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- ItemSteps towards a Dislocation Ontology for Crystalline Materials(Aachen, Germany : RWTH Aachen, 2021) Ihsan, Ahmad Zainul; Dessì, Danilo; Alam, Mehwish; Sack, Harald; Sandfeld, Stefan; García-Castro, Raúl; Davies, John; Antoniou, Grigoris; Fortuna, CarolinaThe field of Materials Science is concerned with, e.g., properties and performance of materials. An important class of materials are crystalline materials that usually contain “dislocations" - a line-like defect type. Dislocation decisively determine many important materials properties. Over the past decades, significant effort was put into understanding dislocation behavior across different length scales both with experimental characterization techniques as well as with simulations. However, for describing such dislocation structures there is still a lack of a common standard to represent and to connect dislocation domain knowledge across different but related communities. An ontology offers a common foundation to enable knowledge representation and data interoperability, which are important components to establish a “digital twin". This paper outlines the first steps towards the design of an ontology in the dislocation domain and shows a connection with the already existing ontologies in the materials science and engineering domain.
- ItemOrigami-Inspired Shape Memory Folding Microactuator(Basel : MDPI, 2020) Seigner, Lena; Bezsmertna, Olha; Fähler, Sebastian; Tshikwand, Georgino; Wendler, Frank; Kohl, ManfredThis paper presents the design, fabrication and performance of origami-based folding microactuators based on a cold-rolled NiTi foil of 20 µm thickness showing the one-way shape memory effect. Origami refers to a variety of techniques of transforming planar sheets into three-dimensional (3D) structures by folding, which has been introduced in science and engineering for, e.g., assembly and robotics. Here, NiTi microactuators are interconnected to rigid sections (tiles) forming an initial planar system that self-folds into a set of predetermined 3D shapes upon heating. While this concept has been demonstrated at the macro scale, we intend to transfer this concept into microtechnology by combining state-of-the art methods of micromachining. NiTi foils are micromachined by laser cutting or photolithography to achieve double-beam structures allowing for direct Joule heating with an electrical current. A thermo-mechanical treatment is used for shape setting of as-received specimens to reach a maximum folding angle of 180°. The bending moments, bending radii and load-dependent folding angles upon Joule heating are evaluated. The shape setting process is particularly effective for small bending radii, which, however generates residual plastic strain. After shape setting, unloaded beam structures show recoverable bending deflection between 0° and 140° for a maximum heating power of 900 mW. By introducing additional loads to account for the effect of the tiles, the smooth folding characteristic evolves into a sharp transition, whereby full deflection up to 180° is reached. The achieved results are an important step towards the development of cooperative multistable microactuator systems for 3D self-assembly.
- ItemThermal protection implementation of the contact overheadline based on bay controllers of electric transport traction substations in the mining industry(Sankt-Peterburg : Inst., 2021) Lantsev, Dmitry; Frolov, Vladimir; Zverev, Sergej; Uhrlandt, Dirk; Valenta, JiříThe article presents the principle of thermal protection of the contact overheadlineand substantiates the possibility of practical implementation of this principle for rail electric transport in the mining industry. The algorithm for the implementation of modern digital protection of the contact overhead line as one of the functions of the controller is described. A mathematical model of thermal protection is proposed, which follows from the solution of the heat balance equation. The model takes into account the coefficient of the electrical networktopology, as well as the coefficient of consumption of the current-carrying core of the cable, which determines the reduction in the conducting section from contact erosion and the growth of oxide films. Corrections for air flows are introduced when receiving data from an external anemometer, via telemechanics protocol. The mathematical model was tested by writing a real thermal protection program in the C programming language for the bay controller, based on the circuitry of which is the STM32F407IGT6 microcontroller for the microcontroller unit. Verification tests were carried out on a serial bay controller in 2020. The graphs for comparing the calculated and actual values of temperatures, with different flow rates of the current-carrying conductor of the DC cable, are given. To obtain data, telemechanics protocols IEC 60870-104 and Modbus TCP, PLC Segnetics SMH4 were used.
