We present a study of optoelectronically active Ga(As)As quantum dots (QDs) on Al-rich AlxGa1-xAs layers with Al concentrations up to x=90%. So far, however, it has not been possible to grow optoelectronically active Ga(As)As QDs epitaxially directly on and in between Al-rich barrier layers in the AlGaInAsSb material system. A QD morphology might appear on the growth front, but the QD-like entities will not luminesce. Here, we use photoluminescence (PL) measurements to show that thin Al-free capsule layers between Al-rich barrier layers and the QD layers can solve this problem; this way, the QDs become optoelectronically active; that is, the dots become QDs. We consider antimonide QDs, that is, Ga(As)Sb QDs, either on GaAs for comparison or on AlxGa1-xAs barriers (x >10%) with GaAs capsule layers in between. We also discuss the influence of QD coupling both due to stress/strain from neighboring QDs and quantum-mechanically on the wavelength of the photoluminescence peak. Due to their mere existence, the capsule layers alter the barriers by becoming part of them. Quantum dots applications such as QD semiconductor lasers for spectroscopy or QDs as binary storage cells will profit from this additional degree of design freedom.

The present work investigates the role of higher education experience in the process of students’ adult identity formation. In the broadest sense, adult identity is “seeing oneself as an adult” (Macmillan, 2007: 20), and it lays in the core of intensive processes of personal identity formation in the years following adolescence, which are for an increasing number of youth over the past decades spent in higher education. Approaches to adulthood in prior studies reveal ongoing discussions and attempts at re-conceptualisation against changing conditions and regimes of transition to adulthood. Traditionally, the so-called “objective markers” of adulthood have dominated the discourses for a long time, emphasising role transitions and demographic features as criteria for adulthood. The new research venues adding biographical approaches and subjective experiences reveal significance of inner, psychological processes of becoming an adult. However, the problem of the role of higher education in the process of students’ adult identity has not been fully illuminated thus far. The reason for this might be sought within the domain of disciplinary orientation of the field of higher education and Educational Sciences. Higher education research focuses on the overall, “grand” effects of education, while traditional Educational Sciences have not been showing much interest in higher education topics. Substantial work has been produced from developmental sciences, psychology in particular, which has revealed an intricate forest of today’s adulthood and conditions for its attainment, leaving open a whole set of educational, social, economic, cultural antecedents, correlates and experiences affecting transition to adulthood. Besides, as analyses presented in Chapter 2 show, students’ position in dominant discourses marked by political and economic imperatives is marginal. Their experiences and voices are in a sense excluded, making it almost impossible to infer on actual students’ personal benefits of the higher education process. The theoretical framework for this research consists of Erikson’s (Erikson, 1959; 1963; 1968) positions on human development in post-adolescent years, and McAdams’s model of narrative identity (1988; 2011; 2018), which also arose from Eriksonian tradition. Psychosocial theory (Erikson, 1959; 1963; 1968) assumes that social institutions provide structure and guidance to personal development, whereby they create a niche for psychosocial moratorium enabling youth a period of “identity work” before taking on long-term adult commitments. Research over recent decades reporting that higher education provides opportunities for students’ self-growth, exploration and resolving key identity questions in a variety of fields (e.g., Adams and Fitch, 1983; Arnett, 2004a; Berman, Kennerley, Kennerley, 2008; Mayhew, Rockenbach, Bowman, Seifert, Wolniak, Pascarella, Terenzin, 2016) supports such theoretical stances. The present research intends to extend existing knowledge raising the central question: What role of higher education experience students perceive in their adult identity formation? The empirical part reports on biographical research into senior year students’ lived experiences of their developmental path and their meaning to the higher education process. Students’ experiences are approached using the qualitative technique of problem-centred interviewing (PCI), which helps focus participants’ narration on the researcher’s interest and subsequent in-depth analysis of collected experiences. In total, 40 senior year students coming from diverse backgrounds were interviewed. Data were analysed in Atlas.ti software, which enabled the coding system’s better organization and browsing through transcripts. The qualitative analysis process consisted of both inductive and deductive approaches, wherein open and thematic coding techniques were performed interchangeably. Research findings indicate that in certain groups of students – but not in all – higher education experience facilitates and enriches the process of adult identity formation granting orientation and guidelines. Students identify experiences with the highest adult identity formational potential organised in the four broad categories: relationships with teachers and peers, respectively, teaching approach and study material, and extra-curricular activities. Based on the obtained findings, four patterns of thinking about the role of higher education in students’ adult identity formation have been identified: generator of adult identity formation, a safe-zone for exploration processes, interim phase leading to adulthood, and higher education suspending adult identity formation. This formed the basis for constructing the four student types; proactive, explorer, comfort-zone and atypical student. Research findings give the rationale for rethinking the educative potential of higher education in terms of its relevance for diverse students personally – for their self-growth and forming their personal identities, in addition to the professional ones.

