Examensarbeten för masterexamen // Master Theses
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- PostCAN Sample-Point Analyzer(2011) Carlsson, Mathias; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThe purpose of this master thesis project is to develop a method for verifying the sample point position (SPP) of an electronic control unit (ECU). The thesis is performed in two phases; first a theoretical solution of the problem and also a practical implementation. To realize the theory a circuit board were constructed. The solution of the problem is then tested and verified on the design PCB. To be able to validate the test result special test instrument was used such as an oscilloscope with a controller-‐‑area network (CAN) analyzer module. To analyse the sample point position the method used takes advantage of the built-‐‑in error detection function, Stuff error. The Stuff error is a mechanism integrated in the CAN protocol and is provoked when it don’t perceive an expected stuff bit in the message sent over the CAN bus. To generate a stuff bit error the bit length of the stuff bit is decreased until the receiver no longer can interpret it. When this occurs an error flag is set and by keeping track of the number of steps that the length has been decreased the sample point position can be calculated. The accuracy of the calculation of the sample point position is within the given limits that have been set for this project. As seen in the report the results are SPP±2% which is close enough to know when data is sampled.
- PostCapturing radon on tobacco smoke(2011) Sanden, Magnus; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceRadon is one of the largest causes for lung cancer in the world. In fact, it is second only to smoking. It has been observed that tobacco smoking increases the risks of radon-induced lung cancer, but there does not appear to be any theory that quantitatively describes why this is. This thesis is a study of a possible reason for this increase in mortality. I have investigated if and how radon atoms adsorb onto some molecules present in tobacco smoke and other types of smoke. My study can therefore also help to develop an understanding of possible radon-associated health effects that may follow from enjoying an open replace. If radon does adsorb onto the smoke it may increase the likelihood of these radioactive atoms decaying in the lungs and depositing their daughter nuclei there. Most of the daughter nuclei are radioactive and of them at least lead is also toxic. The investigation was done through electronic structure calculations using density functional theory. I have chosen a non-empirical method because there are not many experiments on radon interactions. The van der Waals density functional was used to account for the van der Waals interactions. Adsorbtions of between 70 meV and 156 meV were found on all investigated molecules from the smoke. Large polycyclic aromatic hydrocarbons gave the strongest adsorbtion. In a trend study with different noble gas atoms, bigger atoms adsorbed more strongly, including radon which adsorbed most strongly. The thesis includes an overview of the theory behind the density functional theory used in the calculations.
- PostHigh speed communication(2010) Legeza, Robert; Bodin, Johan; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThis master thesis examines the problems that occur for high speed serial communication. The thesis focus on serial transmission through backplane, coaxial cable and optical fiber. Experiments using RocketIOTM GTP and GTX transceivers are performed at data rates of up to 5 Gbit/s. Measurements are done using integrated bit error rate tester (IBERT), network analyzer and time domain reflectometer. The thesis presents methods to evaluate the transmission quality based on IBERT measurements. The methods uses data from measurements to evaluate performance and estimate BER of the link. Impact on BER from effects such as temperature and attenuation is examined and techniques to strengthen the signal integrity is evaluated in this thesis. The basics of a pulse shaping filter is also proposed.
- PostHow Anode Porosity a ects the performance of a Solid Oxide Fuel Cell(2014) Billemar, Jakob; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThe purpose of this project was to investigate how parameters, such as size of zirconia particles and the porosity, impact the performance of the anode of a solid oxide fuel cell. The analysis that has been conducted was focused on investigating SEM-pictures and analysing electrochemical impedance spec- troscopy(EIS) measurements on half-cells. The data suggest that an increasing porosity lead to an almost linear increase of TPBs/area in the range of 20- 40%. From the results, it was not obvious that the amount of triple phase boundaries(TPBs) was dependent on the size of the zirconia particles in the range between 0.12 and 1m. The EIS measurements suggest that the activation energy resulting from the first arc decreased as more measurements were done, at least for the sam- ple named Red. half-cell. This effect could be within the margin of errors, and hence just a coincidence. It could also be seen that the sample with the thickest electrolyte gave rise to the highest impedance, but not a much higher activation energy than the other reduced samples. Furthermore there appear to be a difference in shape between reduced and not reduced samples, and a substantial differences regarding activation energy and conductivity could also be seen.
- PostHydrogen adsorption on graphene and coronene: A van der Waals density functional study(2011) Varenius, Eskil; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThis thesis investigates hydrogen adsorption on graphene and coronene within the framework of density functional theory. The new nonlocal van der Waals density functional (vdW-DF) method is used: the original version, vdW-DF1, and the new higher accuracy version, vdW-DF2. Hydrogen adsorption is studied in the context of formation of molecular hydrogen in interstellar space, a process thought to depend on hydrogen adsorbing on a graphitic surface. Calculations were done for hydrogen above coronene and graphene with both vdW-DF1 and vdW-DF2 to investigate how these functionals perform in the case of hydrogen adsorption on a graphitic surface. All calculations were performed with the software GPAW in a non-self consistent way based on underlying selfconsistent GGA (revPBE) calculations.The calculations performed in this thesis indicate that it is important to use a spin-polarised description of the physics to get accurate results for hydrogen adsorption on a graphitic surface.
