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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.
1

Using Python language for analysing measurements from SABER instrument on TIMED satellite

Hoffmann, Peter, Jacobi, Christoph, Gimeno-Garcia, Sebastian 27 September 2017 (has links)
The practical handling and analysis of satellite data is outlined using the programming language Python. The limb sounding technique of the SABER instrument on board of the TIMED satellite delivers vertical profiles of kinematic temperature from the stratosphere (∼30 km) up to the lower thermosphere (∼120 km). The procedure may be summarised as follow: In the first step the level 2 data for one month are extracted from the netCDF format and arranged into a new altitude-latitude grid for the ascending and descending orbits. The longitudinal structure is rearranged applying the decomposition into zonal harmonics. Various cross sections of the data give a good overview of the thermal structure and dynamics of the atmosphere up to 120 km. The monthly values of the zonal averaged temperature are compared to the available data from stratospheric reanalyses up to 60 km as well as the initialized background climatology of general circulation models for the middle atmosphere. / In diesem Artikel soll der praktische Umgang mit Satellitendaten und deren Auswertung unter Verwendung der Programmiersprache Python skizziert werden. Auf der Basis der Horizontsondierungen des SABER Instruments auf dem TIMED Satelliten werden vertikale Profile wie die kinetischen Temperatur von der Stratosphäre (∼30 km) bis zur unteren Thermosphäre (∼120 km) gewonnen. Die Arbeitsschritte bei der Analyse lassen sich wie folgt gliedern: Als erstes werden die Level 2 Produkte eines Monats aus dem netCDF Format extrahiert und an ein neues Höhen-Breiten Gitter für jeden auf- und absteigenden Orbit angepasst. Die Längenstruktur wird mit Hilfe einer Zerlegung in harmonische Funktionen regularisiert. Diverse Querschnitte der Daten geben ein guten Überblick über die thermischen Struktur und Dynamik der Atmosphäre bis 120 km. Die Monatswerte des Zonalmittels der Temperatur werden mit denen aus operationellen Reanalysedaten (∼60 km) sowie der Hintergrundklimatologie von Zirkulationsmodellen der mittleren Atmosphäre verglichen.
2

Using radar for monitoring lab rats: Data analysis and radar parameter tuning for rats

Sörgård Svenning, Jörgen January 2019 (has links)
I April 2018 an experiment was conducted at the university of Bergen in collaboration with Novelda using the XeThru range-doppler radar. The goal of the experiment was to record data on rats using XeThru radar and by using traditional medical sensors, to see if a XeThru radar can be used instead of the traditional sensors. The data from the experiment consisted of data saved as EDF (European Data Format) from the traditional sensors, radar data and video. The rest goal of this thesis was to analyze the different data types. Then to look at the radar data with the goal of seeing if respiration detection on rats was possible and try to create a radar pro le for use on rats. This report focuses on only one of the rats from the experiment, because this rat was recorded using a video camera. In a preliminary project a python program had been written to use on the EDF data. The program was expanded upon in this thesis to optimize the performance. The python program took the EDF data and extracted the desired signal, data from a muscle sensor, and plotted it, making it possible to analyze. For the radar data Matlab was used, since Novelda already had the tools to process the data using that program. This worked using parameter les to set all the necessary settings to do a playback and change the radar and processing settings. The work then consisted of changing the parameters to get the best results on the data from the rats. A parameter le was created for use on rats that was based on the parameter le for respiration detection on adult humans. The conclusion on the EDF data was that it was not possible to nd a pattern for respiration using the muscle sensor. The radar data fortunately yielded better results. After much testing and optimization it was possible to get good respiration detection on rat 7. Some of the e ndings was possible noise problems and sources. The radar was mounted to the rack holding the cages. This meant it was susceptible to vibration noise form the other rats in the same rack and to the construction work being done at the university. Another problem with mounting of the radar was that is was to close to the cage, because the rat slept close to the wall of the cage closest to the radar. Then the problem of directly coupled energy interfered with the actual signal form the radar. It is still unclear if a radar sensor can replace the traditional sensors, but it is very possible to detect respiration on rats. With some more work, and possible a new experiment xing the noise sources, can make it possible.
3

