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Hilton, Corydon. "Development and Analysis of a Multifunctional Fuel Cell Structure." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29321.
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Multifunctional material systems are systems that contain individual materials or components which are capable of performing multiple functions. The combination of functions into single entities allows for system-level benefits that are not possible through the optimization of subsystems independently. Benefits enabled through multifunctional designs include increased system efficiency through mass and or volume savings as well as part count reductions. Fiber reinforced polymer (FRP) composite materials are lightweight, high-strength materials that can be tailored to achieve a unique set of properties. These characteristics make composites ideal materials for multifunctional designs.
The current research focuses on the production, optimization, and characterization of a multifunctional fuel cell system. This product combines fuel cell technology with composite materials technology to achieve a design that produces electrical power while also providing specific load carrying capability. The study investigates new system designs and new processing techniques, including vacuum assisted resin transfer molding (VARTM) and pultrusion. A metric which allows for the characterization of multifunctional fuel cell systems is developed and applied to three fuel cell designs. This metric uses Frostigâ s Higher Order Theory to analyze the mechanical behavior of the cells while the electrical performance of each device is based on its specific power output. For the cells investigated here, multifunctional efficiencies between 22% and 69% are achieved. The multifunctional efficiency is highly dependent on the transverse pressure applied to the fuel cell components, as this pressure determines ohmic resistances, mass transfer properties, and sealing abilities of the systems. The mechanical pressures at the GDL/Polar Plate interface of a model fuel cell system are explored via experiments with pressure-sensitive film as well as FEA studies, and an optimum structural pressure of approximately 200 psi is identified. Additionally, the effects that concentrated, bending loads have on the electrochemical performance of a model multifunctional cell are explored. The results indicate that one must give generous consideration to the out of plane loads which the fuel cell system will be subjected to (both inherent, structural loads resulting from processing conditions and external, applied loads encountered during operation) in order to achieve optimal multifunctional efficiency.Ph. D.
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Bhatti, Wasim. "Mechanical integration of a PEM fuel cell for a multifunctional aerospace structure." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21513.
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A multifunctional structural polymer electrolyte membrane (PEM) fuel cell was designed, developed and manufactured. The structural fuel cell was designed to represent the rear rib section of an aircraft wing. Custom membrane electrode assemblies (MEA s) were manufactured in house. Each MEA had an active area of 25cm2.The platinum loading on each electrode (anode and cathode) was 0.5mg/cm2. Sandwiched between the electrodes was a Nafion 212 electrolyte membrane. Additional components of the structural fuel included metallic bipolar plates and end plates. Initially all the components were manufactured from aluminium in order for the structural fuel cell to closely represent an aircraft wing rib. However due to corrosion problems the bipolar plate had to be manufactured from marine grade 361L stainless steel with a protective coating system. A number of different protective coating systems were tried with wood nickel strike, followed by a 5μm intermediate coat of silver and a 2μm gold top coat being the most successful. Full fuel cell experimental setup was developed which included balance of plant, data acquisition and control unit, and a mechanical loading assembly. Loads were applied to the structural fuel cells tip to achieve a static deflection of ±7mm and dynamic deflections of ±3mm, ±5mm, and ±7mm. Static and dynamic torsion induced 1° to 5° of twist to the structural fuel cell tip. Polarisation curves were produced for each load case. Finite element analysis was used to determine the structural fuel cell displacement, and stress/strain over the range of mechanical loads. The structural fuel cells peak power performance dropped 3.9% from 5.5 watts to 5.3 watts during static bending and 2% from 6.2 watts to 6.1 watts during static torsion. During dynamic bending (2000 cycles) the structural fuel cell peak power performance dropped 11% from 6.7 watts to 6 watts (3mm deflection at 190N), 23% from 6.3 watts to 4.8 watts (5mm deflection at 270N), and 41% from 7.2 watts to 5 watts (7mm deflection at 350N). During dynamic torsion (2000 cycles) the structural fuel cell peak power performance dropped 16% from 6 watts to 5.1 watt (3° of torsional loading), and 30% from 6.4 watts to 4.3 watts (5° of torsional loading). The simulated (finite element modelling) displacement of -6.6mm (At maximum bending load of 364.95N) was within 9% of the actual measured displacement of -7.2mm at 364.95N. Furthermore the majority of the simulated strain values were within 10% of the actual measured strain for the structural fuel cell.
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CAPOVILLA, GIORGIO. "Development of next generation multifunctional composite structures for CubeSats, pico- and nanosatellites." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971315.
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Moakes, Richard John Asa. "Whey protein micro-particles as multifunctional materials for structure and delivery." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8160/.
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This thesis seeks to augment the understanding of gelled micro-particulate suspensions known as sheared/fluid gels, by investigating the use of dairy proteins (whey, WPI) as the gelling material. The research used a microstructural approach to probe the underlying design principles governing the formation, and subsequent material properties of WPI microgel systems. The work initially focused on preparing suspensions through both thermal and cold-set approaches. By controlling two key processing parameters: shear and gelling rate, it was shown that a range of suspension properties could be produced. In both cases, it was demonstrated that structural characteristics could be controlled, for tailored rheologies. The shear technology was then applied to a more complex system of oil and whey protein, resulting in the formation of microcapsules; as the WPI gelled around the oil droplets in a core-shell model. Again, controllable structural properties were obtained, however, the lipophilic core provided a reservoir for potential delivery. This multi-functional formulation was then investigated under gastro-intestinal conditions, highlighting controllable release as a function of the type of oil used in production. Therefore, the potential use of WPI/WPI-oil micro-particles have been presented as a multi-functional composite for both structure and delivery within food ingredients.
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Ogbomo, Sunny Minister. "Processing, structure property relationships in polymer layer double hydroxide multifunctional nanocomposites." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12174/.
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Dan Beaty (1937-2002) was a prolific composer, pianist, researcher, educator, and writer. His large compositional output included chamber works, choral works, songs, orchestral pieces, electronic music, and keyboard works. Beaty was well versed in traditional Western music as well as the more avant-garde and perplexing idioms of the twentieth century. Beaty's compositions reflect the many fascinating, if not always popular, musical trends of his time. His music encompasses styles from serial to jazz, shows compositional influences from Arnold Schoenberg to Indonesian music, and demonstrates thought-provoking and highly intellectual craftsmanship. This document explores several of Beaty's songs through a discussion of the composer's life and compositional process. Songs included in this document are Three Weeks Songs, October, November, A Sappho Lyric, Love Song, That Night When Joy Began, and War Lyrics. This document was written to accompany the author's DMA Lecture-Recital at the University of North Texas. Unfortunately, Beaty's vocal music was never published and is mostly unknown. One goal of the project was to initiate interest in Beaty's songs. Through this document, Lecture-Recital, and additional performances, considerable strides have been made to bring Beaty's songs to new audiences throughout the United States. In addition, the author has received permission from the Beaty family to publish Dan Beaty's songs.
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Ogbomo, Sunny Minister D'Souza Nandika Anne. "Processing, structure property relationships in polymer layer double hydroxide multifunctional nanocomposites." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12174.
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Mandlekar, Neeraj Kumar. "Integration of wood waste to develop multifunctional fully biobased textile structure." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I062/document.
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Les textiles jouent un rôle important dans notre vie quotidienne. La plupart des fibres textiles et des tissus sont fabriqués à partir de polymères à base de pétrole, des matériaux inflammables et potentiellement dangereux. Afin de conférer le caractère ignifuge aux fibres textiles; entre autres, les composés halogénés sont plus efficaces et largement utilisés pour améliorer le comportement ignifuge des matières textiles. Cependant, en raison de la toxicité des composés halogénés et de l'épuisement progressif des ressources pétrolières, les communautés scientifiques et industrielles sont obligées de trouver des solutions alternatives. Par conséquent, on s’intéresse de plus en plus aux ressources durables, en particulier au développement de systèmes ignifugeants fabriqués à partir de ressources biologiques et respectueux de l’environnement non halogénés. Dans le contexte de l’utilisation de ressources biologiques, une attention particulière a été appelée pour la biomasse. Après la cellulose, la lignine est le deuxième polymère de biomasse le plus abondant et le principal à base d'unités aromatiques. En particulier, la lignine est avantageuse car c’est un coproduit des industries de la pâte à papier et de la fabrication du papier et non une ressource qui nécessite une production spécifique. En fait, sa structure chimique hautement aromatique permet d’améliorer différentes propriétés fonctionnelles telles que la résistance aux UV, l’antioxydant et l’ignifugation des polymères. Récemment, la lignine a fait l’objet d’une grande attention en tant qu’additif retardateur de flamme d'origine biologique en raison de son aptitude élevée à la formation de carbone après la décomposition thermique. Cette capacité de formation de carbone de la lignine en fait un candidat de choix comme source de carbone pour un système intumescent avec un autre additif ignifuge. Lors du chauffage, les matériaux intumescents ignifuges (FR) forment une couche carbonisée cellulaire expansée; agissant comme une barrière physique contre le transfert de chaleur et de masse, qui protège le matériau sous-jacent de l'action du flux de chaleur et de la flamme.Au meilleur de nos connaissances, aucune étude n'a été publiée concernant l'introduction de la lignine en tant que source de carbone dans les structures textiles pour leur conférer des propriétés ignifugeantes. Par conséquent, dans cette étude, la lignine a été introduite dans la structure textile lors de la composition. Cette thèse porte sur le développement de la structure textile ignifuge entièrement biosourcée. Pour atteindre cet objectif, l'approche en plusieurs étapes est adoptée. Dans une première étape, la matrice polymère biosourcée a été sélectionnée pour produire la structure textile et la méthode d’incorporation de la lignine a été étudiée et optimisée. Ensuite, les propriétés ignifuges apportées par la lignine ont été caractérisées et améliorées en ajoutant un additif ignifuge dans les formulations (par exemple, utilisation de sources acides pour développer un système intumescent pouvant améliorer la résistance des textiles au feu). Dans la deuxième phase du projet, la lignine a été combinée à la source d'acide d'origine biologique pour développer une nouvelle génération de structures durables (100% biosourcées) destinées aux marchés du textile. La principale avancée technologique consiste à utiliser et à combiner différents composants biosourcés utilisés dans d'autres industries, telles que l'industrie du plastique, afin de développer des solutions textilesIt has been chosen to study valorization of low-cost industrial lignin as additive in designing the flame retardant (FR) system for polyamide 11 (PA) to develop biobased textile structure. The main focus of this thesis work is to consider lignin as carbon source and introduce in a textile structure in combination with phosphinate salt (FR agent). In the primary study, chemically different industrial lignins were incorporated in PA by extrusion to investigate the charring and fire retardant behaviour of the prepared binary blends. In addition, the introduction of sulphonated lignins significantly reduced the peak of the heat release rate (PHRR) and of the total heat release (THR), and a noticeable increase of the char residue was observed after forced combustion test. In the next approach, lignin was exploited as carbon source in combination with commercially available phosphinate FR (i.e., ZnP and AlP). To achieve this objective, a preliminary study carried out with laboratory grade lignin (LS) combined with ZnP to investigate the thermal stability and fire performance as well as the possible synergy between lignin and ZnP and with the polymer matrix. The results obtained in this study permitted to continue further, the practical implementation of lignin and multifilament production. In the next step, flame retarded blends were developed with direct addition of low-cost industrial lignins (LL and DL) with phosphinate FR. For the systematic understanding, various FR formulations were developed by varying the lignin and FR loading and characterized. Thermal decomposition analysis showed that the presence of lignin decreases the initial decomposition temperature (T5%) due to the decomposition of lignin which starts at a lower temperature region with the evolution of less thermally stable compounds and the maximum decomposition temperature (Tmax) shifts to higher temperature region, at this stage the formation of phenolic, carbonyls, hydrocarbons and CO2 along with phosphinate compounds occurs. Meanwhile, in the condensed phase thermally stable aromatic charred layer is formed because of lignin decomposition and phosphate compounds formation due to the presence of phosphinate metal salt. A higher amount of char residue is obtained when LL combined with ZnP/AlP as compared to the DL and ZnP/AlP blends. It is assumed that, during decomposition of LL, the sulfonate compounds release SO2 and transformed into thermally stable Na2SO4, hence giving rise to the stable char residue. The fire properties were assessed by cone calorimeter tests revealed the combination of lignin and phosphinate FR significantly reduced the PHRR and other fire-related parameters due to the formation of a protective char layer. The presence of lignin not only improve fire retardancy but also reduced the evolution of carbon monoxide (CO). More enhanced fire retardant properties were obtained with LL and ZnP/AlP combination reaches to 10 wt% in ternary blends, which not only promotes char formation but also confer the stability to char in the condensed phase. Furthermore, the most enhanced forced combustion results were obtained with LL and AlP (in particular, PA80-LL10-AlP10). Multifilament yarns were successfully produced for PA-DL-ZnP and PA-LL-ZnP combinations. However, the blends of AlP with lignin were not spinnable because of low compatibility and dispersion level of AlP in the polymer. Optical microscopy and tensile tests were performed to study the physical properties of multifilaments. A double layer (interlock structure) knitted fabrics were developed to evaluate fire behaviour analysis on fabric samples
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Ylianttila, M. (Mari). "Structure-function studies of the peroxisomal multifunctional enzyme type 2 (MFE-2)." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514278968.
