• Review and experimental studies to evaluate the impact of salinity and wettability on oil recovery efficiency

      Agbalaka, Chinedu C. (2006-05)
      Oil recovery efficiency is influenced by a myriad of interacting variables such as pore geometry, wettability, rock mineralogy, brine salinity, oil composition, etc. Reservoir wettability is known to have very significant influence on pore scale displacement and hence is a strong determinant of the final residual oil saturation. Recent studies have indicated the improved oil recovery potential of low salinity brine injection. Though the reason for this reported increase is still unclear, it is speculated that it may be due to wettability changes. In this work, coreflood studies were carried out to determine the recovery benefits of low salinity waterflood over high salinity waterflood and the role of wettability in any observed recovery benefit. Two sets of coreflood experiments were conducted; the first set examined the EOR potential of low salinity floods in tertiary oil recovery processes while the second set examined the secondary oil recovery potential of low salinity floods. Changes in residual oil saturation with variation in wettability and brine salinity were monitored. All the coreflood tests consistently showed an increase in produced oil and water-wetness with decrease in brine salinity and increase in brine temperature.
    • A review of oil spill history and management on the North Slope of Alaska

      Davila, Amanda (2013-12)
      Alaska has an abundance of natural resources including oil, natural gas and coal. It is critical to minimize the occurrence of oil spills to ensure protection of Alaska's people and the environment. The objective of this project is twofold. One is to provide a quantification of the number of spills on the North Slope (NS) as well as the number of contaminated sites that are generated, describe the regulatory requirements for the Arctic zone, and discuss cleanup methods. Second is to describe the ADEC regulations as they pertain to terrestrial oil spills. The region of study begins north of Alyeska's Pump Station 4 at the Dalton Highway milepost 270, TAPS 144, north to the Beaufort Sea, encompassing all oil related operations. This review excludes spills at villages (not related to oil field operations), and releases to the atmosphere (e.g., halon, propane). Additionally, spills at formally used defense sites (FUDS) and long range radar sites are also excluded from this study. Spills that result in long term monitoring and cleanup are managed as contaminated sites. The data reveals that the majority of contaminated sites have been cleaned up with no institutional controls in place. The number of spills on the North Slope is consistent with activity. The time during the peak oil is when there are a higher number of spills. Over time, as the oil production and activity decline, so do the number of spills with a few exceptions. The decline in oil production has limited activity and growth on the NS.
    • Review of Power Sources for Alaska DOT&PF Road Weather Information Systems (RWIS): Phase I

      Wies, Richard (2014-08)
      This report documents the findings related to a review of power sources for six off-grid Road Weather Information Systems (RWIS) in Alaska. Various power sources were reviewed as a means of reliably operating the off-grid RWIS sites throughout the year. Based on information collected on current power sources and equipment used at the off-grid RWIS sites, and visits to off-grid installations in Alaska, some viable methods of reliable operation were discovered. Power sources included in the study were solar photovoltaics (PV), small wind turbines, fuel cells, and thermoelectric generators, all charging a battery bank which powers the weather sensors, cameras, and communication equipment. The results showed that while solar PV provides enough standalone power to keep the sites operational from early spring to late fall with wind supplementing this somewhat during the transition seasons, a fossil fuel based source is necessary to maintain operation through the winter. These findings suggest that a combination of power sources is required for reliable RWIS operation throughout the year and is dependent on the location of the site.
    • Risk Evaluation for Permafrost-Related Threats:Methods of Risk Estimation and Sources of Information

