256 research outputs found

    Automated 3D weaving continuous natural fibre and optimising harakeke fibre characterisation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University, Albany, New Zealand

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    Some possibly copyrighted Figures remain for the sake of clarity.This research investigated the design and implementation of a continuous natural fibre filament winding robot for modern artistic and structural architectural design. The idea of a new architectural construction technique based on Arduino integration was inspired by the underwater nesting structure of water spiders. It consists of the motion component, a 3-axis sliding table with limit switches, the construction of the machine, the programming and testing of the resulting microcomputer software through to a robot manufacturing process. This was based on Arduino’s new integrated development environment. In addition, the intelligent programming mode forms the preconceived pattern through winding, producing a model with unique architectural quality, and at the same time, making a structure with superior material efficiency. In terms of hardware design, the first conceptual model focused on using an open-source integrated development environment (IDE) that could be easily configured. Arduino hardware was the primary microcontroller of choice for simplicity and ease of hardware integration and software development. Stepper motor drivers are used to control the three stepper motors to accurately move the fibre feeding mechanism on the sliding table into position. The path of the sliding table is controlled by the controller, and the machine can make forward, backward, wire feed and other movements according to the programmed commands. The developed system automatically weaves and feeds natural fibre into the desired structure. The resulting lightweight natural fibre material forms a model with unique architectural quality. The results show that the model is of great value and significance, and it can be used to make the required structure with the desired natural fibre. Additionally, to establish the feasibility of future work focusing on harakeke fibre development in design and construction, the tensile strength of native New Zealand flax fibre (harakeke fibre) was evaluated with a view for use in these load bearing and architectural design applications. Single filament fibres were selected in batches and tensile tested. The longitudinal strength of specimens was established, and the mechanical properties of the fibres were summarised. Comparison of these attributes with existing data was used to determine if the harakeke fibre can be applied usefully in the construction industry. This research is based on the novel concept of architectural design in the construction industry using 3D weaving with natural fibres, in particular harakeke fibres. To achieve this, several related topics are under investigation, such as the need to design an improved feeding system (including hardware and software control), impregnation of fibre and resin (epoxy and polyester) to make preimpregnated (prepreg) fibre/resin filament, adaptive controlled programme and hardware for the required architecture and structure, and properties testing and characterisation. This project is one of the first attempts to develop an automated robot arm system combined with new material, in this case harakeke fibre, and has made a valuable contribution to this field of research

    State of the Art: Small Spacecraft Technology

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    This report provides an overview of the current state-of-the-art of small spacecraft technology, with particular emphasis placed on the state-of-the-art of CubeSat-related technology. It was first commissioned by NASAs Small Spacecraft Technology Program (SSTP) in mid-2013 in response to the rapid growth in interest in using small spacecraft for many types of missions in Earth orbit and beyond, and was revised in mid-2015 and 2018. This work was funded by the Space Technology Mission Directorate (STMD). For the sake of this assessment, small spacecraft are defined to be spacecraft with a mass less than 180 kg. This report provides a summary of the state-of-the-art for each of the following small spacecraft technology domains: Complete Spacecraft, Power, Propulsion, Guidance Navigation and Control, Structures, Materials and Mechanisms, Thermal Control, Command and Data Handling, Communications, Integration, Launch and Deployment, Ground Data Systems and Operations, and Passive Deorbit Devices

    Flexible and Stretchable Electronics

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    Flexible and stretchable electronics are receiving tremendous attention as future electronics due to their flexibility and light weight, especially as applications in wearable electronics. Flexible electronics are usually fabricated on heat sensitive flexible substrates such as plastic, fabric or even paper, while stretchable electronics are usually fabricated from an elastomeric substrate to survive large deformation in their practical application. Therefore, successful fabrication of flexible electronics needs low temperature processable novel materials and a particular processing development because traditional materials and processes are not compatible with flexible/stretchable electronics. Huge technical challenges and opportunities surround these dramatic changes from the perspective of new material design and processing, new fabrication techniques, large deformation mechanics, new application development and so on. Here, we invited talented researchers to join us in this new vital field that holds the potential to reshape our future life, by contributing their words of wisdom from their particular perspective

