Rainfall derived inflow and infiltration (RDII) is a cause of sanitary sewer overflows and sewers exceeding capacity before the end of their design lives, but it is not well understood. Several methods exist to model RDII in existing sanitary sewers. These models are not applicable for design, which is frequently accomplished by applying constant unit rates. Two analytical probabilistic models are developed to estimate the contribution of RDII to peak flow and volume. The analytical models have been tested against computer simulations using long-term rainfall records and parameters calibrated using actual field data. One model relies on calibrated parameters from the RTK method; a commonly used method requiring a time-consuming calibration process. The second model relies on the R-value parameter of the RTK method, and a time of concentration parameter. By providing better information to designers, these analytical models aim to improve engineering decision-making in the design of sewer systems.

Rainfall derived inflow and infiltration (RDII) is a cause of sanitary sewer overflows and sewers exceeding capacity before the end of their design lives, but it is not well understood. Several methods exist to model RDII in existing sanitary sewers. These models are not applicable for design, which is frequently accomplished by applying constant unit rates. Two analytical probabilistic models are developed to estimate the contribution of RDII to peak flow and volume. The analytical models have been tested against computer simulations using long-term rainfall records and parameters calibrated using actual field data. One model relies on calibrated parameters from the RTK method; a commonly used method requiring a time-consuming calibration process. The second model relies on the R-value parameter of the RTK method, and a time of concentration parameter. By providing better information to designers, these analytical models aim to improve engineering decision-making in the design of sewer systems.

Infiltration facilities are source control mechanisms that are implemented in urban developments with reduced natural permeable surfaces. Despite the development of design criteria for infiltration facilities, these systems continue to fail due to headloss development, overflow, or chemical breakthrough. The limited research on the long-term performance of these systems has emphasized the role of physical filtration mechanisms within porous media filters to address concerns surrounding system failure, namely filter clogging. A continuous macroscopic depth filtration model was developed to investigate the clogging potential of the underlying sand filter. This continuous model furthers the understanding of temporal and spatial changes in system performance for the development of more appropriate design criteria and more suitable maintenance regimes. The characterization of long-term system performance by defining three different failure modes and a probabilistic approach comprises a comprehensive methodology by considering several performance criteria rather than assuming that one criterion dictates the overall system performance.

Los firmes permeables forman parte de la tendencia de construcción sosteniblecomo uno de los Sistemas Urbanos de Drenaje Sostenible (SUDS) más completos. Paraestudiar la capacidad de infiltración en laboratorio, se ha desarrollado el ensayo deresistencia a la colmatación con el Infiltrómetro Cántabro Fijo (ICF). Este ensayo es unaherramienta eficaz para la caracterización de diferentes tipos de pavimentos permeables,exponiéndolos a un aporte conocido de agua, variando el estado de colmatación y lainclinación de la superficie. Además, para estudiar la capacidad de infiltración encampo, se ha desarrollado el Infiltrómetro Cántabro Portátil (ICP), el cual permiteidentificar claramente cualquier tipo de superficie, permeable o impermeable, así comosu capacidad de infiltración. Respecto a la degradación de los materiales, se haanalizado la afección de los vertidos de hidrocarburos sobre mezclas bituminosasporosas fabricadas con distintos tipos de betunes. Por último, se han construido modelosde firmes permeables en el Laboratorio (FIDICA), en el Campus de Santander de laUniversidad de Cantabria y en el aparcamiento experimental de la Guía en Gijón. / Pervious pavements are part of the trend of sustainable construction as one of themost complete Sustainable Urban Drainage Systems (SUDS). The clogging resistancetest with the Fixed Cantabrian Infiltrometer (FCI) has been developed to study theinfiltration capacity in laboratory. The FCI is an effective tool for the characterization ofdifferent pervious pavements types, exposed to a known contribution of water, varyingclogging conditions and slope. Besides, the Portable Cantabrian Infiltrometer (PCI) hasbeen developed to study the infiltration capacity in field. The PCI allows clearlyidentifying any type of surface, pervious or impervious, as well as its clogging level.Regarding the materials degradation, the affection of hydrocarbons leakages overporous asphalt has been analysed. Lastly, models of pervious pavements have been builtin the FIDICA Laboratory and in the Santander Campus of the University of Cantabria,besides several experimental parking bays in La Guía, Gijón.

