Large scale power generation commences with the combustion of coal or other fuel, which in turn converts high pressure water into steam which then drives a turbine thus generating electricity. Burning high moisture coal, such as lignite, for power generation implies that a significant amount of energy is wasted in vaporising the moisture, which could otherwise be used in the steam raising process. This implies that more moist coal would be required to drive the same process than if the coal was drier, thus increasing the amount of combustion products such as greenhouses gases. Introducing a dried coal in an existing boiler will significantly change the heat flux profiles, which could result in boiler damage or excessive fouling. Flame temperature is influenced by the supply of reactants; in most cases the limiting reactant will be oxygen. The supply of oxygen (through air) to a pneumatically transported coal stream and subsequent reaction is controlled by the localised fluid mechanics or ‘mixing’. This research aims to provide an understanding of the mixing process between the pneumatically transported coal and air in brown coal fired boilers by modelling the individual jets. The effects of the change in velocity ratio for the air (secondary) jets and fuel (primary) jets of rectangular burners typical of those found in brown coal fired boilers has been studied experimentally and is reported in this thesis. In particular, scientific analysis was used to investigate the physical mechanisms which control fuel-air mixing, and to quantify the concentration of primary and secondary fluid. The concentration data was used in a regression model in conjunction with a reactive combustion model, developed from a 1:30 scale cold model of the Yallourn W’ stage 2 boiler, in order that overall boiler performance can be assessed. This overall study is fundamental as a result of the questions raised concerning the future of brown coal in modern society. A qualitative flow visualisation study of the unconfined 1:30 scaled primary, and two adjacent rectangular jets, was conducted using single colour planar laser induced fluorescence. The characteristics of the jet flow were examined by imaging individually seeded primary and secondary jets and were visualised through four different planes longitudinally, on the axes of each jet. In addition, a transverse qualitative and quantitative study on the rectangular jets was also conducted for the individually seeded jets, and was visualised through planes of flow perpendicular to the direction flow, specifically at axial stations of x/D =0.1, 0.2, 0.5, 1, 2, 4, 6 and 8. The flow characteristics were also examined under different co-flow conditions, particularly secondary to primary jet velocity ratios (λ) of 0, 0.55, 1.4, 2.8, 3.6 and ∞. This quantitative data yields the basis for a 3D regression model to predict fuel-air mixing in actual boilers. A semi-quantitative investigation into some geometrical modifications on the rectangular jets was also conducted at velocity ratios of λ=0, 0.55 and 1.4. The rectangular nozzles were fitted with base plates orientated at 90 degrees and 60 degrees to the direction of flow. The longitudinal flow visualisation study highlighted the effect of velocity ratio on the flow field of the primary and secondary jets. In particular it showed that the main structures of the primary and secondary jets are sensitive to the co-flowing conditions. The primary jet also experienced the formation of coherent structures close to the bluff body re-circulation region for λ>2.8. The quantitative transverse analysis of the rectangular jets showed that the primary jet and secondary jets close to the nozzle exit plane distorted with a change in co-flowing conditions. The primary jet experienced distortion for λ>1.4, and the secondary jets experienced distortion for λ <1.4. A plausible mechanism for this “distortion” can be explained by different co-flowing conditions altering the velocity gradients of the jet, thus changing the denomination of the counter rotating vortices present in the corners of rectangular jets, allowing them to alter jet shape. The transverse quantitative analysis of the rectangular jets allowed for graphical representation of the normalised concentration of the primary and secondary jets in the radial direction and the centreline mixture fraction decay. The analysis of the latter showed that the primary jet, under all co-flow conditions, reached self-similarity at approximately x/D =4, whereas the secondary jets did so at x/D =2. The primary jets observed greater rates of centreline dilution at high velocity ratios, whereas the secondary jets did so at λ=0.55. The quantification of the centreline concentration decay obeyed the inverse rate law for all co-flowing conditions. The first order decay constant K₁, was found to be heavily dependant on velocity ratio. The planar transverse quantitative data of the primary and secondary jets was used with the method of weighted squares to develop a regression model that would three-dimensionally reproduce the scalar mixing field as a function of velocity ratio. The regression model reproduces scalar quantities for λ=0 and λ=0.55 to 3.6 for the primary jet and λ=0.55 to 3.6 and ∞ for the secondary jet, and is capable of predicting primary and secondary bulk fluid concentrations within 30 to 40 % of the measured values. A sensitivity analysis on the regression model revealed that it is highly responsive to the momentum-controlling region between the jets with a change in velocity ratio. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297627 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2007

