Lead halide perovskite solar cells have shown a tremendous rise in power conversion efficiency with reported record efficiencies of over 20% making this material very promising as a low cost alternative to conventional inorganic solar cells. However, due to a differently severe "hysteretic" behaviour during current density-voltage measurements, which strongly depends on scan rate, device and measurement history, preparation method, device architecture, etc., commonly used solar cell measurements do not give reliable or even reproducible results. For the aspect of commercialization and the possibility to compare results of different devices among different laboratories, it is necessary to establish a measurement protocol which gives reproducible results
Additive Manufacturing (AM) addresses various benefits as the build-up of complex shaped parts, the possibility of functional integration, reduced lead times or the use of difficult machinable materials compared to conventional manufacturing possibilities. Beside these advantages, the use of more than one material in a component would strongly increase the field of applications in typical AM branches as energy, aerospace or medical technology.By means of multi-material build-ups, cost-intensive alloys could be only used in high-loaded areas of the part, whereas the remaining part could be fabricated with cheaper compositions. The selection of combined materials strongly depends on the requested thermophysical but also mechanical properties. Within this contribution, examples (e. g. used in the turbine business) show how alloys can be arranged to fit together, e. g. in terms of a well-chosen coefficient of thermal expansion (CTE).As can be seen in nature, the multi-material usage can be characterized by sharp intersections from one material to the other (e. g. in case of a thin corrosion protection), but also by graded structures enabling a smoother material transition (e. g. in case of dissimilar materials which are joined together without defects). The latter is shown for an example from aerospace within this paper.Another possibility is the simultaneous placement of several materials, e.g. hard carbide particles placed in a more ductile matrix composition. These particles can be varied in size (e.g. TiC vs. WC). Also the ratio between carbides and matrix alloy can be adjusted depending on its application.Especially nozzle-based free form fabrication technologies, e.g. Laser Metal Deposition (LMD), enable the utilization of more than one material. Within this contribution, possibilities to feed more than one filler material are demonstrated. In addition, results of multi-material processes are shown. Finally, this work focuses on different (potential) applications, mainly in power generation but also for medical technology or wear resistant components.
We report a high-power optically pumped semiconductor vertical external cavity surface emitting laser operating at 2-mum wavelength. The gain material consisted of 15 GaInSb quantum-wells placed within a three-lambda GaSb cavity and grown on the top of an 18-pairs AlAsSb/GaSb Bragg reflector. For thermal management we have used a transparent diamond heat spreader bonded on the top of the structure. When cooled down to 5 degrees C, the laser emitted up to 1 W of optical power in a nearly diffraction-limited Gaussian beam demonstrating the high potential of antimonide material for VECSEL fabrication.
Erbe et al. Antarctic Underwater Noise score was a refinement of noise exposure criteria. Environmental evaluations are a requirement before conducting activities in the Antarctic. Because of a lack of scientific data on impacts, requirements and noise thresholds often vary between countries that conduct these evaluations, leading to different standards across countries. Addressing the identified research needs will help to implement informed and reasonable thresholds for noise production in the Antarctic and help to protect the Antarctic environment.
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