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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Predictors of Mastectomy in Male Breast Cancer

Opara, Esther 01 January 2017 (has links)
Male breast cancer (MBC) is rare, and research on the predictors of MBC has been limited because of inadequate funding in and outside of the United States. One goal of this study was to eradicate the stereotyping of breast cancer as a female disease. The emergence of medical technology and education to benefit the public will help to ensure greater health awareness at the individual, community, and global levels. The purpose of this study was to understand the influence of the predictors of age; race (Black, White, and Other); and grade of cancer (I, II, or III) on the outcome of mastectomy in MBC. The study was guided by the social determinants of health model. A quantitative approach was used to analyze archival data from 2011 to 2013 in the Surveillance Epidemiology and End Results (SEER) database using SPSS v.23. Data from 427 MBC patients ages 18 years and older from the United States comprised the sample. The SEER data were analyzed using logistic regression analysis. Results showed that of the 427 cases of MBC that were analyzed, 55 had a diagnosis of Grade I, 190 had a diagnosis of Grade II, and 182 had a diagnosis of Grade III. For 3 years, 116 men had undergone mastectomy. Grade I cancer, Grade II cancer, and Grade III cancer were statistically insignificant predictors of mastectomy; however, age, race was a statistically significant predictor of mastectomy among White men with MBC. The results will contribute to social change initiatives by educating the public about the predictors of mastectomy in MBC patients. The results also will increase the current knowledge base by informing the public, clinical professionals, and patients about the relationship of the predictors of age; race; and grade of cancer (I, II, or III) on the outcome of mastectomy in MBC.
12

Egypt is mother of the world : transnational television and national identity

Elseewi, Tarik Ahmed 03 December 2010 (has links)
This dissertation is about the production of national identity in the transnational age. Focusing on the specific example of Egyptian television, this dissertation argues that new production imperatives, mainly in satellite television and internet, have changed the way that television is produced in the Arabic speaking Middle East, most significantly away from direct state control. The changes in production accompany changes in distribution and consumption of electronic media and are significantly rewriting the ways that shared cultural identities in the Middle East, including nationalism, religious, and other significant identities, are produced, consumed and replicated. This dissertation approaches these topics by relating two specific televisual texts, the Ramadan serials Malek Farouq and Gamal Abdel Nasser, to larger changes in Arab and Egyptian television production. / text
13

Influence of Size and Interface Effects of Silicon Nanowire and Nanosheet for Ultra-Scaled Next Generation Transistors

Orthi Sikder (9167615) 28 July 2020 (has links)
<div>In this work, we investigate the trade-off between scalability and reliability for next generation logic-transistors i.e. Gate-All-Around (GAA)-FET, Multi-Bridge-Channel (MBC)-FET. First, we analyze the electronic properties (i.e. bandgap and</div><div>quantum conductance) of ultra-thin silicon (Si) channel i.e. nano-wire and nano-sheet based on first principle simulation. In addition, we study the influence of interface</div><div>states (or dangling bonds) at Si-SiO<sub>2</sub> interface. Second, we investigate the impact of bandgap change and interface states on GAA-FETs and MBC-FETs characteristics by</div><div>employing Non-equilibrium Green's Function based device simulation. In addition to that, we calculate the activation energy of Si-H bond dissociation at Si-SiO<sub>2</sub> interface for different Si nano-wire/sheet thickness and different oxide electric-field. Utilizing these thickness dependent activation energies for corresponding oxide electric-field, in conjunction with reaction-diffusion model, we compute the characteristics shift and analyze the negative bias temperature instability in GAA-FET and MBC-FET. Based on our analysis, we estimate the operational voltage of these transistors for a life-time of 10 years and the ON current of the device at iso-OFF-current condition. For example, for channel length of 5 nm and thickness < 5 nm the safe operating voltage needs to be < 0.55V. Furthermore, our analysis suggests that the benefit of Si thickness scaling can potentially be suppressed for obtaining a desired life-time of GAA-FET and MBC-FET.</div>
14

