Now showing items 380-399 of 918

• #### Ferric chloride leaching of the Delta sulfide ores and gold extraction from the leaching residue

Conventional differential and bulk flotation processes have difficulties in achieving high recoveries with acceptable grades far zinc, lead and copper from the complex sulfide ores found at Tok, Alaska. Furthermore, gold and silver, which account for a significant fraction of total value of the ores, are distributed evenly in the flotation tailings and concentrate. Therefore, processing both flotation tailings and concentrate would be necessary to obtain high recoveries of gold and silver. A mineralogical study revealed that the economic sulfide minerals are interstitially associated with a large preponderance of pyrite. The economic sulfide minerals are 10 to 40 microns in size. These mineralogical facts explain the difficulties encountered in the flotation process. A hydrometallurgical method involving ferric chloride leaching and subsequent steps to recover lead, zinc, silver and copper from the leach liquor has been studied at the Mineral Industry Research Laboratory, University of Alaska Fairbanks for the treatment of Delta ores. This alternative is attractive for processing complex sulfide ores which conventional flotation and smelting cannot handle. In addition, the liberation of sulfur in the environmentally acceptable elemental form, rather than as sulfur dioxide, may prove a major advantage of this hydrometallurgical method because of stringent environmental regulations.
• #### Fifth annual conference on Alaskan placer mining

An abridged format of papers, presentations and addresses given during the 1983 conference held on March 30-31, 1983 compiled and edited by Bruce W. Campbell, Jim Madonna, and M. Susan Husted.
• #### Final report - mineral resources of northern Alaska

PURPOSE. This is the final report on the work authorized on July 29, 1967, by the NORTH Commission. The purpose is to inventory mineral resources in northern Alaska and to delineate favorable mineral areas, insofar as possible. Later, a mineral policy study was added and a survey of available airborne geophysics. The Alaska Railroad made possible the large scale dredging at Fairbanks and became a feeder to all interior districts. It allowed the building of military bases during and after World War II. Freight moves predominantly north.

• #### Finite element analysis of yield functions of Kelvin foams with open cells

Proper design of foams requires an understanding of the response of the materials to stress. This thesis, based on finite element analysis, provides numerical solutions in modeling the yield behavior of Kelvin foams. The FEA model, representing a complicated unit cell, was calculated and meshed. C++ programs were designed and implemented to generate meshes for unit cells. Finite element analyses were performed for many cases. Multiple methods were employed for the determination of yield points which form yield surfaces. Comparisons between several results have been made. Our FEA results, Zhang's function and Gibson's theory show good agreements except some differences under hydrostatic loading. A conclusion can be made: besides the void fraction and the yield strength of the wall material, the structure of foams also has a significant effect on the yield behavior of foams. Yield surfaces normalized by the uniaxial tensile strength of foams are more reasonable.

This report summarizes work conducted with funds received from the Office of Water Research and Technology (OWRT), Project B-030-ALAS, Flood Frequency in Sparse-Data Regions. The study was conducted from July 1, 1974, to June 30, 1976, plus a one-year extension to June 30, 1977. The technical results are given in a number of publications which are referenced and abstracted here along with a presentation of the overall philosophy of the project and a coherent summary of the work. Alaska may be characterized, as can most northern areas, by a very sparse data collection network of hydrologic variables. In combination with several physical characteristics of northern hydrology, the sparse data network leads to a very difficult design circumstance. The most well known physical aspect of northern hydrology is permafrost. Other factors of importance are large elevation differences, regional inhomogeneity, high latitude, low temperatures, and the very dynamic nature of the spring breakup. These factors, in combination with the short data base in northern regions, cause hydrologic design to have a large degree of uncertainty.
• #### Flood Frequency Estimation in Northern Sparse Data Regions: Completion Report

The primary objective of this project was to complete development of an arctic hydrologic model and to evaluate its usefulness in generating information useful for a design tool in estimation of peak flow discharges. The peak flow discharges studied were those generally analyzed and evaluated in the design of facilities for stream crossings.
• #### Flood hazard hydrology: interdisciplinary geospatial preparedness and policy

