392 resultados para inefficiency
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In this work are discussed the main types of rivets, their characteristics and applicability within the Aeronautical Industry branch. Here are highlighted the solid rivets, showing off its layout, forms and limits of installation, that are required by aviation regulators. The riveting is a popular and simple procedure of fixing and joining two or more parts, and like any other manufacturing process is subject to process deviations that in some situations are beyond the limits of tolerance. One of these deviations is when the hole diameter exceeds the one proposed in project and which is limited by the rule of edge distance. The overall objective here is to study a possible solution to this problem: the installation of a rivet that has his diameter previously increased by compression. Observe the hole filling after riveting, detect the presence of cracks, discover the yield curve of the fasteners and their the crushing limits for failure prediction are tools used to verify this proposal. They demonstrate, at the end of study, the inefficiency of this procedure, with results that go against the safe fixing of parts in a structure
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Endodontic sealer residues on dentinal surface have negative effects on adhesion of adhesives system and/or can cause discoloration of the dental crown. Objective: To evaluate the efficacy of 95% ethanol in removal of residues of epoxy-based (AH Plus), methacrylate-based (Epiphany SE) or calcium-based (Sealapex) sealers on dentinal surface. Material and methods: Thirty-two bovine incisor dental crown fragments (0.5 mm x 0.5 mm) were treated with 17% EDTA and 2.5% NaOCl. The specimens were divided into three experimental groups (n = 10): G1 (AH Plus), G2 (Epiphany SE) and G3 (Sealapex). In each group was applied a coating of one endodontic sealer type and were left undisturbed for 5 minutes. After this period, the specimens were cleaned with 95% ethanol. The control group was composed by two specimens that did not receive any sealer or cleaning treatment. The sealer residues persistence after cleaning with 95% ethanol was evaluated by scanning electron microscopy (x500) and a score system was applied. Data obtained were analyzed by Kruskal-Wallis and Dunn tests (α = 5%). Results: Moderate amount of endodontic sealer residues were observed in all groups, regardless of the endodontic sealer compositions. G1, G2 and G3 presented similar amount of sealer residues on dentinal surface after cleaning with 95% ethanol (p > 0.05). Conclusion: 95% ethanol was inefficiency to remove completely AH Plus, Epiphany SE and Sealapex residues of sealer-contaminated dentin.
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Introduction: Endodontic sealer residues on dentinal surface have negative effects on adhesion of adhesives system and/or can cause discoloration of the dental crown. Objective: To evaluate the efficacy of 95% ethanol in removal of residues of epoxy-based (AH Plus), methacrylate-based (Epiphany SE) or calcium-based (Sealapex) sealers on dentinal surface. Material and methods: Thirty-two bovine incisor dental crown fragments (0.5 mm x 0.5 mm) were treated with 17% EDTA and 2.5% NaOCl. The specimens were divided into three experimental groups (n = 10): G1 (AH Plus), G2 (Epiphany SE) and G3 (Sealapex). In each group was applied a coating of one endodontic sealer type and were left undisturbed for 5 minutes. After this period, the specimens were cleaned with 95% ethanol. The control group was composed by two specimens that did not receive any sealer or cleaning treatment. The sealer residues persistence after cleaning with 95% ethanol was evaluated by scanning electron microscopy (x500) and a score system was applied. Data obtained were analyzed by Kruskal-Wallis and Dunn tests (α = 5%). Results: Moderate amount of endodontic sealer residues were observed in all groups, regardless of the endodontic sealer compositions. G1, G2 and G3 presented similar amount of sealer residues on dentinal surface after cleaning with 95% ethanol (p > 0.05). Conclusion: 95% ethanol was inefficiency to remove completely AH Plus, Epiphany SE and Sealapex residues of sealercontaminated dentin.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Geografia - IGCE
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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This paper addresses the effects of bank competition on the risk-taking behaviors of banks in 10 Latin American countries between 2003 and 2008. We conduct our empirical approach in two steps. First, we estimate the Boone indicator, which is a measure of competition. We then regress this measure and other explanatory variables on the banking "stability inefficiency" derived simultaneously from the estimation of a stability stochastic frontier. Unlike previous findings, this paper concludes that competition affects risk-taking behavior in a non-linear way as both high and low competition levels enhance financial stability, while we find the opposite effect for average competition. In addition, bank size and capitalization are essential factors in explaining this relationship. On the one hand, the larger a bank is, the more it benefits from competition. On the other hand, a greater capital ratio is advantageous for banks that operate in collusive markets, while capitalization only enhances the stability of larger banks under high and average competition. These results are of extreme importance when considering bank regulations, especially in light of the recent turmoil in the global financial markets. (C) 2012 Elsevier B.V. All rights reserved.
