We investigate redshift distributions of three long burst samples, with the first sample containing 131 long bursts with observed redshifts, the second including 220 long bursts with pseudo-redshifts calculated by the...We investigate redshift distributions of three long burst samples, with the first sample containing 131 long bursts with observed redshifts, the second including 220 long bursts with pseudo-redshifts calculated by the variability-luminosity relation, and the third including 1194 long bursts with pseudo-redshifls calculated by the lag-luminosity relation, respectively. In the redshift range 0-1 the Kolmogorov-Smirnov probability of the observed redshift distribution and that of the variability-luminosity relation is large. In the redshift ranges 1-2, 2-3, 3-6.3 and 0-37, the Kolmogorov-Smirnov probabilities of the redshift distribution from lag-luminosity relation and the observed redshift distribution are also large. For the GRBs, which appear both in the two pseudo-redshift burst samples, the KS probability of the pseudo-redshift distribution from the lag-luminosity relation and the observed reshift distribution is 0.447, which is very large. Based on these results, some conclusions are drawn： i） the V-Liso relation might be more believable than the τ-Liso relation in low redshift ranges and the τ-Liso relation might be more real than the V-Liso relation in high redshift ranges; ii） if we do not consider the redshift ranges, the τ-Liso relation might be more physical and intrinsical than the V-Liso relation.展开更多
Researches on ultra-high performance concrete (UHPC) have been conducted worldwide owing to its outstanding durability and strength performances. The exploitation of the mechanical properties of UHPC will render it po...Researches on ultra-high performance concrete (UHPC) have been conducted worldwide owing to its outstanding durability and strength performances. The exploitation of the mechanical properties of UHPC will render it possible to achieve economic design through substantial reduction in the cross sectional dimensions and simplification in the reinforcement arrangement. This paper investigates experimentally the load transfer in the prestressed concrete anchorage zone. To provide distinctive features of UHPC compared to ordinary concrete, the cross sectional dimensions of the member were reduced and the stress distribution, deformation and cracking pattern of the PS anchorage zone were examined experimentally according to the degree of reinforcement of the members chosen. The distributions of the bursting stress, spalling stress and longitudinal edge stress in the specimens were observed according to the various types of reinforcement. All the specimens satisfied the load-bearing capacity criterion specified by the European ETAG-013 guidelines and their stress distributions were similar to those in the PS anchorages of post-tensioned members applying ordinary concrete. The cracks propagated longitudinally with lengths up to twice the cross sectional dimensions and their width was smaller than when applying ordinary concrete owing to the bridging effect of the steel fibers in UHPC. Accordingly, the exploitation of the high strength of UHPC enabled us to secure the resistance of the anchorage with no need for particular reinforcing devices.展开更多
非金属壳体在同等压力下的变形量远大于钢制壳体,使用针对钢制容器的普通水压试验装备和方法无法满足非金属壳体的水压检测工作,为此研发出一种适用于非金属大变形壳体的水压爆破试验工艺与装备,并进行了试样壳体水压试验、水压爆破试验...非金属壳体在同等压力下的变形量远大于钢制壳体,使用针对钢制容器的普通水压试验装备和方法无法满足非金属壳体的水压检测工作,为此研发出一种适用于非金属大变形壳体的水压爆破试验工艺与装备,并进行了试样壳体水压试验、水压爆破试验,均一次性测试成功。测试和使用结果表明:该工艺和装备能够满足容积范围0.005~15 m 3、压力范围0~150 MPa的非金属壳体的水压试验与水压爆破试验,试压精度可达±0.1 MPa。试压产品规格范围广,增压速度快,压力精度高,压力曲线均匀稳定,试验数据精确可靠,能保证按照多级试压梯度一次性完成水压试验与水压爆破试验。独有的增压系统和试压工艺可有效避免因为增压速度慢、压力曲线波动、单方面数据检测误差等因素而误判产品不合格,保证了试压壳体的检测质量,节约了重复试压的经济成本和试压壳体的制造成本。投产后实际使用效果显著,对提升我国非金属壳体水压试验工艺水平有重大参考意义。展开更多
基金supported by the National Natural Science Foundation of China(NSFC, No. 10473023)Scientific Research Fund of the Sichuan Provincial Education Department,the K. C. Wong Education Foundation (Hong Kong)the Jiangsu Planned Projects for PostdoctoralResearch Funds.
