The aim of the study was to analyse where different organic molecules situated themselves in relation to the water surface of a water microdroplet and use the resulting data to compare three different forcefields in the simulation package GROMACS. The forcefields used were: General AMBER forcefield (GAFF), Optimized potentials for liquid simulations - all atoms (OPLS-AA), and CHARMM general force field (CGenFF). A library of 146 molecules were simulated using molecular dynamics. Out of the 146 molecules only 65 resulted in useful data for the comparison of the forcefields. The molecules were placed in the centre of a water microdroplet and their movements were simulated for a duration of 1 ns. The trajectories and positions of the molecules were stored and from each simulation a density profile was generated, showing where the molecules situated themselves. The distance from the peak of the density profile to the water surface was calculated and compared between the different forcefields. To analyse the data further some of the molecules were divided into subsets based on their functional groups to see if any trends were visible. Although inconclusive, the data suggested that different forcefields were more or less agreeable depending on the functional group of the molecules, for example OPLS-AA differed from CGenFF and GAFF in the case of alcohols.

<p>The aim of the Master’s Thesis work is to study and develop algorithms for autonomous travel of a UGV (Unmanned Ground Vehicle). A vehicle for the mounting of sensors has been constructed in order to perform the work. Since the UGV is to be used outdoor in urban areas, GPS can be used. To improve precision and robustness, inertial navigation is used in addition to GPS, since GPS reception is likely to be diminished in such areas. The sensors used for navigation are consequently GPS, magnetometers, accelerometers, gyroscopes, tachometers and ultra sonic sensors measuring distance to be used in detection of obstacles. The system has been implemented in Matlab. Two alternative methods of navigation with sensor fusion have been developed; one is a decentralized method with Kalman filtering using an error model and the other is a centralized particle filter using an all-embracing model of the vehicle. The two methods have been evaluated and compared. Test results show that the two methods perform equivalently.</p><p>The autonomous travel is undertaken between predetermined waypoints. In order to steer the vehicle a PID-controller based on the error between heading and its reference value is used. The computation of the reference value is based on position and heading in comparison to the desired path. The system has been tested using different routes and the results show an evident improvement of the precision in navigation compared to using only GPS-data. This holds for both navigation methods. Simulation of collision avoidance using virtual force fields shows satisfying results as well as terrain navigation with coordinate map referencing.</p> / <p>Examensarbetet är en studie i utveckling av algoritmer för autonom förflyttning av en UGV (eng Unmanned Ground Vehicle). För ändamålet har en farkost konstruerats där budgetsensorer för navigering används. Farkosten är tänkt att färdas utomhus i tätbebyggt område och GPS används. För förbättring av noggrannhet och robusthet vid dålig GPS-mottagning används även sensorer för tröghetsnavigering vilket här innebär magnetometrar, accelerometrar, gyron och tachometrar. För hinderdetektering finns avståndsmätande ultraljudssonar. Systemet som tagits fram har implementerats i realtid i Matlab. Två olika navigeringsmetoder med sensorfusion har utprovats; en decentraliserad variant med kalmanfilter som är uppbyggd kring felmodeller och en centraliserad variant med ett partikelfilter som använder en helhetsmodell för farkosten. De båda navigeringsmetoderna har utvärderats och jämförts. Resultat visar att de båda metoderna presterar likvärdigt.</p><p>Den autonoma förflyttningen utförs mellan förutbestämda brytpunkter. För att styra farkosten har en PID-regulator baserad på felet mellan kurs och börvärde använts. Börvärdet på kurs baseras på nuvarande position och riktning relativt den önskade färdvägen. Olika körsituationer har testats och resultaten visar en markant förbättring av navigeringsprecisionen jämfört med endast GPS-mätningar för både kalman- och partikelfilter. Simuleringar på vektorfältsstyrning med virtuella kraftfält för att undvika hinder har utförts med goda resultat liksom simuleringar av kartreferenspositionering.</p>

