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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.

Effect of subcrust-aeration regime on the kinetics and mechanisms of clogging and unclogging of septic effluent-perfused soils

Perry, James Jennings. January 1983 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 149-162).

Application of Sequential Microwave/Aeration Process for the Removal of Ammonia from Landfill Leachate

Dong, Sainan January 2015 (has links)
Application of microwave (MW) radiation followed by aeration (A) for the purpose of ammonia removal from both synthetic solutions and landfill leachate was investigated in this study. Four sets of experiments: water bath (WB), microwave (MW), sequential microwave/aeration process (MW+A), and sequential water bath/aeration process (WB+A) were conducted using synthetic solution. MW and MW+A tests were applied on the landfill leachate as well. For each test, either 100 mL of synthetic solution or landfill leachate was used. All the tests were conducted with three replicates in batch scale. For both economic and safety concerns, the samples’ temperature were maintained below the boiling point. One-way ANOVA tests and T-tests were conducted to analyze the differences of ammonia removal efficiencies among different methods. Both thermal and non-thermal effects for the sequential microwave/aeration process were investigated. Factorial design and response surface methodology (RSM) were applied to evaluate and optimize the effects of pH, MW energy level and microwave power output. Results confirmed that the sequential microwave/aeration process was an effective approach for removal of ammonia from aqueous systems. Maximum ammonia removal of 81.7 % for synthetic solution and 70% for landfill leachate was achieved by applying 7.8 KJ MW energy output/L sample and 10 minutes aeration. When apply the sequential microwave/aeration process to synthetic solution, at optimum condition of pH 10.5, 7.8 KJ MW energy output/L sample and 10 minutes aeration time, the contribution of thermal process was 39%, while 61% for non-thermal processes (33% for aeration and 28% for EMF). Statistical analysis of synthetic solution tests data using RSM showed that ammonia removal efficiency strongly depended on pH and MW energy output. R square of 0.941 indicates that observed results fitted well with the model prediction. Optimum pH and MW energy output level for ammonia removal was 11 and 7.8 KJ MW energy output/L sample respectively, and under this condition, maximum ammonia removal efficiency predicted for synthetic solution was 76.3%.

Diffuser Operations at Spring Hollow Reservoir

Gantzer, Paul Anthony 28 May 2002 (has links)
Stratification is a natural occurrence in deep lakes and reservoirs. This phenomenon results in two distinct layers, the warmer, less dense epilimnion on top and the colder, denser, hypolimnion on the bottom. The epilimnion remains saturated with dissolved oxygen (DO) from mass transfer with the atmosphere, while the hypolimnion continues to undergo oxygen-depleting processes. During seasons of high oxygen demand the hypolimnion often becomes anoxic and results in the release of compounds, such as Iron, Manganese, Hydrogen Sulfide, and Phosphorous from the sediment. Iron, Manganese, and Hydrogen Sulfide can require addition Chlorine for water treatment plants, thus increasing cost and the potential production of DBP's, while the release of phosphorous results in algal blooms the following year. Spring Hollow Reservoir, located in Roanoke County, Virginia is a deep reservoir that undergoes stratification during the summer months. During 1997 Roanoke County purchased a bubble-plume diffuser from Tennessee Valley Authority (TVA) to oxygenate the hypolimnion to maintain long-term water quality. Spring Hollow currently operates the diffuser, with compressed air, during late summer months when DO levels in the hypolimnion reach approximately 4 mg/L. Observations during oxygenation have identified changing DO addition rates during diffuser operation and changing DO depletion rates following termination of oxygenation. Future research should focus on developing a quantitative understanding of the changing rates as they are related to diffuser induced oxygen demand. / Master of Science

Studies On Surface Aeration In Circular Tanks

Patel, Ajey Kumar 09 1900 (has links)
Water is a fundamental need for existence of mankind. Only 0.01 % of total global water is readily available for human consumption as fresh water. The rapid increase in human population and consequent rise in urbanization and industrialization is producing a stress on this meager water resource. Water at the same time is a renewable resource, ie with suitable treatment it can be made re-useable. Aeration is one of the important processes employed in activated sludge process of the biological treatment units of wastewater. In this process the level of dissolved oxygen in the effluent is raised to the required amounts to decompose organic matters present in the effluent and thereby to reduce the BOD (biochemical oxygen demand) of the effluent by a physical means called “aeration process”. The aeration process consumes as much as 60-80% of total power requirements of wastewater treatment plants. Therefore, the efficiency in design of aeration process is required so that treatment and its power consumption can be economized. With the objective of optimizing the aeration process the present work in this thesis endeavors to develop an aeration which is efficient as well as economical. The various geometric parameters that affect the aeration process in mechanical surface aerators have been optimized. In the present work circular surface aeration tanks have been used. There are two types of circular tanks: Baffled and unbaffled. Separate optimal geometric parameters have been obtained for baffled and unbaffled circular tanks. With optimal geometric similitude scale up studies were done. Reynolds number and Froude number criteria has been found unsuitable for scaling oxygen transfer rates. Theoretical power per unit volume parameter is the most suitable scaling parameter for oxygen transfer rates in both baffled and unbaffled circular tanks. Baffled circular tanks are found to give better performance in terms of oxygen transfer rates as compared to unbaffled tanks. In contrast unbaffled tanks give better performance in terms of power consumption as compared to baffled circular tanks. General correlations have been developed for oxygen transfer rates for both baffled and unbaffled circular surface aerations tanks which incorporate all the geometric and dynamic parameters. These correlations help in the design of new treatment facilities as well as evaluating and up gradation of existing facilities. Power consumption studies have also been conducted on circular surface aeration tanks. Geometric parameters affect the power consumption significantly. Using the optimal geometric similarity conditions obtained for oxygen transfer rates the scale up studies for power consumption has also been done. Reynolds and Froude criteria are found to be giving scale effects for non dimensional power consumption parameter, power number. Theoretical power per unit volume parameter is found to be the scaling parameters for power number and a suitable correlation equation has been developed for baffled circular surface aeration tanks. General correlations have been developed for power number in baffled and unbaffled circular tanks. A novel type of self aspirating tube sparger system has been developed. It is like a bubble aerator with a rotor. The various geometric parameters that affect oxygen transfer rates have been optimized in baffled circular surface aeration tank. The optimal geometrically similar tanks have been used for scale up studies. Theoretical power per unit volume parameter is found to be the scaling parameter for oxygen transfer rates in circular surface aeration tanks with self aspirating sparger systems. Circular baffled tanks with a special sparger system gives very much higher oxygen transfer rates (as much as 5.7 times) as compared to circular tanks. The oxygen transfer rates data from literature also show lower values as compared to the system developed in this thesis. Geometrically similar unbaffled tanks have also been used with self aspirating sparger system. For same power consumption oxygen transfer rate in circular surface aeration tanks with self aspirating sparger system is higher as compared to circular tanks without self aspirating system. Mixing mechanisms in surface aeration tanks depend upon two different extreme length scales of time, namely macromixing and micromixing. Small scale mixing close to the molecular level is referred to as micromixing; whereas macromixing refers to the mixing on a large scale. The effect of geometrical parameters on macromixing time has been studied. The scaling parameters for macromixing and micromixing have been developed and simulation equations governing these time scales are also presented.

