Impact of tailings subsidence on rehabilitated landform erosional stability

As a mine gets closer to the end of its productive life, rehabilitation of the site for its release back into the surrounding environment involves disposal of toxic, saturated fine grained tailings derive from ore processing. Tailings disposal back into the excavated pit and capping the site with a landform to isolate them from the environment is an accepted method of mine rehabilitation. The predicted long term stability of the landform due to the influence of tailings compression is a key factor to be considered in the design of the landform. The project investigates the settlement that had occurred at a mine site that was rehabilitated using this method of rehabilitation. The total settlement of the landform is quantified by comparing historical surface information to the existing surface level as determined by conducting a topographic survey. Current griding and mapping technology were also used to assist in the quantifying process. Using historic mine, landform design and construction information a consolidation model is presented base on Terzaghis one dimesional consolidation theory. This model is then calibrated to the landforms maximum recorded settlement. The findings presented provide a basis for further development towards designing capped tailings landforms with long term stability

Cosmic bubble and domain wall instabilities III: The role of oscillons in three-dimensional bubble collisions

We study collisions between pairs of bubbles nucleated in an ambient false vacuum. For the first time, we include the effects of small initial (quantum) fluctuations around the instanton profiles describing the most likely initial bubble profile. Past studies of this problem neglect these fluctuations and work under the assumption that the collisions posess an exact SO(2,1) symmetry. We use three-dimensional lattice simulations to demonstrate that for double-well potentials, small initial perturbations to this symmetry can be amplified as the system evolves. Initially the amplification is well-described by linear perturbation theory around the SO(2,1) background, but the onset of strong nonlinearities amongst the fluctuations quickly leads to a drastic breaking of the original SO(2,1) symmetry and the production of oscillons in the collision region. We explore several single-field models, and we find it is hard to both realize inflation inside of a bubble and produce oscillons in a collision. Finally, we extend our results to a simple two-field model. The additional freedom allowed by the second field allows us to construct viable inflationary models that allow oscillon production in collisions. The breaking of the SO(2,1) symmetry allows for a new class of observational signatures from bubble collisions that do not posess azimuthal symmetry, including the production of gravitational waves which cannot be supported by an SO(2,1) spacetime.Comment: 35 pages + references, 26 figures. Submitted to JCAP. v2: Acknowledgments updates, no other change

Cosmic bubble and domain wall instabilities II: Fracturing of colliding walls

We study collisions between nearly planar domain walls including the effects of small initial nonplanar fluctuations. These perturbations represent the small fluctuations that must exist in a quantum treatment of the problem. In a previous paper, we demonstrated that at the linear level a subset of these fluctuations experience parametric amplification as a result of their coupling to the planar symmetric background. Here we study the full three-dimensional nonlinear dynamics using lattice simulations, including both the early time regime when the fluctuations are well described by linear perturbation theory as well as the subsequent stage of fully nonlinear evolution. We find that the nonplanar fluctuations have a dramatic effect on the overall evolution of the system. Specifically, once these fluctuations begin to interact nonlinearly the split into a planar symmetric part of the field and the nonplanar fluctuations loses its utility. At this point the colliding domain walls dissolve, with the endpoint of this being the creation of a population of oscillons in the collision region. The original (nearly) planar symmetry has been completely destroyed at this point and an accurate study of the system requires the full three-dimensional simulation.Comment: 23 pages + references, 13 figures. Submitted to JCAP. v2: Acknowledgements updated, no other change

Cosmic bubble and domain wall instabilities I: parametric amplification of linear fluctuations

