Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undes...Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undesired by-products, leading to higher purification costs. This paper gives an extensive review and analysis of micro-mixing studies in single- and multi phase stirred tanks. The relevant experiment techniques, micro-mixing models and nurherical approaches are critically reviewed and analyzed with remarks and perspectives. The reported studies on two-phase micro-mixing experiments and on the impact of the presence of the dispersed phases on turbulence have been limited to a narrow range of conditions. More importantly, disparities widely exist among different reports. Both Lagrangian and Eulerian models are based on oversimplified assumptions, which may lead to uncertainties or even unrealistic results. A heuristic model, which is from the perspective of CFD （computational fluid dynamics） and can cover the whole spectrum of scales and also focus on every subrocess, is desired in the future.展开更多
Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical mu...Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields.展开更多
Meaning of the concept of＂makom＂ is hard to define with some frames and borders. Thus, German researcher Yu. Elzner provided more than 20 meanings of this word translated from Arabic. Music experts have decided in f...Meaning of the concept of＂makom＂ is hard to define with some frames and borders. Thus, German researcher Yu. Elzner provided more than 20 meanings of this word translated from Arabic. Music experts have decided in favor of the definition of word makom as ＂mode and genre＂. Establishment of makom as a genre had taken place approximately from 12th to 18th centuries. However, evolution of a mode system, had occurred much earlier. Makom art of Uzbekistan is a heritage, which had been formed over the long period. However, it has not yet reached its completion, it still keeps living and being filled with a new emotional mood, new image contents. Swift development of computer technology and communication means creates opportunities both for researchers and for performers to improve the phenomenon of the makom arts. Organization of various contests and festivals in Uzbekistan, makom performers＇ participation in foreign forums represents great incentives for showing the western interest in this arts and its integration into the global music science.展开更多
To overcome the shortcomings that there are few feasible methods and models in the comprehensive assessment on the system reliability of cable-stayed bridges, a mathematical tool-the unascertalned measure was introduc...To overcome the shortcomings that there are few feasible methods and models in the comprehensive assessment on the system reliability of cable-stayed bridges, a mathematical tool-the unascertalned measure was introduced. First, the basic knowledge of the Unascertained Sets was introduced briefly. Second, the unascertained measure was defined and the comprehensive assessment model was set up. Then the method was introduced to the assessment of the system reliability of a cable-stayed bridge located in Tianjin City. Engineering practices shows that the method can complete the assessment systematically and scientifically without any assumption. The work has significance in theory and practice for the comprehensive assessment of bridge engineering.展开更多
The most relevant aspects related to the phase mask dithering/moving method for the fabrication of complex Bragg grating designs are reviewed. Details for experimental implementation of this technique is presented, in...The most relevant aspects related to the phase mask dithering/moving method for the fabrication of complex Bragg grating designs are reviewed. Details for experimental implementation of this technique is presented, including theoretical analysis of the calibration functions for the correct dither/displacement. Results from tailored Bragg grating structures fabricated by this method are shown. Apodized Bragg gratings with modeled spatial profiles were implemented, resulting in side mode suppression levels of more than 20 dB in gratings showing transmission filtering level higher than 30 dB. Chirped gratings with the spectral bandwidth up to 4 nm, π-shift and sampled Bragg gratings with equalized peaks equally spaced by 0.8 nm （100 GHz） were also fabricated.展开更多
基金Supported by the State Key Development Program for Basic Research of China (2010CB630904)the National Natural Science Fund for Distinguished Young Scholars (21025627)+2 种基金the National Natural Science Foundation of China (21106154,20990224)the National High Technology Research and Development Program of China (2011AA060704)the Beijing Natural Science Foundation (2112038) and Jiangsu Province Project (BY2009133)
文摘Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects. Micro-mixing is an important aspect for fast or quasi-instantaneous reactions. Poor micro-mixing might produce more undesired by-products, leading to higher purification costs. This paper gives an extensive review and analysis of micro-mixing studies in single- and multi phase stirred tanks. The relevant experiment techniques, micro-mixing models and nurherical approaches are critically reviewed and analyzed with remarks and perspectives. The reported studies on two-phase micro-mixing experiments and on the impact of the presence of the dispersed phases on turbulence have been limited to a narrow range of conditions. More importantly, disparities widely exist among different reports. Both Lagrangian and Eulerian models are based on oversimplified assumptions, which may lead to uncertainties or even unrealistic results. A heuristic model, which is from the perspective of CFD （computational fluid dynamics） and can cover the whole spectrum of scales and also focus on every subrocess, is desired in the future.
基金the National Natural Science Foundation of China under，教育部科学技术研究项目
文摘Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields.
文摘Meaning of the concept of＂makom＂ is hard to define with some frames and borders. Thus, German researcher Yu. Elzner provided more than 20 meanings of this word translated from Arabic. Music experts have decided in favor of the definition of word makom as ＂mode and genre＂. Establishment of makom as a genre had taken place approximately from 12th to 18th centuries. However, evolution of a mode system, had occurred much earlier. Makom art of Uzbekistan is a heritage, which had been formed over the long period. However, it has not yet reached its completion, it still keeps living and being filled with a new emotional mood, new image contents. Swift development of computer technology and communication means creates opportunities both for researchers and for performers to improve the phenomenon of the makom arts. Organization of various contests and festivals in Uzbekistan, makom performers＇ participation in foreign forums represents great incentives for showing the western interest in this arts and its integration into the global music science.
文摘To overcome the shortcomings that there are few feasible methods and models in the comprehensive assessment on the system reliability of cable-stayed bridges, a mathematical tool-the unascertalned measure was introduced. First, the basic knowledge of the Unascertained Sets was introduced briefly. Second, the unascertained measure was defined and the comprehensive assessment model was set up. Then the method was introduced to the assessment of the system reliability of a cable-stayed bridge located in Tianjin City. Engineering practices shows that the method can complete the assessment systematically and scientifically without any assumption. The work has significance in theory and practice for the comprehensive assessment of bridge engineering.
文摘The most relevant aspects related to the phase mask dithering/moving method for the fabrication of complex Bragg grating designs are reviewed. Details for experimental implementation of this technique is presented, including theoretical analysis of the calibration functions for the correct dither/displacement. Results from tailored Bragg grating structures fabricated by this method are shown. Apodized Bragg gratings with modeled spatial profiles were implemented, resulting in side mode suppression levels of more than 20 dB in gratings showing transmission filtering level higher than 30 dB. Chirped gratings with the spectral bandwidth up to 4 nm, π-shift and sampled Bragg gratings with equalized peaks equally spaced by 0.8 nm （100 GHz） were also fabricated.
