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Henne, Ingo [Verfasser]. "Schädigungsverhalten von Aluminiumgusslegierungen bei TMF und TMF/HCF-Beanspruchung / Ingo Henne." Aachen : Shaker, 2006. http://d-nb.info/1166513785/34.
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Hill, Michael Anthony Ph D. Massachusetts Institute of Technology. "Computational methods for higher real K-theory with applications to tmf." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34545.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2006.Includes bibliographical references (p. 67-69).
We begin by present a new Hopf algebra which can be used to compute the tmf homology of a space or spectrum at the prime 3. Generalizing work of Mahowald and Davis, we use this Hopf algebra to compute the tmf homology of the classifying space of the symmetric group on three elements. We also discuss the E3 Tate spectrum of tmf at the prime 3. We then build on work of Hopkins and his collaborators, first computing the Adams-Novikov zero line of the homotopy of the spectrum eo4 at 5 and then generalizing the Hopf algebra for tmf to a family of Hopf algebras, one for each spectrum eop_l at p. Using these, and using a K(p - 1)-local version, we further generalize the Davis-Mahowald result, computing the eop_1 homology of the cofiber of the transfer map [...]. We conclude by computing the initial computations needed to understand the homotopy groups of the Hopkins-Miller real K-theory spectra for heights large than p- 1 at p. The basic computations are supplemented with conjectures as to the collapse of the spectral sequences used herein to compute the homotopy.
by Michael Anthony Hill.
Ph.D.
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Yamane, Junko. "Functional involvement of TMF/ARA160 in Rab6-dependent retrograde membrane traffic." Kyoto University, 2007. http://hdl.handle.net/2433/135781.
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Miller, Maria R. "SYNTHESIS AND APPLICATION OF NINE NOVEL ANALOGS OFTRYPSIN MODULATING OOSTATIC FACTOR (TMOF)IN THE MOSQUITO, Aedes aegypti." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000724-102408.
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The search continues for an environmentally safe, low cost, fast acting insecticide formosquitoes. Mosquitoes have been the cause of large-scale epidemics, such as yellowfever, dengue fever, and dengue hemorrhagic fever over the centuries. Even now, due tothe increase in the Aedes aegypti population, the threat still exists. In this research, six of nine compounds were synthesized as potential analogs of the decapeptide TMOF(trypsin modulating oostatic factor), which has already been identified as a growthinhibitor in mosquitoes. The nine compounds were derived from three different startingmaterials and six were completed in eight or fewer steps. These compounds were tested for larvacidal activity by feeding studies using Aedes aegypti. The compound 7-(3,4-dimethoxyphenyl)-4-heptenoic acid resulted in the lowest LC50, 0.62mM.
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Nguyen, Tuan Phuong [Verfasser]. "Methodenentwicklung zur Lebensdauerberechnung hinsichtlich thermo-mechanischer Ermüdung (TMF) an motorischen Bauteilen / Tuan Phuong Nguyen." Aachen : Shaker, 2017. http://d-nb.info/1138177385/34.
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Hopkinson, John R. (John Robert). "Universal polynomials in lambda rings and the K-theory of the infinite loop space tmf." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34544.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2006.Includes bibliographical references (p. 100-101).
The algebraic structure of the K-theory of a topological space is described by the more general notion of a lambda ring. We show how computations in a lambda ring are facilitated by the use of Adams operations, which are ring homomorphisms, and apply this principle to understand the algebraic structure. In a torsion free ring the Adams operations completely determine the lambda ring. This principle can be used to determine the K-theory of an infinite loop space functorially in terms of the K-theory of the corresponding spectrum. In particular we obtain a description of the K-theory of the infinite loop space tmf in terms of Katz's ring of divided congruences of modular forms. At primes greater than 3 we can also relate this to a Hecke algebra.
by John R. Hopkinson.
Ph.D.
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Loureiro-Homs, Jordi. "Modelling of TMF Crack Growth in Polycrystalline Gas Turbine Alloys : Accounting for Crack Closure Effects." Licentiate thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170275.
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The main objective of the work presented in this Licentiate of Engineering thesis is to investigate and model the fatigue crack propagation behaviour of the nickel-based superalloy Inconel 792, with special attention to the industrial lifing of high-temperature components. In-phase (IP) crack propagation tests have been performed at different temperatures and loading regimes, including extended hold times. The observations from these tests have been the basis for establishing several hypotheses to describe the crack growth behaviour, which progressively have been verified experimentally and numerically. Most prominently, it has been observed that crack closure has a substantial impact on crack growth and can explain, to a large degree, the crack growth behaviour for this material under the conditions studied. This phenomenon has been observed experimentally and modelled numerically to extend further the precision of the methodology.Huvudsyftet med arbetet som presenteras i denna licentiat avhandling är att undersöka och modellera utmattnings sprickväxtbeteendet hos den nickelbaserade superlegeringen Inconel 792, med särskild uppmärksamhet riktad mot liuslängsdmodellering av högtemperaturkomponenter i en industriell kontext. I-fas (IP) sprickväxtprov har utförts vid olika temperaturer och belastningsregimer, inklusive hålltider. Observationerna från dessa tester har legat till grund för hypoteser för att förklara spricktillväxtbeteende, vilka successivt har verifierats experimentellt och numeriskt. Mest framträdande har det observerats att sprickslutning har en väsentlig inverkan på sprickväxten, och kan i stor utsträckning förklara sprickväxten för detta material under studerade förhållanden. Detta fenomen har observerats experimentellt och modellerats numeriskt för att förbättra metodens precision.
Ytterligare forskningsfinansiär: Siemens Energy through "Turbines for Future Energy Systems" (Turbiner forframtidens energisystem), Grant No.44100-1
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Hormozi, Sheikhtabaghi Mohammad. "Experimental and numerical simulations of Type 316 stainless steel failure under LCF/TMF loading conditions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/18344.
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Materials need to be designed under certain conditions to withstand high thermal gradients to operate at high temperature environments. Many advanced gas cooled reactor (AGR) power plant components with operating temperatures in the range of 500-650 °C undergo creep-fatigue loading conditions. These components may be subject to isothermal low cycle fatigue (LCF) and thermo mechanical fatigue (TMF) damages due to the cyclic operation of power plant caused by the start-up and shutdown processes and due to the fluctuation of energy demand in daily operation. Hence, the influence of these cyclic loads induced mechanically and thermally, on the different structural components need to be carefully monitored and analysed in order to prevent failure and ensure safe operating conditions of critical units. The material Type 316 SS with cast number S7646, widely used in this type of components, is investigated in this project. The aim of this research is to conduct experimental tests to obtain quality stress-strain data for the material under investigation under cyclic plasticity in isothermal and an-isothermal tests using the available testing machine systems in the University of Imperial College London. The data obtained from experimental results are then utilised to develop advanced novel finite element damage models in a creep/fatigue loading environment in order to predict the cyclic behaviour under LCF conditions. Finally, the results of cyclic data derived from isothermal tests were used to predict the thermo mechanical fatigue behaviour for this alloy. The LCF-TMF testing unit, Instron 8801 with a temperature uniformity of less than ±10°C within the gauge section of the specimens were employed to conduct the experimental tests. Fully-reversed, strain-controlled isothermal tests were conducted at 500°C and 650°C for the strain ranges of ∆ɛ=±0.4%, ±0.8%, ±1.0% and ±01.2%. Strain-controlled in-phase (IP) thermo-mechanical fatigue tests were conducted on the same material and the temperature was cycled between 500°C and 650°C. Additionally, the creep-fatigue interactions were investigated with the introduction of symmetrical hold time at maximum strains in tension and compression under both LCF-TMF tests. From the investigation and the analysis of the experimental stress-strain data, three phases are observed when the cyclic stress responses are plotted; cyclic hardening, stabilisation and damage evolution. In the final stage of the behaviour of the material, a nonlinear decrease of the peak stress level was observed which was initiated by the presence of micro-crack and the failure occurred as the crack propagated. The evolution of inelastic strain energy density, ∆w, against the number of cycles, N, was used to determine the number of cycles at which the material stabilised, N_sta , the damage initiated, N_i and the failure occurred,N_f. The introduction of the hold time in both tension and compression strains in the LCF and TMF tests, produced an increase in the plastic strain range which subsequently increased the inelastic strain energy density and slightly reduced the peak flow stress when compared with the continues cyclic tests. The stress relaxation was observed when the hold time was introduced. The amount of stress relaxation was dependent on the test temperature and the imposed strain amplitude and the same trend was found when different strain ranges were examined. The cyclic behaviour of the Type 316 steel was further studied by analysing and performing microstructural investigations using the scanning electron microscope (SEM). The metallographic and the fractographic studies revealed that in all LCF-TMF tests the cracks mostly initiated in transgranular mode and propagated in either transgranular (under continuous cyclic loading) or in a mixed mode (under symmetric dwell period). The comparison of the metallographic and the fractographic studies of the LCF and TMF tests under both conditions (i.e. with and without dwell period) highlighted that the proportion of intergranular cracking increases with decrease in frequency, i.e. from 0.01Hz to 0.001Hz. Furthermore, the transgranular fatigue process dominates at high frequencies whereas the intergranular time dependent mechanism governs at low frequencies, low imposed mechanical strain amplitude and they both act together at intermediate frequencies and imposed mechanical strain amplitude. A constitutive model based on isotropic and nonlinear kinematic hardening rules was used to replicate numerically the cyclic structural behaviour of the material. A user-defined subroutine was developed and implemented in the finite element software, ABAQUS to predict the cyclic hardening, the stress relaxation during hold time and finally to demonstrate the damage evolution once the damage initiated. The final stage of the material behaviour (i.e. failure) was simulated numerically for both LCF and TMF tests conducted with and without hold time where for the tests with continuous cyclic loading (without hold time) a hysteresis energy-based phenomenological model was implemented in a USDFLD subroutine. Further, this model in combination with the creep damage model based on the time-fraction law were employed simultaneously to replicate the experimental results in which the hold time was introduced. In the end, the FE results were compared with the experimental results and the minor deviations observed in e.g. the first and stabilised hysteresis loops under TMF conditions or in the FE hysteresis damages, could be minimised by conducting further isothermal tests to define additional material properties at intermediate temperatures and performing tests at various strain ranges respectively.
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Frost, Laura Stephanie. "Characterisation of the Mitotic Golgi Phosphoproteins, TATA Modulatory Factor(TMF) and Zinc Finger Protein-Like 1 (ZFPL1)." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503762.
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Karjalainen, Marcus, and David Klarholm. "Termomekanisk utmattning av Sanicro 25 : Materialmodellering med finita elementmetoden." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-109409.
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The report aims to describe the austenitic stainless steel Sanicro 25 from a thermomechanical point of view. The thermal and mechanical properties of the material make it suitable for use in coal – and thermal power plants. By the use of Sanicro 25 it would be possible to bring the efficiency of these plants up while bringing the carbon emissions down.A material model is created from material testing and validated through simulation in the finite element software Abaqus. The model that has been derived describes the material behavior during loading and stress relaxation for the first cycle in a thermomechanical fatigue test well. The unloading part of the cycle however cannot be described correctly by the use of this model.Rostfritt
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Collin, Niklas. "Thermo-mechanical fatigue of castiron for engine applications." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156880.
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In an engine component the repeated start-stop cycles cause temporal and local inhomogeneous temperatures, which in turn lead to a type of low-frequency loading, plastic deformation and eventually failure due to thermo-mechanical fatigue. Simultaneously, high-frequency mechanical loading arises from the cyclic combustion pressure and from road induced vibrations. These types of loadings that mainly are in the elastic region are usually denoted high cycle fatigue (HCF). In order to improve efficiency, power density and to reduce emissions, future truck engines will be subjected to higher temperatures and higher combustion pressures which will affect the service life of the different engine components. As a consequence, there is a need to determine the limitations of the used alloys under these service conditions as exactly as possible. In this master thesis work the fatigue properties of one grey iron (EN-GJL 250) and one compacted graphite iron (EN-GJV 400) has been investigated under realistic loading conditions. The results show that a change from the grey iron to the compacted graphite iron will result in a significant increase of the fatigue life. The investigation also reveal that the life will increase significantly if the maximum temperature can be decreased tens of degrees. Further, the results indicate that addition of a relatively small HCF load may give a large decrease of the fatigue life.Motorkomponenter utsätts för upprepade start och stopp, vilka skapar tillfälliga och lokala temperaturvariationer. Dessa resulterar i lågfrekventa lastväxlingar, plastiska deformationer och eventuella brott i form av termodynamisk utmattning (TMF). Det sker dessutom en högfrekvent mekanisk last, genererad av förbränningen och från vägvibrationer. Dessa laster är mestadels elastiska och benämns högcykelutmattning (HCF). För att kunna förbättra verkningsgrad och minska emissioner kommer framtida lastbilsmotorer att utsättas för högre förbränningstryck och högre temperaturer, vilket kommer påverka motorernas livslängd. För detta krävs det att materialens begränsningar utreds under ett verklighetstroget förhållande. I detta exjobb kommer utmattningsegenskaperna för ett gråjärn (EN-GJL 250) och ett kompaktgrafikjärn (EN-GJV 400) utredas under realistiska lastförhållanden. Resultatet påvisar att ett byte från gråjärn till kompaktgrafitjärn ger en signifikant ökad livslängd. Det framkommer också att livslängden kan ökas genom att sänka den maximala temperaturen ett tiotal grader. Analysen påvisar även att en relativt liten HCF last kan ge kraftigt förkortad livslängd.
