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Pollution in developing countries is generally much worse than in developed countries, and is caused by the widespread use of poor quality machines both industrial and in motor vehicles. Obviously, motorised vehicles are a major source of today's pollution. Motor vehicle emissions, whether gases, particulate matter or noise, can all be dangerous. Particulate matter, especially very fine particulates, is the major concern of this thesis, which considers their capacity for penetrating deep into the lungs and developing slowly to cause noticeable illnesses. Low-income people who live within the city centre are the most exposed to traffic pollution whether on the move or indoors. Low cost housing, whether self built or provided by government or private sectors, often exposes occupants to both lack of thermal comfort and pollutant intrusion from adjacent street traffic. Houses in warm-humid regions depend on large openings and through ventilation for thermal comfort. Openings allow air pollution and noise to penetrate these houses easily, thereby affecting the health, comfort and well-being of residents. Closing all openings and changing from natural ventilation to air conditioning is not however a practical solution for low cost housing. This study explores the effect of boundary fences, vegetation, and detailed opening design in reducing the penetration of airborne particulates and noise into the living spaces of typical low-cost urban houses. The experiments carried out for this study include computational simulation, manual calculation and field experiments. The research indicated that there are feasible and practical solutions to the reduction of fine particulate matter and street noise in such housing by using solid and massive barriers combined with vegetation and a specific window type. Solid and massive barriers were constructed to slow the progress of the pollutants by reduction of wind speeds on approaching obstructions. If the wind slows down enough, this effectively 'holds' the pollutant in place. In this case, the deposition surface was provided by vegetation with dense foliage. The surface of the vegetation was predicted to deposit particulate matter effectively, which would then be washed away naturally by rains. Some types of leaves were studied to find the relationship between the physical characteristics of leaf surfaces and their ability to deposit particulate matter. Before entering the living spaces, the particulate matter then encounters further obstruction by jalousie windows thus reducing its concentration. The solid and massive fence also created an acoustic shadow and noise was then further reduced by the jalousie windows. The resulting indoor noise level was found to be closer to the proposed Indonesian standards of 45 dBA.

This paper considers a free energy functional and corresponding free boundary problem for multilayered structures which arise from a mixture of a block copolymer and a weak solvent. The free boundary problem is formally derived from the limit of large solvent/polymer segregation and intermediate segregation between monomer species. A change of variables based on Legendre transforms of the effective bulk energy is used to explicitly construct a family of equilibrium solutions. The second variation of the effective free energy of these solutions is shown to be positive. This result is used to show more generally that equilibria are local minimizers of the free energy.

The MIUU meso-scale model has been used to evaluate a new lateral boundary condition. The new lateral boundary condition is a combination of two lateral boundary conditions used in regional models, the flow relaxation scheme and the tendency modification scheme. The impact of different lateral boundary formulations on meso-scale phenomena, such as convective boundary layers, nocturnal jets, sea breezes and mountain waves (Bora winds) has been studied. When, for instance, stably stratified air with a constant wind speed is advected through the lateral boundaries into a meso-scale model with a flat and homogenous land surface, the convective boundary layer is reduced in height and the nocturnal jet is reduced in magnitude up to a distance of 750 km from the inflow lateral boundary. This is the case, when the most common lateral boundary condition is used, namely the flow relaxation scheme, where the flow relaxation parameter is constant with height and a function of the horizontal grid points only. In the other tests a flow relaxation parameter is used that is very small up to a certain level above ground, increasing with height to a maximum value higher up, and being constant above this upper level. Then, the convective boundary layer and the nocturnal jet are fully developed already at 23 km from the inflow lateral boundary. When, for instance, islands are not represented in the large-scale model, due to the