Now showing items 858-877 of 918

• #### Toward computer generated folk music using recurrent neural networks

In this paper, we compare the effectiveness of two different types of Recurrent Neural Networks, fully connected and Long Short Term Memory, for modeling music compositions. We compare both the categorical accuracies of these models as well as the quality of generated compositions, and find that the model based on Long Short Term Memory is more effective in both cases. We find that the fully connected model is not capable of generating non repeating note sequences longer than a few measures, and that the Long Short Term Memory model can do significantly better in some cases.
• #### A Town Meeting on Energy : Prepared for Interior Alaskans

On March 26, 1977, an all-day Town Meeting on Energy was held at the Hutchison Career Development Center on Geist Road in Fairbanks, Alaska. This event was sponsored by the Alaska Humanities Forum in cooperation with the Fairbanks North Star Borough School District; the Institute of Water Resources at the University of Alaska, Fairbanks; and the Fairbanks Town and Village Association. This publication reports the activities during and the information resulting from this town meeting.
• #### Trace element copper distribution and areal geology in a portion of the Clearwater Mountains, Alaska

The study concerns that portion of the Clearwater Mountains defined by north latitudes 63' 03' and 63' 08' and west longitudes 147' 09' and 147' 30'. Outcrop within the area consists predominantly of a sequence of intercalated andesitic and basaltic flows. Sedimentary rocks are present but comprise a very small percentage of the total section. Dikes and a small pluton are also present. The prevailing attitude of the volcanic and sedimentary rocks is east-northeast with a consistent north dip. A Triassic age is accepted for the volcanic and sedimentary rocks. Areal and local sampling indicates that all rock types are abnormally high in trace copper content, and average background is 1000 ppm. Copper distribution suggests a syngenetic origin. Frequent small copper deposits crop out along the north side of the area. The deposits are epigcnctic and are structurally controlled. The origin of these deposits may have potential exploration significance.
• #### Transport of fecal bacteria in a rural Alaskan community

People living without piped water and sewer can be at increased risk for fecal-oral diseases. One Alaskan village that relies on hauled water and honeybuckets was studied to determine the pathways of fecal contamination of drinking water and the human environment so that barriers can be established to protect health. Samples were tested for the fecal indicators Escherichia coli and Enterococcus. Several samples were also tested for the pathogens Giardia lamblia and Cryptosporidium parvum. All terrain vehicle (ATV) use and foot traffic transported bacteria within the village and into the home. Surface water flow transported bacteria within the community during spring thaw, but flow from the dump did not appear to contribute to contamination in town. Within the home, viable fecal bacteria were found on waterdippers, kitchen counters and floors, and in washbasin water. Giardia was found at the dump, but not in water from the river adjacent the community. Exposure to fecal contamination could be reduced by cleaning up after dogs, careful disposal of honey bucket bags and gray water, and by protecting stored drinking water.
• #### Transportation economics of coal resources of northern slope coal fields, Alaska

This paper describes the Northern coal fields, the environment in which they are situated, and various routes and systems for transporting metallurgical qua1ity coal from these deposits to a potential market in Japan. Each transportation mode is discussed with respect to northern Alaska conditions. Capitol and operating costs were developed for each system. If the coal must support the entire transportation system cost, the transportation of coal from the North Slope of Alaska to Japan appears to be economically feasible only from easily mined areas which are close to an ocean shipping port. In the case of transportation cost sharing by other users, or by government subsidization, the prospects of northern coal exploitation would be enhanced. The final feasibility of developing any of this coal deposit cannot be determined until the mining costs and the factors which influence these costs are known.
• #### Transportation Life Cycle Assessment Synthesis Phase II