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This paper focuses on the relationship between metropolitan and regional health planning based on the processes of regionalization and the Pact for Health in the Baixada Santista Metropolitan Area, Sao Paulo State, Brazil. The method used was a case study in two stages, namely during initial implementation of the Pact for Health (2007) and the Regional Administration Committees (CGR) and in 2010. Municipal and regional health systems managers and the director of the Metropolitan Agency were interviewed, and records were analyzed from ten years of meetings of the Regional Inter-Administration Committee and the Regional Development Council. Four issues emerged: financing and infrastructure; health services utilization; inefficiency of the Regional Health Administration's instruments and decision-making levels; and the relationship between different levels in the Administration. Metropolitan health management remained as an underlying issue, appearing only incidentally or tangentially to regional management. Despite some limitations, the CGR has been legitimized as a space for regional health management.
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The Space Telescope Imaging Spectrograph (STIS) has been on orbit for approximately 16 years as one of the 2nd generation instruments on the Hubble Space Telescope (HST). Its operations were interrupted by an electronics failure in 2004, but STIS was successfully repaired in May 2009 during Service Mission 4 (SM4) allowing it to resume science observations. The Instrument team continues to monitor its performance and work towards improving the quality of its products. Here we present updated information on the status of the FUV and NUV MAMA and the CCD detectors onboard STIS and describe recent changes to the STIS calibration pipeline. We also discuss the status of efforts to apply a pixel-based correction for charge transfer inefficiency (CTI) effects to STIS CCD data. These techniques show promise for ameliorating the effects of ongoing radiation damage on the quality of STIS CCD data.
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The ever-increasing spread of automation in industry puts the electrical engineer in a central role as a promoter of technological development in a sector such as the use of electricity, which is the basis of all the machinery and productive processes. Moreover the spread of drives for motor control and static converters with structures ever more complex, places the electrical engineer to face new challenges whose solution has as critical elements in the implementation of digital control techniques with the requirements of inexpensiveness and efficiency of the final product. The successfully application of solutions using non-conventional static converters awake an increasing interest in science and industry due to the promising opportunities. However, in the same time, new problems emerge whose solution is still under study and debate in the scientific community During the Ph.D. course several themes have been developed that, while obtaining the recent and growing interest of scientific community, have much space for the development of research activity and for industrial applications. The first area of research is related to the control of three phase induction motors with high dynamic performance and the sensorless control in the high speed range. The management of the operation of induction machine without position or speed sensors awakes interest in the industrial world due to the increased reliability and robustness of this solution combined with a lower cost of production and purchase of this technology compared to the others available in the market. During this dissertation control techniques will be proposed which are able to exploit the total dc link voltage and at the same time capable to exploit the maximum torque capability in whole speed range with good dynamic performance. The proposed solution preserves the simplicity of tuning of the regulators. Furthermore, in order to validate the effectiveness of presented solution, it is assessed in terms of performance and complexity and compared to two other algorithm presented in literature. The feasibility of the proposed algorithm is also tested on induction motor drive fed by a matrix converter. Another important research area is connected to the development of technology for vehicular applications. In this field the dynamic performances and the low power consumption is one of most important goals for an effective algorithm. Towards this direction, a control scheme for induction motor that integrates within a coherent solution some of the features that are commonly required to an electric vehicle drive is presented. The main features of the proposed control scheme are the capability to exploit the maximum torque in the whole speed range, a weak dependence on the motor parameters, a good robustness against the variations of the dc-link voltage and, whenever possible, the maximum efficiency. The second part of this dissertation is dedicated to the multi-phase systems. This technology, in fact, is characterized by a