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Abstract
Multifunctional enzyme type 2 (MFE-2) catalyses the second and the third reactions in the eukaryotic peroxisomal β-oxidation cycle, which degrades fatty acids by removing a two-carbon unit per each cycle. In addition to the 2-enoyl-CoA hydratase 2 and (3R)-hydroxyacyl-CoA dehydrogenase activities, mammalian MFE-2 has also a sterol carrier protein type 2-like (SCP-2L) domain. In contrast, yeast MFE-2 has two (3R)-hydroxyacyl-CoA dehydrogenases, one 2-enoyl-CoA hydratase 2 and no SCP-2L domain.
The physiological roles of yeast (3R)-hydroxyacyl-CoA dehydrogenases (A and B) were tested by inactivating them in turn by site-directed mutagenesis and testing the complementation of Saccharomyces cerevisiae fox-2 cells (devoid of endogenous MFE-2) with mutated variants of Sc MFE-2. Growth rates were lower for fox-2 cells expressing only a single functional domain than for those expressing the Sc MFE-2. Kinetic studies with purified Candida tropicalis MFE-2 and its mutated variants show that dehydrogenase A catalyzes the reaction more efficiently with the medium- and long-chain substrates than dehydrogenase B, which in turn is the only one active with the short chain fatty acids.
The structural basis of the substrate specificity difference of these two dehydrogenases was solved by X-ray crystallography together with docking studies. Protein engineering was used to produce a stabile, homogenous recombinant protein of C. tropicalis dehydrogenases in one polypeptide. The heterodimeric structure contains the typical fold of the short-chain alcohol dehydrogenase/reductase (SDR) family. Docking studies suggest that dehydrogenase A binds medium chain-length substrates as bended, whereas short chain substrates are dislocated, because they do not reach the hydrophobic contacts needed for anchoring the substrate to the active site, but are instead attracted by L44. Dehydrogenase B has a more shallow binding pocket and thus locates the short chain-length substrates correctly for catalysis. Thus the data provide clues for structural basis of the different substrate specificities.
The molecular basis of the patient mutations of MFE-2 (DBP deficiency) was studied using the recently solved crystal structures of rat (3R)-hydroxyacyl-CoA dehydrogenase, human 2-enoyl-CoA hydratase and SCP-2L. The predicted effect of the mutations on protein structure could in several cases be explained, and these data supported the conclusion that a genotype-phenotype correlation exists for DBP deficiency.
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Sikora, Aneta E. "Structure-function analysis of a multifunctional enzyme using the atomic force microscope." Thesis, University of Portsmouth, 2010. https://researchportal.port.ac.uk/portal/en/theses/structurefunction-analysis-of-a-multifunctional-enzyme-using-the-atomic-force-microscope(fdbd2065-c230-4eba-a7cd-94cbb1bb9e16).html.
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The type I R-M enzyme EcoR124I is a multifunctional, multisubunit molecular motor with the ability to self-assemble. In the presence of hydrophobic compounds, subunit disassembly has been observed leading to the possibility of using the enzyme as a nanoactuator in toxicity biosensors. A better understanding of single molecule interactions between the subunits has been investigated using atomic force microscopy (AFM), a powerful tool for measuring forces and dynamics between single molecules with a picoNewton sensitivity. AFM imaging of DNA fragments with a single recognition binding site for EcoR124I positioned in the middle or at 1/3 of the length of DNA, was used to study the assembled holoenzyme. Reproducible DNA imaging was investigated using divalent cations (Mg2+, Ca2+, Ni2+). The presence of only one EcoR124I holoenzyme bound to DNA was observed, confirming the specificity of binding. Molecular volume (Vm) measurements were used to identify subunits and complexes. The effect of ATP analogues (ATP-γ-S and AMP-pnp) on enzyme stability was also investigated. The addition of ATP, although not novel, confirmed the enzyme activity by showing the ability of the enzyme to translocate. Biotin-avidin interactions were studied using AFM force curves as a model to probe the novel HsdR-MTase system. AFM tips were functionalised using both glutaraldehyde and a PEG linker. In the former, many multiple event force curves were seen, although the final “pull-off” event yielded information on single-molecule or near single-molecule interactions: a single biotin-avidin interaction at 56 ± 13 pN was measured, with further periodic force maxima at 98 ± 15 and 161 ± 3 pN (two and three interactions, respectively). The use of a PEG linker allowed more sensitive measurements to be made, with a single biotin-avidin interaction at 47 ± 9.5 pN and, again, periodic maxima were seen at 93 ± 7 and 143 ± 4 pN. The PEG linker method allowed more single molecules interactions to be measured (ca. 70% of analysed forcedistance curves). Forces between a GST-HsdR(PrrI) motor subunit attached to an AFM tip using a PEG linker and MTase on poly-L-lysine pre-treated mica were studied using dynamic force spectroscopy (DFS). A single barrier in the energy landscape of the complex was found in the dissociation pathway (xdiss) to be located 13.5 Å from the bound state. The value kdiss for the GST-HsdR(PrrI)-MTase complex was calculated to be 0.16 s-1 and the lifetime t(0) of the GST-HsdR(PrrI)-MTase bond was found to be 6.25 s. GST – anti GST antibody interactions and HsdR – anti-GST antibody interactions suggest that forces measured between HsdR and MTase were realistic for the GSTHsdR(PrrI)-MTase complex.
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Dunn, Christopher Thomas 1971. "The design, analysis, construction, and testing of a multifunctional composite satellite structure." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9243.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.Also available online at the MIT Theses Online homepage
Includes bibliographical references (leaves 290-294).
A small space based telescope is being designed by the Charles Stark Draper Laboratory, Inc. in conjunction with MIT. The design goal of this project is to use existing technology to gather ground data from low earth orbit at a minimal cost. A structure was constructed at MIT that allows the satellite to survive launch loads and maintains the optical stability of the satellite. The structure is a double hull design constructed of AS4/3501-6 graphite epoxy with a zero coefficient of thermal expansion lay-up to prevent defocussing of the optics due to thermal loading. The overall design goal at MIT is to construct a space worthy structure. This thesis includes the preliminary design of the inner structure that houses the optics for the telescope. Design of the outer structure, the connections between the inner and the outer structure and detailed design of the inner structure are not included in this work. The analytical techniques used in this project included thermal analyses of structures in various earth orbits, determination of structural requirements from optical performance calculations, designing of near zero Coefficient of Thermal Expansion (CTE) laminates, consideration of manufacturing and material variations in design, strength analysis of composite laminates, and determination of vibration modes and associated frequencies of tubular structures with anisotropic sandwich construction. Experimental work included the building of co-cured honeycomb panels, curved panels, and tubular sections to verify the structure as designed was manufacturable. These efforts culminated in the production of a space-worthy component. Testing was preformed to verify the analysis and design. Testing included flatwise tension testing to verify integrity of the honeycomb bonding, tensile testing to verify stiffness calculations and experimentally determine the failure load for the desired lay-up, and testing to verify the CTE was within acceptable bounds to prevent the optics from defocussing.
by Christopher Thomas Dunn.
S.M.
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ZEMINIANI, ELEONORA. "Sistemi multifunzionali integrati (Integrated multifunctional systems)." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2507790.
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This thesis was born in the context of a research activity conducted by Thales Alenia Space Italia, and called Integrated Multifunctional Systems.
