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991.
Pablo Ares Tommaso Cea Matthew Holwill Yi Bo Wang Rafael Roldán Francisco Guinea Daria V. Andreeva Laura Fumagalli Konstantin S. Novoselov Colin R. Woods 《Advanced materials (Deerfield Beach, Fla.)》2020,32(1):1905504
2D hexagonal boron nitride (hBN) is a wide-bandgap van der Waals crystal with a unique combination of properties, including exceptional strength, large oxidation resistance at high temperatures, and optical functionalities. Furthermore, in recent years hBN crystals have become the material of choice for encapsulating other 2D crystals in a variety of technological applications, from optoelectronic and tunneling devices to composites. Monolayer hBN, which has no center of symmetry, is predicted to exhibit piezoelectric properties, yet experimental evidence is lacking. Here, by using electrostatic force microscopy, this effect is observed as a strain-induced change in the local electric field around bubbles and creases, in agreement with theoretical calculations. No piezoelectricity is found in bilayer and bulk hBN, where the center of symmetry is restored. These results add piezoelectricity to the known properties of monolayer hBN, which makes it a desirable candidate for novel electromechanical and stretchable optoelectronic devices, and pave a way to control the local electric field and carrier concentration in van der Waals heterostructures via strain. The experimental approach used here also shows a way to investigate the piezoelectric properties of other materials on the nanoscale by using electrostatic scanning probe techniques. 相似文献
992.
Danilo Tardioli Luis Riazuelo Domenico Sicignano Carlos Rizzo Francisco Lera Jos L. Villarroel Luis Montano 《野外机器人技术杂志》2019,36(6):1074-1101
The work reported in this article describes the research advances and the lessons learned by the Robotics, Perception and Real‐Time group over a decade of research in the field of ground robotics in confined environments. This study has primarily focused on localization, navigation, and communications in tunnel‐like environments. As will be discussed, this type of environment presents several special characteristics that often make well‐established techniques fail. The aim is to share, in an open way, the experience, errors, and successes of this group with the robotics community so that those that work in such environments can avoid (some of) the errors made. At the very least, these findings can be readily taken into account when designing a solution, without needing to sift through the technical details found in the papers cited within this text. 相似文献
993.
Fonseca David García-Peñalvo Francisco José 《Universal Access in the Information Society》2019,18(3):423-430
Universal Access in the Information Society - 相似文献
994.
García-Peñalvo Francisco J. Moreno Lourdes 《Universal Access in the Information Society》2019,18(1):1-2
Universal Access in the Information Society - 相似文献
995.
Pontes Eveline Kelle Ursulino Melo Hider Machado Nogueira José Walter Araújo Firmino Nairley Cardoso Sá de Carvalho Mário Geraldo Catunda Júnior Francisco Eduardo Aragão Cavalcante Theodora Thays Arruda 《Food science and biotechnology》2019,28(3):633-639
Food Science and Biotechnology - Medicinal plants with antimicrobial action have been investigated for uses against biofilms, among which, Cymbopogon nardus, citronella, stands out as a promising... 相似文献
996.
Francisco J. Tapia-Ubeda Pablo A. Miranda Irene Roda Marco Macchi Orlando Durán 《国际生产研究杂志》2020,58(17):5299-5319
Spare parts are key operational assets in order to minimise unexpected equipment downtimes that may significantly impact a company’s results. The spare parts supply chain network supports the entire spare parts operations management and it is essential to achieve the planned goals. However, most of the traditional literature on spare parts management has not focused on the underlying supply chain network. Thus, this paper studies the integration of supply chain network design and control with traditional spare parts management. In particular, a generic network optimisation modelling structure is proposed, with simultaneous optimisation of warehouse locations and inventory control decisions, allowing minimising the total costs associated with the spare parts supply chain network. The generic model is specified based on three inventory control policies widely employed in the industry, which are suitable for managing a great variety of spare parts, i.e. (s, Q), (R, s, S) and (S-1, S). Furthermore, a solution approach is proposed based on Generalised Benders Decomposition. Finally, numerical results from a real-world application case in the process industry are shown and discussed. 相似文献
997.
Gabriel Alonso Gilles Berhault Francisco ParaguayEric Rivera Sergio FuentesRussell R Chianelli 《Materials Research Bulletin》2003,38(6):1045-1055
Molybdenum disulfide with unique mesoporous structure was synthesized from tetraalkylammonium thiometallate precursors in situ decomposed in a batch reactor in the presence of dibenzothiophene (DBT). The precursors used in this study were tetraalkylammonium thiomolybdates with alkyl groups ranging from propyl to octyl. Molybdenum disulfide thus prepared presents high surface area (from 255 up to 329 m2/g), high content of carbon (C/Mo=2.7-4.0) and type IV nitrogen adsorption-desorption isotherms when decomposed from tetrahexyl-, tetraheptyl- or tetraoctylammonium thiomolybdates. The as-formed materials are poorly crystallized with a very weak intensity of the (0 0 2) peak of the 2HMoS2 structure. Such diffraction patterns are characteristic of exfoliated samples. Characterization by TEM shows a disordered layered structure with no long range order for the MoS2 catalysts. Therefore, the nature of the alkyl group in the precursor affects both the surface area and the pore size distribution of the final MoS2 catalysts with a progressive morphological modification up to a mesoporous organization. 相似文献
998.
999.
1000.
A computational fluid dynamic model of the heat and moisture transfer during beef chilling 总被引:2,自引:0,他引:2
The unsteady heat and mass transfer process during beef carcass chilling was modelled for a three-dimensional beef carcass geometry. A three-step method was used to simulate the simultaneous heat and mass transfer process in order to reduce the computational time. In the first step, a steady state simulation of the flow field was conducted. In the second step, the local heat and mass transfer coefficients were calculated. Finally, the third step consists of the simultaneous heat and mass transfer process simulation on the meat carcass only. A separate 1-D grid was used to calculate the moisture diffusion in the meat. The simulation of a 20-h chilling run takes 5 days on a 2.5 GHz Pentium 4 computer. The model allows calculating and predicting the heat load, temperatures, weight loss and water activity. Local variations in the heat and mass transfer coefficients, temperature and water activity were found around the beef carcass. The CFD model gives temperature predictions that agree with experimental data better than any previous model. The weight loss tends to be over-predicted probably due to neglecting the resistance caused by the fat cover. 相似文献