Radio frequency (rf) atmospheric pressure glow discharges (APGDs) have received growing attention for their exciting scope of new science and their immense potential for widespread applications. While geometrically similar to conventional low-pressure discharges used in the semiconductor industry for decades, rf APGDs present new physics that require investigation. This thesis presents an experimental and computational study of helium rfAPGDs aimed at making a contribution to the current understanding of these discharges and enabling their optimization for different applications. The timely interest and significance of this work is highlighted by the publication of different parts of this thesis in 10 peer-reviewed international journals. Starting with the electron trapping in rf APGDs, the thesis looks into the electron heating mechanism responsible for sustaining the discharges, the influence of the rf excitation frequency on the discharge characteristics, the role of impurities in the discharge chemistry as well as the evolution of the discharge as the size is reduced down to microplasma dimensions. The findings of this research are based on the synergistic use of electrical measurements, optical diagnostics and self-developed computational models. With the knowledge gained from this thesis, rf-APGDs can be readily used for a wide-range of applications including biological decontaminations, nanostructure fabrication and portable gas analyzers.

Hatchling disorientation after emergence is a major factor impacting sea turtle populations. This study utilized data from over 1,200 Florida Fish and Wildlife Conservation Commission (FWC) Marine Turtle Disorientation Report forms from years 2006 to 2011 to assess changes in the severity and locations of disorientation events and the impact of municipal beach lighting ordinances. While the FWC forms were completed for all sea turtle species observed, this study focused only on loggerhead sea turtles (Caretta caretta). A Disorientation Severity Index (DSI) was derived from the number of hatchlings and the direction of their tracks leaving the nests to evaluate the changes in disorientation over six years in Broward County. The FWC forms provide a much larger database for the analysis of hatchling disorientation patterns and trends than can be derived from the more precise, but labor intensive, Hatchling Orientation Index (HOI) survey method of Witherington et al. (1996). This research differs from prior work by focusing on the information provided in the FWC Marine Turtle Disorientation Report forms; using each individual disorientation to assess changes in the severity of hatchling disorientations over time. Prior work has not used the FWC forms for analysis. Significant differences were found for average DSI between years and locations. Overall, DSI decreased significantly from 2006 to 2011 in Hillsboro Beach, Pompano Beach, Lauderdale-by-the-Sea, Fort Lauderdale, and Hollywood. This might be due to increased compliance with lighting ordinances. In addition, disorientation hotspots were identified and the DSI in these hotspots decreased significantly in central and south Fort Lauderdale, Pompano Beach, and Lauderdale-by-the-Sea. Hotspots were visually identified as R-Zone ranges with higher numbers of disorientations than in other ranges (Fig. 6). Artificial beach illumination is very prevalent in Broward County. However, there was no significant relationship between the number of types of lights that were recorded on the FWC forms and DSI. Disorientations seemed to be clustered within hotspots with known lighting issues. Management strategies should use these analyses to reassess loggerhead recovery plans to reduce disorientation hotspots and increase hatchling recruitment.

Cette thèse est consacrée à l'étude du conditionnement des parois des réacteurs de fusion, en particulier ITER. Le conditionnement est nécessaire pour contrôler l'état de surface de l'enceinte à vide et donc les performances des plasmas d'ITER.Le conditionnement du tokamak JET, ayant une paroi représentative de celle d'ITER, et son impact sur l'opération est étudié de manière approfondie.Un modèle 2D des décharges luminescentes de conditionnement est validé par des données expérimentales. Il prédit des décharges raisonnablement uniformes dans ITER.Des expériences de conditionnement sur JET montrent que l'échange isotopique est un moyen efficace pour contrôler l'inventaire de tritium dans ITER, l'efficacité d'élimination étant potentiellement comparable à la rétention prédite dans un plasma nominal.Un modèle 1D de l'hydrogène échange isotopique en béryllium est élaboré et validé. Il montre que la fluence et la température de surface déterminent l'efficacité de l'échange isotopique. / Thesis is devoted to studies of performance and efficiency of wall conditioning techniques in fusion reactors, such as ITER. Conditioning is necessary to control the state of the surface of plasma facing components to ensure plasma initiation and performance. Conditioning and operation of the JET tokamak with ITER-relevant material mix is extensively studied. A 2D model of glow conditioning discharges is developed and validated; it predicts reasonably uniform discharges in ITER. In the nuclear phase of ITER operation conditioning will be needed to control tritium inventory. It is shown here that isotopic exchange is an efficient mean to eliminate tritium from the walls by replacing it with deuterium. Extrapolations for tritium removal are comparable with expected retention per a nominal plasma pulse in ITER.A 1D model of hydrogen isotopic exchange in beryllium is developed and validated. It shows that fluence and temperature of the surface influence efficiency of the isotopic exchange.