- ItemNonlinear Optical Characterization of CsPbBr3 Nanocrystals as a Novel Material for the Integration into Electro-Optic Modulators(Millersville, PA : Materials Research Forum LLC, 2020) Vitale, Francesco; De Matteis, Fabio; Casalboni, Mauro; Prosposito, Paolo; Steglich, Patrick; Ksianzou, Viachaslau; Breiler, Christian; Schrader, Sigurd; Paci, Barbara; Generosi, Amanda; Prosposito, PaoloThe present work is concerned with the investigation of the nonlinear optical response of green emissive CsPbBr3 nanocrystals, in the form of colloidal dispersions in toluene, synthesized via a room-temperature ligand-assisted supersaturation recrystallization (LASR) method. After carrying out a preliminary characterization via X-Ray Diffraction (XRD) and Absorption and Photoluminescence (PL) Spectroscopies, the optical nonlinearity of the as-obtained colloids is probed by means of a single-beam Z-scan setup. Results show that the material in question, within the sensitivity of the experimental apparatus, exhibits a nonlinear refractive index n2 that is the order of 10-15 cm2/W. Moreover, a three-photon absorption mechanism (3PA) is postulated, according to the fitting of the recorded Z-scan traces and the fundamental absorption threshold, which turns out to be off resonance with twice the energy of the laser radiation. A figure of merit is, then, calculated as an indicator of the quality of the CsPbBr3 nanocrystals as a candidate material for photonic devices, for instance, Kerr-like electro-optic modulators (EOMs).
- ItemOntology Modelling for Materials Science Experiments(Aachen, Germany : RWTH Aachen, 2021) Alam, Mehwish; Birkholz, Henk; Dessì, Danilo; Eberl, Christoph; Fliegl, Heike; Gumbsch, Peter; von Hartrott, Philipp; Mädler, Lutz; Niebel, Markus; Sack, Harald; Thomas, Akhil; Tiddi, Ilaria; Maleshkova, Maria; Pellegrini, Tassilo; de Boer, VictorMaterials are either enabler or bottleneck for the vast majority of technological innovations. The digitization of materials and processes is mandatory to create live production environments which represent physical entities and their aggregations and thus allow to represent, share, and understand materials changes. However, a common standard formalization for materials knowledge in the form of taxonomies, ontologies, or knowledge graphs has not been achieved yet. This paper sketches the e_orts in modelling an ontology prototype to describe Materials Science experiments. It describes what is expected from the ontology by introducing a use case where a process chain driven by the ontology enables the curation and understanding of experiments.
- ItemAdvancing environmental intelligence through novel approaches in soft bioinspired robotics and allied technologies: I-Seed project position paper for Environmental Intelligence in Europe(New York,NY,United States : Association for Computing Machinery, 2022) Mazzolai, Barbara; Kraus, Tobias; Pirrone, Nicola; Kooistra, Lammert; De Simone, Antonio; Cottin, Antoine; Margheri, LauraThe EU-funded FET Proactive Environmental Intelligence project "I-Seed"(Grant Agreement n. 101017940, https://www.iseedproject.eu/) targets towards the development of a radically simplified and environmentally friendly approach for environmental monitoring. Specifically, I-Seed aims at developing a new generation of self-deployable and biodegradable soft miniaturized robots, inspired by the morphology and dispersion abilities of plant seeds, able to perform low-cost, environmentally responsible, in-situ measurements. The natural functional mechanisms of seeds dispersal offer a rich source of robust, highly adaptive, mass and energy efficient mechanisms, and behavioral and morphological intelligence, which can be selected and implemented for advanced, but simple, technological inventions. I-Seed robots are conceived as unique in their movement abilities because inspired by passive mechanisms and materials of natural seeds, and unique in their environmentally friendly design because made of all biodegradable components. Sensing is based on a chemical transduction mechanism in a stimulus-responsive sensor material with fluorescence-based optical readout, which can be read via one or more drones equipped with fluorescent LiDAR technology and a software able to perform a real time georeferencing of data. The I-Seed robotic ecosystem is envisioned to be used for collecting environmental data in-situ with high spatial and temporal resolution across large remote areas where no monitoring data are available, and thus for extending current environmental sensor frameworks and data analysis systems.