This is the first paper in a series where we study collisions of nucleated bubbles taking into account the effects of small initial (quantum) fluctuations in a fully 3+1-dimensional setting. In this paper, we consider the evolution of linear fluctuations around highly symmetric though inhomogeneous backgrounds. We demonstrate that a large degree of asymmetry develops over time from tiny fluctuations superposed upon planar and SO(2,1) symmetric backgrounds. These fluctuations arise from zero-point vacuum oscillations, so excluding them by enforcing a spatial symmetry is inconsistent in a quantum treatment. We consider the limit of two colliding planar walls, with fluctuation mode functions characterized by the wavenumber transverse to the collision direction and a longitudinal shape along the collision direction $x$, which we solve for. Initially, the fluctuations obey a linear wave equation with a time- and space-dependent mass $m_{eff}(x,t)$. When the walls collide multiple times, $m_{eff}$ oscillates in time. We use Floquet theory to study the fluctuations and generalize techniques familiar from preheating to the case with many coupled degrees of freedom. This inhomogeneous case has bands of unstable transverse wavenumbers $k_\perp$ with exponentially growing mode functions. From the detailed spatial structure of the mode functions in $x$, we identify both broad and narrow parametric resonance generalizations of the homogeneous $m_{eff}(t)$ case of preheating. The unstable $k_\perp$ modes are longitudinally localized, yet can be described as quasiparticles in the Bogoliubov sense. We define an effective occupation number to show they are created in bursts for the case of well-defined collisions in the background. The transverse-longitudinal coupling accompanying nonlinearity radically breaks this localized particle description, with nonseparable 3D modes arising.Comment: 37 pages + references, 20 figures, submitted to JCA

Probable Displacement of Riffle-Dwelling Invertebrates by the Introduced Rusty Crayfish, \u3ci\u3eOrconectes Rusticus\u3c/i\u3e (Decapoda: Cambaridae) in a North-Central Wisconsin Stream

The rapid northward range expansion of the rusty crayfish, Orconectes rusticus, and its negative effects on Wisconsin lakes have been the subjects of intense study throughout the last fifteen years. In this study, we investigated the possible impact of rusty crayfish on the benthic macroinvertebrate community structure of the Prairie River in north-central Wisconsin. Rusty crayfish and other invertebrates were collected during August and September, 1994, from three sections of the Prairie River. Rusty crayfish relative abundance increased significantly from the upper to middle, and middle to lower sections; and correlated negatively with a significant 77% decrease in total density of aquatic invertebrates between sections. Mean density of all important invertebrate families and trophic guilds decreased significantly between the upper and lower sections. Due to the similarity of most environmental conditions between river sections, decrease of invertebrates is attributed to the increased abundance of rusty crayfish and its interactions with the native rouna. Our results suggest that a high abundance of rusty crayfish may negatively impact Wisconsin lotic systems

A Case Study of the Environmental Impacts of the Beddown of the C-17 Globemaster III at Charleston AFB

Unites States Air Force acquisition environmental planning has changed significantly since the passage of the National Environmental Policy Act in 1969. This research examined the role of environmental planning in weapon system acquisition. It focused on environmental planning performed for the C-17 Globemaster III prior to its beddown at Charleston Air Force Base. The case study of the C- 17 beddown included interviews, archival record reviews, and direct observations at the base. Evidence was collected to determine what environmental impacts occurred during the beddown. An environmental postaudit compared actual impacts with those predicted in environmental planning documentation. Impacts were analyzed to determine if they resulted from local conditions or requirements. A framework of the acquisition process was constructed and environmental requirements were flowcharted. A timeline of C-17 events was developed for comparison of C-17 history with an ideal acquisition process. Finally, environmental planning documentation was evaluated using 20 objective criteria to determine its quality. Two minor impacts were identified at Charleston AFB during data collection in June 1995 - two years after the first C- 17 arrived there. Impacts did not result from unique local conditions. Recommendations were presented regarding the quality and timing of weapon system environmental planning

Strain sensing using optical fibers

The main source of attenuation which will be studied is the optical fiber's sensitivity to bending at radii that are much larger than the radius of the fiber. This type of environmental attenuation causes losses that are a function of the severity of the bend. The average attenuation caused by bending varies exponentially with the bend radius. There are many different fibers, sources, and testing equipment available. This thesis describes tests that were performed to evaluate the variables that effect bending related attenuation and will discuss the consistency of the results. Descriptions and comparisons will be made between single mode and multimode fibers as well as instrumentation comparisons between detection equipment. Detailed analysis of the effects of the whispering gallery mode will be performed along with theorized methods for characterization of these modes