Antimicrobial Activity of Fractionated Borohydride-Capped and Electrochemical Colloidal Silver

Markopoulos, Marjorie M. January 2017 (has links)
No description available.
15

Interferenzen endokrin aktiver Substanzen mit der Hypothalamus-Hypophysen-Schilddrüsenachse

Gotthardt, Inka 22 June 2010 (has links)
Endokrin aktive Substanzen (EACs) sind exogene Substanzen natürlichen oder synthetischen Ursprungs, die mit der Feedbackregulation hormoneller Netzwerke interferieren können und somit deren Homöostase beeinflussen. Störungen der Hypothalamus-Hypophysen-Schilddrüsenachse (HPT-Achse) haben weitreichende Konsequenzen, da Schilddrüsenhormone essentiell für die Regulation von Entwicklung, Wachstum und Stoffwechsel sind. In der vorliegenden Arbeit wurde das Wirkprofil potenter Inhibitoren der thyreotropen Achse am Beispiel von 4-Methylbenzyliden-campher (4-MBC) und Genistein (GEN) untersucht. Der UV-Filter 4-MBC wurde in der ovariektomierten Ratte als goitrogene Substanz identifiziert. 4-MBC interferiert auf Ebene von Hypothalamus und Hypophyse mit der Expression Feedback-assoziierter Gene und beeinflusst daher die Feedbackregulation der thyreotropen Achse. Darüber hinaus wird die Biosynthese von Schilddrüsenhormonen durch Inhibition des Iodidtransports bei gleichzeitig erhöhter messenger RNA (mRNA)-Konzentration des Natrium-Iodid-Symporters (NIS) durch 4-MBC beeinträchtigt. Parallel dazu lässt die verstärkte Expression des Angiogenesemarkers vascular endothelial growth factor (VEGF) nach subakuter Exposition auf die Entstehung einer Hypothyreose schließen. Die damit einhergehenden Veränderungen sind auch in peripheren Organen durch die Analyse 3,3‘,5-Triiod-L-thyronin (T3)-regulierter Zielgene dokumentiert. Zudem wurden diese Effekte maßgeblich durch die Expositionszeit beeinflusst, da nach chronischer Exposition vermutlich auch kompensatorische Prozesse eine wichtige Rolle spielen. Die gezeigten speziesspezifischen Effekte lassen sich möglicherweise auf Unterschiede in der Pharmakokinetik zurückführen, z.B. in Folge differentieller Expression von Cytochrom P450-Genen. / Endocrine active compounds (EACs) can be of natural or synthetic origin and show hormone-like effects that interfere with feedback regulation of hormonal networks. Interferences with the hypothalamic-pituitary-thyroid axis (HPT-axis) result in extensive consequences as thyroid hormones are essential for regulation of development, growth, and metabolism. In the work presented here, the active profile of potent inhibitors of the HPT-axis namely 4-methylbenzylidene-camphor (4-MBC) and genistein (GEN) was investigated. 4-MBC, a UV filter used in sunscreens and various cosmetics, was identified as a goiter causing agent using ovariectomized rats. 4-MBC acts at the level of hypothalamus and pituitary gland by modulating the expression of thyrotropin-releasing hormone (TRH) as well as thyroid-stimulating hormone (TSH) that regulate feedback on the HPT-axis. Furthermore, biosynthesis of thyroid hormones was impaired by 4-MBC secondary to the inhibition of iodide transport with concomitantly increased messenger RNA (mRNA)-levels of the sodium-iodide symporter (NIS). In parallel expression of the angiogenesis marker vascular endothelial growth factor (VEGF) was increased, indicating hypothyroidism. After the application of 4-MBC the expression of L-3,3’,5-triiodothyronine (T3)-regulated target genes was reduced in the periphery both on the mRNA and protein level. The documented species-specific effects indicate a difference in pharmacokinetics, possibly secondary to differential expression of cytochrome P450 genes. GEN is contained in soy and red clover and its mechanistic analysis was carried out in thyroid hormone receptor (TR) deficient mice (TRα0/0). The gender-dependent effects of GEN on tissue specificity did not follow an obvious pattern and warrant continuative analysis. The work presented here supports the assumption that EACs can interfere with function and regulation of the HPT-axis at levels that were previously considered safe.
16