coarse grid resolution, but well represented in the meso-scale model, stably stratified air can be advected into the meso-scale model even during daytime. Then, artificial thermal circulations can arise at the lateral boundaries of the meso-scale model, and collide with a real sea-breeze circulation that develops at the coast-line. These artificial thermal circulations disappear only when the flow relaxation parameter is very small in the lowest levels. When mountain waves (Bora winds) are simulated in a relatively small model domain, the critical layer, i.e. the layer where the nonlinear large-amplitude mountain wave is generated and broken, is surprisingly displaced irrespective of the tested lateral boundary formulations. In many simulations large-scale fields have to be introduced into meso-scale models. If only the flow relaxation scheme is used, the flow relaxation parameter has to be “constant-in-height” and relatively large in order to introduce large-scale temperature and wind changes with the right time-scale at all levels. However, with the new lateral boundary condition, the flow relaxation parameter can be kept very small in the lowest kilometers above ground. A small value of the flow relaxation parameter means that the convective boundary layer and the nocturnal jet at the lateral boundaries are not affected by the boundary conditions, and furthermore, no artificial thermal circulations are created. At the same time, large-scale temperature and wind changes are correctly introduced at all heights during the prescribed time into the meso-scale model through the tendency modification scheme. / Den mesoskaliga MIUU modellen har använts för test av olika laterala gränsvillkor. Ett nytt lateralt gränsvillkor har konstruerats. Detta nya gränsvillkor är en kombination av två gränsvillkor, nämligen ’the flow relaxation scheme’ och ’the tendency modification scheme’. Inverkan av olika gänsvillkorsformuleringar på mesoskaliga fenomen som konvektiva gränsskikt, ’nocturnal’ jets, sjöbrisar och bergsvågor (Boravindar) har studerats. När stabilt skiktad luft med konstant vindhastighet advekteras in genom de laterala ränderna in till en mesoskalig modelldomän, som har en slät och homogen landyta, kommer det konvektiva gränsskiktets höjd och styrkan på ’nocturnal’ jeten att påverkas av gränsvillkoret. Randvillkoret kan påverka temperatur och hastighetsfältet upp till 750 km:s avstånd från inflödesranden. Detta sker när det vanligaste laterala gränsvillkoret används, nämligen, ’the flow relaxation scheme’. I detta schema är ’flow relaxation’-parametern konstant med höjden, dvs endast en funktion av de horisontella gridpunkterna. Sensivitetsstudier på värdet och formen av ’flow relaxation’-parametern har utförts. En ’flow relaxation’-parameter, som är mycket liten upp till en viss nivå och sedan ökar med höjden påverkar temperatur- och hastighetsfältet mycket mindre. Randvillkorets påverkan är då minimal redan på 23 km:s avstånd från inflödesranden och det konvektiva gränsskiktet och ’nocturnal’ jeten kan bli fullt utvecklade. Om till exempel öar, som är väl representerade i den mesoskaliga modellen, inte är representerade i den storskaliga modellen pga dess grova upplösning, kan stabilt skiktad luft advekteras in till den mesoskaliga modelldomänen till och med under dagtid. Det kan då uppstå en artificiell termisk cirkulation vid de laterala ränderna hos den mesoskaliga modellen. Denna artificiella termiska cirkulation kan sedan kollidera med en verklig sjöbriscirkulation. Detta kan förstöra den mesoskaliga modellösningen totalt. Denna artificiella termiska cirkulation försvinner endast då ’flow relaxation’-parametern är väldigt liten i de lägsta nivåerna. När bergsvågor (Boravindar) simuleras i en relativt liten modelldomän så är det kritiska skiktet, dvs det skikt där de icke-linjära vågorna med stor amplitud bryts och genereras, förflyttat jämfört med referensfallet där de laterala ränderna var långt borta från det studerade området. Detta sker förvånansvärt oberoenda av vilken lateral gränsvillkorsformulering som används. I många simuleringar ska storskaliga processer såsom fronter och geostrofiska vindänd-ringar införas till den mesoskaliga modellen. Om endast ’the flow relaxation scheme’ används måste ’flow relaxation’-parametern vara konstant med höjden och relativt stor. Detta för att storskaliga temperatur- och vindändringar skall kunna introduceras till den mesoskaliga modellen med rätt tidskonstant och på alla höjder. I det nya laterala gränsvillkoret behöver ’flow relaxation’-parametern inte vara lika stor och inte heller konstant med höjden. Temperatur- och vindändringar är ändå korrekt introducerade med exakt tidsskala i alla nivåer in till den mesoskaliga modellen. Detta sker genom användandet av det s.k. ’tendency modification’-schemat. Dessutom kan det konvektiva gränsskikt, ’nocturnal’ jeten och sjöbrisar utveklas korrekt i närheten av de laterala ränderna.