Center for Environmentally Sustainable Transportation in Cold Climates, 2018-04-24
The Transportation Life Cycle Assessment (LCA) Synthesis includes an LCA Learning Module Series, case studies, and analytics on the use of the modules. The module series is a set of narrated slideshows on topics related to environmental LCA. Phase I produced 27 modules, and Phase II added 10 more. The modules are available for download on the Lamar CEE website https://www.lamar.edu/engineering/civil/faculty/haselbach/lca-modules.html and on the CESTiCC website http://cem.uaf.edu/cesticc/publications/lca.aspx. The modules are around 20 minutes long and may be used for various purposes such as for class lectures or part thereof, and for background learning in research or application. The modules are organized into four topical areas, each containing overview and detailed modules. The A and α groups cover the international standards that define environmental LCA. The B and β groups summarize some of the typical environmental impact categories in LCA. The G and γ groups include software tools for LCA. The T and τ groups focus on the growing field of transportation with respect to LCA, a complex area of importance. The analytics section provides data on downloads of the modules from the websites and summary survey results from course implementation.
• #### Transportation Life Cycle Assessment Synthesis: Life Cycle Assessment Learning Module Series

The Life Cycle Assessment Learning Module Series is a set of narrated, self-advancing slideshows on various topics related to environmental life cycle assessment (LCA). This research project produced the first 27 of such modules, which are freely available for download on the CESTiCC website http://cem.uaf.edu/cesticc/publications/lca.aspx. Each module is roughly 15- 20 minutes in length and is intended for various uses such as course components, as the main lecture material in a dedicated LCA course, or for independent learning in support of research projects. The series is organized into four overall topical areas, each of which contain a group of overview modules and a group of detailed modules. The A and α groups cover the international standards that define LCA. The B and β groups focus on environmental impact categories. The G and γ groups identify software tools for LCA and provide some tutorials for their use. The T and τ groups introduce topics of interest in the field of transportation LCA. This includes overviews of how LCA is frequently applied in that sector, literature reviews, specific considerations, and software tutorials. Future modules in this category will feature methodological developments and case studies specific to the transportation sector.
• #### Treatment of Low Quality Water by Foam Fractionation

The removal of iron from Alaskan groundwaters by a foam fractionation technique has been shown to very effective. Finished waters with less than 0.2 mg/l iron have been produced from raw waters containing in excess of 25 mg/l. Ethylhexadecyldimethylammonium bromide was used as the principal foaming agent. Low temperature oxidation of the ferrous iron tended to interfere with the removal rates, but high temperature oxidation followed by low temperature fractionation did not exhibit the same adverse influence. All experiments were performed in four-liter laboratory batch columns. For the Alaskan environment batch processing is thought to have advantages over continuous processes because of the need for uncomplicated equipment.
• #### Tunnel lining studies II

In the CRREL tunnel (Fig. B1, B2), sublimation is extremely apparent, but because of the tunnels limited usage it poses no significant problems. However, in an operating mine with forced air ventilation and continuously operating machinery, the problems associated with sublimation may no longer be insignificant. The dust released by the evaporating ice poses not only the obvious respiratory threat, but an additional safety threat, as fine silt suspended in the air reduces visibility, and removal or suppression of the dust will be of importance.
• #### Two dimensional computational fluid dynamics model of pollutant transport in an open pit mine under Arctic inversion

A better understanding of the microscale meteorology of deep, open pit mines is important for mineral exploitation in arctic and subarctic regions. During strong temperature inversions in the atmospheric boundary layer--which are common in arctic regions during the winter--the concentrations of gaseous pollutants in open pit mines can reach dangerous levels. In this research, a two dimensional computational fluid dynamics (CFD) model was used to study the atmosphere of an open pit mine. The natural airflow patterns in an open pit mine are strongly dependent on the geometry of the mine. Generally, mechanical turbulence created by the mine topography results in a recirculatory region at the bottom of the mine that is detached from the freestream. The presence of a temperature inversion further inhibits natural ventilation in open pit mines, and the air can quickly become contaminated if a source of pollution is present. Several different exhaust fan configurations were modeled to see if the pollution problem could be mitigated. The two dimensional model suggests that mitigation is possible, but the large quantity of ventilating air required would most likely beimpractical in an industrial setting.
• #### Two-dimensional analysis of natural convection and radiation in utilidors

