Development of Ferrite-coated Soft Magnetic Composites: Correlation of Microstructure to Magnetic Properties

Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and boast high melting temperatures, thus providing adequate electrical barriers between metallic particles. These insulating layers are necessary for reducing eddy current losses by increasing resistivity in order to improve the overall magnetic efficiency and subsequent frequency range. The goals of this work are to correlate ferrite-coated Fe powder composites microstructure for the coating and core powder to magnetic properties such as permeability, coercivity, and core loss. We first explore the relevant concepts of SMC materials from their composition to processing steps to pertinent properties. This thesis employs a suite of characterization techniques for powder and composite properties. We use X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to provide a complete understanding of the effect of processing conditions on ferrite-coated Fe-based SMCs. Magnetic, mechanical, and electrical properties are then analyzed to correlate microstructural features and determine their effect on such properties. In the second part of this thesis, we present a proof of concept study on Al2O3- and Al2O3- Fe3O4-coated Fe powder composites, illustrating magnetization is highly dependent on ferromagnetic volume. We then expand on previous work to compare an ideal, crystalline state using Fe3O4-Fe thin film heterostructures to a highly strained state using bulk powder studies. Fe3O4-coated Fe composites are produced via mechanical milling and analyzed for magnetic core loss dependence on particle size, cure temperature, and microstructure of both coating and core powder. We present a significant increase in core loss related to eddy current loss from coating particles sintering and Fe grain growth. Lastly, a more resistive coating material, NiZnCu-ferrite, is applied for improved resistivity, which leads to lower eddy current loss and improved magnetic performance. By highlighting the importance of microstructure and composition on magnetic properties, a closer look at interfacial features and local microstrain are necessary and accomplished in this work. Future developments of ferrite-based SMC coatings are required to transform the use of electromagnetic devices in today's society.Ph.D., Materials Science and Engineering -- Drexel University, 201

The COVID-19 Pandemic and the Future of Working Spaces

This edited volume presents a compendium of emerging and innovative studies on the proliferation of new working spaces (NeWSps), both formal and informal (such as coworking spaces, maker spaces, fab labs, public libraries, and coffee shops), and their role during and following the COVID-19 pandemic in urban and regional development and planning. This book presents an original, interdisciplinary approach to NeWSps through three features: (i) situating the debate in the context of the COVID-19 pandemic, which has transformed NeWSp business models and the everyday work life of their owners and users; (ii) repositioning and rethinking the debate on NeWSps in the context of socioeconomics and planning and comparing conditions between before and during the COVID-19 pandemic; and (iii) providing new directions for urban and regional development and resilience to the COVID-19 pandemic, considering new ways of working and living. The 17 chapters are co-authored by both leading international scholars who have studied the proliferation of NeWSps in the last decade and young, talented researchers, resulting in a total of 55 co-authors from different disciplines (48 of whom are currently involved in the COST Action CA18214 ‘The Geography of New Working Spaces and Impact on the Periphery’ 2019–2023: www.new-working-spaces.eu). Selected comparative studies among several European countries (Western and Eastern Europe) and from the US and Lebanon are presented. The book contributes to the understanding of multi-disciplinary theoretical and practical implications of NeWSps for our society, economy, and urban/regional planning in conditions following the COVID-19 pandemic

The COVID-19 Pandemic and the Future of Working Spaces

This edited volume presents a compendium of emerging and innovative studies on the proliferation of new working spaces (NeWSps), both formal and informal (such as coworking spaces, maker spaces, fab labs, public libraries, and cofee shops), and their role during and following the COVID-19 pandemic in urban and regional development and planning. This book presents an original, interdisciplinary approach to NeWSps through three features: (i) situating the debate in the context of the COVID-19 pandemic, which has transformed NeWSp business models and the everyday work life of their owners and users; (ii) repositioning and rethinking the debate on NeWSps in the context of socioeconomics and planning and comparing conditions between before and during the COVID-19 pandemic; and (iii) providing new directions for urban and regional development and resilience to the COVID-19 pandemic, considering new ways of working and living. The 17 chapters are co-authored by both leading international scholars who have studied the proliferation of NeWSps in the last decade and young, talented researchers, resulting in a total of 55 co-authors from diferent disciplines (48 of whom are currently involved in the COST Action CA18214 ‘The Geography of New Working Spaces and Impact on the Periphery’ 2019–2023: www.newworking- spaces.eu). Selected comparative studies among several European countries (Western and Eastern Europe) and from the US and Lebanon are presented. The book contributes to the understanding of multi-disciplinary theoretical and practical implications of NeWSps for our society, economy, and urban/regional planning in conditions following the COVID-19 pandemic

