940 resultados para Oil. External constraint. Development


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Includes bibliographical references.

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In the last years the need to develop more environmentally friendly and efficient cars as led to the development of several technologies to improve the performance of internal combustion engines, a large part of the innovations are focused in the auxiliary systems of the engine, including, the oil pump, this is an element of great importance in the dynamics of the engine as well a considerable energy consumer. Most solutions for oil pumps to this day are fixed displacement, for medium and high speeds, the pump flow rate is higher than the needs of the engine, this excess flow leads to the need for recirculation of the fluid which represents a waste of energy. Recently, technological advances in this area have led to the creation of variable displacement oil pumps, these have become a 'must have' due to the numerous advantages they bring, although the working principle of vane or piston pumps is relatively well known, the application of this technology for the automotive industry is new and brings new challenges. The focus of this dissertation is to develop a new concept of variable displacement system for automotive oil pumps. The main objective is to obtain a concept that is totally adaptable to existing solutions on the market (engines), both dimensionally as in performance specifications, having at the same time an innovative mechanical system for obtaining variable displacement. The developed design is a vane pump with variable displacement going in line with existing commercial solutions, however, the variation of the eccentricity commonly used to provide an variable displacement delivery is not used, the variable displacement is achieved without varying the eccentricity of the system but with a variation of the length of the pumping chamber. The principle of operation of the pump is different to existing solutions while maintaining the ability to integrate standard parts such as control valves and mechanical safety valves, the pump is compatible with commercial solutions in terms of interfaces for connection between engine systems and pump. A concept prototype of the product was obtained in order to better evaluate the validity of the concept. The developed concept represents an innovation in oil pumps design, being unique in its mechanical system for variable displacement delivery.

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This paper contributes to the literature on balance-of-payments constrained growth by investigating how structural change identified with changes in the sectoral composition of exports and imports affects the external constraint We test both the original and a multisectoral version of Thirlwall`s law for a sample of Latin American and Asian countries The original Thirlwall s law is found to hold for all sample countries except South Korea, whereas the multisectoral analogue holds for all of them As the sectoral composition of exports and imports is found to matter for growth we analyze the evolution of each country`s weighted trade income elasticities

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The fall armyworm, Spodoptera frugiperda, is one of the major field pests for maize production. It is mainly controlled by means of synthetic, and more recently by resistant cultivar of maize expressing Bt toxins. The neem tree, Azadirachta indica, is a plant that can potentially control insects with the advantage of being food and environmental safe. The aim of this study was to assess the effect of neem oil on the development and survival of S. frugiperda caterpillars by assessing histological alterations caused on their midgut. Newly hatched caterpillars were submitted to three neem oil concentrations: 0.006; 0.05; 0.4%, which were added to their artificial diet. Ten 3rd instar caterpillars, taken from each treatment, were submitted to histological analysis. The alimentary canals from the specimens were fixed in Baker for 12 hours, desiccated and diaphanized in alcohol/xylol (1:1) and xylol. After placing the samples in paraffin, they were sliced in 8 µm sections and stained with hematoxylin-eosin stain. The neem oil added to the diet of S. frugiperda caused total mortality at dose of 0.4% whilst still in the first instars, prolonged the larval and pupal stages, and reduced the pupal weight. Histo-physiological alterations such as degeneration of the epithelial lining of the midgut and in the peritrophic matrix were found at all concentrations of neem oil.

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BACKGROUND Animal model studies have shown that the colon tumour promoting effect of dietary fat depends not only on the amount but on its fatty acid composition. With respect to this, the effect of n9 fatty acids, present in olive oil, on colon carcinogenesis has been scarcely investigated. AIMS To assess the effect of an n9 fat diet on precancer events, carcinoma development, and changes in mucosal fatty acid composition and prostaglandin (PG)E2 formation in male Sprague-Dawley rats with azoxymethane induced colon cancer. METHODS Rats were divided into three groups to receive isocaloric diets (5% of the energy as fat) rich in n9, n3, or n6 fat, and were administered azoxymethane subcutaneously once a week for 11 weeks at a dose rate of 7.4 mg/kg body weight. Vehicle treated groups received an equal volume of normal saline. Groups of animals were colectomised at weeks 12 and 19 after the first dose of azoxymethane or saline. Mucosal fatty acids were assessed at 12 and 19 weeks. Aberrant crypt foci and the in vivo intracolonic release of PGE2 were assessed at week 12, and tumour formation at week 19. RESULTS Rats on the n6 diet were found to have colonic aberrant crypt foci and adenocarcinomas more often than those consuming either the n9 or n3 diet. There were no differences between the rats on the n9 and n3 diets. On the other hand, administration of both n9 and n3 diets was associated with a decrease in mucosal arachidonate concentrations as compared with the n6 diet. Carcinogen treatment induced an appreciable increase in PGE2 formation in rats fed the n6 diet, but not in those fed the n3 and n9 diets. CONCLUSIONS Dietary olive oil prevented the development of aberrant crypt foci and colon carcinomas in rats, suggesting that olive oil may have chemopreventive activity against colon carcinogenesis. These effects may be partly due to modulation of arachidonic acid metabolism and local PGE2synthesis.

