Current market situation on aircraft engines and increasing requirements of EB-PVD equipment

Equipment suppliers use forecast, demands and estimates to determine capacity requirements for coated parts and also coating development. Fuel efficiencies and longer cycle times of all modern gas turbines, especially for the aviation industry, are the key drivers for the optimization of materials and coatings. In particular EB-PVD coatings designed specifically to accomplish those efficiencies. Ytrria stabilized zirconia coatings applied by EB-PVD achieved standard for the industry over the last decade. In order to produce these coatings in reliable and cost efficient methods, coating equipment design for high throughput and extended campaign times of several days is required. The challenge for an equipment supplier is to continue to provide equipment and process improvements, realizing, that some of these may require extensive requalification of equipment and process by aviation authorities (e.g. FAA). The equipment and process improvements all take in consideration the safety features for personnel and machinery protection. As an example of process improvements which also drive equipment design is the application of double layers coatings, which have become a new standard today. Double layer coatings can be applied sequentially depending on equipment configuration. Today integrated solutions that allow for switching evaporation materials during a deposition run are required. In order to accomplish this several systems are integrated in order to provide a sophisticated and safe beam deflection system with a high flexibility of beam pattern control

A MATLAB Toolbox for the Numerical Solution of Differential-Algebraic Equations

This manual describes a MATLAB toolbox for general linear and nonlinear over- and underdetermined systems of differential-algebraic equations

Evaluating differently tutored groups in problem-based learning in a German dental curriculum: a mixed methods study

Background: It is still unclear to what extent the PBL tutor affects learning in PBL-sessions. This mixed-methods study (Part 1 and 2) evaluated the effects of facilitative (f) versus non-facilitative (nf) tutoring roles on knowledge-gain and group functioning in the field of endodontics. Methods: Part 1 was a quantitative assessment of tutor effectiveness within a prospective, experimental, single-blind, stratified, randomized, two-group intervention study. Participants attended PBL in the context of a hybrid curriculum. A validated questionnaire was used and knowledge assessments were conducted before and after the intervention. External observers rated tutor performance. Part 2 was a qualitative assessment of tutor effectiveness and consisted of semi-structured expert interviews with tutors and focus group discussions with students. Results: Part 1: f tutors obtained significantly higher scores than nf tutors with respect to learning motivation and tutor effectiveness (p ≤ 0.05). nf tuition resulted in a slightly larger knowledge gain (p = 0.08). External observers documented a significantly higher activity among facilitative tutors compared to non-facilitative tutors. Part 2: Tutors found the f role easier although this led to a less autonomous working climate. The students rated f tutoring as positive in all cases. Conclusions: With respect to PBL-group performance, students felt that groups guided in a non-facilitative fashion exhibited a higher level of independence and autonomy, especially with increasing PBL experience. In addition, students reported that more preparation was necessary for sessions guided by a non-facilitative tutor. Tutors were able to modify their role and influence group processes in a controlled manner. Results are useful for future “Train-the-Teacher” sessions

Phenomenological modeling of diverse and heterogeneous synaptic dynamics at natural density

This chapter sheds light on the synaptic organization of the brain from the perspective of computational neuroscience. It provides an introductory overview on how to account for empirical data in mathematical models, implement them in software, and perform simulations reflecting experiments. This path is demonstrated with respect to four key aspects of synaptic signaling: the connectivity of brain networks, synaptic transmission, synaptic plasticity, and the heterogeneity across synapses. Each step and aspect of the modeling and simulation workflow comes with its own challenges and pitfalls, which are highlighted and addressed in detail.Comment: 35 pages, 3 figure

Channel formation and visualization of melting and crystallization behaviors in direct‐contact latent heat storage systems

Thermal storage systems are an essential component for increasing the share of renewable energies in residential heating and for the valorization of waste heat. A key challenge for the widespread application of thermal storage systems is their limited power‐to‐capacity ratio. One potential solution for this challenge is represented by direct‐contact latent heat storage systems, in which a phase change material (PCM) is in direct contact with an immiscible heat transfer fluid (HTF). To demonstrate the applicability of the direct‐contact concept for domestic hot water production, a PCM with a phase change temperature of 59°C is chosen. To enable cost‐efficient implementation of the storage system, a eutectic mixture of two salt hydrates, magnesium chloride hexahydrate and magnesium nitrate hexahydrate, is chosen as the PCM. One key aspect for the direct‐contact concept is that, during discharge, the HTF channels in the PCM do not become clogged during the solidification of the PCM. In this study, the formation and topology of the channels in direct‐contact systems under an optimized flow condition are investigated via visual observation and X‐ray computed tomography. The elucidation of the channel structure provides information on the melting and crystallization behaviors of the PCM, which are shown schematically

Tracheoesophageal Fistula Closure in a Pediatric Patient Using a Supraclavicular Artery Island Flap

Acquired tracheoesophageal fistulas can lead to large defects with fatal complications. Surgical management is challenging but necessary to prevent respiratory infections and poor weight gain. Therefore, a reliable and pliable flap like the pedicled supraclavicular artery island flap with its wide arc of rotation and robust vascularization is needed for reconstruction. We highlight the surgical technique and postoperative measures in managing a tracheoesophageal fistula due to button battery ingestion in a 9-month-old boy with the supraclavicular artery island flap. In summary, the supraclavicular artery island flap is a safe and successful tool for closure of large acquired tracheoesophageal fistulas in pediatric patients