In the present work, the abnormal glow discharge at atmospheric pressure was generated in the nitrogen-methane (1 to 5 %) gaseous mixtures related to the atmosphere of Titan. The discharge itself was monitored by optical emission spectrometry that confirmed presence of active nitrogen species and various radicals formed from methane. Besides them, the CN spectral bands were observed. Intensities of all light emitting species were studied in the dependence on applied power and composition of nitrogen-methane mixture. The rotational temperature of about 2000 K was calculated from the second positive nitrogen system. The vibrational temperature also obtained from neutral nitrogen molecule increased nearly directly with methane from 3000 K (1 % CH4) to 3600 K (5 % CH4). In the contrary, vibrational temperature obtained from nitrogen molecular ion decreased with methane in the gaseous mixture and increased with applied discharge power from 3700 K to 4200 K. The same trend showed the vibrational temperature calculated from violet system of CN with value from 4600 K to 5800 K. The stable discharge products were analysed by proton transfer time of flight mass spectrometry of the exhausting gas. Presence of many aliphatic and some aromatic hydrocarbons was confirmed as well as quite a lot of amino and cyano compounds. Increasing concentrations of methane have produced more substances with higher molecular weight and less simple substances that were likely to be consumed on more complex substances. Their relative intensities were determined under the same conditions as optical emission spectra were collected.

This thesis was written up at the Department of Breeding and Propagation of Horticultural Plants under Faculty of Horticulture Mendel University in Lednice. The thesis deals with rooting of woody species of chosen kinds of Ornamental wood. The experiment was performed for Berberis thunbergii ´Rose Glow´ and for Syringa meyeri ´Palibin´ in two terms (16.6.2016 and 1.8.2016) and in four variants. The fourth variant was for control only.

Antalet hemlösa EU-migranter har på senare år ökat kraftigt i Sverige, och närmare hälften av dem saknar inkomstkälla helt medan många andra försörjer sig genom tiggeri. Numera måste individer förutom att ta ställning till huruvida de ska ge pengar till etablerade välgörenhetsorganisationer även besluta om de ska ge pengar till tiggande EU-migranter. Utifrån antagandet att det existerar asymmetrisk information, och institutionella faktorer som kan påverka individers givande till respektive typ av välgörenhet är det intressant att undersöka om det finns skillnader i benägenheten att ge till tiggande EU-migranter jämfört med etablerade välgörenhetsorganisationer.Forskningsstudiens huvudsakliga syfte är att undersöka benägenheten hos individer att ge pengar till tiggande EU-migranter jämfört med etablerade välgörenhetsorganisationer. Vidare är syftet också att identifiera och analysera olika individspecifika egenskaper som tänkbart påverkar individers givande till respektive typ av välgörenhet. För att besvara syftet samlas primärdata in i Linköpings stad genom en enkätundersökning och analyseras sedan med hjälp av ekonometriska verktyg.Forskningsstudiens resultat indikerar att individer generellt är mindre benägna att ge pengar till tiggande EU-migranter jämfört med etablerade välgörenhetsorganisationer. De egenskaper som har betydelse för att förklara individers givande till tiggande EU-migranter är kön, ålder, härkomst, kunskap om tiggande EU-migranters livssituation och inställning till lagförslag att förbjuda tiggeri. I jämförelse till detta har ålder, utbildning, härkomst, äktenskap och sociala faktorer betydelse för att förklara givandet till etablerade välgörenhetsorganisationer. / In recent years, the number of homeless EU migrants has increased substantially in Sweden, and almost half of them lack an income whereas many others live by begging. Nowadays, individuals in addition to decide whether to give money to established charities also have to decide whether to give money to begging EU migrants. Based on the assumption that asymmetric information and institutional factors exists, which can affect each type of willingness to donate to charity, it is interesting to investigate whether there are differences in propensity to give money to begging EU migrants compared to established charities.The purpose of the research study is to examine individual’s propensity to give money to begging EU migrants compared to established charities. Furthermore, the aim is also to identify and analyze various individual characteristics that conceivably affect individuals' donation to each type of charity. To answer the purpose of the research study primary data is collected in Linkoping city by a questionnaire and the material is analyzed with econometric models.The results of the study indicate that individuals generally are less likely to give money to begging EU migrants compared with established charities. Variables that affect individuals' willingness to give money to begging EU migrants are gender, age, descent, knowledge of begging EU migrants living situation and attitude towards banning begging. Compared to this, factors that affect the willingness to donate to established charities are age, education, descent, married and social factors.

