This study investigated the effect of chain extender epoxy based additive, Joncryl ADR 4368, on the rheological, thermal and mechanical properties of poly(lactic acid) with poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends in the blown films form. Compositions with 40% and 60% by weight PLA were selected for production of such blown films. These dispersed phase content was chosen because the literature does not present mechanical behavior studies of tubular film blends with high concentration of the dispersed phase. Rheological analysis in dynamic oscillatory regime showed the reaction of epoxy group with end chain in both polymers, and a higher reactivity of the chain extender with PLA. The films produced exhibited different morphologies according to the blend composition and chain extender content. Films containing 40% PLA presented the dispersed phase morphology in a fibrillar form; however in the presence of chain extender, the dispersed phase is presented as ellipsoids. This change in morphology resulted in a reduction in the mechanical properties of these films in tensile tests. Films containing 60% PLA had a coarse morphology with dispersed phase in the ribbons-like form. The addition of extender yielded a refinement of the dispersed phase morphology from ribbon to elongated fibril form, which is responsible for the mechanical properties improvement of these films. Despite the low adhesion between matrix and dispersed phase, the proper setting of the morphology of the blends as a function of additive content, allowed to produce films with mechanical properties quite different from each other. / Neste trabalho foi estudado o efeito do aditivo extensor de cadeia à base de epóxi, Joncryl ADR 4368, nas propriedades reológicas, térmicas e mecânicas de filmes tubulares de blendas de poli(ácido láctico) com poli(butileno adipato-co-tereftalato) (PLA/PBAT). Composições com 40% e 60% em peso de PLA foram selecionadas para produção destes filmes tubulares. Estes teores de fase dispersa foram escolhidos pelo fato da literatura não apresentar estudos de comportamento mecânico de filmes tubulares de blendas com alta concentração da fase dispersa. Análises reológicas em regime dinâmico oscilatório evidenciaram a reação do grupo epóxi com finais de cadeia de ambos os polímeros, e evidenciaram uma maior reatividade do extensor com o PLA. Os filmes produzidos apresentaram diferentes morfologias de acordo com a composição da blenda e o teor de extensor de cadeia adicionado. Filmes contendo 40% de PLA apresentaram uma morfologia da fase dispersa na forma fibrilar; já na presença do extensor, a fase dispersa se apresentou na forma de elipsóides. Esta mudança na morfologia acarretou em uma redução nas propriedades mecânicas destes filmes em ensaios de tração. Filmes contendo 60% de PLA apresentaram uma morfologia grosseira com a fase dispersa na forma de fitas. A adição do extensor proporcionou um refinamento na morfologia da fase dispersa com formação de fibrilas alongadas, responsável pelo ganho nas propriedades mecânicas destes filmes. Apesar da baixa adesão entre matriz e fase dispersa, o ajuste apropriado da morfologia das blendas, em função do teor de aditivo, possibilitou produzir filmes com propriedades mecânicas bastante diferenciadas entre si.

The aim of the study was to design, build and experimentally verify a programmable thermostat. The main control unit of the thermostat is an ATmega168 microcontroller which communicates via I2C bus with remote MAX6615 chips. They are used to measure temperature with a set of thermistors and control the flow of the hot water in the heating system. This work deals with issues of remote control through the I2C bus, servomotor steering, precision temperature measurement and describes the inner workings of the system. The next chapter includes a proposal for possible extension of the system. The last part contains the manual of the control menu structure and a brief description of the software.

No description available.

