Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Extrusion-based Direct Write of Functional Materials From Electronics to Magnetics

New micro- and nanoscale fabrication methods are of vital importance to drive scientific and technological advances in electronics, materials science, physics and biology areas. Direct ink writing (DW) describes a group of mask-less and contactless additive manufacturing (AM), or 3D printing, processes that involve dispensing inks, typically particle suspensions, through a deposition nozzle to create 2D or 3D material patterns with desired architecture and composition on a computer-controlled movable stage. Much of the functional material printing and electronics area remains underdeveloped for this new technology. There is a need to understand and establish the advantages and shortcomings of extrusion-based DW over other AM technologies for various applications. Further, the integration of extrusion DW with other AM technologies, such as stereolithography (SLA), remains an active area of research. In this study, we performed a comprehensive study of the relationships between ink properties/machine parameters and the printed line dimensions, including parametric studies of the machine parameters, an in-nozzle flow dynamics simulation, and a preliminary 3D comprehensive flow dynamics simulation. We explored the boundary and possibilities of extrusion-based DW. We pushed the limit of DW printing resolution, solid content of nonspherical particles, and printed polymer-bonded magnets with the highest density and magnetic performance among all 3D printing magnet techniques. We optimized the design of DW ink from rheological, mechanical, and microscopic perspectives. We are one of the first experimentalists as of author’s knowledge to perform bimodal highly concentrated suspension rheology analysis using nonspherical particles. Great improvements in solid loading were achieved by using the best large-to-small particle size ratio and large particle volume ratio found. The data and analysis could provide a new standard and solid experimental support for functional material printing

3D Printing of Functional Materials: Surface Technology and Structural Optimization

There has been a surge in interest of 3D printing technology in the recent 5 years with respect to the equipment and materials, because this technology allows one to create sophisticated and customized parts in a manner that is more efficient regarding both material and time consumption. However, 3D printing has not yet become a mainstream technology within the established manufacturing routes. One primary factor accounting for this slow progress is the lack of a broad variety of 3D printable materials, resulting in limited functions of 3D printed parts. To bridge this gap, I present an integrated strategy to fabricate a variety of functional materials/devices through the post-printing surface modification and target-motivated structural topology. A reusable 3D printed filter was first demonstrated to remove metal ions from water. This filter was functionalized with a layer of bio-adsorbent grown on its surface using post-printing modification, and the capacity was improved through structural optimization. To further improve the working efficiency, a customized 3D all-in-one printable material system was employed, which uses only one 3D printing material, but can realize various functionalities through a post-printing process. This material system is applicable for all types of photo-polymerization based 3D printing routes, including DLP, SLA, polyjet and other emerging technologies. It has significantly extended the capacity of current 3D printing technology. The 3D printed structures were converted into useful devices with new functions or new structural metamaterials with novel properties, that are attributed to both their materials composition and structural design. For example, we have showcased the magnetically manipulated robot, strength-enhanced lattice materials with high effective strength, ultralight metal materials and mechanical-metamaterials. In this thesis, a new generation of initiator-integrated material system was also developed. Beyond being able to successfully 3D print functional devices/materials with desirable properties, I also demonstrated that this initiator-laden material can be utilized to locally repair the surface damage, allowing a self-healing ability. In general, the developed 3D printing process that incorporates surface modification and structural topology enables a new class of functional devices/materials to be produced, and opens a door for further research and development of an increasing variety of 3D printing applications. Through the work presented in this dissertation, I substantially build upon and further establish the strategy and material system for 3D printing functional devices/materials, keeping in mind components, design, engineering and application

Soft pneumatic actuators: a review of design, fabrication, modeling, sensing, control and applications

Soft robotics is a rapidly evolving field where robots are fabricated using highly deformable materials and usually follow a bioinspired design. Their high dexterity and safety make them ideal for applications such as gripping, locomotion, and biomedical devices, where the environment is highly dynamic and sensitive to physical interaction. Pneumatic actuation remains the dominant technology in soft robotics due to its low cost and mass, fast response time, and easy implementation. Given the significant number of publications in soft robotics over recent years, newcomers and even established researchers may have difficulty assessing the state of the art. To address this issue, this article summarizes the development of soft pneumatic actuators and robots up until the date of publication. The scope of this article includes the design, modeling, fabrication, actuation, characterization, sensing, control, and applications of soft robotic devices. In addition to a historical overview, there is a special emphasis on recent advances such as novel designs, differential simulators, analytical and numerical modeling methods, topology optimization, data-driven modeling and control methods, hardware control boards, and nonlinear estimation and control techniques. Finally, the capabilities and limitations of soft pneumatic actuators and robots are discussed and directions for future research are identified