    Memory hierarchy and data communication in heterogeneous reconfigurable SoCs

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    The miniaturization race in the hardware industry aiming at continuous increasing of transistor density on a die does not bring respective application performance improvements any more. One of the most promising alternatives is to exploit a heterogeneous nature of common applications in hardware. Supported by reconfigurable computation, which has already proved its efficiency in accelerating data intensive applications, this concept promises a breakthrough in contemporary technology development. Memory organization in such heterogeneous reconfigurable architectures becomes very critical. Two primary aspects introduce a sophisticated trade-off. On the one hand, a memory subsystem should provide well organized distributed data structure and guarantee the required data bandwidth. On the other hand, it should hide the heterogeneous hardware structure from the end-user, in order to support feasible high-level programmability of the system. This thesis work explores the heterogeneous reconfigurable hardware architectures and presents possible solutions to cope the problem of memory organization and data structure. By the example of the MORPHEUS heterogeneous platform, the discussion follows the complete design cycle, starting from decision making and justification, until hardware realization. Particular emphasis is made on the methods to support high system performance, meet application requirements, and provide a user-friendly programmer interface. As a result, the research introduces a complete heterogeneous platform enhanced with a hierarchical memory organization, which copes with its task by means of separating computation from communication, providing reconfigurable engines with computation and configuration data, and unification of heterogeneous computational devices using local storage buffers. It is distinguished from the related solutions by distributed data-flow organization, specifically engineered mechanisms to operate with data on local domains, particular communication infrastructure based on Network-on-Chip, and thorough methods to prevent computation and communication stalls. In addition, a novel advanced technique to accelerate memory access was developed and implemented

    An integrated Tissue Engineering approach to Human Bronchial model: Biodegradable Scaffold and Microfluidics Platform

