An analysis was conducted on the evolutional process of a mesoscale convective vortex (MCV) and associated heavy rainfall in the Dabie Mountain area on 21-22 June 2008,as well as their structural characteristics in ...An analysis was conducted on the evolutional process of a mesoscale convective vortex (MCV) and associated heavy rainfall in the Dabie Mountain area on 21-22 June 2008,as well as their structural characteristics in different stages,by using the mesoscale reanalysis data with 3 km and 1 h resolution generated by the Local Analysis and Prediction System (LAPS) in the Southern China Heavy Rainfall Experiment.The results showed that the latent heat released by convection in the midtroposphere was the main energy source for the development of a low-level vortex.There was a positive feedback interaction between the convection and the vortex,and the evolution of the MCV was closely related to the strength of the positive interaction.The most typical characteristics of the thermal structure in different stages were that,there was a relatively thin diabatic heating layer in the midtroposphere in the formative stage;the thickness of diabatic heating layer significantly increased in the mature stage;and it almost disappeared in the decay stage.The characteristics of the dynamic structure were that,in the formative stage,there was no anticyclonic circulation at the high level;in the mature stage,an anticyclonic circulation with strong divergence was formed at the high level;in the decay stage,the anticyclonic circulation was damaged and the high-level atmosphere was in a disordered state of turbulence.Finally,the structural schematics of the MCV in the formative and mature stage were established respectively.展开更多
Schema theory originated from western Countries.It explained explicitly how readers' world knowledge interacts with text to arrive at comprehension.Many Chinese English teachers use it to guide their teaching,but ...Schema theory originated from western Countries.It explained explicitly how readers' world knowledge interacts with text to arrive at comprehension.Many Chinese English teachers use it to guide their teaching,but most of them can not get an ideal outcome.First,this paper represent schemata and schematic theory briefly,and then explores the interactions beween schematic theory and reading comprehension.At last,the author lists out three factors that is helpful for comprehending and establishing new schemata.展开更多
Flexible transfer line(FTL)is now widely used in ma ny manufacturing domains to realize efficiently,high quantity and economic prod uction.These manufacturing domains include automobile,tractor,internal-combu stion en...Flexible transfer line(FTL)is now widely used in ma ny manufacturing domains to realize efficiently,high quantity and economic prod uction.These manufacturing domains include automobile,tractor,internal-combu stion engine,and so on.In today’s competitive business environment,it is vit ally important for machine tool manufacturers to design flexible transfer line m ore effectively and efficiently according to a wider variety of customer demand s.This paper proposes an approach to a bidding-based flexible transfer line sc hematic design system.By analyzing manual FTL design process,the architecture o f flexible transfer line schematic design system(FTLSDS)is established.The syst em consists:of four processes:part feature modeling,process planning,FTL fac i lity layout and FTL evaluation. For FTL schematic design.a five-level proces s planning strategy named hierarchical process planning method is proposed.This method includes selection of manufacturing feature machining operation;part se t-up planning,feature sequencing,operation sequencing and process plan genera ting.The major decision relies on setup planning.According to the proceeding o f the hierarchical process planning,the structure of reasoning is proposed base d on blackboard.Under this paradigm,a cooperative effort between a hybrid coll ection of knowledge sources is possible.Total reasoning task can be divided int o some subtasks,and recursive-reasoning system is formed.It is convenient for process planning with step-by-step solution.Meanwhile,the blackboard is use d as the global data exchange area during all reasoning process.By using modula r technology,special purpose machine tools can be designed more efficiently and rapidly.The framework of machine modular design system to support machine requ irement design for FTL is established.By synthesizing the FTL evaluation criter ia.five evaluation criteria of flexible transfer 1ine schematic design are take n into account.An exampie is supplied to demonstrate and verify the validity an d feasibility of flexible transfer line schematic design approach.展开更多
When water penetrates into soil,interstitial air can become trapped by the infiltrating water.Neglecting the effect of air ventilation could cause deviations in the predicted pore water pressure and the associated eff...When water penetrates into soil,interstitial air can become trapped by the infiltrating water.Neglecting the effect of air ventilation could cause deviations in the predicted pore water pressure and the associated effective stress.This study aims at the effect of air ventilation on the coupled hydro-mechanical responses in homogeneous soil during infiltration.A schematic concept of infiltration conditions(open-and closed-valve)in homogeneous soil is proposed for investigating their impacts on the pore water pressure and effective stress.Experiments of vertical soil column filled with Ottawa sand(ASTM C77820/30)were designed for two types of air ventilation(namely,open and closed infiltration).The evolution of pore water pressure at the cylinder bottom was recorded,and served as a benchmark problem for evaluating the coupled hydro-mechanical response.Coding with the commercial software,GeoStudio,was employed for the dynamic behaviors of pore-water and-air pressures as well as the evolving effective stress.It was found in both the experiments and numerical investigations that the infiltration condition plays a crucial role for the ascending rate of pore water pressure as well as the associated effective stress.These results illustrate the inevitable impacts of the air ventilation conditions on the mechanical properties of the soil during infiltration.展开更多
