In this paper,by constructing the current graph of the complete graph K_(12s+9)and a mapping function,we prove that K_(12s+9)(s is an odd number)has at least 6^(2s)×3^(s+3/2) nonisomorphic orientable quadrangular...In this paper,by constructing the current graph of the complete graph K_(12s+9)and a mapping function,we prove that K_(12s+9)(s is an odd number)has at least 6^(2s)×3^(s+3/2) nonisomorphic orientable quadrangular embeddings,and the orientable genus is(12s+9)(12s+4)/8+1.Every one of the nonisomorphic orientable quadrangular embeddings has at least twenty-four 4-edge-colors,and each color appears around each face of orientable quadrangular embeddings.展开更多
Though the preferred welding process to weld aluminium alloy is frequently constant current gas tungsten arc welding (CCGTAW),it resulted in grain coarsening at the fusion zone and heat affected zone(HAZ).Hence,pulsed...Though the preferred welding process to weld aluminium alloy is frequently constant current gas tungsten arc welding (CCGTAW),it resulted in grain coarsening at the fusion zone and heat affected zone(HAZ).Hence,pulsed current gas tungsten arc welding(PCGTAW) was performed,to yield finer fusion zone grains,which leads to higher strength of AA6061 (Al-Mg-Si) aluminium alloy joints.In order to determine the most influential control factors which will yield minimum fusion zone grain size and maximum tensile strength of the joints,the traditional Hooke and Jeeves pattern search method was used.The experiments were carried out based on central composite design with 31 runs and an algorithm was developed to optimize the fusion zone grain size and the tensile strength of pulsed current gas tungsten arc welded AA6061 aluminium alloy joints.The results indicate that the peak current (Ip) and base current (IB) are the most significant parameters,to decide the fusion zone grain size and the tensile strength of the AA6061 aluminum alloy joints.展开更多
文摘In this paper,by constructing the current graph of the complete graph K_(12s+9)and a mapping function,we prove that K_(12s+9)(s is an odd number)has at least 6^(2s)×3^(s+3/2) nonisomorphic orientable quadrangular embeddings,and the orientable genus is(12s+9)(12s+4)/8+1.Every one of the nonisomorphic orientable quadrangular embeddings has at least twenty-four 4-edge-colors,and each color appears around each face of orientable quadrangular embeddings.
基金Naval Research Board (NRB),Ministry of Defence,New Delhi for the financial support to carry out this investigation through sponsored project No.DNRD/05/4003/NRB/67.
文摘Though the preferred welding process to weld aluminium alloy is frequently constant current gas tungsten arc welding (CCGTAW),it resulted in grain coarsening at the fusion zone and heat affected zone(HAZ).Hence,pulsed current gas tungsten arc welding(PCGTAW) was performed,to yield finer fusion zone grains,which leads to higher strength of AA6061 (Al-Mg-Si) aluminium alloy joints.In order to determine the most influential control factors which will yield minimum fusion zone grain size and maximum tensile strength of the joints,the traditional Hooke and Jeeves pattern search method was used.The experiments were carried out based on central composite design with 31 runs and an algorithm was developed to optimize the fusion zone grain size and the tensile strength of pulsed current gas tungsten arc welded AA6061 aluminium alloy joints.The results indicate that the peak current (Ip) and base current (IB) are the most significant parameters,to decide the fusion zone grain size and the tensile strength of the AA6061 aluminum alloy joints.