The name is quite self-explanatory: the research is devoted to the study of Multifunctional Systems (MFSs). The work hereafter described addresses MFSs combining thermal, structural, electronic, and control functionalities.
The rationale behind this activity comes from a careful evaluation of mission drivers and constraints for space systems. In the last 30 years, studies have shown that the largest contributors of total spacecraft dry mass are two technology areas: structure and packaged electronics. This information indicates a potentially fruitful area of technology development that would provide significant spacecraft dry mass reduction. Possible interesting areas to be addressed are bus architectures, novel electronic packaging and layout, electronic chassis that also function as structural members, minimization of harness. Moreover, there is increasing interest in the unnoticeable distribution of thermal control and monitoring hardware throughout the system.
The challenge is to meet mission requirements taking into account an integrated design that addresses all areas of structural, electrical, component packages, and thermal elements.
In particular, for this thesis the aim was to identify different ways of combining electrical and thermal control functions with mechanical structures in order to create a multifunctional system able to save mass and volumes, and simplify integration.
The goal of the work was to screen materials and technologies to be used for structural elements, thermal solutions, and integrated electronics, to conceive, design, manufacture, and test suitable prototypes, and to evaluate the application of multidisciplinary design and optimization techniques to this field.
The work has been conducted in close collaboration with Thales Alenia Space Italia S.p.A. (TAS-I), and with the Jet Propulsion Laboratory (JPL)/California Institute of Technology (Caltech). Over a three year timespan, four different demonstrators have been considered: three of them have been developed with TAS-I, and one with JPL.
In chronological order, the first prototype is the Advanced Bread Board (ABB), which is a thermostructural panel built in Carbon/Carbon and equipped with distributed electronics and sensors.
The second prototype was implemented into three different demonstrators, SDA, SDB, and SDC (respectively, STEPS Demonstrator A, B, and C). They consist of an intelligent, modular, flat, and flexible motherboard which has been mounted on an aluminium sandwich panel, a curved aluminium plate, and a layer of Kevlar fabric.
The third prototype is the ROV-E smart skin demonstrator, which is a development of the STEPS motherboard concept, and the fourth prototype is the JPL μRover, which consists of a small 4-wheeled robot made of thermostructural Printed Circuit Boards (PCBs).
The four prototypes represent subsequent steps toward the realization of a multifunctional system where electronics in flex and rigid-flex form is bounded with structure. The goal is to achieve a more distributed architecture equipped with enough intelligence to handle communication, thermal/environmental control, and actuation.
ABB is the first example, where small flat and flex boards with limited intelligence are mounted on a structural substrate with high thermomechanical performances. After the results obtained from ABB, the design flow is ideally split in two branches.
The first research branch keeps on the development of flex electronics as a mean to integrate communication capabilities, health monitoring, signal and power harness on many different support materials: the STEPS demonstrators and the ROV-E smart skin concept are products coming from this approach. The STEPS demonstrators show increased dimensions, expanded capabilities, and higher level of on-board intelligence.
The ROV-E smart skin brings these characteristics to their maximum extent: the design is focused on an extremely flexible board, able to monitor the surrounding structure and environment, able to actuate loads and to take care of signal and power distribution.
On the other hand, the second research branch explores the possibility of using the electronic boards themselves (in rigid-flex configuration) as structural elements: the JPL μRover is the product of this approach. The micro rover is supposed to show the viability of eliminating electronic boxes by transferring all the components on the primary structure, which is therefore made of Printed Circuit Boards based on particular thermostructural materials.
This thesis describes the work conducted for the development of integrated multifunctional systems from 2010 to 2012, and is divided in five main chapters, introduced by a preface. The preface itself presents the topic and scope of the work, and describes the research methodology used during activities. It also describes the structure of the thesis and acknowledges relevant contributions.
The first chapter is dedicated to the literature review. Its goal is to explore the state of the art, to gather and summarize information on activities that have been performed up to now in the field of Multifunctional Systems. These activities are the foundations on which the work described in this thesis has been conceived, and represent the benchmark for the evaluation of achieved results. Therefore, a section is also included which contains a critical analysis of the activities most strictly related to this thesis.
The second chapter presents how the research has been actually conducted, the activities regarding technology study and design, the factual implementation of concepts, the technical description of all different prototypes, and a first glance on results obtained.
The third chapter describes in more detail all the findings, including test results and interpretation of data.
The fourth chapter focuses on analysis and discussion of results and findings, with particular attention to their position in the context of the initial literature review and possible comparison with closest rivals.
The fifth chapter draws conclusions and explains where further work is needed and which activities are going on to bring the multifunctional systems approach from the laboratory to the space vehicle.
To broaden the discussion on given topics, or to give additional information on specific technologies, an appendix has been added.
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Haapalainen, A. (Antti). "Structure-function studies of the mammalian peroxisomal multifunctional enzyme type 2 (MFE-2)." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514268385.
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Abstract
Mammalian peroxisomes contain two parallel multifunctional enzymes (MFE), MFE type 1 and MFE type 2 (MFE-2), which are responsible for the degradation of fatty acids. They both catalyze the second and third reactions of the β-oxidation pathway, but through reciprocal stereochemical courses. MFE-2 possesses (2E)-enoyl-CoA hydratase-2 and (3R)-hydroxyacyl-CoA dehydrogenase activities. In addition, the carboxy-terminal part is similar to the sterol carrier protein type 2 (SCP-2).
The purpose of this work was to study the structure-function relationship of functional domains of mammalian MFE-2 by recombinant DNA technology, enzyme kinetics and X-ray crystallography. The work started with the identification of conserved regions in MFE-2. This information was utilized when dehydrogenase, hydratase-2 and/or SCP-2-like domain were produced as separate recombinant proteins. Subsequently, both dehydrogenase and SCP-2-like domains were crystallized and their crystal structures were solved.
The structure of the dehydrogenase region of rat MFE-2 contains the basic α/β short-chain alcohol dehydrogenase/reductase (SDR) fold and the four-helix bundle at the dimer interface, which is typical of dimeric SDR enzymes. However, the structure has a novel carboxy-terminal domain not seen among the known structures. This domain lines the active site cavity of the neighbouring monomer, reflecting cooperative behaviour within a homodimer.
The monomeric SCP-2-like domain of human MFE-2 has the same fold as rabbit SCP-2. The structure includes a hydrophobic tunnel occupied by an ordered Triton X-100 molecule, demonstrating the ligand-binding site. Compared to the unliganded rabbit SCP-2 structure, the position of the carboxy-terminal helix is different. The movement of this helix in the liganded human SCP-2-like domain resulted in the exposure of a peroxisomal targeting signal, suggesting ligand-assisted protein import into peroxisomes.
The roles of conserved protic residues in the hydratase-2 region of human MFE-2 were studied by mutating them to alanine. In the first step, the ability of mutated variants to utilize oleic acid in vivo was tested with Saccharomyces cerevisiae fox-2 cells (devoid of endogenous MFE-2). Subsequently, in vitro characterization of the mutant enzymes revealed two amino acid residues, Glu366 and Asp510, vital for hydratase-2 activity. The results indicate that the acid-base catalysis is valid for hydratase-2.
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Roberts, Samuel Charles. "An investigation of the feasibility of a spacecraft multifunctional structure using commercial electrochemical cells." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/67387/.
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Multifunctional structures offer the potential for large savings in the mass and cost of spacecraft missions. By combining the functions of one or more subsystems with the primary structure, mass is reduced and internal volume freed up for additional payload, or removed to reduce structural mass. Lithium batteries, increasingly preferred to other power storage solutions, can be employed to produce such structures by incorporating prismatic batteries into structural sandwich panels. Such “powerstructures” can reduce the mass and volume of the power storage subsystem. After reviewing the current work in the field of multifunctional structures, this thesis describes the objective of the research, to examine the usefulness and feasibility of a multifunctional structure based on commercial lithium cells and sandwich structures. The next section presents a study that quantifies the benefits of this technology, showing maximum savings of up to 2% of total mass, and 0.5-1% for common spacecraft designs. The next section describes experimental investigations into the mechanical suitability of commercial PLI cells for use in the multifunctional structure. Firstly, the effect of launch vibration was considered: 15 and 25 grms tests showed no measurable loss in electrical performance. Then, the structural attributes of the cells were measured using a dynamic shear test. The shear modulus of the cells was found to be rather lower than that of an aluminium honeycomb core material. Consideration is then given to the practical implications of a multifunctional structure. The feasibility of manufacturing is assessed through the construction of a trial panel, showing that the cells lose some capacity and suffer an increase in internal resistance in a high-temperature adhesive cure and that a cold-bonding process may thus be preferable. The resultant panel was then vibrated on an electrodynamic shaker to both assess the resilience of the cells and test the reliability of finite element models. These finite element models are then used for a simple optimisation, showing that a welldesigned powerstructure can have structural performance comparable to a conventional design. The final section weighs the benefits of using a multifunctional structure against the potential disadvantages in terms of cost, design time and flexibility, as well as assessing the validity of assumptions made in the work. The conclusion is that a multifunctional structure of this type, whilst not worthwhile for all mission types, could potentially increase the feasibility of short-term spacecraft missions using small satellites (of the order of 100 kg) with large energy storage requirements.
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Bruzzi, Davide. "ALMASat-1, ALMASat-EO and beyond: evolution of structural concepts and technologies towards multifunctional structures for microsatellites." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6999/.
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Multifunctional Structures (MFS) represent one of the most promising disruptive technologies in the space industry. The possibility to merge spacecraft primary and secondary structures as well as attitude control, power management and onboard computing functions is expected to allow for mass, volume and integration effort savings. Additionally, this will bring the modular construction of spacecraft to a whole new level, by making the development and integration of spacecraft modules, or building blocks, leaner, reducing lead times from commissioning to launch from the current 3-6 years down to the order of 10 months, as foreseen by the latest Operationally Responsive Space (ORS) initiatives.
Several basic functionalities have been integrated and tested in specimens of various natures over the last two decades. However, a more integrated, system-level approach was yet to be developed. The activity reported in this thesis was focused on the system-level approach to multifunctional structures for spacecraft, namely in the context of nano- and micro-satellites.