      Kanevskiy, Mikhail; Connor, Billy; Schnabel, Bill; Shur, Yuri; Bjella, Kevin; Trochim, Erin; Dean, Kelsey; Ellison, Ariel (2019-05)
      In our evaluation of permafrost-related threats that affect Alaska communities, we have focused on threats associated with permafrost degradation and thawing ground ice, which can result in significant thaw settlement and cause unacceptable damage to engineered structures. Our evaluation system for permafrost-related threats includes risks of general permafrost degradation and thaw settlement (general and differential). We have evaluated permafrost-related threats for 187 Alaska villages based on available information including scientific publications, maps, satellite imagery and aerial photographs, geotechnical reports, personal communication, community plans and reports, and other sources. Evaluation was based on five criteria: permafrost (PF) occurrence; PF temperature; thaw susceptibility of frozen soils (expected thaw settlement in case of permafrost degradation); massive ice occurrence; and existing PF-related problems. For each of these categories, four risk levels (ranks) were considered. The total (cumulative) risk level was based on the rating score (sum of individual ranks for all five categories). Based on the rating score, each village was assigned one of four risk levels: 0 – no permafrost; 5–8 – low risk level; 9–11 – medium risk level; 12–15 – high risk level. A vulnerability score was developed for each community allowing the identification of communities with the highest risk of damage due to thawing permafrost. Most of communities with the high-risk level (22 villages of 34) are underlain by continuous permafrost, while the low risk level is typical mainly of communities underlain by predominantly unfrozen soils/bedrocks (33 villages of 46), and no high risk levels were detected for this group of villages. Medium risk level is typical mainly of communities underlain by discontinuous and sporadic permafrost (35 villages of 47); some villages of this group are characterized by high and low risk levels (12 and 9, correspondingly). Occurrence of massive-ice bodies (mostly ice wedges) is typical exclusively of communities underlain by continuous and discontinuous permafrost (23 and 20 villages, correspondingly). We presume that at least 20 communities may have extremely ice-rich yedoma deposits with large ice wedges either within villages or in their vicinity. Permafrost conditions in Alaskan communities are very diverse, and in many cases they are extremely variable even within the same community. Detailed studies are required for more precise evaluation of potential permafrost-related threats associated with permafrost degradation and/or thawing of ground ice.
    • Robust control of geared and direct-drive robotic manipulators under parameter and model uncertainties

      Suravaram, Praveen Reddy; Bogosyan, Seta; Sonwalkar, Vikas; Aspnes, John (2005-05)
      The major contribution of this thesis is the design and evaluation of a chattering-free sliding mode controller (SMC), which is a novel application for 2 degree-of-freedom (DOF) planar robot arms exposed to load variations. The performance of the SMC is evaluated in comparison to a proportional-derivative-plus (PD+) controller, as an example of nonlinear model-based controllers, as well as classical linear controllers, such as proportional-derivative (PD) and proportional-integral-derivative (PID). The performance of all four methods has been tested via realistic and detailed simulation models developed for both geared and direct-drive type 2-DOF planar robot arms. The model used in simulations reflects the dynamics of the arm, as well as the actuator dynamics and pulse width modulation (PWM) switching of the power converters. Simulations are performed under unknown load variations for both step and sinusoidal type reference joint trajectories. The results demonstrate that the chattering-free SMC provides increased accuracy and robustness than that of the other controllers and requires no prior knowledge of the system dynamic model and the load variation that the end-effector is subjected to. The results obtained could be extended to the control of a variety of geared and direct-drive type robotic configurations.
    • Role Of Antennas And The Propagation Channel On The Performance Of An Ultra Wide Band (Uwb) Communication System

      Venkatasubramanian, Arun; Sonwalkar, Vikas (2007)
      The objectives of this dissertation are to experimentally and numerically quantify the effect of antennas and the propagation channel on the performance of an Ultra Wide Band (UWB) receiver. This work has led to the following new results: (1) the variation in the time duration of the impulse response of the oval dipole in the vertical plane is within 5% up to an angle theta = 60° off the broadside direction (theta = 90°); at larger angles a factor of six elongation in the time duration of the impulse response along the antenna axis (theta = 0°) is observed, (2) for an axial ratio of 0.5, the oval dipole has a Voltage Standing Wave Ratio (VSWR) of 2:1 (~11% reflection coefficient) in a 3.1 GHz bandwidth with a lower cut off frequency of 2.8 GHz; for an axial ratio of 2.0 this scales to 0.5 GHz bandwidth with a lower cut off frequency of 1.75 GHz, (3) a new theoretical model has been developed for UWB pulse propagation over the ground which takes into account the geometrical properties of the propagation channel (such as the heights of the transmitter (h1) and the receiver (h2) over the ground) and the nature of the radiated UWB pulse (such as pulse duration (taup) and cycle time (tauc)), (4) an improvement in bit error rate by up to a factor of 100 can be achieved for a matched filter receiver by careful orientation of the transmitting and the receiving oval dipole antennas used in the measurements presented in this dissertation.
    • The role of tundra vegetation in the Arctic water cycle

