The main purpose of this diploma thesis was to determine whether the deformation zone, which arises above intact mining workings in soils, has a measurable gravity effect and influences the interpretation of gravity measurements. The railway tunnel in Březno u Chomutova has been chosen as a test site. We have progressed so that the geotechnical model of the geological environment above the tunnel was calculated first. The model was constructed on the base of two core wells, which were drilled near the tunnel especially for this purpose. The geotechnical model of deformation zone was converted into a density model and its gravity response was calculated. This model was compared with the gravity effect of the tunnel in rock environment without any deformation zone. The difference between effects of these two models gives the gravity response of the deformation zone. We found out that the gravity effect of the deformation zone is insignificant and does not affect the gravity interpretation in the environment of stiff tertiary clays, where the Březno tunnel is excavated. We compared the results of our modeling with the field gravimetric measurements results above the tunnel in Březno. The measurement was realized on three parallel profiles, which reach the tunnel in various depths. The results of...

Capillary flows continue to be important in numerous spacecraft systems where the effective magnitude of the gravity vector is approximately one millionth that of normal Earth gravity. Due to the free fall state of orbiting spacecraft, the effects of capillarity on the fluid systems onboard can dominate the fluid behavior over large length scales. In this research three investigations are pursued where the unique interplay between surface tension forces, wetting characteristics, and system geometry control the fluid behavior, whether in large systems aboard spacecraft, or micro-scale systems on Earth. First, efforts in support of two International Space Station (ISS) experiments are reported. A description of the development of a new NASA ground station at Portland State University is provided along with descriptions of astronaut training activities for the proper operation of four handheld experiments currently in orbit as part of the second iteration of the Capillary Flow Experiments (CFE-2). Concerning the latter, seven more vessels are expected to be launched to the ISS shortly. Analysis of the data alongside numerical simulations shows excellent agreement with theory, and a new intuitive method of viewing critical wetting angles and fluid bulk shift phenomena is offered. Secondly, during the CFE-2 space experiments, unplanned peripheral observations revealed that, on occasion, rapidly compressed air bubbles migrate along paths with vector components common to the residual acceleration onboard the ISS. Unexpectedly however, the migration velocities could be shown to be up to three orders of magnitude greater than the appropriate Stokes flow limit! Likely mechanisms are explored analytically and experimentally while citing prior theoretical works that may have anticipated such phenomena. Once properly understood, compressed bubble migration may be used as an elegant method for phase separation in spacecraft systems or microgravity-based materials manufacturing. Lastly, the stability of drops on surfaces is important in a variety of natural and industrial processes. So called 'wall-edge-vertex bound drops' (a.k.a. drops on blade tips or drops on leaf tips which they resemble) are explored using a numerical approach which applies the Surface Evolver algorithm through implementation of a new file layer and a multi-parameter sweep function. As part of a recently open sourced SE-FIT software, thousands of critical drop configurations are efficiently computed as functions of contact angle, blade edge vertex half-angle, and g-orientation. With the support of other graduate students, simple experiments are performed to benchmark the computations which are then correlated for ease of application. It is shown that sessile, pendant, and wall-edge bound drops are only limiting cases of the more generalized blade-bound drops, and that a ubiquitous 'dry leaf tip' is observed for a range of the critical geometric and wetting parameters.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19495号 / 理博第4155号 / 新制||理||1597(附属図書館) / 32531 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 福間 將文, 教授 川合 光, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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In this thesis, gravity and surface tension-driven water waves are investigated by designing an experimental setup to track wave patterns using a 300 fps high speed camera. This is done to reproduce the theoretical diagram of the dispersion relation for surface waves in different teaching contexts. Surface waves are dispersive, i.e. the phase speed depends on the wavelength.Initially, the background theory for surface waves is presented and the differences between gravity and surface tension-driven waves are described. The conditions for deep and shallow water are also studied. Thereafter, a literature study is conducted to study similar experiments. Test experiments are then carried out where both direct and indirect methods of observing the waves are examined to determine which method generates the best images.The water waves in the experiment are generated by dropping a 1.6 cm marble and a 4 mm water droplet into a 35 cm diameter hexagonal tank filled with 1–10 cm deep water. The waves are recorded from above and illuminated by backlighting with a 10 W LED panel. The experimental results show that a 1.6 cm marble generates wavelengths in the 0.4–3.5 cm range. Moreover, for a 4 mm water droplet, wavelengths in the range of 0.4–2.5 cm are generated.