Polysiloxanes represent a unique class of synthetic polymers, employing a completely inorganic backbone structure comprised of repeating –(Si–O)n– 'siloxane' main chain linkages. This results in an assortment of diverse properties exclusive to the siloxane bond that clearly distinguish them from the –(C–C)n– backbone of purely organic polymers. Previous work has elucidated a methodology for fabricating flexible and elastic crosslinked poly(dimethyl siloxane) (PDMS) constructs with high Mc through a simultaneous crosslinking and chain-extension methodology. However, these constructs suffer the poor mechanical properties typical of lower molecular weight crosslinked siloxanes (e.g. modulus, tear strength, and strain at break). Filled PDMS networks represent another important class of elastomers in which fillers, namely silica and siloxane-based fillers, impart improved mechanical properties to otherwise weak PDMS networks. This work demonstrates that proper silicon-based reinforcing agent selection (e.g. siloxane-based MQ copolymer nanoparticles) and incorporation provides a synergistic enhancement to mechanical properties, whilst maintaining a low viscosity liquid composition, at high loading content, without the use of co-solvents or heating. Rheological analysis evaluates the viscosity while photorheology and photocalorimetry measurements evaluate rate and extent of curing of the various MQ-loaded formulations, demonstrating theoretical printability up to 40 wt% MQ copolymer nanoparticle incorporation. Dynamic mechanical analysis (DMA) and tensile testing evaluated thermomechanical and mechanical properties of the cured nanocomposites as a function of MQ loading content, demonstrating a 3-fold increase in ultimate stress at 50 wt% MQ copolymer nanoparticle incorporation. VP AM of the 40 wt% MQ-loaded, photo-active PDMS formulation demonstrates facile amenability of photo-active PDMS formulations with high MQ-loading content to 3D printing processes with promising results. PDMS polyureas represent an important class of elastomers with unique properties derived from the synergy between the nonpolar nature, unusual flexibility, and low glass transition temperature (Tg) afforded by the backbone siloxane linkages (-Si-O)n- of PDMS and the exceptional hydrogen bond ordering and strength evoked by the bidentate hydrogen bonding of urea. The work herein presents an improved melt polycondensation synthetic methodology, which strategically harnesses the spontaneous pyrolytic degradation of urea to afford a series of PDMS polyureas via reactions at high temperatures in the presence of telechelic amine-terminated oligomeric poly(dimethyl siloxane) (PDMS1.6k-NH2) and optional 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BATS) chain extender. This melt polycondensation approach uniquely circumvents the accustomed prerequisite of isocyanate monomer, solvent, and metal catalysts to afford isocyanate-free PDMS polyureas using bio-derived urea with the only reaction byproduct being ammonia, a fundamental raw ingredient for agricultural and industrial products. As professed above, reinforcement of polysiloxane materials is ascertained via the incorporation of reinforcing fillers or nanoparticles (typically fumed silica) or blocky or segmented development of polymer chains eliciting microphase separation, in order to cajole the elongation potential of polysiloxanes. Herein, a facile approach is detailed towards the synergistic fortification of PDMS-based materials through a collaborative effort between both primary methods of polysiloxane reinforcement. A novel one-pot methodology towards the facile, in situ incorporation of siloxane-based MQ copolymer nanoparticles into segmented PDMS polyureas to afford MQ-loaded thermoplastic and thermoplastic elastomer PDMS polyureas is detailed. The isocyanate-free melt polycondensation achieves visible melt dispersibility of MQ copolymer nanoparticles (good optical clarity) and affords segmented PDMS polyureas while in the presence of MQ nanoparticles, up to 40 wt% MQ, avoiding post-polymerization solvent based mixing, the only other reported alternative. Incorporation of MQ copolymer nanoparticles into segmented PDMS polyureas provides significant enhancements to modulus and ultimate stress properties: results resemble traditional filler effects and are contrary to previous studies and works discussed in Chapter 2 implementing MQ copolymer nanoparticles into chemically-crosslinked PDMS networks. In situ MQ-loaded, isocyanate-free, segmented PDMS polyureas remain compression moldable, affording transparent, free-standing films. / Master of Science / Polysiloxanes, also referred to as 'silicones' encompass a unique and important class of polymers harboring an inorganic backbone. Polysiloxanes, especially poly(dimethyl siloxane) (PDMS) the flagship polymer of the family, observe widespread utilization throughout industry and academia thanks to a plethora of desirable properties such as their incredible elongation potential, stability to irradiation, and facile chemical tunability. A major complication with the utilization of polysiloxanes for mechanical purposes is their poor resistance to defect propagation and material failure. As a result polysiloxane materials ubiquitously observe reinforcement in some fashion: reinforcement is achieved either through the physical or chemical incorporation of a reinforcing agent, such as fumed silica, or through the implementation of a chemical functionality that facilitates reinforcement via phase separation and strong associative properties, such as hydrogen bonding. This research tackles polysiloxane reinforcement via both of these strategies. Facile chemical modification permits the construction PDMS polymer chains that incorporate hydrogen bonding motifs, which phase separate to afford hydrogen bond-reinforced phases that instill vast improvements to elastic behavior, mechanical and elongation properties, and upper-use temperature. Novel nanocomposite formulation through the incorporation of MQ nanoparticles (which observe widespread usage in cosmetics) facilitate further routes toward improved mechanical and elongation properties. Furthermore, with growing interest in additive manufacturing strategies, which permit the construction of complex geometries via an additive approach (as opposed to conventional manufacturing processes, which require subtractive approaches and are limited in geometric complexity), great interest lies in the capability to additively manufacture polysiloxane-based materials. This work also illustrates the development of an MQ-reinforced polysiloxane system that is amenable to conventional vat photopolymerization additive manufacturing: chemical modification of PDMS polymer chains permits the installation of UV-activatable crosslinking motifs, allowing solid geometries to be constructed from a liquid precursor formulation.

