Computational investigation of the timber response to fire

Timber could revolutionize the construction industry by allowing rapid, cost-efficient, and sustainable construction of high-rise buildings. However, insufficient knowledge of the fire performance of timber hinders its uptake. The structural performance of timber in a fire is evaluated by the char depth after standardised heating inside a furnace. This standardised heating only represents fires in small compartments (floor area500 m2). This thesis aims to understand the charring behaviour of wood under uniform and non-uniform fires. To this end, a novel charring model of timber was developed across scales. At the microscale, a novel kinetic model reproduces over 80 experiments from the literature accurately. The model was developed using novel methodologies to arrive at an appropriate reaction scheme and identify experiments free of heat and mass transfer effects. At the mesoscale, this kinetic model is coupled with a heat and mass transfer model. The combined model reproduces blindly experiments under a wide range of conditions. With this model, I unified the three existing theories on the role of chemical kinetics. Furthermore, I demonstrate that chemical kinetics is key to reproduce transient charring behaviour, but that the variability in charring rates of different softwoods stems from their difference in material properties. At the macroscale, I predict that in non-uniform fires char depths are up to 34 % smaller than in uniform fires, but the strength loss ahead of the char front can be up to 129 % larger than in uniform fires. When taking the latter into account, the strength decay under uniform and non-uniform is comparable. Overall, this thesis provides a fundamental understanding of charring and enables engineers to improve their current design tools.Open Acces

Modulatory Effect of Cattle on Risk for Lyme Disease

TOC Summary: Low-intensity cattle grazing limits Borrelia burgdorferi s.l., but not B. miyamotoi, in vector ticks

Do sojourn effects on personality trait changes last? A five-year longitudinal study

Richter J, Zimmermann J, Neyer FJ, Kandler C. Do sojourn effects on personality trait changes last? A five-year longitudinal study. European Journal of Personality. 2020;35(3):358-382.This study examined sojourners’ long-term personality trait changes over five years, extending previous research on immediate sojourn effects. A sample of German students (N = 1,095) was surveyed thrice (T1-T3) over the course of an academic year. Sojourners (n = 498) lived abroad shortly after T1 for one or two semesters, stayers (n = 597) remained in their home country. Five years after T1, we surveyed the same participants (n = 441, 40.3%) again (T4). Beyond substantial selection effects, latent neighbor-change models revealed that small differences between sojourners’ and stayers’ openness, agreeableness, and neuroticism changes occurred early after sojourn-induced contextual change. Model estimates suggested sustained sojourn effects on openness and neuroticism changes thereafter, and a reversed effect on agreeableness change after return. Due to reduced power and low accuracy at T4, these estimates were not statistically significant. Based on model comparison analyses, however, we could rule out reversed effects for openness and accentuated effects for agreeableness and neuroticism as least likely. Moreover, separating short-term and long-term sojourners revealed no substantial differences, but recurring sojourn experiences tended to play a role in sustaining differences. We discuss implications for future studies on patterns of sojourn effects on personality trait changes

Design and practical Realization of an innovative Flywheel Concept for industrial Applications

The joint industry project ‘ETA-Fabrik’ at TU Darmstadt demonstrates different approaches to improve the energy efficiency of manufacturing processes. Within this project an innovative flywheel concept was designed and realized in order to provide energy storage and load smoothing services. The flywheel design is an outerrotor setup. The rotor is a hubless hollow cylinder made of fiber reinforced plastic (FRP). All functional components are fully integrated into the rotor. For the radial suspension homopolar active magnetic bearings (AMBs) made of soft magnetic composite are used. A permanent magnetic bearing provides axial levitation. In order to increase the systems robustness a newly developed backup bearing system in a planetary arrangement with multiple independent bearing elements is integrated. The motor generator unit is a permanent magnet synchronous machine which is connected to the factory gird via a frequency inverter. The system is operated in high vacuum in order to reduce gaseous friction. Design challenges are the segmented  sensor planes for the AMBs, the diametric enlargement of the rotor due to centrifugal forces, the anisotropic  FRP as well as the thermal stability of the rotor in vacuum environment which leads to the demand of very low rotor losses. The  paper describes the system and component design process and solutions which were incorporated in order   to meet the design restrictions and challenges

Deep brain stimulation for movement disorder treatment: Exploring frequency-dependent efficacy in a computational network model

A large scale computational model of the basal ganglia (BG) network is proposed to describes movement disorder including deep brain stimulation (DBS). The model of this complex network considers four areas of the basal ganglia network: the subthalamic nucleus (STN) as target area of DBS, globus pallidus, both pars externa and pars interna (GPe-GPi), and the thalamus (THA). Parkinsonian conditions are simulated by assuming reduced dopaminergic input and corresponding pronounced inhibitory or disinhibited projections to GPe and GPi. Macroscopic quantities can be derived which correlate closely to thalamic responses and hence motor programme fidelity. It can be demonstrated that depending on different levels of striatal projections to the GPe and GPi, the dynamics of these macroscopic quantities switch from normal conditions to parkinsonian. Simulating DBS on the STN affects the dynamics of the entire network, increasing the thalamic activity to levels close to normal, while differing from both normal and parkinsonian dynamics. Using the mentioned macroscopic quantities, the model proposes optimal DBS frequency ranges above 130 Hz.Comment: 40 pages, 16 figure

Towards Addressee Recognition in Smart Robotic Environments An Evidence Based Approach

Richter V, Kummert F. Towards Addressee Recognition in Smart Robotic Environments An Evidence Based Approach. In: Proceedings of the 1st Workshop on Embodied Interaction with Smart Environments - EISE '16. New York, NY: Association for Computing Machinery (ACM); 2016: 1