Atmospheric aerosol is a ubiquitous component of the Earth atmosphere. By mass, aerosol natural sources override anthropogenic ones, the latter constituting less than 5% to the total aerosol loading (Jaenicke, 2008). Nevertheless, in urban environment the contribution can increase to 80-90%. Since anthropogenic sources are mostly associated with high temperature processes, urban aerosol number size distribution is usually dominated by ultrafine particles - UFPs (d<100 nm). The UFPs have the highest surface/mass ratios among aerosol particles and bond the highest pollutant loading as per particle mass. Additionally, the UFPs exhibit the highest deposition efficiency in deep region of the human respiratory tract. Therefore, this study focuses to urban aerosol particle spatial-temporal, physical and chemical characterization and source apportionment with special emphasis to the UFPs. The first study in residential district of Ostrava-Radvanice and Bartovice, an air pollution hot spot in Europe, identified industry being dominant sources of UFPs. High particle number concentrations (NC) were measured at the hot spot, with peaks up to 1.4x105 particles cm-3 during plume events, i.e. downwind an industrial facility. The plume-originating UFPs were mostly composed of 19−44 nm nanoparticles heavily...

A systematic NMR cryo-porometry and -diffusometry study using nitrobenzene as a probe liquid is carried out in order to characterise pore structures of hierarchically-organised porous silica monolith possessing mesopores along with a 3D bicontinuous macropore network. The result obtained from NMR cryoporometry shows the presence of a relatively wide mesopore size distribution of 10-35 nm. Furthermore, NMR cryodiffusometry indicates that whilst the mesopores are highly tortuous (Tmeso ≈6), they have little influence on the overall tortuosity of the material (Tmacro ≈1.5), which is largely dominated by the macropores (Toverall ≈1.7).

This project deals with the mixed micellar and interfacial properties of mixtures of three surfactants [sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and tetraethylene glycol monododecyl ether (C12E4)] with ABA symmetrical triblock copolymer (Pluronic F127), which has many industrial applications. Evidence of F127 micellisation and interaction with surfactants in the aqueous phase is inferred through interfacial tension measurements. The solution containing diluted monomeric F127 showed complex formation with surfactants before the latter self-aggregate as pure micelles. The simultaneous presence of ionic surfactants and micellar F127 in solutions displayed a decrease of interfacial activity and led to the conclusion of F127 micelles disruption. C12E4 was found to interact differently with micellar F127 in forming mixed micelles, and no loss of interfacial activity was recorded. This “association-dissociation” behaviour of F127 and surfactants was leveraged to understand the stability of mineral oil in water emulsions formulated with them in the presence of sodium phosphate (Na3PO4). The mechanisms of emulsions breakdown were found to rely on aggregation behaviour and complex structure of F127 and surfactants mixtures in solution. Laser diffraction showed that unlike SDS and CTAB, mixed-emulsifier systems containing C12E4 are stable to both flocculation, Ostwald ripening and coalescence. Due to electrostatic repulsion between its head group and F127 hydrophilic block, and also because of the combined effect of Ostwald ripening and coalescence, CTAB emulsifier containing systems displayed quicker instability than SDS. SDS containing systems showed a progressive shifting of droplets size distributions to bimodality as SDS concentration was increased and heat exposure pursued, revealing the activity of two distinct population of droplets in the emulsions. More insight on the mechanisms underlying the stability of the three mixed emulsifier systems was gained in performing optical microscopy and rheology measurements; the results were found to be consistent with particle size distribution. / Dissertation (MSc (Applied Science: Chemical Technology))--University of Pretoria, 2020. / Chemical Engineering / MSc (Applied Science: Chemical Technology) / Unrestricted

Ecosystems provide important functioning and services, like biomass for bioenergy production or storage of atmospheric carbon. Two examples of such ecosystems are temperate grasslands and tropical forests. Both vegetation are rich of various species, whereby each of the respective ecosystem benefits from its species-richness concerning their functioning, i.e. productivity. In this thesis both vegetation are in the focus of the investigations. In the first chapter, a review of existing grassland and vegetation models provides an overview of important aspects, which have to be considered for modelling temperate grasslands in the context of biomass production. Based on the review, new conceptual modelling approaches for temperate grasslands are proposed. In the third chapter, derived from the suggested concept, the process-oriented and individual-based grassland model Grassmind is presented. In the fourth chapter, the model Grassmind is used in order to parameterize and simulate the annual dynamics of a typical Central European grass species. Grassmind is able to reproduce the structure and dynamics of a temperate grass species. With reference to the parameterized grass species, a simulation study using defined species groups is performed in order to investigate on the effect of the richness of species groups on aboveground productivity. We do not observe a significant positive effect of species group richness on productivity, which is explained by limitations of using the parameterized grass species as a reference. In the fifth chapter, comprehensive investigations are carried out on the example of stem size distributions in forests concerning their statistical analyses, i.e. by using maximum likelihood estimation. The effects of uncertainties, i.e. binning of measured stem sizes or random measurement errors, are examined in detail. Uncertainties bias the analyses of maximum likelihood estimations. It is shown, that the use of modified likelihood functions, which include either binning or measurement errors, reduce these biases to a large extent. For both studies, i.e. modelling of temperate grasslands and analysing stem size distributions of forests, the presented investigations are discussed and possible examinations are suggested for future research in the last chapter.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21096号 / 工博第4460号 / 新制||工||1693(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 田中 宏明, 准教授 大下 和徹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24429号 / 理博第4928号 / 新制||理||1704(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 三宅 亮, 教授 野口 高明, 教授 下林 典正 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

