This study aims to investigate the effect of elastic properties of viscoelastic polymer solutions on the microscopic sweep efficiency in enhanced oil recovery (EOR) operations. The effect of elasticity was studied as isolated from the shear viscosity effect using polymer blends with identical shear viscosity behavior but different elastic characteristics. Oil displacement results were compared and the individual effect of elasticity on the sweep efficiency was investigated. A detailed rheological characterization of the polymer solutions was done to measure their viscoelastic properties. A series of polymer flooding experiments were performed using a radial core holder. Results of the experiments indicated that the sweep efficiency of a polymeric fluid could be effectively improved by adjusting the molecular weight distribution (MWD) of the solution at constant shear viscosity and polymer concentration. An attempt was made to find a rheological parameter of polymer solutions that correlates better with the resultant oil recovery. / Petroleum Engineering

No description available.

Rotors are a crucial component of VTOL(vertical take-off and landing) devices like unmanned aerial vehicles (UAVs) or helicopters, etc., By generating a rotational force, they create the necessary thrust to lift and maneuver the vehicle in the air. In recent years, there has been a growing emphasis on developing rotor designs that are more efficient and effective for eVTOL. This has led to the emergence of several unconventional swept rotor designs that can improve aerodynamic and aeroacoustic performance. The present thesis aims to investigate the impact of achieving a balanced sweep distribution across a rotor blade and how it affects aerodynamic performance. The study explores the potential benefits and drawbacks of unconventional swept rotor designs and compares their performance curves to traditional straight rotor designs. The investigation begins with an overview of rotor design criteria and literature on swept rotor designs. A comprehensive design and analysis of the aerodynamic performance of various rotor designs are conducted using NASA's OpenVSP and VSPAero, a low-fidelity solver that implements the Vortex lattice method. The results are then compared with wind tunnel experiments. Based on the load distribution analysis of multiple sweep designs, it is noted that swept rotors exhibit decreased performance at lower advance ratios. However, as the speed or advance ratio increases, the overall performance of swept rotors significantly improves. This conclusion is drawn from the load distribution data obtained for each blade of the rotors, and by comparing the figure of merit (FOM) of various designs. / Master of Science / Picture this: a sleek unmanned aerial vehicle (UAV) soaring through the air, its Propellers whirring efficiently and quietly. What makes this possible? The answer lies in the design of the rotors themselves. Rotors are critical components of UAVs, providing the necessary thrust to lift and maneuver the vehicle in the air. And with the growing demand for more efficient and effective eVTOLs (Vertical take-off and Landing) vehicles, unconventional swept rotor designs have emerged as game-changers in the industry. The present thesis delves into the impact and effects of Parametric swept designs on rotor aerodynamic performance. The study seeks to uncover the potential benefits and drawbacks of these designs and compare their performance curves to traditional straight rotor designs. The study starts by looking at how rotors are designed and what others have done with similar designs. Various rotor designs have been thoroughly examined in terms of their aerodynamic characteristics using NASA's OpenVSP and VSPaero, a low-fidelity solver that uses the Vortex lattice method. To verify the tools, this data are compared with wind tunnel tests. Due to its cheap computing cost, OpenVSP makes it possible to investigate these discoveries in an economical manner. According to the results, swept rotors perform better at higher speeds than conventional rotors.

Deciphering the genetic basis of phenotypic diversity is one of the central aims of biological research. Domestic animals provide a unique opportunity for making substantial progress towards this goal. Intense positive selection has lead to a rich reservoir of phenotypes and underlying genotypes that can be interrogated using genetic tools to gain insight into the genetic basis of phenotypic diversity. The dog is the most phenotypically diverse mammal. It was domesticated from the grey wolf 11-30,000 years ago. After domestication, a period of intense breeding has lead to the massive phenotypic diversity seen amongst dog breeds today. These two phases of strong positive selection at domestication and at breed creation are likely to have left their signature on the genome. In this thesis, we have analysed genome-wide patterns to detect genomic regions involved in selection in both of these phases. We used whole genome sequences from 60 dogs and 12 wolves, to detect dog domestication selective sweeps. We find evidence for genes involved in memory formation, neurotransmission and starch digestion. To decipher the genetic signals underlying breed diversity, we used genome-wide genotype data from >170,000 SNPs in 509 dogs from 46 different breeds. We find evidence for genes under selection in many breeds, and only a few breeds. In addition, we identify novel sweeps underlying morphology and behavior. Recombination can influence the configuration of alleles present on a haplotype, and can thus increase or decrease the efficiency of selection. The PRDM9 protein has been shown to be important for determining recombination hotspot locations in humans and other mammals, but of all the mammals studied so far the dog is the only one to have a non-functional PRDM9. We used the genome-wide genotype data described above to characterise the fine scale recombination map in dogs. We find that recombination hotspots exist in dogs despite the absence of PRDM9. Moreover, we show that these hotspots are enriched for GC rich peaks and that these peaks are getting stronger over time. Our results show that the absence of PRDM9 has lead to the stabilisation of the recombination landscape in dogs.