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Larsson, Karl. "Influence of nitrocarburization on the thermomechanical fatigue properties of ductile iron for exhaust components : Analysis and comparisons of TMF-properties." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-72033.
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New stricter environmental legislation requires lower emissions and fuel consumption of automotive engines. Therefore the fuel efficiency must be increased but this leads to higher loads in the engine. As for the exhaust system it is affected by higher thermomechanical loads. Until today the turbo manifold has been nitrocarburized in order to increase the wear resistance in slip joints with other exhaust components. The problem is that there is no knowledge of how the nitrocarburizing affects the thermomechanical properties of the material. The purpose of this thesis work is to examine the difference in thermomechanical properties with and without nitrocarburizing on the three different ductile irons High Silicon, SiMo51 and SiMo1000 intended for exhaust components. Thermo-mechanical fatigue (TMF) experiments were performed on test rods to evaluate difference in number of cycles to failure. In each cycle the test-rod was affected by a combination of mechanical loads and thermal loads resembling those found on exhaust components. Light optical microscopy, scanning electron microscopy and x-ray radiography were used to examine microcracks and damage mechanisms of the materials. It was found that the nitrocarburizing did not affect the number of cycles to failure in any large extent. Further, it was also found that SiMo1000 on average has the longest lifetime followed by SiMo51 and High Silicon. Although, the difference is small for many loadings and taking a 95% confidence band into account the curves overlap for many loading cases.
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Johansson, Johnny. "Weld Analysis in Combustion Chambers Subjected to Thermo-Mechanical Fatigue Load Conditions." Thesis, Linköpings universitet, Hållfasthetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69482.
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At cyclic operation of gas turbines, components are subjected to thermo-mechanical fatigue (TMF) due to the high temperature gradients that arises. In this thesis life assessment of welds in combustion chambers are at focus. Siemens Industrial Turbomachinery AB uses a method they call the HQ-method to estimate the TMF life of components, but how well this estimation work with welds have not been investigated before and is therefore unclear. Because of this unclearness, an additional reduction factor is used take this into account. The goal of this thesis is to conduct a study of welds in the combustion chambers to get an overview of welds that are present, and to identify eventual problems with those. Furthermore, an analysis of a selected weld is performed and the results are evaluated by using the HQ-method. For this analysis, a TIG weld on a test specimen of Hastelloy X is selected as both the weld method and the material are commonly used in combustion chambers. The specimen is chosen due to the possibility to verify the results using a test rig designed for TMF-tests. The results show that the HQ-method, with the assumptions made today, yields a life of welds considered very low compared with the base metal. Also the location of the most severely loaded point is questionable. Further investigations also show that residual stresses in the weld relax quickly and the creep rate of the weld does not make any particular difference to expected life. To verify the results and clarify some questions it is therefore suggested that the commenced investigation continues with real tests on the weld. As the results show that the creep rate is unimportant to the fatigue life, the parameter should be ruled out from the investigation and the objective should instead be to find the accurate yield strength of the weld, and study if failure occurs in or outside the weld.Vid cyklisk drift av gasturbiner utsätts komponenterna för termomekanisk utmattning (TMF) på grund av de höga temperaturgradienter som uppkommer. I detta arbete är livslängdsbedömningen av svetsar i brännkammare i fokus. Siemens Industrial Turbomachinery AB använder en metod som de kallar för HQ-metoden för att bedöma livslängden av komponenter utsatta för TMF men hur väl denna bedömning stämmer på svetsar är oklart. På grund av denna oklarhet används en extra reduceringsfaktor för att ta hänsyn till detta. Målet med detta arbete är att göra en undersökning av svetsar i brännkammare för att få en överblick av vilka svetsar som finns samt att identifiera eventuella problem med dessa. Vidare ska en analys på en utvald svets utföras och resultaten ska utvärderas med HQ-metoden. Till denna analys väljs en TIG-svets på en provstav av Hastelloy X då både svetsmetoden och materialet är vanligt förekommande i brännkammare. Provstaven valdes eftersom den ger en möjlighet att verifiera resultaten i en provrigg avsedd för TMF-prov. Resultaten visar att HQ-metoden, med de antaganden som görs idag, ger en livslängd på svetsar som är väldigt låg i förhållande till grundmaterialet. Också placeringen av den mest påkända punkten kan ifrågasättas. Vidare visar även undersökningen att restspänningar i svetsen relaxerar snabbt och att kryphastigheten i svetsen inte gör någon speciell skillnad på den förväntade livslängden. För att verifiera resultaten samt klargöra vissa frågetecken föreslås därför att den påbörjade undersökningen fortsätter med riktiga tester på svetsar. Eftersom resultaten visar att kryphastigheten endast är av ringa betydelse ska den parametern uteslutas ur undersökningen och målet ska istället vara att finna den korrekta sträckgränsen i svetsen samt studera om brott uppkommer i eller utanför svetsen.
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Wiegand, Anne Katharina Gisela [Verfasser], Jürgen [Akademischer Betreuer] Schlegel, and Thomas [Akademischer Betreuer] Korn. "Molekulare Charakterisierung der neuroprotektiven Wirkung transmembraner Proteine der TM9-Superfamilie und der TMEFF-Proteine / Anne Katharina Gisela Wiegand. Gutachter: Thomas Korn ; Jürgen Schlegel. Betreuer: Jürgen Schlegel." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1034642065/34.
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Oliveira, Filho Abrahão Alves de. "Participação da via do óxido nítrico e do cálcio no vasorrelaxamento induzido pelo flavonoide 5,7,4 trimetoxiflavona (TMF) em artéria mesentérica superior de rato." Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/6747.
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The pharmacological effects of ethanol extract (EPC), chloroform phase (FPC) and 5,7,4'-trimethoxyflavone (TMF) from Praxelis clematidea on superior mesenteric artery rings of rats, were studied. Isometric tension experiments revealed that EPC and FPC (0.001 to 1000 μg/mL) promoted concentration-dependent relaxation in mesenteric rings with functional endothelium (EC50 = 27.2 ± 6.4 μg/mL, 41.9 ± 11.8 μg/mL, respectively, n = 7), and these effects were attenuated after removal of the vascular endothelium (EC50 = 141.9 ± 19.4 μg/mL,167.0 ± 30.6 μg/mL, respectively, n = 7), suggesting that both are vasorelaxants secondary metabolites. The TMF (10-12 to 10-3 M), composed mostly isolated FPC, promoted a relaxation in rings with intact endothelium (pD2 = 5.44 ± 0.12, n = 6), concentration dependent manner, with power similar to the effect of quercetin, a flavonoid abundant in the plant kingdom (pD2 = 5.71 ± 0.16, n = 6). After removal of functional endothelium the concentration-response curve for the TMF was shifted to the right, with a decrease in potency, but no change in maximal effect (pD2 = 4.50 ± 0.10, n = 6). The relaxation of the flavonoid was not modified by pre-incubation of indomethacin (10 μM). However, it was attenuated after pre-incubation of L-NAME (100 μM, pD2 = 4.52 ± 0.08, n = 5), PTIO (300 μM, pD2 = 4.62 ± 0.09, n = 5 ) and ODQ (10 μM, pD2 = 4.36 ± 0.11, n = 5) and was reversed in preparations with functional endothelium pre-incubated with L-arginine (1 mM) plus L-NAME (100 μM) (pD2 = 5.85 ± 0.14, n = 5). Demonstrating the non-involvement of COX metabolites and participation of the NOS/NO/CGs pathway in the relaxation produced by TMF. The presence of 20 mM KCl (pD2 = 4.62 ± 0.08, n = 5) and TEA (3 mM; pD2 = 4.28 ± 0.10, n = 5) attenuated the response produced by TMF only in rings with endothelium, demonstrating that this compound produces relaxation through activation of K+ channels to endothelium-dependent. In addition, the use of glibenclamide (10 μM) did not modify the effect of TMF on rings with functional endothelium, but the pre-incubation of 4-aminopyridine (1 mM; pD2 = 4.7 ± 0.08, n = 5) and TEA (1 mM; pD2 = 4.48 ± 0.04, n = 5) attenuated the potency of the flavonoid vasorrelaxant response, suggesting the involvement of the K+ channels to Kv and BKCa type. TMF relaxations in mesenteric rings pre-contracted with 60 mM KCl and inhibited the vasoconstriction induced by CaCl2 concentration dependent manner. The maximum effect of TMF was mitigated by pre-incubation of nifedipine (1 μM, Emáx = 56.0 ± 7.9%, n = 5), indicating that the flavonoid-induced vasodilation is related to the inhibition of the influx of Ca2+ via L-type Cav. In conclusion, these results suggest that the EPC, the FPC and TMF inducing effect vasorrelaxante in mesenteric rings, and that the response produced by the flavonoid involves NOS/NO/CGs pathway, with consequent activation of channels for K+, and inhibition of the influx Ca2+ channels via L-type Cav.
Os efeitos farmacológicos do extrato etanólico (EPC), fase clorofórmica (FPC) e 5,7,4 -trimetoxiflavona (TMF) provenientes de Praxelis clematidea, sobre anéis de artéria mesentérica superior de ratos, foram estudados. Experimentos de tensão isométrica revelaram que EPC e FPC (0,001 1000 μg/mL) promoveram relaxamento dependente de concentração em anéis mesentéricos, com endotélio funcional (CE50 = 27,2 ± 6,4 μg/mL; 41,9 ± 11,8 μg/mL, respectivamente, n=7), e estes efeitos foram atenuados após a remoção do endotélio vascular (CE50 = 141,9 ± 19,4 μg/mL, 167,0 ± 30,6 μg/mL, respectivamente, n=7), sugerindo que ambos possuem metabólitos secundários vasorrelaxantes. O TMF (10-12 a 10-3 M), composto majoritário isolado de FPC, promoveu um relaxamento em anéis com endotélio intacto (pD2= 5,44±0,12, n=6), de maneira dependente de concentração, com potência semelhante ao efeito da quercetina, o flavonóide mais abundante no reino vegetal (pD2= 5,71±0,16, n=6). Após a remoção do endotélio funcional a curva concentração-resposta para o TMF foi deslocada para a direita, com uma diminuição da potência, porém sem alteração no efeito máximo (pD2 = 4,50 ± 0,10, n=6). O relaxamento do flavonóide não foi modificado pela pré-incubação de indometacina (10 μM). Entretanto, foi atenuado após a pré-incubação de L-NAME (100 μM; pD2 = 4,52 ± 0,08, n=5), PTIO (300 μM; pD2 = 4,62±0,09, n=5) e ODQ (10 μM; pD2 = 4,36 ± 0,11, n=5), e foi revertido em preparações com endotélio funcional pré-incubadas com L-arginina (1mM) mais L-NAME (100 μM) (pD2 = 5,85 ± 0,14, n=5). Demonstrando o não envolvimento dos metabólitos da COX e a participação da via NOS/NO/CGs no relaxamento produzido por TMF. A presença de KCl 20 mM (pD2 = 4,62 ± 0,08, n = 5) e TEA (3 mM; pD2 = 4,28 ± 0,10, n=5), atenuou a resposta produzida por TMF, apenas em anéis com endotélio vascular, demonstrando que este composto produz relaxamento por meio ativação de canais para K+, dependente do endotélio. Além disso, a utilização da Glibenclamida (10 μM) não modificou o efeito do TMF em anéis com endotélio funcional, porém a pré-incubação de 4-aminopiridina (1 mM; pD2 = 4,7 ± 0,08, n = 5), e TEA (1 mM; pD2 = 4,48 ± 0,04, n=5) atenuaram a potência da resposta vasorrelaxante do flavonóide, sugerindo o envolvimento dos canais para K+ do tipo Kv e BKca. TMF promoveu relaxamento em anéis mesentéricos pré-contraídos com KCl 60 mM e inibiu a vasoconstrição induzida pelo CaCl2 de maneira dependente de concentração. O efeito máximo de TMF foi atenuado com a pré-incubação de nifedipino (1 μM; Emáx = 56,0 ± 7,9%, n=5), indicando que a vasodilatação induzida pelo flavonóide está relacionada com a inibição do influxo de Ca2+ via Cav tipo L. Em conclusão, estes resultados sugerem que o EPC, a FPC e o TMF induzem efeito vasorrelaxante em anéis mesentéricos, e que a resposta produzida pelo flavonóide envolve a via NOS/NO/CGs, com consequente ativação de canais para K+, e a inibição do influxo de Ca2+ via canais para Cav tipo-L.
