In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested ...In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested under constant amplitude fatigue loads using a specially designed test rig.The joint was analyzed statically by t e finite element analysis(F3A),and metallographic analysis of fatigue fracture was done by the electron scanning microscope.Numerical simulation and experimental results show that the hot-spot of WCPHSJ lies at the weld toe location where severe stress is concentrated.Fatigue cracks initiate at the weld toe and then propagate circumferentially around the sphere with a diameter equivalent to the width of the cross plate up to the fatigue facture.The initial welding defects and constructional detail constitute the main factor of fatigue failure.The S-N curves for the joints were developed through a linear regession analysis of fatigue data.A formula for calculating constant amplitude fatigue,base on the concept of the hot spot stress amplitude,is proposed.展开更多
An improved list sphere decoder （ILSD） is proposed based on the conventional list sphere decoder （LSD） and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fix...An improved list sphere decoder （ILSD） is proposed based on the conventional list sphere decoder （LSD） and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.展开更多
基金The National Natural Science Foundation of China(No.51578357)the Natural Science Foundation of Shanxi Province(No.2015011062)Talent Training Program in the Postgraduate Joint Training Base of Shanxi Province(No.2016JD11)
文摘In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested under constant amplitude fatigue loads using a specially designed test rig.The joint was analyzed statically by t e finite element analysis(F3A),and metallographic analysis of fatigue fracture was done by the electron scanning microscope.Numerical simulation and experimental results show that the hot-spot of WCPHSJ lies at the weld toe location where severe stress is concentrated.Fatigue cracks initiate at the weld toe and then propagate circumferentially around the sphere with a diameter equivalent to the width of the cross plate up to the fatigue facture.The initial welding defects and constructional detail constitute the main factor of fatigue failure.The S-N curves for the joints were developed through a linear regession analysis of fatigue data.A formula for calculating constant amplitude fatigue,base on the concept of the hot spot stress amplitude,is proposed.
基金The National Natural Science Founda-tion of China ( No 60496316)the National Hi-Tech Re-search and Development Program (863) of China (No2006-AA01Z270)
文摘An improved list sphere decoder （ILSD） is proposed based on the conventional list sphere decoder （LSD） and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.