This thesis documents the work undertaken in the context of the MFS program promoted by the European Space Agency under the Technology Readiness Program (TRP): a feasibility study, including specimens manufacturing and testing. The work sequence covered a state of the art review, with particular attention to traditional modular architectures implemented in ALMASat-1 and ALMASat-EO satellites, and requirements definition, followed by the development of a modular multi-purpose nano-spacecraft concept, and finally by the design, integration and testing of integrated MFS specimens.
The approach for the integration of several critical functionalities into nano-spacecraft modules was validated and the overall performance of the system was verified through relevant functional and environmental testing at University of Bologna and University of Southampton laboratories.
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Yan, Haile. "Crystal structure, martensitic transformation crystallography, mechanical and magnetocaloric performance of Ni(Co)MnIn multifunctional alloys." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0105/document.
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Les alliages à base de Ni-Mn-In ont attiré une attention considérable en raison de leurs propriétés multifonctionnelles depuis leur découverte en 2004, telles que l’effet de mémoire de forme métamagnétique (Metamagnetic shape memory effect MMSME), l'effet magnétocalorique (MCE) et l'effet de magnétorésistance (MR). Cependant, certaines connaissances fondamentales sur ces alliages manquent toujours jusqu'à présent, telles que la structure cristalline de la martensite, les caractéristiques cristallographiques de microstructure et de transition magnétostructurale. Dans cette thèse, les caractéristiques cristallographiques, les comportements mécaniques et les propriétés magnétiques des alliages Ni-Mn-In base ont été étudiés théoriquement et expérimentalement. Tout d'abord, les structures cristallines des alliages Ni-Mn-In ont été déterminées avec précision par la méthode de Rietveld dans le cadre de la théorie du superespace. Ensuite, la microstructure de la martensite, notamment l'organisation et l'interface des variantes, ainsi que les caractéristiques cristallographiques de la transformation martensitique, telles que les relations d'orientation (OR), le chemin de déformation de la transformation et la compatibilité géométrique entre l'austénite et la martensite, ont été systématiquement étudiés. Enfin, avec cette connaissance fondamentale sur les alliages Ni-Mn-In, les comportements et les mécanismes de sélection /réarrangement des variantes de martensite sous deux types de stratégies de chargement mécanique, à savoir le chargement à l'état martensitique et le chargement durant la transition structurelle, et les effets du recuit sur l'effet MCE et les pertes d'hystérésis associées ont été explorées. Les principaux résultats sont les suivants. La martensite modulé a une structure cristalline incommensurable avec la structure cristalline 6M et le groupe de superespace I2/m(α0γ)00 qui peut être approximée par un modèle de superstructure de multiplicité 3 dans l'espace à tridimensionnel. La microstructure de martensite est en forme de plaques et auto-organisée en colonies. Chaque colonie a quatre variantes d'orientations distinctes. Le maximum de 6 colonies distinctes et 24 variantes peut être généré à l'intérieur d'un grain austénitique. Bien que jusqu'à 14 types de relations de maclage sont proposées dans le cadre des théories cristallographiques de transformation martensitique, seuls trois types de relations de maclage sont généralement observés, à savoir des macles de type I, type II et composées. Les interfaces des variantes sont définies à l'échelle mésoscopique par leur plan de maclage K1 correspondant. Cependant, à l'échelle atomique, la macle de type I a une interface cohérente, alors que celles de type-II et les macles composées ont des interfaces étagées. Les deux relations d'orientations K-S et Pitsch sont appropriés pour décrire la correspondance de réseau entre austénite et martensite dans les alliages Ni-Mn-In. Cependant, le chemin de déformation lié à la relation de Pitsch est mis en évidence pour être efficace pour la déformation de la structure. Avec le chemin de transformation déterminé, le mécanisme sous-jacent de l'organisation des variantes est révélé. À travers la transformation martensitique, en dépit de l'existence d'une relativement large couche contrainte (de l'ordre de 20 nm), le plan d'habitat est bordé par une variante de martensite simple avec l'austénite plutôt que la structure généralement observée "en sandwich", ce qui suggère une relativement bonne compatibilité géométrique entre les phases correspondantes. Pour le chargement en compression à l'état martensitique, l'arrangement des variantes est réalisé par des processus de démaclage. Il est démontré que l'état de variante unique dans certaines colonies pourrait être obtenu lorsque l'orientation de chargement est située dans la zone de Facteur de Schmid (SF) positif commune pour les trois systèmes de démaclage. [...]Ni-Mn-In based alloys have attracted considerable attention due to their multifunctional properties since its discovery in 2004, such as metamagnetic shape memory effect (MMSME), magnetocaloric effect (MCE) and magnetoresistance (MR) effect. However, some fundenmental knowledge on these alloys is still missing until now, such as crystal structure of martensite, crystallographic features of microstructure and magnetostructural transition. In this dissertation, the crystallographic features, mechanical behaviors and magnetic properties of Ni-Mn-In based alloys were studied theoretically and experimentally. First, the crystal structures of Ni-Mn-In alloys were accurately determined by Rietveld method in the frame of superspace theory (Chapter 3). Then, the microstructure of martensite (Chapter 4), such as variant organization and interface structure, and the crystallographic features of martensitic transformation, such as orientation relationship (OR), transformation strain path and geometrical compatibility between austenite and martensite, were systematically studied (Chapter 5). Finally, with this fundamental knowledge on Ni-Mn-In alloys, the behaviors and mechanisms of martensite variant rearrangement/ selection under two kinds of mechanical loading strategies, i.e. loading at martensite state and loading across the structural transition, and the effects of annealing on MCE and its related hysteresis loss were explored (Chapter 6). The main results are as follows. The modulated martensite has an incommensurate 6M crystal structure with superspace group I2/m(α0γ)00 that can be approximated by a three-fold superstructure model in the three-dimensional space. The microstructure of martensite is in plate shape and self-organized in colonies. Each colony has four distinct orientation variants. The maximum of 6 distinct colonies and 24 variants can be generated within one austenite grain. Although as many as 14 kinds of twin relations are suggested in the frame of crystallographic theories of martensitic transformation, only three types of twin relations are generally detected, i.e. type-I, type-II and compound twin. Variant interfaces are defined by their corresponding twinning plane K1 at mesoscopic scale. However, at atomic scale, the type-I twin has a coherent interface, whereas type-II and compound twins have “stepped” interfaces. Both the K-S and Pitsch ORs are appropriate to describe the lattice correspondence between austenite and martensite in Ni-Mn-In alloys. However, the strain path related to the Pitsch relation is evidenced to be the effective for the structural distortion. With the determined transformation path, the underlying mechanism of variant organization is revealed. Across the martensitic transformation, despite the existence of a relative wide stressed layer (around 20 nm), the habit plane is bordered by single martensite variant with austenite rather than the generally observed “sandwich-like” structure, implying a relative good geometrical compatibility between the corresponding phases. For compressive loading at martensite, variant arrangement is realized by the detwinning process. It is evidenced that a single variant state in some colonies can be obtained when the loading orientation is located in the common positive Schmid factor (SF) zone of the three detwinning systems. For loading across the structural transition, the prestrain is obtained by variant selection in which the number of colonies is significantly reduced and the variant organization within colony is greatly changed. The SF for transformation strain path is introduced to evaluate the possible selection of variants. Heat treatment can significantly enhance the magnetic entropy change ΔSM but simultaneously increase the magnetic hysteresis loss. For ΔSM, the chemical ordered degree should play a prominent role [...]
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Jain, Tanmay. "Design, Characterization, and Structure - Property Relationships of Multifunctional Polyesters for Extrusion-Based Direct-Write 3D Printing." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1586874036561737.
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Kiema, T. R. (Tiila-Riikka). "Studies on the peroxisomal multifunctional enzyme type-1:domain structure with special reference to the hydratase/isomerase fold." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514265777.
Full textAbstract:
Abstract
The peroxisomal multifunctional enzyme type-1 (perMFE-1) is a monomeric
protein
of β-oxidation possessing 2-enoyl-CoA hydratase-1,
Δ3-Δ 2-enoyl-CoA
isomerase, and (3S)-hydroxyacyl-CoA dehydrogenase activities.
The amino-terminal part of perMFE-1 shows sequence similarity to mitochondrial
2-enoyl-CoA hydratases (ECH-1) and Δ3-Δ
2-enoyl-CoA isomerases, and belongs to the
hydratase/isomerase superfamily. Family members with known structures are either
homotrimers or homohexamers. The purpose of this work was to elucidate the
structure-function relationship of the rat perMFE-1 with special reference to the
hydratase/isomerase fold.
The structural adaptations required for binding of a long chain fatty acyl-CoA were
studied with rat ECH-1 via co-crystallization with octanoyl-CoA. The crystal
structure revealed that the long chain fatty acyl-CoA is bound in an extended
conformation. This is possible because, a flexible loop moves aside and opens a
tunnel, which traverses the subunit from the solvent space to the intertrimer
space.
Structural and enzymological studies have shown the importance of Glu144 and
Glu164 for the catalysis by ECH-1. In the present work the enzymological
properties of Glu144Ala and Glu164Ala variants of ECH-1 were studied. The
catalytic activity of hydration was reduced about 2000-fold. It was also
demonstrated that rat ECH-1 is capable of catalyzing isomerization. The
replacement of Glu164 with alanine reduced the isomerase activity 1000-fold,
confirming the role of Glu164 in both the hydratase and isomerase reactions. The
structural factors favoring the hydratase over the isomerase reaction were
addressed studying the enzymological properties of the Gln162Ala, Gln162Met, and
Gln162Leu variants. These mutants had similar enzymatic properties to wild type,
thus the catalytic function of the Glu164 side chain in the hydratase and
isomerase reaction does not depend on interaction with the Gln162 side chain.
The perMFE-1 was divided into five functional domains based on amino acid
sequence comparisons with the homologous proteins with known structures. Deletion
variants of perMFE-1 showed that the folding of an enzymatically active
amino-terminal hydratase/isomerase domain requires stabilizing interactions from
the two carboxy-terminal domains of perMFE-1. The last carboxy-terminal domain is
also required for the folding of the dehydrogenase part of perMFE-1. The
dehydrogenase part of perMFE-1 was crystallized.
