Long-term climatological data were used to evaluate the effectiveness of a drop/add management strategy to reduce groundwater use and effluent discharge in catfish ponds in the southeast U.S.. A drop/add approach is based on the creation of a storage volume in the pond for rainfall collection. The storage volume is created by allowing water level in the pond to decrease until some minimum level is reached. When the minimum level is reached, the pond is partly refilled, leaving the remaining volume available to capture incident precipitation. In this way, the role of precipitation in the water budget is increased. In the process, groundwater use and effluent release both become smaller. The data consisted of 45 year precipitation and evaporation records from Fairhope, AL; Clemson, SC; Stoneville, MS, Stuttgart, AR; and Thomsons, TX. The data were used in a water balance levee pond model that included precipitation, evaporation, infiltration, overflow, groundwater pumping, and draining. The model appeared to indicate that the drop/add management scheme is an effective strategy to reduce groundwater use and effluent discharge. The simulated results showed that variation of climate in the southeast U.S. was an important determinant of performance of the drop/add management scheme. At locations with positive P-0.8E, zero groundwater use could be achieved with low drop depths. At location with negative P-0.8E, zero groundwater use could be achieved for about 50% of the 45 simulated years. The model also indicated that effluent discharge cannot be avoided at most locations except at location with very low (negative) P-0.8E. The model also indicated that 65 to 100% of annual precipitation (depending on the P-0.8E?s of the locations) can be captured and used in the ponds. Rainwater contribution to the total water budget ranged from 90 to 100%. The sensitivity analysis showed that model sensitivity to pan coefficient and infiltration rate was affected by infiltration rate and pond water storage capacity (drop depth). The model was more sensitive to pan coefficient rather than to infiltration rate at lower infiltration rates and vice-versa.Both sensitivities of the model, however, increased when pond water deeper storage capacity was used.

The purpose of this study is to determine if a transition program has a greater success rate, as measured by GPA, number of students recycled, attendance, and conduct, than a traditional program of study for over age, first time ninth grade students by the end of first semester of the ninth grade. Some of the typical outcomes during the transition to high school from grade 8 to grade 9 are high failure rates, lack of Algebra I readiness, and poor attendance. These concerns contribute to drop-out rates and the level of competitiveness students will have when facing the workforce. This is a timely issue as we continue to address Standards of Learning (SOL) and No Child Left Behind (NCLB) Act and the initiatives to rethink our high schools as they attempt to prepare students for the ongoing changes of the economy, workforce, and expectations of colleges and universities. / Ph. D.

Computational fluid dynamics (CFD) modeling was used to predict the gas-solid hydrodynamics of fluidized beds. An Eulerian-Eulerian multi-fluid model and granular kinetic theory were used to simulate fluidization and to capture the complex physics associated therewith. The commercial code ANSYS FLUENT was used to study two-dimensional single solids phase glass bead and walnut shell fluidized beds. Current modeling codes only allow for modeling of spherical, uniform-density particles. Owing to the fact that biomass material, such as walnut shell, is abnormally shaped and has non-uniform density, a study was conducted to find the best modeling approach to accurately predict pressure drop, minimum fluidization velocity, and void fraction in the bed. Furthermore, experiments have revealed that all of the bed mass does not completely fluidize due to agglomeration of material between jets in the distributor plate. It was shown that the best modeling approach to capture the physics of the biomass bed was by correcting the amount of mass present in the bed in order to match how much material truly fluidizes experimentally, whereby the initial bed height of the system is altered. The approach was referred to as the SIM approach. A flow regime identification study was also performed on a glass bead fluidized bed to show the distinction between bubbling, slugging, and turbulent flow regimes by examining void fraction contours and bubble dynamics, as well as by comparison of simulated data with an established trend of standard deviation of pressure versus inlet gas velocity. Modeling was carried out with and without turbulence modeling (k-ϵ), to show the effect of turbulence modeling on two-dimensional simulations. / Master of Science

