, and THC were respectively decreased about 96.03 £gg/m3, 52.25 ppb, 2.05ppm and 1.69ppm.. Thus, ambient air quality can be effectively improved if the heavy-duty trucks can be controlled during the rush hour. Furthermore, a substitute road for heavy-duty trucks is another option for the improvement of ambient air quality.
52

The Combined Influence of Tides and Waves on the Benthic Boundary Layer

Li, Chia-na 13 July 2005 (has links)
Continental shelves connect land and the ocean and also play a major role through time in the storage and re-distribution of terrigenous sediments to the ocean. Most of the sediments which origin in land and very shallow waters are deposited on the continental shelf. Sediment entrainment and movement in the coastal ocean are dominated by the combined effect of waves and currents within the benthic boundary layer. Our study intends to examine the relation between currents, waves and acoustic echo intensity in a wave-current boundary layer. The site of the study was located southeast off Kaohsiung Harbor entrance in southern Taiwan on the inner shelf. Between April 16 and May 1, 2004, a tetrapod was deployed with an upward-looking ADCP (Aquadopp Profiler), a CTD with an OBS (XR-420). Another downward-looking ADCP was mounted at 2 m above bed (mab). The interval of the data collection was one hour. Water samples were pumped in seven time-segments (4 in the neap tide, 3 in the spring tide) through the experimental period at 1 and 0.5 mab, respectively for suspended sediment concentration (SSC) analysis in the laboratory. Aquadopp Profiler not only records 3-D current data but also measures the echo intensity (EI). The echo intensity is proportional to the amount of backscattering particles in the water column. The acoustic intensity could be a useful reference for the total concentration of the suspended particles. Our preliminary findings indicate strong tidal control on the dynamics of suspended particles in the benthic boundary layer. The wave field is also modified by the tidal. The form number of the observed tides is 1.87, which indicates mixed tides with a predominantly diurnal component. The data were analyzed using empirical orthogonal (eigen) function (EOF) analysis. The results indicate that the tidal current dominated the alongshore current. Its period is 24.67 hours. The echo intensity are dominated by the current shear velocity. The observations show that the maximum thickness of wave boundary layer and wave-current boundary layer at the experiment site is about 0.9 cm and 1.24 cm respectively. Cross-correlation analysis results among the roughness length, the thickness of wave boundary layer, and the thickness of wave-current boundary layer show that the roughness length correlates negatively to the thickness of both boundary layer. The data were analyzed by spectrum analysis. The results indicate that wave boundary layer were dominated by the low frequency current. The wave-current boundary layer and the roughness length were dominated by the semidiurnal tides.
53

Physicochemical Characteristic Analysis of Atmosphere Suspended Particles in the Heavy Industry Peripheral Area

Chou, Yu-kuang 09 September 2009 (has links)
Kaohsiung city for the south Taiwan industry strategic place, the Siaogang area is a heavy industry stands in great numbers the area, the rendering plant, the steel plant, petrifies the factory, the incineration plant, the shipyard, the airport and so on, moreover also has transport means and so on the container truck, carriage vehicle, airplane, The air quality fraction defective occupies crown of the whole city. Kaohsiung important empty unclean control key of suspended particulate pollution, This research is for the purpose of discussing Physicochemical characteristic analysis of air suspended particles in the heavy industry peripheral area, understood in the heavy industry peripheral area air the suspended particles pollutant originates. Physicochemical characteristic analysis discussion atmosphere pollutants to influence Siaogang area. This research in May 2009 period picks each time continual sampling 24 hours to carry on each week twice sampling respectively, the East, West, South and North central area average in the Siaogang area 5 points, altogether gathers 20 samples. Another gathers motorcycle/automobile/diesel car/boiler/voltaic arc boiler/fritting furnace/road dusts different of samples, altogether 14 samples. This research uses air sampling instrument (GAST) carries on the sampling to air of the Siaogang area. Using the scanning type electron microscope (Scanning electron microscope, SEM) and instruments and so on XRD (X-ray Diffractometer, XRD) carry on the metallic element and the physicochemical characteristic analysis. The time can of because of the Siaogang area atmosphere in the suspended particulate matter origin type and the contribution quantity, relevance of in order to help control of air suspended particles in the heavy industry peripheral area pollutant and the source of pollution. This research the main of purpose this study by under construction in the air in the surrounding areas of heavy industry in the pollutants of sampling technology, and discussion of pollutants by the scene size distribution and inorganic salts, and so particulate surface characteristics and analysis for the structure and composition. This research also use a variety of discussion on the valuable instrument analysis to peripheral areas of heavy industry in the pollutants in air of surface and microstructure characteristics, the result of the above analysis, may further in-depth understanding of the heavy industries in peripheral areas of pollutants characteristics, also took granular than in the air pollutants and other kinds of granular pollutant emission sources and physicochemical characteristics of the apparent, discussion of heavy industry in peripheral areas of major sources of granular pollutants for source decrement measures. Future expected completion of roads, schools, residential, farmland, rivers the downwind side of the land of bare ground, farming, construction site River dust, straw, dead wood, rubber, PVC plastic, PE/PP plastics non-heavy industry surrounding area of micro photo, composition and organizational analysis, and than the judgment against a database of all particulate sources.
54