Glow Discharge Optical Emission Spectrometry (GD OES) has proved to be a versatile analytical technique for the direct analysis of solid samples. The application of a pulsed power supply to the glow discharge (GD) has a number of advantages in comparison with a continuous one and thereby broadens the analytical potential of the GD. However, because the pulsed GD (PGD) is a relatively new operation mode, the pulsing and plasma parameters as well as their influence on the analytical performance of the GD are not yet comprehensively studied. The aim of this dissertation consists in the investigation of the PGD features, which are crucial for both understanding the discharge plasma processes and analytical applications. The influence of the pulsing parameters on the PGD is ascertained and compared for direct current (dc) and radio frequency (rf) discharges. In the research attention is firstly paid on the electrical parameters of PGD, then on the sputtered crater shapes, sputtering rates and finally on the light emission. It is found that the sputtered crater shape is strongly affected by the duration of the applied pulses even when the duty cycle is fixed. The pulse length influences the intensity of the light emission as well (at constant duty cycle). Moreover this influence is different for emission lines of atoms and ions in the plasma. This phenomenon can be seen at the comparison of atomic and ionic lines of different elements. The voltage–current plots of the PGD are found to indicate heating of the discharge gas when operating at high duty cycles. Using this feature a new method for the estimation of the discharge gas temperature from the voltage-current characteristics of the PGD is developed. The calculated temperature values are compared with another temperature measurement technique. Different temperature estimation procedures have shown that the discharge gas temperature can be reduced by around 100 K when PGD is applied. The temperature measurements have also confirmed that the gas heating can be adjusted by variation of the pulsing parameters. The effect of sputtering on the Cu(In,Ga)Se2 (CIGSe) layer surface of the solar cells is described for the first time. SEM investigations of the CIGSe layer of the solar cells have shown that sputter induced effects can be reduced by variation of the pulsing parameters. With regard to the question whether dc and rf pulsed discharges behave similarly: nearly all phenomena found with dc discharges also appear in the rf case. Hence it is concluded that the pulsed rf and dc discharges are very similar in terms of the electrical properties, sputtered crater formation, light emission and temperature. It is concluded that matrix specific, as well as matrix independent quantification principles and the intensity correction developed by Arne Bengtson can be applied for the pulsed mode, if special conditions are fulfilled. CIGSe solar cell samples and thin layered electrode metallizations of SAW devices are measured and quantified with application of PGD. The proposed quantification procedures are performed at commercial GD OES devices and can be used for the analysis with application of pulsed rf discharge. The studies of the PGD performed in this dissertation are relevant for the application of the GD OES analysis in materials science. During the collaborative work with Helmholtz-Zentrum Berlin für Materialien und Energie and with the research group of Dr. Thomas Gemming at IFW Dresden the optimized pulsed GD OES measurements could be successfully applied at the investigation of thin film solar cells with CIGSe light absorbing layer and electrode matallizations of SAW devices. In case of solar cell samples pulsed GD OES depth profiling along with SIMS measurements reveal the role of the Al2O3 barrier layer in high efficiency solar cells consisting of a CIGSe/Mo/Al2O3/steel substrate layer stack (the barrier layer is to prevent the Fe diffusion into the CIGSe). The features of the CIGSe films growth are studied with help of pulsed GD OES and in situ synchrotron XRD measurements. The diffusion coefficient of Zn into the CuInS2 layer is determined for the first time from the