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Van, de Weg Martine Janet. "Leaf traits and foliar CO2 exchange in a Peruvian tropical montane cloud forest." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5300.
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Tropical montane cloud forests (TMCF) are one of the most fascinating, but least understood ecosystems in the world, and the interest in the carbon (C) cycle of TMCFs with regard to carbon sequestration and storage practices has increased rapidly in recent years. One feature that prevails in all TMCFs is a decrease in aboveground net primary productivity (ANPP) and standing biomass and leaf area index (LAI) with increasing altitude, together with the stunted growth form of the trees. This thesis focuses on the input part of the TMCF C-cycle, and investigates the controlling factors on photosynthesis on a leaf, canopy, and ecosystem level in the Kosñipata valley in south east Peru, on the eastern slope of the Andes (13º11’28’’S / 71º35’24’’W). Leaf traits are known to relate to foliar C-exchange, and compared with other altitudinal transect studies of TMCFs, the studied sites had similar altitudinal trends for foliar nitrogen (N) content (though not for phosphorus) and leaf mass per area (LMA), with N content decreasing and LMA increasing with altitude. N concentrations were relatively high and LMA values relatively low, but this observed relationship was consistent with those found in global leaf trait surveys. Examining plant stoichiometry (i.e. N:P ratios), the data suggests that unlike the general hypothesis, the Kosñipata forests are not N limited, except for the study site at 2990 m a.s.l. At the 2990 m a.s.l. site, which is the focal study site of the thesis, photosynthetic parameters Vcmax (the carboxylation efficiency of the Rubisco protein) and Jmax (the electron transport efficiency) proved to be similar to those found in lowland tropical rainforest leaves when expressed on an area basis and standardised to 25 °C (55.6 ± 2.6 and 106.5 ± 5.2 mmol m-2 s-1, for Vcmax and Jmax, respectively). However, when standardised to the mean ambient TMCF temperature of 12.5 °C, both photosynthetic parameters were much lower than ambient tropical rainforest Vcmax and Jmax values. The TMCF Jmax -Vcmax relationships were steeper than found in other tropical biomes, indicating a possible adaptation to the lower light availability in TMCFs because of frequent cloud cover, or a consequence of little atmospheric evaporative demand, which is also due to the humid conditions in this forest type. Although N-Vcmax relationships were significant (P<0.05), the fit was not very strong and the relationship between nitrogen use efficiency (NUE) and Vcmax indicates that TMCF species can be regarded as a different plant functional type compared with other tropical forest types. Diurnal measurements of net photosynthesis (A), stomatal conductance (gs) and leaf water potential (Yleaf) showed that different TMCF species experienced non-contrasting diurnal patterns of Yleaf and gs in the dry season. The observed patterns suggest that some TMCF species can be classified as isohydric species, while others behave anisohydrically. Additionally, in situ gs was not very responsive to these to the range of experienced photosynthetically active radiation (PAR), vapour pressure deficit (VPD) or soil water content (SWC), leading to the conclusion that in the studied TMCF, drought stress does not play a role in C-uptake. When using the measured photosynthetic parameters for up-scaling C-uptake to stand scale with a Soil-Plant-Atmosphere model, simulated annual gross primary productivity (GPP) was 16.24 ±1.6 T C ha-1 yr-1, which is about half the GPP observed in neotropical lowland rainforests. Analyses of the modelled results showed that GPP in this TMCF is mostly controlled by temperature, PAR and leaf area index (LAI) and when increasing these three factors to values found in tropical lowland forest, GPP increased up to 75%. In addition, the modelled results indicate that hydraulic limitations on TMCF C-uptake are very unlikely under current climatic conditions. The modelled results also showed that increases in radiation as a result of less cloud cover do not translate to straightforward increases of GPP. The cloudy conditions of TMCFs, which reduced incident PAR in TMCFs, should therefore not be regarded simply as a negative control on TMCF GPP. Instead, the increase in fraction of diffuse radiation partially offsets the decrease in GPP following the reduction in PAR. Overall, the results of this study show that leaves of Andean TMCF forests have similar C-uptake capacity to tropical lowland rainforests when standardized to similar temperatures, but that for in situ C-uptake temperature, radiation and LAI are the key controls.
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Rombo, Oskar. "Software Benchmark and Material Selection in an Exhaust Manifold : Thermo-mechanical fatigue simulation of an exhaust manifold in AVL Fire M." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68662.
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Today, there is a great focus on downsizing the engines, this means that the engines are made smaller in size but retain the same power. This in combination with the drive to increase the power of the engines has led to the engine components being exposed to high thermal loads. Today’s engines also use very high cylinder pressure. The high thermal loads in combination with the high cylinder pressure have led to that the engine components are often very close to their material limits, so close that damage is common. This places high requirements on the materials, which makes the material selection a critical part of the engineering process.The main focus in this thesis work has been to develop and investigate a FEM model that can be used to quickly evaluate materials in an exhaust manifold that is exposed to thermo-mechanical fatigue (TMF). The model was then used to verify a material selection made for an existing exhaust manifold. One of AVL’s own software programs has also been evaluated, to see if it is a viable alternative to ABAQUS when preforming TMF simulations.The material selection made in this master thesis had the restriction that the exhaust manifold should not fail due to low cycle fatigue (LCF) when exposed to TMF. The goal has been to minimize the mass of the exhaust manifold by selecting a strong material with low density. The reason for this is because today there is a big focus on energy efficient cars with low emission levels. The simplest way to achieve this is to minimize the mass of the vehicle.The simulations conducted in this work has been performed in two different software’s, ABAQUS and AVL Fire M. In AVL Fire M flow simulations and steady-state heat transfer simulations have been performed. In ABAQUS, steady-state and transient heat transfer simulations and stress-strain simulations have been performed.The material selection process showed that Inconel 601 is the most suitable material for an exhaust manifold exposed to TMF. The simulations using Inconel 601 showed that this material will not fail due to LCF.The FEM model that was developed in this thesis was a lot faster compared to the existing TMF model used at AVL.CPU time for the existing model: 14 days 13 hours 14 minutes and 30 seconds (Core time).CPU time for the model developed in this thesis: 1 day 6 hours 37 minutes and 49 seconds (Core time).Two alternative models have been proposed for TMF simulations, one that uses the model developed in this thesis and one that is a combination of the existing model and the model developed in this work.
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Joiner, Josiah W. "Investigation into the Impact of Hold Time, Thermal Mechanical Fatigue, Shotpeen, and Retardation on Fatigue Crack Growth in Inconel Dovetail Slots in Jet Engines." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1314044883.
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FAVORETO, R. C. "Uma Proposta de Solução para Levantamento do Inventário dos Elementos de Rede em Redes Ópticas de Transporte." Universidade Federal do Espírito Santo, 2014. http://repositorio.ufes.br/handle/10/9648.
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Previous issue date: 2014-08-22As demandas por serviços de telecomunicações multimídia, garantia de QoS (Quality of Service) e mecanismos de gerenciamento e controle direcionam a evolução da rede de núcleo para adoção da tecnologia OTN (Optical Transport Network) como solução de rede de transporte. Para conduzir a evolução da tecnologia OTN a ITU-T (International Telecommunication Union Telecommunications Standardization Sector) estabelece uma série de recomendações, dentre elas, as específicas para o plano de gerenciamento de redes. Essas, por sua vez, apresentam deficiências no que se referem ao levantamento do inventário dos objetos gerenciados definidos pelas normas da ITU-T. A ITU-T define a representação dos elementos de rede em caráter funcional, mais especificamente como módulos de Funções Atômicas. Contudo, a falta de clareza na implementação das Funções Atômicas e a carência de integração com as representações físicas dos elementos de rede implica na omissão, por parte dos diversos fabricantes, da implementação dos mecanismos recomendados em norma. Esta dissertação tem como objetivo geral apresentar uma proposta de solução para o levantamento do inventário dos elementos de rede em redes OTN abrangendo de forma integrada as representações funcional e física do elemento de rede, além de possibilitar aos diversos fabricantes a aderência às normas da ITU-T bem como oferecer ao operador de rede a configuração dos componentes de uma forma mais intuitiva.
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Stone, Philippa Mary Rose. "Response of rainforest trees to climate warming along an elevational gradient in the Peruvian Andes." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31560.
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The tropical rainforests of the Peruvian Andes are some of the most biodiverse and most vulnerable to climate warming in the world. The Andes are predicted to experience substantial increases in warming of between +2 °C to +5 °C by the end of the century, in addition to an increases in the frequency of high temperature extremes, drought and flood events. The response of these forests to climate change over the next century has global relevance, due to the high levels of endemic species present and the potential role these areas will play as refugia for lowland species. Despite this, the response of tropical montane forests (TMCFs) to climate change remains under-studied. Our current understanding of how Andean species will respond to climate change is based on studies of past compositional changes. Upslope shifts in plant communities of approximately 1.2 - 2.0 m·y-1 have been observed along elevational gradients within Central and South America over the last decade. Based on these migration rates, it has been estimated that the majority of communities will lag behind increases in temperature by 5.5 °C by the end of the century. The implications of this for populations at the trailing range edge is unclear, due to a lack of mechanistic data concerning the acclimatory limits of rainforest species. When faced with rapid warming plant species will need to rapidly adapt, acclimate or migrate in order to survive. In the case of Andean species, migration rates may not be sufficient for a species to remain within its optimal thermal niche and adaptive responses will likely be too slow to be effective, hence individuals will have to acclimate in situ to prevent a decline in performance. The acclimatory ability of species can be quantified by measuring changes in performance, leaf physiology and anatomy in response to experimental manipulations of climate, however such studies are rare within the tropics. Here we carried out a seedling transplant experiment, utilising an extensive 400-3500 m asl elevational gradient in the Peruvian Andes, to simulate climate warming and upslope migration of tree seedlings under real-world conditions. To provide context for the transplant study, natural variation in leaf anatomical traits and physiological stress were explored for twelve species belonging to lowland (LF), mid-elevation (LMF) and tropical montane cloud forest communities. Adults and seedlings from the centre and furthest-most extent of each species' elevational range were studied and compared. Seedlings of each elevational forest community were transplanted downslope and upslope of their local elevational range by the equivalent of ±2 °C and ±4 °C in mean annual temperature. The experiment followed the transplanted seedlings of eleven species over a one year period, monitoring survival, growth and physiological stress (Fv/Fm) of individuals. The acclimatory ability of a subset of these species was quantified by measuring changes in photosynthetic capacity (Vcmax and Jmax), respiratory capacity (Rd) and anatomical traits (Na, Pa, LMA, LDMC) in response to transplantation. The results showed that within the natural population there was little evidence of leaf trait acclimation to elevational shifts in climate, but also little evidence of physiological stress at the trailing range edge. There were however differences in the leaf trait strategies employed by each elevational community, increasing in abiotic stress-tolerance with elevation. Physiological stress was greatest in the seedling population and, unlike the adult population, increased slightly at the trailing edge. This indicated that seedlings were more vulnerable to warming than their adult counterparts and at mid-elevations TMCF seedlings were more vulnerable than LMF seedlings. Seedling survival and growth declined in response to transplantation away from the home elevation for the majority of species, with upslope declines as a result of abiotic limitations, and downslope declines due to biotic limitations. All seedlings were found to be able to acclimate their respiratory capacity in response to transplantation, however this was not the case for photosynthetic capacity. LMF species performed significantly better than TMCF seedlings with transplantation, demonstrating a greater acclimatory capacity for photosynthesis. LMF species were able to adjust Jmax in order to maintain rates at ambient temperatures, but were not able to upregulate Vcmax upslope, whereas TMCF species were not able to respond in either transplant direction. Overall, these findings suggest that under moderate warming scenarios LMF species will have a competitive advantage over TMCF species at mid-elevations, gradually expanding their range into TMCF species' habitat over the next century. As a result of this and due to the slow pace of upslope migration, we predict that TMCF species will undergo range retractions and possible extinctions. The speed of this response will be determined by the trajectory of future warming and the frequency of extreme climatic events.
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Ek, David. "Material parameter study for aheavy-vehicle exhaust manifoldusing the finite element method : to increase component lifetime and decrease its environmental impact." Thesis, Linköpings universitet, Konstruktionsmaterial, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-165869.