<p>Drylands, comprising arid and semi-arid areas and the dry subtropics, over some 40% of the world's land area and support approximately 2 billion people, including at least 1 billion who depend on dryland agriculture and grazing. 10-20% of drylands are estimated to have already undergone degradation or desertification, and lack of monitoring and assessment remains a key impediment to preventing further desertification. Change in vegetation cover, specifically in the spatial organization of vegetation may occur prior to irreversible land degradation, and can be used to assess desertification risk. Coherent spatial structures arise in the distribution of dryland vegetation where plant growth is localized in regular spatial patterns. Such "patterned vegetation" occurs across a variety of vegetation and soil types, extends over at least 18 million ha, occurs in 5 continents and is economically and environmentally valuable in its own right.</p> <p>Vegetation patterning in drylands arises due to positive feedbacks between hydrological forcing and plant growth so that the patterns change in response to trends in mean annual rainfall. Mathematical models indicate that vegetation patterns collapse to a desertified state after undergoing a characteristic set of transformations so that the condition of a pattern at any point in time can be explicitly linked to ecosystem health. This dissertation focuses on the mathematical description of vegetation patterns with a view to improving such predictions. It evaluates the validity of current mathematical descriptions of patterning for the specific case of small-scale vegetation patterns and proposes alternative hypotheses for their formation. It assesses the significance of seed dispersal in determining pattern form and dynamics for two cases: vegetation growing on flat ground with isotropic patterning, and vegetation growing on slopes and having anisotropic (i.e. directional) patterning. Thirdly, the feedbacks between local biomass density and infiltration capacity, one of the positive feedbacks believed to contribute to patterning, are quantified across a wide range of soil and climatic conditions, and new mathematical descriptions of the biomass-infiltration relationship are proposed. Finally the influence of land surface microtopography on the partitioning of rainfall into infiltration and runoff is assessed.</p> / Dissertation

In this thesis study, the use of clay-polymer nanocomposites for their applicability in landfill sites as a product of retardation of waste water infiltration was evaluated. For this purpose, organophilic clays from HDTMA+ organic cation and nanocomposites of montmorillonite were prepared. The bentonite samples B1, B2 and B3 dominantly contain 2:1 layer montmorillonite and 1:1 interstratification of illite/smectite mixed layer as clay minerals. B1 is an unmodified yellow bentonite and B2 is a grey bentonite modified from B1, by the addition of Na2CO3 (Soda Ash). They were obtained from Han&ccedil / ili (Kalecik-Ankara) bentonite deposit which belongs to the Hancili Formation of Early Pliocene age. B3 is a standard Wyoming (SWy-1) white bentonite and belongs to the Newcastle formation of Cretaceous age. Their cation exchange and swelling capacity values were determined and the values increase from B1, B2 to B3. In order to produce clay-polymer nanocomposites, firstly organoclays were produced in bentonite samples. Claypolymer nanocomposite production was achieved by in situ intercalative polymerization successfully with intercalation and partly exfoliation of clay minerals with polyacrylamide (PAM). The samples of sand (S1), sand+bentonite (S2) and sand+nanocomposite (S3) mixtures were prepared and their permeability was determined. As a result of these values, the permeability of samples decrease from S1, S2 to S3. The results imply that the permeability of sample decreases as the claypolymer nanocomposite content increases resulting in a retardation of water penetration throughout the sample. The product has a potential to be used as a retardant for waste water infiltration in landfill sites.

Alumina and zirconia based steel-MMCs were produced by pressureless Ti-activated melt infiltration using a high vacuum furnace. The effect of particle size and morphology on the formation of a ceramic network in-situ and MMC properties were investigated using three different alumina powders. The alumina/steel-MMCs were characterised for microstructure, Young’s modulus and strength at room temperature and elevated temperatures, and wear behaviour. Also the use of different types of steel was shown. Zirconia/steel-MMCs were produced using three different types of zirconia powder. With the use of monoclinic and partially stabilised (Ca-PSZ, Mg-PSZ) zirconia powder the effect of the monoclinic to tetragonal phase transformation on MMC microstructure and wear behaviour was shown. Further alumina preforms were successfully infiltrated in argon atmosphere at atmospheric pressure using a standard tube furnace. The infiltration in argon resulted in an increased degradation of the alumina particles. The infiltrations showed further investigations are needed for a better understanding of the mechanism of activated melt infiltration since different reactions (i.e. ceramic/metal interactions, dissolutions and evaporations) occur simultaneously during infiltration.