Catalytic combustion provides us an efficient approach for the utilization and mitigation of methane, the major component of natural gas as well as an important greenhouse gas in global warming. From the research of catalytic combustion of methane, better understandings as well as solutions to the current methane-related problems can be obtained. This study investigates lean methane combustion on palladium-based catalysts. Catalysts activities were tested through ignition and extinction experiments. Several pretreatments and their influence were studied. Instrumental neutron activation analysis (INAA) and x-ray diffraction (XRD) were used as characterization tools for the catalysts. It was found that after being reduced, catalysts had stable and excellent abilities for methane conversion. However, these abilities were strongly compromised by additional water in the feeds. XRD results, combined with other testing results, implied that reduction produced the most active samples, while INAA revealed the real Pd concentrations of these catalysts. / Chemical Engineering

An interaction by exchange with the conditional mean (IECM) micromixing model is coupled to a three-dimensional single-particle Lagrangian stochastic (LS) model to estimate concentration fluctuations in plumes of a passive (i.e., non-buoyant), non-reactive (i.e., no chemistry) tracer dispersing from a variety of source configurations in four neutrally stratified flows: a horizontally-homogeneous wall shear layer flow; a horizontally-homogeneous representation of the Tombstone canopy flow; a three-dimensional inhomogeneous representation of the Tombstone canopy flow; and a three-dimensional inhomogeneous representation of the Mock Urban Setting Trials (MUST) canopy flow. The IECM micromixing model incorporates the combined effects of turbulent and molecular mixing on particle concentration. This allows the numerical estimation of all moments of the scalar concentration field, which is a significant advance over traditional LS models given that concentration fluctuations are a ubiquitous feature of a dispersing plume. The single-particle implementation of the LS-IECM model is based upon a previously reported implementation that used simultaneously computed particle trajectories to estimate the conditional mean concentration field [Cassiani, M. A., Franzese, P. A. and Giostra, U. A.: 2005, A PDF micromixing model of dispersion for atmospheric flow. Part I: development of model, application to homogeneous turbulence and to a neutral boundary layer, Atmospheric Environment 39, 1457-1469]. The model used in this thesis pre-calculates the conditional mean concentration field with an LS model for use with the IECM model, which runs as a separate simulation. The principal advantage of this single-particle approach is the performance increase on parallel computer architecture, which scales directly with the number of processors. The simulations presented in this thesis go beyond those performed with the previous model by considering three-dimensional inhomogeneous flows, as well as one-dimensional horizontally-homogeneous flows. The accuracy of the LS-IECM model was good for the flows with horizontal-homogeneity, and comparable to the results of previous simulations from older models. Rogue velocities in the simulations utilising inhomogeneous flow statistics resulted in acceptable to poor accuracy in these simulations. Suggestions for improvements to the model are made.

This research aims at evaluating a new ventilation concept: personal displacement ventilation (PDV) for improving indoor air quality. The new ventilation method combines room displacement ventilation with task ventilation, the latter being directed at controlling air quality and comfort in the microenvironment where the building occupant is working, with the premise that such directed ventilation will maintain air quality where it matters. This approach could lead to improved ventilation system design that could even provide individual control of indoor microclimate. The effectiveness of PDV was studied by using computational fluid dynamics (CFD) modeling and rigorous validation experiments. First, a small office setup was built in a controlled environmental chamber. Three PDV cases with different locations of contaminant source and one general displacement ventilation (DV) case were investigated. Spatial distributions of airflow, temperature, and hypothetical pollutant distributions were measured. The measured data were then used to evaluate the performance of PDV against defined indoor air quality and thermal comfort criteria, and to validate the CFD model. The validated CFD program was further used to study PDV under various conditions. This study found that basic equipped PDV acts no different from DV from airflow pattern?s point of view. Due to the lack of heat generation around occupant?s legs, local buoyancy effect is not strong enough to attract supply air, which is generated from diffuser nearby, to join in the plume around occupant. However, auxiliary activities adjusting the direction of supply air and adding high panels around person can improve the fraction of supply air to join the plume around person or decrease the average contaminant concentration in breathing zone.

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Even though the sleep apnea breathing occurs during the sleep,but it also affects the daytime's physiological status.Since sleep apnea breathing increases the risk of getting cardiovascular diseases,sleep disordered breathing has attracted significant amount attention.Conventional diagnosis processes for sleep disorder breathing is complex and time-consuming,therefore many efforts have been made in developing simplified physiological signal feature to detect sleep disorder breathing.To simplify the process of diagnosis,this study uses the ECG signals to differentiate patients and healthy subjects.In addition to traditional HRV features,this study also test a newly proposed ECG feature called degree of spectrum concentration which characterizes the degree of periodicity of the ECG waveform. Our experimental results show that sleep apnea patients have higher degree of spectrum concentration than healthy subjects.This work also tests the mutliscale entropy of this degree of spectrum concentration signal.The results demonstrate that complexity of the degree of spectrum concentration signal of the patients is higher than that of the healthy subjects.Finally,our results also detect differences between different age groups.