      Clark, Jason A.; Tape, Ken; Schnabel, William; Euskirchen, Eugénie; Ruess, Roger (2019-12)
      Vegetation plays many roles in Arctic ecosystems, and the role of vegetation in linking the terrestrial system to the atmosphere through evapotranspiration is likely important. Through the acquisition and use of water, vegetation cycles water back to the atmosphere and modifies the local environment. Evapotranspiration is the collective term used to describe the transfer of water from vascular plants (transpiration) and non-vascular plants and surfaces (evaporation) to the atmosphere. Evapotranspiration is known to return large portions of the annual precipitation back to the atmosphere, and it is thus a major component of the terrestrial Arctic hydrologic budget. However, the relative contributions of dominant Arctic vegetation types to total evapotranspiration is unknown. This dissertation addresses the role of vegetation in the tundra water cycle in three chapters: (1) woody shrub stem water content and storage, (2) woody shrub transpiration, and (3) partitioning ecosystem evapotranspiration into major vegetation components. In Chapter 1 I present a method to continuously monitor Arctic shrub water content. The water content of three species (Salix alaxensis, Salix pulchra, Betula nana) was measured over two years to quantify seasonal patterns of stem water content. I found that spring uptake of snowmelt water and stem water storage was minimal relative to the precipitation and evapotranspiration water fluxes. In Chapter 2, I focused on water fluxes by measuring shrub transpiration at two contrasting sites in the arctic tundra of northern Alaska to provide a fundamental understanding of water and energy fluxes. The two sites contrasted moist acidic shrub tundra with a riparian tall shrub community having greater shrub density and biomass. The much greater total shrub transpiration at the riparian site reflected the 12-fold difference in leaf area between the sites. I developed a statistical model using vapor pressure deficit, net radiation, and leaf area, which explained >80% of the variation in hourly shrub transpiration. Transpiration was approximately 10% of summer evapotranspiration in the tundra shrub community and a possible majority of summer evapotranspiration in the riparian shrub community. At the tundra shrub site, the other plant species in that watershed apparently accounted for a much larger proportion of evapotranspiration than the measured shrubs. In Chapter 3, I therefore measured partitioned evapotranspiration from dominant vegetation types in a small Arctic watershed. I used weighing micro-lysimeters to isolate evapotranspiration contributions from moss, sedge tussocks, and mixed vascular plant assemblages. I found that mosses and sedge tussocks are the major constituents of overall evapotranspiration, with the mixed vascular plants making up a minor component. The potential shrub transpiration contribution to overall evapotranspiration covers a huge range and depends on leaf area. Predicted increases in shrub abundance and biomass due to climate change are likely to alter components of the Arctic hydrologic budget. The thermal and hydraulic properties of the moss and organic layer regulate energy fluxes, permafrost stability, and future hydrologic function in the Arctic tundra. Shifts in the composition and cover of mosses and vascular plants will not only alter tundra evapotranspiration dynamics, but will also affect the significant role that mosses, their thick organic layers, and vascular plants play in the thermodynamics of Arctic soils and in the resilience of permafrost.
    • Rural Alaska Electric Power Quality

      Aspnes, J.D. (1984-03)
      Poor quality electric power has traditionally been blamed for electrical and electronic equipment malfunctions and failures in rural Alaskan communities. This report presents results of a recently completed project in which power system disturbance analyzers provide the first comprehensive power quality data from Alaskan villages. Power systems of four widely separated communities were studied for a total of 1,010 days. These results are important because of the trend in rural Alaska toward more sophisticated equipment that is sensitive to power system disturbances. These data represent a first step in developing appropriate countermeasures to protect electrical systems connected to isolated rural 60 Hz power generator facilities
    • Rural Electric Power Quality Analysis Data Base Development

      Aspnes, J.; Merritt, R.; Spell, B.D.; Woodruff, K.; Alden, D.; Mulligan, G. (1987-03)
      The actual cost of poor quality electric power is difficult to accurately determine. Such cost information is important in determining the extent to which power quality enhancement techniques should be applied. This report presents data compiled to help determine the quantity and type of electrical and electronic equipment at risk in rural Alaska and the repair frequency of this equipment. Cost attributable to poor electric power quality are identified. Methods of electric power quality improvement and their relative costs are presented.
    • Rural Facility Electric Power Quality Analysis