measured GD OES depth profiles of the corresponding solar cell samples. In case of SAW samples, pulsed GD OES measurements helped to evaluate the different SAW electrode preparation procedures and to select the most suitable one. In addition pulsed GD OES depth profiling along with XPS, TEM-EDX and electrode lifetime measurements indicate the possible mechanism of power durability and lifetime improvement of the SAW devices when a small amount of Al is added to the Cu-based electrodes. / Die optische Glimmentladungsspektroskopie (engl. Glow Discharge Optical Emission Spectrometry - GD OES) hat sich als eine vielfältige und schnelle Methode für die direkte Analyse von festen Materialien erwiesen. Die Anwendung von gepulsten Glimmentladungen (GD) bietet eine Reihe von Vorteilen im Vergleich zu einer kontinuierlichen Entladung und erweitert dadurch das analytische Potential der Methode. Die praktische Anwendung von gepulsten GD erfordert jedoch ein tiefes Verständnis der Prozesse, die in der Entladung und im elektrischen System ablaufen. Der Einfluss der Puls- und Plasmaparameter auf die analytische Leistung der gepulsten GD ist bislang noch nicht umfassend erforscht worden. Die Zielstellung dieser Arbeit besteht in der Untersuchung der Eigenschaften der gepulsten GD, welche von besonderer Bedeutung sowohl für das Verständnis des Entladungsprozesses als auch für analytische Anwendungen ist. Die Auswirkungen der Pulsparameter auf die gepulste GD wurde für den Gleichstrom-(DC) und Hochfrequenz- (HF) Modus untersucht und verglichen. Die Reihenfolge der Untersuchungen wurde in dieser Arbeit wie folgt gewählt: elektrische Parameter, Sputterkraterformen, Sputterraten und Lichtemission. Die Form des Sputterkraters korreliert stark mit der Pulsdauer, selbst wenn das Tastverhältnis konstant ist. Die Pulsdauer beeinflusst nicht nur die Kraterform, sondern auch die Intensität der Emissionslinien (bei konstantem Tastverhältnis). Darüber hinaus ist dieser Einfluss unterschiedlich für Atome und Ionen. Dieses Verhalten wurde an mehreren Emissionslinien (atomar bzw. ionisch) nachgewiesen. Aus der Analyse der U-I-Kennlinien der gepulsten GD ergab sich, dass es zu einer Erhitzung des Plasmas bei höherem Tastverhältnis kommt. Dieser Effekt wurde zur Bestimmung der Plasma-Gastemperatur ausgenutzt. Die ermittelten Temperaturen wurden mit einer andere Methode verglichen. Aus der Abschätzung ergab sich, dass die Plasmatemperatur bei gepulsten GD um bis zu 100 K gesenkt werden und durch die Pulsparameter genauer eingestellt werden kann. Der Einfluss des Sputterns auf Cu(In,Ga)Se2 (CIGSe) Dünnschichten von Solarzellen wurde erstmals beschrieben. REM-Untersuchungen an GD-gesputterten CIGSe Schichten haben gezeigt, dass die Sputtereffekte durch die Variation der Pulsparameter reduziert werden können. Es konnte gezeigt werden, dass HF- und DC-Entladungen dieselben Effekte aufweisen und sich nur geringfügig voneinander unterscheiden. Daraus kann geschlussfolgert werden, dass DC- und HF-Entladungen in Bezug auf elektrische Eigenschaften, Kraterformen, Lichtemission und Temperatur sehr ähnlich sind. Die Quantifizierung der mit gepulsten GD gemessenen Tiefenprofile ergab ferner, dass die Anwendung der Quantifizierungsmethoden für den kontinuierlichen Modus unter den gegebenen Bedingungen zulässig ist. Die Tiefenprofile von Solarzellen-Schichten sowie SAW-Metallisierungen wurden anhand gepulster GD gemessen und quantifiziert. Die empfohlenen Quantifizierungsmethoden können mit kommerziellen GD OES-Geräten durchgeführt werden. Die Untersuchungen an gepulsten GD sind insbesondere relevant für GD OES-Anwendungen im Bereich der Werkstoffwissenschaft. Während der Zusammenarbeit mit dem Helmholtz-Zentrum Berlin für Materialien und Energie und der Arbeitsgruppe von Dr. Thomas Gemming (IFW Dresden) konnten optimierte, gepulste GD OES Messungen erfolgreich zur Untersuchung von Dünnschicht-Solarzellen bzw. hochleistungsbeständigen SAW-Metallisierungen angewendet werden. Für die Solarzellen haben GD OES und SIMS Messungen geholfen, die Rolle der Al2O3-Barriere in CIGSe/Mo/Al2O3 Schichtstapeln auf flexiblem Stahlsubstrat besser zu verstehen (Al2O3 soll die