韓國公共電視工會運動發展-以2012年MBC罷工為例 / The Development of Korea Public TV Union Movement: The Case Study of MBC Strike in 2012

田育志, Tian, Yu Jhih Unknown Date (has links)
韓國公共電視之一的MBC,因新聞報導立場不公、社長金在哲利用人事權力不當解雇批判執政黨的製作人與記者,造成MBC喪失公正放送的意義,員工為捍衛公共電視的價值,在工會的帶領下,於2012年1月底展開長達170天的罷工。為了解這場罷工的前因後果,以及對台韓媒體工會運動帶來的意義,本研究透過深度訪談與次級資料分析,檢視2012年MBC罷工的事前、事中與事後經過。   研究發現,導致MBC工會發起罷工的事前原因,來自於MBC政治朋黨化下親執政黨立場的管理階層,與李明博政府欲將MBC私有化而影響MBC節目內容走向的舉動,破壞了MBC身為公共電視應保有的「公正放送」價值。而罷工當時,MBC工會成員的高度參與,社會大眾與其他媒體工會的聲援,促使這場罷工得以延續長達170天。可惜的是,罷工結束後,MBC不僅無力保障公正放送,阻止MBC的政治朋黨化與私有化,更造成勞資間原有的團體協約中斷;MBC工會認為,短期之內可藉由社長選任制度的改革著手,而長期則要仰賴執政者對公共電視獨立地位的認可,才有希望達到公正放送的目標。   另外,這場為捍衛「公正放送」而展開的罷工行動,也可發現除了薪資與福利之外,媒體工作者的「專業價值」也是工會在意的勞動條件;這就是本研究在分析2012年MBC罷工後,所觀察到工會在「民主性功能」的展現。同時,民主性功能也是未來台灣學術研究上,可以用以分析媒體工會的另一觀點。 / As one of the public TV networks in Korea, MBC has lost the impartiality of broadcasting for its biased news reports and the unfair dismissal by the MBC’s president, Kim Jae-Chul, of producers and journalists who criticized the government. For protecting the value as a public TV, MBC employees ,led by the MBC union, started a 170-day strike in January, 2012. In order to realize the causes and effects of this strike, and the implications for the media union movement both in Taiwan and Korea, this study will examine the causes, the processes and the effects of the strike by using in-depth interview and secondary data analysis. According to the research data, the causes of the strike were due to political factions of MBC’s executive management and the ruling party, and the privatization of the MBC by Lee Myeong-Bak Administration; those two causes destroyed the impartiality of broadcasting, which was the central value that the public TV was supposed to protect. The strike had continued for 170 days with a high degree of participation from the MBC union and the supports from other media unions and the citizens. Unfortunately, after the strike, MBC was still neither able to protect the impartiality of broadcasting nor to maintain the organizational contract between the union and the management. Talking about the protecting of the impartiality of broadcasting, the MBC union considered that it could be a short-term target to reform the election system of president in MBC, but in the long-term, it needs the ruler to take the public TV as an independent media. Besides, through the strike which was started by protecting “the impartiality of broadcasting”, we can find out that not only the wage and welfare, but the professional values of media workers is the working condition that a union will be concerned about. And it’s so-called “the function of democracy” of the union which is a research finding by analyzing the MBC strike in 2012. Furthermore, the academic circle in Taiwan can also take the function of democracy as another viewpoint to analyze the media union.
17

Effets des fluorures sur l'activité antimicrobienne des antibiotiques contre Staphylococcus aureus et Pseudomonas aeruginosa