Made available in DSpace on 2014-06-11T19:29:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-26Bitstream added on 2014-06-13T19:38:31Z : No. of bitstreams: 1 crespilho_am_me_botfmvz.pdf: 507525 bytes, checksum: a1c92f545e77b50838125fbea8dfddd6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A despeito das inúmeras variáveis que influenciam direta e indiretamente a fertilidade das fêmeas bovinas, a qualidade das amostras seminais exerce um papel importante na determinação das taxas de concepção dos programas de inseminação artificial. Os objetivos dessa pesquisa foram comparar a efetividade de dois diluidores de criopreservação de sêmen bovino no processamento de amostras seminais apresentando diferentes concentrações espermáticas em relação aos índices de congelabilidade determinados laboratorialmente (Experimento I) e as taxas de concepção proporcionadas por cada metodologia quando utilizada em programas de inseminação artificial em tempo fixo (IATF) em bovinos (Experimento II). No Experimento I foram utilizados 14 ejaculados de diferentes touros da raça Nelore. Cada ejaculado foi fracionado em oito alíquotas iguais, submetidas a criopreservação com os diluidores Tris-gema de ovo-frutose (meio TRIS) e MKA nas concentrações de 12, 25, 50 e 100 milhões de espermatozóides totais por mililitro de meio, formando oito grupos experimentais em função das variáveis diluidor e concentração. As amostras foram descongeladas a 46 ºC por 20 segundos, avaliando-se os padrões de motilidade através do método computadorizado (CASA), integridade de membrana plasmática (IMP), resistência ao teste de termorresistência rápido (TTR) e taxa de recuperação e IMP após seleção espermática pela técnica de swim-up. Para o Experimento II foram selecionados sete touros utilizados no Experimento I, obtendo-se um ejaculado de cada animal por eletroejaculação... / Although there are many variables which directly or indirectly influence female bovine fertility, the quality of sperm samples plays a important role in the determination of conception rates in artificial insemination programs. The aim of the present study was to compare the efficiency of two bovine semen extenders for sperm freezing with different spermatic concentrations in the freezability determined by lab tests (Experiment I), and conception rates after fixed time artificial insemination (FTAI; Experiment II). In Experiment I 14 ejaculates of different Nelore bulls were used. Each ejaculate was splitsampled in to eight equal parts and then submitted to cryopreservation with Tris-egg yolk fructose (TRIS) and MKA extenders, at concentrations of 12, 25, 50 and 100 millions spermatozoa per milliliter forming eight experimental groups. The samples were thawed at 46 ºC for 20 seconds, and the following parameters were evaluated: sperm motility and movement (by computer-assisted semen analysis - CASA), sperm membrane integrity (SMI), resistance to the fast thermoresistance test (TT), recovery rate and sperm membrane integrity after sperm selection through swim-up technique. Seven of 14 bulls used in Experiment I were selected for Experiment II, and semen was collected from each of the animals by electroejaculation. The seven ejaculates obtained were mixed (semen pool) and cryopreserved, thus forming eight experimental groups according to the freezing extenders and sperm concentrations/straws: TRIS 12, 25, 50 and 100, and MKA 12, 25, 50 and 100...(Complete abstract, click electronic address below)

This thesis describes the design of a four-stroke engine with two cylinders, using as a range extender. The first chapter briefly introduces the company Škoda Auto a.s., for which the range extender was designed. Also, there is a list of the available electric and hybrid vehicles manufactured by this company. The next chapter deals with the division of hybrid vehicles, as an intermediate step for the use of electric vehicles, the reason for their use and the definition of advantages and disadvantages of hybrid vehicles. Also, the range extender technology is described here. The third chapter contains a description of the conceptual design of the range extender and describes the design and balancing of the crankshaft in more detail. The last chapter describes the calculation of the crankshaft dynamics and the individual parts load. The resulting crankshaft safety is determined by comparing the calculated values with a series-produced 1.0 MPI evo engine, which is the base of the described range extender.

