906 resultados para Screw-threads.


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Este artigo trata dos conflitos entre a estrutura econômica e política neoliberal do capitalismo e a proposta de cidadania e de defesa de direitos do Serviço Social crítico no cotidiano profissional das instituições. Analisa as relações de exploração articuladas às relações de poder e de sobrevivência e às relações entre profissionais e sujeitos demandantes de serviços, para identificar desafios do exercício profissional na reflexão e na aprendizagem da tomada de consciência e construção de estratégias de contra-hegemonia na complexidade do cotidiano. _______________________________________________________________________________ ABSTRACT

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Dissertação de Mestrado, Engenharia Civil, Especialização em Estruturas, Instituto Superior de Engenharia, Universidade do Algarve, 2016

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Doutoramento em Engenharia dos Biossistemas - Instituto Superior de Agronomia - UL

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"This article analyses performance consumptions among young people. The theme is explored along two main axes. The first concerns the social heterogeneity in this field, considered on two levels: the different purposes for those investments – cognitive/mental and physical performance; and the different social contexts – university and work – where performance practices and dispositions may be fostered. The second axis explores the roles of pharmacological and natural consumptions, and their interrelationship, in the dissemination of these practices. The empirical data for this analysis were drawn from an ongoing research project on performance consumptions among young people (aged 18−29 years) in Portugal, including both university students and young workers without university education. The results correspond to the stage of extensive research, for which a questionnaire was organised at a national level, using non-proportional quota sampling. On the one hand, they show that (a) there is a hierarchy of acceptance of consumptions according to their purposes, with cognitive/mental performance showing higher acceptance and (b) both pharmaceuticals and natural products are consumed for every type of performance investment. On the other, the comparison between students and workers introduces a certain heterogeneity in this general backdrop, both in terms of the purposes for their consumptions and their opting for natural or pharmacological resources. These threads of heterogeneity will prompt a discussion of the dynamics of pharmaceuticalisation within the field of performance, in particular how therapeutic cultures may be changing in terms of the way individuals relate to medications, expanding their uses in social life."

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Direito, Pós-Graduação Stricto Sensu em Direito, 2016.

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Dissertação de dout. em Literatura (Literatura e Cultura Clássicas), Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2005

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This employment has the function the utilization of mango seeds Tommy Atkins, like starch source to obtain biopolymers and fibers source and nanowhiskers cellulose also, that will be use like reinforcing fillers in micro and nanobiocomposites polymeric. The fibers in natura removed from tegument mango seed were characterized, as weel as the treated fibers and nanowhiskers of cellulose extracted from them. The starch extracted from seed s almond showed a good performance (32%) and a high purity. The chemicals analyzes, of crystallinity and morphological of the fibers in natura, treated fibers and nanowhiskers of cellulose confirmed the efficacy of the chemical treatement performed to remove amorphous constituents (hemicellulose and lignina). The thermoplastic starch (TPS) obtained from two sources, corn starch and starchy material mango, was produced in a twin screw extruder with compositon mass of 62,5% of starch, 9,4% of water and 28,1% of glycerol. The starch material mango was the main objective of this work for the production of biodegradable materials, and the starch corn was utilized during the production stage to evaluate the processability of the starch and use as parameter for comparison, according of being a conventional source for obtaining conventional comercial starch. The incorporation of fibers (6% in mass) and nanowhiskers cellulose (1% in mass) in matrix of TPS to obtain composite and nanocomposite, respectively, it was performed in single screw extruder. The biocomposites and bionanocomposites polymeric were obtained and the TPS from starchy material mango presented better results of thermal and mechanicals properties when compared to TPS corn starch. Concludes that the sediment generated of the agroindustrial processing mango used presents potencial to producing of biodegradables materials

