A Versatile Shotgun Source for Engineering and Groundwater Seismic Surveys

We describe an electrical seismic gun that is capable of firing 8-gauge blank black powder shells in a water-filled borehole under relatively high hydrostatic pressures. The new seismic gun is a modified version of the electrical shotgun source for engineering seismic surveys introduced by Pullan and MacAulay (1987). Our modifications seal the firing circuit and 8-gauge shell against water entry so underwater detonation will occur reliably at depths to at least 80 m (0.9 MPa atmospheric pressure). Source energy is controlled by varying the size of the black powder load in the shell from 50 grains to 500 grains (10 kJ to 100 kJ). Although our seismic gun may be used in any seismic application suitable for modest explosive charges, it was initially developed as a versatile source for use in seismic investigations of the shallow subsurface (primarily engineering and groundwater studies). As of this writing, the gun has been used for optimum offset and CMP high-resolution seismic reflection profiling, engineering refraction surveys, fixed-source and variable-source noise tests, and vertical traveltime measurements in water wells. Other potential uses include VSP and borehole-to-surface or borehole-to-borehole seismic tomography

Ground stone lithic technology of the Indian Peaks, Colorado, USA

2013 Fall.Includes bibliographical references.Ground stone tools are a long-noted aspect of pre-contact archaeological assemblages from the high elevations (2975-3666 meters asl) of the Colorado Front Range (CFR). The tools are present in small frequencies at around 40% of the sites thus far recorded, and are typically present as heavily fragmented grinding slab fragments procured many kilometers east and meters of relief lower than the study area and a combination of local and non-local handstones in a wide array of morphological configurations. Compared to their chipped stone counterparts, ground stone tools typically comprise a small percentage of archaeological assemblages, and have thus been reported in a largely cursory fashion. Though the ground stone assemblage from a single site is too small and perhaps too homogenous to inform large-scale questions, they take on increased interpretive potential when synthesized in aggregate and on a regional scale. Drawing from a distributional approach to archaeology and a technological approach to artifact analysis, the present study addresses the behavioral implications of ground stone tool presence in the high altitudes of the CFR by employing a three-tiered morphological, temporal, and spatial analysis. A technological analysis of ground stone tools (chapter 4) is centered upon answering two primary research questions catered towards understanding the function and technological organization of the high altitude ground stone toolkit. Firstly, the idea that handstones were technologically flexible in function is tested through comparison of the size of and diversity of modifications present on local and non-local handstones. It is determined that non-local handstones are significantly smaller in mass than local handstones, and were thereby chosen for inclusion into mobile toolkits on this basis. However, contrary to expectations of a flexible tool, non-local handstones contain less diversity of modifications than local handstones, suggesting that they were transported for some specialized purpose that local handstones could not fulfill. For netherstones, the idea that some were used as cooking stones is tested, given the assumption that thinner stones would function better for this task and would subsequently exhibit thermal alteration on a more frequent basis. This hypothesis is not proven, suggesting that thermal alteration of grinding slabs is not related to use as cooking stones, or that thickness is not related to grinding slabs' function as cooking stones. A temporal analysis (chapter 5) is conducted to test a prior model of high altitude land use that anticipates a greater diversity of ground stone tool forms will be present in assemblages of early Archaic age, during which residential use of the study area is proposed to have increased in response to climate change. It is determined that, though this period contains the greatest diversity of ground stone tool forms both in terms of handstone morphology and grinding slab thickness, that diversity is almost entirely a function of sample size. The implications of these results are discussed and several needs for future diachronic studies in the region are called for. Finally, a distributional analysis (chapter 6) of ground stone tool presence is undertaken in order to test current models of land use for the Colorado Front Range; the 'rotary' model expects a largely random distribution of ground stone tools and the 'up-down' model expects a largely patterned distribution. It is determined that there are significant differences in the presence of ground stone tools between major ecological zones, and that each zone is provisioned with different ground stone tools types in roughly the same manner. Further, this significant difference is directional, and patterned in terms of the diversity of edible plants located within each ecological zone. These results are interpreted to be most supportive of an 'up-down' model of prehistoric land use

Radiation pattern of a ground-plane mounted parallel-plate waveguide analyzed by a surface integration technique

Surface integration analysis of radiation pattern of parallel plate waveguid

Use of ERTS-1 data in the educational and applied research programs of agricultural extension