Riazi, Mansour 12 1900 (has links)
L’émergence des souches bactériennes résistantes aux antibiotiques est un phénomène inquiétant, qui se répand à travers le monde. Staphylococcus aureus et Pseudomonas aeruginosa sont des bactéries pathogènes opportunistes multi résistantes qui peuvent causer plusieurs maladies. Cependant, ces bactéries deviennent difficiles à traiter avec des antibiotiques sans occasionner de toxicité. Alors pour trouver des solutions, c’est nécessaire de développer de nouvelles molécules afin de combattre les agents pathogènes résistants. Grâce à leur action pharmacologique, les fluorures exercent un certain effet antibactérien au niveau de l'émail des dents; donc, leur association aux antibiotiques pourrait bien a méliorer l’activité antimicrobienne. De ce fait, nous nous sommes proposés d’étudier les activités in vitro de la vancomycine (VAN), l’oxacilline (OXA), la ceftazidime (CFT) et la méropenème (MER) libre ou associée au fluorure de sodium (NaF) et fluorure de lithium (LiF) qui ont été évaluées sur des souches S.aureus et P.aeruginosa sensibles et résistantes, par la méthode de la microdilution en bouillon, déterminant leur concentration minimale inhibitrice (CMI), leur concentration minimale bactéricide (CMB), leur courbe cinétique (Time-Kill). Leur cytotoxicité sur les globules rouges humains, et leur stabilité à la température de 4°C et 22°C ont été étudiées. Les associations des antimicrobiens aux dérivés des fluorures ont montré une amélioration de l’effet des antibiotiques par la réduction des leurs concentrations et toxicité pour traiter correctement ces pathogènes résistants. Par conséquent, des antibiotiques associés aux dérivés de fluorure pourraient devenir une option de traitement contre des souches résistantes afin de diminuer la toxicité causée par de fortes doses des antibiotiques conventionnels. / The emergence of bacterial strains resistant to antibiotics is a worrying phenomenon, which has spread worldwide. Staphylococcus aureus and Pseudomonas aeruginosa are multi-resistant opportunistic pathogenic bacteria that can cause many diseases. However, they have become difficult to treat with antibiotics without causing toxicity to humans. It is therefore necessary to develop new molecules against resistant pathogens to combat this problem. Due to their pharmacological action, fluorides have an antibacterial effect on tooth enamel which suggests that their combination with antibiotics could improve antimicrobial activity. Thus, we proposed to study in vitro activities of vancomycin (VAN), oxacillin (OXA), ceftazidime (CFT) and meropenem (MER) alone or combined with sodium fluoride (NaF) and lithium fluoride (LiF ) that were evaluated against resistant and susceptible strains of S. aureus and P. aeruginosa by antimicrobial susceptibility testing , in determining their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and kinetics (Time-Kill). The evaluation of cytotoxicity on human red blood cells, and determination of stability at two different temperatures (4°C, 22°C) were also performed. Associations of antibiotics with fluoride derivatives showed an improvement by increasing the effect of antibiotics with minimal levels necessary to achieve the same result by reducing their toxicity and to properly kill these resistant pathogens. Therefore, antibiotics associated with fluoride derivatives could become a treatment option against resistant strains and at the same time reduce the toxicity caused by high doses of conventional antibiotics.
18

Effets des fluorures sur l'activité antimicrobienne des antibiotiques contre Staphylococcus aureus et Pseudomonas aeruginosa