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Friedemann, Ariane [Verfasser], Thorsten [Akademischer Betreuer] Gesing, Günter [Gutachter] Schmitt, and Herbert [Gutachter] Juling. "Preparation and structure elucidation of multifunctional porous TiO2 surfaces by means of plasma electrolytic oxidation / Ariane Friedemann ; Gutachter: Günter Schmitt, Herbert Juling ; Betreuer: Thorsten Gesing." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1160030588/34.
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Vashchuk, Alina. "Synthèse, structure et propriétés de polycyanurates réticulés et de matériaux nanoporeux générés en utilisant des liquides ioniques." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC0046/document.
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Cette thèse de doctorat aborde de nouvelles conceptions de films à base de résines d’ester de cyanate (CER) en présence de liquides ioniques (LIs) en tant qu'agents multifonctionnels : catalyseurs, agents de modification réactifs, renforts ou agents porogènes. Les liquides ioniques de structures et de concentrations variables accélèrent de manière significative la polycyclotrimérisation du dicyanate d’ester de bisphenol E, en l'absence de tout solvant organique supplémentaire ou additif. Les réseaux de polycyanurates resultants dopés avec des liquides ioniques aprotiques peuvent constituer des matériaux prometteurs pour la production de structures photosensibles. De tels systèmes nanocomposites permettent la séparation, larécupération et le recyclage aisés des LIs par simple extraction, ce qui permet finalement l'obtention de films nanoporeux thermostables. Les caractéristiques de la porosité de ces matériaux dépendent de la concentration des LIs dans les précurseurs CERs. Les LIs protoniques contenant des groupements fonctionnels >NH et -OH, indépendamment de leurmasse molaire, de la structure chimique du cation et de l'anion, sont incorporés chimiquement dans le réseau polycyanurate. Ainsi, les matériaux hybrides obtenus avec des fragments de liquides ioniques pourraient fournir d’excellents candidats pour des recherches futures sur les ionomères et les nanocompositesThis PhD thesis addresses new designs of cyanate ester resin (CER) films in the presence of ionic liquids as multifunctional agents: catalysts, reactive modifiers, fillers or porogens. It should be emphasized that ionic liquids (ILs) of varying structures and concentrations significantly accelerate the polycyclotrimerization of dicyanate ester of bisphenol E, in the absence of any additional organic solvent or additive. The resulting polycyanurate networks doped with aprotic ionic liquids can be promising materials for producing photosensitive structures. Such nanocomposite systems allow for easier separation, recovery, and recycling of ILs by mere extraction, which eventually affords thermally stable nanoporous films. The porosity features of these materials depend on the concentration of ILs in the CER precursors.Protic ILs containing functional >NH and -OH groups, regardless of molar mass, chemical structure of cation and anion, chemically incorporate into the polycyanurate network, thus the resulting hybrid materials with fragments of ionic liquids could provide excellent candidates for future research in ionomers and nanocomposites
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Simões, Fábio José Ferreira. "Novas centralidades multifuncionais na frente ribeirinha do Seixal. Intervencões urbanísticas de suporte e consolidação a redes ecológicas de âmbito metropolitano." Master's thesis, Faculdade de Arquitetura de Lisboa, 2012. http://hdl.handle.net/10400.5/5796.
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Beckman, Lisa. "Grönytans betydelse i Sundbybergs stad : ur ett planerarperspektiv och ett invånarperspektiv." Thesis, Umeå universitet, Institutionen för geografi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-172132.
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The densification of cities in Sweden often result in loss of green space and puts the beneficial values of urban green space under risk. Especially affected are the inhabitants residing in the city core. Through a qualitative case study of Sundbyberg city, this study aims to explore which features of green spaces that becomes important for residents in a city undergoing fast densification. As well as how the needs are answered from a planning perspective. In order to illustrate both perspectives, the study consists of interviews with planners and residents. The results of the study show that the few green spaces in the city core in large have been compensated with small spaces working as multifunctional places. One example of a multifunctional place is a pocket park. This, planners and residents show both a positive and negative view on. The benefits are simply about that it is needed. The disadvantages raised are mainly about the feelings of those places as private and closed space for some people, although these places origins as open space. The study shows that many similarities prevail between the planners and residents views on the different importance’s of the city’s green spaces. It also shows that there is a discrepancy between the residents experienced needs of green spaces and the planner’s vision of the citys future development. While the residents seem to want more quiet places and places for spontaneous activities, especially to meet the needs of elderly and young. The planner’s visions of the citys development seem to go more towards creating small, to some extent green, safe places which connects different parts of the city.
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Ali, Samer. "Concept innovant d'échangeur/réacteur multifonctionnel par contrôle dynamique passif par générateurs de vorticité flexibles." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0034/document.
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Le but de cette étude est d’étudier l’utilisation d’interactions fluide-structure (FSI) pour améliorer le transfert de chaleur et les performances de mélange dans des échangeurs-réacteurs multifonctionnels, et d’évaluer des configurations pour lesquelles l’objectif est de produire et de maintenir un régime dynamique auto-entretenu d’oscillations des générateurs de tourbillons flexibles. Dans un premier temps, deux études numériques ont été réalisées pour des écoulements laminaires bidimensionnels. Les résultats montrent qu’un minimum de trois générateurs de tourbillons alternés est nécessaire pour produire une instabilité qui engendre les oscillations de larges amplitudes. L’ajout de deux promoteurs coplanaires en amont déstabilise l’écoulement en créant des forces périodiques agissant sur les générateurs de tourbillons en aval. Il en résulte une augmentation de la vitesse réduite qui impose un blocage en fréquence des oscillations des générateurs de tourbillons en aval. Dans cette configuration, des oscillations de larges amplitudes sont obtenues pour uniquement deux générateurs de tourbillons en aval. Les oscillations des générateurs de tourbillons produisent une vorticité intense qui a une incidence positive que le transfert de chaleur et sur le mélange. Dans un second temps, une configuration tridimensionnelle HEV incluant des générateurs de tourbillons trapézoïdaux flexibles orientés a 45◦ vers l’amont est étudiée par simulations numériques. Une analyse FFT réalisée sur les coefficients issus d’une analyse POD montre un pic fréquentiel correspondant aux formations et lâchers tourbillonnaires périodiques. Cette fréquence dominante correspond bien au mode propre d’oscillation des générateurs de tourbillons et engendre ainsi de larges amplitudes d’oscillationsThe aim of this study is to investigate the use of fluid-structure interaction (FSI) to improve heat transfer and mixing performances in multi-functional heat exchangers/reactors, and to evaluate configuration designs where the main target is to produce and maintain self-sustained oscillations of flexible vortex generators. At first, two dimensional laminar flow studies are numerically investigated. The results show that a minimum of three alternating flaps is needed to produce an instability that leads to large displacement oscillations. However, the introduction of two co-planar flaps upstream destabilizes the flow by creating periodic forces that act on the alternating downstream flaps. Hence, this results in artificially increasing the reduced velocity that will induce the alternating flaps to be in a lock-in state. Thus in this case, large displacement amplitudes are created with two alternating flaps only. The free flaps oscillations produce vortices of higher strength which have a positive impact on heat transfer and mixing. Secondly, a three dimensional HEV configuration with flexible trapezoidal vortex generators inclined with an angle of 45◦ with respect to the wall and reversed opposite to the flow direction is numerically investigated. Fast Fourier Transformation is applied on the temporal variation of the Proper Orthogonal Decomposition (POD) coefficientswhich displays a dominant peak in the flow and corresponds to the vortices periodic formation and detachment. This dominant frequency synchronizes well with the structural oscillation frequency and the fundamental frequency of the tabs reaching a lock-in state and leading to large oscillation amplitudes
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Seifert, David Ryan. "Topology Optimization of Multifunctional Nanocomposite Structures." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/86195.
Full textAbstract:
This thesis presents the design of multifunctional structures through the optimal placement
of nanomaterial additives. Varying the concentration of Carbon Nanotubes (CNTs) in a
polymer matrix affects its local effective properties, including mechanical stiffness, electrical
conductivity, and piezoresistivity. These local properties in turn drive global multifunctional
performance objectives. A topology optimization algorithm determines the optimal distribution
of CNTs within an epoxy matrix in an effort to design a set of structures that are
capable of performing some combination of mechanical, electrical, or peizoresistive functions.
A Pareto-Based Restart Method is introduced and may be used within a multi-start gradient
based optimization to obtain well defined multiobjective Pareto Fronts. A linear design
variable filter is used to limit the influence of checkerboarding. The algorithm is presented
and applied to the design of beam cross-sections and 2D plane stress structures. It is shown
that tailoring the location of even a small amount of CNT (as low as 2 percent and as high as
10 percent, by volume) can have significant impact on stiffness, electrical conductivity, and
strain-sensing performance. Stiffness is maximized by placing high concentrations of CNT
in locations that either maximize the bending rigidity or minimize stress concentrations.
Electrical conductivity is maximized by the formation of highly conductive paths between
electrodes. Strain-sensing is maximized via location of percolation volume fractions of CNTs
in high strain areas, manipulation of the strain field to increase the strain magnitude in these
areas, and by avoiding negative contributions of piezoresistivity from areas with differing net
signed strains. It is shown that the location of the electrodes can affect sensing performance.
A surrogate model for simultaneous optimization of electrode and topology is introduced
and used to optimize a 2D plane stress structure. This results in a significant increase in
sensing performance when compared to the fixed-electrode topology optimization.Ph. D.
This dissertation presents a method that allows for the best placement of a limited amount of filler material within a base matrix material to form an optimal composite structure. Adding filler material, in this case Carbon Nanotubes, can change the effective behavior of the composite structure, enhancing the capabilities of the base matrix material by adding structural stiffness, electrical conductivity, and even the ability for the structure to measure its own strains. The degree to which these changes occur is dependent on the amount of filler material present in any given subsection of the structure. The method then is focused on determining how much of the filler to place in different subsections of the structure to maximize several measures of performance. These measures pertain to structural performance, electrical conductivity, and the structure’s ability to sense strains. Steps are taken within the method to remove non-physical designs and also to find the overall best design, called the global minima. The method is applied to several test structures of varying complexity, and it is shown that the optimization method can heavily influence performance by tailoring the filler material distribution. Further electrical and sensing performance gains can be obtained by properly selecting where the electrodes are located on the structure. This is demonstrated by including electrode placement in the design method along with the filler distribution.