Knowledge-based Modelling of Additive Manufacturing for Sustainability Performance Analysis and Decision Making

Additiivista valmistusta on pidetty käyttökelpoisena monimutkaisissa geometrioissa, topologisesti optimoiduissa kappaleissa ja kappaleissa joita on muuten vaikea valmistaa perinteisillä valmistusprosesseilla. Eduista huolimatta, yksi additiivisen valmistuksen vallitsevista haasteista on ollut heikko kyky tuottaa toimivia osia kilpailukykyisillä tuotantomäärillä perinteisen valmistuksen kanssa. Mallintaminen ja simulointi ovat tehokkaita työkaluja, jotka voivat auttaa lyhentämään suunnittelun, rakentamisen ja testauksen sykliä mahdollistamalla erilaisten tuotesuunnitelmien ja prosessiskenaarioiden nopean analyysin. Perinteisten ja edistyneiden valmistusteknologioiden mahdollisuudet ja rajoitukset määrittelevät kuitenkin rajat uusille tuotekehityksille. Siksi on tärkeää, että suunnittelijoilla on käytettävissään menetelmät ja työkalut, joiden avulla he voivat mallintaa ja simuloida tuotteen suorituskykyä ja siihen liittyvän valmistusprosessin suorituskykyä, toimivien korkea arvoisten tuotteiden toteuttamiseksi. Motivaation tämän väitöstutkimuksen tekemiselle on, meneillään oleva kehitystyö uudenlaisen korkean lämpötilan suprajohtavan (high temperature superconducting (HTS)) magneettikokoonpanon kehittämisessä, joka toimii kryogeenisissä lämpötiloissa. Sen monimutkaisuus edellyttää monitieteisen asiantuntemuksen lähentymistä suunnittelun ja prototyyppien valmistuksen aikana. Tutkimus hyödyntää tietopohjaista mallinnusta valmistusprosessin analysoinnin ja päätöksenteon apuna HTS-magneettien mekaanisten komponenttien suunnittelussa. Tämän lisäksi, tutkimus etsii mahdollisuuksia additiivisen valmistuksen toteutettavuuteen HTS-magneettikokoonpanon tuotannossa. Kehitetty lähestymistapa käyttää fysikaalisiin kokeisiin perustuvaa tuote-prosessi-integroitua mallinnusta tuottamaan kvantitatiivista ja laadullista tietoa, joka määrittelee prosessi-rakenne-ominaisuus-suorituskyky-vuorovaikutuksia tietyille materiaali-prosessi-yhdistelmille. Tuloksina saadut vuorovaikutukset integroidaan kaaviopohjaiseen malliin, joka voi auttaa suunnittelutilan tutkimisessa ja täten auttaa varhaisessa suunnittelu- ja valmistuspäätöksenteossa. Tätä varten testikomponentit valmistetaan käyttämällä kahta metallin additiivista valmistus prosessia: lankakaarihitsaus additiivista valmistusta (wire arc additive manufacturing) ja selektiivistä lasersulatusta (selective laser melting). Rakenteellisissa sovelluksissa yleisesti käytetyistä metalliseoksista (ruostumaton teräs, pehmeä teräs, luja niukkaseosteinen teräs, alumiini ja kupariseokset) testataan niiden mekaaniset, lämpö- ja sähköiset ominaisuudet. Lisäksi tehdään metalliseosten mikrorakenteen karakterisointi, jotta voidaan ymmärtää paremmin valmistusprosessin parametrien vaikutusta materiaalin ominaisuuksiin. Integroitu mallinnustapa yhdistää kerätyn kokeellisen tiedon, olemassa olevat analyyttiset ja empiiriset vuorovaikutus suhteet, sekä muut tietopohjaiset mallit (esim. elementtimallit, koneoppimismallit) päätöksenteon tukijärjestelmän muodossa, joka mahdollistaa optimaalisen materiaalin, valmistustekniikan, prosessiparametrien ja muitten ohjausmuuttujien valinnan, lopullisen 3d-tulosteun komponentin halutun rakenteen, ominaisuuksien ja suorituskyvyn saavuttamiseksi. Valmistuspäätöksenteko tapahtuu todennäköisyysmallin, eli Bayesin verkkomallin toteuttamisen kautta, joka on vankka, modulaarinen ja sovellettavissa muihin valmistusjärjestelmiin ja tuotesuunnitelmiin. Väitöstyössä esitetyn mallin kyky parantaa additiivisien valmistusprosessien suorituskykyä ja laatua, täten edistää kestävän tuotannon tavoitteita.Additive manufacturing (AM) has been considered viable for complex geometries, topology optimized parts, and parts that are otherwise difficult to produce using conventional manufacturing processes. Despite the advantages, one of the prevalent challenges in AM has been the poor capability of producing functional parts at production volumes that are competitive with traditional manufacturing. Modelling and simulation are powerful tools that can help shorten the design-build-test cycle by enabling rapid analysis of various product designs and process scenarios. Nevertheless, the capabilities and limitations of traditional and advanced manufacturing technologies do define the bounds for new product development. Thus, it is important that the designers have access to methods and tools that enable them to model and simulate product performance and associated manufacturing process performance to realize functional high value products. The motivation for this dissertation research stems from ongoing development of a novel high temperature superconducting (HTS) magnet assembly, which operates in cryogenic environment. Its complexity requires the convergence of multidisciplinary expertise during design and prototyping. The research applies knowledge-based modelling to aid manufacturing process analysis and decision making in the design of mechanical components of the HTS magnet. Further, it explores the feasibility of using AM in the production of the HTS magnet assembly. The developed approach uses product-process integrated modelling based on physical experiments to generate quantitative and qualitative information that define process-structure-property-performance interactions for given material-process combinations. The resulting interactions are then integrated into a graph-based model that can aid in design space exploration to assist early design and manufacturing decision-making. To do so, test components are fabricated using two metal AM processes: wire and arc additive manufacturing and selective laser melting. Metal alloys (stainless steel, mild steel, high-strength low-alloyed steel, aluminium, and copper alloys) commonly used in structural applications are tested for their mechanical-, thermal-, and electrical properties. In addition, microstructural characterization of the alloys is performed to further understand the impact of manufacturing process parameters on material properties. The integrated modelling approach combines the collected experimental data, existing analytical and empirical relationships, and other data-driven models (e.g., finite element models, machine learning models) in the form of a decision support system that enables optimal selection of material, manufacturing technology, process parameters, and other control variables for attaining desired structure, property, and performance characteristics of the final printed component. The manufacturing decision making is performed through implementation of a probabilistic model i.e., a Bayesian network model, which is robust, modular, and can be adapted for other manufacturing systems and product designs. The ability of the model to improve throughput and quality of additive manufacturing processes will boost sustainable manufacturing goals

