We prepared concretes(RC0, RC30, and RC100) with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method(MIM) and nuclear magnetic resonance(NMR...We prepared concretes(RC0, RC30, and RC100) with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method(MIM) and nuclear magnetic resonance(NMR) imaging. A capillary-bundle physical model with random-distribution pores(improved model, IM) was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental verifi cation.展开更多
The spatial and temporal distributions of acoustic emission (AE) during the deformation of samples containing an inhomogeneous fault have been studied under biaxial compression. The results show that the fault stren...The spatial and temporal distributions of acoustic emission (AE) during the deformation of samples containing an inhomogeneous fault have been studied under biaxial compression. The results show that the fault strength and the duration from loading to failure increase and the failure mode changes from abrupt instability to gradual failure with increase of lateral stress σ2. The pre-setting fault and its heterogeneity play an important role in controlling AE spatial distribution during the deformation. The basic pattern of AE spatial distribution is controlled by the pre-setting fault, especially the parts with inhomogeneous strength and the strong segment, and the localization of fracturing starts from the positions with inhomogeneous strength, With increase of σ5, the dense AE distribution area spreads from the positions with inhomogeneous strength to the whole strong segment gradually. AE temporal sequence is significantly affected by σ2. The fault shows abrupt instability in final failure, which occurs on a background of "enhancement-quiescence" in microfracturing activity at lower σ2. At higher σ5, the fault shows gradual failure, and AE occurrence rate increases continuously and AER increase exponentially before and after the failure, The effect of σ2 on b-value is also remarkable, b-value shows precursory decrease in the weakening stage when fault behavior is abrupt instability, but it shows balanced change when fault behavior is gradual failure,展开更多
One deformable mirror (DM) in conventional adaptive optics system can not meet the needs of large scale and high order aberration compensation. In this paper, a dual DMs way is presented, which needs the decoupling ...One deformable mirror (DM) in conventional adaptive optics system can not meet the needs of large scale and high order aberration compensation. In this paper, a dual DMs way is presented, which needs the decoupling of dual DMs. In dual DMs adaptive optics (AO) system, the decoupling algorithm of dual DMs is deduced. Stroke of one of DMs is large, spatial frequency of the other is high. According to the algorithm, the large stroke DM (LSDM) corrects low order aberration only, and the high spatial frequency DM (HSFDM) corrects other aberration. The experimental result for two 61-DM AO system is presented. The result indicates that the experimental performance of dual DMs AO system is almost the same with that of the conventional AO system using single DM with ideal stroke and equivalent spatial frequency.展开更多
基金Funded by the National Natural Science Foundation of China(51202304)the China Postdoctoral Science Foundation(2014M552320)+1 种基金Scientific,the Technological Talents’Special Funds of Wanzhou District and Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ1401016)the Youth Project of Chongqing Three Gorges College(13QN-20)
文摘We prepared concretes(RC0, RC30, and RC100) with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method(MIM) and nuclear magnetic resonance(NMR) imaging. A capillary-bundle physical model with random-distribution pores(improved model, IM) was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental verifi cation.
基金Joint Seismological Science Foundation of China (105076) and continued sub-project ″Statistic Features of After-shock Sequences and Forecast of the Large Aftershocks″ (2004BA601B01-04-02) managed by the Ministry of Science and Tech-nology of China in the 10th five-year plan.
文摘The spatial and temporal distributions of acoustic emission (AE) during the deformation of samples containing an inhomogeneous fault have been studied under biaxial compression. The results show that the fault strength and the duration from loading to failure increase and the failure mode changes from abrupt instability to gradual failure with increase of lateral stress σ2. The pre-setting fault and its heterogeneity play an important role in controlling AE spatial distribution during the deformation. The basic pattern of AE spatial distribution is controlled by the pre-setting fault, especially the parts with inhomogeneous strength and the strong segment, and the localization of fracturing starts from the positions with inhomogeneous strength, With increase of σ5, the dense AE distribution area spreads from the positions with inhomogeneous strength to the whole strong segment gradually. AE temporal sequence is significantly affected by σ2. The fault shows abrupt instability in final failure, which occurs on a background of "enhancement-quiescence" in microfracturing activity at lower σ2. At higher σ5, the fault shows gradual failure, and AE occurrence rate increases continuously and AER increase exponentially before and after the failure, The effect of σ2 on b-value is also remarkable, b-value shows precursory decrease in the weakening stage when fault behavior is abrupt instability, but it shows balanced change when fault behavior is gradual failure,
基金supported by the 863 Program under Grant No 2005AA823060
文摘One deformable mirror (DM) in conventional adaptive optics system can not meet the needs of large scale and high order aberration compensation. In this paper, a dual DMs way is presented, which needs the decoupling of dual DMs. In dual DMs adaptive optics (AO) system, the decoupling algorithm of dual DMs is deduced. Stroke of one of DMs is large, spatial frequency of the other is high. According to the algorithm, the large stroke DM (LSDM) corrects low order aberration only, and the high spatial frequency DM (HSFDM) corrects other aberration. The experimental result for two 61-DM AO system is presented. The result indicates that the experimental performance of dual DMs AO system is almost the same with that of the conventional AO system using single DM with ideal stroke and equivalent spatial frequency.