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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Non-Invasive Methods To Detect Underground Leaks

January 2019 (has links)
abstract: Water is one of, if not the most valuable natural resource but extremely challenging to manage. According to old research in the field, many Water Distribution Systems (WDSs) around the world lose above 40 percent of clean water pumped into the distribution system because of unfortune leaks before the water gets anywhere from the fresh water resources. By reducing the amount of water leaked, distribution system managers can reduce the amount of money, resources, and energy wasted on finding and repairing the leaks, and then producing and pumping water, increase system reliability and more easily satisfy present and future needs of all consumers. But having access to this information pre-amatively and sufficiently can be complex and time taking. For large companies like SRP who are moving tonnes of water from various water bodies around phoenix area, it is even more crucial to efficiently locate and characterize the leaks. And phoenix being a busy city, it is not easy to go start digging everywhere, whenever a loss in pressure is reported at the destination. Keeping this in mind, non-invasive methods to geo-physically work on it needs attention. There is a lot of potential in this field of work to even help with environmental crisis as this helps in places where water theft is big and is conducted through leaks in the distribution system. Methods like Acoustic sensing and ground penetrating radars have shown good results, and the work done in this thesis helps us realise the limitations and extents to which they can be used in the phoenix are. The concrete pipes used by SRP are would not be able to generate enough acoustic signals to be affectively picked up by a hydrophone at the opening, so the GPR would be helpful in finding the initial location of the leak, as the water around the leak would make the sand wet and hence show a clear difference on the GPR. After that the frequency spectrum can be checked around that point which would show difference from another where we know a leak is not present. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019
232

The Kaskaskia-Absaroka Boundary in the Subsurface of Athens County, Ohio

Stobart, Ryan Patrick January 2019 (has links)
No description available.
233

Seasonal to Multidecadal Drivers of Variability at Greenland Outlet Glaciers

King, Michalea Dianne January 2020 (has links)
No description available.
234

Design and construction of a mobile equipment for thermal response test in borehole heat exchangers

Kamarad, Anthony January 2012 (has links)
In 2010, the Ground Source Heat Pumps (GSHPs) market in the European Union went up over one million (1 014 436 units at the end of 2010 according to EUROBSERV’ER 2011). In 2011, it was estimated around 1.25 million according to Bayer et al. (2012). With more than 378 000 units installed in 2010, according to the Swedish heat pump association (SVEP), the Swedish GSHPs market was the first in the EU. As for the French GSHPs market, it was estimated to 151 938 units in service in 2010, which propelled France at the third rank in the EU. However, despite a relatively important number of GSHPs installed in the whole EU, since 2008 GSHP sales have shrank. Even Sweden which has been the most competitive country sees its GSHP sales decline in the first quarter of 2012 (EUROBSERV’ER 2011). This report is the achievement of my Master of Science Thesis project. It also represents the end of my studies at INSA Lyon in France and concludes my degree in Energetic and Environment Engineering. This report deals with the improvement of a heat injection apparatus which is available at KTH (Royal Institute of Technology). This equipment is better known as Thermal Response Test (TRT) apparatus. This kind of equipment improves Borehole Heat Exchangers (BHE) design in terms of size and cost benefits. This technology is generally used to design GSHP installations in both domestic and industrial purposes. It allows to determine really important thermal BHE parameters: the thermal conductivity of the ground and the borehole thermal resistance. The report covers a theoretical description of TRT experiments, the reasons and objectives of such a project, the apparatus design and its construction. The last part is dedicated to a first experimental laboratory results and some problems met during the project course.
235

Resistivity and Radar Images of Collapse Features Attributed to a Previously Undocumented Shallow Coal Mine in Summit County, Ohio