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The development of new materials to fill the demand of technological advances is a challenge for many researchers around the world. Strategies such as making blends and composites are promising alternatives to produce materials with different properties from those found in conventional polymers. The objective of this study is to evaluate the effect of adding the copolymer poly(ethylene methyl acrylate) (EMA) and cotton linter fibers (LB) on the properties of recycled poly(ethylene terephthalate) (PETrec) by the development of PETrec/EMA blend and PETrec/EMA/LB blend composite. In order to improve the properties of these materials were added as compatibilizers: Ethylene - methyl acrylate - glycidyl methacrylate terpolymer (EMA-GMA) and maleic anhydride grafted polyethylene (PE-g-MA). The samples were produced using a single screw extruder and then injection molded. The obtained materials were characterized by thermogravimetry (TG), melt flow index (MFI) mensurements, torque rheometry, pycnometry to determinate the density, tensile testing and scanning electron microscopy (SEM). The rheological results showed that the addition of the EMA copolymer increased the viscosity of the blend and LB reduces the viscosity of the blend composite. SEM analysis of the binary blend showed poor interfacial adhesion between the PETrec matrix and the EMA dispersed phase, as well as the blend composite of PETrec/EMA/LB also observed low adhesion with the LB fiber. The tensile tests showed that the increase of EMA percentage decreased the tensile strength and the Young s modulus, also lower EMA percentage samples had increased the elongation at break. The blend composite showed an increase in the tensile strength and in the Young`s modulus, and a decrease in the elongation at break. The blend formulations with lower EMA percentages showed better mechanical properties that agree with the particle size analysis which showed that these formulations presented a smaller diameter of the dispersed phase. The blend composite mechanical tests showed that this material is stronger and stiffer than the blend PETrec/EMA, whose properties have been reduced due to the presence of EMA rubbery phase. The use of EMA-GMA was effective in reducing the particle size of the EMA dispersed phase in the PETrec/EMA blend and PE-g-MA showed evidences of reaction with LB and physical mixture with the EMA

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Nacomposites of polymers and lamellar clayminerals, has generated high scientific and technological interest, for having mechanical properties and gas barriers differentiated of polymers and conventional composites. In this work, it was developed nanocomposites by single screw extruder and injection, utilizing commercial raw material, with the goal to investigate the quality of new developed materials. It was evaluated the influence of the content and the kind of clay in the structure and in the nanocomposites properties. It was used regular and elastomeric poly (methyl methacrylate) (Acrigel LEP 100 and Acrigel ECP800) and six montmorillonites (Cloisite 10A, 11B, 15A, 20A, 25A e 30B) at the concentration of 1% e 3% in weight. The nanocomposites were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), colorimetric, optical transparency, flexural and tensile tests, Rockwell hardness and esclerometry. It was founded that is possible to obtain intercalated and exfoliated nanocomposites PMMA/MMT, and the top results was obtained in the materials with 1%in clay weight organophilizated with 2M2HT (Cloisite 15A and 20A) presented intercalate and hybrid morphology (exfoliated and flocullated). The ones that was produced with organophilizated clay with 2MHTL8 (Cloisite 30B) had excellent visual quality, but the majority presented hybrid morphology. In the materials processed with organophilizated clay with MT2ETOH (Cloisite 30B), there were color change and loss of transparency. It occurs improvement in a few mechanical properties, mainly in the materials produced with PMMA elastomeric (Acrigel ECP800), being more significant, the increase in the resistance to stripping in those nanocomposites

