Preparation and optimisation of transparent conducting patterns using inkjet printing

Transparent conducting patterns (TCPs) are critical components that are required to be integrated into photovoltaic (PV) cells for energy harvesting. Among the manufacturing processes that are available for the deposition of TCPs onto various substrates, inkjet printing which can be categorised as an additive dispensing process has demonstrated its competitiveness by offering numerous advantages, including non-contact, high resolution, high printing speed, low cost and low material consumption. However, the present bottlenecks to be overcome for further take-up of inkjet printing technology imperatively demand the understanding of materials behaviour involved in the ink formulation and printing process. This thesis is dedicated to the elaboration of fundamental aspects of technical challenges that have been encountered in the uses of inkjet printing technology for the generation of TCPs, thereby optimisation of functional properties of the printed patterns can be achievable through the modification of inks and optimum parameters used in the printing process. [Continues.

Recent Topics in Electromagnetic Compatibility

Recent Topics in Electromagnetic Compatability discusses several topics in electromagnetic compatibility (EMC) and electromagnetic interference (EMI), including measurements, shielding, emission, interference, biomedical devices, and numerical modeling. Over five sections, chapters address the electromagnetic spectrum of corona discharge, life cycle assessment of flexible electromagnetic shields, EMC requirements for implantable medical devices, analysis and design of absorbers for EMC applications, artificial surfaces, and media for EMC and EMI shielding, and much more

Representative hydraulic conductivities in saturated groundwater flow

Heterogeneity is the single most salient feature of hydrogeology. An enormous amount of work has been devoted during the last 30 years to addressing this issue. Our objective is to synthesize and to offer a critical appraisal of results related to the problem of finding representative hydraulic conductivities. By representative hydraulic conductivity we mean a parameter controlling the average behavior of groundwater flow within an aquifer at a given scale. Three related concepts are defined: effective hydraulic conductivity, which relates the ensemble averages of flux and head gradient; equivalent conductivity, which relates the spatial averages of flux and head gradient within a given volume of an aquifer; and interpreted conductivity, which is the one derived from interpretation of field data. Most theoretical results are related to effective conductivity, and their application to real world scenarios relies on ergodic assumptions. Fortunately, a number of results are available suggesting that conventional hydraulic test interpretations yield (interpreted) hydraulic conductivity values that can be closely linked to equivalent and/or effective hydraulic conductivities. Complex spatial distributions of geologic hydrofacies and flow conditions have a strong impact upon the existence and the actual values of representative parameters. Therefore it is not surprising that a large body of literature provides particular solutions for simplified boundary conditions and geological settings, which are, nevertheless, useful for many practical applications. Still, frequent observations of scale effects imply that efforts should be directed at characterizing well‐connected stochastic random fields and at evaluating the corresponding representative hydraulic conductivitie

Design and Optimization of a 3-D Plasmonic Huygens Metasurface for Highly-Efficient Flat Optics

For miniaturization of future USAF unmanned aerial and space systems to become feasible, accompanying sensor components of these systems must also be reduced in size, weight and power (SWaP). Metasurfaces can act as planar equivalents to bulk optics, and thus possess a high potential to meet these low-SWaP requirements. However, functional efficiencies of plasmonic metasurface architectures have been too low for practical application in the infrared (IR) regime. Huygens-like forward-scattering inclusions may provide a solution to this deficiency, but there is no academic consensus on an optimal plasmonic architecture for obtaining efficient phase control at high frequencies. This dissertation asks the question: what are the ideal topologies for generating Huygens-like metasurface building blocks across a full 2π phase space? Instead of employing any a priori assumption of fundamental scattering topologies, a genetic algorithm (GA) routine was developed to optimize a “blank slate” grid of binary voxels inside a 3D cavity, evolving the voxel bits until a near-globally optimal transmittance (T) was attained at a targeted phase. All resulting designs produced a normalized T≥80 across the entire 2π range, which is the highest metasurface efficiency reported to-date for a plasmonic solution in the IR regime

Microgravity: A Teacher's Guide With Activities in Science, Mathematics, and Technology

The purpose of this curriculum supplement guide is to define and explain microgravity and show how microgravity can help us learn about the phenomena of our world. The front section of the guide is designed to provide teachers of science, mathematics, and technology at many levels with a foundation in microgravity science and applications. It begins with background information for the teacher on what microgravity is and how it is created. This is followed with information on the domains of microgravity science research; biotechnology, combustion science, fluid physics, fundamental physics, materials science, and microgravity research geared toward exploration. The background section concludes with a history of microgravity research and the expectations microgravity scientists have for research on the International Space Station. Finally, the guide concludes with a suggested reading list, NASA educational resources including electronic resources, and an evaluation questionnaire

Effet thermoélectrique dans les métaux liquides sous champ magnétique.