Warino, Charles T. January 2008 (has links)
No description available.
236

Undifferenced GPS for Deformation Monitoring

Andersson, Johan Vium January 2006 (has links)
This thesis contains the development of a deformation monitoring software based on undifferenced GPS observations. Software like this can be used in alarm systems placed in areas where the earth is unstable. Systems like this can be used in areas where people are in risk of getting hurt, like in earthquake zones or in land slide areas, but they can also be useful when monitoring the movements in buildings, bridges and other artefacts. The main hypotheses that are tested are whether it is possible to detect deformations with undifferenced observations and if it is possible to reach the same accuracy in this mode as when working in a traditional mode where the observations are differenced. The development of a deformation monitoring software based on undifferenced GPS observations is presented. A complete mathematical model is given as well as implementation details. The software is developed in Matlab together with a GPS observation simulator. The simulator is mainly used for debugging purposes. The developed software is tested with both simulated and real observations. Results from tests with simulated observations show that it is possible to detect deformations in the order of a few millimetres with the software. Calculations with real observations give the same results. Further, the result from calculations in static mode indicates that the commercial software and the undifferenced software diverge a few millimetres, which probably depends on different implementations of the tropospheric corrections. In kinematic mode the standard deviation is about 1 millimetre larger in the undifferenced mode than in the double differenced mode. An initial test with different observation weighting procedures indicates that there is a lot of potential to improve the result by applying correct weights to the observations. This is one of the aims in the future work within this project. This thesis are sponsored by the Swedish Research Council for Enviroment, Agricultural Sciences and Spatial Planning, FORMAS within the framework “Monitoring of construction and detection of movements by GPS ref no. 2002-1257" / QC 20101108
237

Spatial Assessment of Soil Contamination through GIS Data Management

Sjödell, Ingrid January 2018 (has links)
Spatial data management within the environmental field has a large range of application possibilities and comes with great advantages. In this study methods and technologies for spatial data management of soil contamination has been assessed in Geographical Information Systems (GIS), in order to identify in which way spatial data applications and tools can contribute with valuable information for these type of projects. The spatial assessment has been applied on a case study site in Kagghamra, Stockholm, exposed to high levels of contaminants, arsenic in particular. Subjects that have been evaluated are arsenic contamination distribution pattern, estimation of volume contaminated soil and amount of samples needed for spatial analyses. Furthermore, two versions of an exploratory soil sensitivity estimation model based on site specific ground and landscape parameters as well as literature references have been developed. The data management included large quantities of primary and secondary data of the commination levels as well as geological and ground properties. First hand collected geophysical field data obtained from Electromagnetic (EM) and Induced Polarisation (IP) measurements was also interpreted. The benefits of using geophysical measurements in soil contamination projects has been investigated. In this case the benefits were few due to difficult measuring conditions with disturbance noise. Spatial interpolations with the Natural Neighbour  (NN) technique are proven to be useful in transforming point contamination data into continuous layers. From the interpolation surfaces (arsenic distribution map) a variety of information can be extracted, such as a first hand volume estimation of contaminated soil, possibilities of reduction in amount of field sampling or to investigate statistical information and relations to different site specific ground conditions. The soil sensitivity estimation models are combined maps consisting of data layers that are relevant for the arsenic behaviour and interaction in the subsurface. Site specific Model (1) is based the data layers Soil type, Iron level, Soil depth, Slope  and illustrates mainly areas exposed to high concentrations of arsenic as high sensitivity areas. The more general, literature supported Model (2) also includes Vegetation cover and Topographic Wetness Index (TWI) and is not related highly to the arsenic distribution in the site area, but could contribute with general implications of sensitive areas if applied on a another, larger site area. Efficient management of large data quantities, economic and time saving benefits from less physical sampling and good representation and visualisation possibilities of the site conditions, as a tool for stakeholder communication and decision-making are the main contributions from the spatial data management.
238

Detecting Submerged Remains: Controlled Research Using Side-scan Sonar To Detect Proxy Cadavers

