Hydraulic fracturing is a popular stimulation method in tight gas and shale gas reservoirs that uses a viscous fluid to fracture the reservoir rock and uniformly transport proppant to create a highly conductive path that is kept open by the proppant after fracturing. This method is used to improve the productivity of the otherwise low permeability reservoirs. Hydraulic fracturing, though in general beneficial, is a complex process that has a number of challenges in fracturing design and execution. This research focuses on studying the damage caused by the fracturing fluid (gel) to the fracture and the conditions to remove the damage. Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracturing fluids. The fracturing fluid gets dehydrated under pressure leaving behind a highly concentrated unbroken residue called filter cake which causes permeability impairment in the proppant pack, resulting in low fracture conductivity and decreased effective fracture length. This study seeks to characterize filter cakes. By measuring its thickness and with the leak off volume, the concentration and yield stress of the filter cake can be estimated. The thickness of the filter cake was measured with a precise laser profilometer. Correlations are proposed to estimate filter cake properties (thickness, concentration and yield stress) based on pumping conditions (pump rate, time and net pressure) and rock properties. With these properties known, a required flow back rate of the reservoir fluid can be estimated to clean up the filter cake modeled as a non-newtonian fluid exhibiting a yield stress. Typical field conditions were referenced and scaled down in the lab to closely represent the field conditions. Recommendations are provided on gel damage based on the observation of the study.

The main objective was to determine the variation of physical properties of different cake formulations during baking in microwave and infrared-microwave combination ovens. In the first part of the study, rheological and dielectric properties of cake batter with different formulations were determined. Different concentrations of fat and different types of emulsifier and fat replacer were used. The variation of formulation had a significant effect on the apparent viscosity of the cake batter. Cake batter was found to show shear thinning and time independent behaviour for all formulations. Dielectric properties of cake batter were dependent on formulation, frequency and temperature. In the second part of the study, physical properties (dielectric properties, volume, texture, color and porosity) of cakes baked in microwave and infrared-microwave combination oven were determined. In addition, starch gelatinization during baking was investigated. For comparison, cakes were also baked in conventional oven. Formulation and baking time were found to affect physical properties and gelatinization degree of cakes. Addition of fat to the formulation was found to increase the dielectric properties and gelatinization degree of microwave and infrared-microwave combination baked cakes. For both microwave and combination baking, cake samples with SimplesseTM had the highest volume but the firmest texture. Addition of maltodextrin resulted in a more uniform structure for infrared-microwave combination baking. There was insufficient gelatinization in microwave baked cakes ranging from 70 to 78% depending on fat content. The gelatinization degree ranged from 88 to 93% in conventionally baked cakes. Combining infrared with microwaves increased gelatinization degree (80-90%).

The main objective of this study was to design gluten free rice cakes containing different gums and an emulsifier for baking in infrared (IR)-microwave combination oven. In the first part of the study, the effects of different gums (xanthan, guar, xanthan-guar blend, &amp / #954 / -carrageenan, locust bean, hydroxypropyl methylcellulose (HPMC) and xanthan-&amp / #954 / -carrageenan blend) and emulsifier blend (PurawaveTM) on physical properties of cake batters were investigated. In the second part of the study, weight loss, specific volume and texture of the cakes baked in different ovens were determined. Macro and micro-structures of the cakes were investigated both qualitatively and quantitatively by using image analysis and Scanning Electron Microscopy (SEM). In the last part of the study, Response Surface Methodology (RSM) was used to optimize IR-microwave baking conditions and formulation of the cakes. Power law and Casson models were suitable to explain the rheological properties. Xanthan and xanthan-guar gum blends resulted in higher apparent viscosities as compared to other gums. Gum types affected the dielectric properties and gelatinization enthalpies of cake batter. Emulsifier addition increased the volume and porosity but decreased the firmness of the cakes baked in IR-microwave combination oven. More porous cakes were obtained when xanthan and xanthan-guar gum blend were used. Baking method was found to be important in affecting porosity, pore size distribution and microstructure of the cakes. The highest quality gluten-free rice cakes were obtained when the formulation contained xanthan gum and 5.38% emulsifier and baked using 40% microwave power, 60% halogen lamp power for 7 min in IR-microwave combination oven. In addition, baking time was reduced by 76.7% as compared to conventional baking.

<p>ABSTACT</p><p>INSTITUTION: Institutionen för pedagogik</p><p>Avdelningen för bild</p><p>Växjö universitet</p><p>ADRESS: 351 95 Växjö</p><p>TELEFON: 0470-70 80 00</p><p>HANDLEDARE: Emilie Karlsmo</p><p>TITEL: Bake a wish- iscensättningar av den lyckliga</p><p>hemmafrun</p><p>ENGELSK TITEL: Bake a wish- stagings of the happy housewife</p><p>FÖRFATTARE: Malin Nilsson</p><p>ADRESS: Stallvägen 46</p><p>352 56 Växjö</p><p>TELEFON: 070-52 29 572</p><p>TYP AV UPPSATS: C-uppsats</p><p>VENTILERINGSTERMIN: Ht 2008</p><p>Uppsatsen behandlar likheter mellan bilder hämtade från 2008 och 1950-talet för att finna om bilderna från 2008 är iscensättningar av 1950-talet.</p><p>Genom bildundersökningar och semiotiska bildanalyser av bilder i A piece of cake (2008), Husmoderns köksalmanack (1950-59) och Anne Taintors collage, undersöker uppsatsen om A piece of cake refererar till 1950-talet, och om det har skett några förskjutningar.</p><p>Författaren framhåller att det finns en del likheter, framförallt mellan A piece of cake och bilderna i Anne Taintors collage, samt att likheterna i förhållande till olikheterna tyder på en förändring av kvinnan som motiv.</p>

