The design characteristics of an active waste disposal capsule placed within a saturated groundwater environment is investigated, with the objective of developing a methodology to determine environmentally, technically and economically feasible conditions for its operation. In operation, conditions are created and maintained within and surrounding a containment cell to insure that a potential for convective inflow exists everywhere across an encapsulating barrier which tends to counter the potential for outward dispersion through the barrier. A computer algorithm based on the finite element method has been developed in the BASIC language to aid in the hydraulic analysis. Essentially, it provides a numerical solution to potential flow through porous media for two dimensional anisotropic solution domains of various materials. Data generated from this algorithm for cases of varying geometric material and boundary properties are used to verify and quantify assumed relationships involving critical design parameters which have been developed through dimensional analysis and physical reasoning. An expression describing the concentration profiles developed across the barrier is obtained by solving the one-dimensional convection-dispersion equation for steady conditions within and bounding the capsule barrier. Applying this result to an identified critical point allows conservative barrier design criteria to be developed so that operation of the active capsule results in only negligibly small amounts of contamination escaping through the barrier to the environment. By introducing cost coefficients which are descriptive of various aspects of construction, operation and maintenance of the active capsule, a total cost function is formulated from which, when minimized with respect to various design variables, optimizing criteria are developed. Finally, a predictor-corrector optimization program which incorporates the results of this study is developed and used to investigate an illustrative problem. / M.S.

For a successful CubeSat mission, it is imperative to schedule events in a fashion that will generate maximum useful science data. Intuitive uplink commanding software is required for the Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat to ensure best results. The ground station up-link software is created with this aim in mind. This will make the operation center for the LAICE project efficient. This will also help in evaluating the effect of a particular schedule on LAICE instrument interface board (LIIB) before sending the commands to it. The interactive User Interface (UI) that makes the entire process intuitive guides the user to create an uplink schedule without any human error. The control software creates the command sequence taking in to account all the limitations and specification of the systems and instruments on LAICE. These data are backed up in an efficient format in Virginia Tech’s database for future processing. This web-based application ensures a smooth scheduling process without any errors. Assistive flight-ready software is provided on the flight computer on the LAICE CubeSat to upload the correct uplink sequence to the LIIB. / Master of Science

Previous research relating to alum sludge land application has primarily been restricted to laboratory studies of short-term environmental effects. In general, most research has concluded that the environmental effects of alum sludge constituents can be easily controlled. This study investigated the fate of land-applied alum sludge constituents nearly three years after incorporation into a Slagle soil. An existing field site was used. The site had been used for a pilot study examining the land application of alum sludge from the Harwood's Mill Water Treatment Plant in Newport News, Virginia. Alum sludge and lime were applied to the site in November, 1989. Soil, soilwater, groundwater and pine needle tissue media were sampled during the summer of 1992. It was determined that the alum sludge posed no observable long-term threat to groundwater quality or vegetative productivity. Migration of alum sludge constituents through the soil profile could not be confirmed in this research. However, acid precipitation may have destroyed the alkalinity added to the soil. Thus, long-term management of alum sludge land application to acid soils may require additional increments of alkalinity. / Master of Science

This paper describes the design and simulation of a microwave band, high resolution imaging ground penetrating radar. A conceptual explanation is given on the mechanics of wave-based imaging, followed by the governing radar equations. The performance specifications for the imaging system are given as inputs to the radar equations, which output the full system specifications. Those specifications are entered into a MATLAB simulation, and the simulation results are discussed with respect to both the mechanics and the desired performance. Finally, this paper discusses limitations of the design, both with the simulations and anticipated issues if the device is fully realized. / Master of Science

Appalachia requires design guidelines for the increasingly popular multi-seam longwall method. Entry layouts often depart from the ideal when finally developed. The thesis examines the occurrence of ground control problems, and possibilities for improvements in strata control, in a variety of undermining situations. The effects of upper seam loading on undermining operations are invest~gated using physical modelling. Photoelastic stress analysis is used as a powerful research tool to analyze complex multiple seam entry systems. Yield pillar use is also examined, in anticipation of their widespread application for ground control. Case examples support the research findings, and specific conclusions aim to assist layout design in interactive zones. / Master of Science