Field observations of linear transition ripple migration and wave orbital velocity skewness /

Crawford, Anna M., January 2000 (has links)
Thesis (Ph.D.), Memorial University of Newfoundland, 2000. / Bibliography: leaves 91-100.
55

Autonomous suspended load operations via trajectory optimization and variational integrators

De La Torre, Gerardo 21 September 2015 (has links)
Advances in machine autonomy hold great promise in advancing technology, economic markets, and general societal well-being. For example, the progression of unmanned air systems (UAS) research has demonstrated the effectiveness and reliability of these autonomous systems in performing complex tasks. UAS have shown to not only outperformed human pilots in some tasks, but have also made novel applications not possible for human pilots practical. Nevertheless, human pilots are still favored when performing specific challenging tasks. For example, transportation of suspended (sometimes called slung or sling) loads requires highly skilled pilots and has only been performed by UAS in highly controlled environments. The presented work begins to bridge this autonomy gap by proposing a trajectory optimization framework for operations involving autonomous rotorcraft with suspended loads. The framework generates optimized vehicle trajectories that are used by existing guidance, navigation, and control systems and estimates the state of the non-instrumented load using a downward facing camera. Data collected from several simulation studies and a flight test demonstrates the proposed framework is able to produce effective guidance during autonomous suspended load operations. In addition, variational integrators are extensively studied in this dissertation. The derivation of a stochastic variational integrator is presented. It is shown that the presented stochastic variational integrator significantly improves the performance of the stochastic differential dynamical programming and the extended Kalman filter algorithms. A variational integrator for the propagation of polynomial chaos expansion coefficients is also presented. As a result, the expectation and variance of the trajectory of an uncertain system can be accurately predicted.
56

SEASONAL VARIABILITY OF TOTAL SUSPENDED MATTER IN MINAS BASIN, BAY OF FUNDY

Tao, Jing 05 July 2013 (has links)
Total suspended matter (TSM) concentrations were derived from ocean colour imagery (MERIS data) in Minas Basin. Analysis of time series of TSM in 1-km2 pixel boxes throughout the Basin revealed an annual cycle in TSM in most parts of the Basin. Higher TSM of up to 85 g/m3 was observed in late-winter (February - March), and lower TSM of 5-10 g/m3 characterized late-summer (July - August). The largest annual variation occurred in the centre of Basin, and the smallest variation occurred in shallow areas. Satellite-derived TSM were compared to predictions using the Delft3D model. Increasing model erosion rate in winter relative to summer was necessary to improve agreement between model and satellite-derived TSM. In comparison with the satellite-derived estimates, the model underestimated TSM in shallow areas in summer and overestimated it in winter. This discrepancy is likely due to inaccurate satellite-derived TSM in shallow, high concentration areas of the Basin.
57

An investigation into the suspended sediment flux and dynamics of the Mgeni Estuary, Durban.

Abed, Rohaida. January 2009 (has links)
This dissertation focuses on both a hydrodynamic and geomorphological study of the Mgeni Estuary. Within the hydrodynamic study, the channel discharge, suspended sediment fluxes and estuary bed sediment characteristics and dynamics were established. Within the geomorphological study, cross-shore topographical surveying of the lower estuary region, measurement of slope angles and surface sediment characteristics were established. The results of this study illustrate strong seasonal variability. Maximum channel discharges, suspended sediment concentrations and fluxes occur during the summer months, as a result of large amounts of rainfall. Furthermore, maximum suspended sediment concentrations and fluxes occur during spring tides, as a result of a greater tidal range, which enhances bed sediment re-suspension via concomitant increased turbulence. Generally, maximum fluxes occur along the flood tide and ebb tide, during spring tides and neap tides, respectively, which suggest that the estuary is a sink for marine sediment during spring tides and an exporter of sediment during neap tides. The estuary bed sediments are very well sorted and predominantly classified as near-symmetrical, as a result of strong tidal currents that constantly transport and re-work the sediments. On average, the bed sediments are medium sand and in all probability are largely derived from the marine environment. Estuary bed sediments contain negligible mud and organic contents, which as research suggests, is common in such highenergy estuary mouths. Apart from the seasonal variability, the survey profiles and surface sediments illustrate alongshore and cross-shore variations. The profiles become flatter and finer from the Beachwood Mangroves section of the barrier towards the estuary mouth in the south, as a result of sheltering due to the engineered groyne, conforming to Bascom (1959) and Komar’s (1998) sheltered and exposed coasts concept. The survey profiles conform to the summer and winter profiles put forward by Dardis and Grindley (1988). The winter profiles consist of higher, distinct berms and berm crests, as well as vertical erosional faces, whilst the summer profiles are lower, flatter, and consist of unclear berms and berm crests. Sediments are coarsest along the lagoonward slope and finest within the estuary. A strong, positive correlation was generated between slope angle and mean grain size. Despite the low organic contents, the estuary sediments consist of the highest values of organic matter, with the beach and barrier sediments displaying negligible amounts. Thus, the Mgeni can be classified as a very dynamic and active zone. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.
58