<div>Rain drop size distributions (DSDs) in severe convective storms are highly variable in time and space. DSDs can be derived from polarimetric radar observations at high spatiotemporal resolution but these observations are often lacking near the surface owing to radar horizon issues. Disdrometers provide “ground-truth” measurements and validation of radar-derived DSDs but are by nature limited point measurements. Moreover, substantial evolution of the DSD can occur between the lowest radar elevation angle and the surface. Recent studies have shown that hydrometeor size sorting (HSS) is an important and even dominant process contributing to DSD evolution in severe storms; many physical processes such as the strength of the updraft, transient effects, and storm-relative mean winds are contributing factors to continued size sorting. In this study, we focus on strong storm-relative mean winds that induce sustained size sorting owing to the different residence times of hydrometeors of different sizes as they fall in severe storms. The resulting differential advection leads to a distinct horizontal spread of hydrometeors of different sizes at the bottom of a given layer. The goal of this study is to evaluate the impact of size sorting on DSD evolution from the radar level to the surface. To accomplish this, we develop and apply a raindrop trajectory model to compute the evolution of DSDs between radar observations aloft and the surface. For simplicity and to isolate the effects of size sorting, we neglect processes such as breakup, collection, and evaporation, and assume a horizontally homogeneous wind profile. We use disdrometer and radar data, which measure DSDs at the surface and provide the observed quantities aloft, respectively. The disdrometer data was collected from portable disdrometers as a collaboration between Purdue University, University of Oklahoma, University of Massachusetts, and the National Severe Storms Laboratory during the VORTEX-SE 2017 field campaign. NEXRAD data from KHTX Huntsville, AL and KGWX Columbus Air Force Base, MS was retrieved from the National Centers for Environmental Information (NCEI).</div><div><br></div><div>We evaluate three separate cases, a tornadic QLCS on 30 April 2017, a cluster storm on 27 March 2017, and a squall line on 25 March 2017. After the radar data is pre-processed, we retrieve the DSDs from the radar by assuming a gamma distribution and discretize them into PARSIVEL bins to produce a gridded dataset of DSDs. We then apply the raindrop trajectory model to compute the DSDs at the surface which are then compared directly with disdrometer observations. Analysis and comparisons from all cases yield similar results in that-the sorted radar DSDs at the surface are overall closer to the disdrometer observations than the original radar DSDs aloft. Results also show that the spatial variation of DSDs is higher at the surface due to size sorting by the storm-relative mean winds.</div><div><br></div>

Due to the endangerment of the June sucker (Chasmistes liorus), the lower two miles of Hobble Creek, Utah has been the focus of several restoration efforts. The portion of the creek between Interstate 15 and Utah Lake has been moved into a more "natural" channel and efforts are now being made to expand restoration to the east side of the freeway. This thesis reports on three different parts of a sedimentological analysis performed on Hobble Creek. The first part is a data set that contains information about the particle size distribution on the bed of Hobble Creek between 400 W and Interstate 15 in Springville, Utah. Particle size distributions were obtained for eleven sub-reaches within the study section. Particle size parameters such as D50 were observed to decrease from an average of 72 mm to 24 mm downstream from the 1650 W crossing and Packard Dam. Streambed armoring was observed along most of the reach. This data set can be used as input for PHABSIM software to determine the location and availability of existing spawning material for June sucker during a range of flows. The second part of this thesis compares predictions from four bed-load transport models to bed-load transport data measured on Hobble Creek. In general, the Meyer-Peter, Muller and Bathurst models overpredicted sediment transport by several orders of magnitude while the Rosgen and Wilcock methods (both calibrated models) were fairly accurate. Design channel dimensions resulting from the bed-load transport predictions diverged as a function of discharge. Once validated, the models developed in this section can be used by design engineers to better understand sediment transport on Hobble Creek. The models may also be applied to other Utah Lake tributaries. The third section of the thesis introduces a detailed survey data set that covers the Hobble Creek floodplain on the shifted section between Interstate 15 and Utah Lake with an approximate 10 foot resolution grid. Water surface elevations at two flows, along with invert, fence, saddles, and other points, are labeled in the survey. A comparison with a survey completed last year did not reveal any significant lateral changes caused by the 2010 spring runoff. Due to the potential importance of the side ponds to June sucker survival, this data set can be used to monitor sedimentation in the side ponds. It may also be used in a GSSHA model to determine the magnitude of flow that is required before each side pond will be connected to the main channel.

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.

Yes / The effect of screw configuration on granule size distribution (GSD) using gPROMS FormulatedProduct (gFP) software to perform optimization, estimation of complex processes, and analyses is evaluated. Twin-screw granulation modeling was used to investigate the contribution of screw configuration and liquid-to-solid (L/S) ratio on GSD. Lactose and Avicel were the granulating materials. Twelve different configurations were investigated under three feed rates as consistent with literature and at various L/S ratios. Results indicate that kneading elements promote the recovery of 100–1000 µm granules while reducing the production of oversized granules. Higher feed rates support the production of fines and agglomerates, while a low feed rate produces 100–1000 µm granules. / Ghana Scholarship Secretariat