Seismic hazard assessment of intersecting fault systems, such as the strike-slip and reverse faults of the Los Angeles basin, is hindered by complex patterns of rupture that are currently difficult to predict. To improve this understanding, constraints on the previous rupture patterns of such systems are needed. The junction between the Transverse Ranges and the Eastern California shear zone in southern California provides a natural analog to the seismic setting of the Los Angeles basin. Along the northern flank of the San Bernardino Mountains, the east-west trending North Frontal thrust system is intersected by several northwest trending dextral faults of known Holocene and historical rupture activity. This structural setting, along with an apparent decay in uplift rate along the thrust (from a 3-Myr average of 0.5 mm/yr to a late Pleistocene rate estimated as slow as 0.05 mm/yr), suggests the thrust system may have been rendered inactive by the shear zone that dissects it. However, a clear cross-cutting relationship does not exist, raising the possibility that the two systems are coactive. To test this, we have constrained the recent rupture history of one thrust fault segment with paleoseismic investigations. We have excavated an apparently young thrust fault scarp along the central portion of the thrust system, chosen as the most likely to have ruptured in the recent past. At this location, just west of the intersection of the Helendale fault, a 7-m-high thrust scarp in older fanglomerate is dissected and replaced by younger alluvium with a 1.5-m-high scarp. An excavation across the smaller scarp revealed a 3-m-thick sequence of coarse alluvium cut by a shallow, south-dipping thrust fault with 1.65 m of throw. The simple, smooth trace of the fault plane and the lack of evidence for repeated deformation suggest the offset was produced by one event. A maximum age for this event is provided by disagregated detrital charcoal sampled from a sand lens in the lowermost gravel of the hangingwall, which yielded a calibrated radiocarbon age of 9220 BC (11220 yr BP). Subsequent to this inferred depositional age, an additional 2-m of gravel was deposited prior to fault rupture. Although a minimum age is not constrained, the event may thus have been as young as mid- to late-Holocene, consistent with the poor degree of soil development in several buried soil horizons in the alluvium. This indicates that at least part of the thrust system is coactive with the strike-slip strands that intersect it and implies that such intersections do not require either fault system to be extinct. However, it is crucial to obtain a minimum age in order to constrain the recent rupture history. This is inherently difficult because where the required onlapping relationships are present, scarps associated with the most recent event have been buried or eroded. A second site does occur several km from our original site, yet without knowing the exact location or depth of the fault an excavation would be risky. To increase the likelihood of finding the fault with an excavation, we employed geophysical exploration techniques to image the fault at depth. Ground Penetrating Radar (GPR) is a technique that can be used for shallow high-resolution imaging by recording the propagation of radio waves. To calibrate this technique to locating a shallow fault in the conditions of the study area, we returned to the site of our original excavation. We observed reflections from subhorizontal strata and the fault plane extending to a depth ~10 meters. This was identical to our initial trench observations. Using the same technique at our candidate minimum-age site, we resolved the exact location of a dipping fault plane covered by several meters of young alluvium. Now that the fault has been located, excavation of the site can be undertaken with a good chance of success. This result shows the value of GPR being used as an innovative predictive tool in paleoseismology. / Master of Science

Underground coal mine ground control persists as a unique challenge in rock mass engineering. Fall of roof and rib continue to present a hazard to underground personnel. Stability of underground openings is a prerequisite for successful underground coal mine workings. An adaptation of a civil engineering design standard for analyzing the stability of underground excavations for mining geometries is given here. The ground response curve--developed over seventy years ago for assessing tunnel stability--has significant implications for the design of underground excavations, but has seen little use in complex mining applications. The interaction between the small scale (pillar stress-strain) and the large scale (ground response curve) is studied. Further analysis between these two length scales is conducted to estimate the stress on pillars in a room-and-pillar coal mine. These studies are performed in FLAC3D by implementing a two-scale, two-step approach. This two-scale approach allows for the interaction between the small, pillar scale and the large, panel scale to be studied in a computationally efficient manner. / Ph. D.