Saskatchewan Highways and Transportation (SDHT) rely on dense-graded hot mix asphalt concrete mixes for construction and rehabilitation of asphalt pavement surfaced highways. As a result of increased commercial truck traffic on the provincial road network, over the last two decades, some of Saskatchewans recently placed dense graded hot mix asphalt concrete (HMAC) pavements have been observed to show a susceptibility to premature permanent deformation in the asphalt mix. One of the aggregate properties thought to have significant influence on mix performance under traffic loading is the shape of the aggregate. Specifically, the physical properties of the fine aggregate (smaller than 5 mm in diameter) are of particular importance in dense graded mixes. Although empirical evidence suggests that there are performance benefits associated with using angular fine aggregate, the relationship of this parameter on mechanistic mix performance and resistance to permanent deformation has not yet been clearly defined.<p>The primary objective of this research was to conduct laboratory analysis to determine the physical, empirical, and mechanistic behaviour sensitivity to the proportion of manufactured and natural fine aggregate in SDHT Type 72 hot mix asphalt concrete. The second objective of this research was to compare the mechanistic behaviour of the Type 72 mixes considered in this research to conventional SDHT Type 70 structural hot mix asphalt concrete.<p>Physical and mechanistic properties of a SDHT Type 72 mix at levels of 20, 40, and 60 percent manufactured fines as a portion of total fines (smaller than 5 mm), and for a SDHT Type 70 mix (which contained 38 percent manufactured fines) were evaluated. Ten repeat samples were compacted for each mix using 75-blow Marshall compaction, and ten samples for each mix were compacted using the Superpave gyratory compaction protocols. Marshall stability and flow testing was conducted on the Marshall-compacted samples. Triaxial frequency sweep testing was conducted on the gyratory-compacted samples using the Rapid Triaxial Tester (RaTT) at 20°C. The testing was conducted at axial loading frequencies of 10 and 0.5 Hz, and at deviatoric stress states of 370, 425, and 500 kPa, respectively. The resulting dynamic modulus, axial and radial microstrains, Poissons ratio, and phase angle were evaluated.<p>The research hypothesis stated that the increased amount of manufactured fines improves mechanistic properties of the Type 72 mix under typical field state conditions, and Type 72 mix with increased manufactured fines can exhibit mechanistic properties equivalent to or exceeding those of a typical type 70 mix. <p>Based on the improved densification properties, increased Marshall stability, increased dynamic modulus, and reduced radial and axial strains, it was demonstrated that increasing manufactured fines content in the SDHT Type 72 mix does improve the mechanistic properties of this dense-graded asphalt mix. It should be noted that there appears to be a minimum level of manufactured fines content that is required to affect mix response to loading, and that this threshold lies somewhere between 40 and 60 percent manufactured fines content for the Type 72 mix tested as part of this research.<p>Further, the Type 72 mix exhibited comparable or improved mechanistic properties relative to the Type 70 mix, which SDHT consider a structural mix. This is illustrated by the Type 72 mix with 60 percent manufactured fines resulting in higher Marshall stability and dynamic modulus, and lower axial microstrains than the Type 70 mix evaluated in this study.<p>It is recommended that other Type 72 and Type 70 mixes are evaluated using similar testing protocols. In addition, field test sections should be used to further verify the research hypothesis investigated here. <p>Economic analysis indicates that substantial savings in life cycle costs of SHDT asphalt concrete surfaced roadways can be realized by engineering well-performing, rut-resistant mixes. The life cycle costs can be reduced annually by approximately $7.4 million, which translates into $102.5 million savings over 18 years, during which the entire pavement network would be resurfaced with well-performing asphalt concrete mixes.<p>Further, enhanced crushing of smaller aggregate top size decreases the amount of rejected material, and increases manufactured fines to coarse aggregate ratio, resulting not only in better engineering properties, but also in the optimized use of the provinces diminishing gravel resources. Pressures on aggregate sources are also reduced by improving life cycle performance of Saskatchewan asphalt concrete pavements. The total potential aggregate savings that can be realized by implementing well-performing Type 72 HMAC mixes amount to 4.3 million metric tonnes of aggregate in the next 42 years. These aggregate savings can help decrease the predicted shortage of aggregate between 2007 and 2049 by approximately 6 percent. The total potential cost savings after 18 years of paving 500 km per year with rut-resistant, well-performing HMAC mixes amount to $112.4 million in present value dollars. The 42 year savings amount to $193.7 million in present day dollars. It is recommended that a more detailed economic analysis be carried out.