Floods rank as the deadliest and most frequently occurring natural hazard worldwide, and in 2013 floods in the United States ranked second only to wind storms in accounting for loss of life and damage to property. While flood disasters remain difficult to accurately predict, more precise forecasts and better understanding of the frequency, magnitude and timing of floods can help reduce the loss of life and costs associated with the impact of flood events. There is a common perception that 1) local-to-national-level decision makers do not have accurate, reliable and actionable data and knowledge they need in order to make informed flood-related decisions, and 2) because of science--policy disconnects, critical flood and scientific analyses and insights are failing to influence policymakers in national water resource and flood-related decisions that have significant local impact. This dissertation explores these perceived information gaps and disconnects, and seeks to answer the question of whether flood data can be accurately generated, transformed into useful actionable knowledge for local flood event decision makers, and then effectively communicated to influence policy. Utilizing an interdisciplinary mixed-methods research design approach, this thesis develops a methodological framework and interpretative lens for each of three distinct stages of flood-related information interaction: 1) data generation—using machine learning to estimate streamflow flood data for forecasting and response; 2) knowledge development and sharing—creating a geoanalytic visualization decision support system for flood events; and 3) knowledge actualization—using heuristic toolsets for translating scientific knowledge into policy action. Each stage is elaborated on in three distinct research papers, incorporated as chapters in this dissertation, that focus on developing practical data and methodologies that are useful to scientists, local flood event decision makers, and policymakers. Data and analytical results of this research indicate that, if certain conditions are met, it is possible to provide local decision makers and policy makers with the useful actionable knowledge they need to make timely and informed decisions.
• #### Floodplain assessment for the Teklanika and Toklat River project reaches in Denali National Park and Preserve, Alaska

The National Park Service (NPS) is required to assess risks of flooding to existing and proposed structures within the boundaries of the NPS system. Within Denali National Park and Preserve (DNP & P), there are several large, braided rivers that require floodplain management. The objective of this investigation is to provide DNP & P with guidelines and methods that apply fluvial geomorphic, hydrologic, and hydraulic analysis in order to delineate flood hazard zones on this type of stream. Data collected from Teklanika and Toklat Rivers were used to develop a return period versus flood depth/bankfull depth curve and assess potential streambank erosion. Site specific data combined with this curve will enable NPS personnel to easily approximate flood hazard zones for the project reaches. The method can be applied to assess other flood hazard zones associated with other braided rivers with similar characteristics.
• #### Fluid flow in oscillating cavities

Oscillatory flows have gained considerable research attention in the recent decades following an interest in transport enhancement in micro-electronic devices. Heat transfer enhancement due to flow modulation has an inherent advantage over conventional mechanical heat transfer components in terms of reduction in weight and space. The present work is aimed at studying fluid flow in oscillating square cavities as a first step towards heat transfer enhancement. A commercial CFD code, Fluent, was used to model a test case consisting of Stokes' second problem, with a source code written in the C programming language. The simulated results were in good agreement with the analytical results found in the literature. Since the description of an oscillatory boundary condition in complex geometries would prove to be a difficult exercise because of the presence of spanwise walls, Newton's second law of motion for accelerating reference frames was used. This method proved to be an effective one computationally and the results agreed well with the analytical results. The cavity problem was analyzed using Fluent with the Non-Newtonian formulation described above. Fluid dynamic characteristics were studied with respect to dimensionless parameters and they exhibited an explicit dependence on these parameters.

• #### Focus on Alaska's coal '80, proceedings of the conference

The principal objectives of the conference were to bring together current knowledge on Alaska's coal resources, mining methods, utilization and marketing, and every interested party to share this knowledge. The excellent papers presented and the large number of participants indicates that the objectives were accomplished.
• #### Focus on Alaska's coal '86 - proceedings of the conference

This volume contains 35 papers presented at the two-day conference, "Focus on Alaska's Coal '86," held in Anchorage at the Hotel Captain Cook on October 28 and 29, 1986.
• #### Focus on Alaska's coal '93 - proceedings of the conference

This volume contains 20 of the 28 papers presented at the two-day conference, "Focus on Alaska's Coal '93," held in Anchorage at the Hotel Captain Cook on May 5-7; 1993. "Focus on Alaska's Coal '93" is the fourth in a series of conferences. "Focus on Alaska's Coal 1975" and "Focus on Alaska's Coal 1980" were held in Fairbanks, and "Focus on Alaska's Coal '86" was held in Anchorage. Their proceedings have been published.
• #### The formation of pore ice in coarse grained soils

Understanding the formation of pore ice in coarse grained soils is important to geotechnical and geo-environmental projects such as the construction of roads, airstrips and gravel foundations as well as the treatment of contaminated soils in the arctic, sub-arctic, alpine and northern regions. The amount of pore ice present controls the strength characteristics of the soils as well as the flow of fluid through the soil. Tests have been conducted to qualify the impact of gradation, temperature, compaction and initial moisture content on the formation of pore ice in coarse grained soils. The purpose of this study was to prepare a conceptual model of the freezing mechanism in coarse grained soils and to qualify the parameters that influence the ice formation. Results from this study indicate that the presence of fine grained particles in a coarse grained soil greatly impact the depth at which the pore space initially becomes saturated with ice. A conceptual model was developed and its application is shown with regards to the process of thaw weakening in roads and the creation of preferential flow paths in permeable reactive barriers.
• #### Fortran IV program for processing geochemical sediment data, 34 p.