Central heating plants are often used on large building complexes such as university campuses or military bases. Utilidors can be used to contain heat distribution lines and other utilities between a utility station and serviced buildings. Traditional thermal analysis of utilidors is one-dimensional, with heat transfer correlations used to estimate the effects of convection, radiation, and two-dimensional geometric effects. The expanding capabilities of computers and numerical methods suggest that more detailed analysis and possibly more energy-efficient designs could be obtained. This work examines current methods of estimating the convection and radiation that occur across an air space in square and rectangular enclosures and compares them with numerical and experimental data. A numerical model was developed that solves the energy, momentum, and continuity equations for the primitive variables in two dimensions; radiation between free surfaces was also included. Physical experiments were conducted with two 10-ft-long apparatuses; one had a 1-ft $\times$ 1-ft cross section, the other was 2 ft $\times$ 4 ft. Several pipe sizes and configurations were studied with the 1-ft $\times$ 1-ft apparatus. The 2-ft $\times$ 4-ft apparatus was limited to containing 4- and 8-inch insulated pipes. Corresponding numerical studies were conducted. Difficulties in modeling large enclosures or those with large temperature differences (Rayleigh numbers above 10$\sp7$) were encountered. Results showed good agreement between numerical and experimental average heat transfer rates, and for insulated pipe cases these results also compared well with rates obtained from one-dimensional analysis. A new effective conductivity correlation for air in a square enclosure was developed, and its use was demonstrated in numerical conduction solutions and compared with full numerical convection and radiation solutions and with experimental data. Reasonably good results were achieved when there was a small temperature difference across the air gap.
• #### A two-layer energy-efficient wireless sensor network for precision agriculture applications

The agriculture industry has benefited from the recent technological evolution; for example, farmers now use satellite images to monitor large fields. The use of technology in agriculture, generally referred to as Precision Agriculture, has attracted a lot of research interest from electrical engineers. One particular area of Precision Agriculture is the application of embedded systems in monitoring large crop fields. Sensor nodes are placed at various locations in the field where they measure different parameters, such as temperature and soil moisture. The collected measurements are sent to a central hub outside of the field where they can be further processed and displayed for the farmers to make appropriate decisions. From the farmers' perspective, this kind of wireless sensor network (WSN) is a cost-effective solution that allows them to gather accurate information about their crops in real time and significantly improve production. To scientists, it provides invaluable information that can help them improve farming processes or even develop new crop varieties. From the embedded systems stand-point however, such a network poses several challenges, mainly battery life and network lifetime. Battery life is a serious challenge because nodes are scattered in the field and it would be labor intensive and expensive to replace their batteries. It is important to keep nodes alive because dead nodes not only fail to collect data but they also fail to relay packets from other active nodes. Radio communication draws most of the node's battery in WSN, so most energy saving techniques revolve around careful management of the radio. In this study, we focus on routing protocols that maximize the lifetime of the network. Most researchers have suggested various routing schemes to minimize battery consumption by finding the shortest path to a hub; however, when looking at the network as a whole, this approach may not be ideal. We present a lifetime-maximizing routing scheme that uses a cost function to distribute the traffic load among all nodes and to spare those with low remaining energy. The cost function being essential to our algorithm, we evaluate the impact of different types of cost function on the network lifetime. Lastly, we evaluate the impact of link quality in the cost function. Simulation results show that the power cost function has the best performance and that link quality can improve network lifetime. Another major contribution of this research is the design of a test framework that can be used to evaluate other routing protocols. In order to evaluate our routing protocol, we created a WSN simulation in Castalia. The simulation and the routing protocol are highly parametric and with minor modifications, users can experiment with new protocols or variations of ours. Using our platform can save users a lot of time and trouble, especially those unfamiliar with simulation tools, hence allowing them to focus their efforts on their protocol.
• #### Uncertainty in fish counting using an echo-counting technique as applied to data from a single-beam sonar

