Interaction of various components in rotating machinery like gearboxes may generate excitation forces at various frequencies. These frequencies may sometimes overlap with the frequencies of the forces generated by other components in the system. Conventional vibration spectrum analysis does not attenuate noise and spectral frequency band overlapping, which in many applications masks the changes in the structural response caused by the deterioration of certain components in the machine. This problem is overcome by the use of time domain averaging (dsynchronous averaging). In time domain averaging, the vibration signal is sampled at a frequency that is synchronized with the rotation of the gear of interest and the samples obtained for each singular position of the gear are ensemble-averaged. When sufficient averages are taken, all the vibration from the gearbox, which is asynchronous with the vibration of the gear, is attenuated. The resulting time synchronously averaged signal obtained through this process indicates the vibration produced during one rotation of the monitored gear. This direct time domain averaging process essentially acts as a broadband noise synchronous filter, which filters out the frequency content that is asynchronous with the vibration of the gear of interest provided that enough averages are taken. The time domain averaging procedure requires an enormous amount of vibration data to execute, making it very difficult to develop online gearbox condition monitoring systems that make use of time domain averaging to enhance their diagnostic capabilities since data acquisition and analysis cannot be done simultaneously. The objective of this research was to develop a more efficient way for calculating the time domain average of a gear vibration signal. A study of Artificial Neural Networks (ANNs) and Support Vector Machines (SVMs) was conducted to assess their suitability for use in time domain averaging. Two time domain averaging models that use ANNs and SVMs were developed. Model 1 uses a single feedforward network configuration to map the input which are rotation synchronized gear vibration signals to the output which is the time domain average of the gear vibration signal, using only a section of the input space. Model 2 operates in two stages. In the first stage, it uses a feedforward network to predict the instantaneous time domain average of the gear vibration after 10 inputs (10 rotation synchronized gear vibration signals) to predict the instantaneous average of the gear rotation. The outputs from the first state are used as inputs to the second stage, where a second feedforward network is used to predict the time domain average of the entire vibration signal. When ANNs and SVMs were implemented, the results indicated that the amount of gear vibration date that is required to calculate the time domain average using Model 1 can be reduced by 75 percent and the amount of gear vibration data that needs to be stored in the data acquisition system when Model 2 is used can be reduced by 83 percent. / Dissertation (M Eng (Mechanical and Aeronautical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

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Goal of the Master Thesis was to design conception of electric vehicle driveline, which is able of torque vectoring between each wheel independently and to design front axle gearbox. The aim was to use up the car on race track and to test dynamic properties of electric vehicle for follow-up development. Due to determined requirements and possible solutions the conception of driveline was designed and basic parameters were defined. The main part of the thesis contains a design of gearbox including strength calculation of gearing, the control of shafts to fatigue and elasticity limiting states, life of selected bearings. Gearbox case was subjected to FEM analysis. The last chapter uses simulation to gain vehicle acceleration. Designed electric driveline is applicable to other sport vehicles after some modifications.

Master thesis deals with design of "student" pneumatic car equipped by pneumatic elements of a chosen firm. The introductory part is devoted to mapping the Hungarian competition. The idea of designing such vehicles comes from this competition. Next step is analysis of vehicles that are present in this competition. The main part describes the development of vehicle from the initial design, through analysis of main components, through to the production and presentation. The work contains a strain-stress analysis of the frame which is made by using the finite element method. The work ends with the conclusion which assesses the results.

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An analysis of the effects of gear shaping with a pinion cutter upon the geometry and root stresses in external spur gears using the finite element method is given. The models analyzed have the shape of a ring with three teeth. The middle tooth is loaded and load sharing has been assumed. Thirty-five finite element models were used for the computation of stress concentration factors in pinion shaped gear teeth. The results for pinion shaped teeth are compared to those results obtained when shaping with a hob. The Dolan and Broghamer stress concentration factor was also calculated for comparison with the results from finite element analysis. The difference in the two was not more than 8%. The results from finite element analysis have been condensed into an empirical expression which gives the stress concentration factor as a function of the dedendum of the pinion, the numbers of teeth on the pinion and cutter, and the number of teeth on the mating gear. A comparison of the bending stress in the root of a tooth shaped by standard pinion and hob cutters indicated no appreciable differences in strength. / M.S.

