This thesis gives a short introduction into the higher gauge algebras. We first in- troduce the BRST formalism in the context of ordinary gauge theories and show the properties that allow us to use it in the context of higher gauge theories. We define the 2-groups and show the correspondence between 2-groups and crossed modules. We then give a brief introduction into the theory of L∞-algebras - we give account of the graded manifolds and Q-manifolds. We give a short account of Homotopy Maurer-Cartan theory and show that it reduces to the BF theory in case of 4-dimensional manifold and 2-term L∞-algebra. 1

The competition in the car market in the world is continuously intensifying. To gain an advantage in the market while making a profit, each car manufacturer needs a strong focus on always improving in the technology development. It is not just technology of the cars that need development, but it is equally important to improve the manufacturing processes itself. In the end, this will result in more appealing products for the customer at a competitive cost. The aim and scope of this master thesis is to get a deeper understanding of the forces in the stamping die during sheet metal forming in manufacturing. By using strain gauges and microcontrollers, the forces during the entire forming process could be measured and analyzed. The relationship between the force on the pressure pins in the die and the length of the pressure pins was also investigated by adding shims on the pressure pins. A modular system using Arduino Uno with 3D-printed parts was developed to measure the forces in the blank holder during sheet metal forming. An Arduino software system and TeraTerm was found the most appropriate for collecting and organizing data from the strain gauge sensors and microcontrollers. Tests were then conducted using different settings of the press, and these showed that the forces in the blank holder were uneven. Adding shims to the pins so that they were all of equal length evened out the forces in the blank holder. Another test showed that adding more shims to only one of the pins increased the force in that pin, and that adding 0.5mm of shims to that pin more than doubled the maximum force. The system developed in this thesis can measure the forces in the blank holder during the sheet forming process at a lower speed of production. This system can also detect different force settings in the press. Lastly, it can also detect a difference in force for different pressure pin lengths. / Konkurrensen på bilmarknaden i världen intensifieras kontinuerligt. För att få en fördel påmarknaden samtidigt som de gör vinst måste varje biltillverkare ha ett starkt fokus på att alltid förbättrateknikutvecklingen. Det är inte bara bilens teknik som behöver utvecklas, utan det är lika viktigt attförbättra tillverkningsprocesserna i sig. I slutändan kommer detta att resultera i mer attraktiva produkterför kunden till ett konkurrenskraftigt pris. Syftet och omfattningen av detta examensarbete är att få en djupare förståelse av krafterna ipressverktyget under plåtformningprocessen. Genom att använda töjningsgivare och mikrokontrollerkunde krafterna under hela formningsprocessen mätas och analyseras. Förhållandet mellan kraften påmothållarpinnarna i verktyget och längden på pinnarna undersöktes också genom att lägga till shims påpinnarna. Ett modulsystem som använde Arduino Uno med 3D-printade delar utvecklades för att mätakrafterna i formen under formningsprocessen. Ett Arduino-mjukvarusystem och TeraTerm bedömdesvara det mest lämpliga för att samla in och organisera data från töjningssensorer och mikrokontroller. Tester genomfördes sedan med olika inställningar i pressen, och dessa visade att krafterna ipressverktyget var ojämna. Genom att lägga till shims på pinnarna så att de alla var lika långa utjämnadeskrafterna i pressverktyget. Ett annat test visade att genom att lägga till fler shims på endast en avmothållarpinnarna ökade kraften i pinnen. Genom att tillägg till 0,5 mm shims på den pinnen mer änfördubblade den maximala kraften. Systemet som utvecklats i denna rapport kan mäta krafterna i pressverktygets mothållarpinnarunder formningsprocessen vid en lägre produktionshastighet. Detta system kan också upptäcka olikakraftinställningar i pressen. Slutligen kan den också upptäcka skillnader i kraft vid olika längder påmothållarpinnarna.