A model of fish distribution in time and space and a single-beam sonar model are presented. Simulated sonar data are obtained and analyzed using the echo-counting method to determine the estimated number of fish. The results show that (1) when the fish rate is less than 1 fish/s, the error is within plus minus 15% and fish are overcounted more often than undercounted, (2) this method underestimates the number of fish by 57% of the actual number of fish for a fish rate of 5 fish/s, (3) fish counts are dominated by the noise if the threshold is lower than the noise level, (4) by varying the ping rate, the error could be as much as 72% for a fish rate of 10 fish/s and a ping rate of 10 pings/s, (5) by varying the pulse width, the error could be as much as 80% for a fish rate of 10 fish/s and a pulse width of 1.0 ms.
• #### Uncertainty in fish location using a split beam sonar

The enumeration of fish is of critical importance to the management of both commercial and sport fisheries in Alaska and worldwide. Current methods for riverine fish enumeration are inaccurate and unreliable. Improved fish counting accuracy in Alaskan rivers by acoustic methods is required. A split beam sonar system in the presence of noise is modeled. The sonar system including the received sonar pulse, receiver system, transducer beam pattern, propagation losses, and noise are modeled. An analysis of the effects of noise, pulse duration and sampling frequency on the uncertainty in fish location is presented. Signal to noise ratios less than 5 dB can cause significant errors in the calculation of received signal phase. A stationary fish with a signal to noise ratio of 15 dB has approximately plus-minus 0.001 degrees of uncertainty in the angles of arrival. Reducing the SNR to 3 dB the uncertainty increases to plus-minus 3.6 degrees in the angles of arrival.
• #### Uncertainty quantification of gas production in the Barnett shale using time series analysis

Deterministic methods for evaluating uncertainty in production forecasts for unconventional shale plays are either unreliable or time intensive. This thesis presents an improved methodology for quantifying uncertainty in production forecasts using Logistic Growth Analysis (LGA) and time series modeling. The applicability of the proposed method is tested by history matching production data and providing uncertainty bounds for forecasts from eight Barnett Shale counties. The 80% confidence interval (CI) generated by this method successfully bracketed true production values for all the counties, even when approximately one-third of the data was used for history matching. In the methodology presented, the trend in the production data was determined using two different non-linear regression schemes. The predicted trends were subtracted from the actual production data to generate two sets of stationary residual time series. Time series analysis techniques (Auto Regressive Moving Average models) were thereafter used to model and forecast residuals. These residual forecasts were incorporated with trend forecasts to generate our final 80% CI. To check the reliability of the proposed method, I tested it on 100 gas wells with at least 100 months of available production data. The CIs generated covered true production 84% and 92% of the time when 40 and 60 months of production data were used for history matching, respectively. An auto-regressive model of lag 1 best fit the residual time series in each case. The proposed methodology is an efficient way to generate production forecasts and to reliably estimate uncertainty for short to medium time periods. It includes uncertainty due to parameter estimation using two different regression schemes. It also incorporates the uncertainty due to the variance of the residuals. The method is computationally inexpensive and easy to implement. The utility of the procedure presented is not limited to gas wells; it can be applied to any type of well or group of related wells.
• #### Understanding reservoir engineering aspects of shale gas development on the Alaska North Slope

Horizontal drilling and multi-stage hydraulic fracturing made it possible to develop US shale resources. Shublik shale is one of such US shale resources - it is one of the largest source rocks for hydrocarbon accumulations located on the Alaska North Slope. This study used the workflow introduced by Mirzaei and Cipolla in 2012 to investigate the effects of fracturing fluid flowback; shale porosity; matrix, fracture and unpropped zone permeability; hydraulic fracture spacing; permeability anisotropy; non-Darcy flow; gas adsorption/desorption using the complex-fracture-network model, referred to as an Unconventional Fracture Model (UFM), and Voronoi grid on well performance in the Shublik shale formation. In addition, the effects of natural fracture network orientation, fracture spacing and length were examined using a single porosity model with incorporated Discrete Fracture Network (DFN). The Schlumberger Mangrove Plug-In for Petrel platform was used to conduct the study. Mangrove has the DFN feature, which can be deactivated in the single porosity model. The results suggested that ignoring fracturing fluid flowback and non-Darcy effects can lead to overestimation of the gas recovery factor. Neglecting gas adsorption/desorption effects leads to underestimation of the gas recovery factor. In addition, smaller fracture spacing leads to a higher gas recovery factor. DFN orientation, fracture spacing and length affect the propped fracture area and should be incorporated into analysis from shale plays since it can result in either overestimation or underestimation of the gas recovery factor depending on fracture network propagation. Finally, examining multiple hydraulic fractures instead of one fracture is more accurate due to the stress shadowing effects and fracture network propagation.
• #### Understanding reservoir engineering aspects of shale oil development on the Alaska North Slope