Unmanned Aerial Vehicles (UAV) are expected to be deployed both by government and industry. Rules for integrating commercial UAVs into a nation's airspace still need to be defined, safety being the main concern. As part of this thesis, the communication needs of UAVs as important requirement for UAV integration into the national airspace is considered. Motivated by recent prediction of UAV quantities, revealing the importance of Micro UAVs (MAV) and Small UAVs (SUAV), the thesis determines spectral requirements for control and non-payload communication (CNPC). We show that spectral efficiency, particularly in the downlink, is critical to the large-scale deployment of UAVs. Due to the limited range of small SUAV and MAV systems, communication between air and ground elements of these UAVs is established through radio Line-of-Sight (LoS) links. Ultimately, efficient LoS UAV systems are based on a better understanding of channels in the downlink, i.e. air-to-ground (A2G) channels, and also on efficient waveform as well as spectrum management implementation. Because of limited research in wideband aeronautical channel modeling, we have derived an A2G channel prototype applicable to SUAV and MAV. As part of the research at Wire- less@VT in designing and prototyping Orthogonal Frequency Division Multiplexing (OFDM) waveforms, this thesis derives the optimal parameters for SUAV and MAV A2G channels. Finally, the thesis discusses concepts that relate flight route with spectrum management as well as opportunities for a more dynamic spectrum allocation for UAV communication systems. / Master of Science

Ground transportation systems are essential for the mobility of people, goods and services. Thus, making sure these systems are resilient to the impact of natural and man-made disasters has become a top priority for engineers and policy makers. One of the major obstacles for increasing the resilience of ground transportation systems is the lack of a measuring framework. Such measuring framework is critical for identifying needs, monitoring changes, assessing improvements, and performing cost-benefit analysis. This research addresses this problem by developing a traffic-based framework for measuring the resilience of ground transportation systems under normal and extreme conditions. The research methodology consisted of: (1) creating a microscopic traffic model of the road under study, (2) simulating different intrusions and interventions, and (3) measuring the resilience of the system under the different scenarios using the framework developed. This research expanded the current definition of infrastructure resilience, which includes the assessment of system performance versus time, to add a third dimension of resilience for ground transportation system's applications, namely: location. This third dimension considers how the system changes along the different locations in the network, which reflects more accurately the continuous behavior of a ground transportation network. The framework was tested in a 24 km segment of Interstate 95 in Virginia, near Washington, D.C. Four hazard conditions were simulated: inadequate base capacity, traffic incidents, work zones, and weather events. Intervention strategies tested include ramp meters and the use of the shoulder lane during extreme events. Public policy was also considered as a powerful intervention strategy. The findings of this research shed light over the current and future resilience of ground transportation systems when subject to multiple hazards, and the effects of implementing potential interventions. / Ph. D.

The KiK-net ground motion database is used to develop ground motion prediction equations for Arias Intensity (I_a), 5-95% Significant Duration (Ds_5-95), and 5-75% Significant Duration (Ds_5-75). Relationships are developed both for shallow crustal earthquakes and subduction zone earthquakes (hypocentral depth less than 45 km). The models developed consider site amplification using V_S30 and the depth to a layer with V_S=800 m/s (h₈₀₀). We observe that the site effect for I_α is magnitude dependent. For Ds_5-95 and Ds_5-75, we also observe strong magnitude dependency in distance attenuation. We compare the results with previous GMPEs for Japanese earthquakes and observe that the relationships are similar. The results of this study also allow a comparison between earthquakes in shallow-crustal regions, and subduction regions. This comparison shows that Arias Intensity has similar magnitude and distance scaling between both regions and generally Arias Intensity of shallow crustal motions are higher than subduction motions. On the other hand, the duration of shallow crustal motions are longer than subduction earthquakes except for records with large distance and small magnitude causative earthquakes. Because small shallow crustal events saturate with distance, ground motions with large distances and small magnitudes have shorter duration for shallow crustal events than subduction earthquakes.