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Chillara, Venkata Siva Chaithanya. "Multifunctional Laminated Composites for Morphing Structures." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524104865278235.
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Ognibene, Giulia. "Multifunctional nanocomposites obtained by hierarchical structures." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3980.
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Il presente lavoro è focalizzato sullo sviluppo di nanocompositi multifunzionali innovativi basati sull'uso di una struttura gerarchica. A questo scopo, nanofibre polimeriche sono state prodotte per electrospinning. Questo processo utilizza un' alta tensione (circa il 10-20 kV) per caricare elettricamente una soluzione polimerica per la produzione di fibre ultra-sottili. Due diverse applicazioni sono stati proposte per le membrane termoplastiche ottenute. Nella prima, esse sono state utilizzate per fabbricare laminati compositi tenacizzati e nanorinforzati (utilizzando MWCNT) mediante Resin Transfer Molding (RTM) e altre tecniche di infusione. Mentre nella seconda applicazione, tali membrane sono state modificate con nanoparticelle inorganiche e utilizzate come membrane attive per filtrazione dell'acqua.
La necessità di tenacizzare materiali compositi si pone perché essi sono soggetti a delaminazione lungo piani interlaminari. La soluzione proposta a questo problema è stato l'uso di nanofibre che possono essere abbastanza piccole da rinforzare regioni della matrice che si trovano tra strati adiacenti del laminato. A questo scopo sono stati elettrofilati diversi polimeri e sono stati utilizzati come tenacizzanti in laminati compositi. La caratterizzazione di questi laminati, modificati con nanofibre, mostra proprietà termo-meccaniche simili a quelle dei sistemi ottenuti utilizzando la procedura standard. Inoltre, al fine di conferire altre funzionalità quali resistenza al fuoco, lightining-strike, auto-sensing, ecc al composito, sistemi di resine epossidiche con nanocariche sono stati studiati e caratterizzati.
Parlando di membrane per la filtrazione dell'acqua, attualmente, membrane polimeriche sono per lo più utilizzate per applicazioni di filtraggio grazie alle loro buone proprietà e bassi costi rispetto alle membrane inorganiche. Di conseguenza, i meccanismi di filtrazione di queste membrane si basano principalmente sugli effetti meccanici come setacciatura, quindi nessuna rimozione chimica delle sostanze tossiche può essere realizzata, questo porta ad effetti di fouling che limitano le prestazioni della membrana. L'idea è stata quella di sviluppare le membrane attive per il filtraggio dell'acqua, caratterizzate da un effetto combinato, setacciatura, proprietà foto-catalitiche e proprietà antibatteriche. A questo scopo, nanofili di ZnO cristallino sono stati cresciuti con un processo chimico da un bagno di deposizione sulle fibre PES ES. Le membrane ibride ottenute mostrano una buona attività fotocatalitica. Inoltre, membrane di PES antibatteriche sono state ottenute da un procedimento one step a partire da una soluzione polimerica con nanoparticelle d'argento precursori. La conversione da precursori argento a nanoparticelle di argento è confermata dalla spettroscopia UV-vis.
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Foster, James A. "Thermal management of multifunctional spacecraft power structures." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/181505/.
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Schwingshackl, Christoph Wolfgang. "Dynamic behaviour of inhomogeneous multifunctional power structures." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/52007/.
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Li, Yingjie. "Structures, properties and applications of multifunctional lignin nanofibres." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54038.
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This study explored the feasibility of creating multifunctional lignin materials in nanofibre form to establish a material platform for the development of value-added products. Specifically, softwood kraft lignin was electrospun, thermostabilized and carbonized into carbon nanofibres. Subsequently, functionalization of lignin based carbon nanofibres were conducted by (1) designing lignin-based composite carbon nanofibre; (2) preparing architecturally-designed lignin-based nanofibres and (3) preparing architecturally-designed lignin-based composite nanofibres. Examples of the advanced applications of the functionalized lignin based nanofibres were demonstrated such as electromagnetic interference shielding, energy storage and actuator. Flexible composite carbon nanofibres were embedded with functional fillers e.g. flexible electromagnetic lignin carbon nanofibres embedded with magnetic nanoparticles was developed. The amorphous structure of lignin and the addition of functional fillers impart the mechanical flexibility to lignin carbon nanofibre mats. By combining the magnetic permeability of magnetic nanoparticles and the electrical conductivity of lignin carbon nanofibre, flexible multifunctional lignin composite carbon nanofibres were created. Electromagnetic shielding effectiveness (SE) of lignin-based carbon nanofibres was comparable to that of the petroleum-based (such as polyacrylonitrile (PAN)-based) nanofibres. The feasibility of using above flexible composite carbon nanofibres from lignin as the lithium ion battery anode was demonstrated. This anode is free-standing, binder-free and mechanically flexible mats. Using lignin nanofibres electrodes and solid electrolytes, flexible solid-state lithium ion batteries were successfully assembled and characterized. Moreover, functions were added to electrospun lignin nanofibres by developing architecturally-designed lignin based thermostabilized nanofibres. A unique actuating phenomenon in thermostabilized lignin nanofibres was observed. It exhibits fast, reversible and dramatic mechanical deformation and recovery in response to environmental moisture gradient at milliseconds level. The actuation mechanism was investigated at the molecular level, and fibre assembly level. In summary, this study demonstrated that renewable biomaterials such as lignin has the potential for adding value through multifunctionalization in nanofibres form, thus creating a promising material platform for petroleum free feedstock for advanced applications.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Palma, Giuseppina <1989>. "Numerical modelling and structural optimization of multifunctional maritime structures aimed to protect harbours and produce energy." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amsdottorato.unibo.it/9192/1/PhD_Palma.pdf.
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The main objective of this PhD thesis is to optimize a specific multifunctional maritime structure for harbour protection and energy production, named Overtopping Breakwater for Energy Conversion (OBREC), developed by the team of the University of Campania. This device is provided with a sloping plate followed by a unique reservoir, which is linked with the machine room (where the energy conversion occurs) by means of a pipe passing through the crown wall, provided with a parapet on top of it. Therefore, the potential energy of the overtopping waves, collected inside the reservoir located above the still water level, is then converted by means of low – head turbines.
In order to improve the understanding of the wave – structure interactions with OBREC, several methodologies have been used and combined together:
i. analysis of recent experimental campaigns on wave overtopping discharges and pressures at the crown wall on small – scale OBREC cross sections, carried out in other laboratories by the team of the University of Campania;
ii. new experiments on cross sections similar to the OBREC device, planned and carried out in the hydraulic lab at the University of Bologna in the framework of this PhD work; iii. numerical modelling with a 1 – phase incompressible fluid model IH – 2VOF, developed by the University of Cantabria, and with a 2 – phase incompressible fluid model OpenFOAM, both available from the literature;
iv. numerical modelling with a new 2 – phase compressible fluid model developed in the OpenFOAM environment within this PhD work;
v. analysis of the data gained from the monitoring of the OBREC prototype installation.
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Vaňková, Ivana. "Polyfunkční dům." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265651.
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This master thesis deals with study of area, which is intended for construction of apartments building and public facilities. Four building are projected with visually connection by a covered parking place. There are three apartments building and one multifunctional building. The aim of this master thesis is elaboration of project documentation for the implementation of new multifunctional house in the area of the city Uherský Brod. In the first floor is designed café, which has its own entrance. In the second part of the floor is household equipment and utility room, which also has a separate entrance from outside. In the second to fourth floor is ten housing units of different sizes. The object is located on a gently sloping land in the northern part of Uherský Brod in the new city district called “Nad Zámkem”. Wall construction is designed from Porotherm elements. Ceiling construction is monolithic reinforced concrete. Roofing is solved by single-flat roof. The drawing part of this master thesis is processed in AutoCAD.
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Fan, Xiaolei. "Selective catalytic hydrogenation in a structured compact multifunctional reactor." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519009.
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Selective hydrogenation is an important class of chemical reactions for the production of speciality chemicals, pharmaceuticals and petrochemicals. The challenges in this type of reactions are to control selectivity in hydrogenation of poly-functional molecules, and avoid the possible risk of reaction runaway due to the high exothermisity. In this project the fundamentals of liquid-phase hydrogenation reactions in a structured compact multifunctional reactor were investigated. This technology represents an advance over the existing hydrogenation technologies because it exploits the effects of reduced characteristic paths of mass and heat transfer, attained in compact reactor architecture with mm-scale reaction channels and integrated static mixers and micro-heat exchangers. Catalysts based on mesoporous synthetic carbons were developed especially for preparing micro-packed beds in the compact reactor. The investigation resulted in fundamental information on reactor performance for selected model reactions, heat transfer efficiency of the integrated micro-heat exchangers, development of continuous tandem reaction, and evaluation of developed catalysts for hydrogenation and hydrodehalogenation reactions under the continuous flow conditions being used. The results demonstrate that the structured compact multifunctional reactor might be a promising technology to transfer conventional heterogeneous catalysis to flow regime.
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Narayanan, Vindhya. "Non-equilibrium Thermomechanics of Multifunctional Energetic Structural Materials." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7570.
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Shock waves create a unique environment of high pressure, high temperature and high strain-rates. It has been observed that chemical reactions that occur in this regime are exothermic and can lead to the synthesis of new materials that are not possible under other conditions. The exothermic reaction is used in the development of binary energetic materials. These materials are of significant interest to the energetic materials community because of its capability of releasing high heat content during a chemical reaction and the relative insensitivity of these types of energetic materials. Synthesis of these energetic materials, at nano grain sizes with structural reinforcements, provides an opportunity to develop a dual functional material with both strength and energetic characteristics.
Shock-induced chemical reactions pose challenges in experiment and instrumentation. This thesis is addressed to the theoretical development of constitutive models of shock-induced chemical reactions in energetic composites, formulated in the framework of non-equilibrium thermodynamics and mixture theories, in a continuum scale. Transition state-based chemical reaction models are introduced and incorporated with the conservation equations that can be used to calculate and simulate the shock-induced reaction process. The energy that should be supplied to reach the transition state has been theoretically modeled by considering both the pore collapse mechanism and the plastic flow with increasing yield stress behind the shock wave. A non-equilibrium thermodynamics framework and the associated evolution equations are introduced to account for time delays that are observed in the experiments of shock-induced or assisted chemical reactions. An appropriate representation of the particle size effects is introduced by modifying the initial energy state of the reactants. Numerical results are presented for shock-induced reactions of mixtures of Al, Fe2O3 and Ni, Al with epoxy as the binder.