Challenges of continuum robots in clinical context: a review

With the maturity of surgical robotic systems based on traditional rigid-link principles, the rate of progress slowed as limits of size and controllable degrees of freedom were reached. Continuum robots came with the potential to deliver a step change in the next generation of medical devices, by providing better access, safer interactions and making new procedures possible. Over the last few years, several continuum robotic systems have been launched commercially and have been increasingly adopted in hospitals. Despite the clear progress achieved, continuum robots still suffer from design complexity hindering their dexterity and scalability. Recent advances in actuation methods have looked to address this issue, offering alternatives to commonly employed approaches. Additionally, continuum structures introduce significant complexity in modelling, sensing, control and fabrication; topics which are of particular focus in the robotics community. It is, therefore, the aim of the presented work to highlight the pertinent areas of active research and to discuss the challenges to be addressed before the potential of continuum robots as medical devices may be fully realised

Process–Structure–Properties in Polymer Additive Manufacturing

Additive manufacturing (AM) methods have grown and evolved rapidly in recent years. AM for polymers is an exciting field and has great potential in transformative and translational research in many fields, such as biomedical, aerospace, and even electronics. Current methods for polymer AM include material extrusion, material jetting, vat polymerisation, and powder bed fusion. With the promise of more applications, detailed understanding of AM—from the processability of the feedstock to the relationship between the process–structure–properties of AM parts—has become more critical. More research work is needed in material development to widen the choice of materials for polymer additive manufacturing. Modelling and simulations of the process will allow the prediction of microstructures and mechanical properties of the fabricated parts while complementing the understanding of the physical phenomena that occurs during the AM processes. In this book, state-of-the-art reviews and current research are collated, which focus on the process–structure–properties relationships in polymer additive manufacturing

IN-SITU ADDITIVE MANUFACTURING OF METALS FOR EMBEDDING PARTS COMPATIBLE WITH LIQUID METALS TO ENHANCE THERMAL PERFORMANCE OF AVIONICS FOR SPACECRAFT