Este trabalho apresenta um estudo sobre o efeito de sombreamento em detectores de nêutrons, quando estes são utilizados em medidas de reatividade com a técnica de rod drop. O sombreamento pode ser entendido como uma mudança na eciência dos detectores, quando esta é dada em nêutrons detectados/ssão ocorrida no reator, sendo mais evidente nos detectores mais próximos ao banco sendo inserido. O método de análise, fundamentalmente teórica, baseou-se em simulações do reator IPEN/MB-01 utilizando o código CITATION e o programa MCNP. Em ambos os casos, os resultados são estáticos, mostrando os uxos neutrônicos apenas em duas situações: antes da inserção do banco, e após sua inserção. A reatividade, neste caso, é obtida utilizandose a expressão derivada da técnica de source jerk. Em adição ao estudo teórico, os dados de um experimento de rod drop realizado no reator IPEN/MB-01 também foram utilizados. Neste caso, a reatividade foi obtida com o método de cinética inversa, já que os dados experimentais são constituídos de valores que variam no tempo. Em todos os casos, fatores de correção para o efeito de sombreamento são propostos. / This work presents a study on the eect of shading in neutron detectors, when used in measures of reactivity with the rod drop technique. Shading can be understood as a change in the eciency of the detectors, when it is given in detected neutrons / ssion occurred in the reactor, more evident in the detectors closest to the bank being inserted. The method of analysis was based on simulations of reactor IPEN/MB-01, using the code CITATION and MCNP program. In both cases, the results were static, showing Neutronic ows in only two situations: before insertion of the control rod and after insertion. The measure of reactivity in this case was achieved using the expression derived from the source jerk technique. In addition to theoretical study, data from a rod drop experiment conducted in the reactor IPEN/MB-01 were also used. In this case, the reactivity was obtained using inverse kinetic method, since experimental data were set of values that vary with time. In all cases, correction factors for the shadowing eect have been proposed.

Vortex drop shafts are used to transport water or wastewater from over-stressed existing sewer systems to underground tunnels. During the plunge a large amount of air is entrained into the water and released downstream of the drop shaft into the tunnel. This air is unwanted and becomes costly to treat and move back to the surface. Determining the amount of air that will be entrained is a difficult task. A common method is to build a scale model and measure the air discharge and scale it back to prototype. This study investigated a possible relationship between the geometry of the drop structure, the water discharge and the amount of air entrained. The results have shown that air entrainment is still not entirely understood, however we are close to a solution. Using a relationship of the air core diameter, drop shaft length and terminal velocity of the water, a likely exponential relationship has been developed.

The point of the study is to investigate educational and vocational counselors' strategies on drop in calls. In order to answer the purpose, the issues concerning the educational and vocational counselors' strategies and guidance models/methods at drop-in calls investigated. Qualitative interviews were conducted with six educational and vocational counselors'. In the study it appears that the educational and vocational counselors' are unable to have any strategies for drop-in conversation because the applicant will come spontaneously and the educational and vocational counselors' lack information about the individual and its purpose of the interview. Guidance models/methods designed to facilitate for the applicant and give them a sense of understanding about them selves there environment and results in a clarification of the election, not often used during the drop-in calls.These are not often used due to the lack of time because the intention of the call is to provide with information to the applicant in as little time as possible. In an educational and vocational counselors’ perspective the guidance that is offered at drop-in calls defective.

The research discussed in this dissertation was conducted to understand drop formation of inkjet printing with inks containing polymer. Solutions containing a water soluble polymer, poly ethylene oxide (PEO), with different molecular weights and polydispersities were used as inks. A flash photographic technique was used to visualize the whole process of DOD drop formation of dilute polymer solutions. The effects of driving signal, frequency and liquid properties on drop speed, drop size, breakup time and the formation of satellites were studied in detail. The addition of PEO increases the shear viscosity at all molecular weights, but the change is small for dilute solutions. However, the addition of a small amount of PEO can have a significant effect on the DOD drop formation process, increasing breakup time, decreasing primary drop speed and decreasing the number of satellites in some cases. The effects depend on both molecular weight and concentration. At lower molecular weights (14k and 35k g/mol), the effect of PEO was small when the drop formation process for the dilute solution was compared with that of a Newtonian liquid having similar shear viscosity, and the effect of PEO was small even at concentrations large enough that the solution does not fall in the dilute regime. As molecular weight is increased, the effects of PEO on DOD drop formation increase significantly, and the effects of concentration become important. These effects are explained by the fluid elasticity which increases with increasing in molecular weight and concentration. When the liquid jets out of the nozzle, the polymer chains are stretched, and thus depart from their ideal coiled state. As a result, an elastic stress develops in the liquid column and resists capillarity-driven pinch off from the nozzle and is responsible for the decrease in drop speed and longer breakup time. DOD drop formation data were shown to correlate closely with effective relaxation time, proposed by Tirtaatmadja based on Rouse-Zimm theory. When driving voltage amplitude is 44.2 V, two important parameters (breakup time and primary drop speed) in DOD drop formation for solutions containing monodispersed PEO and aqueous solutions containing mixtures of monodispersed PEO were closely predicted by correlation equations involving effective relaxation time . A mixture rule was developed to calculate the relaxation time for mixtures of monodispersed PEO. However, for polydispersed PEO, effective relaxation time was based on viscous molecular weight since the molecular weight distributions of the polydispersed PEO were unknown. When breakup time was plotted versus effective relaxation time for 1000k g/mol PEO, the data did not lie on the same line as that for the 100k and 300k g/mol PEO. This is believed to be due to the molecular weight distributions of the polydispersed PEO. When more than one species are present, viscous average molecular weight does not adequately account for the long chain species making up the polymer sample. DOD drop formation dynamics is highly affected by the actuating waveform, including the driving voltage, waveform shape, and frequency. The effects of parameters (jetting frequency, voltage amplitude and the shape of waveform) characterizing the signal were investigated. The open time and first drop problem were also studied. Research in this dissertation gives a better understanding of DOD drop formation process of polymer solutions, which may lead to improvement of inkjet printing quality for a variety of industry inks and polymer micro scale deposition and patterning in large areas.