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The thesis originates from a need to meet stricter environmental regulations for Scania, to reduce fuel consumption and emission from heavy-vehicles. Scania aims to fulfil these requirements by increasing combustion pressure and temperature. These conditions are tougher for the engine components and they shorten their lifetime. This thesis aims to improve Scania’s ability to increase the lifetime of a heavy-vehicle exhaust manifold, an engine component that collects exhaust from several engine cylinders into one pipe. This was done by conducting a material comparison and a parameter study, both used the FEM software Abaqus CAE. The material comparison consisted of three ferritic and austenitic ductile cast irons (SiMo51, SiMo1000 and Ni-resist) subjected to thermal stress. Their max stress was compared for two thermo-mechanical fatigue cases, out-of-phase and in-phase. A parameter study was also conducted to clarify the influence of thermal conductivity, thermalexpansion, Young’s modulus and yield strength on max stress for OP and IP in the exhaust manifold. The FEM simulation results from the parameter study were used to create functions that can be used to decide how to treat/process a material to minimise the stress in the exhaust manifold. They can also be used in material selection to choose a material that minimises stress. The research questions and their shortened answers can be seen below. 1. Which of SiMo51, SiMo1000 and Ni-resist produces the lowest tensile stresses? ForOP, SiMo1000 produced a slightly lower max principal stress than SiMo51. For IP, Ni-resistproduced the lowest max principal stress by a large margin. 2. How do different material properties affect the maximum stress during operation of thegiven component? Thermal conductivity has a decreasing relation to max stress. Thermalexpansion and Young’s modulus have a similar relation to max stress, stress increases forboth properties as they increase. A decreased yield strength decreases the max stress forstresses above the yield limit but has no effect on stress below it. 3. How should an objective function to minimise max stress in the component with regard to material properties be expressed? functions of OP and IP can be seen in the actual abstract.
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Niemietz, Kathrin. "Untersuchung zur elektromagnetischen Strömungskontrolle mittels externer Magnetfelder bei der VGF-Kristallzüchtung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-129939.
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Die vorliegende Arbeit beinhaltet die Kontrolle und Beeinflussung der Schmelzströmung beim Vertical Gradient Freeze- (VGF-) Verfahren durch magnetische Wechselfelder, wobei speziell der Einfluss von rotierenden und wandernden Magnetfeldern auf den Stoff- und Wärmetransport untersucht wird. Das Potential der VGF-Magnetfeldzüchtung für die Reduktion der thermischen Spannungen bei der Züchtung von Ge- und GaAs-Kristallen wird demonstriert. Anhand von Experimenten zur Gasphasendotierung von Ge-Einkristallen mit Zink werden außerdem die Vorteile des Magnetfeldeinsatzes für eine effektive Durchmischung der Schmelze und für eine Reduzierung der radialen Dotierstoffsegregation gezeigt. Ein weiterer Schwerpunkt der Arbeit ist die Entwicklung von züchtungsrelevanten Modellanordnungen für systematische Strömungsexperimente mit niedrig schmelzenden Legierungen. Dadurch kann die gegenseitige Beeinflussung zwischen der magnetfeldinduzierten Strömung und der thermische Auftriebströmung beim VGF-Verfahren direkt untersucht werden.
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Fall, Niklas, and Viktor Hammar. "Design of Perimeter Walls in Tubed Mega Frame Structures." Thesis, KTH, Betongbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147242.
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The Tubed Mega Frame is a new concept for constructing high-rise buildings,based on the idea of moving the main bearing system to the perimeter of thebuilding by using a number of large hollow columns, mega tubes, connected byperimeter walls at certain levels. The concept is under development by Tyréns ABand has not yet been implemented in reality. This thesis is part of the ongoing workprocess and has the aim of shedding light on the issues and problems with the newconcept when it comes to the perimeter walls. The perimeter walls are an essential part of the Tubed Mega Frame structure sincethey provide the main lateral stability of the structure by connecting the mega tubesand transferring lateral loads between them. It is therefore of big importance thatthe walls are designed and constructed to withstand all the loads they wouldpossibly be exposed to.In this thesis a perimeter wall in a prototype building of the Tubed Mega Framehave been analysed, designed and tested using non-linear FE-analysis in the pursuitof create a better understanding in how the perimeter walls works and should bedesigned. To begin with, a global analysis was performed to obtain the forces acting on themost critical perimeter wall. The stresses in the wall were then analysed in order tocreate an appropriate strut-and-tie model used to determine the reinforcementdesign for the specified perimeter wall. The perimeter wall was designed for amaximum shear force of 14.5 MN and corresponding moment of 87 MNm usingstrut-and-tie model according to American standards, ACI 318-11. The final step was to verify the design using the non-linear FE-analysis programATENA. A model of the reinforced wall was analysed with two different loadcases; one were the resistance was determined by unidirectional deformation untilfailure and one were the effects of cyclic loading was considered by initialdeformation corresponding to service loads prior to failure loading. The resistanceobtained from the first load case was 46.8 MN and for the second 19.1 MN usingmean values for material properties. In order to obtain a design resistance of the wall in the non-linear analysis, a globalsafety factor was determined by using the ECOV method. The design resistance were 39.9 and 13.5 for the two load cases respectively.Tubed Mega Frame (TMF) är ett nytt koncept för att bygga höghus som bygger påidén om att flytta det bärande systemet till omkretsen av byggnaden med hjälp avett antal stora ihåliga pelare, megatuber, anslutna med omslutande tvärväggar påvissa våningsplan. Konceptet är under utveckling av Tyréns AB och har ännu integenomförts i verkligheten. Detta examensarbete är en del i den pågående processenoch målet är att belysa frågor och problem som finns med det nya konceptet närdet gäller de omslutande tvärväggarna. De omslutande tvärväggarna är en vital del av Tubed Mega Frame eftersom debidrar till huvudsakliga sidostabiliteten i byggnaden genom att sammankopplamegatuberna och överföra horisontalkrafter mellan dem. Det är därför av stor viktatt väggarna är konstruerade och tillverkade för att stå emot alla de belastningarsom de skulle kunna vara utsatta för. I detta examensarbete har en tvärvägg i en prototypbyggnad för Tubed MegaFrame analyserats, dimensionerats och testats med syftet att bidra till en bättreförståelse för hur tvärväggarna fungerar och bör utformas. Till att börja med har en global analys utförts för att erhålla de krafter som verkarpå den mest kritiska tvärväggen. Spänningarna i väggen analyserades sedan för attskapa en lämplig fackverksmodell som sedan användes för att bestämmaarmeringsutformning för den specificerade tvärväggen. Väggen dimensioneradesför en maximal tvärkraft på 14,5 MN och ett motsvarande moment på 87 MNmgenom att använda fackverksmetoden enligt amerikanska standarder, ACI 318-11. Det sista steget var att kontrollera konstruktionen med hjälp av det ickelinjära FE-analysprogrammet ATENA. En modell av den armerade väggen analyserades medtvå olika lastfall. I det första lastfallet genom att i en riktning deformera väggen tillbrott. I det andra lastfallet beaktades tidigare uppsprickning genom att först belastaväggen med en deformation motsvarande dess brukslast och sedan belasta väggen imotsatt riktning tills brott uppstod. Bärförmågan var 46,8 MN och 19,1 MN förrespektive lastfall, beräknat med medelvärden för materialegenskaper. För att erhålla en dimensionerande bärförmåga för väggen ur den ickelinjäraanalysen bestämdes en global säkerhetsfaktor med hjälp av ECOV-metoden.Dimensionerande bärförmåga var 39,9 MN och 13,5 MN för respektive lastfall.
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Roth, Marcel. "Verhalten und Lebensdauer einer intermetallischen Legierung auf Basis von gamma-TiAl unter thermomechanischer Beanspruchung." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2010. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-39685.
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Die Eigenschaften der kommerziell verfügbaren Hochtemperaturwerkstoffe bestimmen den Wirkungsgrad und die Leistungsfähigkeit von Flug- und Industriegasturbinen sowie Motoren. Da die breit eingesetzten Nickelbasis-Werkstoffe mit etwa 8-8,5 g/cm^3 eine verhältnismäßig hohe Dichte aufweisen, wird seit Jahrzehnten nach alternativen Werkstoffen gesucht. Da besonders die Titanaluminide, speziell die stark Nb-haltigen gamma-TiAl-Legierungen (TNB-Legierungen), mit einer Dichte von ca. 4,5 g/cm^3 einen beträchtlichen Dichtegewinn gegenüber den Nickelbasis-Superlegierungen bieten, haben Legierungen auf dieser Basis das größte Potenzial, um die Nickelbasis-Superlegierungen teilweise zu ersetzen. Im Fluggasturbinenbau ist die Anwendung für den hinteren Teil des Hochdruckverdichters und die letzten Stufen der Turbine angedacht. Dabei sollen Schaufeln, Gehäuse und Anbauteile aus modernen gamma-TiAl-Legierungen zum Einsatz kommen. Für die Auslegung dieser Bauteile sind umfassende Kenntnisse des Werkstoffverhaltens zwingend notwendig. Treten im Betrieb hohe Temperaturgradienten in den Bauteilen auf, so muss besonders auch das thermomechanische Ermüdungsverhalten betrachtet werden. Dieses stellt insbesondere für den Einsatz in Gasturbinen einen relevanten Schädigungsmechanismus dar.
Inhalt dieser Arbeit war die Charakterisierung des thermomechanischen Verformungs- und Ermüdungsverhaltens der modernen gamma-TiAl-Legierung TNB-V5. Dabei wurden die Einflüsse der Mikrostruktur, der Phasenbeziehung zwischen thermischer und mechanischer Beanspruchung, des Temperaturbereiches und der Höhe der mechanischen Beanspruchung untersucht. Zum Verständnis der Ergebnisse wurden moderne Methoden der Mikrocharakterisierung angewandt. Zur Beschreibung des Lebensdauerverhaltens wurden der Schädigungsparameter PSWT nach Smith, Watson und Topper und der Schädigungsparameter PHL nach Haibach und Lehrke erfolgreich angewandt. Es wurden folgende, wesentlich über den bisherigen Stand des Wissens hinausgehende Erkenntnisse gewonnen:
Eine Beanspruchung mit der Phasenbeziehung Clockwise-Diamond (CD) bzw. Counter-Clockwise-Diamond (CCD) führt im Gegensatz zur In-Phase- (IP) oder Out-of-Phase- (OP) Beanspruchung nur zu geringen Unterschieden zwischen den Beträgen der Ober- und der Unterspannung. Unter CD- und CCD-Beanspruchung kommt es zu nahezu keinen bzw. im Vergleich zur IP- und OP-Beanspruchung deutlich geringeren Zug- oder Druckmittelspannungen. Des Weiteren unterscheiden sich die Spannungs-Dehnungs-Hysteresekurven unter CD- bzw. CCD-Beanspruchung nur sehr wenig. Die Bruchlastspielzahlen der CD- und CCD-Versuche liegen immer zwischen denen der IP- und OP-Versuche.
Für eine Lebensdauervorhersage unter thermomechanischer Beanspruchung sind die Schädigungsparameter PSWT nach Smith, Watson und Topper und PHL nach Haibach und Lehrke gut geeignet, wenn der Versuchs- bzw. Anwendungstemperaturbereich Temperaturen oberhalb des Spröd-Duktil-Überganges (ca. 750°C) beinhaltet. Ist dies der Fall, dann weichen die experimentell ermittelten Lebensdauern im betrachteten Bereich (Bruchlastspielzahl ca. 50 – 3000) maximal um den Faktor ±3 von den vorhergesagten Werten ab.
Der Einfluss der Mikrostruktur auf das zyklische Verformungs- und Ermüdungsverhalten ist unter den betrachteten Bedingungen überraschend gering. Die Mikrostrukturen Near-Gamma und Duplex zeigen unter allen Versuchsbedingungen vergleichbare Lebensdauern, während das Fully-Lamellar-Gefüge tendenziell etwas höhere Lebensdauern aufweist.
Weiterhin stellen die gewonnenen Ergebnisse eine wertvolle Datenbasis für die Auslegung von thermomechanisch beanspruchten Komponenten im Turbinen- und Motorenbau dar.
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Karl, Justin. "Thermomechanical Fatigue Life Prediction of Notched 304 Stainless Steel." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5796.
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The behavior of materials as they are subjected to combined thermal and mechanical fatigue loads is an area of research that carries great significance in a number of engineering applications. Power generation, petrochemical, and aerospace industries operate machinery with expensive components that undergo repeated applications of force while simultaneously being exposed to variable temperature working fluids. A case of considerable importance is found in steam turbines, which subject blades to cyclic loads from rotation as well as the passing of heated gases. The complex strain and temperature histories from this type of operation, combined with the geometric profile of the blades, make accurate prediction of service life for such components challenging. Development of a deterministic life prediction model backed by physical data would allow design and operation of turbines with higher efficiency and greater regard for reliability. The majority of thermomechanical fatigue (TMF) life prediction modeling research attempts to correlate basic material property data with simplistic strain and thermal histories. With the exception of very limited cases, these types of efforts have been insufficient and imprecise in their capabilities. Early researchers did not account for the multiple damage mechanisms that operate and interact within a material during TMF loads, and did not adequately address the extent of the relationship between smooth and notched parts. More recent research that adequately recognizes the multivariate nature of TMF develops models that handle life reduction through summation of constitutive damage terms. It is feasible that a modification to the damage-based approach can sufficiently include cases that involve complex geometry. The focus of this research is to construct an experimentally-backed extension of the damage-based approach that improves handling of geometric discontinuities. Smooth and notched specimens of Type 304 stainless steel were subjected to several types of idealized fatigue conditions to assemble a clear picture of the types of damage occurring in a steam turbine and similarly-loaded mechanical systems. These results were compared with a number of idealized TMF experiments, and supplemented by numerical simulation and microscopic observation. A non-uniform damage-summation constitutive model was developed primarily based on physical observations. An additional simplistic model was developed based on phenomenological effect. Findings from this study will be applicable to life prediction efforts in other similar material and load cases.Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
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Barker, Vincent Mark. "Thermo-mechanical fatigue crack growth modeling of a nickel-based superalloy." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44714.