There are no author-identified significant results in this report

An Electrically Detonated Downhole Seismic Gun

An electrically detonated downhole seismic gun (EDG) that will fire blank 8-guage shells underwater has been constructed and tested to 80m depth (hydrostatic pressures of 130 psi or 8.9 x 105 Pa). Although other engineering seismic guns which fire blank or projectile sources are available, they are for near-surface shots and are not meant to be used for downhold seismic surveys in water-filled boreholes. The EDG was designed primarily for checkshot surveys (well travel-time surveys) and high-quality reflection/refraction tests, but potential applications include shallow vertical seismic profiling and borehole to borehole or borehole to surface tomography, as well as optimum offset and common midpoint seismic reflection surveys. The EDG consists off four steel subassemblies: (1) chamber; (2) breech; (3) pipe; and (4) hanger. A blank 8-gauge electrical shell is held by the chamber and is detonated by an electrode located inside the breech. O-ring seals prevent water from entering the breech and causing short circuits. The breech is screwed into a pipe which is also fitted with o-ring seals to keep the internal wiring dry. A hanger subassembly provides a convenient attaching point for the hoist cable. Arming of the EDG with an explosives blaster occurs only after lowering to operating depth. The EDG has been tested with various size black powder loads up to 750 grains. Frequency bandwidth and repeatability tests were carried out under saturated conditions in a fluvial and lacustrine sedimentary section. These preliminary tests show significant frequency content in the 25-200 Hz band (peak near 100 Hz) for reflections from depths of 150-300 m, and acceptable waveform repeatability for different shot records obtained with identical geometry and acquisition parameters

Correlates of Success for On-Site Releases of Nuisance Black Bears in Great Smoky Mountains National Park

Since 1990, wildlife biologists in Great Smoky Mountains National Park (GSMNP) have used capture and on-site release as a management technique to reduce recurrence of nuisance activity by black bears (Ursus americanus). On-site release involves capture and immobilization of bears that frequent developed areas, collection of biological data, and subsequent release in the area of capture. Our objective was to identify factors related to success of this technique. We classified 85 on-site releases of black bears as successes or failures based on post-release observations and subsequent management actions at the release site. The success rate of on-site releases in GSMNP (58 - 73% for the 3 classifications of success) indicates the overall effectiveness of this technique. We examined 11 variables for their associations with release success. Important variables associated with success of on-site releases were sex, presence of young, type of developed area where capture occurred, time of day that the bear was active in developed areas, and bear population abundance. Our results indicate on-site releases were most effective when bears were captured early in their progression towards nuisance behavior; on-site releases of night-active bears were 4.0 times less likely to require further management actions and at least 7.6 (lower limit of the 95% CI) times less likely to be relocated than day-active bears. Our results further indicate females with young may be the most difficult to deter from developed areas. Therefore, to avoid relocation of a family group, early detection and capture of females with young may be particularly important. Given various scenarios of nuisance bear activity, biologists can use our findings to determine when on-site release is appropriate

Effects of Hydrogen on the Phases and Transition Temperatures of NiTi

Austenitic (B2) NiTi samples were cathodically charged with various amounts of hydrogen. Trends are tracked based on temperature, time and voltage throughout the process to establish consistent and predictive hydrogen charging procedures. The effect of hydrogen on the austenitic structure and the formation of hydrides are studied with x-ray diffraction (XRD). An increase in the austenite lattice parameter with increased hydrogen content is observed up to a hydrogen solubility limit of approximately 85 wppm. At greater hydrogen concentrations, additional XRD peaks appear, suggesting possible hydride formation. Differential scanning calorimetry (DSC) results show a decrease in both the austenitic and martensitic transition temperatures with increased atomic hydrogen content and increased hydride phase. Scanning electron microscopy (SEM) is used to reveal the hydride phase. The effect of atomic hydrogen on NiTi and the structure of the hydride phase are compared with previous hydrogen studies

Evidence for a diffusion-controlled mechanism for fluorescence blinking of colloidal quantum dots

Fluorescence blinking in nanocrystal quantum dots is known to exhibit power-law dynamics, and several different mechanisms have been proposed to explain this behavior. We have extended the measurement of quantum-dot blinking by characterizing fluctuations in the fluorescence of single dots over time scales from microseconds to seconds. The power spectral density of these fluctuations indicates a change in the power-law statistics that occurs at a time scale of several milliseconds, providing an important constraint on possible mechanisms for the blinking. In particular, the observations are consistent with the predictions of models wherein blinking is controlled by diffusion of the energies of electron or hole trap states

A calcium ion in a cavity as a controlled single-photon source

We present a single calcium ion, coupled to a high-finesse cavity, as an almost ideal system for the controlled generation of single photons. Photons from a pump beam are Raman-scattered by the ion into the cavity mode, which subsequently emits the photon into a well-defined output channel. In contrast with comparable atomic systems, the ion is localized at a fixed position in the cavity mode for indefinite times, enabling truly continuous operation of the device. We have performed numeric calculations to assess the performance of the system and present the first experimental indication of single-photon emission in our set-up