Communication networks are vulnerable to natural as well as man-made disasters. The geographical layout of the network influences the impact of these disasters. It is therefore, necessary to identify areas that could be most affected by a disaster and redesign those parts of the network so that the impact of a disaster has least effect on them. In this work, we assume that disasters which have a circular impact on the network. The work presents two new algorithms, namely the WHF-PG algorithm and the WHF-NPG algorithm, designed to solve the problem of finding the locations of disasters that would have the maximum disruptive effect on the communication infrastructure in terms of capacity.

Purpose: There is little agreement on the age at which visual acuity (VA) and contrast sensitivity (CS) become adult-like. The ultimate purpose of this thesis was to determine whether VA and CS are adult-like at the age of 6-8 or 9-12 years by using both objective and subjective methods in the same individuals. The objective method (sweep visually evoked potentials [sVEP]) has many parameters that may affect the measurement of VA or CS and previously these had not been studied systematically, especially in children. Therefore, a second purpose was to study the effects of these parameters on VA and contrast thresholds and to determine the parameters that give the most repeatable measurements and the greatest number of viable readings in children, to be compared to previous data obtained in adults. Methods: The effect of five criteria (C0-C4) for choosing the endpoint for the regression line fitting and three luminance levels (25, 50, and 100 cd/m2) on the sVEP VA and contrast thresholds (at 1 and 8 cpd) was investigated in six 6-8 year old children. Additionally, the effect of these parameters on the number of viable readings obtained from five active electrodes was investigated. C0 was derived from the sVEP software (PowerDiva), C1 used the best fit by eye to determine the range over which the regression line was fitted, C2 used the data point between signal peak and the last data point with an SNR ≥ 1, C3 was similar to C2 but was defined so that the threshold should be within the sweep range, and C4 was similar to C2 except that the SNR should not fall below one at any point within the range used for the regression line fitting. The effects of two electrode placements, three temporal frequencies (6, 7.5, and 10 Hz), sweep direction (low to high and high to low), presence or absence of a fixation target, three stimulus areas (6, 4, and 2° for VA and 15, 10, and 6° for contrast thresholds) and three sweep durations (10, 15, and 20 sec) on VA and contrast thresholds (at 1, 4, or 8 cpd) measured with sVEP were also investigated in six 6-8 year-old children and six adults with normal vision. Additionally, the effect of these parameters on the number of viable readings obtained from five active electrodes was investigated. The sVEP parameters that were found to give the best threshold measurements were employed in a cross sectional study of the development of VA and CS. In this study the objective sVEP technique and two psychophysical techniques were used. The psychophysical techniques were comprised of a two-alternative forced choice (2AFC) staircase for measuring VA and contrast thresholds and signal detection theory (SDT) for measuring contrast threshold. Crowded and uncrowded logMAR VA were also measured with a Bailey-Lovie logMAR chart. The study included three age groups (6-8, 9-12 year olds and adults). The criterion employed by each age group as indicated by the SDT was compared. Results: There was a significant effect of the criterion for choosing the endpoint for the regression line fitting (p < 0.05) on all the measures and a significant effect of luminance (p = 0.036) on contrast threshold at 1 cpd. Criterion C2 (in which the range for the regression line fit was defined to include all the data between the signal peak and the last data point [furthest from the peak] with an SNR ≥ 1) consistently gave more viable readings and better thresholds (i.e. higher VA and lower contrast thresholds) than the other criteria. Also C2 was the best criterion in terms of repeatability in children, and repeatability and validity in adults (Yadav et al., 2009). The luminance of 25 cd/m2 gave higher contrast thresholds than 50 or 100 cd/m2. There was a significant effect of temporal frequency on the number of viable readings for VA (p < 0.0001) and for contrast thresholds (p = 0.0001), with more viable readings at 7.5 Hz than at either 6 or 10 Hz. The adults gave more readings with the fixation target than without it (p = 0.04) for contrast threshold at 1 cpd. The smallest stimulus area used gave rise to fewer viable readings in both adults and children (p = 0.022 for VA and 0.0001 for contrast threshold). The other parameters (electrode placement, sweep direction and sweep duration) did not result in significant differences. There was a significant effect of age on crowded (p = 0.0001) and uncrowded (p < 0.0001) VA. The 6-8 year olds gave poorer VA than the 9-12 year olds or adults for both crowded and uncrowded VA. For the grating VA (sVEP and 2AFC staircase) there was a significant effect of age (p = 0.002). The 6-8 year olds had poorer VA than the 9-12 year olds or adults. For contrast threshold at 1 cpd, a significant effect of age was found for the 2AFC (p = 0.008) and SDT (p = 0.0003). The 6-8 year olds gave poorer contrast thresholds than adults with each procedure. For contrast thresholds at 8 cpd, there was a significant effect of age with the 2AFC staircase (p = 0.036). The 6-8 year olds gave poorer contrast thresholds than the 9-12 year olds. For SDT, there was a significant effect of age on criterion (p < 0.05), with adults being more likely to say “no” in the yes-no SDT procedure than both the 6-8 year olds and the 9-12 year olds for contrast threshold at 1 cpd. Adults were also more likely to say “no” than the 9-12 year olds for contrast thresholds at 8 cpd. Conclusions: This thesis has shown that VA and CS are not adult-like until the age of 9-12 years by these measures and that children do show differences in criterion compared to adults in psychophysical testing. This difference in criterion indicates the use of SDT or force-choice procedures to avoid this problem in any psychophysical developmental study. It has also shown that criterion for choosing the endpoint for the regression line fitting in the sVEP technique has the greatest effect on VA and contrast thresholds measurements and viable readings, while the other sVEP parameters have little effect on the thresholds.

