Cake filtration is a unit operation to separate solids from fluids in industrial processes. The build up of a filter cake is usually accompanied with a decrease in overall permeability over the filter leading to an increased pressure drop over the filter. For an incompressible filter cake that builds up on a homogeneous filter cloth, a linear pressure drop profile over time is expected for a constant fluid volume flow. However, experiments show curved pressure drop profiles, which are also attributed to inhomogeneities of the filter (filter medium and/or residual filter cake). In this work, a mathematical filter model is developed to describe the relationship between time and overall permeability. The model considers a filter with an inhomogeneous permeability and accounts for fluid mechanics by a one-dimensional formulation of Darcy's law and for the cake build up by solid continuity. The model can be solved analytically in the time domain. The analytic solution allows for the unambiguous inversion of the model to determine the inhomogeneous permeability from the time resolved overall permeability, e.g. pressure drop measurements. An error estimation of the method is provided by rewriting the model as convolution transformation. This method is applied to simulated and experimental pressure drop data of gas filters with textile filter cloths and various situations with non-uniform flow situations in practical problems are explored. A routine is developed to generate characteristic filter cycles from semi-continuous filter plant operation. The model is modified to investigate the impact of non-uniform dust concentrations.

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

Annular flow is an important flow regime in many industrial applications. The need for a better understanding of this flow regime is driven by the desire to improve the design of many terrestrial and space-based systems. Annular two-phase flow is frequently present in the drilling, production and transportation of oil and natural gas, boilers and condensers, and in heating and refrigeration systems. The flow regime is also important for the refueling of space vehicles, and heating and refrigeration systems for space use. Past studies on annular flow have dealt with varying the gas or liquid Reynolds numbers and studying the effect of such changes on the flow regimes and pressure drops. The effect of two other relevant dimensionless groups, namely the gas-to-liquid density ratio and the gas-to-liquid viscosity ratio, on the film characteristics are noticeably absent. As well, with the increased interest in the space environment, studies on the effect of the gravitational acceleration on two-phase flow would be beneficial. The effect of the gas density and the gravitational acceleration on the annular flow average film thickness and frictional pressure drop are examined. The film thickness was measured using two-wire conductance probes. Experimental data were collected in microgravity and hypergravity aboard the Novespace Zero-G Airbus microgravity simulator and normal gravity data were collected at the University of Saskatchewan. Data were collected for a range of annular flow set points by changing the liquid and gas mass flow rates. The liquid-to-gas density ratio was examined by collecting annular flow data using helium-water and air-water. The gravitational effect on the film thickness characteristics was examined by collecting the data during the microgravity and pull-up (hypergravity) portions of each parabolic flight. A direct comparison is possible between the normal gravity data and the microgravity data, due to the matching of the liquid and gas mass flow rates and the flow regime. The reduction in gravity causes the average film thickness to increase between two and four times from the normal gravity values. The microgravity average frictional pressure drop is within approximately 20% of the normal gravity pressure drop for the same flow conditions. For all gravity levels, the air-water and the helium-water flows give similar results, for both average film thickness and frictional pressure drop, when based on the specific energy of the gas. The hypergravity average film thickness results are larger than at normal gravity for the same flow conditions. However, no flow regime map exists for the hypergravity condition, so the similarity of the flow regime cannot be confirmed. The hypergravity flow appears more chaotic, and may be in the transition from a churn type flow. The average frictional pressure drop is increased by approximately 20% due to the increase in the gravitational acceleration. New non-dimensional equations, which include the effect of the gas density, are presented for each gravity level to predict the average film thickness and the average frictional pressure drop.

Syftet med föreliggande studie är att undersöka hur skolledare, lärare och elever på en gymnasieskola i södra Sverige resonerar om bedömning och betygsättning samt att ta reda på hur betygsfördelningen ser ut vid antagning till och avgång från gymnasiet för årskullen 2008-2011 på den aktuella skolan. Genom insamling av listor med jämförelsetal för de elever som antagits 2008 och över jämförelsetal vid avgång 2011 har diagram över procentuell fördelning av jämförelsetal skapats. Intervjuer med en skolledare, tre gymnasielärare samt tre elever i årskurs tre har gjorts. Min studie visar att det inte finns någon nedskriven bedömningspolicy på den aktuella gymnasieskolan samt att det i relativt stor utsträckning är upp till varje enskild lärare att hitta sätt att förklara bedömning och betygssättning för eleverna. De intervjuade lärarna hade olika strategier för att nå förståelse hos elever för bedömning och betygssättning. Resultaten av studien indikerar bland annat en fortsatt trend på det estetiska programmet av att höja sina betyg under de tre åren samtidigt som 17,3 % av eleverna på detta program ut med samlat betygsdokument 2011, ej behöriga att söka vidare till universitet eller högskola. 7,75 % av eleverna på naturvetenskapligt program går ut med samlat betygsdokument 2011 vilket är en liten bättring från 2003 då 12,9 % gick ut ej behöriga att söka vidare. Motsvarande resultat för eleverna på samhällsprogrammet är 6,84 % ej behöriga att söka vidare från årskullen 2011 jämfört med 8,84 % ej behöriga året 2003. En slutsats som kan dras av studien är att en betydande andel elever hoppar av gymnasiet eller går ut med samlat betygsdokument 2011 samt att bilden skolledare, lärare och elever har av bedömning i allmänhet och vilken bedömning som sker på den aktuella skolan i synnerhet skiljer sig åt.