文摘We investigate redshift distributions of three long burst samples, with the first sample containing 131 long bursts with observed redshifts, the second including 220 long bursts with pseudo-redshifts calculated by the variability-luminosity relation, and the third including 1194 long bursts with pseudo-redshifls calculated by the lag-luminosity relation, respectively. In the redshift range 0-1 the Kolmogorov-Smirnov probability of the observed redshift distribution and that of the variability-luminosity relation is large. In the redshift ranges 1-2, 2-3, 3-6.3 and 0-37, the Kolmogorov-Smirnov probabilities of the redshift distribution from lag-luminosity relation and the observed redshift distribution are also large. For the GRBs, which appear both in the two pseudo-redshift burst samples, the KS probability of the pseudo-redshift distribution from the lag-luminosity relation and the observed reshift distribution is 0.447, which is very large. Based on these results, some conclusions are drawn： i） the V-Liso relation might be more believable than the τ-Liso relation in low redshift ranges and the τ-Liso relation might be more real than the V-Liso relation in high redshift ranges; ii） if we do not consider the redshift ranges, the τ-Liso relation might be more physical and intrinsical than the V-Liso relation.
文摘Researches on ultra-high performance concrete (UHPC) have been conducted worldwide owing to its outstanding durability and strength performances. The exploitation of the mechanical properties of UHPC will render it possible to achieve economic design through substantial reduction in the cross sectional dimensions and simplification in the reinforcement arrangement. This paper investigates experimentally the load transfer in the prestressed concrete anchorage zone. To provide distinctive features of UHPC compared to ordinary concrete, the cross sectional dimensions of the member were reduced and the stress distribution, deformation and cracking pattern of the PS anchorage zone were examined experimentally according to the degree of reinforcement of the members chosen. The distributions of the bursting stress, spalling stress and longitudinal edge stress in the specimens were observed according to the various types of reinforcement. All the specimens satisfied the load-bearing capacity criterion specified by the European ETAG-013 guidelines and their stress distributions were similar to those in the PS anchorages of post-tensioned members applying ordinary concrete. The cracks propagated longitudinally with lengths up to twice the cross sectional dimensions and their width was smaller than when applying ordinary concrete owing to the bridging effect of the steel fibers in UHPC. Accordingly, the exploitation of the high strength of UHPC enabled us to secure the resistance of the anchorage with no need for particular reinforcing devices.
文摘非金属壳体在同等压力下的变形量远大于钢制壳体,使用针对钢制容器的普通水压试验装备和方法无法满足非金属壳体的水压检测工作,为此研发出一种适用于非金属大变形壳体的水压爆破试验工艺与装备,并进行了试样壳体水压试验、水压爆破试验,均一次性测试成功。测试和使用结果表明:该工艺和装备能够满足容积范围0.005~15 m 3、压力范围0~150 MPa的非金属壳体的水压试验与水压爆破试验,试压精度可达±0.1 MPa。试压产品规格范围广,增压速度快,压力精度高,压力曲线均匀稳定,试验数据精确可靠,能保证按照多级试压梯度一次性完成水压试验与水压爆破试验。独有的增压系统和试压工艺可有效避免因为增压速度慢、压力曲线波动、单方面数据检测误差等因素而误判产品不合格,保证了试压壳体的检测质量,节约了重复试压的经济成本和试压壳体的制造成本。投产后实际使用效果显著,对提升我国非金属壳体水压试验工艺水平有重大参考意义。