Saskatchewan Highways and Transportation (SDHT) rely on dense-graded hot mix asphalt concrete mixes for construction and rehabilitation of asphalt pavement surfaced highways. As a result of increased commercial truck traffic on the provincial road network, over the last two decades, some of Saskatchewans recently placed dense graded hot mix asphalt concrete (HMAC) pavements have been observed to show a susceptibility to premature permanent deformation in the asphalt mix. One of the aggregate properties thought to have significant influence on mix performance under traffic loading is the shape of the aggregate. Specifically, the physical properties of the fine aggregate (smaller than 5 mm in diameter) are of particular importance in dense graded mixes. Although empirical evidence suggests that there are performance benefits associated with using angular fine aggregate, the relationship of this parameter on mechanistic mix performance and resistance to permanent deformation has not yet been clearly defined.<p>The primary objective of this research was to conduct laboratory analysis to determine the physical, empirical, and mechanistic behaviour sensitivity to the proportion of manufactured and natural fine aggregate in SDHT Type 72 hot mix asphalt concrete. The second objective of this research was to compare the mechanistic behaviour of the Type 72 mixes considered in this research to conventional SDHT Type 70 structural hot mix asphalt concrete.<p>Physical and mechanistic properties of a SDHT Type 72 mix at levels of 20, 40, and 60 percent manufactured fines as a portion of total fines (smaller than 5 mm), and for a SDHT Type 70 mix (which contained 38 percent manufactured fines) were evaluated. Ten repeat samples were compacted for each mix using 75-blow Marshall compaction, and ten samples for each mix were compacted using the Superpave gyratory compaction protocols. Marshall stability and flow testing was conducted on the Marshall-compacted samples. Triaxial frequency sweep testing was conducted on the gyratory-compacted samples using the Rapid Triaxial Tester (RaTT) at 20°C. The testing was conducted at axial loading frequencies of 10 and 0.5 Hz, and at deviatoric stress states of 370, 425, and 500 kPa, respectively. The resulting dynamic modulus, axial and radial microstrains, Poissons ratio, and phase angle were evaluated.<p>The research hypothesis stated that the increased amount of manufactured fines improves mechanistic properties of the Type 72 mix under typical field state conditions, and Type 72 mix with increased manufactured fines can exhibit mechanistic properties equivalent to or exceeding those of a typical type 70 mix. <p>Based on the improved densification properties, increased Marshall stability, increased dynamic modulus, and reduced radial and axial strains, it was demonstrated that increasing manufactured fines content in the SDHT Type 72 mix does improve the mechanistic properties of this dense-graded asphalt mix. It should be noted that there appears to be a minimum level of manufactured fines content that is required to affect mix response to loading, and that this threshold lies somewhere between 40 and 60 percent manufactured fines content for the Type 72 mix tested as part of this research.<p>Further, the Type 72 mix exhibited comparable or improved mechanistic properties relative to the Type 70 mix, which SDHT consider a structural mix. This is illustrated by the Type 72 mix with 60 percent manufactured fines resulting in higher Marshall stability and dynamic modulus, and lower axial microstrains than the Type 70 mix evaluated in this study.<p>It is recommended that other Type 72 and Type 70 mixes are evaluated using similar testing protocols. In addition, field test sections should be used to further verify the research hypothesis investigated here. <p>Economic analysis indicates that substantial savings in life cycle costs of SHDT asphalt concrete surfaced roadways can be realized by engineering well-performing, rut-resistant mixes. The life cycle costs can be reduced annually by approximately $7.4 million, which translates into $102.5 million savings over 18 years, during which the entire pavement network would be resurfaced with well-performing asphalt concrete mixes.<p>Further, enhanced crushing of smaller aggregate top size decreases the amount of rejected material, and increases manufactured fines to coarse aggregate ratio, resulting not only in better engineering properties, but also in the optimized use of the provinces diminishing gravel resources. Pressures on aggregate sources are also reduced by improving life cycle performance of Saskatchewan asphalt concrete pavements. The total potential aggregate savings that can be realized by implementing well-performing Type 72 HMAC mixes amount to 4.3 million metric tonnes of aggregate in the next 42 years. These aggregate savings can help decrease the predicted shortage of aggregate between 2007 and 2049 by approximately 6 percent. The total potential cost savings after 18 years of paving 500 km per year with rut-resistant, well-performing HMAC mixes amount to $112.4 million in present value dollars. The 42 year savings amount to $193.7 million in present day dollars. It is recommended that a more detailed economic analysis be carried out.