Eighty percent of all adolescents in Sweden aged 13-19 years are physically active in sports associations growing up during their childhood, however, far from everyone continues as they get older. The aim of this study is to increase the knowledge about sports associations views and perceptions regarding why adolescents quit physical activities and how they work to prevent this to occur. Furthermore, this study will examine the perceptions and opinions these sport associations have regarding recruitment of adolescents for coaching and other positions within their association. The data in this study was collected from nine semi-structured interviews with representatives from sports associations in the county of Umeå. The results from the data analysis indicates that the sport associations seems to be aware of this drop out among adolescents and that the reason for this phenomena is complex and individual. Despite this, little action seemed to be taken among these sport associations in order to try to keep young individuals physically active within the club or with recruitment of these individuals as coaches, even if the sport associations considered it as a good solution to the problem. The main conclusion of this study is that if sport associations are in need of preventing youth drop out they have to increase their activities for preventing it. Furthermore they need to start seeing adolescents as resources to the sport association.

Eidgenössische Techn. Hochsch, Diss--Zürich, 2000.

Este trabalho apresenta um estudo sobre o efeito de sombreamento em detectores de nêutrons, quando estes são utilizados em medidas de reatividade com a técnica de rod drop. O sombreamento pode ser entendido como uma mudança na eciência dos detectores, quando esta é dada em nêutrons detectados/ssão ocorrida no reator, sendo mais evidente nos detectores mais próximos ao banco sendo inserido. O método de análise, fundamentalmente teórica, baseou-se em simulações do reator IPEN/MB-01 utilizando o código CITATION e o programa MCNP. Em ambos os casos, os resultados são estáticos, mostrando os uxos neutrônicos apenas em duas situações: antes da inserção do banco, e após sua inserção. A reatividade, neste caso, é obtida utilizandose a expressão derivada da técnica de source jerk. Em adição ao estudo teórico, os dados de um experimento de rod drop realizado no reator IPEN/MB-01 também foram utilizados. Neste caso, a reatividade foi obtida com o método de cinética inversa, já que os dados experimentais são constituídos de valores que variam no tempo. Em todos os casos, fatores de correção para o efeito de sombreamento são propostos. / This work presents a study on the eect of shading in neutron detectors, when used in measures of reactivity with the rod drop technique. Shading can be understood as a change in the eciency of the detectors, when it is given in detected neutrons / ssion occurred in the reactor, more evident in the detectors closest to the bank being inserted. The method of analysis was based on simulations of reactor IPEN/MB-01, using the code CITATION and MCNP program. In both cases, the results were static, showing Neutronic ows in only two situations: before insertion of the control rod and after insertion. The measure of reactivity in this case was achieved using the expression derived from the source jerk technique. In addition to theoretical study, data from a rod drop experiment conducted in the reactor IPEN/MB-01 were also used. In this case, the reactivity was obtained using inverse kinetic method, since experimental data were set of values that vary with time. In all cases, correction factors for the shadowing eect have been proposed.