Riazi, Mansour 12 1900 (has links)
L’émergence des souches bactériennes résistantes aux antibiotiques est un phénomène inquiétant, qui se répand à travers le monde. Staphylococcus aureus et Pseudomonas aeruginosa sont des bactéries pathogènes opportunistes multi résistantes qui peuvent causer plusieurs maladies. Cependant, ces bactéries deviennent difficiles à traiter avec des antibiotiques sans occasionner de toxicité. Alors pour trouver des solutions, c’est nécessaire de développer de nouvelles molécules afin de combattre les agents pathogènes résistants. Grâce à leur action pharmacologique, les fluorures exercent un certain effet antibactérien au niveau de l'émail des dents; donc, leur association aux antibiotiques pourrait bien a méliorer l’activité antimicrobienne. De ce fait, nous nous sommes proposés d’étudier les activités in vitro de la vancomycine (VAN), l’oxacilline (OXA), la ceftazidime (CFT) et la méropenème (MER) libre ou associée au fluorure de sodium (NaF) et fluorure de lithium (LiF) qui ont été évaluées sur des souches S.aureus et P.aeruginosa sensibles et résistantes, par la méthode de la microdilution en bouillon, déterminant leur concentration minimale inhibitrice (CMI), leur concentration minimale bactéricide (CMB), leur courbe cinétique (Time-Kill). Leur cytotoxicité sur les globules rouges humains, et leur stabilité à la température de 4°C et 22°C ont été étudiées. Les associations des antimicrobiens aux dérivés des fluorures ont montré une amélioration de l’effet des antibiotiques par la réduction des leurs concentrations et toxicité pour traiter correctement ces pathogènes résistants. Par conséquent, des antibiotiques associés aux dérivés de fluorure pourraient devenir une option de traitement contre des souches résistantes afin de diminuer la toxicité causée par de fortes doses des antibiotiques conventionnels. / The emergence of bacterial strains resistant to antibiotics is a worrying phenomenon, which has spread worldwide. Staphylococcus aureus and Pseudomonas aeruginosa are multi-resistant opportunistic pathogenic bacteria that can cause many diseases. However, they have become difficult to treat with antibiotics without causing toxicity to humans. It is therefore necessary to develop new molecules against resistant pathogens to combat this problem. Due to their pharmacological action, fluorides have an antibacterial effect on tooth enamel which suggests that their combination with antibiotics could improve antimicrobial activity. Thus, we proposed to study in vitro activities of vancomycin (VAN), oxacillin (OXA), ceftazidime (CFT) and meropenem (MER) alone or combined with sodium fluoride (NaF) and lithium fluoride (LiF ) that were evaluated against resistant and susceptible strains of S. aureus and P. aeruginosa by antimicrobial susceptibility testing , in determining their minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and kinetics (Time-Kill). The evaluation of cytotoxicity on human red blood cells, and determination of stability at two different temperatures (4°C, 22°C) were also performed. Associations of antibiotics with fluoride derivatives showed an improvement by increasing the effect of antibiotics with minimal levels necessary to achieve the same result by reducing their toxicity and to properly kill these resistant pathogens. Therefore, antibiotics associated with fluoride derivatives could become a treatment option against resistant strains and at the same time reduce the toxicity caused by high doses of conventional antibiotics.
19

Epidemiological aspects of MBC resistance in Monilinia fructicola (Wint.) Honey and mechanisms of resistance