Engenharia de sistemas baseada em modelos: um sistema para o tráfego & ambiente

Doutoramento em Gestão IndustrialThe contemporary world is crowded of large, interdisciplinary, complex systems made of other systems, personnel, hardware, software, information, processes, and facilities. The Systems Engineering (SE) field proposes an integrated holistic approach to tackle these socio-technical systems that is crucial to take proper account of their multifaceted nature and numerous interrelationships, providing the means to enable their successful realization. Model-Based Systems Engineering (MBSE) is an emerging paradigm in the SE field and can be described as the formalized application of modelling principles, methods, languages, and tools to the entire lifecycle of those systems, enhancing communications and knowledge capture, shared understanding, improved design precision and integrity, better development traceability, and reduced development risks. This thesis is devoted to the application of the novel MBSE paradigm to the Urban Traffic & Environment domain. The proposed system, the GUILTE (Guiding Urban Intelligent Traffic & Environment), deals with a present-day real challenging problem “at the agenda” of world leaders, national governors, local authorities, research agencies, academia, and general public. The main purposes of the system are to provide an integrated development framework for the municipalities, and to support the (short-time and real-time) operations of the urban traffic through Intelligent Transportation Systems, highlighting two fundamental aspects: the evaluation of the related environmental impacts (in particular, the air pollution and the noise), and the dissemination of information to the citizens, endorsing their involvement and participation. These objectives are related with the high-level complex challenge of developing sustainable urban transportation networks. The development process of the GUILTE system is supported by a new methodology, the LITHE (Agile Systems Modelling Engineering), which aims to lightening the complexity and burdensome of the existing methodologies by emphasizing agile principles such as continuous communication, feedback, stakeholders involvement, short iterations and rapid response. These principles are accomplished through a universal and intuitive SE process, the SIMILAR process model (which was redefined at the light of the modern international standards), a lean MBSE method, and a coherent System Model developed through the benchmark graphical modeling languages SysML and OPDs/OPL. The main contributions of the work are, in their essence, models and can be settled as: a revised process model for the SE field, an agile methodology for MBSE development environments, a graphical tool to support the proposed methodology, and a System Model for the GUILTE system. The comprehensive literature reviews provided for the main scientific field of this research (SE/MBSE) and for the application domain (Traffic & Environment) can also be seen as a relevant contribution.O mundo contemporâneo é caracterizado por sistemas de grande dimensão e de natureza marcadamente complexa, sócio-técnica e interdisciplinar. A Engenharia de Sistemas (ES) propõe uma abordagem holística e integrada para desenvolver tais sistemas, tendo em consideração a sua natureza multifacetada e as numerosas inter-relações que advêm de uma quantidade significativa de diferentes pontos de vista, competências, responsabilidades e interesses. A Engenharia de Sistemas Baseada em Modelos (ESBM) é um paradigma emergente na área da ES e pode ser descrito como a aplicação formal de princípios, métodos, linguagens e ferramentas de modelação ao ciclo de vida dos sistemas descritos. Espera-se que, na próxima década, a ESBM desempenhe um papel fundamental na prática da moderna Engenharia de Sistemas. Esta tese é dedicada à aplicação da ESBM a um desafio real que constitui uma preocupação do mundo actual, estando “na agenda” dos líderes mundiais, governantes nacionais, autoridades locais, agências de investigação, universidades e público em geral. O domínio de aplicação, o Tráfego & Ambiente, caracteriza-se por uma considerável complexidade e interdisciplinaridade, sendo representativo das áreas de interesse para a ES. Propõe-se um sistema (GUILTE) que visa dotar os municípios de um quadro de desenvolvimento integrado para adopção de Sistemas de Transporte Inteligentes e apoiar as suas operações de tráfego urbano, destacando dois aspectos fundamentais: a avaliação dos impactos ambientais associados (em especial, a poluição atmosférica e o ruído) e a divulgação de informação aos cidadãos, motivando o seu envolvimento e participação. Estes objectivos relacionam-se com o desafio mais abrangente de desenvolver redes de transporte urbano sustentáveis. O processo de desenvolvimento do sistema apoia-se numa nova metodologia (LITHE), mais ágil, que enfatiza os princípios de comunicação contínua, feedback, participação e envolvimento dos stakeholders, iterações curtas e resposta rápida. Estes princípios são concretizados através de um processo de ES universal e intuitivo (redefinido à luz dos padrões internacionais), de um método simples e de linguagens gráficas de modelação de referência (SysML e OPDs/OPL). As principais contribuições deste trabalho são, na sua essência, modelos: um modelo revisto para o processo da ES, uma metodologia ágil para ambientes de desenvolvimento baseados em modelos, uma ferramenta gráfica para suportar a metodologia proposta e o modelo de um sistema para as operações de tráfego & ambiente num contexto urbano. Contribui-se ainda com uma cuidada revisão bibliográfica para a principal área de investigação (ES/ESBM) e para o domínio de aplicação (Tráfego & Ambiente)