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The natural raw materials acquired special importance beside the mineral raw materials with the need for using alternative sources to oil, because they can be used to produce biopolymers. Gelatin, produced from the denaturation of collagen, and starch, an abundant polysaccharide in various plants, are examples of biopolymers which have several technological applications, especially in films. The objective of this work is to produce polymeric bioblends with gelatin and corn starch using two types of gelatin: commercial bovine gelatin and gelatin produced from mechanically separated flesh of tilapia (Oreochromis niloticus). For the extraction of tilapia gelatin 3 distinct pretreatments, followed by extraction in distilled water under heating were performed. The properties of gelatin extracted were similar to bovine gelatin, and the differences can be explained by the difference in extraction processes and sources. Blends of commercial gelatin and starch were produced in an internal mixer from a Haake torque rheometer, to study the behavior of the gelatin mixture with starch, thus, the same compositions were processed by twin screw extrusion, to define the mixing parameters. Subsequently, the extrusion of blends of tilapia gelatin and corn starch was carried out in the same twin screw extruder. The physico-chemical, rheological and morphological properties of the blends with thermoplastic starch and gelatin were studied. It was found that various properties vary linearly with increasing concentration of the components. The blends produced are immiscible, and among the two gelatins, tilapia gelatin showed a better interfacial adhesion with the corn starch. Regarding the morphology, gelatins formed the dispersed phase in all compositions studied, even in compositions rich in starch. Can be concluded that the procedure for tilapia gelatin extraction is feasible and advantageous, and the increasing in its scale to a reactor of 30 liters is possible, with a satisfactory yield. The bioblends of bovine gelatin/corn starch and tilapia gelatin/corn starch were successfully produced, and the processing conditions were appropriate

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In the multi-core CPU world, transactional memory (TM)has emerged as an alternative to lock-based programming for thread synchronization. Recent research proposes the use of TM in GPU architectures, where a high number of computing threads, organized in SIMT fashion, requires an effective synchronization method. In contrast to CPUs, GPUs offer two memory spaces: global memory and local memory. The local memory space serves as a shared scratch-pad for a subset of the computing threads, and it is used by programmers to speed-up their applications thanks to its low latency. Prior work from the authors proposed a lightweight hardware TM (HTM) support based in the local memory, modifying the SIMT execution model and adding a conflict detection mechanism. An efficient implementation of these features is key in order to provide an effective synchronization mechanism at the local memory level. After a quick description of the main features of our HTM design for GPU local memory, in this work we gather together a number of proposals designed with the aim of improving those mechanisms with high impact on performance. Firstly, the SIMT execution model is modified to increase the parallelism of the application when transactions must be serialized in order to make forward progress. Secondly, the conflict detection mechanism is optimized depending on application characteristics, such us the read/write sets, the probability of conflict between transactions and the existence of read-only transactions. As these features can be present in hardware simultaneously, it is a task of the compiler and runtime to determine which ones are more important for a given application. This work includes a discussion on the analysis to be done in order to choose the best configuration solution.

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Hardware vendors make an important effort creating low-power CPUs that keep battery duration and durability above acceptable levels. In order to achieve this goal and provide good performance-energy for a wide variety of applications, ARM designed the big.LITTLE architecture. This heterogeneous multi-core architecture features two different types of cores: big cores oriented to performance and little cores, slower and aimed to save energy consumption. As all the cores have access to the same memory, multi-threaded applications must resort to some mutual exclusion mechanism to coordinate the access to shared data by the concurrent threads. Transactional Memory (TM) represents an optimistic approach for shared-memory synchronization. To take full advantage of the features offered by software TM, but also benefit from the characteristics of the heterogeneous big.LITTLE architectures, our focus is to propose TM solutions that take into account the power/performance requirements of the application and what it is offered by the architecture. In order to understand the current state-of-the-art and obtain useful information for future power-aware software TM solutions, we have performed an analysis of a popular TM library running on top of an ARM big.LITTLE processor. Experiments show, in general, better scalability for the LITTLE cores for most of the applications except for one, which requires the computing performance that the big cores offer.

