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
Hypersonic vehicles, which flight at Mach numbers greater than 5, will serve as a more convenient and efficient transport tool than present subsonic airplanes for long-distance jour- neys in future. Typically, it only...Hypersonic vehicles, which flight at Mach numbers greater than 5, will serve as a more convenient and efficient transport tool than present subsonic airplanes for long-distance jour- neys in future. Typically, it only takes a couple of hours from Beijing to New York at hypersonic speed. Recent interest in these vehicles has grown intensively, and various types of in- novative designs have been proposed and studied. Despite entering the age of hypersonic flight, there still exist many problems to resolve [1-4]. How to design an advanced aero- dynamic configuration is one of them [5].展开更多
This paper represents the performance analysis of the different shapes of antenna balun and feeding techniques for step constant tapered slot antenna. This work also addresses the benefits of antenna balun (circular a...This paper represents the performance analysis of the different shapes of antenna balun and feeding techniques for step constant tapered slot antenna. This work also addresses the benefits of antenna balun (circular and rectangular) along with two types of feeding techniques (Microstrip line L-shape and Microstrip line I-shape). The performance of the antenna for each technique is thoroughly investigated using Computer Simulation Technology (CST) Microwave Studio software simulation under the resonant frequency of 5.9 GHz. Results demonstrate that the proposed model is an effective tool for improving antenna performance. Moreover, an extensive comparison has been carried out between the two different shapes, with and without antenna balun and between two feeding techniques focusing on return losses, gain, directivity, and voltage standing wave ratio (VSWR).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.
基金supported by the National Natural Science Foundation of China(Grant Nos.11372324,and 11572333)the State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences(Grant Nos.LHD2017TC01,LHD2017MS04,and LHD2017QN03)
文摘Hypersonic vehicles, which flight at Mach numbers greater than 5, will serve as a more convenient and efficient transport tool than present subsonic airplanes for long-distance jour- neys in future. Typically, it only takes a couple of hours from Beijing to New York at hypersonic speed. Recent interest in these vehicles has grown intensively, and various types of in- novative designs have been proposed and studied. Despite entering the age of hypersonic flight, there still exist many problems to resolve [1-4]. How to design an advanced aero- dynamic configuration is one of them [5].
文摘This paper represents the performance analysis of the different shapes of antenna balun and feeding techniques for step constant tapered slot antenna. This work also addresses the benefits of antenna balun (circular and rectangular) along with two types of feeding techniques (Microstrip line L-shape and Microstrip line I-shape). The performance of the antenna for each technique is thoroughly investigated using Computer Simulation Technology (CST) Microwave Studio software simulation under the resonant frequency of 5.9 GHz. Results demonstrate that the proposed model is an effective tool for improving antenna performance. Moreover, an extensive comparison has been carried out between the two different shapes, with and without antenna balun and between two feeding techniques focusing on return losses, gain, directivity, and voltage standing wave ratio (VSWR).
