Geochelone carbonaria

Number of Pages: 7Integrative BiologyGeological Science

Concepts for integrating laser polishing into an additive manufacturing system

With the introduction of Additive Manufacturing, many industrial sectors benefit from the freedom of design and capabilities of this technology. Components can be individually designed and extended with different functions. However, high effort in the post-processing is necessary, since surfaces have to be processed and support structures have to be removed. This post-processing usually takes place outside the Additive Manufacturing machine. Therefore an additional effort is necessary for the machining process, but also for pre- and post-processing of the components. For example, positioning in a CNC milling machine has to be done. It is not feasible to fabricate complete systems consisting of multiple components in a single manufacturing operation. Especially optical systems require high surface qualities. The surfaces usually have to be milled or polished. In order to install the optical system afterwards, an enormous adjustment and assembly effort is needed. This can be bypassed, when both optics and mechanics are manufactured during the same process. However, integrating subtractive post-processing should be avoided as it may cause contaminants that cannot be removed from the system. Transformative processes like laser polishing do barely cause contaminants and are more suited for parallel processing. In this work the integration of a laser polishing system is evaluated, which can be used to reduce surface roughness. The requirements for the light source, manufacturing accuracy, etc. are clarified and concepts, how the integration can be implemented are developed. In addition, possibilities for processing additional materials to manufacture optical systems in one machine are discussed. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only

Das Potential der elektrostatisch unterstützten Kraftstoffzerstäubung zur Verbesserung der Einspritzung im Verbrennungsmotor

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Kinder psychisch kranker Eltern : Hilfen und Unterstützungsmöglichkeiten für belastete Kinder, die das Bedürfnis nach Informationen haben

Die vorliegende Bachelorarbeit befasst sich mit den Hilfen und Unterstützungsmöglichkeiten für Kinder psychisch kranker Eltern. Anhand von Literaturrecherchen gehe ich auf die Bedürfnisse, die Belastungen und die Risikofaktoren der Kinder, die mit ihren psychisch kranken Eltern zusammen leben, ein. Weitere Schwerpunkte sind die Bewältigungsstrategien, welche ich thematisieren werde. Abschließend betrachte ich die Ansatzpunkte und Unterstützungsmöglichkeiten für die Praxis. Ziel ist es, das Krankheitsverständnis und die familiäre Kommunikation in den betroffenen Familien zu fördern. Die soziale Arbeit soll jenen Untersuchungsgegenstand hilfreich begleiten und gestalten

Validation of the group tasks uncertainty model (MITAG) in a German sample

Task uncertainty is a key factor in teamwork research. This study analyzed the psychometric characteristics of the Spanish Model of Group Tasks Uncertainty (MITAG) in two German samples. The participants (501 team members and 104 team leaders from a German research organization) answered the MITAG together with selected items from the German Job Diagnostic Survey (JDS) and the instrument Ambiguity facets of work (Ambiguitätsfacetten der Arbeit, AfA). Confirmatory factor analysis did not reproduce the original 4-factor structure in the German sample, although the 3 newly identified factors unclarity of goals, new situations, and non-routine resemble the original factors. Results showed sound internal consistency and confirmed the convergent and discriminant validity of the new factors. The MITAG offers a concept-based short scale for researchers and practitioners

Barrier properties of GnP-PA-extruded films

It is generally known that significant improvements in the properties of nanocomposites can be achieved with graphene types currently commercially available. However, so far this is only possible on a laboratory scale. Thus, the aim of this study was to transfer results from laboratory scale experiments to industrial processes. Therefore, nanocomposites based on polyamide (PA) and graphene nanoplatelets (GnP) were prepared in order to produce membranes with improved gas barrier properties, which are characterized by reduced permeation rates of helium. First, nanocomposites were prepared with different amounts of commercial availably graphene nanoplatelets using a semi-industrial-scale compounder. Subsequently, films were produced by compression molding at different temperatures, as well as by flat film extrusion. The extruded films were annealed at different temperatures and durations. In order to investigate the effect of thermal treatment on barrier properties in correlation to thermal, structural, and morphological properties, the films were characterized by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), optical microscopy (OM), transmission electron microscopy (TEM), melt rheology measurements, and permeation measurements. In addition to structural characterization, mechanical properties were investigated. The results demonstrate that the permeation rate is strongly influenced by the processing conditions and the filler content. If the filler content is increased, the permeation rate is reduced. The annealing process can further enhance this effect

Preparation of Photoactive Transition-Metal Layered Double Hydroxides (LDH) to Replace Dye-Sensitized Materials in Solar Cells

This work highlights the use of Fe-modified MgAl-layered double hydroxides (LDHs) to replace dye and semiconductor complexes in dye-sensitized solar cells (DSSCs), forming a layered double hydroxide solar cell (LDHSC). For this purpose, a MgAl-LDH and a Fe-modified MgAl LDH were prepared. X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy were used to analyze the structural properties, morphology, and success of the Fe-modification of the synthesized LDHs. Ultraviolet-visible (UV-Vis) absorption spectroscopy was used to analyze the photoactive behavior of these LDHs and compare it to that of TiO2 and dye-sensitized TiO2. Current-voltage (I–V) solar simulation was used to determine the fill factor (FF), open circuit voltage (VOC), short circuit current (ISC), and efficiency of the LDHSCs. It was shown that the MgFeAl-LDH can act as a simultaneous photoabsorber and charge separator, effectively replacing the dye and semiconductor complex in DSSCs and yielding an efficiency of 1.56%

Validation of the German group development (GD) questionnaire

Group Development (GD) is an important variable when researching and evaluating what makes teams successful. We analyzed the psychometric properties of the originally Spanish GD questionnaire with German participants. 501 team members and 104 team leaders, 18 to 65 years old, from a German research organization answered an online survey composed of the GD questionnaire and items related to other group processes of democracy, mutual trust, team spirit, and interest in the team's tasks. Results confirmed the unidimensional factor structure of the translated Spanish version for the German GD construct. Internal consistency, convergent and discriminant validity were good. The German GD correlated as expected to other constructs, and it showed concurrent validity with respect to the team members' motivation and interest in team tasks (r = .79, p < .01). We recommend using the GD in German samples to measure team processes that are highly relevant for team effectiveness

How and When Do Leaders Influence Employees' Well-Being? Moderated Mediation Models for Job Demands and Resources

Following the call of recent reviews on leadership and well-being, the purpose of this study is to examine how and when two contrasting leadership styles, transformational leadership (TFL) and passive-avoidant leadership (PAL), are related to employees' anxiety and thereby either promote or inhibit employees' well-being. Using the prominent job demands-resources (JD-R) model as a theoretical framework, we propose that the relationship between leadership behavior and anxiety is mediated by organizational job demands, namely, role ambiguity (RA), and job resources, namely, team climate for learning (TCL), as well as moderated by autonomy as important job characteristic. A sample of 501 knowledge workers, working in teams in a German research and development (R&D) organization, answered an online survey. We tested moderated multiple mediation models using structural equation modeling (SEM). Results demonstrated that the relationships between TFL as well as PAL on the one hand and anxiety on the other hand were fully mediated by RA and TCL. Job autonomy moderated the quality of the leadership-job demand relationship for TFL and PAL. This paper contributes to understanding the complex relationship between leadership and followers' well-being taking into account a combination of mediating and moderating job demands and resources. This is the first study that examines the effects of TFL and PAL on well-being taking into account the job demand RA and team processes and autonomy as resources