      Aspnes, J.D.; Zhao, Y. Q.; Spell, B.D.; Merrit, R.P. (1991-03)
      This report gives results of a recently completed data collection and analysis project investigating electric power quality of two isolated utility systems in Alaska. This is the second phase of a similar effort reported in 1984 which provided the first comprehensive power quality data from four small Alaskan communities. In this report, second generation instrumentation is described and comprehensive data and data analyses are presented. These data are important because of the increased use throughout Alaska of electrical and electronic equipment that may be damage by power system disturbances.
    • Rural Facility Electric Power Quality Enhancement

      Wilson, M.; Aspnes, J.D.; Merritt, R.P.; Spell, B.D. (1991-05)
      Electric power disturbances are known to be more prevalent in small, isolated power systems than in larger interconnected grids which service most of the United States. This fact has given rise to a growing concern about the relative merits of different types of power conditioning equipment and their effectiveness in protecting sensitive electronics and essential loads in rural Alaska. A study has been conducted which compares isolation transformers, voltage regulators, power conditioners, uninterruptible power supplies and indoor computer surge suppressors in their ability to suppress the various disturbances which have been measured in several Alaskan communities. These include voltage sags and surges, impulses, blackouts, frequency variations and long-term voltage abnormalities. In addition, the devices were also subjected to fast, high-magnitude impulses such as might be expected in the event of a lightning strike to or near utility distribution equipment. The solutions for power line problems will vary for different load applications and for different rural electrical environments. The information presented in this report should prove to be valuable in making the analysis.
    • Safety Data Management: Gathering and Using the Data

      Perkins, Robert A; Bennett, F. Lawrence (2016-07-14)
      How are roadway crash data acquired, stored, and utilized in engineering and management decisions regarding highway projects? This research answers that question by interviewing the engineers and professionals involved with that safety data management from six states and asking – How are safety (crash) data acquired and used in their states. Since most safety projects are funded by the federal FHWA, through the HSIP, the general flow of the safety data is similar in the states interviewed. But there are many differences in details, especially the computer hardware and software. The methods of data movement between the responder and the DOT often involve an intermediate agency, often the DMV – this varies between the states. Likewise, the program to extract these data for the DOT varies. Another pronounced difference is the transfer of HSIP funding to local agencies. Also pronounced is the use of historical crash data in the SPFs. The older method of only looking at the crash data from the location in question is not uncommon, while the more modern method of using data from similar locations via an EB analysis is becoming more common and is the currently recommended method. Most analysis software is geared to the EB analysis. Historical crash data, before and after countermeasures are installed, may be used to evaluate SPF and CMF for particular states and localities, but there are practical problems with this application of crash data, due to the time required to acquire adequate data for comparisons.
    • Sagavanirktok River Particle Size Distributions

      Tape, Ken; Clark, Jason; Toniolo, Horacio (2017-10)
    • Sagavanirktok River Spring Breakup Observations 2015

      Toniolo, H.; Youcha, E.K.; Gieck, R.E.; Tschetter, T.; Engram, M.; Keech, J. (2015-12)
      Alaska’s economy is strongly tied to oil production, with most of the petroleum coming from the Prudhoe Bay oil fields. Deadhorse, the furthest north oil town on the Alaska North Slope, provides support to the oil industry. The Dalton Highway is the only road that connects Deadhorse with other cities in Interior Alaska. The road is heavily used to move supplies to and from the oil fields. In late March and early April 2015, the Dalton Highway near Deadhorse was affected by ice and winter overflow from the Sagavanirktok River, which caused the road’s closure two times, for a total of eleven days (four and seven days, respectively). In mid-May, the Sagavanirktok River at several reaches flooded the Dalton from approximately milepost (MP) 394 to 414 (Deadhorse). The magnitude of this event, the first recorded since the road was built in 1976, was such that the Dalton was closed for nearly three weeks. During that time, a water station and several pressure transducers were installed to track water level changes on the river. Discharge measurements were performed, and water samples were collected to estimate suspended sediment concentration. Water levels changed from approximately 1 m near MP414 to around 3 m at the East Bank station, located on the river’s east bank (about MP392). Discharge measurements ranged from nearly 400 to 1560 m3/s, with the maximum measurement roughly coinciding with the peak. Representative sediment sizes (D50) ranged from 10 to 14 microns. Suspended sediment concentrations ranged from a few mg/L (clear water in early flooding stages) to approximately 4500 mg/L. An analysis of cumulative runoff for two contiguous watersheds—the Putuligayuk and Kuparuk—indicates that 2014 was a record-breaking year in both watersheds. Additionally, an unseasonable spell of warm air temperatures was recorded during mid-February to early March. While specific conditions responsible for this unprecedented flood are difficult to pinpoint, runoff and the warm spell certainly contributed to the flood event.
    • Sagavanirktok River Spring Breakup Observations 2016