<p><strong><p>Background:</p><p>what affects company value becomes apparent. The capital structure is the relation between</p><p>borrowed capital and equity in a company´s financing mix. What impact changes in capital structure</p><p>have on company value is a widely debated subject within the theory of finance. If a relationship</p><p>between capital structure and company value exists the implication is that an optimal capital</p><p>structure where company value is maximized also exists.</p>During extreme market conditions like the period during fall 2008 the discussion of<strong><p>Aim:</p><p>company value exists among selected stocks and companies listed on Stockholmsbörsens OMXS30.</p>The aim of the thesis is to study whether a certain relationship between capital structure and<strong><p>Implementation:</p><p>performed among chosen stocks and companies. The empirical results eventuating from this have</p><p>been analyzed from the view of elected relevant theory.</p>With aim to fulfill the purpose of the thesis regression analysis has been<strong><p>Completion and results:</p><p>between debt ratio and enterprise value (EV) can be established. During more turbulent periods the</p><p>results is more scattered. The results of this thesis is more evidence that the debt´s gear on equity is</p><p>what mainly impacts price movements on the stock market and affects value, where high debt will</p><p>pay off during favorable conditions and be costly during bad conditions, rather than a specific capital</p><p>structure. A certain relationship between capital structure and company value cannot be established.</p><p>The results of this thesis is also evidence pointing out the difficulties in measuring the relationship</p><p>between two variables where one is the daily quoted market price of equity, which is greatly affected</p><p>by market psychology et cetera, and the other, capital structure, is only to be measured during</p><p>interim- and annual reports.</p>We find that during normal market conditions a positive relationship<strong><p> </p></strong></strong></strong></strong></strong></p>

Background: During extreme market conditions like the period during fall 2008 the discussion of what affects company value becomes apparent. The capital structure is the relation between borrowed capital and equity in a company´s financing mix. What impact changes in capital structure have on company value is a widely debated subject within the theory of finance. If a relationship between capital structure and company value exists the implication is that an optimal capital structure where company value is maximized also exists. Aim: The aim of the thesis is to study whether a certain relationship between capital structure and company value exists among selected stocks and companies listed on Stockholmsbörsens OMXS30. Implementation: With aim to fulfill the purpose of the thesis regression analysis has been performed among chosen stocks and companies. The empirical results eventuating from this have been analyzed from the view of elected relevant theory. Completion and results: We find that during normal market conditions a positive relationship between debt ratio and enterprise value (EV) can be established. During more turbulent periods the results is more scattered. The results of this thesis is more evidence that the debt´s gear on equity is what mainly impacts price movements on the stock market and affects value, where high debt will pay off during favorable conditions and be costly during bad conditions, rather than a specific capital structure. A certain relationship between capital structure and company value cannot be established. The results of this thesis is also evidence pointing out the difficulties in measuring the relationship between two variables where one is the daily quoted market price of equity, which is greatly affected by market psychology et cetera, and the other, capital structure, is only to be measured during interim- and annual reports.

This thesis examines asset pricing and capital structure of small- and medium-sized enterprises (SMEs) in three essays. Firm finance and asset pricing are areas of voluminous research in the literature. Most of this research observes firms trading on public stock exchanges. In my thesis, I examine privately-owned SMEs where relatively little research has been done. I use a proprietary database of over 16,000 SMEs that sold from 1990 to 2010, reporting market valuations and accounting information. My findings contribute to the literature on asset pricing and capital structure of private firms that benefits researchers, entrepreneurs, investors, and analysts. The first essay examines whether the size effect in returns found in traded stocks is present in SMEs. The size-effect literature generally observes listed firms and finds that smaller firms tend to have higher returns. Using the SME database, I document the size effect in private firms using market valuations. I also find the size premium is concentrated in smaller SMEs. In firms smaller than $2.5 million in market value, the size effect is nearly 13 times stronger compared to larger firms. The second essay explores the effects of investor sentiment and marketwide liquidity in SME returns. Prior studies find these factors have effects in returns of listed firms. I find that SME returns are negatively related to sentiment and liquidity. As sentiment or liquidity rise, SME returns tend to fall. This study also finds that the effects of sentiment and liquidity are concentrated in smaller firms and weaken or disappear in larger SMEs. Apparently investors in smaller SMEs are more influenced by sentiment and liquidity. I also find that sentiment and liquidity have conditional effects on the magnitude of the size premium. The third and final essay examines SME capital structure. Firm capital structure has been one of the most contentious issues in finance theory for over 50 years. Relatively little research examines private firm finance and no previous studies to my knowledge have examined SME capital structure using market-based leverage ratios. I examine relations between leverage and capital structure determinants suggested by theory using market-based and book-value leverage ratios. I find support for both the trade-off and pecking-order theories. This study also finds that SMEs tend to use short-term debt much more than long-term debt and firms appear to practice maturity matching where managers tend to match borrowing terms with asset life. Evidence also suggests that capital structure determinants suggested by theory have greater explanatory power for market-based leverage ratios than for ratios based on book values.

The submitted project deals with a complete design of a gearbox of a portable ground power generator designed for preflight preparation of helicopters. The gearbox has been designed to meet given specifications, which are based on required electrical parameters of the entire power unit and with regards to parameters of driving turbine engine. The introductory section deals with a kinematical design of transmission gears with regards to required parameters and design constraints. The kinematical design determines whole concept and resulting form of the gearbox. Next part deals with optimization of gearing, the design of wheel bearing, and design of oil system. The implementation part of the project consists in the engineering design of the gearbox, which was made in 3D environment Pro/Engineer. The design is reviewed and first operational results of manufactured and tested gearbox are discussed in the concluding section of this work.