- PostPhoton generation in a doubly tunable resonator(2012) Svensson, Ida-Maria; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceIn November 2011 the first experimental observation of the dynamical Casimir effect was published [1]. Superconducting circuits were used to show that a single mirror moving in vacuum could generate photons, by parametric amplification of vacuum uctuations. This project is a side track of this research where a second mirror is introduced to investigate photon generation in-between the mirrors. The work includes both theory studies and experimental practice. Resonators have been fabricated on chip in a cleanroom and measured in a dilution refrigerator. The focus has been on how the different boundary conditions of the resonator field affect the photon generation. A superconducting circuit has been used including a = 2/2 resonator with two SQUIDs inducing tunability of the resonance frequency via on-chip ux tuning lines. The two SQUIDs are placed in each end of the cavity in order to simulate moving mirrors. The mirrors are used to modulate the boundary conditions of the cavity. This is done by changing the SQUID inductance which is achieved by applying a magnetic ux to the SQUID loop. Depending on if the mirrors move in or out of phase, a breathing or translational mode can be created in the cavity. Theory predicts photon generation in different modes depending on if the pump frequency is two or three times the resonance frequency [2]. Measurements have been done at a temperature of around 50mK, which is low enough to have a negligible amount of thermal photons and quasi-particles in the cavity. The static tuning of the resonator have been probed by sweeping the uxes applied to the two SQUIDs and at each point the resonance frequency has been extracted. Good results have been achieved and two dimensional tuning is shown. A high frequency, ux modulation have been applied to the SQUIDs both one at a time and simultaneously to generate photons. In the two mirror modulation case qualitative agreement with theory has been observed for driving in the breathing and translational mode respectively. Generation occurs first for the breathing mode at 2*omega (twice the resonance frequency) and for the translational mode at 3*omega.
- PostQuantum non-demolition detection of propagating microwave photons(2012) Sathyamoorthy, Sankar Raman; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceTypical photon counters involve absorption of photons to generate electric signals, thus basically destroying the information carried by the photon. This is all the more disastrous if the photon is used as a quantum information carrier, such as a part of an entangled pair. Quantum non-demolition (QND) measurements are de- signed to overcome this limitation. Such a non-destructive photon detection would play a key role in quantum networks where photons can be used as “flying” qubits. In this thesis, using circuit QED we investigate if QND detection of a prop- agating microwave photon is possible. The system considered consists of a three level artificial atom (transmon) interacting with signal and probe fields. The fields are in the microwave regime with their frequencies on par with the energy levels of the transmon. The interaction of these two fields with the artificial atom, imparts a phase change on the probe field via the cross-Kerr effect. By measuring this phase change, we indirectly infer the presence of the signal. In this thesis, we investigate if it is possible to achieve a single photon detection, at first using a single transmon and then using multiple transmons. We find that, while single photon detection is not possible with a single transmon, it is indeed possible with multiple transmons under certain conditions. We also find that with multiple transmons, we can have a large phase change in the probe, which might be desirable in other applications.
- PostSub-millimetre wave imaging(2011) Dahlbäck, Robin; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThe sub-millimetre wave region withholds many interesting properties that can be used for imaging. Common packaging materials are transparent making package inspection possible without the use of ionising radiation. Contrast can also be seen between healthy and diseased tissue for some common forms of cancer. Many other biomedical applications are still un- explored making it an interesting research topic. A study of common system topologies are presented together with an imaging system built with in-house components. The imaging system is adopted for the use of a microwave to- mography image reconstruction algorithm. System characterisation data are presented, the usable bandwidth is 6.5 % centred around 337 GHz. Mea- surement repeatability and long therm stability is also evaluated, concluding that the system most likely is good enough for use with the image recon- struction algorithm. Furthermore test images are presented.
- PostTunneling into a Heavy Fermion System(2012) Spånslätt, Christian; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceThe discovery of an extremely high effective electron mass in CeAl3 by Andres et al in 1975 was the starting point for Heavy Fermion physics. One possible theory for explaining this heavy fermion behaviour is the Kondo lattice model which is investigated in this master thesis. With a slave boson mean field approach using Green’s functions, a set of mean field equations are derived and solved. The solutions of these equations determine the model behaviour as a function of various input parameters. In addition, a system where the Kondo lattice model is in close proximity to a Scanning Tunneling Microscope is considered. By the use of non-equilibrium Keldysh formalism, a tunneling current and differential conductance is calculated. The differential conductance is seen to map out the Kondo lattice density of states.