Healy, Carrie 01 January 2012 (has links)
While side-scan sonar has become a valuable geophysical tool for forensic water searches, controlled research is paramount to determine the best practices for searches in aquatic environments as it provides a structured environment in which to investigate variables that influence the effectiveness of the technology and provides valuable experience for sonar operators. The purpose of this research is to conduct controlled research in order to evaluate the applicability of side-scan sonar to searches involving submerged firearms and proxy cadavers. In addition, the best practices for employing this technology in forensic searches in freshwater ponds and lakes in a humid, subtropical environment in Central Florida would be developed. Five street-level firearms were submerged in a pond, and two sets of three pig carcasses (Sus scrofa), utilized as proxies for human bodies, were staked to the bottom of a pond for this research. Transects were conducted over the firearms and the pig carcasses utilizing side-scan sonar. The first set of pig carcasses represented a child size (30-32 kg) and the second set a small adult size (51-54 kg). Results show that firearms were not detected due to the terrain and small size. However, this technology successfully located small to medium-sized proxy carcasses on a flat, sandy lake bottom when experienced operators were conducting the search. Conversely, vegetation obscured submerged bodies. While the smaller carcasses were difficult to detect throughout the data collection, medium-sized carcasses were easily discerned. Moreover, the medium-sized carcasses decomposed at the same rate as previous studies and were visible throughout each stage of decomposition. Finally, employing a 900 kHz frequency with a 20 m swath-width provided the best search parameters. Therefore, in the appropriate conditions, iv side-scan sonar is an effective tool for locating submerged bodies in freshwater lakes and ponds in a humid, subtropical environment.
239

Detecting Buried Metallic Weapons In A Controlled Setting Using A Conductivity Meter And A Ground-penetrating Radar

Dionne, Charles 01 January 2009 (has links)
Searching for buried metallic evidence at crime scenes or at potential disposal sites can be a daunting task for forensic personnel. In particular, it is common to search for a small firearm that was discarded or buried by the perpetrator. When performing forensic searches, it is recommended to first use non-invasive methods such as geophysical instruments to minimize damage to evidence and to the crime scene. Geophysical tools are used to pinpoint small areas of interest across a scene that will be invasively tested later. Prior to this project, there was no published research that tested the utility of the conductivity meter to search for metallic weapons such as firearms and blunt or sharp edged weapons. A sample comprised of 32 metallic weapons was buried in a controlled setting to test the applicability of a conductivity meter for forensic searches. Weapons were tested at multiple depths; once data collection was performed for one depth, the weapons were reburied 5cm deeper until they were no longer detected. Results obtained with conductivity meter were compared to results obtained by the ground-penetrating radar using different depths and transect intervals. The effects of several variables on detection such as weapon size, metallic composition, burial depth, and transect interval were analyzed in order to explore the limitations of each instrument. Results obtained from this controlled research can provide guidelines to help law enforcement in real-world searches.
240

ASCAT Wind Estimation at 2.5 km Resolution Supported by Machine Learning Rain Detection

Kjar, Joshua Benjamin 01 December 2022 (has links)
The Advanced Scatterometer (ASCAT) is a C-band scatterometer designed to be less sensitive to rain contamination than other higher frequency scatterometers. However, the radar backscatter is still affected by rain which increases error during wind estimation. The error can be reduced in rainy conditions by combining a rain backscatter model with the existing wind only (WO) backscatter model to perform simultaneous wind and rain (SWR) estimation. I derive and test several 2.5 km resolution rain backscatter models for ASCAT data which are used with the WO model to estimate the near surface winds. Various rain models optimal for different purposes are discussed. The best rain model for estimating wind speed lowers the root mean square error (RMSE) in the presence of rain by 13.6% when compared to using the WO model alone. The rain model which best predicts rain rates has a RMSE of 7.9 mm/h. A neural network (NN) is designed to discriminate the presence of rain using ASCAT's backscatter measurements. Such a NN enables the SWR algorithm to be used only on rainy samples and thus improves estimation. By removing all samples identified by the NN as rain, the WO algorithm's speed estimate improved by 2.83%.

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