[ES] A la luz de la crisis medioambiental y del creciente interés en el uso del H2 para avanzar hacia la Economía del Hidrógeno, esta tesis tiene como objetivo analizar y optimizar nuevas arquitecturas de sistemas propulsivos de FCV para aplicaciones en turismos y vehículos pesados en términos de rendimiento, durabilidad e impacto medioambiental. Para ello, se ha desarrollado una plataforma de modelado de FCV multifísica y flexible que integra un modelo de pila de combustible validado junto con los componentes del BoP, los componentes mecánicos y eléctricos del vehículo y el sistema propulsivo, un modelo de degradación de FC semi-empírico informado por tendencias físicas diseñado para ser utilizado en condiciones de conducción y un optimizador de EMS en tiempo real que ofrece el mejor rendimiento dado un diseño de sistema propulsivo y un ciclo de conducción, de tal forma que todas las arquitecturas propuestas para una aplicación determinada sean comparables en términos justos. La discusión de los resultados puede dividirse en tres partes diferentes. La primera está orientada a la optimización del rendimiento del FCS. Los resultados de esta parte ayudaron a identificar la estrategia de gestión del aire que, dado un conjunto de restricciones impuestas en los componentes del BoP, maximizaba la potencia neta del FCS (eficiencia) para cada valor de densidad de corriente. El balance energético resultante, que comprende la potencia producida por la pila de combustible, las perdidas electroquímicas y el consumo de los componentes del BoP, fue analizado y utilizado para determinar y diseñar la estrategia de control de los actuadores del BoP para condiciones de conducción. La segunda parte se centra en la evaluación y optimización, cuando es posible, de la arquitectura FCREx para aplicaciones de turismos y la configuración multi-FCS para aplicaciones de vehículos de transporte pesado. Desde el punto de vista del rendimiento, la arquitectura FCREx ofrecía un consumo mínimo de H2 con una elevada potencia de la pila de combustible y una gran capacidad de la batería, pero este diseño podría ser prohibitivo en términos de costes. Podía ofrecer hasta un 16.8-25% menos de consumo de H2 y un 6.8% menos de consumo de energía. La limitación en la dinámica de esta arquitectura aumento la durabilidad de la FC en un 110% con una penalización en el consumo de H2 del 4.7%. La arquitectura multi-FCS para aplicaciones pesadas podría funcionar con una dinámica aún menor, con un aumento de la durabilidad de la pila del 471% con una penalización en el consumo de H2 del 3.8%, ya que el perfil de conducción de los vehículos pesados suele ser menos dinámico. El control y el dimensionamiento diferencial solo podrían aportar beneficios en términos de impacto ambiental o de coste, pero no de rendimiento. La última parte considera los resultados obtenidos en términos de rendimiento y durabilidad para analizar el impacto medioambiental de cada arquitectura. La estrategia de producción de H2 afecta significativamente a las emisiones del ciclo de vida en ambas aplicaciones sobre cualquier otra elección de diseño. El diseño óptimo para la arquitectura FCREx que minimiza las emisiones tiene una alta potencia de la pila de combustible y una capacidad moderada de la batería. En el caso de la aplicación para vehículos pesados, se identificó la dinámica de control óptima para cada diseño y estrategia de producción de H2, y se determinó que la estrategia de diseño de dimensionado diferencial solo proporcionaba beneficios si se consideraba una tecnología de pila de combustible diferente para las distintas pilas integradas en el sistema propulsivo. / [CA] A la llum de la crisi mediambiental i del creixent interés en l'ús de l'H2 per a avançar cap a l'Economia de l'Hidrogen, aquesta tesi té com a objectiu analitzar i optimitzar noves arquitectures de sistemes propulsius de FCV per a aplicacions en turismes i vehicles pesants en termes de rendiment, durabilitat i impacte mediambiental. Per a això, s'ha desenvolupat una plataforma de modelatge de FCV multifísica i flexible que integra un model de pila de combustible validat juntament amb els components del BoP, els components mecànics i elèctrics del