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A model was created to predict the thermo-mechanical fatigue crack growth rates under typical engine spectrum loading conditions. This model serves as both a crack growth analysis tool to determine residual lifetime of ageing turbine components and as a design tool to assess the effects of temperature and loading variables on crack propagation. The material used in the development of this model was a polycrystalline superalloy, Inconel 100 (IN-100).
The first step in creating a reliable model was to define the first order effects that influence TMF crack growth in a typical engine spectrum. Load interaction effects were determined to be major contributors to lifetime estimates by influencing crack growth rates based upon previous load histories. A yield zone model was modified to include temperature dependent properties that controlled the effects of crack growth retardation and acceleration based upon overloads and underloads, respectively. Multiple overload effects were included in the model to create enhanced retardation compared to single overload tests. Temperature interaction effects were also considered very important due to the wide temperature ranges of turbine engine components. Oxidation and changing temperature effects were accounted for by accelerating crack growth in regions that had been affected by higher temperatures. Constant amplitude crack growth rates were used as a baseline, upon which load and temperature interaction effects were applied. Experimental data of isolated first order effects was used to calibrate and verify the model.
Experimental data provided the means to verify that the model was a good fit to experimental results. The load interaction effects were described by a yield zone model, which included temperature dependent properties. These properties were determined experimentally and were essential in the model's development to include load and temperature contributions. Other interesting factors became apparent through testing. It was seen that specific combinations of strain rate and temperature would lead to serrated yielding, discovered to be the Portevin-Le Chatelier effect. This effect manifested itself as enhanced hardening, leading to unstable strain bursts in specimens that cyclically yielded while changing temperature.
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Bouchenot, Thomas. "A Simplified Approach to Thermomechanical Fatigue and Application to V-shaped Notches." Honors in the Major Thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/939.
Full textAbstract:
A vast array of high value parts in land- and air-based turbomachinery are subjected to non-isothermal cycling in the presence of mechanical loading. Crack initiation, growth and eventual failure more significantly reduce life in these components compared to isothermal conditions. More accurate simulation of the stress and strain evolution at critical locations of components, as well as test specimens, can lead to a more accurate prediction of remaining life to a structural integrity specialists. The focus of this thesis is to characterize the effects of thermomechanical fatigue (TMF) on generic turbomachinery alloy. An expression that can be used to estimate the maximum and minimum stress under a variety of loading conditions is formulated. Analytical expressions developed here are modifications of classic mechanics of materials methods (e.g. Neuber's Rule and Ramberg-Osgood). The novel models are developed from a collection of data based on parametric finite element analysis to encompass the complex load history present in turbine service conditions. Relevance of the observations and formulated solutions are also explored for the case of a tensile specimen containing a v-shaped notch. Accurate estimations of non-isothermal fatigue presented here endeavor to improve component lifing and decrease maintenance costs.B.S.M.E.
Bachelors
Engineering and Computer Science
Mechanical Engineering
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Oudin, Alexis. "Fatigue thermo-mécanique d'aciers pour outils de travail à chaud." Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1091.
Full textAbstract:
L'endommagement par fatigue thermique limite la durée de vie des outils de mise en forme à chaud. Un essai de Fatigue Thermo-Mécanique (TMF) est développé pour étudier cet endommagement sur les aciers pour travail à chaud 55NiCrMoV7 et X38CrMoV5. Des cycles TMF hors-phase compression- compression avec différentes températures minimales et maximales sont étudiés. Le comportement cyclique des deux aciers est caractérisé par deux régimes successifs d'accommodation (adaptation progressive de la microstructure à la sollicitation TMF) et d'adoucissement (diminution cyclique de la résistance de l'acier). La température maximale contrôle le comportement. Pour l'acier X38CrMoV5, au dessus de la température critique 550°C, des processus thermiquement activés contrôlent le comportement cyclique. L'acier 55NiCrMoV7 présente une accommodation plus rapide et globalement un plus fort adoucissement que l'acier X38CrMoV5. L'oxydation préférentielle suivie de la fissuration par fatigue-oxydation semble être le mécanisme majeur de l'amorçage de fissure. Une loi parabolique décrit la cinétique de croissance de la couche d'oxyde plus importante pour l'acier 55NiCrMoV7. Pour l'acier X38CrMoV5, une loi de fissuration de la couche d'oxyde est proposée. La propagation de fissure en TMF est déduite des stries de fatigue. Un facteur d'intensité de déformation et une loi de type Paris décrivent la propagation de fissure. Pour les lois d'oxydation et de propagation, l'effet de la température minimale est négligé. Les durées de vie TMF diminuent avec l'augmentation de la température maximale. Une loi phénoménologique simple de type Manson-Coffin basée sur la variation de déformation mécanique est proposée. Une description ¯ne de la durée de vie TMF est utilisée. Pour l'acier X38CrMoV5, les lois de fissuration de la couche d'oxyde et de propagation de fissure sont utilisées pour estimer certaines fractions de la durée de vie. L'acier X38CrMoV5 présente globalement une plus grande résistance TMF que l'acier 55NiCrMoV7Thermal fatigue damage is a life limiting factor of hot metal forming tools. A Thermo-Mechanical Fatigue (TMF) facility was developed to assess such damage mechanisms on the 55NiCrMoV7 and X38CrMoV5 hot work tool steels. A full compressive out-of-phase TMF cycle with different minimal and maximal temperatures were examined. The cyclic behaviour of both steels is characterised by two successive regimes of accommodation and softening. Accommodation is a gradual adaptation of the microstructure to TMF loading while softening corresponds to a cyclic decrease of the steel strength. The maximal temperature controls the cyclic behaviour. For the X38CrMoV5 steel, the temperature 550°C constitutes a boundary above which thermally activated phenomena control the cyclic behaviour. The 55NiCrMoV7 steel showed more rapid accommodation and global higher softening than the X38CrMoV5 steel. Preferential oxidation and oxidation-fatigue cracking seem to be the dominant crack initiation mechanisms. A parabolic law describes the oxide scale thickness growth higher for the 55NiCrMoV7 steel. For the X38CrMoV5 steel, an oxide scale through thickness cracking law was proposed. The TMF crack growth rate was deduced from striations accounting. A strain intensity factor range and a Paris law type were used to correlate the crack growth rate. The oxidation, tensile going strain and cyclic plasticity seem to control the crack growth. For the oxidation and the crack growth laws, the minimal temperature effect is neglected. The TMF lives are reduced with maximal temperature rise. A simple phenomenological TMF life prediction model was proposed using the Manson-Coffin relationship mechanical strain range based. A detailed partitioning of the fatigue life was proposed. For the X38CrMoV5 steel, the oxide scale through thickness cracking and the crack growth laws were used to estimate some fractions of the TMF life. The X38CrMoV5 steel presents a global better TMF strength than the 55NiCrMoV7 steel
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Vila, Currius Mireia. "Avaluació de la utilitat del monitoratge farmacocinètic dels fàrmacs anti-TNF en pacients amb malaltia inflamatòria intestinal en dos hospitals amb diferent grau d’especialització." Doctoral thesis, Universitat de Girona, 2020. http://hdl.handle.net/10803/670009.
Full textAbstract:
The tumor necrosis factor (TNF) acts as a potent inducer of inflammation in autoimmune diseases like Crohn disease and ulcerative colitis. Current available treatments are based on TNF inhibition such as infliximab and adalimumab. These drugs are very effective in inducing and maintaining remission. However, there is a high proportion of patients that lose their initial response over time. Recently, some studies have used therapeutic anti-TNF monitoring tools in order to adjust treatments according to each patient.
We have conducted a prospective multicenter study to determine the usefulness of therapeutic anti-TNF monitoring in patients with Crohn disease or ulcerative colitis in two centers with a different degree of specialization.
The results have allowed us to assess the clinical and economic impact of therapeutic anti-TNF monitoring in each center. Moreover, they have let us to determine which variables might influence the pharmacokinetics of these anti-TNF drugsEl factor de necrosi tumoral (TNF) actua com un potent inductor de la inflamació en la malaltia de Crohn (MC) i colitis ulcerosa (CU). Pel tractament d’aquestes malalties existeixen fàrmacs anti-TNF com Infliximab i Adalimumab, medicaments efectius per induir i mantenir la remissió encara que una alta proporció de pacients deixen de respondre al llarg del temps. Darrerament, alguns estudis han començat a utilitzar l’eina de la determinació de nivells de fàrmac per ajustar les pautes de tractament en funció de cada pacient. Durant aquesta tesi doctoral hem realitzat un estudi pilot multicèntric prospectiu per determinar la utilitat del monitoratge farmacocinètic de fàrmacs anti-TNF en pacients amb MC o CU en dos centres amb diferent grau d’especialització. Els resultats ens han permès determinar l’impacte clínic i econòmic que representa el monitoratge farmacocinètic de fàrmacs anti-TNF a cada hospital i determinar les variables que afecten a la farmacocinètica d’aquests fàrmacs
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Petráš, Roman. "Únavová odolnost a mechanizmy únavového poškození v materiálech pro vysoké teploty." Doctoral thesis, Vysoké učení technické v Brně. CEITEC VUT, 2021. http://www.nusl.cz/ntk/nusl-433631.
Full textAbstract:
Superaustenitická korozivzdorná ocel typu 22Cr25NiWCoCu určená pro vysokoteplotní aplikace v energetickém průmyslu byla studována za podmínek nízkocyklové únavy při pokojové a zvýšené teplotě. Jednotlivé vzorky byly podrobeny různým zátěžným procedurám, což umožnilo studium materiálové odezvy spolu s mechanismem poškození. Křivky cyklického zpevnění/změkčení, cyklického napětí a Coffin-Mansonovy křivky byly vyhodnoceny. Únavová životnost materiálu byla diskutována s ohledem na uplatňované mechanismy poškození, které se vyvinuly za specifických zátěžných podmínek. Standardní izotermální únavové experimenty byly provedeny při pokojové a zvýšené teplotě. Hysterezní smyčky zaznamenané během cyklického zatěžování byly analyzovány pomocí zobecněné statistické teorie hysterezní smyčky. Pro různé amplitudy napětí byla určena jak distribuce hustoty pravděpodobnosti interních kritických napětí (dále PDF), tak rovněž zjištěn její vývoj během cyklického namáhání. Zjištěné průběhy PDF byly korelovány s vývojem povrchového reliéfu a vnitřního dislokačního uspořádání zdokumentované pro obě teploty pomocí rastrovací elektronové mikroskopie (SEM) vybavené technikou fokusovaného iontového svazku (FIB), která umožnila rovněž efektivní studium nukleace povrchových únavových trhlin. Při cyklickém zatížení při pokojové teplotě byla pozorována lokalizace cyklické plastické deformace do perzistentních skluzových pásů (PSP). V místech, kde tyto PSP vystupují na povrch materiálu byly pozorovány perzistentní skluzové stopy (PSS) tvořené extruzemi a intruzemi. Postupné prohlubování intruzí, zejména na čele nejhlubší intruze, vede k iniciaci únavové trhliny. Odlišný mechanismus tvorby trhlin byl zjištěn při únavové zkoušce při zvýšené teplotě, kde zásadní roli hrál vliv prostředí. Rychlá oxidace hranic zrn a jejich následné popraskání představuje dominantní mechanismus v I. stádiu nukleace trhlin. Aplikace desetiminutové prodlevy v tahové části zátěžného cyklu vedlo k vývoji vnitřního (kavitačního) poškozování. Mechanismy vnitřního poškozování byly studovány na podélných řezech rovnoběžných s napěťovou osou zkušebních vzorků. Trhliny a jejich vztah k hranicím zrn a dvojčat byly studovány pomocí difrakce zpětně odražených elektronů (EBSD). Vliv prodlevy na únavovou životnost byl korelován s vývojem povrchového reliéfu a vnitřního poškození. Vzorky z uvedené oceli byly rovněž podrobeny zkouškám termomechanické únavy (TMF), při nichž se v čase mění jak zátěžná síla tak i teplota. Termomechanické únavové zkoušky v režimu soufázném (in-phase) a protifázném (out-of-phase) byly provedeny jak s prodlevou, tak i bez ní. Ve všech případech bylo pozorováno rychlé cyklické zpevnění bez ohledu na použitou amplitudu deformace, u vzorků testovaných v out-of-phase režimu byla zjištěna tendence k saturaci. Zkoumáním povrchového reliéfu za pomocí technik SEM a FIB byla odhalena přednostní oxidace hranic zrn a následné praskání těchto hranic kolmo k ose zatížení. Prodlevy v cyklech při maximálním napětí vedly ke zvýšení amplitudy plastické deformace a následně ke creepovému poškození ve formě vnitřních kavit a trhlin. Interkrystalické šíření trhlin bylo pozorováno na vzorcích testovaných v režimu in-phase. Vývoj poškození v režimu out-of-phase nebyl principiálně ovlivněn zařazením prodlevy do zátěžného cyklu. Charakteristickým znakem namáhání v režimu out-of-phase je nukleace několika trhlin v homogenní oxidické vrstvě jdoucích napříč zrny kolmo k ose zatěžování.