Streets by the sea: type, limit and elements

Tese de doutoramento, Urbanismo, Universidade de Lisboa, Faculdade de Arquitetura, 2022The city is an artefact, an unfinished object in transformation in time and space. Today, the coastal urban settlement is subject to the effects of climate change, particularly the rise in average sea level, which require new and different adaptation processes: whether metamorphosis or sedimentation. In the literature review, coastal cities are usually referred to as territory in crisis due to flooding and erosion, caused by extreme events. Yet, crisis from the Latin crisis and the Greek κρίσις, means ‘to choose’. The contemporary choice to which the architect and urban planner must respond is “how” to transform the cities. However, to implement this choice critical techniques are needed that go beyond the limits of morphological knowledge, - a showcase in which elements of the city we exposed by the remotion of layers, such as dead flesh from a body - in order to re-appropriate the operating methodological process (Muratori, 1960).This research aims to discuss how to decode the public space in contact with the sea, the seashore street, through three instrumental concepts: type, limit and elements; as syntactic compositional principles that enable the design of the urban object. A process in which we re-appropriate the space and time of the project, abandoning the immobility of the diorama in which the decoding of urban form has often been confined. In this moment of transformation we are experiencing, we need to read the territory through “typological criticism” (Tafuri, 1969) to find the invariant forms on which to base our design choices. There are no territories in crisis but cities in transformation, as always.N/

International Conference of Territorial Intelligence, Alba Iulia 2006. Vol.1, Papers on region, identity and sustainable development (deliverable 12 of caENTI, project funded under FP6 research program of the European Union), Aeternitas, Alba Iulia, 2007

GIRARDOT J.-J., PASCARU M., ILEANA I., 2007A.deliverable 12 of caENTIThese acts gather the communications of the International Conference of Territorial Intelligence that took place in ALBA IULIA in Romania, from September, the 20th to September, the 22nd 2006. This conference was the fourth conference of territorial intelligence, but the conference of ALBA IULIA is the first one that took place in the CAENTI, Coordination Action of the European Network of Territorial Intelligence, framework. Consequently, it has a particular organization. A part is devoted to the presentation of the CAENTI research activities and of their prospects. The CAENTI specific communications are published in another volume

Railway Research

This book focuses on selected research problems of contemporary railways. The first chapter is devoted to the prediction of railways development in the nearest future. The second chapter discusses safety and security problems in general, precisely from the system point of view. In the third chapter, both the general approach and a particular case study of a critical incident with regard to railway safety are presented. In the fourth chapter, the question of railway infrastructure studies is presented, which is devoted to track superstructure. In the fifth chapter, the modern system for the technical condition monitoring of railway tracks is discussed. The compact on-board sensing device is presented. The last chapter focuses on modeling railway vehicle dynamics using numerical simulation, where the dynamical models are exploited

Nanomechanics of cellulose crystals and cellulose-based polymer composites

Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: Dispersion quality and macro-mechanical properties Nanomechanical properties at the surface and tensile properties CNC diameter and interphase thickness Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on their nanomechanical properties were reported. Then the effect of CNC surface modification on the mechanical properties was studied and correlated to the crystalline structure of these materials

Cultural clusters as a local economic development strategy in rural, small town areas: the Sarah Baartman District in the Eastern Cape of South Africa

It is increasingly recognized that the cultural and creative industries (CCIs) can play an important role in economic growth and development. Governments around the world, including South Africa, are implementing culture‐led economic growth and development strategies on national and regional scales. CCIs tend to cluster around large cities because of existing hard and soft infrastructure such as networking advantages and access to skilled labour, however, much less is known about the potential of the CCIs to drive rural development. This thesis thus investigates the potential of the CCIs to cluster in small towns and rural areas. Moreover, it examines the relationship between the CCIs and socio‐economic development. The CCIs have been touted as a catalyst for economic growth and development and so have often been used in urban regeneration schemes. The Sarah Baartman District (SBD) of South Africa’s Eastern Cape has identified culture as a potential new economic driver. Establishing a new development path is necessary as the former economic mainstay, agriculture, has declined in the region, creating poverty and unemployment problems. However, the SBD has only small towns which, according to the literature, are not suited to CCI clustering. Despite this, there is evidence of cultural clustering in some of the SBD’s small towns like Nieu Bethesda and Bathurst. This research therefore conducted an audit of the CCIs in the district and used geographic information systems (GIS) to map their locations by UNESCO Framework of Cultural Statistics (FCS) domains in order to determine the extent to which clustering has occurred in a small town setting. The audit identified 1 048 CCIs operating in the district and determined that clustering is possible within some small towns, depending on their demographic, economic, social, geographic and historic characteristics. For small towns where clusters exist or the potential for cluster formation is present, the domains in which the town holds a comparative advantage, based on domain proportions and location quotients, should be pursued for local economic development (LED). In this case, Visual Arts and Crafts and Cultural Heritage were prominent throughout the district while Design and Creative Services and Performance and Celebration had small regional concentrations. Theory suggests that the presence of CCIs is linked to higher levels of economic development as the creative class is more likely to be attracted to more highly developed areas, usually large cities. Furthermore, spillover effects from cultural activity promotes further development under the virtuous cycle. To investigate the relationship between CCI clusters and socio‐economic development, the locational data of municipal level CCI numbers is overlaid with a regional development indicator, a socio‐economic status index, which is based on census data and includes economic and social components. Results show that there is a general positive trend of CCIs locating in larger numbers (clustering) in areas with higher socio‐economic development performances