Approved for public release; distribution is unlimited. / The effects of shoaling inner shelf solitons on the bottom boundary layer have been observed and analyzed over a two month summer period at the Monterey Inner Shelf Observatory in Monterey, CA, during 2002. Utilizing CTD data to characterize the temperature field of the water column, Acoustic Doppler Current Profiler (ADCP) data to measure the velocity structure from 3m height above the bed (HAB) to the near surface, and Bistatic Doppler Velocity Sediment Profiler (BDVSP) data to measure the velocity structure and sediment concentration from a range of 60cm to 1cm HAB, solitary internal waves and internal tidal bores were regularly observed at the observation site. These events were characterized by their large isotherm displacements and the sudden change from near surface to near bed stratification as the internal tidal bores passed the observation site. Cross-shore timeseries revealed that the strongest events pushed water onshore near the surface and offshore near the bed, indicating a baroclinic water column during their passage. To analyze their effects on the bottom boundary layer, 3m HAB ADCP and BCDV velocities were compared with backscatter data and surface gravity wave energy at 3m HAB to determine their relative contribution to bed stress and resulting sediment suspension. As the strong internal waves passed, a logarithmic layer formed indicating that shear stress above the bed was occurring. This allowed the friction velocity within the log layer to be estimated. Combining this term with the stress contribution due to the wave energy, the total stress on the bed was then estimated. From this it was determined that typically moderate surface gravity wave forcing at the bed suspended sediment, while solitary internal waves and internal tidal bores continued to transport suspended sediment offshore near the bed. / Ensign, United States Navy

The uncertainty in the determination of the momentum and scalar fluxes remains one of the main obstacles to accurate numerical forecasts in low to moderate wind conditions. For example, latent heat fluxes computed from data using direct covariance and bulk aerodynamic methods show that there is good agreement in unstable conditions when the latent heat flux values are generally positive. However, the agreement is relatively poor in stable conditions, particularly when the moisture flux is directed downward. If the direct covariance measurements are indeed accurate, then they clearly indicate that the bulk aerodynamic formula overestimate the downward moisture flux in stable conditions. As a result, comparisons of the Dalton number for unstable and stable conditions indicate a marked difference in value between the two stability regimes. Investigations done for this thesis used data taken primarily at the Air-Sea Interaction Tower (ASIT) during the Coupled Boundary Layers and Air-Sea Transfer (CBLAST) Experiment 2003 from the 20-27 August 2003. Other data from the shore based Martha's Vineyard Coastal Observatory (MVCO) and moored buoys in the vicinity of the ASIT were also incorporated. During this eight day period, the boundary layer was often characterized by light winds, a stably stratified surface layer and a swell dominated wave field. Additionally, the advection of warm moist air over cooler water resulted in fog formation and a downward flux of moisture on at least three occasions. Therefore, a primary objective of this thesis is to present a case study to investigate the cause of this shortcoming in the bulk formula under these conditions by examining the physical processes that are unique to these boundary layers. Particular attention will be paid to the behavior of the Dalton number in a stable marine atmospheric boundary layer under foggy conditions using insights derived from the study of fog formation and current flux parameterization methods.