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Beckstein, Pascal. "Methodenentwicklung zur Simulation von Strömungen mit freier Oberfläche unter dem Einfluss elektromagnetischer Wechselfelder." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232474.
Full textAbstract:
Im Bereich der industriellen Metallurgie und Kristallzüchtung treten bei zahlreichen Anwendungen, wo magnetische Wechselfelder zur induktiven Beeinflussung von leitfähigen Werkstoffen eingesetzt werden, auch Strömungen mit freier Oberfläche auf. Das Anwendungsspektrum reicht dabei vom einfachen Aufschmelzen eines Metalls in einem offenen Tiegel bis hin zur vollständigen Levitation. Auch der sogenannte RGS-Prozess, ein substratbasiertes Kristallisationsverfahren zur Herstellung siliziumbasierter Dünnschichtmaterialien, ist dafür ein Beispiel. Um bei solchen Prozessen die Interaktion von Magnetfeld und Strömung zu untersuchen, ist die numerische Simulationen ein wertvolles Hilfsmittel. Für beliebige dreidimensionale Probleme werden entsprechende Berechnungen bisher durch eine externe Kopplung kommerzieller Programme realisiert, die für Magnetfeld und Strömung jeweils unterschiedliche numerische Techniken nutzen. Diese Vorgehensweise ist jedoch im Allgemeinen mit unnötigem Rechenaufwand verbunden. In dieser Arbeit wird ein neu entwickelter Methodenapparat auf Basis der FVM vorgestellt, mit welchem sich diese Art von Berechnungen effizient durchführen lassen. Mit der Implementierung dieser Methoden in foam-extend, einer erweiterten Version der quelloffenen Software OpenFOAM, ist daraus ein leistungsfähiges Werkzeug in Form einer freien Simulationsplattform entstanden, welches sich durch einen modularen Aufbau leicht erweitern lässt. Mit dieser Plattform wurden in foam-extend auch erstmalig dreidimensionale Induktionsprozesse im Frequenzraum gelöst.
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Palos, Daniel Afonso. "Estudo de Curvas de Coalescência e de Curvas de Diluição de Polímeros." Master's thesis, 2015. http://hdl.handle.net/10362/52368.
Full textAbstract:
presente dissertação para a obtenção do grau de Mestre em Engenharia Química e Bioquímica foi realizada no âmbito de um estágio no Laboratório de Controlo e Qualidade da empresa Resiquímica, Resinas Químicas, S.A.
O objectivo desta dissertação foi o estudo das curvas de diluição e das curvas de coalescência de resinas alquídicas e de dispersões aquosas.
As curvas de diluição são muito importantes a nível económico tanto para o cliente como para o produtor, visto que para o produtor é possível através destas curvas produzir uma resina a um custo mais baixo, e o cliente com estas curvas obtém a informação da quantidade de solvente necessário para diluir a resina para os valores de viscosidade pretendida.
As curvas de coalescência permitem-nos analisar a influência dos coalescentes na diminuição da temperatura mínima de formação de filme (TMFF) e a compatibilidade dos mesmos com as dispersões.
Do ponto de vista do produtor, estas curvas são importantes porque fornecem informação de quais os coalescentes que apresentam compatibilidade com as dispersões e qual a quantidade de coalescente necessário para baixar o TMFF o mais baixo possível.
Concluiu-se que os solventes que apresentam um melhor poder de solvência são das famílias das cetonas e ésteres, caso o cliente pretenda uma viscosidade muito baixa, mas com um teor em sólidos alto.
Concluiu-se também que os coalescentes que apresentam melhores resultados na diminuição do valor do TMFF são da família dos ésteres ou glicol ésteres, neste caso, os coalescentes B,C,E e F.
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Do, Ci-Fong, and 杜其峯. "Luminescence characteristics of sulfide phosphors synthesized with doping TmF3 and Mn." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/17062116931319074462.
Full textAbstract:
碩士國立高雄應用科技大學
電子工程系
99
There were two research subjects in this thesis, one was synthesis of CaS-based phosphor by solid-sate sintering method, and the other was preparation of ZnS-based phosphor by sol-gel method. In order to achieve white-light phosphor, the different activators such as the transition metals and the rare earth materials were doped to modify the luminescence color of the phosphor. The red-orange emission of ZnS:Mn,LiF phosphor shows the optimal photoluminescence property when it was doped with 0.5 mol% Mn and 0.3 mol% LiF, and aging at 75℃ for 6 h. The near white emission of CaS:Tm,LiF phosphor shows the optimal photoluminescence property when it was doped with 5 mol% Tm and 5 mol% LiF; which are sintered at 1000°C for 1.5 hour and annealed at 700°C for 1.5 hour. From the evaluation of phosphor characteristics with synthesis parameters of standing time, annealing temperature and time, and sintering temperature and time, it was found that the synthesis parameters indeed affected the particle size and luminescence intensity of the phosphor. The characteristics of the phosphors synthesized by sol-gel method and solid state reaction method were compared and discussed. Additionally, to achieve white-light emission, the red-orange and near white phosphors were mixed by different weight percentages, and the photoluminescence properties were analyzed.
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-Yu, Lo Jyue, and 羅玨瑜. "The Study of Service Quality , Imige and Consumer Satisfaction--The Case of TMFA." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/89424437885945818210.
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碩士國立臺北大學
企業管理學系
88
Abstract This study attempts to explore the relationship among service quality, institute image, and customer satisfaction, and constructs a integrated-evaluation model of service quality and customer satisfaction. In this empirical study of Taipei Fine Art Museum, The major findings are:1)There is a significant variances of expectation and perceived performance. 2) The measurement model of perceived performance is the best to forecast customer overall satisfaction. 3) There is a significant relationship of expectation and performance on the “professional and empathy” and “institute image” factors. 4) Institute image is more influence customer overall satisfaction than service quality. 5) There is a significant relation among customer overall satisfaction, revisit intention and suggest to someone. Keywords: Service Quality, Institute Image, Customer Satisfaction, and Museum
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Vanderherchen, Matthew Barton. "Trypsin modulating oostatic factor (TMOF) and non-peptidic analogs as novel insecticides and arthropod repellents." 2003. http://www.lib.ncsu.edu/theses/available/etd-03092003-192510/unrestricted/etd.pdf.
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Miller, Maria Romaine. "Synthesis and application of nine novel analogs of trypsin modulating oostatic factor (TMOF) in the mosquito, Aedes aegypti." 2000. http://www.lib.ncsu.edu/etd/public/etd-35401812810022551/etd.pdf.
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Eriksson, Anna-Maria. "Energieffektivisering av klimatskal med hänsyn till kulturhistorisk värdering : Fallstudier av tre befintliga småhus från 1900-talet ur bevarandesynpunkt." Thesis, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:du-16649.
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Allt hårdare lagkrav gör att det är svårt att energieffektivisera befintliga byggnader utan att förändra deras utseende. Syftet med examensarbetet är att utreda hur stor energieffektivisering, för tre befintliga småhus uppförda under 1900-talet, som är möjlig att uppnå genom förbättring av byggnadernas klimatskal, det vill säga tak, väggar, golv, fönster och dörrar, utan att förvanska byggnadernas utseende och samtidigt bevara deras kulturhistoriska värden. Arbetet bestod av en förstudie där tre byggnader identifierades, ett undersökningsskede där information om byggnaderna togs fram och ett slutsatsskede där energibesparande åtgärdsförslag togs fram och utvärderades. Byggnader som var goda representanter för sin tid och stil söktes. Byggnader från 1910-talet, 1930-talet och 1970-talet, lokaliserades. Sedan gjordes det fallstudier med intervjuer och inventeringar. För att utreda byggnadens klimatskal utfördes u-värdesberäkningar och energiberäkningar av befintliga byggander och byggnader baserade på föreslagna åtgärdsförslag. Ingen av byggnaderna nådde efter föreslagna åtgärder ner till passivhuskravet 59 kWh/år/m2 Atemp eller BBR-kravet 110 kWh/år/m2 Atemp för en byggnads specifika energianvändning. Den största möjliga energieffektivisering för de tre byggnaderna uppförda under 1900-talet, som är möjlig att uppnå utan att förvanska byggnadernas utseende och samtidigt bevara deras kulturhistoriska värden är 13,0 kWh/år/m2 Atemp, 49,7 kWh/år/m2 Atemp respektive 64,8 kWh/år/m2 Atemp. Slutsatser från arbetet är att byggnader från 1910-tal kan åtgärdas genom att isolera fönstren, sätta dit en extra dörr på insidan av ytterdörren samt tilläggsisolera snedtaket. Byggnader från 1930-tal kan åtgärdas genom att isolera fönstren med en isolerruta på insidan av fönstret och dörrarna med en extra dörr på insidan av ytterdörren. Byggnader från 1970-tal kan åtgärda fönstren genom att byta ut dem till energifönster, ingen åtgärd för golvet men fasaden isoleras utvändigt med vakuumisolering. Byggnaden från 1970-talet klarade sig bäst i jämförelsen eftersom den var i autentiskt skick från början vilket gjorde att förbättringen blev större än för till exempel byggnaden från 1910-talet som redan var ombyggd innan åtgärder föreslogs.Increasingly stringent legal requirements make it difficult to energy efficiency in existing buildings without changing their appearance. The purpose of the study is to investigate how much energy, for three existing single-family homes built in the 1900s, which is achievable by improving the building envelope, ie, ceilings, walls, floors, windows and doors, without distorting the building's appearance and while maintaining their cultural values. The work consisted of a pilot study where three buildings were identified, a research stage where information about the buildings were developed and an inference stage where energy saving measures proposed were developed and evaluated. Buildings that were good representatives of their time and style sought. Buildings from the 1910s, 1930s and 1970s, was located. Since it was done case studies, interviews and surveys. To investigate the building envelope was conducted U-value calculations and energy calculations of the existing building commitment and buildings based on the proposed policy proposals. None of the buildings reached after the proposed action down to the passive house requirement 59 kWh/year/m2 Atemp or BBR requirement 110 kWh/year/m2 Atemp for a building-specific energy consumption. The maximum possible energy efficiency for the three buildings erected during the 1900s, which is achievable without corrupting the buildings' appearance while preserving their cultural values is 13.0 kWh/year/m2 Atemp, 49.7 kWh/year/m2 Atemp respectively 64.8 kWh/year/m2 Atemp. Conclusions of the work is that buildings from the 1910's can be addressed by isolating the windows, put one extra door on the inside of the front door and additional insulation in sloping roof. Buildings from the 1930s can be addressed by isolating windows with insulating glass on the inside of the windows and doors with an extra door on the inside of the front door. Buildings from the 1970s can fix the windows by changing them into energy windows, no action on the floor but the facade insulated externally with vacuum insulation. The building from the 1970s fared best in the comparison because it was the authentic condition from the beginning, which meant that the improvement was greater than for example the building from the 1910s that was already rebuilt before action was proposed.
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Figueiredo, Sónia Filipa da Silva. "The importance of document management and the future of clinical trials archive." Master's thesis, 2018. http://hdl.handle.net/10316/84486.
Full textAbstract:
Dissertação de Mestrado em Biotecnologia Farmacêutica apresentada à Faculdade de FarmáciaO ensaio clínico é uma parte fundamental no desenvolvimento de um novo medicamento, fazendo a ponte entre a investigação científica e a clínica e, posteriormente, o mercado. A parte clínica de um ensaio tem uma duração restrita, cedendo o lugar aos documentos do arquivo, a fim de “contarem a história do ensaio”. São esses documentos que suportam o pedido de submissão às autoridades para introdução no mercado do produto teste; e estão disponíveis no momento de uma inspecção por parte das autoridades competentes. Com esta dissertação pretende-se fazer uma revisão acerca do arquivo de ensaios clínicos. A recolha de dados de forma eletrónica e a aplicação das novas tecnologias ao arquivo dará origem a novas formas de Trial Master Files. Para tal é importante uma análise das vantagens e desvantagens do arquivo físico, em papel, versus as mais recentes tecnologias, atualmente, presentes no mercado. A escala, a complexidade e o custo dos ensaios clínicos está a aumentar e a evolução da tecnologia a que hoje assistimos, acompanhado da gestão da documentação do ensaio clínico oferecem novas oportunidades para aumentar a eficiência e reduzir o custo.Um ensaio clínico, para além de contribuir para a inovação da medicina e da ciência, continua a ser uma atividade empreendedora com necessidade de ir acompanhando o crescimento e a modernização que acontece em seu redor.