With advances in micromachinery, the aggregation of sensors, and more powerful microcontroller platforms on satellites, the size of avionics for space missions are getting dramatically smaller with faster processing speeds. This has resulted in greater localized heat generation, requiring more reliable thermal management systems to enhance the thermal performance of the avionics. The emergence of advanced additive manufacturing (AM), such as selective laser melting (SLM) and engineering materials, such as low-melting eutectic liquid metal (LM) alloys and synthetics ceramics offer new opportunities for thermal cooling systems. Therefore, there has been an opportunity for adapting in-situ AM to overcome limitations of traditional manufacturing in thermal application, where improvements can be achieved through reducing thermal contract resistance of multi-layer interfaces. This dissertation investigates adapting in-situ AM technologies to embed LM compatible prefabricated components, such as ceramic tubes, inside of metals without the need for a parting surface, resulting in more intimate contact between the metal and ceramic and a reduction in the interfacial thermal resistance. A focus was placed on using more ubiquitous powder bed AM technologies, where it was determined that the morphology of the prefabricated LM compatible ceramic tubes had to be optimized to prevent collision with the apparatus of powder bed based AM. Furthermore, to enhance the wettability of the ceramic tubes during laser fusion, the surfaces were electroplated, resulting in a 1.72X improvement in heat transfer compared to cold plates packaged by conventional assembly. Additionally, multiple AM technologies synergistically complement with cross platform tools such as magnetohydrodynamic (MHD) to solve the corrosion problem in the use of low melting eutectic alloy in geometrically complex patterns as an active cooling system with no moving parts. The MHD pumping system was designed using FEA and CFD simulations to approximate Maxwell and Navier-Stokes equations, were then validated using experiments with model heat exchanger to determine the tradeoff in performance with conventional pumping systems. The MHD cooling prototype was shown to reach volumetric flow rates of up to 650 mm3/sec and generated flow pressure due to Lorentz forces of up to 230 Pa, resulting in heat transfer improvement relative to passive prototype of 1.054

Magnetic Refrigeration: Design, construction and evaluation of a valve switched rotary prototype. Numerical modeling of a solid state magnetocaloric heat elevator.