Diffusion der Fe-Atome in CIGSe verhindern). Die gemeinsame Untersuchung getemperter CIGSe-Schichten mit gepulster GD OES und in-situ Synchrotron-XRD ergab neue Erkenntnisse zum Schichtwachstum. Der Diffusionskoeffizient von Zn in CuInS2 wurde erstmals aus GD OES-Tiefenprofilen bestimmt. Im Fall der SAW-Metallisierungen konnte die GD OES zur Bestimmung des geeignetsten Herstellungsverfahrens einen wichtigen Beitrag leisten. Die gepulste GD OES hat neben anderen Untersuchungsmethoden wie TEM-EDX, XPS und Lebensdauermessungen die Verbesserung der Leistungsbeständigkeit von Cu-Metallisierungen durch geringen Al-Zusatz aufklären können.

Glow Discharge Optical Emission Spectrometry (GD OES) has proved to be a versatile analytical technique for the direct analysis of solid samples. The application of a pulsed power supply to the glow discharge (GD) has a number of advantages in comparison with a continuous one and thereby broadens the analytical potential of the GD. However, because the pulsed GD (PGD) is a relatively new operation mode, the pulsing and plasma parameters as well as their influence on the analytical performance of the GD are not yet comprehensively studied. The aim of this dissertation consists in the investigation of the PGD features, which are crucial for both understanding the discharge plasma processes and analytical applications. The influence of the pulsing parameters on the PGD is ascertained and compared for direct current (dc) and radio frequency (rf) discharges. In the research attention is firstly paid on the electrical parameters of PGD, then on the sputtered crater shapes, sputtering rates and finally on the light emission. It is found that the sputtered crater shape is strongly affected by the duration of the applied pulses even when the duty cycle is fixed. The pulse length influences the intensity of the light emission as well (at constant duty cycle). Moreover this influence is different for emission lines of atoms and ions in the plasma. This phenomenon can be seen at the comparison of atomic and ionic lines of different elements. The voltage–current plots of the PGD are found to indicate heating of the discharge gas when operating at high duty cycles. Using this feature a new method for the estimation of the discharge gas temperature from the voltage-current characteristics of the PGD is developed. The calculated temperature values are compared with another temperature measurement technique. Different temperature estimation procedures have shown that the discharge gas temperature can be reduced by around 100 K when PGD is applied. The temperature measurements have also confirmed that the gas heating can be adjusted by variation of the pulsing parameters. The effect of sputtering on the Cu(In,Ga)Se2 (CIGSe) layer surface of the solar cells is described for the first time. SEM investigations of the CIGSe layer of the solar cells have shown that sputter induced effects can be reduced by variation of the pulsing parameters. With regard to the question whether dc and rf pulsed discharges behave similarly: nearly all phenomena found with dc discharges also appear in the rf case. Hence it is concluded that the pulsed rf and dc discharges are very similar in terms of the electrical properties, sputtered crater formation, light emission and temperature. It is concluded that matrix specific, as well as matrix independent quantification principles and the intensity correction developed by Arne Bengtson can be applied for the pulsed mode, if special conditions are fulfilled. CIGSe solar cell samples and thin layered electrode metallizations of SAW devices are measured and quantified with application of PGD. The proposed quantification procedures are performed at commercial GD OES devices and can be used for the analysis with application of pulsed rf discharge. The studies of the PGD performed in this dissertation are relevant for the application of the GD OES analysis in materials science. During the collaborative work with Helmholtz-Zentrum Berlin für Materialien und Energie and with the research group of Dr. Thomas Gemming at IFW Dresden the optimized pulsed GD OES measurements could be successfully