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In questo lavoro si analizza il rendimento isoentropico di diversi espansori adottati all’interno di sistemi micro-ORC (Organic Rankine Cycle). Si parte da una descrizione generale dei sistemi ORC, mettendone in evidenza le principali caratteristiche, il layout tipico, le differenze rispetto ad un ciclo Rankine tradizionale, e gli ambiti di utilizzo. Si procede ad una trattazione teorica del rendimento isoentropico del compressore e dell’espansore, specificando le ipotesi adottate nei calcoli e mettendo in luce la relazione tra rendimento isoentropico e politropico nell’uno e nell’altro apparato. Si passa poi alla descrizione delle quattro principali tipologie di espansori presenti in letteratura: scroll, screw, vane e piston, e si prosegue con l'analisi nel dettaglio della letteratura relativa alla valutazione dell’efficienza di questi quando utilizzati all’interno di un sistema micro-ORC. Infine, dopo aver descritto il sistema ORC del laboratorio di via Terracini del DIN, illustrandone layout, componenti principali, potenza scambiata all’interno dei componenti e modalità di calcolo adottata per la valutazione del rendimento isoentropico dell’espansore e del sistema complessivo, si confrontano i dati di efficienza di questo con quelli reperiti in letteratura. Il confronto del rendimento, dell'espansore e complessivo, del sistema del DIN, 33.8% e 1,818% rispettivamente, con quelli degli altri sistemi, è risultato di difficilmente valutazione a causa delle condizioni di forte off-design del sistema stesso. Dalla ricerca è inoltre emerso che i fluidi più utilizzati nella sperimentazione, e dunque capaci di migliori prestazioni, sono R245fa, R134a e R123. Per quel che riguarda infine gli espansori, nel range di potenza di 1-10 kW, lo scroll risulta essere il migliore.

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Concurrent software executes multiple threads or processes to achieve high performance. However, concurrency results in a huge number of different system behaviors that are difficult to test and verify. The aim of this dissertation is to develop new methods and tools for modeling and analyzing concurrent software systems at design and code levels. This dissertation consists of several related results. First, a formal model of Mondex, an electronic purse system, is built using Petri nets from user requirements, which is formally verified using model checking. Second, Petri nets models are automatically mined from the event traces generated from scientific workflows. Third, partial order models are automatically extracted from some instrumented concurrent program execution, and potential atomicity violation bugs are automatically verified based on the partial order models using model checking. Our formal specification and verification of Mondex have contributed to the world wide effort in developing a verified software repository. Our method to mine Petri net models automatically from provenance offers a new approach to build scientific workflows. Our dynamic prediction tool, named McPatom, can predict several known bugs in real world systems including one that evades several other existing tools. McPatom is efficient and scalable as it takes advantage of the nature of atomicity violations and considers only a pair of threads and accesses to a single shared variable at one time. However, predictive tools need to consider the tradeoffs between precision and coverage. Based on McPatom, this dissertation presents two methods for improving the coverage and precision of atomicity violation predictions: 1) a post-prediction analysis method to increase coverage while ensuring precision; 2) a follow-up replaying method to further increase coverage. Both methods are implemented in a completely automatic tool.

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Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder which may result from repetitive brain injury. A variety of tau-immunoreactive pathologies are present, including neurofibrillary tangles (NFT), neuropil threads (NT), dot-like grains (DLG), astrocytic tangles (AT), and occasional neuritic plaques (NP). In tauopathies, cellular inclusions in the cortex are clustered within specific laminae, the clusters being regularly distributed parallel to the pia mater. To determine whether a similar spatial pattern is present in CTE, clustering of the tau-immunoreactive pathology was studied in the cortex, hippocampus, and dentate gyrus in 11 cases of CTE and 7 cases of Alzheimer’s disease neuropathologic change (ADNC) without CTE. In CTE: (1) all aspects of tau-immunoreactive pathology were clustered and the clusters were frequently regularly distributed parallel to the tissue boundary, (2) clustering was similar in two CTE cases with minimal co-pathology compared with cases with associated ADNC or TDP-43 proteinopathy, (3) in a proportion of cortical gyri, estimated cluster size was similar to that of cell columns of the cortico-cortical pathways, and (4) clusters of the tau-immunoreactive pathology were infrequently spatially correlated with blood vessels. The NFT and NP in ADNC without CTE were less frequently randomly or uniformly distributed and more frequently in defined clusters than in CTE. Hence, the spatial pattern of the tau-immunoreactive pathology observed in CTE is typical of the tauopathies but with some distinct differences compared to ADNC alone. The spread of pathogenic tau along anatomical pathways could be a factor in the pathogenesis of the disease.