vehicle i el sistema propulsiu, un model de degradació de pila de combustible semi-empíric informat per tendències físiques dissenyat per a ser utilitzat en condicions de conducció i un optimitzador d'EMS en temps real que ofereix el millor rendiment donat un disseny de sistema propulsiu i un cicle de conducció, de tal forma que totes les arquitectures proposades per a una aplicació determinada siguen comparables en termes justos. La discussió dels resultats pot dividir-se en tres parts diferents. La primera està orientada a l'optimització del rendiment del FCS. Els resultats d'aquesta part van ajudar a identificar l'estratègia de gestió de l'aire que, donat un conjunt de restriccions imposades en els components del BoP, maximitzava la potència neta del FCS (eficiència) per a cada valor de densitat de corrent. El balanç energètic resultant, que comprén la potència produïda per la pila de combustible, les pèrdues electroquímiques i el consum dels components del BoP, va ser analitzat i utilitzat per a determinar i dissenyar l'estratègia de control dels actuadors del BoP per a condicions de conducció. La segona part se centra en l'avaluació i optimització, quan ¿es possible, de l'arquitectura FCREx per a aplicacions de turismes i la configuració multi-FCS per a aplicacions de vehicles de transport pesat. Des del punt de vista del rendiment, l'arquitectura FCREx oferia un consum mínim d'H2 amb una elevada potència de la pila de combustible i una gran capacitat de la bateria, però aquest disseny podría ser prohibitiu en termes de costos. Podia oferir fins a un 16.8-25% menys de consum d'H2 i un 6.8% menys de consum d'energia. La limitació en la dinàmica d'aquesta arquitectura va augmentar la durabilitat de la pila en un 110% amb una penalització en el consum d'H2 del 4.7%. L'arquitectura multi-FCS per a aplicacions pesades podria funcionar amb una dinàmica encara menor, amb un augment de la durabilitat de la pila del 471% i una penalització en el consum d'H2 del 3.8%, ja que el perfil de conducció dels vehicles pesants sol ser menys dinàmic. El control i el dimensionament diferencial només podrien aportar beneficis en termes d'impacte ambiental o de cost, però no de rendiment. L'última part considera els resultats obtinguts en termes de rendiment i durabilitat per a analitzar l'impacte mediambiental de cada arquitectura. L'estratègia de producció d'H2 afecta significativament a les emissions del cicle de vida en totes dues aplicacions sobre qualsevol altra elecció de disseny. El disseny òptim per a l'arquitectura FCREx que minimitza les emissions té una alta potència de la pila de combustible i una capacitat moderada de la bateria. En el cas de l'aplicació per a vehicles pesants, es va identificar la dinàmica de control `optima per a cada disseny i estratègia de producció d'H2, i es va determinar que l'estratègia de disseny de dimensionament diferencial només proporcionava beneficis si es considerava una tecnologia de pila de combustible diferent per a les diferents piles integrades en el sistema propulsiu. / [EN] In light of the environmental crisis and the growing interest in the use of H2 to advance toward the Hydrogen Economy, this thesis aims at analyzing and optimizing novel FCV powerplant architectures for passenger car and heavy-duty vehicle applications in terms of performance, durability, and environmental impact. For that purpose, a multi-physics flexible FCV modeling platform was developed integrating a validated FC stack model together with the BoP components, the mechanical and electrical components of the vehicle and powertrain, a semi-empirical physics-informed FC degradation model designed to be used in driving conditions and a real-time EMS optimizer that offers the best performance given a powerplant design and driving cycle so that all the proposed architectures for a given application are comparable. The discussion of the results can be divided into 3 different parts. The first one is oriented towards the FCS performance optimization. The results in this part helped to identify the air management strategy that, given a set of constraints imposed in the BoP components, maximized the FCS net power output (efficiency) for each value of current