applied at the investigation of thin film solar cells with CIGSe light absorbing layer and electrode matallizations of SAW devices. In case of solar cell samples pulsed GD OES depth profiling along with SIMS measurements reveal the role of the Al2O3 barrier layer in high efficiency solar cells consisting of a CIGSe/Mo/Al2O3/steel substrate layer stack (the barrier layer is to prevent the Fe diffusion into the CIGSe). The features of the CIGSe films growth are studied with help of pulsed GD OES and in situ synchrotron XRD measurements. The diffusion coefficient of Zn into the CuInS2 layer is determined for the first time from the measured GD OES depth profiles of the corresponding solar cell samples. In case of SAW samples, pulsed GD OES measurements helped to evaluate the different SAW electrode preparation procedures and to select the most suitable one. In addition pulsed GD OES depth profiling along with XPS, TEM-EDX and electrode lifetime measurements indicate the possible mechanism of power durability and lifetime improvement of the SAW devices when a small amount of Al is added to the Cu-based electrodes. / Die optische Glimmentladungsspektroskopie (engl. Glow Discharge Optical Emission Spectrometry - GD OES) hat sich als eine vielfältige und schnelle Methode für die direkte Analyse von festen Materialien erwiesen. Die Anwendung von gepulsten Glimmentladungen (GD) bietet eine Reihe von Vorteilen im Vergleich zu einer kontinuierlichen Entladung und erweitert dadurch das analytische Potential der Methode. Die praktische Anwendung von gepulsten GD erfordert jedoch ein tiefes Verständnis der Prozesse, die in der Entladung und im elektrischen System ablaufen. Der Einfluss der Puls- und Plasmaparameter auf die analytische Leistung der gepulsten GD ist bislang noch nicht umfassend erforscht worden. Die Zielstellung dieser Arbeit besteht in der Untersuchung der Eigenschaften der gepulsten GD, welche von besonderer Bedeutung sowohl für das Verständnis des Entladungsprozesses als auch für analytische Anwendungen ist. Die Auswirkungen der Pulsparameter auf die gepulste GD wurde für den Gleichstrom-(DC) und Hochfrequenz- (HF) Modus untersucht und verglichen. Die Reihenfolge der Untersuchungen wurde in dieser Arbeit wie folgt gewählt: elektrische Parameter, Sputterkraterformen, Sputterraten und Lichtemission. Die Form des Sputterkraters korreliert stark mit der Pulsdauer, selbst wenn das Tastverhältnis konstant ist. Die Pulsdauer beeinflusst nicht nur die Kraterform, sondern auch die Intensität der Emissionslinien (bei konstantem Tastverhältnis). Darüber hinaus ist dieser Einfluss unterschiedlich für Atome und Ionen. Dieses Verhalten wurde an mehreren Emissionslinien (atomar bzw. ionisch) nachgewiesen. Aus der Analyse der U-I-Kennlinien der gepulsten GD ergab sich, dass es zu einer Erhitzung des Plasmas bei höherem Tastverhältnis kommt. Dieser Effekt wurde zur Bestimmung der Plasma-Gastemperatur ausgenutzt. Die ermittelten Temperaturen wurden mit einer andere Methode verglichen. Aus der Abschätzung ergab sich, dass die Plasmatemperatur bei gepulsten GD um bis zu 100 K gesenkt werden und durch die Pulsparameter genauer eingestellt werden kann. Der Einfluss des Sputterns auf Cu(In,Ga)Se2 (CIGSe) Dünnschichten von Solarzellen wurde erstmals beschrieben. REM-Untersuchungen an GD-gesputterten CIGSe Schichten haben gezeigt, dass die Sputtereffekte durch die Variation der Pulsparameter reduziert werden können. Es konnte gezeigt werden, dass HF- und DC-Entladungen dieselben Effekte aufweisen und sich nur geringfügig voneinander unterscheiden. Daraus kann geschlussfolgert werden, dass DC- und HF-Entladungen in Bezug auf elektrische Eigenschaften, Kraterformen, Lichtemission und Temperatur sehr ähnlich sind. Die Quantifizierung der mit gepulsten GD gemessenen Tiefenprofile ergab ferner, dass die Anwendung der Quantifizierungsmethoden für den kontinuierlichen Modus unter den gegebenen Bedingungen zulässig ist. Die Tiefenprofile von Solarzellen-Schichten sowie SAW-Metallisierungen wurden anhand gepulster GD gemessen und quantifiziert. Die empfohlenen Quantifizierungsmethoden können mit kommerziellen GD OES-Geräten durchgeführt