The aim of the Master’s Thesis work is to study and develop algorithms for autonomous travel of a UGV (Unmanned Ground Vehicle). A vehicle for the mounting of sensors has been constructed in order to perform the work. Since the UGV is to be used outdoor in urban areas, GPS can be used. To improve precision and robustness, inertial navigation is used in addition to GPS, since GPS reception is likely to be diminished in such areas. The sensors used for navigation are consequently GPS, magnetometers, accelerometers, gyroscopes, tachometers and ultra sonic sensors measuring distance to be used in detection of obstacles. The system has been implemented in Matlab. Two alternative methods of navigation with sensor fusion have been developed; one is a decentralized method with Kalman filtering using an error model and the other is a centralized particle filter using an all-embracing model of the vehicle. The two methods have been evaluated and compared. Test results show that the two methods perform equivalently. The autonomous travel is undertaken between predetermined waypoints. In order to steer the vehicle a PID-controller based on the error between heading and its reference value is used. The computation of the reference value is based on position and heading in comparison to the desired path. The system has been tested using different routes and the results show an evident improvement of the precision in navigation compared to using only GPS-data. This holds for both navigation methods. Simulation of collision avoidance using virtual force fields shows satisfying results as well as terrain navigation with coordinate map referencing. / Examensarbetet är en studie i utveckling av algoritmer för autonom förflyttning av en UGV (eng Unmanned Ground Vehicle). För ändamålet har en farkost konstruerats där budgetsensorer för navigering används. Farkosten är tänkt att färdas utomhus i tätbebyggt område och GPS används. För förbättring av noggrannhet och robusthet vid dålig GPS-mottagning används även sensorer för tröghetsnavigering vilket här innebär magnetometrar, accelerometrar, gyron och tachometrar. För hinderdetektering finns avståndsmätande ultraljudssonar. Systemet som tagits fram har implementerats i realtid i Matlab. Två olika navigeringsmetoder med sensorfusion har utprovats; en decentraliserad variant med kalmanfilter som är uppbyggd kring felmodeller och en centraliserad variant med ett partikelfilter som använder en helhetsmodell för farkosten. De båda navigeringsmetoderna har utvärderats och jämförts. Resultat visar att de båda metoderna presterar likvärdigt. Den autonoma förflyttningen utförs mellan förutbestämda brytpunkter. För att styra farkosten har en PID-regulator baserad på felet mellan kurs och börvärde använts. Börvärdet på kurs baseras på nuvarande position och riktning relativt den önskade färdvägen. Olika körsituationer har testats och resultaten visar en markant förbättring av navigeringsprecisionen jämfört med endast GPS-mätningar för både kalman- och partikelfilter. Simuleringar på vektorfältsstyrning med virtuella kraftfält för att undvika hinder har utförts med goda resultat liksom simuleringar av kartreferenspositionering.

A great interest has been shown for self-assembled organic nano-structures that can be used in a variety of optoelectronic applications, from element detection to home electronics. It is known from experimental research that sexiphenyl (6P) grown on muscovite mica substrate form uniaxially self-assembled nanofibers which together with sexithiophene (6T) deposited on top gives the possibility to tune their polarized emission. A key to continue develop and explore the full potential of this technique is to understand the mechanisms behind the growth. This thesis investigate the initial growth of 6P and 6T on a 6Pˆ<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cleft(11%20%5Cbar%7B1%7D%20%5Cright)%20%20%20" /> nanofiber substrate through Molecular Dynamics (MD) simulations. The adsorption of the molecules has been simulated with Simulated Annealing (SA) where 6P align perfectly with the substrate for all coverage while 6T starts to align after a certain amount of coverage. Both molecules show a monotonic increase in the adsorption energy per molecule with an increasing coverage. The surface diffusion of the molecules has been studied and shows a higher movement for both in the direction of the longmolecular axis. / Project P25154-N20 "Hetero-epitaxy of organic-organic nanofibers"