Sanoamuang, Niwat January 1992 (has links)
Isolates of Monilinia fructicola (Wint.) Honey obtained from stone fruit orchards in Hawkes Bay, North Island and from Californian fruit exported to New Zealand, were tested for resistance to methyl benzimidazole carbamate (MBC). Resistant isolates from the North Island had EC₅₀ values of >30,000, and most isolates from the imported fruit had of values approximately 1.5 mg a.i./l carbendazim. Sensitive isolates failed to grow on 1 mg a.i./l carbendazim. A detached peach shoot system was used in controlled conditions for estimation of values for incubation period, latent period and rate of spore production on flowers (cv Glohaven). The same variables and the rate of colonisation of host tissue were measured on fruit (cv Fantasia) in controlled conditions. An inoculum density of 1x10⁴ spore/flower or fruit greatly increased fitness in vivo compared to an inoculum density of 1x10² spore/flower (fruit). Isolates varied considerably, but there was no consistent relationship between the degrees of resistance and fitness. This was in contrast to earlier studies with dicarboximide resistant strains of M. fructicola. The survival in the field of 10 isolates resistant or sensitive to MBC or dicarboximide fungicides on twig cankers and mummified fruit was compared. The ability to produce conidia on twig cankers inoculated in late spring 1989 was maintained by all sensitive and MBC resistant isolates for at least 1 year. The production of conidia on mummified fruit inoculated in February 1990 decreased after 2-3 months in the field but some conidia were still produced on all fruit in the following spring. Dicarboximide resistant isolates produced less conidia than either the MBC resistant and the sensitive isolates. The pathogenicity and fitness of all isolates were similar to the original values after survival for 1 year. A technique was developed to produce apothecia reliably from inoculated peach (cv Black Boy) and nectarine (cv Fantasia) fruit in controlled conditions in the laboratory. The fruit were inoculated with resistant or sensitive isolates, or combinations, and were incubated for 8 weeks at 25°C (±1°C) with 12 hours photoperiod of fluorescent light (Sylvania 2x65 W, daylight) to produce mummified fruit. The fruit were then buried in moist autoclaved peat moss for 10 weeks at 25°C (±1°C) in the dark to form stromata. These fruit were then hydrated with running tap-water (total hardness (CaCO₃) = 47 g/m³ and conductivity at 20°C = 12.7 mS/m) for 72 hours. The hydrated mummified fruit were placed in moist peat moss and were incubated for 13-14 weeks at 8°C (±0.5°C) in the dark. At the end of this period, stipe initials were visible. Differentiation of stipe initials into mature apothecia occurred within 15-20 days after transfer to 12°C (±2 °C) with a 12 hour photoperiod of fluorescent and incandescent light. All isolates produced apothecia when treated in this way. A technique for isolation of ascospore sets in linear arrangement was developed for tetrad analysis of the inheritance of resistance. At least 3 hours of fluorescent and incandescent light at 12°C (±2°C) was essential to allow ascospore ejection from individual asci taken from apothecia previously maintained in a 12 hour photoperiod at 12°C (±1°C). A water film on the surface of water agar was necessary to hold a set of ejected ascospores in linear sequence. Single ascospores were obtained in sequence with the aid of a micromanipulator. Genetic analysis of MBC resistant isolates was carried out on ascospores derived from apothecia produced in the laboratory. Analysis of ascospore sets in linear arrangement and ascospore populations indicated that resistance to >30,000 mg a.i./l carbendazim (high-resistant) is governed by a single major gene and is affected by gene conversion mechanisms. Crossing over was frequent, suggesting that recombination of resistance with other characters, such as pathogenicity and fitness, may occur readily. The segregation ratio (1:1) from most resistant isolates revealed that heterokaryons containing both resistant and sensitive alleles were common in resistant populations and that resistance is dominant. Allozyme analysis of ascospore progeny through electrophoresis revealed a narrow genetic base of M. fructicola in New Zealand. The technique for reliable apothecial production in controlled conditions developed in this study provided an important step for the determination of the biology of M. fructicola strains resistant to MBC fungicides, and the complexity of its life cycle. Genetic heterogeneity in field populations can be conserved in one isolate through heterokaryosis, thus providing for adaptability of the pathogen to the changing environmental conditions. Knowledge on genetic variability, overwintering ability, pathogenicity and fitness factors may be useful for future management strategies of stone fruit brown rot. Special emphasis should be made in particular to prevent primary infection on blossoms, which would delay the establishment of recombinant strains of M. fructicola and the onset of brown rot epidemics.
20

Assessment of fuel consumption reduction strategies on a gasoline turbocharged direct injection engine with a cooled EGR system