Horizontal drilling and multi-stage hydraulic fracturing have made the commercial development of nano-darcy shale resources a success. The Shublik shale, a major source rock for hydrocarbon accumulations on the North Slope of Alaska, has huge potential for oil and gas production, with an estimated 463 million barrels of technically recoverable oil. This thesis presents a workflow for proper modeling of flow simulation in shale wells by incorporating results from hydraulic fracturing software into hydraulic fracture flow modeling. The proposed approach allows us to simulate fracture propagation and leak-off of fracturing fluid during hydraulic fracturing. This process honors the real proppant distribution, horizontal and vertical variable fracture conductivity, and presence of fracturing fluid in the fractures and surrounding matrix. Data from the Eagle Ford Shale in Texas was used for this modeling which is believed to be analogous to Alaska's Shublik shale. The performance of a single hydraulic fracture using a black oil model was simulated. Simulation results showed that for the hydraulically fractured zone, the oil recovery factor is 5.8% over thirty years of production, to an assumed economic rate of 200 STB/day. It was found that ignoring flowback overestimated oil recovery by about 17%. Assuming a constant permeability in the hydraulic fracture plane resulted in overestimation of oil recovery by almost 25%. The conductivity of the unpropped zone affected the recovery factor predictions by as much as 10%. For the case investigated, about 25% of the fracturing fluid was recovered during the first 2 months of production; in total, 44% of it was recovered over thirty years. Permeability anisotropy was found to have a significant effect on the results. These results suggest that assuming a constant conductivity for the fractures and ignoring the presence of water in the fractures and the surrounding matrix leads to overestimation of initial production rates and final recovery factors. In addition, the modified workflow developed here more accurately and seamlessly integrates the modeled induced fracture characteristics in the reservoir simulation of shale resource plays.
• #### A unified viscoplastic model for the inelastic behavior of ice

A physics-based SUVIC-I model is proposed for the ductile region of polycrystalline ice. It accounts for mixed hardening and directional softening using the three internal state variables - back stress, yield stress and drag stress. The main objective is to provide the best suitable material parameters for this model. The process to obtain these parameters is discussed in detail. The computational aspect of this model is implemented in the finite element program ABAQUS through a user subroutine UMAT for the axisymmetric and 3D models. The results are validated against the experimental data for constant strain rate and creep tests.
• #### Unmanned Aircraft System Assessments of Landslide Safety for Transportation Corridors

An assessment of unmanned aircraft systems (UAS) concluded that current, off-the-shelf UAS aircraft and cameras can be effective for creating the digital surface models used to evaluate rock-slope stability and landslide risk along transportation corridors. The imagery collected with UAS can be processed using a photogrammetry technique called Structure-from-Motion (SfM) which generates a point cloud and surface model, similar to terrestrial laser scanning (TLS). We treated the TLS data as our control, or “truth,” because it is a mature and well-proven technology. The comparisons of the TLS surfaces and the SFM surfaces were impressive – if not comparable is many cases. Thus, the SfM surface models would be suitable for deriving slope morphology to generate rockfall activity indices (RAI) for landslide assessment provided the slopes. This research also revealed that UAS are a safer alternative to the deployment and operation of TLS operating on a road shoulder because UAS can be launched and recovered from a remote location and capable of imaging without flying directly over the road. However both the UAS and TLS approaches still require traditional survey control and photo targets to accurately geo-reference their respective DSM.