Carcinogenic health concerns over arsenic in drinking water caused the USEPA to reduce the maximum contaminant level (MCL) from 50 to 10 ppb, effective on January 23, 2006. This has forced many smaller utilities into expensive treatment or discontinuation of water distribution. Researchers throughout the world are working to develop an inexpensive method for arsenic removal to meet this MCL. Aluminum silicates, or zeolites, are naturally occurring ionic sorbents. Modification of a zeolite may enhance adsorption capacities and ion selectivity. This research investigates the arsenic adsorption capacities of a modified Chabazite. This adsorption, coupled with a hollow fiber, microfiltration membrane substrate, allows for the use of finer zeolite particles. Powdered zeolite creates a cake layer on the filtration surface through which the arsenic solution must filter. The research goal was to develop an overall mathematical model for the adsorption of arsenic through the adsorption equilibrium isotherms, the cake layer, and the microfiltration operational settings. Baseline adsorption isotherms where performed in distilled water. Solutions containing counter ions were then used to determine any counter-effects. The final isotherms were found using dechlorinated tap water, which is similar to many groundwaters found in the United States. Various runs were used to determine the most efficient modification and loading rate.Initial characterization of the membrane system defined membrane permeability and inherent arsenic rejection. Variable mass loading in both deadend and crossflow filtration determined that the cake layer was not compressible due to linear pressure increases. This process also determined the maximum cake layer permissible hydraulically on the membrane surface. Membrane system operational characteristics and arsenic dosing were chosen to adhere to these parameters as well as the adsorption isotherms. Adsorption runs were conducted which varied the flux through the membrane, the arsenic feed concentration, and the cake layer thickness. Through the data collected, a mathematical model based on irreversible adsorption was developed. This novel approach to arsenic removal and the predictive mathematical model can be used as an effective method for removal of aqueous arsenic, and may provide small water utilities with a cost effective way to meet the recommended new MCL.

ABSTACT INSTITUTION: Institutionen för pedagogik Avdelningen för bild Växjö universitet ADRESS: 351 95 Växjö TELEFON: 0470-70 80 00 HANDLEDARE: Emilie Karlsmo TITEL: Bake a wish- iscensättningar av den lyckliga hemmafrun ENGELSK TITEL: Bake a wish- stagings of the happy housewife FÖRFATTARE: Malin Nilsson ADRESS: Stallvägen 46 352 56 Växjö TELEFON: 070-52 29 572 TYP AV UPPSATS: C-uppsats VENTILERINGSTERMIN: Ht 2008 Uppsatsen behandlar likheter mellan bilder hämtade från 2008 och 1950-talet för att finna om bilderna från 2008 är iscensättningar av 1950-talet. Genom bildundersökningar och semiotiska bildanalyser av bilder i A piece of cake (2008), Husmoderns köksalmanack (1950-59) och Anne Taintors collage, undersöker uppsatsen om A piece of cake refererar till 1950-talet, och om det har skett några förskjutningar. Författaren framhåller att det finns en del likheter, framförallt mellan A piece of cake och bilderna i Anne Taintors collage, samt att likheterna i förhållande till olikheterna tyder på en förändring av kvinnan som motiv.

The object of this research was to determine if an acceptable angel food cake alternative could be produced that had reduced calories and sucrose content. This was accomplished through replacing sucrose in meringue, angel food cake batter, and baked angel food cakes with polydextrose and either sucralose, acesulfame-K, or Rebaudioside A at different replacement levels (25, 50, 75, 100%). Meringue and cake batter properties were measured using rheological techniques. Baked angel food cakes were analyzed based on height, weight loss, moisture content, color, and TPA analysis. With meringue batter, 100% sucrose replacement was unacceptable since undissolved polydextrose made analyzing and end products impractical. While 75% sucralose and acesulfame-K sucrose replacement exhibited comparable air incorporation to the sucrose control in cake batter, baked angel food cakes showed a decrease in functional properties. Polydextrose was likely the cause. 25% sucralose and acesulfame-K sucrose replacement were no different from sucrose cakes in regards to height, overall textural appearance, crumb pore size, and hardness. These cakes resulted in an overall calorie reduction of 18.7%. In every experiment, Rebaudioside A replacement treatments exhibited trends opposite of sucralose and acesulfame-K treatments. Rebaudioside A treatments performed the worst for rheological properties and TPA analysis.