number of issues worthy of investigation that make it competitive with other technologies already on the market. Multiphase systems, allow to redistribute power at a higher number of phases, thus making possible the construction of electronic converters which otherwise would be very difficult to achieve due to the limits of present power electronics. Multiphase drives have an intrinsic reliability given by the possibility that a fault of a phase, caused by the possible failure of a component of the converter, can be solved without inefficiency of the machine or application of a pulsating torque. The control of the magnetic field spatial harmonics in the air-gap with order higher than one allows to reduce torque noise and to obtain high torque density motor and multi-motor applications. In one of the next chapters a control scheme able to increase the motor torque by adding a third harmonic component to the air-gap magnetic field will be presented. Above the base speed the control system reduces the motor flux in such a way to ensure the maximum torque capability. The presented analysis considers the drive constrains and shows how these limits modify the motor performance. The multi-motor applications are described by a well-defined number of multiphase machines, having series connected stator windings, with an opportune permutation of the phases these machines can be independently controlled with a single multi-phase inverter. In this dissertation this solution will be presented and an electric drive consisting of two five-phase PM tubular actuators fed by a single five-phase inverter will be presented. Finally the modulation strategies for a multi-phase inverter will be illustrated. The problem of the space vector modulation of multiphase inverters with an odd number of phases is solved in different way. An algorithmic approach and a look-up table solution will be proposed. The inverter output voltage capability will be investigated, showing that the proposed modulation strategy is able to fully exploit the dc input voltage either in sinusoidal or non-sinusoidal operating conditions. All this aspects are considered in the next chapters. In particular, Chapter 1 summarizes the mathematical model of induction motor. The Chapter 2 is a brief state of art on three-phase inverter. Chapter 3 proposes a stator flux vector control for a three- phase induction machine and compares this solution with two other algorithms presented in literature. Furthermore, in the same chapter, a complete electric drive based on matrix converter is presented. In Chapter 4 a control strategy suitable for electric vehicles is illustrated. Chapter 5 describes the mathematical model of multi-phase induction machines whereas chapter 6 analyzes the multi-phase inverter and its modulation strategies. Chapter 7 discusses the minimization of the power losses in IGBT multi-phase inverters with carrier-based pulse width modulation. In Chapter 8 an extended stator flux vector control for a seven-phase induction motor is presented. Chapter 9 concerns the high torque density applications and in Chapter 10 different fault tolerant control strategies are analyzed. Finally, the last chapter presents a positioning multi-motor drive consisting of two PM tubular five-phase actuators fed by a single five-phase inverter.
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The aim of my project is to find operational strategies for increasing the commercial exploitation of fish in Apulia region and to acquire a thorough knowledge of several important aspects of this system order to propose concrete, suitable and appropriate development tools. The plan is to analyze the impact that the socio-economic context has on blue fish systems of fishing and marketing in the various maritime regions. The sector of fishery is typified by a settled downward trend due to both communitarian policies driving towards a reduction of the fishery effort and to reduction of fishing resources. In the same time in Italy a increasing of costs (expecially fuel) and a reduction of market prices, because of the increasing of imports, are observed. Although a big part of Italian fishing fleet is to be referred to Apulia region, this dynamics are worsen, here, also because of market inefficiency and lack of integration and cooperation among fishermen. In this first part of my work I have investigated two areas that are relevant for regional fishery. On a first step I have evaluated fish amount for each kind of dealer working in each one of the two areas than, according to Porter's value chain analysis theory. Than i have applied the approach of value system to evaluate the value chains of the firm's supplier, the firm of fishery itself, and the firms distribution channels. Distribution of value has been resulted different but very unfavorable to fisherman in both investigated areas. The second step of my study has been the evaluation of the social capital value in both areas, defining the networks of fishery consistence and number of their mutual relationship. Results lay stress on a relation to an higher social capital value and a distribution of value system more profitable for fishermen.
