Goal Oriented Provision of Design Principles for Additive Manufacturing to Support Conceptual Design

Additive Manufacturing (AM) offers a new degree in design freedom. However, in order to exploit AM's potentials in end-use products a methodical approach and suitable tools especially during conceptual design are needed. This paper presents a methodology for application in industrial practice, which should support the component conception for additively manufactured products. The approach focuses on a benefit-oriented preparation and provision of knowledge. In addition to general design methods for abstraction and promotion of creativity, AM-specific tools are introduced which support the provision of solution principles and process-specific restrictions. A broad applicability of the solution principles is ensured by an expansion of the solution space through abstraction. Consequently, product developers are sensitised to the new design possibilities of AM, on the one hand. On the other hand, they are supported in a holistic exploitation of design potentials in ideation in order to foster innovative solution ideas. Finally, the methodological procedure and the developed tools will be demonstrated in a workshop by using an example from industrial practice of the automotive sector

Expensive multi-objective optimization of electromagnetic mixing in a liquid metal

This paper presents a novel trust-region method for the optimization of multiple expensive functions. We apply this method to a biobjective optimization problem in fluid mechanics, the optimal mixing of particles in a flow in a closed container. The three-dimensional time-dependent flows are driven by Lorentz forces that are generated by an oscillating permanent magnet located underneath the rectangular vessel. The rectangular magnet provides a spatially non-uniform magnetic field that is known analytically. The magnet oscillation creates a steady mean flow (steady streaming) similar to those observed from oscillating rigid bodies. In the optimization problem, randomly distributed mass-less particles are advected by the flow to achieve a homogeneous distribution (objective function 1) while keeping the work done to move the permanent magnet minimal (objective function 2). A single evaluation of these two objective functions may take more than two hours. For that reason, to save computational time, the proposed method uses interpolation models on trust-regions for finding descent directions. We show that, even for our significantly simplified model problem, the mixing patterns vary significantly with the control parameters, which justifies the use of improved optimization techniques and their further development

Tuning the van der Waals Interaction of Graphene with Molecules via Doping

We use scanning tunneling microscopy to visualize and thermal desorption spectroscopy to quantitatively measure that the binding of naphthalene molecules to graphene (Gr), a case of pure van der Waals (vdW) interaction, strengthens with $n$- and weakens with $p$-doping of Gr. Density functional theory calculations that include the vdW interaction in a seamless, ab initio way accurately reproduce the observed trend in binding energies. Based on a model calculation, we propose that the vdW interaction is modified by changing the spatial extent of Gr's $\pi$ orbitals via doping

Cortisol response to traumatic stress to predict PTSD symptom development – a systematic review and meta-analysis of experimental studies

Background: Pre-and post-traumatic hypothalamic–pituitary–adrenal (HPA) axis markers have been studied to predict posttraumatic stress disorder (PTSD) risk, but its acute reactivity cannot be measured in real-life settings. Experimental paradigms can depict the cortisol response to stimuli that simulate traumatic events. Objective: To review experimental studies on the cortisol response to traumatic stimuli and the correlation between cortisol and PTSD symptoms. Method: Experimental, (un-)published studies in German or English from any year were eligible if they confronted non-traumatized humans with traumatic stimuli, assessed cortisol before, during or after stimulus presentation and subsequent PTSD symptoms. The literature was searched via PubMed, PubPsych, PsychINFO, PsycArticle, Web of Science, EMBASE, ProQuest and ClinicalTrials.gov up to 16th February 2021. Risk of bias was assessed with the Cortisol Assessment List. Multilevel-meta-analyses were conducted under the random effects model. The standardized mean change (dSMC) indicated the cortisol response. Coefficient r indicated the correlations between cortisol and PTSD symptoms. Results: 14 studies, investigating 1004 individuals, were included. A cortisol response was successfully induced between 21 and 40 min post-presentation onset (kobservations = 25, dSMC = 0.15 [.03; .26]). Cortisol was not associated with overall or cluster-level PTSD symptoms. On a symptom-level, higher pre-presentation onset cortisol was correlated with lower state tension (k = 8, r = −.18 [−.35; −.01]), higher state happiness (k = 8, r = −.34 [−.59; −.03], variable inverted) and lower state anger (k = 9, r = −.14 [−.26; −.01]). Higher post-presentation onset cortisol was correlated with higher state happiness (k = 16, r = −.20 [−.33; −.06]) and lower state sadness (k = 17, r = −.16 [−.25; −.05]), whereas cortisol response was positively correlated with state anxiety (k = 9, r = .16 [0.04; 0.27]). Conclusions: Experimental paradigms effectively induce a cortisol response. Higher basal cortisol, higher cortisol, as measured after traumatic stimulus presentation, and a lower cortisol response were associated with more adaptive emotional reactions. These markers did not predict longer-term PTSD symptoms