Clinical Trials are a key part of the development of a new drug, connecting scientific and clinical research and, later, the market. The clinical part of the trial has a restricted duration, giving place to the documents in the file, to "tell the history of the trial". These documents support the submission to the authorities for the introduction of the test product on the market; and are available at the time of inspection by the competent authorities. With this dissertation we intend to review the archive of clinical trials. The collection of data on paper or electronically and the application of new technologies to the archive, which will originate new forms of Trial Master Files. For this, it is important to analyze the advantages and disadvantages of the physical archive, in paper, versus the most recent technologies currently present in the market. The scale, complexity, and cost of clinical trials are increasing, and the evolution of the technology we see today, coupled with the management of clinical trial documentation, offers new opportunities to increase efficiency and reduce costs. A clinical trial, in addition to contributing to the innovation of medicine and science, remains an entrepreneurial activity with the need to keep up with the growth and modernization that takes place around it.
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Lopes, Manuel Joaquim Cangostas Teixeira. "Avaliação financeira com opções reais." Master's thesis, 2012. http://hdl.handle.net/11328/419.
Full textAbstract:
Grande parte das pequenas e médias empresas, quando decidem fazer um investimento
raramente recorrem a um plano de negócios com todas as suas vertentes, tal como é feito nas grandes organizações. Esses investimentos são realizados com base na intuição do Gestor ou decisor, por “benchmarking”, ou por pressão dos clientes sobre a área produtiva devido a um
aumento da procura.
Acontece por vezes, que um determinado investimento tem por objectivo o aumento da
capacidade produtiva por eliminação de um dado gargalo na produção, e todos os cálculos de retorno esperado do investimento são realizados com base nesse aumento de produção. No entanto, mais tarde verifica-se que essa análise não foi correcta, pois ao remover um gargalo criou-se outro noutra zona da produção. Esta incapacidade de determinar e calcular as restrições
de produção a nível da análise financeira de investimento pode provocar graves problemas à
gestão de uma organização e até à sua sobrevivência.
Na grande parte das organizações, quando se faz análise financeira de investimentos, este
é feito pelo método convencional ou standard do Valor Actual Liquido (VAL) e da Taxa Interna de rentabilidade (TIR), não levando em consideração restrições de produção, volatilidade da procura e/ou dos preços, e muito menos é utilizada a flexibilidade das decisões ou construção de cenários, o que origina erros irreparáveis e por vezes fatais.
Esta tese tem como objectivo demonstrar a utilidade da análise financeira com opções
reais e restrição da capacidade produtiva através de um estudo de caso na empresa CEF, Sa.
Pretende-se também demonstrar a necessidade e importância de criação de modelos matemáticos e computacionais que sejam fáceis de utilizar, de forma a serem ferramentas que permitam ao Gestor tomar decisões, não somente baseadas na sua intuição, mas também sustentadas por
métodos científicas que admitem que os mercados são voláteis e onde se possa introduzir flexibilidade de decisões.
Most small and medium-sized enterprises when they decide to make an investment rarely resort to a business plan with all its aspects, as is done in large organizations. These investments are made based on the intuition of the manager or decision maker, by "benchmarking", or by customer pressure on the productive area due to an increase in demand.
It sometimes happens that a particular investment is intended to increase production capacity by
removal of a given production bottleneck, and all calculations of expected return on investment are made based on this increase of production. However, later it turns out that this analysis was not correct, because when you remove a bottleneck, another can be created in other areas of production. This inability to determine and calculate production constraints at the level of
financial analysis of investment can cause serious problems to the management of an
organization and to its survival.
In most organizations, when financial analysis of investments are made, this is done by conventional method or standard net present value (NPV) and Internal Rate of return (IRR), not taking into account restrictions on production, demand and/or price volatility, and much less use
the flexibility in decision making or construction of scenarios, leading to irreparable and sometimes fatal, errors.
This thesis aims to demonstrate the usefulness of financial analysis that contemplates real options and the restriction of production capacity, using the case study in the company CEF, Sa.
It is also intended to demonstrate the need and importance of mathematical and computer
models that are easy to use, as tools that allow the manager to make decisions not only based on intuition, but also supported by scientific methods that assume markets are volatile and where you can introduce flexibility decisions.Orientação: Prof.º Doutor Rui Neves dos Santos.
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Santos, Susana Fernandes. "O risco na análise de investimentos." Master's thesis, 2012. http://hdl.handle.net/11328/422.
Full textAbstract:
Resumo: A análise de investimento é uma das grandes preocupações dos empresários e
fulcral no clima macroeconómico que se vive sendo que a sua assertividade/exatidão vai
ser preponderante para o sucesso de qualquer investimento empresarial.
Neste momento pretendemos analisar os riscos existentes num investimento, que por
serem acrescidos, para muitas empresas podem levar ao seu incumprimento.
O objetivo deste trabalho é mostrar de que forma se podem minimizar os riscos
dos projetos, uma vez que estes são constantes como a inflação, mas que muitas vezes não são considerados.
Para além de todos os riscos inerentes como o risco inflacionário, financeiro e
conjuntural existentes, devemos também salientar que numa análise de um projeto de
investimento será necessário identificar, com maior rigor os objetivos do projeto e todos os fatores chave para a prossecução de um investimento bem-sucedido. Assim, além da
identificação do investimento propriamente dito, é vital, uma análise do mercado e uma
análise económico-financeira que sustente a ideia que se pretende desenvolver.
Na parte empírica do trabalho será realizado uma análise de risco incluindo
critérios de decisão em investimentos e várias medidas do risco baseadas no conceito de valor esperado, ou seja uma análise de viabilidade do projeto.
Abstract: The investment analysis is one of the greatest businessmen’s worries and
central in the macroeconomical environment that we live in being its
assertiveness/accuracy preponderant for any business investment success.
At this moment we mean to analyze the risks existing in an investment, that by
being increased, for many companies it can take to its failure.
The objective of this work is to show in which way the project risks can be minimized, since these are constant with the inflation, but that many times are not
considered.
Beyond all the risks involved as the inflationary risk, finance and conjectural existent, we should also point out that in an investment project analyzes will be necessary to identify, with great precision the project objectives and all the key factors to the prosecution of successful investment. Therefore, besides the identification of the
investment itself, it is vital, a market analysis and an economical-finance analysis that sustain the idea to be developed.
In the empirical part of the work will be realized a risk analysis including
decision criteria in investment and several measures of the risk based in concept of expected value, in other words an analysis of the project feasibility.Orientação: Prof.º Doutor Fernando António de Oliveira Tavares.
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Pružinová, Kateřina. "Trávení krve u flebotomů a jeho vliv na vývoj leishmanií." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-310828.
Full textAbstract:
Leishmania development in their vectors is closely connected with bloodmeal digestion. This thesis focuses on factors affecting bloodmeal digestion, egg development and Leishmania infection within the sand fly gut. First, we compared the effect of mammalian (rabbit) and avian (chicken) blood on digestion and eggs development in Phlebotomus duboscqi. Sand flies fed on chickens had twice lower protein concentrations in the midgut and significantly lower trypsin activity compared to those fed on rabbits. The highest differences in the trypsin activity were observed during first 24 hours post bloodmeal. In addition, females fed on chickens had slower eggs development and their eggs were 10 % smaller compared to those fed on rabbits. In the second part of the thesis we tested the effect of mosquito hormone TMOF on the trypsin activity and eggs development of Lutzomyia longipalpis. Rabbit blood with TMOF (28 mg/ml) was presented to the females via a membrane feeding system. Sand flies fed on blood with TMOF had 15 - 35 % less trypsin activity than control females fed on only rabbit blood. In addition, females fed on blood with TMOF had developed 30 % less eggs and their eggs were 12 - 24 % smaller compared to control group. However the effect of TMOF we observed was lower than that described previously...
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Pinho, Maria Inês Ribeiro Basílio de. "Festivais de teatro: sua gestão, impactos e financiamento." Master's thesis, 2007. http://hdl.handle.net/11328/440.
Full textAbstract:
A dissertação sobre "Festivais de teatro: sua gestão, impactos e financiamento" resulta de uma investigação iniciada em Abril de 2002, com a observação da
proliferação, na década de 90, dos festivais em Portugal. Dentro destes assistia-se a um crescimento superior em modalidades artístico-culturais como a música e
menor em teatro.
Para além disto, constatou-se que as políticas municipais e da administração central para a cultura, recorriam, com alguma regularidade, à modalidade festival como
forma de permitir que aquele bem se torne acessível a todos (bem público ou quase público).
De igual modo, verificou-se que os procedimentos administrativos utilizados para a criação e manutenção de evento eram muitos semelhantes àqueles seguidos em
estruturas empresarias, evocando-se vulgarmente o argumento da insuficiência de financiamento público com justificação do menor sucesso ou da irregularidade
das respectivas edições dos festivais.
Esta situação, quando comparada com a realidade internacional, destaca algumas diferenças de forma quanto aos modelos organizacionais seguidos, bem como
quanto às modalidades de financiamento seguidas.
A constatação destes factos conduziu, portanto, à necessidade e realização de um estudo onde se procurasse perceber se na origem destes factores estariam
aspectos como:
b) A noção, modalidades e características da estrutura organizacional festival;
c) A validade da estrutura festival e, em particular os festivais de teatro, adaptarem conceitos de organizações e gestão de empresas;
d) A capacidade de os artistas se saberem organizar, bem como pré-programar, planear, implementar e controlar festivais de teatro;
e) A comparação entre as formas de administração e financiamento empresariais e as formas de administração e financiamento de um festival de teatro.
Do confronto, entre casos nacionais e internacionais com o estudo comparativo das suas modalidades de organização e financiamento, pretendeu-se avaliar se o
conceito de "festival" se trata de um novo modelo organizacional e se as razoes explicativas da sua proliferação residem em aspectos financeiros ou igualmente em
aspectos organizativos.Orientação: prof.º Doutor Joaquim José Peres Escaleira.
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Domingos, Ayondela Josefina Eduardo. "O impacto da economia informal em Angola." Master's thesis, 2012. http://hdl.handle.net/11328/425.
Full text
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Marques, André Luís Martins. "A internacionalização no setor da cortiça: estudo exploratório às empresas." Master's thesis, 2012. http://hdl.handle.net/11328/439.
Full textAbstract:
No âmbito do Mestrado em Finanças foi desenvolvido um estudo exploratório com vista a estudar o processo de internacionalização das empresas do setor corticeiro, composto maioritariamente por micro e pequenas empresas localizadas no concelho de Santa Maria da Feira.
Na era atual de globalização dos mercados, na qual a concorrência é cada vez maior,
torna-se imperativo que as empresas procurem penetrar em novos mercados e desta
forma sobrevivam às conjunturas económicas e situações adversas com que se deparam.
No atual contexto económico a internacionalização surge como fator essencial para o aumento de competitividade das empresas.
Neste sentido este trabalho procura analisar e tentar compreender a internacionalização
do setor corticeiro, no concelho que agrega mais empresas e produtos de cortiça. Assim
contribui para identificar as perspetivas de evolução deste setor, perspetivas das
empresas, as vantagens competitivas a nível internacional, pontos fortes, pontos fracos,
oportunidades, ameaças que possui para ser líder mundial neste setor. Esta dissertação está organizada em quatro capítulos, reservados ao estudo da
internacionalização, da cortiça, metodologia usada para realização dos inquéritos, bem
como a sua análise estatística descritiva, fatorial e discussão dos resultados obtidos a partir dos mesmos. Desta investigação podemos concluir que apesar de algumas empresas estarem fortemente implantadas no mercado internacional, a maior parte dedica-se quase exclusivamente à produção com forte orientação para a qualidade.
As part of the Masters in Finance an exploratory study was developed in order to study the process of internationalization of the cork sector, consisting mainly of micro and small businesses located in the municipality of Santa Maria da Feira.
In the present era of globalization of markets, where competition is increasing, it is imperative that companies seek to penetrate new markets and thus survive the economic conditions and adverse conditions encountered. In the current economic context, internationalization emerges as key factor for increasing the competitiveness of
enterprises.
In this sense this work seeks to analyze and try to understand the internationalization of the cork industry, in the county that includes more companies and cork products. It thus contributes to identify the prospects of development of this sector, prospects of companies, the competitive advantages internationally, strengths, weaknesses, opportunities and threats it has to be world leader in this sector.
