铁塔腿部采取 V 面设计的塔型一般都用在受力较大的转角塔和较高的直线跨越塔。由于 V 面计算与实物存在不同差异,设计单位通常不标注数据和加工尺寸,即使标注了尺寸也仅仅是为了估算材料重量而不能用作放样时的尺寸数据。因此,放样时...铁塔腿部采取 V 面设计的塔型一般都用在受力较大的转角塔和较高的直线跨越塔。由于 V 面计算与实物存在不同差异,设计单位通常不标注数据和加工尺寸,即使标注了尺寸也仅仅是为了估算材料重量而不能用作放样时的尺寸数据。因此,放样时还要计算实际准确的尺寸数据。塔腿 V 面放样的控制尺寸,其关键不在于计算过程而在于图面的分析是否恰当准确,本文介绍的分析过程可供铁塔设计和制作的参考。展开更多
The main aim of this research is to optimize the tensile strength of laser welded FeCo-V alloy.A mathematicalrelationship was developed to predict tensile strength of the laser beam welded FeCo-V foils by incorporatin...The main aim of this research is to optimize the tensile strength of laser welded FeCo-V alloy.A mathematicalrelationship was developed to predict tensile strength of the laser beam welded FeCo-V foils by incorporating process parameterssuch as lamping current,welding speed,pulse duration and focused position.The procedure was established to improve the weldstrength and increase the productivity.The results indicate that the pulse duration and welding speed have the greatest influence ontensile strength.The obtained results showed that the tensile strength of the weld joints increase as a function of increasing pulseduration reaching to a maximum at a pulse duration value of2.25ms.Moreover,the tensile strength of joints increases with decreasein welding speed reaching to a maximum at a welding speed of125mm/min.It has been shown that increase in pulse duration anddecrease in welding speed result in increased effective peak power density and hence formation of more resistant welds.At higherpulse durations and lower welding speeds,the tensile strength of weld joints decreases because of formation of solidificationmicrocracks in the fusion zone.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
For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields ...For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields the derivation of SiOC.This causes a significant degradation of the 4H SiC surface characteristics according to the results of surface composition analysis.As validity,Ni/SiC ohmic contact measurement illustrates a higher specific contact resistance than the normal value by a factor of 2～3.Consequently the MESFET fabricated with this kind of 4H SiC material results in a degraded I V output performance compared with that of normal 4H SiC MESFET.展开更多
文摘铁塔腿部采取 V 面设计的塔型一般都用在受力较大的转角塔和较高的直线跨越塔。由于 V 面计算与实物存在不同差异,设计单位通常不标注数据和加工尺寸,即使标注了尺寸也仅仅是为了估算材料重量而不能用作放样时的尺寸数据。因此,放样时还要计算实际准确的尺寸数据。塔腿 V 面放样的控制尺寸,其关键不在于计算过程而在于图面的分析是否恰当准确,本文介绍的分析过程可供铁塔设计和制作的参考。
文摘The main aim of this research is to optimize the tensile strength of laser welded FeCo-V alloy.A mathematicalrelationship was developed to predict tensile strength of the laser beam welded FeCo-V foils by incorporating process parameterssuch as lamping current,welding speed,pulse duration and focused position.The procedure was established to improve the weldstrength and increase the productivity.The results indicate that the pulse duration and welding speed have the greatest influence ontensile strength.The obtained results showed that the tensile strength of the weld joints increase as a function of increasing pulseduration reaching to a maximum at a pulse duration value of2.25ms.Moreover,the tensile strength of joints increases with decreasein welding speed reaching to a maximum at a welding speed of125mm/min.It has been shown that increase in pulse duration anddecrease in welding speed result in increased effective peak power density and hence formation of more resistant welds.At higherpulse durations and lower welding speeds,the tensile strength of weld joints decreases because of formation of solidificationmicrocracks in the fusion zone.
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For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields the derivation of SiOC.This causes a significant degradation of the 4H SiC surface characteristics according to the results of surface composition analysis.As validity,Ni/SiC ohmic contact measurement illustrates a higher specific contact resistance than the normal value by a factor of 2～3.Consequently the MESFET fabricated with this kind of 4H SiC material results in a degraded I V output performance compared with that of normal 4H SiC MESFET.