On-line quality control in polymer processing using hyperspectral imaging

L’industrie du plastique se tourne de plus en plus vers les matériaux composites afin d’économiser de la matière et/ou d’utiliser des matières premières à moindres coûts, tout en conservant de bonnes propriétés. L’impressionnante adaptabilité des matériaux composites provient du fait que le manufacturier peut modifier le choix des matériaux utilisés, la proportion selon laquelle ils sont mélangés, ainsi que la méthode de mise en œuvre utilisée. La principale difficulté associée au développement de ces matériaux est l’hétérogénéité de composition ou de structure, qui entraîne généralement des défaillances mécaniques. La qualité des prototypes est normalement mesurée en laboratoire, à partir de tests destructifs et de méthodes nécessitant la préparation des échantillons. La mesure en-ligne de la qualité permettrait une rétroaction quasi-immédiate sur les conditions d’opération des équipements, en plus d’être directement utilisable pour le contrôle de la qualité dans une situation de production industrielle. L’objectif de la recherche proposée consiste à développer un outil de contrôle de qualité pour la qualité des matériaux plastiques de tout genre. Quelques sondes de type proche infrarouge ou ultrasons existent présentement pour la mesure de la composition en-ligne, mais celles-ci ne fournissent qu’une valeur ponctuelle à chaque acquisition. Ce type de méthode est donc mal adapté pour identifier la distribution des caractéristiques de surface de la pièce (i.e. homogénéité, orientation, dispersion). Afin d’atteindre cet objectif, un système d’imagerie hyperspectrale est proposé. À l’aide de cet appareil, il est possible de balayer la surface de la pièce et d’obtenir une image hyperspectrale, c’est-à-dire une image formée de l’intensité lumineuse à des centaines de longueurs d’onde et ce, pour chaque pixel de l’image. L’application de méthodes chimiométriques permettent ensuite d’extraire les caractéristiques spatiales et spectrales de l’échantillon présentes dans ces images. Finalement, les méthodes de régression multivariée permettent d’établir un modèle liant les caractéristiques identifiées aux propriétés de la pièce. La construction d’un modèle mathématique forme donc l’outil d’analyse en-ligne de la qualité des pièces qui peut également prédire et optimiser les conditions de fabrication.The use of plastic composite materials has been increasing in recent years in order to reduce the amount of material used and/or use more economic materials, all of which without compromising the properties. The impressive adaptability of these composite materials comes from the fact that the manufacturer can choose the raw materials, the proportion in which they are blended as well as the processing conditions. However, these materials tend to suffer from heterogeneous compositions and structures, which lead to mechanical weaknesses. Product quality is generally measured in the laboratory, using destructive tests often requiring extensive sample preparation. On-line quality control would allow near-immediate feedback on the operating conditions and may be transferrable to an industrial production context. The proposed research consists of developing an on-line quality control tool adaptable to plastic materials of all types. A number of infrared and ultrasound probes presently exist for on-line composition estimation, but only provide single-point values at each acquisition. These methods are therefore less adapted for identifying the spatial distribution of a sample’s surface characteristics (e.g. homogeneity, orientation, dispersion). In order to achieve this objective, a hyperspectral imaging system is proposed. Using this tool, it is possible to scan the surface of a sample and obtain a hyperspectral image, that is to say an image in which each pixel captures the light intensity at hundreds of wavelengths. Chemometrics methods can then be applied to this image in order to extract the relevant spatial and spectral features. Finally, multivariate regression methods are used to build a model between these features and the properties of the sample. This mathematical model forms the backbone of an on-line quality assessment tool used to predict and optimize the operating conditions under which the samples are processed