Lubrication is the lifeblood of mechanical device during the operating conditions, so that the lubricating oil detection becomes one of an important modern technology. The operator can be as early as possible to know whether the abnormal wear occurs by detecting concentration of ferrous debris in the lubricating oil. Detecting the viscosity of lubricating oil can also allow the operator to monitor the deterioration degree of lubricating oil due to environmental factors, in order to ensure whether the lubricating oil losing its effectiveness. Our laboratory previously developed a prototype of integrated apparatus for detecting the concentration of ferrous debris and the viscosity of lubricant in a single process. This study focuses on improving this prototype, so that the apparatus possesses a LCD displayer and commercialization. The design of the integrated apparatus contains a sampling unit, a measurement unit of the ferrous debris concentration, a measurement unit of the viscosity, a data acquisition system, and LCD displayer panel. In measurement unit of the ferrous debris concentration, Hall IC is used as a sensor to measure the concentration of ferrous debris by detecting the change of magnetic flux density between the magnetic poles due to the stacking of ferrous debris. In the measurement unit of the viscosity of the lubricating oils, the piston is used to squeeze the oil into the tank to measure the viscosity by detecting the load. These two units are integrated into a measuring device, and there is no interference between the values measured by the Hall IC and the load cell. Finally, these two signals are fed to a personal computer for data analysis to obtain the concentration of ferrous debris and the viscosity of lubricant. Consequently, the operator can directly observe the measured results.

The positions of high stress concentration in a bicycle frame structure made in composite materials and a way to strengthen them were investigated via SolidWorks and ANSYS, 3D picture plotting software, and numerical simulation software, respectively. The capability of productivity will be improved indirectly due to the shortening of the time in the process of customers¡¦ order, research, development and mass production. In experiment, prepreg tape (TOHO UT500 carbon fiber/AD. Group matrix) which were produced by AD. Group were made into laminates by hot-pressing machine. The material constants of the laminate and the stress-strain diagram were obtained according to the stander of ASTM D3039. The received material constants are E11 =151.55 GPa and E22 = 7.654 GPa, respectively. In simulation, the experimental data E11 and E22 were used in the numerical analysis, and obtained the stress and deformation fields of the bicycle frame structure and the front fork were plotted based on the standards provided by AD. Group. Reinforcements were made according to the positions of stress concentration in the diagrams. The results of improvements of the front fork after reinforcement include¡G the deformation of normal rigidity was improved to 9.45mm from 12.89mm, and the lateral deformation was significantly improved to 0.97mm from 13mm. Other improvements of the frame structure after reinforcement contain the deformation: dual-side rigidity was improved to 6.6mm from 11.7mm, and the deformation of single-side rigidity was improved to 12.5mm. The rigidity of the head lug was 0.46mm and there is no need to reinforce it because it was meets requirements. Keywords: Numerical analysis, bicycle frame, prepreg, stress concentration.

The low-field magnetoresistance of colossal magnetic thin film can be enhanced by proton implantation. Compare with the as grown sample, the implantation samples has lower transition temperature and higher resistivity. By the hall measurement, we can get the carrier type and carrier concentration. The hall magnetoresistance (MRH) is much greater than the longitude magnetoresistance (MR). Chapter 1. Introduce experiment purpose and expected results. Chapter 2. Introduce the basic theorem of colossal magnetic materials. Chapter 3. The steps of experiment. Chapter 4. Results and discussion. Chapter 5. The conclusion.

Data of various marine environmental factors collected and integrated by the National Center of Ocean Research (NCOR) were used to search for possible statistics relationship with chlorophyll concentration of the Kuroshio and its adjacent waters off eastern Taiwan. The seaWiFS chlorophyll concentration in natural logarithm were used as dependent variable in General Linear Model¡]GLM¡^analysis, followed by least square means (lsmeans) and cluster analysis. Study area ranged from 21.5¡CN and 121¡CE to 26.5¡CN and 125¡CE eastern Taiwan. Data were first assembled, screened, transformed to natural logarithm and reorganized into monthly averages for individual geographical grid points of 10¡¦X 10¡¦. The result of GLM analysis shows that all factors have significant relationship with chlorophyll concentration, more than 20 regression formulae were found with different combination of variable. Results of standard regression analysis show their order of importance as: latitude, depth, longitude, light, sst, east and west current on upper 20 meter(c20EW), north and south current on upper 20 meter(c20NS) and eddy kinetic energy(EKE), respectively. Results of lsmeans listing by latitude and by longitude showed that area with higher chlorophyll concentration are on high-latitude and low-longitude area but not between and area near east Taiwan tend to have high concentration and decreased eastward. Results of cluster analysis indicated that chlorophyll concentration of western longitude, and northern as well as southern latitude are different from other area.