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This paper investigates a topic of the agenda about growth models, emphasizing the elaboration of an external constrained model with endogenous elasticity, with an emphasis on real exchange rate level as main tool for the economic development. The model is anchored in Kaldor, Thirlwall and Barbosa Filho's models and it will demonstrate that external constraint changes in the course of time.

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Development of external genitalia in mammalian embryos requires tight coordination of a complex series of morphogenetic events involving outgrowth, proximodistal and dorsoventral patterning, and epithelial tubulogenesis. Hypospadias is a congenital defect of the external genitalia that results from failure of urethral tube closure. Although this is the second most common birth defect in humans, affecting one in every 250 children, the molecular mechanisms that regulate morphogenesis of the mammalian urethra are poorly understood. We report that mice lacking the IIIb isoform of fibroblast growth factor receptor 2 (Fgfr2) exhibit severe hypospadias. Urethral signaling regions, as indicated by Shh and Fgf8 expression, are established in Fgfr2-IIIb null mice; however, cell proliferation arrests prematurely and maturation of the urethral epithelium is disrupted. Fgfr2-IIIb(-/-) mutants fail to maintain the progenitor cell population required for uroepithelial renewal during tubular morphogenesis. In addition, we show that antagonism of the androgen receptor (AR) leads to loss of Fgfr2-IIIb and Fgf10 expression in the urethra, and an associated hypospadias phenotype, suggesting that these genes are downstream targets of AR during external genital development. Genitourinary defects resulting from disruption of AR activity, by either genetic or environmental factors, may therefore involve negative regulation of the Fgfr2 pathway. This represents the first example of how the developing genitourinary system integrates cues from systemically circulating steroid hormones with a locally expressed growth factor pathway.

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This work analyses the ability of National States and regions have to formulations development strategies. Redeeming the initial development concept as a conflictual process, the hypothesis is that it presents internal and external constraints, as the latter have a higher preponderance, revealed the role played by money. In this case, one can point to as sub-hypothesis that the growth models with external constraint, mainly through the balance of payments, may illustrate the fact that countries are subject to international economic interactions that limit the possibility of bringing acylating strategies well successful in overcoming backwardness. For the specific case of regions, indicates that the external constraint remains an element of embarrassment for regional development, but redeems itself the center-periphery relations in this context to discuss the role of monetary and financial system as an explanation for the disparities regional income. On the domestic front, we highlight the importance of social structures of accumulation as an element of internal cohesion necessary to achieve successful development trajectories. It points also to the importance of the State in the process rescuing some of the main theoretical contributions of the political economy of development, incorporating the concept of globalization on theoretical frameworks presented. This construction where development depends on the actions of external and internal conditions, where money plays a key role as a guideline for reflections on regional development. The attempt was to transplant our considerations on the general development to address the case of regions. Finally, we conclude by greater confidence in the hypothesis and sub-hypotheses of departure, which led to propositions of economic policies

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The purpose of this study was to investigate the effects of an imposed external auditory constraint upon the temporal organization of walking. Ten subjects were videotaped walking normally (N) and with instructions to couple naturally, at mid-swing, or at toe-off to a metronome beat. Based upon an analysis of variance and post hoc Scheffe tests most temporal variables were not significantly different among conditions. The duration of swing phase was significantly different between natural coupling and toe-off. The deviation from the metronome beat was significantly different between the natural coupling and both mid-swing and toe-off. Subjects generally were not successful in achieving coupling during the latter conditions. Thigh and shank phase portraits were used to describe the system's organization to the external constraint.

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Includes bibliography

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This Doctoral Dissertation is triggered by an emergent trend: firms are increasingly referring to investments in corporate venture capital (CVC) as means to create new competencies and foster the search for competitive advantage through the use of external resources. CVC is generally defined as the practice by non-financial firms of placing equity investments in entrepreneurial companies. Thus, CVC can be interpreted (i) as a key component of corporate entrepreneurship - acts of organizational creation, renewal, or innovation that occur within or outside an existing organization– and (ii) as a particular form of venture capital (VC) investment where the investor is not a traditional and financial institution, but an established corporation. My Dissertation, thus, simultaneously refers to two streams of research: corporate strategy and venture capital. In particular, I directed my attention to three topics of particular relevance for better understanding the role of CVC. In the first study, I moved from the consideration that competitive environments with rapid technological changes increasingly force established corporations to access knowledge from external sources. Firms, thus, extensively engage in external business development activities through different forms of collaboration with partners. While the underlying process common to these mechanisms is one of knowledge access, they are substantially different. The aim of the first study is to figure out how corporations choose among CVC, alliance, joint venture and acquisition. I addressed this issue adopting a multi-theoretical framework where the resource-based view and real options theory are integrated. While the first study mainly looked into the use of external resources for corporate growth, in the second work, I combined an internal and an external perspective to figure out the relationship between CVC investments (exploiting external resources) and a more traditional strategy to create competitive advantage, that is, corporate diversification (based on internal resources). Adopting an explorative lens, I investigated how these different modes to renew corporate current capabilities interact to each other. More precisely, is CVC complementary or substitute to corporate diversification? Finally, the third study focused on the more general field of VC to investigate (i) how VC firms evaluate the patent portfolios of their potential investee companies and (ii) whether the ability to evaluate technology and intellectual property varies depending on the type of investors, in particular for what concern the distinction between specialized versus generalist VCs and independent versus corporate VCs. This topic is motivated by two observations. First, it is not clear yet which determinants of patent value are primarily considered by VCs in their investment decisions. Second, VCs are not all alike in terms of technological experiences and these differences need to be taken into account.