This dissertation is organized into four chapters, dealing with the study of
internationalization, cork, methodology for carrying out the surveys, as well as their
descriptive statistics, factor analysis and discussion of the results obtained from them. In this research we can conclude that although some companies are heavily deployed in international markets, most of them are almost exclusively dedicated to the production with a strong orientation towards quality.Orientação: Prof.º Doutor Fernando António de Oliveira Tavares.
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Santos, Susana Catarina Marcelino Teixeira. "Incidência da tributação de rendimentos de pessoas colectivas não residentes em Portugal: caso prático: Portugal versus Espanha." Master's thesis, 2011. http://hdl.handle.net/11328/436.
Full textAbstract:
A competitividade fiscal é um dos factores chave na atracção do investimento
estrangeiro, que para Portugal é tido como o ‘calcanhar de Aquiles’.
Para além da complexidade e dispersão dos normativos fiscais portugueses, há
o conflito com os normativos comunitários e as normas fiscais de Espanha,
nosso concorrente directo.
Os conflitos latentes a nível comunitário podem ser compreendidos via análise
da realidade espanhola. Ao compararmos a tributação que incide sobre os
rendimentos auferidos por certas entidades estrangeiras em Portugal e
Espanha, conclui-se que há notórias diferenças para pior. A taxa de tributação
efectiva é para entidades com estabelecimento estável de 29,88% contra
22,45% e para entidades sem estabelecimento estável de 22,12% contra
18,14%. A realidade além fronteiras coaduna-se mais com a menor carga fiscal
sobre entidades não residentes, a minimização dos pagamentos por conta e a
simplificação das declarações fiscais.
Porém mesmo que haja em Portugal uma menor carga fiscal, fruto dos
benefícios à interioridade, a taxa de tributação efectiva é de 19,18% contra
22,45%, toda a outra realidade mantêm-se, daí que esse não será um factor
bastante.Tax competitiveness is one of the key factors in attracting foreign investment, to Portugal this factor is reputed to be the ‘big thing’. In addition to regulatory complexity and dispersion of the Portuguese tax, there is the conflict with the Community regulatory and spanish fiscal standards, our direct competitor. Latent conflicts at Community level can be understood by analysis of Spanish reality. Comparing the taxation on income earned by certain foreign entities in Portugal and Spain, it is concluded that there are significant differences to worst. The effective tax rate is for entities with permanent establishment of 29.88% against 22.45% and for entities without permanent establishment of 22.12% against 18.14%. The reality beyond borders fits more with the lowest tax burden on non-residents, the minimization of payments on account and simplification of tax returns. But even if there is in Portugal a smaller tax burden, due to the benefits for interiority, the effective tax rate is 19.18% against 22.45%, all other reality remain, so this won't be a factor.
Orientação: Prof.º Doutor Luís Pavcheco e co-orientação da Mestre Antonieta Sousa Lima.
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Maciel, André Bernardo Silva. "Análise do desempenho económico-financeiro do Real Hospital Veterinário." Master's thesis, 2012. http://hdl.handle.net/11328/424.
Full textAbstract:
No âmbito do Mestrado em Finanças, foi realizado um estágio curricular em
contexto de trabalho na empresa Real Hospital Veterinário. Este relatório de estágio é o
resultado final desse estágio curricular. Ele orientou-se pela premissa que constituiu o objetivo primordial desde a primeira fase do trabalho: Analisar o desempenho económico e financeiro da empresa. Procurou-se com esta análise encontrar a direção mais adequada no âmbito da melhor estratégia a adotar quanto ao seu percurso.
Contudo, foi efetuada uma revisão da literatura, adaptando a forma de análise à empresa em causa. Por fim, aplicou-se a análise de acordo com o modelo da empresa, servindo-se assim de base para outras realizações.
With the aim of concluding the Master in Finance, it was done curricular internship with work-related training at Real Hospital Veterinário Lda. This report is the final outcome of this curricular internship. Its key line follows the main purpose since
the beginning of this work: analyse the economic and financial performance in the firm path. Furthermor, it was done a bibliographic review with purpose of adjust the study to the company. To conclude, it was operated that examination in accordance with corporation’s model in a way that it serves as a foundation to other researches.Orientação: Prof.º Doutor Fernando António de Oliveira Tavares.
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Valente, Manuel Henrique de Sá Couto Costa. "A harmonização versus cooperação da tributação indirecta na UE: o caso dos combustíveis rodoviários." Master's thesis, 2011. http://hdl.handle.net/11328/423.
Full textAbstract:
A problemática da harmonização/coordenação da tributação nos combustíveis rodoviários
(gasóleo e gasolina) e do fenómeno do fuel tourism numa perspectiva integrada da União
Europeia tem sido objecto de diversos estudos levados a cabo pela Comissão Europeia.
Neste sentido, foi premente e actual examinar o peso dos impostos especiais sobre o consumo na formação do preço dos combustíveis, analisando paralelamente se os esforços da Comissão Europeia, na tentativa de harmonizar a tributação dos combustíveis foram bem sucedidos, e principalmente se a chamada Directiva da Energia de 2003 em vigor, promoveu a convergência dos impostos especiais sobre o consumo e dos preços ao consumidor.
Para o efeito o trabalho empírico realizado baseou-se na análise da convergência real através da execução de testes econométricos com dados cross-section utilizando os indicadores, convergência sigma e convergência beta – absoluta.
Os testes realizados demonstram a presença de convergência nos impostos especiais sobre o consumo e nos preços ao consumidor, no período de 2005 a 2010, na União Europeia, uma vez que os indicadores beta-absoluta e sigma são ambos menores que zero, condição
necessária para a existência de convergência real.
A investigação permite concluir que apesar de se ter encontrado convergência, a Directiva da Energia de 2003 é ineficaz, e que, ainda que o peso dos impostos especiais sobre o consumo na formação do preço dos combustíveis seja incontornável, a convergência encontrada nos preços na bomba não depende só do papel desempenhado pela tributação.
The road fuels (diesel and petrol) taxation harmonisation/coordination issue and the
phenomenon of fuel tourism in an integrated perspective of the European Union has been the aim of several studies conducted by the European Commission.
Therefore it was important to analyse the excise weight on fuel prices, and also examine if European Commission parallel efforts to harmonize the fuel taxation have been successful and finally if the so called 2003 Energy Directive in force have promoted the convergence of excise taxes and consumer prices.
This empirical work was based on the analysis of real convergence through econometric tests with cross-sectional data, using sigma and absolute-beta convergence indicators.
The tests that were made show the presence of convergence in excise taxes and consumer
prices from 2005 to 2010 in the European Union, once the beta-absolute and sigma indicators are both less than zero, which is a necessary condition for real convergence existence.
The investigation allow us to conclude that, although a convergence is found, the 2003
Energy Directive is ineffective, and that despite of the inevitable excise weight in the fuel prices formation, the convergence of prices at the pump doesn’t only depend on the role played by taxation.Orientação: Prof.ª Doutora Antonieta Lima.
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Islam, Samia. "Validate a method for the determination of Cadmium and Lead by using Stripping Chronopotentiometry (SCP) obtained by thin mercury film deposited on rotating disk electrode (TMF-RDE)." Master's thesis, 2012. http://hdl.handle.net/10400.1/10623.
Full textAbstract:
Dissertação de Mestrado, Qualidade em Análises, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2012Neste trabalho, um novo método foi desenvolvido e validado para a determinação de Cd e Pb em água da torneira, com base num eléctrodo de disco rotativo (RDE-TMF), utilizando cronopotenciometria de redissolução (SCP). A espessura do TMFE foi determinada foi (1,46 ± 0,06) x 10-3 C para um intervalo de confiança de 95%. O procedimento foi composto por: potencial de deposição - 0,78 V; tempo de deposição 90 s; corrente de redissolução 5 μA e agitação de 1500 rpm. Para ambos os metais, a linearidade obtida dentro do intervalo de concentração de (2,5 × 10-9 a 1 × 10-7 M) percentagens de recuperação de foram 111 ± 15% e 103 ± 11% foram obtidos para o cádmio e para o chumbo, respectivamente (com base nos resultados dos materiais de referência certificados). Os limites de detecção obtidos para o Cd e Pb foram de (4,7 ± 3,8) x 10-10 M e (3,2 ± 0,4) x 10-10 M, respectivamente, e foram também obtidos valores de CV < 8%. O método analítico SCP revelou-se eficaz para a determinação de cádmio e chumbo na água da torneira utilizando o filme fino de mercúrio depositado sob um eléctrodo de disco rotativo.
A new validated method for Cd and Pb determinations in tap water, based on rotating disk electrode (TMF-RDE), using stripping chronopotentiometry (SCP), was developed. The TMFE thickness determined was determined at (1.46 ± 0.06) × 10-3 C for 95% confidence interval. The procedure comprised: deposition potential - 0.78 V; deposition time 90 s; stripping current 5 μA and stirring rate 1500 rpm. For both metals linearity was achieved within the concentration range of (2.5 × 10-9 to 1 × 10-7 M) with a high value of the regression coefficient based on the results of the Certified Reference Materials the trueness values in terms of % recovery were found to be 111 ± 15 % and 103 ± 11 % for cadmium and lead respectively. Detection limits of (4.7 ± 3.8) × 10-10 M and (3.2 ± 0.4) × 10-10 M were obtained for Cd and Pb, respectively, and CV values < 8% were observed. SCP was found to be an effective method for cadmium and lead in tap water by using thin mercury film on rotating disk electrode.
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Lima, Antonieta Maria Sousa. "Estudo do comportamento da taxa de câmbio real: abordagem tradicional versus nova abordagem: caso." Master's thesis, 2005. http://hdl.handle.net/11328/441.
Full textAbstract:
O tema desta investigação é o estudo do comportamento da taxa de câmbio real, subordinado a dois
objectivos fundamentais: expor a literatura existente neste âmbito, explorando novos pressupostos e, testar
empiricamente o mercado cambial chinês.
A investigação baseia-se nos fundamentos teóricos de Gustav Cassel e em toda a problemática gerada em
torno da paridade do poder de compra, alargando-se a novas linhas de pensamento (risco de um país).
Assim, é dada especial importância aos factores determinantes da taxa de câmbio real, à interacção entre a
taxa de câmbio e o risco de um país e à série de dados adequada ao tratamento empírico da teoria.
O estudo empírico desenvolve-se para a taxa de câmbio USD/RMB, no período decorrente entre 1986 e 2005.
A metodologia recorre a testes de estacionaridade Augumented Dickey-Fuller e a testes de coientegração de
Engle Granger, às versões absoluta e relativa da paridade do poder de compra, e ao modelo da
micro-estrutura de mercado. Os resultados não apontam de forma inquestionável para a validação, ou não, da
paridade do poder de compra e do modelo de risco de um país, embora tenha surgido uma certa robustez da
teoria.Orientação: Prof.º Doutor Vasco Soares.
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Reis, Américo David Soares dos. "A importância da informação no mercado de capitais para os alunos do ensino superior." Master's thesis, 2012. http://hdl.handle.net/11328/427.
Full textAbstract:
O mercado de capitais é um mercado onde se transaciona antes de tudo informação, onde o investidor é o grande consumidor. Pretendeu-se assim com este trabalho, compreender a capacidade de investimento dos alunos do ensino superior, como estes interagem com a informação e se esta influencia o seu comportamento, recorrendo a metodologia quantitativa de inquérito por questionário, do qual se recolheram 323 alunos, o que permite realizar os testes com maior significância estatística. Obtiveram-se importantes conclusões aferindo que 40,6% dos alunos tem capacidade de investimento tendo já investido alguma vez no mercado de capitais, os produtos em que preferem investir são os certificados de aforro, fundos de investimento e ações. Atualmente 41,2% estão dispostos a fazer investimentos no curto prazo, quanto ao seu perfil de investidor 9% dos homens estão dispostos a assumir maiores riscos nos investimentos em relação a 5,6% das mulheres; 16,2% dos homens são mais confiantes na utilização da informação do que 8,9% das mulheres, como aspeto que deu origem às decisões de investir; 52,7% consideram o nível atual de informação disponível insuficiente. Concluindo assim que as variáveis que melhor definem e influenciam os alunos enquanto investidores são a classificação da informação, excesso de confiança na utilização da informação disponível, a idade e o género.
Financial Markets are the place where we trade above all information and the biggest consumer is the trader. With this research I tried to understand the ability of college students to do investments and how do they react and interact with information, understanding their behavior., using for this the questionnaire methodology. Important results were founded, showing that 40,6% of students already did investments on financial markets and finding their preference products to do investments like stocks and investments funds. Actually 41,2% of the students profile investor are available to do investments but only in short term, 9% of male students profile investor are available to assume more risk on their investments compare with 5,6% of female students, in other hand 16,2% of male students are more confident than the female students are in only 8,9% about how do they use the information and decide to invest, the available information is considered not enough on 52,7%. Is possible to conclude that exist some variables can explain the investment students behavior like overconfidence, feeling about information, region, age and gender.Orientação: Prof.º Doutor Vasco Jorge Salazar Soares.