Nous avons investigué les propriétés des champs de jauge de spin élevé libres à travers une étude de divers aspects de leur dynamique hamiltonienne. Pour des champs se propageant sur un espace-temps plat, les contraintes issues de l'analyse hamiltonienne de ces théories de jauge ont été identifiées et résolues par l'introduction de prépotentiels, dont l'invariance de jauge comprend, de façon intrigante, à la fois des difféomorphismes linéarisés généralisés et des transformations d'échelle de Weyl généralisées et linéarisées. Cela a motivé notre étude systématique des invariants conformes pour les spins élevés. Les invariants correspondants ont été construits à l'aide du tenseur de Cotton, dont nous avons établi les propriétés essentielles (symétrie, conservation, trace nulle; invariance, complétude). Avec ces outils géométriques, l'analyse hamiltonienne a pu être complétée et une action du premier ordre écrite en termes des prépotentiels. Nous avons constaté que cette action possédait une invariance manifeste par dualité électromagnétique; cette invariance, combinée à l'invariance de jauge des prépotentiels, fixe d'ailleurs uniquement l'action. En outre, de façon générale, cette action s'est révélée être exactement celle obtenue à travers une réécriture des équations du mouvement des spins élevés comme des conditions d'auto-dualité tordue (non manifestement covariantes).Avec un intérêt pour les extensions supersymétriques, nous avons amorcé la généralisation de cette étude aux champs fermioniques. Le champ de masse nulle libre de spin 5/2 a été soumis à la même analyse, et son prépotentiel s'est révélé partager l'invariance de jauge conforme déjà observée dans le cas bosonique général. Le supermultiplet incorporant les spins 2 et 5/2 a ensuite été considéré, et une symétrie rigide de son action, combinant une transformation de dualité électromagnétique du spin 2 avec une transformation de chiralité du spin 5/2 a été construite pour commuter avec la supersymétrie. Dans une autre direction, nous avons étudié les propriétés d'un champ tensoriel chiral de symétrie mixte dans un espace-temps plat à six dimensions: une (2,2)-forme. Son analyse hamiltonienne a été réalisée, des prépotentiels introduits et l'action de premier ordre obtenue s'est encore une fois révélée être la même que celle obtenue à travers une réécriture des équations du mouvement comme des conditions d'auto-chiralité (non manifestement covariante).Finalement, nous nous sommes penchés sur les charges de surface des champs fermioniques et bosoniques de spin élevé se propageant sur un espace-temps à courbure constante. Cela a été réalisé par une analyse hamiltonienne de ces systèmes, les contraintes étant identifiées aux générateurs des transformations de jauge. Injectant dans ces générateurs des valeurs des paramètres des transformations de jauge correspondant à des transformations impropres de jauge (imposant une réelle variation physique sur les champs) a ensuite permis d'évaluer la valeur de ces générateurs pour des champs résolvant les équations du mouvement: elle s'est bien révélée finie et non-nulle, constituant les charges de surface de ces théories. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The N= 4 Super Yang-Mills theory in four dimensions admits deformations and the exactly marginal deformations of its SU(3) R-symmetry sub-sector are known as Leigh-Strassler. Leigh-Strassler deformations break the N= 4 supersymmetry down to N= 1 while preserving conformal symmetry. With exactly marginal deformations only the F-terms are deformed thus Leigh-Strassler deformations only affect the superpotential in the Lagrangian. In this thesis we study the symmetry of the marginally deformed N= 4 SYM and demonstrate that its algebraic structure can be understood in terms of quasi-Hopf algebras. Quasi-Hopf algebras have a notion of twisting due to Drinfeld which makes them a natural mathematical language with which to treat deformations. Furthermore the deformation of the N= 4 SYM superpotential is automated by the definition of a suitable star product. / Thesis (PhD)--University of Pretoria, 2020. / NiTheP / Physics / PhD / Unrestricted

Vid träning av baksida lår kan det vara svårt att förstå hur muskeln aktiveras. Genom att visualisera de myoelektriska signalerna från biceps femoris och semimembranosus till den som tränar kan personen få en bättre mind-muscle connection. I examensarbetet har två teoretiska EMG sensorer skapats och simulerats, kod har skrivits för att filtrera fyra EMG signaler samt överföra dessa över BLE, kraftsensorer är kopplade och kod är skriven för att avgöra den kraftutveckling som sker i en kontraktion av baksida lår. EMG sensorerna har jämförts med SparkFuns MyoWear muskelsensor, OpenBCI Cyton board och BioNomadix BN-EMG2-T. Båda de teoretiska lösningarna anses likvärdiga med ett billigare alternativ till Cryton Board, en flerkanalig lösning till MyoWear, BN-EMG2-T är för dyr att realistiskt implementeras till examensarbetets syfte. Simuleringarna visar att kretsarna behandlar signalen enligt tänkt sätt men det gick inte att bygga en prototyp då en pandemi har begränsat KTH:s verksamhet / One difficulty when training hamstrings is the understanding of how the muscle is activated. Through visualization of the myoelectrical signals from biceps femoris and semimembranosus to the exerciser, a better mind-muscle connection can be achieved. In this bachelor thesis, two theoretical EMG sensors were created and simulated, code to filter four EMG signals and transmit them through BLE was written, also a way to calculate how much force is applied in a hamstring curl was constructed. Both EMG sensors have been compared against SparkFuns MyoWear muscle sensor, OpenBCI Cyton Board and BioNOmadix BN-EMG2-T. The theoretical EMG sensors are interconvertible to a cheaper Cyton Board, a multichannel alternative to MyoWear, the BN-EMG2-T is too expensive to be a realistic alternative for this bachelor thesis attended purpose. Simulations show that the EMG sensors behave as intended but because of a pandemic, a prototype could not be created.