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Dopo gli indubbi sviluppi politici e legali tendenti all’uniformazione è inevitabile non sostenere che anche il mercato della gestione delle infrastrutture e del trasporto aereo a terra costituisce un fattore determinante del trasporto aereo con una più stretta necessità di uniformazione del quadro regolamentare. La gestione aeroportuale e i servizi connessi è collocata all’interno del diritto aereo. Perché si configuri il “trasporto aereo” (nozione dinamica base che caratterizza il diritto del trasporto aereo) si ha la necessità di un accordo tra due paesi – un permesso di volo designato – una finestra di orario di decollo e atterraggio e la regolamentazione delle relative attività connesse, affinché si svolgano in situazione di safety, quale conditio sine qua non di tutte le attività di aviazione. Tuttavia, la migliore dottrina sente il bisogno di una trattazione separata della materia diritto aereo in senso stretto e quella della disciplina aeroportuale, benché i due ambiti sono tra di loro contigui. Questo è legittimato da esigenze contrapposte fra gli operatori dei due settori. In ultima considerazione possiamo sostenere che gli sviluppi legislativi, sia nel diritto aeronautico e in quello marittimo, portano all’abbraccio della impostazione di un diritto dei trasporti inclusivo di ogni forma dell’attuazione del fenomeno trasporto, scollegandosi al solo fenomeno dell’esercizio nautico quale elemento caratterizzante della disciplina. Quale futuro legislativo si prospetta per la gestione del bene aeroporto? Quale sarà la sua dimensione legale su questioni importanti sulle quali esiste una normazione europea come l’allocazione delle bande orarie, tasse aeroportuali e assistenza a terra oppure su quelle che hanno un carattere prevalentemente nazionale? E infine, quale sarebbe la strada da seguire per regolare il nuovo mercato aeroportuale che è passato dalla idea della competizione per il mercato esplorando anche la competizione nel mercato, con aeroporti che si comportano come operatori in concorrenza tra loro?
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Modern food systems are characterized by a high energy intensity as well as by the production of large amounts of waste, residuals and food losses. This inefficiency presents major consequences, in terms of GHG emissions, waste disposal, and natural resource depletion. The research hypothesis is that residual biomass material could contribute to the energetic needs of food systems, if recovered as an integrated renewable energy source (RES), leading to a sensitive reduction of the impacts of food systems, primarily in terms of fossil fuel consumption and GHG emissions. In order to assess these effects, a comparative life cycle assessment (LCA) has been conducted to compare two different food systems: a fossil fuel-based system and an integrated system with the use of residual as RES for self-consumption. The food product under analysis has been the peach nectar, from cultivation to end-of-life. The aim of this LCA is twofold. On one hand, it allows an evaluation of the energy inefficiencies related to agro-food waste. On the other hand, it illustrates how the integration of bioenergy into food systems could effectively contribute to reduce this inefficiency. Data about inputs and waste generated has been collected mainly through literature review and databases. Energy balance, GHG emissions (Global Warming Potential) and waste generation have been analyzed in order to identify the relative requirements and contribution of the different segments. An evaluation of the energy “loss” through the different categories of waste allowed to provide details about the consequences associated with its management and/or disposal. Results should provide an insight of the impacts associated with inefficiencies within food systems. The comparison provides a measure of the potential reuse of wasted biomass and the amount of energy recoverable, that could represent a first step for the formulation of specific policies on the integration of bioenergies for self-consumption.