Annular flow is an important flow regime in many industrial applications. The need for a better understanding of this flow regime is driven by the desire to improve the design of many terrestrial and space-based systems. Annular two-phase flow is frequently present in the drilling, production and transportation of oil and natural gas, boilers and condensers, and in heating and refrigeration systems. The flow regime is also important for the refueling of space vehicles, and heating and refrigeration systems for space use. Past studies on annular flow have dealt with varying the gas or liquid Reynolds numbers and studying the effect of such changes on the flow regimes and pressure drops. The effect of two other relevant dimensionless groups, namely the gas-to-liquid density ratio and the gas-to-liquid viscosity ratio, on the film characteristics are noticeably absent. As well, with the increased interest in the space environment, studies on the effect of the gravitational acceleration on two-phase flow would be beneficial. The effect of the gas density and the gravitational acceleration on the annular flow average film thickness and frictional pressure drop are examined. The film thickness was measured using two-wire conductance probes. Experimental data were collected in microgravity and hypergravity aboard the Novespace Zero-G Airbus microgravity simulator and normal gravity data were collected at the University of Saskatchewan. Data were collected for a range of annular flow set points by changing the liquid and gas mass flow rates. The liquid-to-gas density ratio was examined by collecting annular flow data using helium-water and air-water. The gravitational effect on the film thickness characteristics was examined by collecting the data during the microgravity and pull-up (hypergravity) portions of each parabolic flight. A direct comparison is possible between the normal gravity data and the microgravity data, due to the matching of the liquid and gas mass flow rates and the flow regime. The reduction in gravity causes the average film thickness to increase between two and four times from the normal gravity values. The microgravity average frictional pressure drop is within approximately 20% of the normal gravity pressure drop for the same flow conditions. For all gravity levels, the air-water and the helium-water flows give similar results, for both average film thickness and frictional pressure drop, when based on the specific energy of the gas. The hypergravity average film thickness results are larger than at normal gravity for the same flow conditions. However, no flow regime map exists for the hypergravity condition, so the similarity of the flow regime cannot be confirmed. The hypergravity flow appears more chaotic, and may be in the transition from a churn type flow. The average frictional pressure drop is increased by approximately 20% due to the increase in the gravitational acceleration. New non-dimensional equations, which include the effect of the gas density, are presented for each gravity level to predict the average film thickness and the average frictional pressure drop.

Syftet med studien var att undersöka huruvida självskattad känsla av skoltrötthet samvarierar med begriplighet, hanterbarhet och meningsfullhet vilka är delkomponenter i KASAM, känsla av sammanhang. Deltagarna var elever som studerar studie- respektive yrkesinriktade gymnasieprogram vid en gymnasieskola i Mälardalen (N = 97). Köns- och studieinriktningsdifferenser samt elevers egna kommentarer kring skoltrötthet var även av intresse. En tvådelad enkät konstruerades och delades ut till eleverna. Enkäten innehöll dels ett självskattningsformulär för att mäta känsla av skoltrötthet och dels Antonovsky´s livsfrågeformulär som mäter KASAM. Begreppet skoltrötthet kom på grund av lågt alfavärde att splittas till lärtrötthet, skolka för att orka, utmattad efter en skoldag samt känsla av otillräcklighet. Resultatet visade att elevers känsla av lärtrötthet samvarierade med meningsfullhet i skolan. Vidare fanns en svag tendens att lärtrötthet även samvarierade med hanterbarhet. Meningsfullhetskomponenten var en signifikant prediktor för lärtrötthet. Begriplighet fick signifikant högre skattning av männen. Inga signifikanta studieinriktningsskillnader förelåg.