Zugl.: Karlsruhe, Univ., Diss., 2009

Residential and light-commercial buildings comprise a significant portion of buildings in the United States. They account for a large fraction of the total amount of energy used in the U.S., and they also represent environments where people spend the majority of their time. Thus, the design, construction, and operation of these buildings and their systems greatly affect energy consumption and exposures to airborne pollutants of both indoor and outdoor origin. However, there remains a need to improve knowledge of some key source and removal mechanisms of indoor and outdoor pollutants in residential and light-commercial buildings, as well as their connections to energy use and peak electricity demand. Several standardized field test methods exist for characterizing energy use and indoor air quality in actual buildings, although few explicitly address residential and light-commercial buildings and they are generally limited in scope. Therefore, the work in this dissertation focuses on improving methods to characterize three particular building components for their impacts on exposures to indoor pollutants and their implications for energy consumption: (1) central forced-air heating and cooling (HAC) systems, (2) HAC filters, and (3) building envelopes. Specifically, the research in this dissertation is grouped to fulfill two primary objectives of developing and applying novel methods to: (1) characterize and evaluate central air-conditioning systems and their filters as pollutant removal devices in residential and light-commercial buildings, and to explore their implications for energy consumption, and (2) characterize and evaluate the ability of two particular outdoor pollutants of concern (ozone and particulate matter) to infiltrate indoors through leaks in building envelopes. The research in this dissertation is divided into four primary investigations that fulfill these two objectives. The first investigation (Investigation 1a) addresses Objective 1 by first providing a detailed characterization of a variety of operational characteristics measured in a sample of 17 existing central HAC systems in occupied residential and light-commercial buildings in Austin, Texas, and exploring their implications for exposure to indoor pollutants, energy use, and peak electricity demand. Among the findings in this study, central air-conditioning systems in occupied residential and light-commercial buildings did not operate most of the time, even in the hot and humid climate of Austin, Texas (i.e., ~25% of the time on average in the summer). However, average recirculation rates still make central air-conditioning systems competitive as particle removal mechanisms, given sufficient filtration efficiency. Additionally, this investigation used a larger, much broader, dataset of energy audits performed on nearly 5000 single-family homes in Austin to explore common inefficiencies in the building stock. Residential and light-commercial air-conditioning systems are often inefficient; in fact, residential central air-conditioning systems in particular likely account for nearly 20% of peak electric demand in the City of Austin. As much as 8% of peak demand could be saved by upgrading all single-family homes in Austin to higher-efficiency equipment. The second investigation (Investigation 1b) also addresses Objective 1 by developing and applying a novel test method for measuring the in-situ particle removal efficiency of HAC systems and filters in residential and light-commercial buildings. Results from the novel test method as performed with three test filters and 0.3–10 μm particles in an unoccupied test house agreed reasonably well with results from other field and laboratory test methods. Low-efficiency filters did not increase particle removal much more than simply running the HAC system without a filter, and higher-efficiency filters provided greater than ~50% removal efficiency for most particles greater than 1–2 μm in diameter. The benefit of this test method is that it can be used to measure how filters perform in actual environments, how filter removal efficiency changes with actual dust loading, and how much common HAC design and installation issues, such as low airflow rates, duct leakage, fouled coils, and filter bypass airflow, impact particle removal in real environments. The third investigation (Investigation 2a) addresses Objective 2 by developing and applying a novel test methodology for measuring the penetration of outdoor ozone, a reactive gas, through leaks in exterior building envelopes using a sample of 8 single-family residences in Austin, Texas. These measurements represent the first ever measurements of ozone penetration factors through building envelopes of which I am aware, and penetration factors were lower than the usual assumption of unity (i.e., P = 1) in seven of the eight test homes (ranging from 0.62±0.09 to 1.02±0.15), meaning that some building envelopes provide occupants with more protection from indoor exposures to ozone and ozone reaction byproducts than others. Additionally, ozone penetration factors were correlated with some building characteristics, including the amount of painted wood siding on the exterior envelope and the year of construction, suggesting that simple building details may be used to predict ozone infiltration into homes. Finally, the fourth investigation (Investigation 2b) also addresses Objective 2 by refining and applying a test methodology for measuring the penetration of ambient particulate matter through leaks in building envelopes, and using a sample of 19 single-family residences in Austin, Texas to explore correlations between experimentally-determined particle penetration factors and standardized fan pressurization air leakage tests. Penetration factors of particles 20–1000 nm in diameter ranged from 0.17±0.03 to 0.72±0.08 across 19 homes that relied solely on infiltration for ventilation air. Particle penetration factors were also significantly correlated with results from standardized fan pressurization (i.e., blower door) air leakage tests and the year of construction, suggesting that occupants of older and leakier homes are exposed to more particulate matter of outdoor origin than those in newer tighter homes. Additionally, blower door tests may actually offer some predictive ability of particle penetration factors in single-family homes, which could allow for vast improvements in making easier population exposure estimates. Overall, the work in this dissertation provides new methods and data for assessing the impacts of central air-conditioning systems, filters, and building envelopes on human exposure to indoor pollutants and energy use in residential and light-commercial buildings. Results from these four primary investigations will allow building scientists, modelers, system designers, policymakers, and health scientists to make better informed decisions and assumptions about source and removal mechanisms of indoor pollutants and their impacts on building energy consumption and peak electricity demand. / text

Selective laser sintering (SLS) is a commercial, powder-based manufacturing process that produces parts with complicated shape and geometry based on a computer solid model. One of the major drawbacks of SLSed inter-metallic and ceramic parts is their high porosity because of the use of binder system. High porosity results in poor mechanical, electrical and thermal properties of the preform and hence renders it unsuitable for various applications. This thesis attempts to infiltrate SLSed preforms by carrying out electrochemical deposition of metal ions inside the interconnected pore network. One of the major benefits of carrying out this novel process is low processing temperature as opposed to existing methods such as melt infiltration. Low temperature reduces both energy consumption and associated carbon-footprint and also minimizes undesirable structural changes. Both conductive and non-conductive preforms may be electrochemically infiltrated, and MMCs produced by this method have potential for use in structural applications. / text