A general computer program has been written to process geochemical data resulting from the analysis of up to 34 trace elements per sample. This program will: 1. Produce a table for direct inclusion in formalreports. The table contains the map number and field number of the geochemical samples, the corresponding elemental values and a table giving descriptive data about the sample. Prior to printing, the samples are arranged according to map number for easy correspondence between the table of values and to the geochemical map. 2. Compute the average value for each element, normally and lognormally. 3. Compute the standard deviation for each element, normally and lognormally. 4. Compute the threshold value for each element, normally and lognormally. 5. Compute the anomalous concentrations for each element, normally and lognormally. 6. Draw lognormal, or standard histograms for each element. All geochemical samples taken by the Alaska Division of Mines and Geology during the summer of 1968 and 1969 were processed by this program or a modification of the program. The program can be modified to enable production of automatic maps and tables of anomalous samples.
• #### Fortran IV trent-surface program for the IBM 360 model 40 computer

A Fortran IV trend surface program with polynomial contouring and residual plotting has been adapted to the University of Alaska IBM 360 Model 40 Computer. The program will compute equations of polynomials of the first through sixth degree, measures of the goodness of fit of the surfaces, tabulate original data, x y coordinates and corresponding residuals for each surface; contour each polynomial, and plot original values and residuals for each surface computed.
• #### Fourth annual conference Alaskan placer mining

An abridged format of papers, presentations and addresses given during the conference held on March 30-31, 1982, compiled and edited by: Bruce W. Campbell, John J. DiMarchi, and Ernest N. Wolff.
• #### Fracture and shakedown of pavements under repeated traffic loads

Under repeated external loads, engineering structures or objects may fail by large plastic deformation or fatigue. Shakedown will occur when the accumulation of plastic deformation ceases under repeated loads; the response of the system is then purely elastic. Fatigue and shakedown have been individually studied for decades and no attempt has been made to couple these two mechanisms in the mechanics analysis. In this study, an attempt is made to couple shakedown and fatigue in pavement mechanics analysis using numerical simulation. The study covers three main areas: fatigue, static shakedown, and kinematic shakedown analysis. A numerical approach to fatigue analysis is proposed based on elastic-plastic fracture mechanics. The amount of the crack growth during each load cycle is determined by using the J-integral curve and $\rm R\sb{-}curve.$ Crack propagation is simulated by shifting the $\rm R\sb{-}curve$ along the crack growth direction. Fatigue life is predicted based on numerically estabiished fatigue equation. The numerical results indicate that the algorithm can be applied to fatigue analyses of different materials. A numerical algorithm based on the finite element method coupled with the nonlinear programming is proposed in static shakedown analysis. In this algorithm, both the inequality and equality constraints are included in the pseudo-objective function. These constraints are normalized by the material yield stress and the reference load, respectively. A multidirectional search algorithm is used in the optimization process. The influence of finite element mesh on shakedown loads is investigated. An algorithm that utilizes eigen-mode to construct the arbitrary admissible plastic deformation path is proposed in kinematic shakedown analysis. This algorithm converts the shakedown theorem into a convex optimization problem and can be solved by using a multidirectional search algorithm. Fatigue behavior of a two-layer full-depth pavement system of asphalt concrete is analyzed using the proposed numerical algorithm. Fatigue crack growth rate is estimated and fatigue life is predicted for the system. Shakedown analyses are also carried out for the same pavement system. The comparison between the shakedown load and the fatigue failure load with respect to the same crack length indicates that the shakedown dominates the response of the pavement system under traffic load.
• #### FRAM based low power systems for low duty cycle applications

Ferro-Electric Random Access Memory (FRAM) is a leap forward in non-volatile data storage technology for embedded systems. It allows for persistent storage without any power consumption, fulfilling the same role as flash memory. FRAM, however, provides several major advantages over flash memory, which can be leveraged to substantially reduce sleep current in a device. In applications where most of the time is spent sleeping these reductions can have a large impact on the average current. With careful design sleep currents as low as 72 nA have been demonstrated. A lower current consumption allows for more flexibility in deploying the device; smaller batteries or alternative power sources can be considered, and operating life can be extended. FRAM is not appropriate for every situation and there are some considerations to obtain the maximum benefit from its use. An MSP430FR2311 microcontroller is used to measure the performance of the FRAM and how to structure a program to achieve the lowest power consumption. Clock speed and instruction caching in particular have a large effect on the power consumption and tests are performed to quantify their effect. Two case studies are considered, a feedback control system and a data logger. Both cases involve large amounts of data writes and allow for the effects of the FRAM to be easily observed. Expected battery life is determined for each case when the sample rate is varied, suggesting that average operating current for the two solutions will nearly converge when the sampling period exceeds 1000 s. For sampling periods on the order of one second operating current can be reduced from 15.4 μA to 730 nA by utilizing FRAM in lieu of flash.