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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.
371

Foreign Direct Investment in Mexico : Possible Effects on the Economic Growth

Geijer, Karl January 2009 (has links)
<p> </p><p>The purpose of this paper is to examine whether foreign direct investment, FDI, has any impact on economic growth in Mexico. In order to find a possible connection I use a multiple regression analysis with GDP per capita as dependent variable. Furthermore, I critically examine previous studies of FDI and its effect on GDP per capita in Mexico as well as other studies with several developed and developing countries. The difference between this paper and previous studies is that the data is more up-to-date here. My results, like most of the previous studies, do not indicate on any statistical significance that FDI has a positive effect on economic growth. FDI do however seem to produce positive spillover effects on the domestic economy, mainly through knowledge and technological spillovers.</p><p> </p><p> </p>
372

Bearing options, including design and testing, for direct drive linear generators in wave energy converters

Caraher, Sarah January 2011 (has links)
The key focus of this research was to investigate the bearing options most suited to operation in a novel direct drive linear generator. This was done through bearing comparisons, modelling and testing. It is fundamental that the linear generator is designed to suit the marine environment. Key design constraints include reliability, survivability, maintenance intervals and cost. Resilient mechanical structural components, such as bearings, will prolong the time a device can operate without maintenance hence prolonging the operating period. Effective lifespan predictions for bearings will feed into the structural design of the generator which forms part of an overall objective to combine each generator design stage into one integrated design process. This promises to provide a cost effective, light weight generator design. This thesis covers the initial investigations into effective, long life and low-wear bearings to meet the operating demands of WEC. It includes an assessment of conventional bearing technology, designs of water-fed hydrostatic bearings and testing of novel polymer bearings. The development of an experimental test rig from a prototype linear generator is described. The rig was built in order to validate and fully explore the potential of self-lubricating, submersible polymer bearings with the ultimate aim of identifying wear constants and frictional properties of the bearings in the low-speed, mid to high-load, oscillating operation of a WEC in order to more accurately predict a bearing lifespan. The outcome of this research served to underpin the need for the design of application specific bearing systems to be based on empirically determined data and observations from test data taken from application specific tests. For inclusion in the design of these linear generators, sizing a bearing requires knowledge of the electrical loading in addition to the expected operating conditions of a WEC. Choosing bearing materials and hence lubricant regimes is dependant on the thermal operating characteristics. Then bearing knowledge in terms of size, load capacity and lifespan can be put directly into the structural model. This iterative process of design can then be merged into a fully integrated generator design tool hence this research was part of the development of an integrated design tool for direct drive generators.
373

AN ECONOMIC ANALYSIS OF A LATIN AMERICAN UNIVERSITY: THE INTERNATIONAL APPLICATION OF UNITED STATES COSTING TECHNIQUES (MEXICO).

Ahumada, Martín Miguel January 1983 (has links)
The purpose of this study was to conduct an in-depth examination of factors associated with instructional cost variations among the academic units of a private, Mexican university, the Universidad de Monterrey (UDEM). The study also sought to understand the differences between this university's income and expenditure patterns and those of most comparable institutions in the United States. The analysis enabled the University to identify where it may be more efficient and, in what may turn out to be of most significance, provided it with a higher level of institutional self-awareness. The framework for this study utilized the concepts of the production function and cost theory, both borrowed from microeconomics. Three measures of instructional costs (cost per student-credit-hour, cost per full-time-student-equivalent, and cost per course) were regressed on a series of independent variables that were hypothesized to influence instructional costs. The study utilized the data classification and coding procedures developed by the National Association of College and University Business Officers (NACUBO) and the National Center for Higher Education Management Systems (NCHEMS). Differences in unit instructional costs among UDEM's academic units were largely due to differences in student-faculty ratios, average class sizes, and total number of courses taught (direct costs), and average salaries for clerical and administrative staff (indirect costs). These findings imply that UDEM may increase efficiency through curricular retrenchment and by increasing faculty productivity levels. The University's enrollment (2,300 at the university level) is very small for its broad liberal arts, professional and graduate curriculum. In comparing UDEM's income and expenditure patterns to those of most comparable U.S. institutions, it was found that UDEM depended more heavily on tuition and fees for income and, as such, either had not pursued or not been successful in obtaining other revenue. Yet, the University was able to devote a larger share of its revenue to instruction than were comparable U.S. institutions. In addition, UDEM provided relatively more support to its academic support function while rendering few resources for scholarships and fellowships. These results suggest that UDEM might benefit greatly from a well-designed fund-raising effort and that a student aid program targeted on low income students could yield additional income while expanding student opportunity and building public relations.
374

Synthesis of multi-metallic catalysts for fuel cell applications.

