Engineering study for a mass memory system for advanced spacecrafts Final report, 1 Dec. 1969 - 1 Jul. 1970

Mass memory system for advanced spacecraf

Laminated ferrite memory system

Feasibility study of random access laminated ferrite memory system for spacecraft us

Welding of thin sheet steels in marine applications

Many metal structures are assembled from thin plate with welded supports for stiffness to resist local loadings. However, welded joints, which require large heat input, may incur significant distortion in the finished plate. Although the causes of distortion are known, and have been the focus of number of studies, there is still a lack of fundamental understanding of process and physical parameters in causing distortion. The overall aim of this work is to identify the interaction of process and physical parameters in causing distortion of welded ferritic thin steel plates. Experimental measurements and the finite element method are used to identify the relationship between distortion and the influence of pre-existing (residual) stresses in the plates. Effect of onset of transformation temperature on distortion is examined. An improved comprehension of the mechanisms causing distortion, and a readily useable model to explore alternatives has significant potential in wide range of industries and thus is a major driving force for continued research. The ability to predict with reasonable certainty the geometry of distortion will enable users to evaluate alternative design and production parameters. The work is divided into eight chapters: The first chapter gives an introduction and lists the objectives of the research. A theoretical exploration of the problem in addition to a survey of relevant work with regard to the welding of ferritic steels, weld microstructures, residual stresses, finite element modelling (FEM) and an overview of experimental techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), neutron diffraction (ND) is given in chapter 2. In chapter 3 experimental investigation results including both post-weld and in-situ microstructure observation and residual stress distribution are presented and discussed [1, 2]. To provide a qualitative insight into fundamental understanding of development of residual stress, a finite element model that considers both the thermal and the transformation strains caused by solid-state phase transformation was developed and is presented in the chapter 4 [3]. A validated finite element model for computation of residual stresses is presented in the chapter 5 [4]. Special emphasis was placed on the effect of transformation temperature on residual stress development in both the actual weld and the model. Most of the modelling results were validated against experimental measurements. Chapter 6 presents a sensitivity study on the effect of parameter changes on distortion. An attempt was made to elucidate both the effect of transformation start temperature and the initial distortion on the final distortion [5]. Chapter 7 details application of a model for variant selection [6], which is based on work published in [7, 8] to actual welds. This work was performed to elucidate the effect of texture on residual stress. Finally the last chapter draws together the major conclusions of the thesis, and suggests future avenues of investigation to progress the research discussed here

Applications and Properties of Magnetic Nanoparticles

This Special Issue aimed to cover the new developments in the synthesis and characterization of magnetic nanoconstructs ranging from conventional metal oxide nanoparticles to novel molecule-based or hybrid multifunctional nano-objects. At the same time, the focus was on the potential of these novel magnetic nanoconstructs in several possible applications, e.g. sensing, energy storage, and nanomedicine

Functional Nanomaterials and Polymer Nanocomposites: Current Uses and Potential Applications

This book covers a broad range of subjects, from smart nanoparticles and polymer nanocomposite synthesis and the study of their fundamental properties to the fabrication and characterization of devices and emerging technologies with smart nanoparticles and polymer integration

Sustainable multifunctional materials with tailored magnetic and electrical properties for electronics applications

193 p.En el marco de la transición tecnológica impulsada por la creciente digitalización de la sociedad y la economía, existe una necesidad urgente de materiales altamente eficientes adecuados para sensores y actuadores, que también comprendan paradigmas de sostenibilidad.En este ámbito, se han desarrollado compuestos biodegradables multifuncionales avanzados basados en polímeros naturales o sintéticos. Estos materiales se procesaron en disolución con el objetivo de hacerlos aptos para tecnologías de impresión de fabricación aditiva en base solvente. Se han caracterizado las propiedades físico-químicas y mecánicas de estos materiales, así como sus propiedades funcionales en relación con su concentración. En general, los materiales que presentan funcionalidades magnéticas y eléctricas se han preparado para aplicaciones de sensores y actuadores. La actividad magnética se introdujo incorporando ferrita de cobalto (CoFe2O3) y magnetita (Fe3O4). Ambos son ferritas con magnetización de alta saturación y campos coercitivos relativamente bajos, interesantes para desarrollar sensores y actuadores magnéticos sin contacto. Respecto a los composites con propiedades eléctricas, la funcionalidad se adapta mediante cargas y aditivos de diferente naturaleza: grafito, nanocristales de celulosa (CNCs), y el líquido iónico (IL) 2-hidroxi-etil-trimetilamonio dihidrógeno fosfato [Ch][DHP]