      Toniolo, H.; Tape, K.D.; Tschetter, T.; Homan, J.W.; Youcha, E.K.; Vas, D.; Gieck, R.E.; Keech, J.; Upton, G. (2016-12)
      In 2015, spring breakup on the Sagavanirktok River near Deadhorse was characterized by high flows that destroyed extensive sections of the Dalton Highway, closing the road for nearly 3 weeks. This unprecedented flood also damaged infrastructure that supports the trans-Alaska pipeline, though the pipeline itself was not damaged. The Alaska Department of Transportation and Public Facilities (ADOT&PF) and the Alyeska Pipeline Service Company made emergency repairs to their respective infrastructure. In December 2015, aufeis accumulation was observed by ADOT&PF personnel. In January 2016, a research team with the University of Alaska Fairbanks began monitoring and researching the aufeis and local hydroclimatology. Project objectives included determining ice elevations, identifying possible water sources, establishing surface meteorological conditions prior to breakup, measuring hydrosedimentological conditions (discharge, water level, and suspended sediment concentration) during breakup, and reviewing historical imagery of the aufeis feature. Ice surface elevations were surveyed with Global Positioning System (GPS) techniques in late February and again in mid-April, and measureable volume changes were calculated. However, river ice thickness obtained from boreholes near Milepost 394 (MP394) in late February and mid-April revealed no significant changes. It appears that flood mitigation efforts by ADOT&PF in the area contributed to limited vertical growth in ice at the boreholes. End-of-winter snow surveys throughout the watershed indicate normal or below normal snow water equivalents (SWE 10 cm). An imagery analysis of the lower Sagavanirktok aufeis from late winter for the past 17 years shows the presence of ice historically at the MP393–MP396 area. Water levels and discharge were relatively low in 2016 compared with 2015. The mild breakup in 2016 seems to have been due to temperatures dropping below freezing after the flow began. Spring 2015 was characterized by warm temperatures throughout the basin during breakup, which produced the high flows that destroyed sections of the Dalton Highway. A comparison of water levels at the East Bank Station during 2015 and 2016 indicates that the 2015 maximum water level was approximately 1 m above the 2016 maximum water level. ii Maximum measured discharge in 2016 was approximately half of that measured in 2015 in the lower Sagavanirktok River. Representative suspended sediment sizes (D50) ranged from 20 to 50 microns (medium to coarse silt). An objective of this study was to determine the composition and possible sources of water in the aufeis at the lower Sagavanirktok River. During the winter months and prior to breakup in 2016, overflow water was collected, primarily near the location of the aufeis, but also at upriver locations. Simultaneously possible contributing water sources were sampled between January and July 2016, including snow, glacial meltwater, and river water. Geochemical analyses were performed on all samples. It was found that the overflow water which forms the lower Sagavanirktok aufeis is most similar (R2 = 0.997) to the water that forms the aufeis at the Sagavanirktok River headwaters (Ivishak River), thought to be fed by relatively consistent groundwater sources.
    • Saline Conversion and Ice Structures from Artificially Grown Sea Ice