The use of constructed wetlands for the treatment of urban runoff

Scholes, Lian N. L. January 1999 (has links)
In 1995, the Environment Agency for England and Wales developed urban runoff treatment wetlands at two selected locations in Outer London. The systems have been monitored for a wide range of parameters including heavy metals, suspended solids and BOD over a period of two years. Seven storm events were also monitored. The ability of micro-organisms, isolated from the rhizosphere of wetland plants collected at both systems, to tolerate and accumulate heavy metals has also been investigated. This study has demonstrated that constructed wetland treatment systems are capable of reducing the pollutant loadings associated with urban runoff, and that such systems can be successfully established within urban areas. During dry weather, pollutant concentrations and loadings were typically low and associated removal efficiencies highly variable. However, during storm events, pollutant loadings increased and removal efficiencies improved, with mean removal efficiencies of 71% for Pb and 81% for Cr at the Dagenham wetland. An exception to this was for suspended solids which showed an overall increase of 99% during storm events. Several design and operational issues have been identified and addressed during the course of the monitoring programme, and recommendations for the improved design and operation of urban runoff treatment wetland systems have been made. A range of micro-organisms, isolated from both wetland systems, were able to tolerate elevated Zn and Pb concentrations. Two strains (Beauveria bassiana and Rhodotorula mucilaginosa) were selected for further work. Both strains could accumulate Zn and Pb, with B. bassiana showing a high capacity to bind Pb (maximum concentration of 136mgPb/g cells dry weight). Comparison of the growth of B. bassiana at 4°C and 30°C suggested that processes of microbial metal accumulation may occur throughout the year in treatment wetlands. The presence of Pb inside hyphae of B. bassiana, associated with hyphae walls and in the surrounding medium was confirmed. This study has found that micro-organisms isolated from urban runoff treatment wetlands can tolerate and accumulate Zn and Pb, and the application of these results to wetland treatment processes is discussed.
59

Hydromorphology of within-channel river benches

Vietz, Geoffrey John January 2008 (has links)
The fluvial morphology of a river channel is a function of the river’s hydrologic and sediment regime. Within-channel river benches are a fluvial feature widely identified in the international literature as geomorphically and ecologically important. Despite this recognition the relationship between bench morphology and the flow regime is poorly understood. The aim of this thesis is to identify the components of the flow regime responsible for the formation and destruction of within-channel benches. / Opinions on the formative flows for benches are highly varied with reports that benches are formed by flows which just inundate the bench; to low-flow periods and sub-bankfull flows; bankfull flows and the annual flood; and moderate, medium and catastrophic sized floods. A large body of research also treats benches as a static morphology. Opinions on destructive flows are similarly varied. There is little empirical evidence for these suggestions. / A bench is most commonly referred to as comprising a horizontal (planar) surface which results from within-channel deposition, but the term is also used to describe bars, floodplains and erosional features. The inability of researchers to agree on the relationships between bench morphology and river hydrology is influenced by the lack of a consistent definition and classification for benches. To adequately address the aim this thesis is presented in two parts: Part A addresses bench nomenclature and provides a sound basis for Part B which addresses the processes of bench formation and destruction. (for complete abstract open document)
60

The waiting room: an art investigation of site in abeyance

Vickers, Sharon Unknown Date (has links)
This art project explores issues of unoccupied space. In particular, the project concerns itself with temporal aspects of site and issues of past, present and potential usage. This space, otherwise inert, invites activation by the spectator's psychological projections. This projected occupation calls on redolence of the past, memory and a sense of the utility of the site.Based on imagery evidence and personal remembered experience, the spectator provides context forthis site. The project uses the painting process to open up areas of sensibility around personal and remembered experience.The thesis is constituted as practice-based work, 80%, accompanied by an exegesis, 20%.

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