Naidoo, Sivapregasen. January 2008 (has links)
<p>The direct methanol fuel cell or DMFC is emerging as a promising alternative energy source for many applications. Developed and developing countries, through research, are fast seeking a cheap and stable supply of energy for an ever-increasing number of energy-consuming portable devices. The research focus is to have DMFCs meeet this need at an affordable cost is problematic. There are means and ways of making this a reality as the DMFC is found to be complementary to secondary batteries when used as a trickle charger, full charger, or in some other hybrid fuel cell combination. The core functioning component is a catalyst containing MEA, where when pure platinum is used, carbon monoxide is the thermodynamic sink and poisons by preventing further reactions at catalytic sites decreasing the life span of the catalyst if the CO is not removed. Research has shown that the bi-functional mechanism of a platinum-ruthenium catalyst is best because methanol dehydrogenates best on platinumand water dehydrogenation is best facilitated on ruthenium. It is also evident that the addition of other metals to that of PtRu/C can make the catalyst more effective and effective and increase the life span even further. In addition to this, my research has attempted to reduce catalyst cost for DMFCs by developing a low-cost manufacturing technique for catalysts, identify potential non-noblel, less expensive metallic systems to form binary, ternary and quarternary catalysts.</p>
375

Evaluating canola genotypes and harvest methods to reduce seedbank addition and longevity

2013 April 1900 (has links)
Seed loss in canola (Brassica napus, Brassica rapa and Brassica juncea) leads to considerable loss of revenue and dispersal of canola seeds into the soil seedbank. Once canola seeds enter the soil seedbank a portion can become secondarily dormant and persist for many years creating volunteer weed problems in following crops. Reducing canola seed loss and seedbank persistence can be an important strategy to reduce the incidence of volunteer weeds. The primary hypothesis of this research was that canola seedbank addition and dormancy induction in the seed are affected by genotype and harvest method. To test this hypothesis, three studies were conducted with the following objectives: i) to determine canola seedbank addition from windrowing and direct-harvesting operations on commercial farms in western Canada, ii) to determine agronomic- and harvest-related factors that may increase seed loss in canola, iii) to determine the effect of stage of crop maturity at harvest on potential to develop seed dormancy in canola, iv) to evaluate canola genotypes and harvest methods to reduce canola seedbank addition. A total of 66 canola fields were surveyed across Saskatchewan in 2010 and 2011. Shattered seeds from these fields were sampled within 3 weeks of harvest by using a vacuum cleaner. Agronomic- and harvest-related data were collected for each field using questionnaires. In a separate small plot study the effects of harvest methods (windrowing and direct-harvesting) and pod sealant products (Pod-Stik® and Pod Ceal DC®) on seed loss in five canola genotypes (InVigor5440, RR45H26, InVigor5020, RR4362, and CL8571) were evaluated in 2010 and 2011. In both years, 6 harvest samples were collected weekly from InVigor5440 and InVigor5020 genotypes starting at early stage of crop maturity until harvest to assess the effect of seed maturity on dormancy induction. On commercial farms, the average seedbank addition was 5,821 viable seeds m-2, which was equivalent to 7.3% of the total seed yield. There was no difference in the reported yield and seedbank addition between windrowed and direct-harvested canola on commercial farms. But in the small plot study, windrowing resulted in higher seedbank addition. Higher seedbank addition was observed when the yield of canola was higher and when producers had a larger area seeded to canola. The observed seedbank addition was also higher in Roundup Ready genotypes and when a conventional combine harvester was used to harvest canola. Little primary dormancy and low potential to secondary dormancy induction was observed in InVigor5440 and InVigor5020 seeds at an early stage of crop maturity. But at full maturity seeds of both genotypes had no primary dormancy but showed high potential for secondary dormancy induction. This indicates that windrowing the evaluated genotypes at early stage of crop maturity lowered the potential for secondary dormancy induction. There were appreciable differences in seedbank addition among the evaluated canola genotypes but pod sealant products did not affect seed yield and seed shatter in canola. The results of this study suggest that canola seedbank addition can be minimized by growing genotypes having reduced seed loss and with the adoption of direct-harvesting operations.
376

Direct Fitting of Analytical Potential Functions to Diatomic Molecular Spectroscopic Data

Seto, Jenning January 2000 (has links)
The standard practice of spectroscopic data reduction is generally to fit data to level energy expansions in terms of the vibrational and rotational quantum numbers. However, the utility of such expressions is limited because they extrapolate poorly and they need very large sets of parameters, many of which have no independent physical significance. One method of addressing these problems is to fit the spectroscopic data directly to analytical potential energy functions incorporating the natural physical behaviour of the molecule in question. Although there have been a number of successful applications of this approach, there are still certain problems associated with the types of potential forms being used. This thesis will explore some of these problems and determine how effective the potential forms being used are for a number of specific cases.
377

Structural optimisation of permanent magnet direct drive generators for 5MW wind turbines