werden. Die Untersuchungen an gepulsten GD sind insbesondere relevant für GD OES-Anwendungen im Bereich der Werkstoffwissenschaft. Während der Zusammenarbeit mit dem Helmholtz-Zentrum Berlin für Materialien und Energie und der Arbeitsgruppe von Dr. Thomas Gemming (IFW Dresden) konnten optimierte, gepulste GD OES Messungen erfolgreich zur Untersuchung von Dünnschicht-Solarzellen bzw. hochleistungsbeständigen SAW-Metallisierungen angewendet werden. Für die Solarzellen haben GD OES und SIMS Messungen geholfen, die Rolle der Al2O3-Barriere in CIGSe/Mo/Al2O3 Schichtstapeln auf flexiblem Stahlsubstrat besser zu verstehen (Al2O3 soll die Diffusion der Fe-Atome in CIGSe verhindern). Die gemeinsame Untersuchung getemperter CIGSe-Schichten mit gepulster GD OES und in-situ Synchrotron-XRD ergab neue Erkenntnisse zum Schichtwachstum. Der Diffusionskoeffizient von Zn in CuInS2 wurde erstmals aus GD OES-Tiefenprofilen bestimmt. Im Fall der SAW-Metallisierungen konnte die GD OES zur Bestimmung des geeignetsten Herstellungsverfahrens einen wichtigen Beitrag leisten. Die gepulste GD OES hat neben anderen Untersuchungsmethoden wie TEM-EDX, XPS und Lebensdauermessungen die Verbesserung der Leistungsbeständigkeit von Cu-Metallisierungen durch geringen Al-Zusatz aufklären können.

This article investigates the decision of consumers at bottle refund machines to either reclaim their bottle deposit or to donate the refund to a non-profit organization. The study documents the unique pre-intervention data on donating behaviour and introduces a field experiment to increase donation levels. The design comprised the strategic framing of the situation by highlighting different cues about the normative, descriptive and local expectations of charitable giving as well as cues about the warm glow of donating money. The experiment took place in 20 supermarkets in Germany and lasted for 12 months. By varying the experimental design and using different modelling approaches, the study arrives at the conclusion that individuals largely act consistent with the assumption having self-regarding preferences that are stable and difficult to change. Hence, our pre-test and postintervention data stand in sharp contrast to results from lab experiments.

Normalizing flows represent a class of generative models that exhibit a number of attractive properties, but do not always achieve state-of-the-art performance when it comes to perceived naturalness of generated samples. To improve the quality of generated samples, this thesis examines methods to enhance the expressivity of discrete-time normalizing flow models and thus their ability to capture different aspects of the data. In the first part of the thesis, we propose an invertible neural network architecture as an alternative to popular architectures like Glow that require an individual neural network per flow step. Although our proposal greatly reduces the number of parameters, it has not been done before, as such architectures are believed to not be powerful enough. For this reason, we define two optional extensions that could greatly increase the expressivity of the architecture. We use augmentation to add Gaussian noise variables to the input to achieve arbitrary hidden-layer widths that are no longer dictated by the dimensionality of the data. Moreover, we implement Piecewise Affine Activation Functions that represent a generalization of Leaky ReLU activations and allow for more powerful transformations in every individual step. The resulting three models are evaluated on two simple synthetic datasets – the two moons dataset and one generated from a mixture of eight Gaussians. Our findings indicate that the proposed architectures cannot adequately model these simple datasets and thus do not represent alternatives to current stateof-the-art models. The Piecewise Affine Activation Function significantly improved the expressivity of the invertible neural network, but could not make use of its full potential due to inappropriate assumptions about the function’s input distribution. Further research is needed to ensure that the input to this function is always standard normal distributed. We conducted further experiments