Deposition and spectral performance of an inhomogeneous broadband wide-angular antireflective coating

The gradient index coatings and optical filters based on them are a challenge for fabrication. In a round-robin experiment basically the same hybrid antireflection coating for the visible spectral region has been deposited with three different techniques: electron beam evaporation, ion beam sputtering and radio frequency magnetron-sputtering. Spectral performances of such one-side and both-side coated samples have been compared with corresponding theoretical spectra of the designed profile. Also, reproducibility of each process is checked

THE du / dt FILTERS PARAMETERS AND CHARACTERISTICS DETERMINATION

Проблема обеспечения электромагнитной совместимости при использовании частотно‐регулируемого электропривода является актуальной, так как влияет на надежность и безопасность его эксплуатации. Одной из разновидностей выходных фильтров электромагнитной совместимости являются фильтры du/dt – Г‐образные фильтры нижних частот. В результате анализа параметров фильтров, выпускаемых фирмой Danfoss, получены аналитические выражения для определения их индуктивности, емкости и демпфирующего сопротивления в зависимости от мощности нагрузки преобразователя частоты. Также определены численные значения важных для синтеза фильтров характеристик.The problem of ensuring electromagnetic compatibility when using a frequency‐controlled electric drive is relevant, since it affects the reliability and safety of its operation. One of the types of output filters of electromagnetic compatibility are du/dt filters L‐shaped low‐pass filters. As a result of analyzing the parameters of the filters produced by Danfoss, analytical expressions are obtained for determining their inductance, capacitance and damping resistance depending on the load power of the frequency converter. Numerical values of the characteristics important for the synthesis of filters are also determined

Interpolation-based reduced-order modelling for steady transonic flows via manifold learning

This paper presents a parametric reduced-order model (ROM) based on manifold learning (ML) for use in steady transonic aerodynamic applications. The main objective of this work is to derive an efficient ROM that exploits the low-dimensional nonlinear solution manifold to ensure an improved treatment of the nonlinearities involved in varying the inflow conditions to obtain an accurate prediction of shocks. The reduced-order representation of the data is derived using the Isomap ML method, which is applied to a set of sampled computational fluid dynamics (CFD) data. In order to develop a ROM that has the ability to predict approximate CFD solutions at untried parameter combinations, Isomap is coupled with an interpolation method to capture the variations in parameters like the angle of attack or the Mach number. Furthermore, an approximate local inverse mapping from the reduced-order representation to the full CFD solution space is introduced. The proposed ROM, called Isomap+I, is applied to the two-dimensional NACA 64A010 airfoil and to the 3D LANN wing. The results are compared to those obtained by proper orthogonal decomposition plus interpolation (POD+I) and to the full-order CFD model

Optimized Symbol Mappings for Bit-Interleaved Coded Modulation with Iterative Decoding

We investigate bit-interleaved coded modulation with iterative decoding (BICM-ID) for bandwidth efficient transmission, where the bit error rate is reduced through iterations between a multilevel demapper and a simple channel decoder. In order to achieve a significant turbo-gain, the assignment strategy of the binary indices to signal points is crucial. We address the problem of finding the most suitable index assignments to arbitrary, high order signal constellations. A new method based on the binary switching algorithm is proposed that finds optimized mappings outperforming previously known ones

CFD-based ROMs for aeronautical applications

The advent and development of large-scale high-fidelity computational fluid dynamics (CFD) in aircraft design is requiring, more and more, procedures and techniques aimed at reducing its computational cost in order to afford accurate but fast simulations of, e.g., the aerodynamic loads. The adoption of reduced order modeling techniques in CFD represents a promising approach to achieve this goal. Several methods have been developed to obtain reduced order models (ROMs) for the prediction of steady and unsteady aerodynamic flows using low-dimensional linear subspaces as well as nonlinear manifolds, whose performances may be further improved by applying hyper-reduction procedures. In this talk, it is presented the activity done at the German Aerospace Center (DLR) in the context of model order reduction and surrogate modeling for multidisciplinary applications, design and optimization. Different examples are shown to demonstrate the use of the ROMs in aeronautical applications, as for fusing experimental and CFD data, accelerating CFD computations, obtaining a fast loads prediction across the flight envelope, or accelerating multidisciplinary optimizations. The ROMs approches are demonstrated for airfoils, wings and aircraft in subsonic and transonic flows

A context-model for supporting work-integrated learning

This contribution introduces the so-called Workplace Learning Context as essential conceptualisation supporting self-directed learning experiences directly at the workplace. The Workplace Learning Context is to be analysed and exploited for retrieving ‘learning’ material that best-possibly matches with a knowledge worker’s current learning needs. In doing so, several different ‘flavours’ of work-integrated learning can be realised including task learning, competency-gap based support and domain-related support. The Workplace Learning Context Model, which is also outlined in this contribution, forms the technical representation of the Workplace Learning Context