Despite appropriate design of girder under bending and shear,the deflection of long steel girders usually exceeds the allowable range,and therefore the structural designers encounter challenges in this regard.Consider...Despite appropriate design of girder under bending and shear,the deflection of long steel girders usually exceeds the allowable range,and therefore the structural designers encounter challenges in this regard.Considering significant features of the cables,namely,low weight,small cross section,and high tensile strength,they are used in this research so as to control the deflection of long girder bridges,rather than increasing their heights.In this study,theoretical relations are developed to calculate the increase in pre-tensioning force of V-shaped steel cables under external loading as well as the deflection of steel girder bridges with V-shaped cables and different support conditions.To verify the theoretical relations,the steel girder bridge is modeled in the finite element ABAQUS software with different support conditions without cable and with V-shaped cables.The obtained results show that the theoretical relations can appropriately predict the deflection of girder bridge with V-shaped cables and different support conditions.In this study,the effects of the distance from support on the deflection of mid span are studied in both simply supported and fixed supported girder bridge so as to obtain the appropriate distance from support causing the minimum deflection.展开更多
This paper introduces a new study on the optimum calculation of partial transmission ratios of a mechanical drive system using a V-belt and a three-step helical gearbox in order to get the minimum size of the system. ...This paper introduces a new study on the optimum calculation of partial transmission ratios of a mechanical drive system using a V-belt and a three-step helical gearbox in order to get the minimum size of the system. The chosen objective function was the cross section dimension of the system. In solving the optimization problem, the design equation for pitting resistance of a gear set was investigated and equations on moment equilibrium condition of a mechanic system including a V-belt and three helical gear units and their regular resistance condition were analysed. From the results of the study, effective formulas for determination of the partial ratios of the V-belt and three-step helical gearboxes were introduced. As using explicit models, the partial ratios can be determined accurately and simply.展开更多
Firm level empirical research on the impact of financing decisions on small business performance is scarce in the Australian context. This study adopts an instrument variable （IV） approach to analyze the impact of f...Firm level empirical research on the impact of financing decisions on small business performance is scarce in the Australian context. This study adopts an instrument variable （IV） approach to analyze the impact of financing decisions, in particular, equity or debt are obtained, on the performance of small businesses by using the panel data from Australian Bureau of Statistics （ABS） Business Longitudinal Database （BLD） 2004-2005, 2005-2006, and 2006-2007. Performance variables, i.e., sales and expenditure, are used as dependent variables. Equity and debt obtained are used as independent variables （or known as treatments）. IV includes size of the business, age of the business, number of locations, and industry division etc.. The results from IV modeling outperformed those obtained from OLS （Ordinary Least Squares）. Findings include： （1） financing has significantly positive impacts on the performance of small businesses in Australia; （2） equity and debt financing are used as alternatives, comparatively, equity financing is preferred; （3） capital purchases are largely funded by debt financing, while non-capital purchases and salary expenses are funded by equity financing; and （4） equity financing is more often used by firms with increasing capital purchases and declining non-capital purchases, while debt financing is used by firms with the opposite trends. The paper concludes with a discussion of the limitations of this research and future research＇s directions.展开更多
文摘Despite appropriate design of girder under bending and shear,the deflection of long steel girders usually exceeds the allowable range,and therefore the structural designers encounter challenges in this regard.Considering significant features of the cables,namely,low weight,small cross section,and high tensile strength,they are used in this research so as to control the deflection of long girder bridges,rather than increasing their heights.In this study,theoretical relations are developed to calculate the increase in pre-tensioning force of V-shaped steel cables under external loading as well as the deflection of steel girder bridges with V-shaped cables and different support conditions.To verify the theoretical relations,the steel girder bridge is modeled in the finite element ABAQUS software with different support conditions without cable and with V-shaped cables.The obtained results show that the theoretical relations can appropriately predict the deflection of girder bridge with V-shaped cables and different support conditions.In this study,the effects of the distance from support on the deflection of mid span are studied in both simply supported and fixed supported girder bridge so as to obtain the appropriate distance from support causing the minimum deflection.
文摘This paper introduces a new study on the optimum calculation of partial transmission ratios of a mechanical drive system using a V-belt and a three-step helical gearbox in order to get the minimum size of the system. The chosen objective function was the cross section dimension of the system. In solving the optimization problem, the design equation for pitting resistance of a gear set was investigated and equations on moment equilibrium condition of a mechanic system including a V-belt and three helical gear units and their regular resistance condition were analysed. From the results of the study, effective formulas for determination of the partial ratios of the V-belt and three-step helical gearboxes were introduced. As using explicit models, the partial ratios can be determined accurately and simply.
文摘Firm level empirical research on the impact of financing decisions on small business performance is scarce in the Australian context. This study adopts an instrument variable （IV） approach to analyze the impact of financing decisions, in particular, equity or debt are obtained, on the performance of small businesses by using the panel data from Australian Bureau of Statistics （ABS） Business Longitudinal Database （BLD） 2004-2005, 2005-2006, and 2006-2007. Performance variables, i.e., sales and expenditure, are used as dependent variables. Equity and debt obtained are used as independent variables （or known as treatments）. IV includes size of the business, age of the business, number of locations, and industry division etc.. The results from IV modeling outperformed those obtained from OLS （Ordinary Least Squares）. Findings include： （1） financing has significantly positive impacts on the performance of small businesses in Australia; （2） equity and debt financing are used as alternatives, comparatively, equity financing is preferred; （3） capital purchases are largely funded by debt financing, while non-capital purchases and salary expenses are funded by equity financing; and （4） equity financing is more often used by firms with increasing capital purchases and declining non-capital purchases, while debt financing is used by firms with the opposite trends. The paper concludes with a discussion of the limitations of this research and future research＇s directions.