with augmentation using the Glow model and could show minor improvements on the synthetic datasets when only few flow steps (two, three or four) were used. However, in a more realistic scenario, the model would encompass many more flow steps. Lastly, we generalized the transformation in the coupling layers of modern flow architectures from an elementwise affine transformation to a matrixbased affine transformation and studied the effect this had on MoGlow, a flow-based model of motion. We could show that McMoGlow, our modified version of MoGlow, consistently achieved a better training likelihood than the original MoGlow on human locomotion data. However, a subjective user study found no statistically significant difference in the perceived naturalness of the samples generated. As a possible reason for this, we hypothesize that the improvements are subtle and more visible in samples that exhibit slower movements or edge cases which may have been underrepresented in the user study. / Normalizing flows representerar en klass av generativa modeller som besitter ett antal eftertraktade egenskaper, men som inte alltid uppnår toppmodern prestanda när det gäller upplevd naturlighet hos genererade data. För att förbättra kvaliteten på dessa modellers utdata, undersöker detta examensarbete metoder för att förbättra uttrycksfullheten hos Normalizing flows-modeller i diskret tid, och därmed deras förmåga att fånga olika aspekter av datamaterialet. I den första delen av uppsatsen föreslår vi en arkitektur uppbyggt av ett inverterbart neuralt nätverk. Vårt förslag är ett alternativ till populära arkitekturer som Glow, vilka kräver individuella neuronnät för varje flödessteg. Även om vårt förslag kraftigt minskar antalet parametrar har detta inte gjorts tidigare, då sådana arkitekturer inte ansetts vara tillräckligt kraftfulla. Av den anledningen definierar vi två oberoende utökningar till arkitekturen som skulle kunna öka dess uttrycksfullhet avsevärt. Vi använder så kallad augmentation, som konkatenerar Gaussiska brusvariabler till observationsvektorerna för att uppnå godtyckliga bredder i de dolda lagren, så att deras bredd inte längre begränsas av datadimensionaliteten. Dessutom implementerar vi Piecewise Affine Activation-funktioner (PAAF), vilka generaliserar Leaky ReLU-aktiveringar genom att möjliggöra mer kraftfulla transformationer i varje enskilt steg. De resulterande tre modellerna utvärderas med hjälp av två enkla syntetiska datamängder - ”the two moons dataset” och ett som genererats genom att blanda av åtta Gaussfördelningar. Våra resultat visar att de föreslagna arkitekturerna inte kan modellera de enkla datamängderna på ett tillfredsställande sätt, och därmed inte utgör kompetitiva alternativ till nuvarande moderna modeller. Den styckvisa aktiveringsfunktionen förbättrade det inverterbara neurala nätverkets uttrycksfullhet avsevärt, men kunde inte utnyttja sin fulla potential på grund av felaktiga antaganden om funktionens indatafördelning. Ytterligare forskning behövs för att hantera detta problem. Vi genomförde ytterligare experiment med augmentation av Glow-modellen och kunde påvisa vissa förbättringar på de syntetiska dataseten när endast ett fåtal flödessteg (två, tre eller fyra) användes. Däremot omfattar modeller i mer realistiska scenarion många fler flödessteg. Slutligen generaliserade vi transformationen i kopplingslagren hos moderna flödesarkitekturer från en elementvis affin transformation till en matrisbaserad affin transformation, samt studerade vilken effekt detta hade på MoGlow, en flödesbaserad modell av 3D-rörelser. Vi kunde visa att McMoGlow, vår modifierade version av MoGlow, konsekvent uppnådde bättre likelihood i träningen än den ursprungliga MoGlow gjorde på mänskliga rörelsedata. En subjektiv användarstudie på exempelrörelser genererade från MoGlow och McMoGlow visade dock ingen statistiskt signifikant skillnad i användarnas uppfattning av hur naturliga rörelserna upplevdes. Som en möjlig orsak till detta antar vi att förbättringarna är subtila och mer synliga i situationer som uppvisar långsammare rörelser eller i olika gränsfall som kan ha varit underrepresenterade i användarstudien.