Additive manufacturing (AM) also commonly known as 3D-printing is a manufacturing method which creates parts from adding layer into another. In the field of printed electronics Inkjet printing (IJP) and Aerosol Jet printing (AJP) are the most common AM techniques. IJP and AJP are non-contact-based printing techniques where ink is deposited on a surface with droplets. AJP aerosolizes the ink into a mist which is deposited on a surface according to the predetermined pattern. IJP instead produces singular droplets when printing. These printing methods have been used for manufacturing various printed electronics such as strain gauges which has been the focus of this project.  The purpose of this thesis was to investigate the feasibility of printing strain gauges. Through a literature study the overall function and use for strain gauges and various printing methods were investigated, as well as previous studies related to printed strain gauges using AJP and IJP. To further investigate one of these techniques, strain gauges were printed using Inkjet printing. The sensors were printed using two different inks, one containing silver particles and the other containing constantan particles. The strain gauges were also printed on various substrates such as Polyimide (PI) and Polyetheretherketone (PEEK), to determine the best material combination. The silver strain gauges were then sintered in an oven while the constantan sensors were sintered using photonic sintering. To evaluate each ink-substrate combination several tests was performed throughout the printing and sintering process. A tape test was used to determine adhesion, SEM analysis was performed to study the effect of the sintering process and the resistance was measured to calculate the conductivity and study the printability on different substrates. To characterise the printed strain gauges a bending test was performed where the change in resistance was measured with changing strain. The output was also studied over time to determine the stability of the printed sensors.  The silver ink showed overall better properties compared to the constantan ink, which could be due to that the silver ink has been more developed than the constantan ink. The resistivity of the silver ink was calculated to 7.0E-07 Ωm and the constantan ink to 2.23E-05 Ωm. The average gauge factor for the silver ink printed on PI was calculated to GFavg~1.6 at low strain and GFavg~2.1 at high strain, the silver samples printed on PEEK was GFavg~2.4 at low strain and GFavg~2.3 at higher strain, and the constantan samples was determined to GFavg~2.7 during loading at low strain and GFavg~17 at high strain due to deformation. Some of the samples printed with silver ink showed quite linear behaviour while the samples printed with constantan deformed when applying high stress. The silver samples printed on PEEK showed more hysteresis compared to the silver samples printed on PI, but the PEEK samples showed a better stability over time compared to PI.  The thesis shows that it is possible to manufacture strain gauges, but the result depends a lot on the ink and substrate material chosen. Silver inks has been developed over a long period and thus making it easier to handle and the result is better compared to newer inks such as constantan.

Debris flows occur frequently in remote areas of Great Smoky Mountains National Park, Tennessee. Rainfall gauges are not adequate for modeling infiltration required for triggering debris flows. Weather radar, providing frequently updated, continuous coverage, is a valuable tool for estimating rainfall intensity, duration, runoff, and infiltration. Daily rainfall from a sole gauge was compared with hourly rainfall from the Digital Precipitation Array weather radar product to model infiltration on August 5, 2012, the day before a debris flow was known to have occurred in the 91-km2West Prong Little Pigeon River watershed. Additionally, both gauge and radar data were used for rainfall-runoff-infiltration modeling for a 42-day period in July and August 2012. Runoff and infiltration were simulated using the conventional semi-distributed hydrological model HEC-HMS. A local bias correction of radar rainfall at the gauge location improved correlation between the radar rainfall and the gauge data. Peak daily rainfall for the August 5 storm was 93 mm (gauge) and 98 mm (radar), whereas average daily rainfall for the 42-day period was 10 mm and 7.75 mm, respectively. Over the study period, simulated daily infiltration declined from 28 mm to 0.5 mm for the gauge and from 15 mm to 0.14 mm for radar, indicating essentially saturated conditions on the day of the debris flow.