The objective of current research on internal combustion engines is to further reduce exhaust emissions while simultaneously reducing fuel consumption. The resulting measures often mean an increase in complexity of internal combustion engines, which on one hand increases production cost and on the other hand increases the susceptibility of the overall system to defects. It is therefore necessary to develop technologies which can generate an advantage for the consumer despite increasing complexity. Within the scope of the project “High Efficiency Diesel Engine Concept” (“Hocheffizientes Diesel-Motoren-Konzept” HDMK), funded by the Federal Ministry of Economic Affairs and Energy with TÜV Rheinland as project management organization (funding code: 19U15003A), two engine concepts were investigated and combined on a John Deere four-cylinder inline engine. On the one hand, a new cylinder activation concept ("3/4- cylinder concept") was implemented with the aim of reducing fuel consumption. On the other hand, a fully variable valve train was developed for this engine, which both improves the functionality of the 3/4-cylinder concept and can have a positive influence on exhaust emissions through internal exhaust gas recirculation. A comparison of this engine concept with its series reference based on measurement data showed a fuel economy advantage of up to 5.2% in the low load field cycles of the DLG PowerMix. The maximum fuel consumption benefit in the low load engine regime exceeded 15% in some of the operating points. As a final step, the engine was modified for the integration into an existing and working tractor, maintaining the available installation space of the powertrain.

Nachhaltigkeit und Digitalisierung sind zwei der großen Themen unserer Zeit. In beiden Kontexten wird oft von Transformation gesprochen: Wirtschaft und Gesellschaft werden sich maßgeblich verändern. Deshalb sollten die beiden Trends Digitalisierung und Nachhaltigkeit zusammen betrachtet und ihre Zusammenhänge untersucht werden. Grundsätzlich wird der Digitalisierung in der wissenschaftlichen Literatur ein Einfluss auf die Erreichung einer nachhaltigen Zukunft attestiert – sowohl positiv als auch negativ. Im Rahmen der Digitalisierungsforschung ist der Aspekt der Nachhaltigkeit zumeist mehr Zusatz als Leitbild. Ob und inwiefern eine digitale Transformation auch eine Nachhaltigkeitstransformation mit sich bringt, bleibt in der Forschung also bisher weitestgehend unbeantwortet. Daher ist es unser Ziel, eine mögliche Wirkungskette aufzustellen, die sowohl nachhaltigkeitsbezogene als auch Digitalisierungsaspekte vor dem Hintergrund der Erreichung der Agenda 2030 integriert. Der Tenor unserer Recherche: Digitalisierung wird von sich aus keine der großen Nachhaltigkeitsherausforderungen lösen, sofern sie nicht in eine klare Strategie eingebettet ist.

There is little scientific evidence regarding the cumulative effect of purposeful heading. The head-neck-torso alignment is considered to be of great importance when it comes to minimizing potential risks when heading. Therefore, this study determined the relationship between head-neck-torso alignment (cervical spine, head, thoracic spine) and the acceleration of the head, the relationship between head acceleration and maximum ball speed after head impact and differences between head accelerations throughout different heading approaches (standing, jumping, running). A total of 60 male soccer players (18.9 ± 4.0 years, 177.6 ± 14.9 cm, 73.1 ± 8.6 kg) participated in the study. Head accelerations were measured by a telemetric Noraxon DTS 3D Sensor, whereas angles for the head-neck-torso alignment and ball speed were analyzed with a Qualisys Track Manager program. No relationship at all was found for the standing, jumping and running approaches. Concerning the relationship between head acceleration and maximum ball speed after head impact only for the standing header a significant result was calculated (p = 0.024, R2 = .085). A significant difference in head acceleration (p < .001) was identified between standing, jumping and running headers. To sum up, the relationship between head acceleration and head-neck-torso alignment is more complex than initially assumed and could not be proven in this study. Furthermore first data were generated to check whether the acceleration of the head is a predictor for the resulting maximum ball speed after head impact, but further investigations have to follow. Lastly, we confirmed the results that the head acceleration differs with the approach.