Filter cake characterization is very important in drilling and completion operations. Heterogeneity of the filter cake plays a key role in the design of chemical treatments needed to remove the filter cake. The objectives of this study are to characterize the filter cake under static and dynamic conditions, evaluate the using of polylactic acid and chelating agents to remove calcium carbonate-based filter cake, assess glycolic acid to remove Mn3O4-based filter cake, and evaluate ilmenite as a weighting material for water-based drilling fluid. In order to characterize the filter cake, computer tomography (CT) was used in combination with the scanning electronic microscopy (SEM) to analyze the filter cake. A modified HPHT filter cell was developed to perform the filtration tests. A see-through-cell was used to check the compatibility of different chemicals that were used to remove the filter cake. The results obtained from the CT scan showed that the filter cake was heterogeneous and contained two layers with different properties under static and dynamic conditions. Under static conditions, the formation of filter cake changed from compression to buildup; while under dynamic conditions, the filter cake was formed under continuous buildup. Polylactic acid was used as a component of the drilling fluid components and the results obtained showed that the drill-in fluid had stable rheological properties up to 250˚F over 24 hrs. The removal efficiency of the filter cake was nearly 100% and the return permeability was about 100% for Indiana limestone and Berea sandstone cores, when using a weight ratio of polylactic acid to calcium carbonate 3 to 1. GLDA (pH 3.3) and HEDTA (pH 4) can be used to remove the filter cake in one step without using α-amylase enzyme solutions. GLDA (20 wt% in a 200 g solution and pH of 3.3) and HEDTA (20 wt% in a 200 g solution and pH 4) had 100% removal efficiency of the filter cake using Indiana limestone and Berea sandstone cores. Chelate solutions, GLDA (pH of 3.3 - 13) and HEDTA (pH of 4 and 7) were incompatible with α-amylase enzyme solutions over a wide range of temperatures. CT results showed that no formation damage was observed when using chelating agents as a breaker to remove the calcium carbonate filter cake. Manganese tetraoxide-based filter cake had a removal efficiency of 85% after 20 hrs soaking with glycolic acid (5 wt%) after soaking with α-amylase for 24 hrs, and 89% after reaction with acid mixture (1 wt% HCl and 7 wt% glycolic acid) for 16 hrs. for both methods, the retained permeability was 100% for Indiana limestone cores and 120% for Berea sandstone cores, which indication maximum productivity of these formations. Ilmenite-based filter cake was ideal for HPHT applications, 0.2 in. thickness and 12 cm3 filtrate under dynamic conditions. The filtrate volume was reduced by adding a minor amount of CaCO3 solids that improved the particles packing. No sag problem was observed when using the micronized ilmenite in water-based drilling fluids. Ilmenite has a negative zeta potential in alkaline media and had a stable dispersion in water at pH > 7.

The main objective of this study was to optimize processing conditions during halogen lamp-microwave combination baking of cake by using Response Surface Methodology. It was also aimed to compare quality of products baked in microwave-halogen lamp combination oven, halogen lamp oven, microwave oven and conventional oven. In the first part of the study, as independent variables, baking time for conventional oven / microwave power and baking time for microwave oven / halogen lamp power and baking time for halogen lamp oven and microwave power, halogen lamp power and baking time for halogen lamp-microwave combination oven were used. Weight loss, specific volume, firmness and color of the cakes were measured during the study. Cakes baked in conventional oven at 175&deg / C for 24 minutes were determined as the control cakes. Weight loss of cakes increased with increasing independent variables for all oven types. Specific volume and firmness of cakes increased with increasing microwave power, but decreased with upper halogen lamp power. Color formation was achieved in the combination baking but not as much as in the conventional baking. Response Surface Methodology was used to optimize the baking conditions in the second part of the study. Upper and lower halogen lamp powers, microwave power and baking time were used as independent variables. Optimum processing conditions were found as 60% for upper halogen lamp power, 70% for lower halogen lamp power, 30% for microwave power and 5 minutes for baking time. Cakes baked at optimum baking conditions had comparable quality with conventionally baked ones, except color. In short, by the usage of halogen lamp-microwave combination oven it was possible to obtain high quality cakes by reducing of conventional baking time about 79%.

Solid-liquid contact angle is an important parameter in many particulate processes of the mineral, ceramic and chemical industries. In particular, modification of the contact angle through surface active agents plays a crucial role in froth flotation of minerals. In the case of flat solid surfaces, direct measurement of the contact angle is possible. However, such flat surfaces can not be obtained with finely divided solids typically encountered in flotation applications. Then, indirect methods based on powder beds as thin layers of powders deposited on glass plates or packed columns are used for the determination of apparent contact angles. This thesis presents an alternative novel method based on the capillaric dewatering of filter cakes for the measurement of the receding contact angle and correlates the contact angles measured as such with column wicking and micro-flotation test results of zircon and rutile mineral particles. The experimental procedure is simple and fast. The results have proven that the proposed method is reliable and give a good measure of the contact angle in the absence and presence of surface active non-wetting agents.