Leonardi & Barley menar att organisationsstudier bör fokuseras mot hur personer arbetar med datorer och datasystem, samtidigt som Orlikowski menar att studier av arbete med datasystem bör baseras på praktikteorier. Studien kombinerar därför två teorier för att studera modernt arbete som till stor del baseras på datorsystem eller användandet av datorer, CHAT och boundary objects. Studiens syfte är att analysera om praktikteorin, CHAT kan användas för att studera ett modernt arbete som är teknikbaserat, gränsöverskridande och kunskapsintensivt, nämligen internprissättning. Slutsatserna är att CHAT går att använda för modernt arbete trots att teorins materiella bakgrund inte tagit informationsteknik i beaktande. Samtidigt belyste användningen av teorin att de geografiska gränserna mellan aktivitetssystem blir mindre, subjekten kan befinna sig på olika breddgrader utan problem, samtidigt som de olika elementen får fler funktionsområden.

This thesis aims to contribute to the understanding of transitional flows in the blade boundary layers of axial compressors. Two experiments are described, the first examining in detail the transitional boundary layer on a simulated controlled-diffusion blade and the second surveying the mid-height flowfield in an embedded stage of a low-speed axial compressor. The velocity distribution on the simulated blade is identical to the Velocity distribution on the suction surface of the blades in the axial compressor. At 2 Reynolds numbers and 3 levels of freestream turbulence, a single hot wire was used to conduct a boundary layer survey on a simulated controlled-diffusion blade. Integral parameters of the boundary layers are explored to dene the length and nature of transition. At low Reynolds number there is a separated or near separated region at the leading edge which does not lead to turbulence. Transition covers a length of approximately 20% of the blade chord, starting between 20% and 30% chord. The position of transition is strongly influenced by the level of freestream turbulence. Most of the transition process occurs within the decelerating flow region which exists from 20% of the chord. At high Reynolds number, a leading edge separation bubble leads to transition within 2% of the blade chord. Abu-Ghannam & Shaws correlation for the start and length of transition was found to predict the start of transition well for attached flows, but could not be relied upon for separated flows. It is apparent that the correlation was not designed for the very strong Velocity gradients in the leading edge region, and probably not for separated flow. _ Three flow conditions in the axial compressor were used: design speed, peak efficiency, low Reynolds number at peak efficiency (the machine was slowed to one-quarter speed) and design speed near the stall. Using hot wires at mid-height, axial and circumferential velocity and turbulence information was obtained. Wakes and structure within wakes are visible in the turbulence and Reynolds stress distributions. The wakes of more than one upstream blade row are visible; the region where two wakes intersect gives some information about interaction between a stator blade Wake and a rotor blade boundary layer. Some information is available about the length scale 'distribution inside and outside wakes. Secondary flow in the axial-circumferential plane shows motion within wakes and a vortex in the near-stall flowfield, shed preferentially at one point in the blade-passing cycle.

Student Number : 9804032J - PhD thesis - School of Mathematics - Faculty of Science / The focus of this thesis is the spectral structure of second order self-adjoint differential operators on graphs. Various function spaces on graphs are defined and we define, in terms of both differential systems and the afore noted function spaces, boundary value problems on graphs. A boundary value problem on a graph is shown to be spectrally equivalent to a system with separated boundary conditions. An example is provided to illustrate the fact that, for Sturm-Liouville operators on graphs, self-adjointness does not necessarily imply regularity. We also show that since the differential operators considered are self-adjoint the algebraic and geometric eigenvalue multiplicities are equal. Asymptotic bounds for the eigenvalues are found using matrix Pr¨ufer angle methods. Techniques common in the area of elliptic partial differential equations are used to give a variational formulation for boundary value problems on graphs. This enables us to formulate an analogue of Dirichlet-Neumann bracketing for boundary value problems on graphs as well as to establish a min-max principle. This eigenvalue bracketing gives rise to eigenvalue asymptotics and consequently eigenfunction asymptotics. Asymptotic approximations to the Green’s functions of Sturm-Liouville boundary value problems on graphs are obtained. These approximations are used to study the regularized trace of the differential operators associated with these boundary value problems. Inverse spectral problems for Sturm-Liouville boundary value problems on graphs resembling those considered in Halberg and Kramer, A generalization of the trace concept, Duke Math. J. 27 (1960), 607-617, for Sturm-Liouville problems, and Pielichowski, An inverse spectral problem for linear elliptic differential operators, Universitatis Iagellonicae Acta Mathematica XXVII (1988), 239-246, for elliptic boundary value problems, are solved. Boundary estimates for solutions of non-homogeneous boundary value problems on graphs are given. In particular, bounds for the norms of the boundary values of solutions to the non-homogeneous boundary value problem in terms of the norm of the non-homogeneity are obtained and the eigenparameter dependence of these bounds is studied. Inverse nodal problems on graphs are then considered. Eigenfunction and eigenvalue asymptotic approximations are used to provide an asymptotic expression for the spacing of nodal points on each edge of the graph from which the uniqueness of the potential, for given nodal data, is deduced. An explicit formula for the potential in terms of the nodal points and eigenvalues is given.