Size effect in wood : Characterization of mechanical properties using digital image correlation method

Saeidi, Amir, Johannsson, Olafur January 2023 (has links)
As a natural composite material, wood exhibits complex structural char-acteristics and diverse behavior under compression and tensile forces. Itsanisotropic nature results in mechanical properties that vary depending onthe load direction along its longitudinal, tangential, and radial grains. An im-portant property of anisotropic materials is the modulus of elasticity, whichrelates stress to strain and demonstrates directional variations.This study focuses on investigating the mechanical properties of pinewood,particularly stiffness, and deformation, in the longitudinal direction duringcompression, taking into account the effect of the sample size. The digitalimage correlation (DIC) method is utilized to measure deformation, an op-tical technique that involves tracking motion in DIC patterns. Wood, beinga renewable and natural composite resource, has been widely used as a con-struction material and for various other purposes for centuries. Its physicaland mechanical properties encompass a broad spectrum influenced by factorssuch as species, moisture content, density, and temperature.This research aims to analyze the size-dependent effects on deformation andstiffness in pine wood samples using the DIC method. Initially, three sam-ple sizes were compared, namely 10 × 10 × 10mm3, 20 × 20 × 20mm3, and25 × 25 × 100mm3 these were selected based on Afshar (2022) and Walley& Rogers (2022). However, the sample size of 20 × 20 × 20mm3 producedinsufficient results due to equipment limitations to test them under sufficientload. Among the remaining sample groups, nine specimens from each groupwere tested and compared in terms of stiffness and deformation. The exper-imental results did not provide statistically significant data supporting thepresence of a noticeable size effect between the dimensions of the samples10 × 10 × 10mm3 and 25 × 25 × 100mm3. / Trä är ett förnybart och naturligt kompositmaterial och har i århundradenanvänts som byggmaterial och för olika ändamål. Dess fysikaliska och mekaniskaegenskaper omfattar ett brett spektrum som påverkas av faktorer som fuk-thalt, densitet och temperatur. Trä som ett naturligt kompositmaterial ochdess komplexa strukturella egenskaper visar varierande beteende vid tryckoch dragkrafter. Träets anisotropa natur gör att dess mekaniska egenskapervarierar beroende på belastningsriktning, längs dess längd, tangential ellerradial riktning. För anisotropa material är elasticitetsmodulen en viktig egen-skap som varierar längs de olika riktningarna. Vilket är ett samband mellanspänning och deformationen och visar riktningsvariationer.Den här studien syftar till att undersöka de mekaniska egenskaper hos furu.Den här studien undersöker storleks-effekt i materialet furus styvhet och de-formationen längs fiberriktning (längd) vid kompression med hjälp av DigitalImage Correlation (DIC). Metoden DIC är en optisk teknik som mäter de-formationen hos material med hjälp av spårningsmönster på materialet.För att se storleks effekten hos trä jämfördes initiellt tre provstorlekar, näm-ligen 10 × 10 × 10mm3, 20 × 20 × 20mm3, och 25 × 25 × 100mm3 dessa provs-torlekar valdes baserat på Afshar (2022) och Walley & Rogers (2022). Dockproducerade provstorleken 20 × 20 × 20mm3 otillräckliga resultat på grundav begränsningar i utrustningen för att testa dem under tillräcklig belast-ning. Bland de återstående provgrupperna testades och jämfördes nio provfrån varje grupp när det gäller styvhet och deformation. De experimentellaresultaten gav inte statistiskt signifikanta data som stödjer förekomsten aven märkbar storlekseffekt mellan dimensionerna hos proven 10 × 10 × 10mm3och 25 × 25 × 100mm3.

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