Factors contributing to the development of rancidity in ground pearl millet (Pennisetum americanum (L) Leeke) during storage

Kaced, Idir January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries

Investigation of the oxygen uptake of dried, remoistened soils

Funke, Berdell R. January 1961 (has links)
Call number: LD2668 .T4 1961 F87


ALMASOUM, AHMED ABDUL RAHMAN. January 1986 (has links)
Tomato plants (Lycopersicon esculentum Mill.) were grown in a greenhouse in Arizona in order to determine the effect of aeration, flooding, and exogenously applied benzyladenine (BA) on growth and cytokinin production at different growth stages. The structural changes in roots at different soil environments were also studied. Fresh and dry weight of roots and shoots and root exudate were collected at various stages of growth. Results showed that aerated plants significantly outperformed flooded and BA treated plants due to increased root and shoot output. The level of cytokinin in root exudate was higher during the early phase of vegetative growth. At the time of bud formation and anthesis, the level of cytokinin declined. In the vegetative stage, the competition between removed sinks and the rest of the shoot was reduced and, as a result, more cytokinin was believed to come from the roots to the shoots. Besides, additional carbohydrates were available to the roots. Determination of cytokinins in aerated plants showed a significant increase. However, in flooded plants, a smaller amount of cytokinin was detected. This is believed to be due to death of root apices, a major site for cytokinin production. Under experimental conditions, the application of BA to foliage of flooded plants had an adverse effect on growth of roots and shoot of tomato plants. However, a slight increase in cytokinin level was detected. Histological studies showed an increase in air-spaces (aerenchyma) in roots of flooded plants. This acclimation improved survival in inadequately aerated plants that were waterlogged.

Karaktärisering av hårdmetallpulvrets råvaror och dess påverkan på pulvrets flödesegenskaper

Bengtsson, David January 2015 (has links)
This thesis has been done at the powder department (GH) at AB Sandvik Coromant in Gimo. With a rheometer measurements has been made on raw materials and powder blends. The focus of this report has been to find correlations between raw material powders and press data, comparisons have also been made between raw materials and powder blends. The rheometer can show information of how a powder act in flow conditions, together with air and with pressure. Analyses has been done comparing the rheometer data with press parameters (for example: rejected orders, weight variations and the compaction pressure) with the goal to find correlations between the powders flow properties and the powders compaction in production. The measurements and analyses have been showing that the powder flow properties depends on the powders composition and that properties like flow rate, aeration and permeability varies between powder blends and batches of the same powder sort. It seems to exist a correlation between the pressure force and the flow rate of a raw material. This flow rate seems to belong together with the flow rate of the powder blend. No correlations were found between the rheometer measurements and press rejections, weight variations and hall flow values. The statistical analyses that has been used in this report consist of a few number of measured values and for the analyses to be statistic correct it is necessary to have a larger sample in the analyses.

Physical and chemical processes affecting forced ventilation of benzene and p-xylene in a desert soil

Van de Water, James Gordon, 1963- January 1989 (has links)
The rate at which volatile organic compounds (VOCs) are removed from the vadose zone by forced ventilation may be reduced by slow micro-scale processes such as diffusion through intra-aggregate and pore water and slow reactions at sorption sites located at the soil-water interface. Column experiments using benzene and p-xylene were performed in order to simulate cleanup of VOC's in the vadose zone by forced ventilation. Analytical solutions of the one-dimensional advection-dispersion equation coupled to mass transfer equations were fitted to the data. Parameter estimates were used in order to determine time scales of diffusion through water, desorption from, and sorption to, soil organic matter. Lower limits for the time scales for these processes were calculated to be on the order of minutes. Results indicate that these micro-scale processes reduce the rate of removal on the laboratory scale but may have no effect on the field scale.

Static pressure drop in a fixed bed of grain as affected by grain moisture content

Ahmed, Yousef Nagi (Assalimy) January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries

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