One idea to stop the increasing threat of global warming is to build a space sunshade, made up of a constellation of satellites to reflect a portion of the sunlight. These satellites need to reach an equilibrium point where they can stay in orbit with minimal adjustments. A few feasibility studies have been made in this area and the location of the equilibrium point, L1' has been found. An area that is still unclear is the best way of getting the satellites to L1'. One idea is to use electric propulsion engines , and utilizing a gravity assist around the Moon on the way to L1'. Gravity assists have mostly been performed with chemical rocket engines, so doing it with electric propulsion causes some unique issues. The goal was to find a trajectory including the gravity assist showing that this could be an effective way of transporting the satellites. To measure how effective this would be, a trajectory without a gravity assist was also created as a means of comparison. The trajectory and orbit simulations were done in the program General Missions Analysis Tool (GMAT), and the resulting trajectory took 51 days and used 83.4kg of fuel for a fuel-to-mass-ratio of 21.5%. This was a worse result compared to the trajectory without a gravity assist, which only used 80.4kg of fuel. Finally a discussion around a potential trajectory which was shown to have a much greater velocity increase was had, which would indicate that a gravity assist maneuver could provide a trajectory that does save on fuel compared to using no gravity assist.

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<p><strong>Airborne gravity gradiometry (AGG) is a relatively new technology to the mineral exploration industry which has been increasingly used over the past decade. AGG systems are capable of separating linear accelerations due to aircraft movement from the accelerations related that represent the gravity signal, resulting in a much higher resolution measurement than airborne gravity. The rapid and cost-effective deployment of an AGG survey gives it an advantage when compared to traditional ground gravity survey. With the momentum of existing AGG technology in the exploration industry and the multitude of next-generation AGG sensors currently in development the technique promises to be a valuable exploration tool for the foreseeable future. This thesis focuses on the capabilities of the AGG technology as an exploration tool, its niche within the exploration process, and how AGG compares to other gravity methods. An overview of the AGG method provides context for the aim of the study. A history of airborne gravimetry is presented, as well as a detailed technical description of AGG measurements and units. A summary of all existing airborne gravity and airborne gravity gradiometry technology is provided, along with the major research initiatives aimed at making more sensitive AGG sensors in the future. A discussion of the potential sources of error and uncertainty when working with AGG data highlights many of the technique’s obstacles that we will be closely examining within this study. The AGG case study which is examined includes an AGG dataset collected as part of a nickel exploration program to image prospective troctolite chambers in Northern Labrador, by Vale. The study focuses on the portion of the survey over the Voisey’s Bay main block that contains several economic nickel deposits, including the world-class Ovoid deposit. This area has been characterized both geologically and geophysically in the past, and contains multiple datasets, including ground gravity. Forward modeling is completed using Voisey’s Bay physical rock properties to calculate the response that could be expected over a nickel-bearing troctolite chamber. The methodology and considerations of AGG data acquisition are reviewed in the context of this survey and the dataset is then taken through a terrain correction involving the determination of the best possible background density choice. The limitations and potential pitfalls of the terrain correction are examined in relation to the digital elevation model being used. The problem of thick, variable overburden in portions of the survey is also examined. Several filtering techniques are completed on the data, including vertical integration and the removal of the regional signal. The AGG resolution is then quantitatively compared to the historical ground gravity data and an upward continued version of the ground gravity (representing the response of an airborne gravity survey) by using 2D power spectra and radially averaged power spectra plots. Although the ground gravity is found to contain better resolution in some areas due to its proximity to the ground, the more regular spatial sampling of the AGG survey provided resolution advantages in other areas. The much higher sensitivity of the AGG sensor resulted in a strong resolution advantage over the upward continued gravity. This comparison is extended to include the differences in interpretive products produced from each dataset, in the form of 3D gravity inversions. Inversions were completed on all three datasets and the results are compared. Although the resolution of an individual ground gravity measurement is greater than that of an AGG measurement, the uniformity of the AGG survey provides superior coverage and leads to a more detailed inversion model, particularly for features greater than ~200-400m, such as the prospective nickel bearing troctolite chambers. </strong></p> / Master of Science (MSc)