      Peyton, H. R.; Johnson, P. R.; Behlke, C. E. (University of Alaska, Arctic Environmental Engineering Laboratory and University of Alaska, Institute of Water Resources, 1967-09)
      The environment of cold regions is generally viewed as inhospitable, primarily due to application of ideal processes and techniques suitable to temperate zones. The work herein is a step toward solving two environmental problems. The first involves the supply of inexpensive, potable water in Arctic regions, the lack of which is a severe detriment to development. Although water does exist in the Arctic, it is neither available in potable form during many months of the year nor does it occur in sufficient quantity near the point of use. Principally, this lack is caused by the aridness of the Arctic and the shallowness of fresh water sources which, for all practical purposes, do not exist but freeze completely each winter season. The remaining liquid water source is the sea. Arctic problems are then similar to other arid regions where the conversion of sea water to potable water or the transmission of potable water to desired locations is necessary. Cold temperatures generally preclude transmission except over very short distances. Desalination by freezing sea water is a much reported process and has been included among the desalination processes under study worldwide. The advantage of this method in the Arctic is the cold winter-time temperature for freezing and the existence of adequate solar energy in the summer for melting self purified ice. Power requirements are greatly reduced using these natural phenomena. The second aspect of this study concerns the use of artificially grown sea ice as a structural material, thinking primarily in terms of coastal facilities such as docks, jetties, islands, platforms, etc. At sufficiently high latitudes, the summer ablation can be controlled to the point where major structures can be maintained intact during the summer. The unit cost of material is quite low because of low energy requirements. The results of this study show that each of these sea water uses have considerable promise. Desalination to potable level was accomplished. Ice growth rates were obtained which indicate that ice structures of substantial size can be built.
    • Scaling laws in cold heavy oil production with sand reservoirs

      Robertson, Keith W. III; Awoleke, Obadare; Peterson, Rorik; Ahmadi, Mohabbat; Liu, Jenny (2018-08)
      This thesis presents a rigorous step by step procedure for deriving the minimum set of scaling laws for Cold Heavy Oil Production with Sand (CHOPS) reservoirs based on a given set of physical equations using inspectional analysis. The resulting dimensionless equations are then simulated in COMSOL Mutiphysics to validate the dimensionless groups and determine which groups are more significant by performing a sensitivity analysis using a factorial design. The work starts simple by demonstrating how the above process is done for 1D single-phase flow and then slowly ramps up the complexity to account for foamy oil and then finally for wormholes by using a sand failure criterion. The end result is three dimensionless partial differential equations to be solved simultaneously using a finite element simulator. The significance of these groups is that they can be used to extrapolate between a small scale model and a large scale prototype.
    • Scintillation at K-band and Ka-band frequencies

      Kim, Táe-hong (2000-05)
      The need for higher bandwidth and smaller antenna size for satellite communications led NASA to fund the Advanced Communications Technology Satellite (ACTS) and propagation research for K-band and Ka-band frequencies. From December 1993 to December 1998, seven sites in North America have collected and processed power measurements at 20.2 and 27.5 gigahertz from ACTS, a geostationary statellite located at 100 ̊West longitude. The thesis compares scintillation measurements to eight scintillation prediction models, proposes a cumulative distribution model to help predict the percentage of time scintillation exceeds a given threshold, examines the effects of frequency on scintillation magnitudes, and proposes a climate model based on moisture content to help predict scintillation magnitudes. The study concludes that the scintillation prediction models are dependent on the climate, the frequency dependence is a function of climate, and the moisture content in the atmosphere dictates the percentage of time large scintillation occurs.
    • Seasonal Effects Of Frozen Soil On The Stiffness Of Bridge Piles

      Horazdovsky, Jacob E.; Hulsey, J. Leroy (2010)
      In the northern regions, the upper layer of soil is frozen throughout winter months. Soil stiffness can be expected to increase several orders of magnitude as it changes from thawed to frozen. Thus, pile foundation systems embedded in frozen soils are considerably stiffer during winter months when subjected to lateral loads. This thesis explores and quantifies stiffness change for 16 inch diameter steel jacketed, reinforced concrete pilings in seasonally frozen silt. Two test piles were driven 20 feet into silty soil at a site approximately 1.5 miles from Fairbanks, Alaska. Three quasi-static lateral load cyclic tests were conducted on the piles throughout the year; one in September when the soil was thawed, the other two in January and March with frost depths of 4.5 and 7.5 feet respectively. Soil temperatures ranged from thawed to -18 degrees C. The shear demand on the piles increased by over 400 percent. Depth to fixity changed from approximately 6 pile diameters (thawed) to less then 0.75 pile diameters (frozen).
    • Seasonally Frozen Soil Effects on the Seismic Performance of Highway Bridges

      Hulsey, J. Leroy; Horzdovsky, Jacob E.; Davis, Duane; Yang, Zhaohui Joey; Li, Qiang (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2011)