The theoretical model, in the continuum scale, requires parameters that should be experimentally determined. The experimental characterization has many challenges in measurement and development of nano instrumentation. An alternate approach to determine these parameters is through ab-initio calculations. Thus, this thesis has initiated ab-initio molecular dynamics studies of shock-induced chemical reactions. Specifically, the case of thermal initiation of chemical reactions in aluminum and nickel is considered.
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Martínek, David. "Nosná konstrukce polyfunkčního domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372151.
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Master´s thesis is based on analysis and design of a load-bearing structure of multifunctional house. The main load-bearing elements in the vertical direction are the monolithic reinforced walls and the main load-bearing elements in the horizontal direction are monolithic reinforced concrete plates. The connection of individual floors is made of monolithic reinforced concrete staircases. The foundation of the building is realized through a system of strips foundation. Design drawings are made to selected elements of the structure.
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Song, Yi. "Multifunctional Composites Using Carbon Nanotube Fiber Materials." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353156345.
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Amirkhizi, Alireza Vakil. "Multifunctional composites and structures with integrated mechanical and electromagnetic properties." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237550.
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Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed December 12, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Berglin, Lena. "Interactive Textile Structures : Creating Multifunctional Textiles based on Smart Materials." Doctoral thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3490.
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Textiles of today are materials with applications in almost all our activities. We wear clothes all the time and we are surrounded with textiles in almost all our environments. The integration of multifunctional values in such a common material has become a special area of interest in recent years. Smart Textile represents the next generation of textiles anticipated for use in several fashion, furnishing and technical textile applications. The term smart is used to refer to materials that sense and respond in a pre-defined manner to environmental stimuli. The degree of smartness varies and it is possible to enhance the intelligence further by combining these materials with a controlling unit, for example a microprocessor. As an interdisciplinary area Smart Textile includes design spaces from several areas; the textile design space, the information technology design space and the design space of material science. This thesis addresses how Smart Textiles affect the textile design space; how the introduction of smart materials and information technology affects the creation of future textile products. The aim is to explore the convergence between textiles, smart materials and information technology and to contribute to providing a basis for future research in this area. The research method is based on a series of interlinked experiments designed through the research questions and the research objects. The experiments are separated into two different sections: interactive textile structures and health monitoring. The result is a series of basic methods for how interactive textile structures are created and a general system for health monitoring. Furthermore the result consists of a new design space, advanced textile design. In advanced textile design the focus is set on the relation between the different natures of a textile object: its physical structure and its structure in the context of design and use.
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Ball, Jeffrey Craig. "Design and analysis of multifunctional composite structures for nano-satellites." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2572.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.The aim of this thesis is to investigate the applications of multifunctional compos- ite (MFC) technology to nano-satellite structures and to produce a working concept design, which can be implemented on future Cube-Satellites (CubeSats). MFC tech- nologies can be used to optimise the performance of the satellite structure in terms of mass, volume and the protection it provides. The optimisation of the structure will allow further room for other sub-systems to be expanded and greater payload allowance. An extensive literature view of existing applications of MFC materials has been conducted, along with the analysis of a MFC CubeSat structural design account- ing for the environmental conditions in space and well-known design practices used in the space industry. Numerical analysis data has been supported by empirical analysis that was done where possible on the concept material and structure. The ndings indicate that the MFC technology shows an improvement over the conventional alu- minium structures that are currently being used. Improvements in rigidity, mass and internal volume were observed. Additional functions that the MFC structure o ers include electrical circuitry and connections through the material itself, as well as an increase electromagnetic shielding capability through the use of carbon- bre composite materials. Empirical data collected on the MFC samples also show good support for the numerical analysis results. The main conclusion to be drawn from this work is that multifunctional composite materials can indeed be used for nano-satellite structures and in the same light, can be tailor-made to the speci c mission requirements of the satellite. The technology is in its infancy still and has vast room for improvement and technological development beyond this work and well into the future. Further improvements and additional functions can be added through the inclusion of various other materials.
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Pinto, Fulvio. "Smart multifunctional composite materials for improvement of structural and non-structural properties." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589651.
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The principal aim of this thesis is to analyse the effectiveness of multifunctional smart materials as intelligent structures to improve mechanical properties and activate additional non-structural features. In order to investigate these multiple aspects, a comprehensive literature review has been presented focusing on the state of the art in multifunctional and smart materials. From this analysis, five different systems based on different designing solutions and manufacturing techniques were developed and experimentally validated. Multiscaled composites are a typical example of multifunctional materials and are based on the addition of engineered nanoscaled reinforcement to traditional mesoscopic systems. To test the effectiveness of nanomodification, an experimental campaign has been carried out, aimed to the characterisation of a nanocomposite obtained embedding Graphene Nanoplatelets (GNPs) in the polymeric structure of Low Density Polyethylene films at difference concentrations. Nanoscaled fillers were subsequently used to manufacture a threephasic multi-scaled composite based on the inclusion of nanometric SiO2 particles in a traditional carbon fabric/epoxy system. Following a different approach, hybrid structures with embedded Non-Newtonian fluids have been manufactured and tested and the results showed that nonlinear viscosity can be exploited to dynamically enhance material properties during an impact event. The possibility to intervene both on structural and non-structural properties has been investigated with another hybrid system, based on the embodiment of Shape memory Alloys (SMA) wires within a traditional unidirectional CFRP. The study of the impact properties pointed out that the superelasticity effect and the hysteretic stress/strain behaviour of the embedded wires reduce the extent of the internal delamination for samples subjected to low velocity impacts. Moreover, by exploiting the SMAs thermoelectrical properties it is possible to use the embedded metallic network as a strain sensor by measuring the electrical resistance variation and as an embedded heat source to be used for rapid thermographic damage location and evaluation.
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Brocklehurst, Simon Mark. "Three-dimensional structural studies on domains of multifunctional proteins." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339734.
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Evrard, Quentin. "Multifunctional layered simple hydroxides : structural investigations, functionalization and properties." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE007/document.
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Le but de cette thèse est l’obtention de matériaux multiferroïques par l’insertion de molécules organiques dans une matrice magnétique d’hydroxide simple lamellaire. Durant cette thèse a été démontré la faisabilité de la fonctionnalisation d’hydroxides simples lamellaires de cuivre et de cobalt par des molécules possédant des fonctions d’accroche acide phosphonique. Le développement des techniques de pré-fonctionnalisation a permis de fonctionnaliser ces hydroxides simple lamellaire par une variété importantes de molécules (fluorènes, benzènes, thiophènes et complexes de métaux de transition) afin d’apporter une propriété additionnelle au magnétisme de l’hydroxyde. Les premières mesures ont permis de mettre en évidence un couplage entre temperature d’ordre magnétique et anomalie diélectrique. La complexité de la mesure des propriétés diélectriques avec ces échantillons (sur poudre pastillées à froid) ont mis en lumière la nécessité d’obtenir des tailles de cristallites plus importantes. Des efforts sur la taille des cristallites ont donc été effectués et ont permis d’obtenir des monocristaux d’hydroxy- dodecylsulfate de cuivreThe main goal of this thesis is to obtain multiferroic materials via the intercalation of organic molecules in a magnetic inorganic matrix made of layered simple hydroxide. The possibility to use phosphonic acid as grafting moiety for the functionalization of layered simple hydroxides has been demonstrated during this thesis. Pre-functionalization techniques has allowed the functionalization of layered simple hydroxides of copper and cobalt with a wide variety of molecules (fluorenes, benzenes, thiophenes or transition- metal complexes) to bring an additional property to the magnetic properties of the layered hydroxide. The first measurements revealed a coupling between magnetic ordering temperature and dielectric anomaly. The dielectric properties measurements proved to be difficult with the samples (on cold-pressed pellets) and shown the usefulness of developing new methods to improve the cristallite size. To that end, new syntheses procedures led to the obtention of mono crystals of copper-hydroxidodecylsulfonate allowing to get additional structural informations
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Šmídová, Eva. "Obytný soubor Brno - Červený kopec." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225813.
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The residential area in Brno - Červený kopec is multifunctional new part of the city of Brno. Urban development based on the Žlutý kopec and Veveří. Historically, the studied area is located at the brickyard Kohn, who is now a brownfield site. The idea was to create a readable and clearly definable urban structure in relation to the proposed road network. The core area is dense five-storey mixed-use residential buildings with commercial parterre, which makes maximum use of space and brings order to the scattered houses in the area.
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Račko, Valentín. "Intenzivní dům v Brně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-394026.
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This master thesis is exploring a possibility of densifying traditional block structure of a city by the design of a multifunctional building. It is located in Brno exactly in Brno centrum city part. The building site is defined by Veveří, Kounicova and Pekárenská streets. On the forth side there is existing block of flats on the Sokolská Street. The design itself is based on the form of a traditional enclosed block of flats, but masses are oriented differently. The basic principle is layering when first two floors are commercially oriented and therefore accessible by public. Living areas are separated by position above. The roof, connecting all of the buildings, is taking role of a traditional courtyard. In this case, it stays visually connected with surrounding street life and newly formed commercial parts. Masses of the complex are reflecting different city structures on each side. It encloses on the side of the Veveří Street which creates undisturbed street corridor. New structure opens more to Kounicova Street and reflects free city pattern of this part.
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Wang, Shuang [Verfasser]. "Amphiphilic carbohydrate-containing compounds for multifunctional nano/macro structures / Shuang Wang." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1230628304/34.
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Meng, Han. "Acoustic properties of novel multifunctional sandwich structures and porous absorbing materials." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC008/document.