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The crossroads of urban development and improved technology allowing oil and gas development in new areas can result in contentious community issues. The debate over one of the improved technologies – i.e., hydraulic fracturing – can be highly emotional. Consequently, industry must address community issues, earning trust and therefore a “social license to operate.” This paper provides fundamental knowledge of the social license to operate concept, validates its application to the oil and gas industry, particularly with respect to shale gas development, discusses the current status of social license in the unconventional development sphere, analyzes current ongoing efforts for shale gas developers to monitor and establish a social license, and identifies potential new methods of encouraging, establishing, and monitoring a social license to operate. The paper also proposes a new institutional framework in which to promote the social license to operate, “The Center for Social License to Operate in the Oil & Gas Industry.”

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This thesis contributes to the paucity of marketing research into the area of internal marketing. Drawing from knowledge developed in a diverse range of marketing and management literatures, the domaill of internal marketing is clarified Gild a new concept, internal market orientation is developed. A new instrument, measuring the internal market orientation, is developed and subjected to standard scale development procedures. Six dimensions of the construct are confirmed; collegial interaction, group interaction, jorlllal interaction, external envirollment, wage flexibility and job flexibility. A sample of 766 UK retail store managers are surveyed to identify levels of internal market orientation and external market orientation in large UK multi-product, multi-site retailers and the structural relationships between internal market orientation, extemal market orientation alld company performance are examined. The external market orientation construct is applied to the local retail market and established measurement instruments adapted to this pwpose. Three measures of performance are employed ill this study. The structural relationships between the six dimensions of internal market orientation and the three dimensions of external market orientation are examined employing structural equations methodology, using LISREL 8.3. alld the impact of internal market orientation Oil external market orientation and company performance is measured. The study finds no direct link between internal market orientation and financial performance but does identify the moderated role of internal market orientation on financial performance. Significant relationships between three of the six dimensions of internal market orientation and the three dimensions of external market orientation are identified and the impact of internal market orientation on the retention of employees and their behaviour is also identified. The research findings contribute to marketing theory by providing empirical evidence to support the long held assumption that internal marketing has an impact on marketing success and offers an explanation of the mechanism by which this influence operates. For marketing practitioners, the research findings offer additional information on which services marketing strategies may be formulated.

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The Bakken region of North Dakota and Montana has experienced perhaps the greatest effects of increased oil and gas development in the United States, with major implications for local governments. Though development of the Bakken began in the early 2000s, large-scale drilling and population growth dramatically affected the region from roughly 2008 through today. This case study examines the local government fiscal benefits and challenges experienced by Dunn County and Watford City, which lie near the heart of the producing region. For both local governments, the initial growth phase presented major fiscal challenges due to rapidly expanding service demands and insufficient revenue. In the following years, these challenges eased as demand for services slowed due to declining industry activity and state tax policies redirected more funds to localities. Looking forward, both local governments describe their fiscal health as stronger because of the Bakken boom, though higher debt loads and an economy heavily dependent on the volatile oil and gas industry each pose challenges for future fiscal stability.

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Nowadays the development of new Internal Combustion Engines is mainly driven by the need to reduce tailpipe emissions of pollutants, Green-House Gases and avoid the fossil fuels wasting. The design of dimension and shape of the combustion chamber together with the implementation of different injection strategies e.g., injection timing, spray targeting, higher injection pressure, play a key role in the accomplishment of the aforementioned targets. As far as the match between the fuel injection and evaporation and the combustion chamber shape is concerned, the assessment of the interaction between the liquid fuel spray and the engine walls in gasoline direct injection engines is crucial. The use of numerical simulations is an acknowledged technique to support the study of new technological solutions such as the design of new gasoline blends and of tailored injection strategies to pursue the target mixture formation. The current simulation framework lacks a well-defined best practice for the liquid fuel spray interaction simulation, which is a complex multi-physics problem. This thesis deals with the development of robust methodologies to approach the numerical simulation of the liquid fuel spray interaction with walls and lubricants. The accomplishment of this task was divided into three tasks: i) setup and validation of spray-wall impingement three-dimensional CFD spray simulations; ii) development of a one-dimensional model describing the liquid fuel – lubricant oil interaction; iii) development of a machine learning based algorithm aimed to define which mixture of known pure components mimics the physical behaviour of the real gasoline for the simulation of the liquid fuel spray interaction.