Este trabajo tiene como objetivo aportar una nueva luz a las posibilidades de que las tecnologías de refrigeración magnética se acerquen al mercado, desplazando de su trono a los sistemas de compresión de vapor.En la introducción a esta tesis, se presenta una breve descripción de los conceptos básicos de esta tecnología y sus "condiciones de frontera", y se incluyen algunas discusiones y reflexiones personales. Se ha diseñado y construido un prototipo rotatorio de refrigeración magnética para probar lo que, en ese momento y según nuestro conocimiento, constituye un nuevo diseño. La singularidad de este prototipo reside en el uso de electroválvulas en conjunto con un sistema de bombeo de fluido continuo. Otro comentario importante sobre este prototipo es que el diseño del imán se realizó mediante un proceso de optimización original. Se llevaron a cabo algunas pruebas con compuestos Gd y GdEr, y se presentan y discuten sus resultados, encontrando también las principales fuentes de pérdidas en el dispositivo. Se desarrolló un modelo de simulación por ordenador para evaluar los tiempos de relajación de temperatura de lechos porosos de esferas de un material magnetocalórico, en función de su diámetro. Esta simulación ayudó a conocer los valores límite y seleccionar el diámetro de las partículas de los materiales magnetocalóricos a utilizar. Finalmente, se realizó un estudio comparativo del uso de sistemas híbridos termoeléctricos-magnetocalóricos. Para ello, se introdujo una ecuación maestra original para el uso de esta tecnología con materiales de transición de primer orden y se programó un modelo informático para realizar simulaciones en diferentes condiciones de trabajo. Con esto, se determinó cómo debían seleccionarse los parámetros de trabajo del sistema para obtener mejoras de rendimiento con respecto a las condiciones de enfriamiento termoeléctrico puro.La tesis se estructura en una introducción general y dos partes separadas, a saber, la construcción de un prototipo rotatorio de refrigeración magnética y el estudio comparativo de sistemas híbridos termoeléctrico-magnetocalóricos. La introducción constituye un solo capítulo y las dos partes separadas comprenden ocho y dos capítulos, respectivamente.La introducción comienza con un análisis de la relevancia de las tecnologías de refrigeración y la importancia de reducir su impacto en el consumo energético mundial, así como su relación con diferentes aspectos estratégicos y ecológicos. A continuación, se aborda la necesidad de encontrar nuevas tecnologías de refrigeración que eviten o minimicen los perjuicios de los sistemas de compresión de vapor. Las tecnologías de enfriamiento magnetocalórico se introducen haciendo un breve resumen histórico y una pequeña revisión sobre los materiales magnetocalóricos relevantes, así como de la termodinámica del efecto magnetocalórico. La introducción finaliza con un análisis de la potencia de refrigeración y las condiciones de salto térmico que deben cubrir los refrigeradores magnetocalóricos, para cumplir con la regulación europea de etiquetadoenergético. Además, se presenta una discusión personal sobre cómo interpretar los gráficos de salto térmico frente a potencia de enfriamiento desde un punto de vista práctico.La Parte I presenta el diseño y construcción de un refrigerador magnético rotatorio. Una descripción completa del proceso de diseño está estructurada en diferentes secciones y subsecciones que comprenden diferentes partes del proceso de diseño. A partir de las especificaciones básicas del capítulo 2, la selección de los materiales magnetocalóricos y su forma se describe en el capítulo 3. Este capítulo incluye un modelo 1D de relajación térmica para un lecho de bolas, que se utilizó para ver las limitaciones del intercambio de calorcon diferentes diámetros de esferas y el fluido que fluye a través del lecho. El capítulo 4 explica el proceso de diseño de la carcasa del bloque de regeneradores, describiendo las principales problemáticas a resolver y las decisiones tomadas al respecto. Este capítulo incluye también una descripción del proceso de fabricación e instalación de termopares, así como una descripción de las herramientas que tuvieron que diseñarse y construirse para obtener mallas conformadas, para separar y retener las partículas esféricas en los regeneradores. En el capítulo 5, se explica detalladamente la optimización del diseño de un imán mediante un proceso original. Se incluye también una comparación del diseño optimizado con las medidas del imán fabricado. En el capítulo 6, se describe el diseño del sistema de distribución de fluidos y se presentan las consideraciones sobre la tubería, la inserción del termopar, el diseño del punto frío y la caracterización del sistema de bombeo. El capítulo 7 describe el sistema de adquisición de datos. Finalmente, el capítulo 8 presenta el proceso de prueba y los resultados obtenidos, para analizar con una discusión sobre las pérdidasy fuentes de ineficiencia observadas. Esta discusión incluye una prueba de relajación térmica realizada, que señala la ubicación de las principales áreas de pérdidas en el dispositivo.La Parte II, aunque más corta, contiene el desarrollo de importantes simulaciones que iluminan la posibilidad de que los sándwiches termoeléctrico-magnetocalórico-termoeléctrico sigan siendo considerados como ladrillos de construcción para equipos de enfriamiento magnético alternativo, aprovechando las mejores características de termoeléctricos y magnetocalóricos. El capítulo 9 es una introducción donde se explica el concepto básico y el capítulo 10 relata la simulación del sistema híbrido. En este último capítulo se describe el modelo del sándwich, incluyendo los parámetros fijos de algunas celdas Peltier comerciales que se utilizan en él, y las particularidades a tener en cuenta a la hora de trabajar con materiales de transición de fase de primer y segundo orden. De especial relevancia es la introducción de una ecuación maestra que permite modelar adecuadamente la transferencia de calor en materiales con transición de primer orden. Se comparan el enfriamiento termoeléctrico puro, el enfriamiento magnetocalórico puro con diodos térmicos pasivos y el enfriamiento magnetocalórico-termoeléctrico híbrido. Finalmente, se comparan también estos resultados con los de otros autores y se da una explicación sobre sus malos resultados.Además de esto, En el Anexo C se proporcionan un conjunto de dibujos con el diseño de diferentes partes del prototipo y utillajes adicionales, desarrollados para la construcción del prototipo.<br /

3D Printed Microfluidic Devices

3D printing has revolutionized the microfabrication prototyping workflow over the past few years. With the recent improvements in 3D printing technologies, highly complex microfluidic devices can be fabricated via single-step, rapid, and cost-effective protocols as a promising alternative to the time consuming, costly and sophisticated traditional cleanroom fabrication. Microfluidic devices have enabled a wide range of biochemical and clinical applications, such as cancer screening, micro-physiological system engineering, high-throughput drug testing, and point-of-care diagnostics. Using 3D printing fabrication technologies, alteration of the design features is significantly easier than traditional fabrication, enabling agile iterative design and facilitating rapid prototyping. This can make microfluidic technology more accessible to researchers in various fields and accelerates innovation in the field of microfluidics. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel methodological developments in 3D printing and its use for various biochemical and biomedical applications