Zavvos, Aristeidis January 2013 (has links)
This thesis focuses on permanent magnet "direct drive" electrical generators for wind turbines with large power output. A variety of such generator topologies is reviewed, tested and optimised in an attempt to increase their potential as commercial concepts for the wind industry. Direct drive electrical generators offer a reliable alternative to gearbox drivetrains. This novel technology reduces energy loses thus allowing more energy to be yield from the wind and decreases the maintenance cost at the same time. A fundamental issue for these generators is their large size which makes them difficult to manufacture, transport and assembly. A number of structural designs have been suggested in the literature in an attempt to minimise this attribute. A set of design tools are set out in an attempt to investigate the structural stiffness of the different permanent magnet direct drive generator topologies against a number of structural stresses that apply to such wind turbine energy converters. Optimisation techniques, both analytical and structural, are also developed for minimising the total mass of a variety of "directly driven" machines with power output of 5MW or greater. Conventional and promising generator designs are modelled and optimised with the use of these optimisation techniques. The topologies under examination are then compared in terms of structural mass, stiffness and cost. As the number of wind turbine manufactures who adopt the direct drive concept increases, it is important to outline the unique characteristics of the different topologies and increase their manufacturing potential. Discussions and conclusions will provide an indication of the design solutions that could help decrease the mass and cost of such machines.
378

Study of turbulence and wall shear stress in unsteady flow over smooth and rough wall surfaces

Seddighi-Moormani, Mehdi January 2011 (has links)
Flows over hydraulically smooth walls are predominant in turbulence studies whereas real surfaces in engineering applications are often rough. This is important because turbulent flows close to the two types of surface can exhibit large differences. Unfortunately, neither experimental studies nor theoretical studies based on conventional computational fluid dynamics (CFD) can give sufficiently accurate, detailed information about unsteady turbulent flow behaviour close to solid surfaces, even for smooth wall cases. In this thesis, therefore, use is made of a state of the art computational method “Direct Numerical Simulation (DNS)” to investigate the unsteady flows. An “in-house” DNS computer code is developed for the study reported in this thesis. Spatial discretization in the code is achieved using a second order, finite difference method. The semi-implicit (Runge-Kutta & Crank-Nicholson) time advancement is incorporated into the fractional-step method. A Fast Fourier Transform solver is used for solving the Poisson equation. An efficient immersed Boundary Method (IBM) is used for treating the roughness. The code is parallelized using a Message Passing Interface (MPI) and it is adopted for use on a distributed-memory computer cluster at University of Aberdeen as well as for use at the UK’s national high-performance computing service, HECToR. As one of the first DNS of accelerating/decelerating flows over smooth and rough walls, the study has produced detailed new information on turbulence behaviours which can be used for turbulence model development and validations. The detailed data have enabled better understanding of the flow physics to be developed. The results revealed strong non-equilibrium and anisotropic behaviours of turbulence dynamics in such flows. The preliminary results on the rough wall flow show the response of turbulence in the core and wall regions, and the relationship between the axial and the other components are significantly different from those in smooth wall flows.
379

An Optimal Control Toolbox for MATLAB Based on CasADi

Leek, Viktor January 2016 (has links)
Many engineering problems are naturally posed as optimal control problems. It may involve moving between two points in the fastest possible way, or to put a satellite into orbit with minimum energy consumption. Many optimal control problems are too difficult to be solved analytically and therefore require the use of numerical methods. The numerical methods that are the most widespread are the so-called direct methods. However, there is one major drawback with these. If the problem is non-convex, the solution is not guaranteed globally optimal, that is, the absolute best, instead it is guaranteed locally optimal, that is the best in its vicinity. To compensate for this, the problem should be solved several times, under different conditions, in order to investigate whether the solution is a good candidate for the global optimum. CasADi is a software specifically designed for dynamic optimization. It has gained wide spread in recent years because it provides all the necessary building blocks for dynamic optimization. This has given individual engineers and scientists the ability to independently formulate and solve all sorts of optimal control problems. However, this requires good theoretical knowledge of the necessary numerical methods. The advantage of a toolbox, which solves general optimal control problems, is that the underlying numerical methods have been tested and shown to function on optimal control problems with known solutions. This means that the user does not need exhaustive knowledge of the numerical methods involved, but can focus on formulating and solving optimal control problems. The main contribution of this thesis is an optimal control toolbox for MATLAB based on CasADi. The toolbox does not require expert knowledge of the numerical methods, but provides an alternative lower level abstraction that allows for more complex problem formulations. The toolbox implements two direct methods, direct multiple shooting and direct collocation. This allows a problem formulation with many degrees of freedom. The most important property of the toolbox is that the discretization can be changed, without the problem formulation needing to be altered. This way the user can easily change the conditions for his/her problem. The thesis describes how the two implemented direct methods work, and the design choices made. It also describes what remains to test and evaluate, and the problems that have been used as a reference during the development process.
380

Edge-Transitive Bipartite Direct Products

Crenshaw, Cameron M 01 January 2017 (has links)
In their recent paper ``Edge-transitive products," Hammack, Imrich, and Klavzar showed that the direct product of connected, non-bipartite graphs is edge-transitive if and only if both factors are edge-transitive, and at least one is arc-transitive. However, little is known when the product is bipartite. This thesis extends this result (in part) for the case of bipartite graphs using a new technique called "stacking." For R-thin, connected, bipartite graphs A and B, we show that A x B is arc-transitive if and only if A and B are both arc-transitive. Further, we show A x B is edge-transitive only if at least one of A, B is also edge-transitive, and give evidence that strongly suggests that in fact both factors must be edge-transitive.

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