Rivas Perea, Manuel Eduardo 01 September 2016 (has links)
[EN] This research work presents the study of a low pressure EGR loop influence on a SI gasoline turbocharged direct injection engine in steady and transient testing conditions, with an optimization process of the original engine calibration in order to minimize the engine fuel consumption when cooled EGR is introduced in steady testing conditions. The cooled EGR strategy was also evaluated operating in synergy with other fuel consumption reduction strategies, such as: lean burn, multi-injection, higher coolant temperature and in-cylinder induced swirl motion. To fulfill the main objectives of this research work, firstly, a methodical process was followed, where a global methodology was first developed in order to obtain high accuracy engine tests, based on the experimental tools chosen that could comply with the requirements of the testing conditions, and the appropriate theoretical tools and procedure to post-process the tests performed. Secondly, a specific methodology was developed for each stage of the study and testing conditions, taking into account optimization processes or parametric tests in order to study the effect of a single parameter on engine's outputs or optimize an engine parameter in order to minimize the engine fuel consumption. As a first stage of the study, a basic analysis of the impact of cooled EGR on the engine combustion, performance, air management and exhaust emissions is presented. Afterwards, an optimization of the combustion phasing in order to minimize the fuel consumption was performed, and therefore the potential of cooled EGR in order to reduce the engine fuel consumption was observed for low load, part load and full load engine conditions, for two different engine speeds. In addition, a study in transient conditions of the engine operating with cooled EGR was performed. NEDC cycles were performed with different EGR valve openings and therefore a comparison of different cooled EGR rates influence on the engine performance, air management and accumulated exhaust emissions was presented. The second stage, consisted in a methodology developed to optimize the VVT setting and injection timing, for part load engine conditions, in order to maximize the cooled EGR potential to reduce engine fuel consumption. After this optimization, a synergy analysis of the optimum engine condition operating with cooled EGR and three other engine fuel consumption reduction strategies was performed. These strategies were tested to investigate and evaluate the potential of increasing the cooled EGR operational range to further decrease the engine fuel consumption. Furthermore, a basic study of the potential to reduce the engine fuel consumption and impact on combustion, air management and exhaust emissions of a lean burn strategy, in part load engine conditions, was presented as introduction of the final study of the cooled EGR strategy operating in synergy with the lean burn strategy in order to investigate the potential to control the exhaust emissions and reduce the engine fuel consumption. / [ES] El objetivo de este trabajo de investigación es estudiar la influencia de un lazo de baja presión de EGR en las prestaciones de un motor de gasolina de encendido provocado turbosobrealimentado e inyección directa, en condiciones de ensayos estacionarios y transitorios, con un proceso de optimización de la calibración original del motor para minimizar el consumo de combustible del motor. La estrategia de "cooled EGR" fue también evaluada operando en sinergia con otras estrategias usadas para reducir el consumo de combustible del motor, entre ellas: mezcla pobre, múltiples inyecciones, operación a alta temperatura del fluido refrigerante del motor y movimiento de "swirl" inducido en el cilindro. Para cumplir con los objetivos mencionados, se siguió un proceso metódico donde previamente se desarrolló una metodología global para obtener resultados de indudable calidad, basados en el uso de herramientas experimentales que cumplieran con los requerimientos de las condiciones de ensayo, y las apropiadas herramientas teóricas y procedimiento para post-procesar los ensayos realizados. En segundo lugar, se desarrolló una metodología específica para cada etapa del estudio, teniendo en cuenta los procesos de optimización o estudios paramétricos que se pudieran realizar. Como primera etapa, se presenta un estudio básico del impacto del "cooled EGR" en la combustión, prestaciones, renovación de la carga y emisiones contaminantes del motor. Seguidamente, se procedió a la optimización del centrado de la combustión con la finalidad de minimizar el consumo de combustible del motor y poder analizar el potencial del "cooled EGR" como estrategia de reducción de consumo de combustible. El estudio presentado se realizó para baja, media y alta carga del motor con dos diferentes regímenes de giro del motor. Adicionalmente, se llevó a cabo un estudio del motor operando en condiciones