This research presents an experimental study of the formation of drops of suspensions consisting of a viscous liquid and spherical, neutrally buoyant, noncolloidal particles. Pendant drop formation and low Reynolds number jetting of suspensions are investigated, as is the transition between the two. Throughout, the particles utilized are on the order of 100 μm and the orifice from which the drops are formed is on the order of 1 mm. The presence of the particulate phase causes the structure at pinch-off in the pendant drop regime to change noticeably from that of pure liquids. Thick cone-like structures, termed "spindles" here, form at either end of the slender thread and are the result of particle motions during necking. These spindles become more pronounced with increasing particle concentration. Depending on particle concentration, the particles can have either a destabilizing effect (low concentration) on drop formation or a stabilizing one (high concentration). At low concentrations, the particles lead to earlier rupture of the thread and much shorter jet lengths, while at elevated concentrations the particles stabilize the thread after rupture and lead to fewer satellite drops as well as induce jetting at lower flower rates. A two-stage model has been proposed to describe the necking process for particle-laden suspensions in the pendant drop regime. The first stage occurs when the thread is thick relative to the particles and the effect of the particles can be attributed solely to a change in the effective viscosity of the mixture. The second stage occurs nearer pinch-off when the thread has thinned to only a few particle diameters. In this stage the individual particle motions within the thread determine the behavior and the thread ultimately ruptures over a region of the thread devoid of particles.

A study of the pressure drop characteristics of the flow of highly viscous fluids through small diameter orifices was conducted to obtain a better understanding of hydraulic fluid flow loops in vehicles. Pressure drops were measured for each of nine orifices, including orifices of nominal diameter 0.5, 1 and 3 mm, and three thicknesses (nominally 1, 2 and 3 mm), and over a wide range of flow rates (2.86x10sup-7/sup Q 3.33x10sup-4/sup msup3/sup/s). The fluid under consideration exhibits steep dependence of the properties (changes of several orders of magnitude) as a function of temperature and pressure, and is also non-Newtonian at the lower temperatures. The data were non-dimensionalized to obtain Euler numbers and Reynolds numbers using non-Newtonian treatment. It was found that at small values of Reynolds numbers, an increase in aspect ratio (length/diameter ratio of the orifice) causes an increase in Euler number. It was also found that at extremely low Reynolds numbers, the Euler number was very strongly influenced by the Reynolds number, while the dependence becomes weaker as the Reynolds number increases toward the turbulent regime, and the Euler number tends to assume a constant value determined by the aspect ratio and the diameter ratio. A two-region (based on Reynolds number) model was developed to predict Euler number as a function of diameter ratio, aspect ratio, viscosity ratio and generalized Reynolds number. This model also includes data at higher temperatures (20 and le; T and le; 50supo/supC) obtained by Mincks (2002). It was shown that for such highly viscous fluids with non-Newtonian behavior at some conditions, accounting for the shear rate through the generalized Reynolds number resulted in a considerable improvement in the predictive capabilities of the model. Over the laminar, transition and turbulent regions, the model predicts 86% of the data within and plusmn25% for 0.32 l/d (orifice thickness/diameter ratio) 5.72, 0.023 and beta; (orifice/pipe diameter ratio) 0.137, 0.09 Resubge/sub 9677, and 0.0194 and mu;subge/sub 9.589 (kg/m-s)

The main objective of this thesis is to develop models for the power distribution network of high performance gigascale chips. The two main concerns in distributing power in a chip are voltage drop and electromigration-induced reliability failures. The voltage drop on the power distribution network is due to IR-drop and simultaneous switching noise. IR-drop is the voltage drop due to current passing through the resistances of the power distribution network. Simultaneous switching noise is due to varying current passing through the inductances of the power distribution network. Compact physical models are derived for the IR-drop and electromigration for different types of packages. These chip-package co-design models enable designers in the early stages of the design to estimate the on-chip interconnect resources, and also to choose type and size of the package required for power distribution. Modeling of the simultaneous switching noise requires the simulation of a large circuit with thousands of inductances. The main obstacle challenging the simulation of a simultaneous switching noise circuit model is the computing resources required to solve the dense inductance matrix. In this work, a new relative inductance matrix is introduced to solve massively coupled RLC interconnects. It is proven that the analysis using this method is accurate for a wide frequency range and all configurations. Using the new inductance matrix makes the circuit simulations significantly faster without losing accuracy.

In this study, the flow plates of micro methanol fuel cells are designed and fabricated in-house through MEMS(Micro-Electro-Mechanical System) technology with deep UV lithography manufacturing processes (SU-8 photoresist) and micro electroforming manufacturing processes. The thesis investigates methanol and water crossover in a micro DMFC for serpentine flow field configuration. Experiments are conducted through various experiments with different operating conditions for the anode flow rate (2-10 sccm), cathode flow rate (100-500 sccm), methanol concentration (1, 2 and 3M), and temperature (25, 50 and 75¢J). Experimental results are presented in the form of polarization VI curves and PI curves under the above operating conditions. The experimental results show that the methanol and water crossover flux increases with increases in cell temperatures, methanol concentration and anode pressure drop. It is found that the fuel efficiency of the DMFC is closely related to the methanol crossover. Further examination of the relationship between the methanol crossover and cell performance reveals the possibility of reducing the methanol crossover by optimizing the anode flow rate.