Student Number : 9902718G - MSc dissertation - School of Geosciences - Faculty of Science / The Late Permian (251.0 ± 0.4 Ma) mass extinction is universally acknowledged as the most consequential of the five major Phanerozoic mass extinctions. More than 90% of marine species, ~70% of terrestrial vertebrates, and ~90% of plant life were lost in a very short interval. The nature of the Permian-Triassic (P-Tr) boundary and the cause of the mass extinction associated with it have been the subject of extensive international debate. Possible causes for the P-Tr extinction include asteroid/comet impact, oceanic anoxia, volcanism, methane clathrate dissociation, or combinations of these causes. Geochemical studies of the P-Tr boundary have traditionally been focused on the marine realm, as the boundary in continental sections is typically difficult to pinpoint. One continental setting of the P-Tr boundary that has, however, received much attention is that in the main Karoo Basin, South Africa. The Karoo Basin is a large retro-arc foreland basin which accumulated sediment from the Carboniferous (300 Ma) through to the Early Jurassic (180 Ma) in southwestern Gondwana. Mineralogical and geochemical investigations across two palaeontologically well-constrained continental P-Tr boundary sections at Commando Drift Dam and Wapadsberg in the southern Karoo Basin of South Africa have been undertaken in order to aid in our understanding of this extinction event. The Commando Drift Dam section is also constrained palaeomagnetically. There is a change in paleosol colour across the P-Tr boundary from green-grey to red-brown, which is believed to reflect a change of oxidizing conditions at the P-Tr boundary. Quartz grains were examined for possibly impact-produced microdeformation features, but these were not found. Iridium concentrations are below the detection limit (by instrumental neutron activation analysis) and the sections could not be evaluated as to whether any significant enrichment has taken place at the P-Tr boundary. Major element chemical profiles are dominated by the signatures of carbonate nodular horizons in both sequences. Iron contents (and accompanying siderophile element abundances) increase across the palaeontologically-defined P-Tr boundary, followed by a decrease thereafter. The major element concentrations, together with the effects of weathering, largely control trace element distribution. Carbon isotopic results from the Commando Drift Dam section show a gradual decrease in values before the P-Tr boundary, with a larger negative excursion at the P-Tr boundary. Above the boundary, gradual recovery to initial ratios is observed, followed by another gradual decrease in values to the palaeomagnetically defined boundary. No evidence supporting an extraterrestrial impact extinction mechanism has been found. Rather, the carbon isotope data from this study support two gradual palaeoclimatic changes separated by a sudden change in the carbon isotopic content of the atmosphere. The size and nature of these excursions support the addition of large amounts of anoxic material into the atmosphere. This is proposed to have been caused by the multiple influx of carbon dioxide, methane and other greenhouse gases at various times and by different mechanisms. Such a release of carbon dioxide, methane and other greenhouse gases could have been caused by the coincident volcanic event (the formation of the Siberian Traps) and the episodic release of methane clathrates.