In this dissertation, we have developed computer vision methods for measurement of rail gauge, and reliable identification and localization of structural defects in railroad tracks. The rail gauge is the distance between the innermost sides of the two parallel steel rails. We have developed two methods for evaluation of rail gauge. These methods were designed for different hardware setups: the first method works with two pairs of unaligned video cameras while the second method works with depth maps generated by paired laser range scanners. We have also developed a method for detection of rail defects such as damaged or missed rail fasteners, tie clips, and bolts, based on correlation and MACH filters. Lastly, to make our algorithms perform in real-time, we have developed the GPU based library for parallel computation of the above algorithms. Rail gauge is the most important measurement for track maintenance, because deviations in gauge indicate where potential defects may exist. We have developed a vision-based method for rail gauge estimation from a pair of industrial laser range scanners. In this approach, we start with building a 3D panorama of the rail out of a stack of input scans. After the panorama is built, we apply FIR circular filtering and Gaussian smoothing to the panorama buffer to suppress the noise component. In the next step we attempt to segment the rail heads in the panorama buffer. We employ the method which detects railroad crossings or forks in the panorama buffer. If they are not present, we find the rail edge using robust line fit. If they are present we use an alternative way: we predict the rail edge positions using Kalman filter. In the next step, common to both fork/crossings conditions, we find the adjusted positions of rail edges using additional clustering in the vicinity of the edge. We approximate rail head surface by the third degree polynomial and then fit two plane surfaces to find the exact position of the rail edge. Lastly, using rail edge information, we calculate the rail gauge and smooth it with 1D Gaussian filter. We have also developed a vision-based method to estimate the rail gauge from a pair of unaligned high shutter speed calibrated cameras. In this approach, the first step is to accurately detect the rail in each of the two non-overlapping synchronous images from the two cameras installed on the data collection cart by building an edge map, and fitting lines into the edge map using the Hough transform, and detecting persistent edge lines using a history buffer. After railroad track parts are detected, we segment rails out to find rail edges and calculate the rail gauge. We have demonstrated how to apply Computer Vision methods (the correlation filters and MACH filters in particular) to find different types of railroad elements with fixed or similar appearance, like railroad clips, bolts, and rail plates, in real-time. Template-based approaches for object detection (correlation filters) directly compare gray scale image data to a predefined model or template. The drawback of the correlation filters has always been that they are neither scale nor rotation invariant, thus many different filters are needed if either scale or rotation change. The application of many filters cannot be done in real-time. We have succeeded to overcome this difficulty by using the parallel computation technology which is widely available in the GPUs of most advanced graphics cards. We have developed a library, MinGPU, which facilitates the use of GPUs for Computer Vision, and have also developed a MinGPU-based library of several Computer Vision methods, which includes, among others, an implementation of correlation filters on the GPU. We have achieved a true positive rate of 0.98 for fastener detection using implementation of MACH filters on GPU. Besides correlation filters, MinGPU include implementations of Lucas-Kanade Optical Flow, image homographies, edge detectors and discrete filters, image pyramids, morphology operations, and some graphics primitives. We have shown that MinGPU implementation of homographies speeds up execution time approximately 600 times versus C implementation and 8000 times versus Matlab implementation. MinGPU is built upon a reusable core and thus is an easily expandable library. With the help of MinGPU, we have succeeded to make our algorithms work in real-time.

Tidal data forms the basis for understanding and quantifying sea-level rise and tidal statistics. While quality assurance methods based upon spectral and harmonic analysis have been applied to individual tidal records, these methods have not been used to assess global tidal datasets. In this thesis, four west coast tidal records were examined using harmonic analysis methods to investigate uncertainty on a monthly averaged basis. Uncertainty was identified using a method that quantifies time lag as a linear regression of height difference between a predicted and measured tidal height and the predicted rate of change of tidal height. Errors identified through this method were validated by visual inspection of qualitative records and digitization of daily staff/gauge comparisons. Of the 1188 total months investigated using the time-lag based estimates, 41 months of high uncertainty were identified validated through comparison with staff/gauge comparisons. Six additional months of high uncertainty were identified by the time-lag based method but were not apparent in staff-gauge comparisons. An additional 55 months of possibly inadequate data were only identified by staff/gauge comparisons. These 55 cases were shown to relate to either staff measurement error or short-term gauge issues. For problems that persisted over a month, a binning approach was used to create a statistically significant relationship between estimated time lag and the uncertainty in the water level measurement. In the future, this regression could be applied to assess uncertainty in other tidal datasets.

The intention with this thesis is to investigate a dimer in a spin chain. Inorder to do that, a model from Z2-gauge theory is taken as the theoretical motivation to construct a discrete lattice with Ising spin properties. A dimer is then allowed to exist indirectly in the empty space between sites. We choose to tackle the problem through a quantum mechanical approach in 1+1-dimensions, distancing ourselves from the original description in quantum field theory. The exposition begins by reviewing the spatial construction of the entire chain as well as its components, and ends with a discussion of time development where the main concern is dispersion in addition to reflection against a static charge.