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    L’ingegneria tissutale è la combinazione di cellule, materiali e metodi di ingegneria, insieme con opportuni fattori biochimici e fisico-chimici, volta a migliorare o sostituire le funzioni biologiche di tessuti danneggiati [1, 2]. A tal proposito supporti porosi e sistemi microfluidici sono utilizzati per scopi di ingegneria tissutale. Scaffold polimerici biodegradabili sono stati sfruttati come supporti strutturali per rigenerare vari tessuti quali ossa, cartilagini, nervi, legamenti, pelle e fegato. Una geometria porosa aperta con canali interconnessi è un prerequisito per la crescita cellulare ad alta densità e per un trasporto di nutrienti, ossigeno e prodotti di scarto metabolici. Infatti, una elevata densità cellulare e un efficiente trasporto di massa contribuiscono alla vitalità cellulare, alla proliferazione e alla riabilitazione finale nei tessuti funzionali [3-5]. Una vasta gamma di scaffold biodegradabili con diverse morfologie è stata fabbricata con metodi convenzionali quali lisciviazione di un porogen solido, schiumatura gas, emulsione/ liofilizzazione, espansione di fluido supercritico e tecniche di separazione di fase [6,7]. Le tecniche di separazione di fase più ampiamente adottate sono note con l’acronimo TIPS (Thermally Induced Phase Separation) e DIPS (Diffusion Induced Phase Separation). Più in particolare, la produzione di supporti polimerici e membrane tramite DIPS è stata ampiamente studiata e applicata per un certo numero di sistemi modello. Vari ricercatori hanno studiato sistematicamente la struttura, la porosità e la cristallizzazione del poli (acido L-lattico), miscela di poli (acido L-lattico) / poliuretano e poli (acido L-lattico) / policaprolattone membrane triolo, preparati da etanolo / diossano e bagni di etanolo / acqua coagulazione attraverso la separazione di fase [8-11], trovando interessanti correlazioni tra il comportamento di fase, la cinetica di demixing e la morfologia della membrana risultante. Altri autori hanno dimostrato che le proprietà meccaniche delle schiume sono controllate principalmente dalla pressione del gas, dalle proprietà dei materiali, dai metodi di fabbricazione e dalla geometria della cella. Con questo proposito, sono state determinate le caratteristiche geometriche che influenzano le proprietà meccaniche: numero di cellule aperte, densità relativa, dimensione delle celle e forma delle cellule [12,13]. Affinché uno scaffold sia idoneo per applicazioni di ingegneria tissutale deve fornire: supporto iniziale e localizzazione delle cellule seminate negli appositi spazi, spunti fisici e biologici per l'adesione, migrazione, proliferazione, differenziazione e, infine, la formazione di tessuti e organi [14-16] . Dispositivi di coltura cellulare microfluidici combinano i vantaggi di miniaturizzazione, semplicità di gestione e di osservazione microscopica (in tempo reale). La microfluidica fornisce la possibilità di variare la composizione del terreno di coltura usando generatori di gradiente [17, 18] al fine di creare condizioni di coltura cellulare che sono fisiologicamente più vicine rispetto ai tradizionali sistemi in vitro (velocità di scambio sostanze nutritive, capacità di stimolazioni meccaniche) [19]. I sistemi microfluidici possono essere utilizzati come piattaforme per controllare e gestire analisi di crescita cellulare e del tessuto. In questa tesi, l'attenzione è focalizzata sul processo DIPS, comunemente utilizzato per la produzione di membrane per varie applicazioni e di scaffold per scopi di ingegneria tissutale. Il sistema selezionato in questo lavoro è costituito da acido poli-L-lattico (PLLA), diossano e acqua. Questa soluzione ternaria è stata usata per la produzione di membrane sottili da usare sia come scaffold per l'ingegneria tissutale che come supporto meccanico biodegradabile. La presente tesi è articolata in più fasi. Come primo passo per la caratterizzazione del sistema PLLA-diossano-acqua, un set di parametri sperimentali sono stati caratterizzati al fine di ottenere membrane porose su entrambi le superfici. Una particolare attenzione è stata dedicata alla concentrazione e al numero dei bagni di coagulazione, al tempo di immersione per singolo bagno e all'ambiente di essiccazione. Analisi SEM, DSC e DMA sono state realizzate per caratterizzare la serie di membrane ottenute modificando parametri sperimentali. I risultati sono in linea con quelli disponibili in letteratura per sistemi simili. La seconda fase di questo lavoro, che punta all'applicazione delle membrane sottili, si basa sulla realizzazione di modelli cellulari umani per l'ingegneria tissutale. Due modelli umani sono stati riprodotti: il modello cellulare da NCI-H441 o A549 e il modello di outgrowth da biopsia umana. I due diversi percorsi seguiti in questo lavoro, vale a dire l'indagine sperimentale del modello cellulare e del modello outgrowth sulle membrane di PLLA, sono complementari. La campagna sperimentale è stata principalmente dedicata a valutare e confrontare i modelli realizzati su membrane sottili di PLLA rispetto ai modelli realizzati su membrane standard di polietilene (PE). Analisi di immunocitochimica, TEER (TransEpiteliale Electrical Resistance) ed ELISA sono state impiegate per valutare i risultati ottenuti. Il terzo passo per l'applicazione delle membrane sottili si basa sulla progettazione e sullo sviluppo di dispositivi microfluidici in cui le membrane sono integrate. Tecniche di soft- litografia sono state utilizzate per costruire lo stampo di silicio per la fabbricazione del dispositivo microfluidico. Successivamente sono state sviluppate tecniche di caratterizzazione elettrica per il monitoraggio della crescita dei tessuti. Colture cellulari di A549 sono state utilizzate per settare i principali parametri sperimentali. I risultati sono in linea con quelli disponibili in letteratura per sistemi simili. L'ultima applicazione delle membrane riprodotte in questo lavoro di tesi si basa sul rivestimento di tessuti biologici umani e/o animale per la preparazione di un tessuto ibrido naturale/ sintetico. Il PLLA (Acido Poli-L-lattico) è un polimero biodegradabile, biocompatibile e bioassorbibile il cui prodotto di degradazione è l'acido lattico, ottenuto dal metabolismo anaerobico lattacido. I tessuti decellularizzati (trachee suine) sono state rivestite con membrane di PLLA e testati