Lorsqu'un champ magnétique est appliqué au cours de la solidification directionnelle, une convection dans la phase liquide peut être induite par l'effet thermoélectrique. En effet la présence d'un gradient de température le long du front de solidification peut provoquer la circulation du courant thermoélectrique, qui interagit avec le champ magnétique appliqué pour créer un écoulement (convection thermo électromagnétique-TEMC). Les conditions de transport de soluté et de l'énergie sont affectées par cette convection, donc il y a influence sur l'espacement des dendrites et la macro-ségrégation des composants de l'alliage. Dans ce travail, l'influence du champ magnétique sur la solidification directionnelle d'alliages métalliques est étudiée. Des travaux expérimentaux de la solidification directionnelle de Sn-Pb et Sn-Bi alliages sont réalisés. La solidification directionnelle dans la configuration Bridgman est effectuée avec ou sans champ magnétique appliqué. L'influence, sur la solidification, du champ magnétique et d'un courant électrique (AC et DC) appliqués est étudiée. Les mouvements du liquide provoquent de fortes macro-ségrégations ainsi qu'un modification des espacements interdendritiques. Les résultats expérimentaux sont interprétés à la lumière d'une modélisation heuristique. Le cas d'un champ magnétique tournant a été aussi étudié. Ainsi, la valeur de la rotation du champ est choisie pour ralentir assez brassage électromagnétique sans pour autant supprimer les effets de TEMC. À faible vitesse de tirage et faible vitesse de rotation faible champ une macro-ségrégation en forme de spirale a pu être obtenue.If magnetic field is applied during directional solidification, liquid phase convection can be induced by means of thermoelectromagnetic effect. Temperature gradient at the solidification front can cause thermoelectric current circulation, which then interacts with field and creates convection (Thermoelectromagnetic convection-TEMC). Solute and energy transport conditions are affected by this convection, thus it influences dendrite spacing and macrosegregation of the alloys. In this work magnetic field influence on the directional solidification of metallic alloys is studied. Experimental work of directional solidification of Sn-Pb and Sn-Bi alloys is done. Alloys are directionally solidified in Bridgman setup without or with applied magnetic field. Influence on the structure by magnetic field and applied electric current (AC and DC) is studied in this work. Analytical and experimental results are compared and interpreted. Bridgman solidification under rotating transverse magnetic field is studied as well, field rotation value is chosen to be slow enough that electromagnetic stirring does not fully suppress effects of TEMC. At low pulling velocity and low field rotation velocity spiral shaped component macrosegregation can be achieved.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Applications of Crystal Plasticity in Forming Technologies

In this Special Issue, we have gathered work on simulations of polycrystalline metals and alloys at various length scales to model multiscale localization phenomena such as slip bands, cracks, and twins. The series highlights innovative techniques that combine simulation and experiments to capture material production and guide the development of forming theories. The published work helps to understand the effect of microstructure characteristics on deformation and damage behavior under multiaxial load conditions. Furthermore, these models and the studies can be used with machine learning technologies to optimize microstructure functions for materials application and process paths

Advanced Composites

Engineering practice has revealed that innovative technologies’ structural applications require new design concepts related to developing materials with mechanical properties tailored for construction purposes. This would allow the efficient use of engineering materials. The efficiency can be understood in a simplified and heuristic manner as the optimization of performance and the proper combination of structural components, leading to the consumption of the least amount of natural resources. The solution to the eco-optimization problem, based on the adequate characterization of the materials, will enable implementing environmentally friendly engineering principles when the efficient use of advanced materials guarantees the required structural safety. Identifying fundamental relationships between the structure of advanced composites and their physical properties is the focus of this book. The collected articles explore the development of sustainable composites with valorized manufacturability corresponding to Industrial Revolution 4.0 ideology. The publications, amongst others, reveal that the application of nano-particles improves the mechanical performance of composite materials; heat-resistant aluminium composites ensure the safety of overhead power transmission lines; chemical additives can detect the impact of temperature on concrete structures. This book demonstrates that construction materials’ choice has considerable room for improvement from a scientific viewpoint, following heuristic approaches