density. The resulting energy balance comprising the FC stack power produced, the electrochemical losses, and the consumption of the BoP components was analyzed and used to determine and design the control strategy of the BoP actuators for driving cycle conditions. The second part is focused on the evaluation and optimization, when possible, of the FCREx architecture for passenger car applications and the multi-FCS configuration for heavy-duty vehicle applications. Performance-wise the FCREx architecture offered minimum H2 consumption with high FC stack power and high battery capacity, but this design could be prohibitive in terms of costs. It could offer up to 16.8-25% lower H2 consumption and 6.8% lower energy consumption. Limiting the dynamics of this architecture increased the FC durability by 110% with a penalty in H2 consumption of 4.7%. The multi-FCS architecture for heavy-duty applications could operate with even lower dynamics, with an increase in the FC durability of 471% with a penalty in H2 consumption of 3.8%, since the driving profile of heavy-duty vehicles is usually more steady. Differential control and sizing could only provide benefits in terms of environmental impact or cost, not performance. The last part considers the results obtained in terms of performance and durability to analyze the environmental impact of each architecture. The H2 production pathway affected significantly the life cycle emissions of both applications over any other design choice. The optimum design for FCREx architecture that minimized emissions had high FC stack power and moderate battery capacity. In the case of heavy-duty application, the optimum control dynamics for each design and H2 production pathway were identified, and the differential sizing design strategy was determined to only provide benefits if different FC stack technology was considered for the various stacks in the powerplant. / López Juárez, M. (2022). Analysis of Hydrogen Fuel Cell Powerplant Architectures for Future Transport Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/189212

Brennstoffzellen stellen aufgrund ihrer Vielseitigkeit, ihres Wirkungsgrades und ihrer systembedingten Vorteile eine ausgezeichnete Lösung zur Erzeugung von elektrischer Energie bei Bedarf dar. Zahlreiche Projekte haben die prinzipielle Einsatzbereitschaft dieser Technologie für stationäre, maritime und mobile Anwendungen gezeigt. Der Markthochlauf steht jedoch derzeit vor einigen Hürden. Besonderes Augenmerk wird darauf gelegt, wie kleine und mittlere Unternehmen (KMU) diese überwinden können. Diese Hindernisse werden im Kontext der allgemeinen Marktsituation im Allgemeinen sowie in der Brennstoffzellenindustrie grundlegend analysiert. Möglichkeiten zur Kostensenkung bei steigenden Produktionsmengen und zur Sicherstellung der erforderlichen Produktqualität werden diskutiert. Die zu produzierenden Stückzahlen sind je nach Marktsegment sehr unterschiedlich. Daher ist es unerlässlich, dass die Produktionskapazitäten mit der tatsächlichen Nachfrage nach Brennstoffzellensystemen und -produkten wachsen. Ein universelles Brennstoffzellensystem, das nur einfache Anpassungen für verschiedene Anwendungen erfordert, kann hier eine Lösung sein. / Fuel cells represent an excellent solution for generating electrical power on demand because of their versatility, efficiency and system-related advantages. Numerous projects have shown the readiness of this technology for stationary, maritime and mobile applications. However the market ramp-up presently faces certain hurdles. Particular attention is paid to how small and medium sized enterprises (SMEs) can overcome them. These obstacles are put in context by an analysis of the general market Situation within the fuel cell industry. Opportunities for the reduction of costs as production quantities ramp up whilst assuring the necessary product quality are discussed. The quantities involved are vary between individual market segments. Therefore it is imperative that production capacities grow in line with the actual demand for fuel cell systems and products. A universal fuel ce/1 system design which only needs simple adaptations for different applications can be a solution here.