meccanicamente. Il metodo tecnologico proposto permette: la realizzazione di uno scaffold sintetico-naturali-tridimensionale in grado di sostenere la crescita e la differenziazione delle cellule impiantate; la ripresa delle proprietà meccaniche del tessuto biologico perse durante il processo di decellularizzazione; il supporto meccanico per migliorare e rendere facile il trapianto di tessuti biotecnologici; la protezione contro l’ambiente esterno al fine di mantenere un ambiente asettico quando il tessuto è esposto ad ambienti esterni.Tissue engineering is the use of a combination of cells, engineering and materials methods, together with suitable biochemical and physical-chemical factors to improve or replace biological functions of damage/deficient tissues [1, 2]. With this respect polymeric porous structures and microfluidics systems are used for tissue engineering purposes. Biodegradable polymeric scaffolds have been harnessed as temporal structural supports to regenerate various tissues such as bone, cartilage, nerve, ligament, skin and liver. An open porous geometry with interconnected channels is a prerequisite for high density cell growth as well as for a sustained mass transport of nutrients, oxygen, and metabolic waste; as a matter of fact, a high cell density and efficient mass transport contribute to cell viability, proliferation, and ultimate rehabilitation into functional tissues [3-5]. A wide range of biodegradable scaffolds with different morphologies have been fabricated by conventional methods such as solid porogen leaching, gas foaming, emulsion/ freeze drying, expansion in supercritical fluid and phase separation techniques [6,7]. The most widely adopted phase separation techniques are known with the acronyms TIPS (thermally induced phase separation) and DIPS (diffusion induced phase separation). More specifically, the production of polymeric scaffolds and membranes via DIPS has been widely studied and applied for a number of model systems. Various researchers investigated systematically the structure, porosity and crystallization behaviour of poly(L-lactic acid), blend of poly(L-lactic acid)/polyurethane and poly(L-lactic acid)/ polycaprolactone triol membranes, prepared from ethanol/dioxane and ethanol/water coagulation baths via phase separation [8-11], finding interesting correlations between phase behaviour, kinetics of demixing and the resulting membrane morphology. Other authors showed that mechanical properties of foams are mainly controlled by the gas pressure, material properties, manufacturing methods, and cell geometry. With this respect, the geometrical features influencing the mechanical properties were determined: number of open cells, relative foam density, cell size and cell shape [12,13]. A well designed tissue engineering scaffold should provide initial support to the seeded cells, localise the cells in the appropriate spaces, and provide physical and biological cues for adhesion, migration, proliferation, differentiation and eventually formation of model tissues and organs [14-16]. Microfluidic cell culture platforms combine the advantages of miniaturization and real-time microscopic observation with the ability to pattern cell culture substrates [17] to vary the composition of culture medium over space using gradient generators [18], and to create cell culture conditions that are more physiological than those found in other in vitro systems, in terms of nutrients exchange rates and to unable mechanical stimulation [19]. Microfluidic systems can be used as platforms to control and run cell and tissue growth analysis. In this thesis, the attention is focused on the DIPS process, commonly used for the production of membranes for various applications and scaffolds for tissue engineering purposes. The target system selected in this work is constituted by poly-L-lactic acid (PLLA), dioxane and water. This ternary solution was adopted for the production of both thin membranes scaffolds for tissue engineering and biodegradable mechanical support. As a first step to the characterization of the system PLLA-dioxane-water, sets of experimental parameters were characterized to obtain skinless membrane. A particular attention was paid to coagulation bath concentration, coagulation bath number, immersion time and drying environment. SEM, DSC and DMA analysis were used to characterize the series of thin membranes obtained changing experimental parameters. The results are in line with those available in literature for similar systems. As a second step to the application of thin membranes is based on human cellular models realization for tissue engineering. Two kinds of human model were employed: the cellular model by NCI-H441 and A549. The experimental campaign was mainly dedicated to evaluate and compared the models realized on PLLA thin membranes than models realized on standard polyester (PE) membrane. Immunocytochemical, TEER (TransEpithelial Electrical Resistance) and ELISA were used to evaluate the results obtained. As a third step to the application of thin membranes is based on design and development of a microfluidic devices in which the membranes are integrated. Soft lithography technique is used to build silica mold and electrical characterization technique was development to monitoring the tissue growth. A549 cell was used to set up the most important experimental parameters. The results are in line with those available in literature for similar systems. The last thin membranes application is based on method of coating humans or/and animals decellularized biological tissues with poly-L-lactic acid (PLLA) for the preparation of a natural/synthetic hybrid tissues. Poly-L-lactic acid is a biodegradable, biocompatible, bioresorbable polymer whose degradation product is lactic acid via lactacid anaerobic metabolism. Decellularized tissue is coated with poly-L-lactic acid and foamed. The proposed technological method allows: the realization of a natural/synthetic three-dimensional scaffold capable of supporting growth and differentiation of the cells implanted; the upswing of mechanical property of the biological tissue lost during the decellularization process; the mechanical support to improve and make easy the transplant of the bioengineered tissues; the protection against external environment to keep a aseptic environment when the tissue is exposed to outdoor environments