transitorias con "cooled EGR". Se realizaron una serie de ensayos usando el ciclo NEDC como base y se probaron diferentes estrategias sencillas de control de la apertura de la válvula de EGR para analizar la influencia del "cooled EGR" en condiciones transitorias. La segunda etapa consiste en el desarrollo de una metodología para optimizar los parámetros del diagrama de distribución (VVT) y el inicio de inyección, para cargas medias del motor, con la finalidad de maximizar el potencial de reducción de consumo de combustible de la estrategia "cooled EGR". Una vez realizada la optimización, se llevó a cabo un estudio usando la configuración óptima encontrada, operando en sinergia con otras tres estrategias usadas para reducir el consumo de combustible del motor. Estas estrategias fueron evaluadas con la finalidad de incrementar el rango de operación de la estrategia "cooled EGR" para lograr reducir aún más el consumo de combustible del motor. Adicionalmente, se llevó a cabo un estudio básico sobre la influencia de operar con mezcla pobre en la combustión, prestaciones, renovación de la carga y emisiones contaminantes del motor, como introducción al último estudio llevado a cabo sobre la posibilidad de usar la estrategia de mezcla pobre en conjunto con la estrategia de "cooled EGR", con la finalidad de analizar el potencial de controlar las emisiones contaminantes y reducir el consumo de combustible del motor al mismo tiempo. / [CAT] L'objectiu d'este treball d'investigació és estudiar la influència d'un llaç de baixa pressió d'EGR en les prestacions d'un motor de gasolina d'encesa provocat turbosobrealimentat i injecció directa, en condicions d'assajos estacionaris i transitoris, amb un procés d'optimització del calibratge original del motor per a minimitzar el consum de combustible del motor. L'estratègia de "cooled EGR" va ser també avaluada operand en sinergia amb altres estratègies usades per a reduir el consum de combustible del motor, entre elles: mescla pobra, múltiples injeccions, operació a alta temperatura del fluid refrigerant del motor i moviment de `"swirl" induït en el cilindre. Per a complir amb els objectius mencionats, es va seguir un procés metòdic on prèviament es va desenrotllar una metodologia global per a obtindre resultats d'indubtable qualitat, basats en l'ús de ferramentes experimentals que compliren amb els requeriments de les condicions d'assaig, i les apropiades ferramentes teòriques i procediment per a post- processar els assajos realitzats. En segon lloc, es va desenrotllar una metodologia específica per a cada etapa de l'estudi, tenint en compte els processos d'optimització o estudis paramètrics que es pogueren realitzar. Com a primera etapa, es presenta un estudi bàsic de l'impacte del "cooled EGR" en la combustió, prestacions, renovació de la càrrega i emissions contaminants del motor. A continuació, es va procedir a l'optimització del centrat de la combustió amb la finalitat de minimitzar el consum de combustible del motor i poder analitzar el potencial del "cooled EGR" com a estratègia de reducció de consum de combustible. L'estudi presentat es va realitzar per a baixa, mitja i alta càrrega del motor amb dos diferents règims de gir del motor. Addicionalment, es va dur a terme un estudi del motor operand en condicions transitòries amb "cooled EGR". Es van realitzar una sèrie d'assajos usant el cicle NEDC com a base i es van provar diferents estratègies senzilles de control de l'obertura de la vàlvula d'EGR per a analitzar la influència del "cooled EGR" en condicions transitòries. La segona etapa consistix en el desenrotllament d'una metodologia per a optimitzar els paràmetres del diagrama de distribució (VVT) i l'inici d'injecció, per a càrregues mitges del motor, amb la finalitat de maximitzar el potencial de reducció de consum de combustible de l'estratègia "cooled EGR". Una vegada realitzada l'optimització, es va dur a terme un estudi usant la configuració òptima trobada, operant en sinergia amb altres tres estratègies usades per a reduir el consum de combustible del motor. Estes estratègies van ser avaluades amb la finalitat d'incrementar el rang d'operació de l'estratègia "cooled EGR" per a aconseguir reduir encara més el consum de combustible del motor. Addicionalment, es va dur a terme un estudi bàsic sobre la influència d'operar amb mescla pobra en la combustió, prestacions, renovació de la càrrega i emissions contaminants del motor, com a introducció a l'últim estudi dut a terme sobre la possibilitat d'usar l'estratègia de mescla pobra en conjunt amb l'estratègia de "cooled EGR", amb la finalitat d'analitzar el potencial de controlar les emissions contaminants i reduir el consum de combustible del motor al mateix temps. / Rivas Perea, ME. (2016). Assessment of fuel consumption reduction strategies on a gasoline turbocharged direct injection engine with a cooled EGR system [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68497 / TESIS

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