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La mise en oeuvre de matériaux acoustiques est une méthode efficace et très utilisée pour réduire le bruit le long de sa propagation. Les propriétés acoustiques de nouvelles structures sandwich multifonctionnelles et de matériaux absorbants poreux sont étudiées dans la thèse. Les principales contributions de la thèse sont les suivantes: Les panneaux sandwich ont généralement d'excellentes propriétés mécaniques et un bon indice de perte en transmission sonore (STL), mais aucune capacité d'absorption acoustique. De nouvelles structures sandwich multifonctionnelles sont développées en intégrant des microperforations et des matériaux absorbants poreux aux panneaux sandwich ondulés et en nid d’abeilles conventionnels, structurellement efficaces pour obtenir de bons STL et de bonnes absorptions en basses fréquences. Le coefficient d'absorption acoustique (SAC) et la perte en transmission (STL) des panneaux sandwich ondulés sont évalués numériquement et expérimentalement en basse fréquence pour différentes configurations de perforations. Les modèles éléments finis (EF) sont construits en tenant compte des interactions vibro-acoustiques sur les structures et des dissipations d'énergie, visqueuse et thermique, à l'intérieur des perforations. La validité des calculs FE est vérifiée par des mesures expérimentales avec les échantillons testés obtenus par fabrication additive. Par rapport aux panneaux sandwich ondulés classiques sans perforation, les panneaux sandwich perforés (PCSPs) avec des perforations dans leur plaque avant présentent non seulement un SAC plus élevé aux basses fréquences, mais aussi un meilleur STL, qui en est la conséquence directe. L'élargissement des courbes des indices d’absorption et de transmission doit être attribué à la résonance acoustique induite par les micro-perforations. Il est également constaté que les PCSPs avec des perforations dans les plaques avant et les parois internes onduleés ont les fréquences de résonance les plus basses de tous les PCSPs. En outre, les performances acoustiques des panneaux sandwich en nid d'abeilles avec une plaque avant microperforée sont également examinées. Un modèle analytique est présenté avec l'hypothèse que les déplacements des deux plaques sont identiques aux fréquences inférieures à la fréquence de résonance des plaques. Le modèle analytique est ensuite validé par des modèles d'éléments finis et des résultats expérimentaux existants. Contrairement aux panneaux sandwich en nid d'abeilles classiques qui sont de piètres absorbeurs de bruit, les sandwichs en nid d'abeilles perforés (PHSPs) conduisent à un SAC élevé aux basses fréquences, ce qui entraîne en conséquence un incrément dans le STL basse fréquence. Les influences de la configuration du noyau sont étudiées en comparant les PHSPs avec différentes configurations de noyaux en nids d'abeilles. […]Implementation of acoustic materials is an effective and popular noise reduction method during propagation. Acoustic properties of novel multifunctional sandwich structures and porous absorbing materials are studied in the dissertation. The main contributions of the dissertation are given as, Sandwich panels generally have excellent mechanical properties and good sound transmission loss (STL), but no sound absorption ability. Novel multifunctional sandwich structures are developed by integrating micro perforations and porous absorbing materials to the conventional structurally-efficient corrugated and honeycomb sandwich panels to achieve good SAC and STL at low frequencies. Low frequency sound absorption and sound transmission loss (STL) of corrugated sandwich panels with different perforation configurations are evaluated both numerically and experimentally. Finite element (FE) models are constructed with considerations of acousticstructure interactions and viscous and thermal energy dissipations inside the perforations. The validity of FE calculations is checked against experimental measurements with the tested samples provided by additive manufacturing. Compared with the classical corrugated sandwich panels without perforation, the perforated corrugated sandwich panels (PCSPs) with perforations in its face plate not only exhibits a higher SAC at low frequencies but also a better STL as a consequence of the enlarged SAC. The enlargement of SAC and STL should be attributed to the acoustical resonance induced by the micro perforations. It is also found that the PCSPs with perforations in both the face plates and corrugated cores have the lowest resonance frequencies of all the PCSPs. Besides, the acoustic properties of honeycomb sandwich panels with microperforated faceplate are also explored. An analytical model is presented with the assumption that displacements of the two faceplates are identical at frequencies below the faceplate resonance frequency. The analytical model is subsequently verified by finite element models and existing experimental results. Unlike classical honeycomb sandwich panels which are poor sound absorbers, perforated honeycomb sandwiches (PHSPs) lead to high SAC at low frequencies, which in turn brings about increment in the low frequency STL. Influences of core configuration are investigated by comparing PHSPs with different honeycomb core configurations. In order to enlarge the SAC bandwidth of perforated sandwich panels, porous absorbing materials are added to the cores of novel perforated sandwich panels. FE models are set up to estimate the SAC and STL of perforated sandwich panels with porous materials. Results show that perforated sandwich panels with porous material can provide SAC with broader bandwidth and lower resonance frequency than that without porous materials. Whereas the peak values in the SAC and STL curves are reduced due to the weakened acoustical resonance by the porous materials. […]
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Maňásková, Kristýna. "Polyfunkční dům v Uherském Hradišti." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226660.
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The subject of diploma thesis is the construction of technical project documentation for building realization - Multifunctional building in the town of. The object has three floors with residential attic and basement garage. The land is in the city center Uherské Hradiště and This is a building in the vacant space between existing objects. Construction is rectangular in shape, roofed with a gable roof and is designed from traditional building materials.
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Benák, Dalibor. "Stavebně-technologický projekt polyfunkčního domu v Brně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226997.
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This master's thesis focuses on a preparation of a multifunctional building in Brno, on Vídeňská street. It is based on a project that has been realized in 2005. Construction-technological preparation of this project includes the design of securing of time, financial, and human resources, project of construction site layout, a design of construction machines setup, technological manual for construction of monolithic reinforced concrete structure, plan of controls and tests for quality, and a manual for obtaining permission for using public space and protection of historical tree.
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Šaár, Martin. "Polyfunkční dům v řadové zástavbě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265644.
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The diploma thesis deals with the design documentation of new Multifunctional house in terraced houses on the level of documentation for building permit. The living area is designed for housing eight people. Part with shops and with offices are designed for seventy three people. The building will be located in the Zlín Region, District of Uherské Hradiště, in the city of Uherský Brod. The Cadastral area is Uherský Brod - the town. The bulding has four aboveground floors and he hadn't cellar. The building is designed like a brick structure with column and girder. Vertical structures aboveground parts are made of bricks Porotherm and column and girder are from reinforced concrete C16/20 and shoring B500B. Platform of a multifunctional house in terraced houses is of rectangular shape with dimensions of 25,20 x 16,30 m. The main entrance to the building is located on the south side. Part with shops in first floor have four shops. In the second floor are four offices. Whole building are roofed helped three diferent roof construction. Above living part is gabled roof and above technical room and staircase is compact flat roof and the rest of building is vegetation roof with terrace.
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Deng, Yinhu. "Bio-inspired Multifunctional Coatings and Composite Interphases." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-212223.
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Graphene nanoplatelets have been introduced into the interphase between electrically insulating glass fibre and polymer matrix to functionalize the traditional composite. Owing to the distribution of network structure of GNPs, the interphase can transfer the signals about various internal change of material. Consequently, due to the novel bio-inspired overlapping structure, our GNPs-glass fibre shows a unique opportunity as a micro-scale multifunctional sensor.
The following conclusions can be drawn from present research:
• We prepared GNPs solution via a scalable and highly effective liquid-phase exfoliation method. This method produces high-quality, unoxidized graphene flakes from flake graphite. We control the thickness and size of GNPs by varying the centrifugation rate.
• A simple fibre oriented capillary flow which can suppress ‘coffee ring’ effect to deposit GNPs onto the curved glass fibre surface. The GNPs form continuous fish scales like overlapping structure.
• The electrical conductivity of our GNPs-glass fibre shows semiconductive property. The electrical resistance value scattering and the advancing contact angle value scattering indicate a uniform deposit structure. The uniform overlapping structure is a key factor for higher electrical conductivity compared with our previous work with CNTs.
• The contact angles of our GNPs-glass fibre with water indicate that the GNPs are almost unoxidized, so the inert GNPs coating decreases the interfacial shears strength.
• A micro scale GNPs-glass fibre sensor for gas sensing is achieved by deposit GNPs onto glass fibre surface. This sensor can be used to detect solvents vapours, such as water, ethanol and acetone. All these vapours work as electron acceptor when reacting with GNPs. The acetone shows the highest sensitivity (45000%) compared with water and ethanol.
• The doping-dedoping of GNPs-glass fibres during adsorption-desorption cycles of acetone result in the efficient “break-junction” (GNPs lost electron carrier concentration) mechanism, which provides the possibility to fabricate the electrochemical “switch” in a simple and unique way.
• The resistance of our GNPs-glass fibre shows exponential relationship with RH. This is attributed to two points. Firstly, the water vapours show similar exponential adsorption on carbon surface; secondly, the bandgap of GNPs increases with the increase of adsorbed water vapour concentration.
• Due to the weak van der Waals interaction when water molecules are adsorbed on GNPs surface, our GNPs-glass fibre shows extreme fast response and recovery time with RH. It is potential for our GNPs-glass fibre being used to monitor the breath frequency.
• Utilizing the negative temperature coefficient of GNPs, our GNPs-glass fibre can be used as temperature sensor with a sensing region of -150 to 30 °C.
• Through the observed abnormal resistance change at a temperature of about – 18 °C, we discovered a phase change of the trance confined water in graphene layers. Based on the resistance change, we can study the interaction of water and carbon nanoparticles.
• The bio-inspired novel overlapped multilayer structure of GNPs coating shows structural colours. Even more, our GNPs-glass fibre can be used to monitor the loading force in the interphase when it is embedded into epoxy resin.
• Our GNPs-glass fibre shows an excellent piezoresistive property, the single GNPs-glass fibre shows a larger gauge factor than the commercial strains sensor.
• The semiconductive interphase was formed when the GNPs-glass fibre was embedded in polymer matrix. This semiconductive interphase is very sensitive to the deformation of material, therefore, an in-situ strain sensor was manufactured to real-time monitor the microcracks in a composite instead of external sensors. The area of resistance ‘jump’ increase can be seen as the feature area for damage’s early warning.
• Monitoring the resistance variation of the single fibre composite was conducted under cyclic loading with progressively increasing the strain peaks in order to further investigate the response of in-situ sensor to the interphase damage process. The deviation of resistance/strain when the stress is larger than 2 % highlights the accumulation of damage, which gives insight into the mechanism of resistance change.
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Yang, Heejae Ko Frank K. "Fabrication and characterization of multifunctional nanofiber nanocomposite structures through co-electrospinning process /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1782.
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Danner, Ann-Kathrin Maria [Verfasser]. "Multifunctional Amphiphilic Polyethers: From Polyether Lipids to Tapered Structures / Ann-Kathrin Maria Danner." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/1196133859/34.
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