Pattern geometry plays a major role in determining oil recovery during waterflooding and enhanced oil recovery operations. Although simulation is an important tool for design and evaluation, the first step often involves rough calculations based upon areal sweep efficiencies of displacements in homogeneous, two-dimensional, scaled, physical models. These results are available as a function of the displacement pattern and the mobility ratio M. In this research I studied the effect of mobility ratios on five-spot and staggered waterflood patterns behavior for areal (2D) displacement in a reservoir that is homogeneous and isotropic containing no initial gas saturation. Simulation was performed using Eclipse 100 simulator. Simulation results are presented as graphs of areal sweep efficiency at breakthrough versus Craig mobility ratio for various staggered line drive aspect ratios. The main results of the study are presented in the form of a graph of areal sweep efficiency at breakthrough as a function of staggered line drive aspect ratio. This should enable engineers to utilize the results in a convenient manner.

Fractures make both opportunities and problems for exploration and production from hydrocarbon reservoirs. It is always difficult to predict how to optimally produce a fractured reservoir due to the complexity and heterogeneity of fluid flow paths. The following behavior is seen in fractured reservoirs: early water breakthroughs, reduced tertiary recovery efficiency due to channeling of injected gas or fluids, dynamic calculations of recoverable hydrocarbons that are much less than static mass balance and dramatic production changes due to changes in reservoir pressure as fractures close down as conduits. These problems often lead to reduced ultimate recoveries or higher production costs. Polymer gels, in particular in-situ gels that can be placed deep into the reservoir, have been widely used for improved conformance control. In this dissertation, we aim to block the high-permeability zones, fractures in particular, with the microgels to increase the sweep efficiency by diverting the waterflood water to the low permeability zones that still contain unswept oil. vii Polyacrylic acid microgels can swell a thousand fold as the pH of the surrounding solution changes, with an accompanying large increase in viscosity. This pH trigger is simpler than chemical cross-linking and thus offers operational advantages. The ability of pH-sensitive polymers to block high permeability fractures is studied by performing several coreflood and batch experiments. The effect of different rock and salt minerals, polymer concentration, polymer salinity, and temperature on polymer performance is studied in this dissertation. Polymer microgels show excellent consistency in the presence of various salt minerals and in contact with different rock minerals. The placement of microgels into the fractures lowered the overall core permeability in all cases. In addition, polymer microgels were stable after being in reservoir for a month with conditions at 58°C. Consequently, using pH-triggered polymers for conformance control and reducing the permeability of high permeability areas in fractured reservoirs merit further investigations. These polymers are inexpensive and are easy to prepare. The polymer concentration, salinity and shut-in time could be set according to the desired PRF value, injectivity, propagation distance and reservoir mineralogy. / text