    Micro/nanofluidic and lab-on-a-chip devices for biomedical applications

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    Micro/Nanofluidic and lab-on-a-chip devices have been increasingly used in biomedical research [1]. Because of their adaptability, feasibility, and cost-efficiency, these devices can revolutionize the future of preclinical technologies. Furthermore, they allow insights into the performance and toxic effects of responsive drug delivery nanocarriers to be obtained, which consequently allow the shortcomings of two/three-dimensional static cultures and animal testing to be overcome and help to reduce drug development costs and time [2–4]. With the constant advancements in biomedical technology, the development of enhanced microfluidic devices has accelerated, and numerous models have been reported. Given the multidisciplinary of this Special Issue (SI), papers on different subjects were published making a total of 14 contributions, 10 original research papers, and 4 review papers. The review paper of Ko et al. [1] provides a comprehensive overview of the significant advancements in engineered organ-on-a-chip research in a general way while in the review presented by Kanabekova and colleagues [2], a thorough analysis of microphysiological platforms used for modeling liver diseases can be found. To get a summary of the numerical models of microfluidic organ-on-a-chip devices developed in recent years, the review presented by Carvalho et al. [5] can be read. On the other hand, Maia et al. [6] report a systematic review of the diagnosis methods developed for COVID-19, providing an overview of the advancements made since the start of the pandemic. In the following, a brief summary of the research papers published in this SI will be presented, with organs-on-a-chip, microfluidic devices for detection, and device optimization having been identified as the main topics.info:eu-repo/semantics/publishedVersio

    Performance Enhancement of Building-Integrated Concentrator Photovoltaic System Using Phase Change Materials

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    Building-integrated Concentrator Photovoltaic (BICPV) technology produces noiseless and pollution free electricity at the point of use. With a potential to contribute immensely to the increasing global need for a sustainable and low carbon energy, the primary challenges such as thermal management of the panels are overwhelming. Although significant progress has been made in the solar cell efficiency increase, the concentrator photovoltaic industry has still to go a long way before it becomes competitive and economically viable. Experiencing great losses in their electrical efficiencies at high temperatures that may eventually lead to permanent degradation over time, affects the market potential severely. With a global PV installed capacity of 303 GW, a nominal 10 °C decrease in their average temperatures could theoretically lead to a 5 % electricity efficiency improvement resulting in 15 GW increase in electricity production worldwide. However, due to a gap in the research knowledge concerning the effectiveness of the available passive thermal regulation techniques both individually and working in tandem, this lucrative potential is yet to be realised. The work presented in this thesis has been focussed on incremental performance improvement of BICPV by developing innovative solutions for passive cooling of the low concentrator based BICPV. Passive cooling approaches are selected as they are generally simpler, more cost-effective and considered more reliable than active cooling. Phase Change Materials (PCM) have been considered as the primary means to achieve this. The design, fabrication and the characterisation of four different types of BIPCV-PCM assemblies are described. The experimental investigations were conducted indoors under the standard test conditions. In general, for all the fabricated and assembled BICPV-PCM systems, the electrical power output showed an increase of 2 %-17 % with the use of PCM depending on the PCM type and irradiance. The occurrence of hot spots due to thermal disequilibrium in the PV has been a cause of high degradation rates for the modules. With the use of PCM, a more uniform temperature within the module could be realised, which has the potential to extend the lifetime of the BICPV in the long-term. Consequentially, this may minimise the intensive energy required for the production of the PV cells and mitigate the associated environmental impacts. Following a parallel secondary approach to the challenge, the design of a micro-finned back plate integrated with a PCM containment has been proposed. This containment was 3D printed to save manufacturing costs and time and for reducing the PCM leakage. An organic PCM dispersed with high thermal conductivity nanomaterial was successfully tested. The cost-benefit analysis indicated that the cost per degree temperature reduction (£/°C) with the sole use of micro-fins was the highest at 1.54, followed by micro-fins + PCM at 0.23 and micro-fins + n-PCM at 0.19. The proposed use of PCM and application of micro-finned surfaces for BICPV heat dissipation in combination with PCM and n-PCM is one the novelties reported in this thesis. In addition, an analytical model for the design of BICPV-PCM system has been presented which is the only existing model to date. The results from the assessment of thermal regulation benefits achieved by introducing micro-finning, PCM and n-PCM into BICPV will provide vital information about their applicability in the future. It may also influence the prospects for how low concentration BICPV systems will be manufactured in the future.The financial support provided jointly by Engineering and Physical Science Research Council, UK (EP/J000345/1 and EP/K03619X/1) and Department of Science and Technology (DST), India is greatly acknowledged
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