The high speed and precision 16 bits DAC will be applied in DSP (Digital Signal Processing) based on CSR pulsed power supply control system. In this application the DAC is needed to work in 1 μs’ converting data rat...The high speed and precision 16 bits DAC will be applied in DSP (Digital Signal Processing) based on CSR pulsed power supply control system. In this application the DAC is needed to work in 1 μs’ converting data rate, 16 bit resolution and its output voltage is 10 volts.展开更多
The fundamental transverse mode(TEM00)is preferable for experimental and theoretical study on the laser-induced retinal injury effect,for it can produce the minimal retinal image andestablish the most strict laser saf...The fundamental transverse mode(TEM00)is preferable for experimental and theoretical study on the laser-induced retinal injury effect,for it can produce the minimal retinal image andestablish the most strict laser safety standards.But actually lasers with higher order mode werefrequently used in both earlier and recent studies.Generally higher order mode leads to largerretinal spot size and so higher damage threshold,but there are few quantitative analyses on thisproblem.In this paper,a four-surface schematic eye model is established for human and macaque.The propagation of 532-nm laser in schematic eye is analyzed by the ABCD law of Gaussianoptics.It is shown that retinal spot size increases with laser transverse mode order.For relativelower mode order,the retinal spot diameter will not exceed the minimum laser-induced retinallesion(25~30μm in diameter),and so has little effect on retinal damage threshold.While forhigher order mode,the larger'retinal spot requires more energy to induce injury and so the damage threshold increases.When beam divergence is lowered,the retinal spot size decreasescorrespondingly,so the efect of mode order can be compensated.The retinal spot size of macaqueis slightly smaller than that of human and the ratio bet ween them is independent of mode order.We conclude that the laser mode order has significant influence on retinal spot size but limitedinfluence on the retinal injury ffect.展开更多
Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffract...Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.展开更多
In this Letter, we demonstrate a diode-pumped electro-optical cavity-dumped Tm:YAP laser for the first time to our knowledge. A pulse width of 7.1 ns is achieved at a wavelength of 1996.9 nm. A maximum output power o...In this Letter, we demonstrate a diode-pumped electro-optical cavity-dumped Tm:YAP laser for the first time to our knowledge. A pulse width of 7.1 ns is achieved at a wavelength of 1996.9 nm. A maximum output power of 3.02 W is obtained with a pump power of 58.8 W at a repetition rate of 100 k Hz and a high-voltage time of 1000 ns, corresponding to an overall optical-to-optical conversion efficiency of 5.2%. In addition, we study the effect of repetition rate and high-voltage time on the output power characteristics of a cavity-dumped Tm:YAP laser.展开更多
The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function...The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function of grating period, filling factor, and groove depth, and the antireflective characteristics are also studied when visible-infrared light is incident upon them. Numerical examples are given for gratings on glass substrate with refractive index of 1.5. The results show that this kind of grating is capable of reducing reflections, and could achieve very low reflectivity over a wide field of view and a wide waveband by choosing appropriate parameters.展开更多
With the support from the National Natural Science Foundation of China,the National Basic Research Program of China,and the Science&Technology Commission of Shanghai Municipality,the research teamled by Prof.Li Xi...With the support from the National Natural Science Foundation of China,the National Basic Research Program of China,and the Science&Technology Commission of Shanghai Municipality,the research teamled by Prof.Li Xiaotao(李晓涛)at the Shanghai Key Laboratory of Regulatory Biology,Institute of Biomedical Sciences,East China Normal University collaborated with Prof.Xiao Jianru at展开更多
基金supported by the state "973" project "Research on Theories and Methods of Monitoring and Predicting of Heavy Rainfall in South China" (Grant No. 2004CB418300)
文摘An analysis was conducted on the evolutional process of a mesoscale convective vortex (MCV) and associated heavy rainfall in the Dabie Mountain area on 21-22 June 2008,as well as their structural characteristics in different stages,by using the mesoscale reanalysis data with 3 km and 1 h resolution generated by the Local Analysis and Prediction System (LAPS) in the Southern China Heavy Rainfall Experiment.The results showed that the latent heat released by convection in the midtroposphere was the main energy source for the development of a low-level vortex.There was a positive feedback interaction between the convection and the vortex,and the evolution of the MCV was closely related to the strength of the positive interaction.The most typical characteristics of the thermal structure in different stages were that,there was a relatively thin diabatic heating layer in the midtroposphere in the formative stage;the thickness of diabatic heating layer significantly increased in the mature stage;and it almost disappeared in the decay stage.The characteristics of the dynamic structure were that,in the formative stage,there was no anticyclonic circulation at the high level;in the mature stage,an anticyclonic circulation with strong divergence was formed at the high level;in the decay stage,the anticyclonic circulation was damaged and the high-level atmosphere was in a disordered state of turbulence.Finally,the structural schematics of the MCV in the formative and mature stage were established respectively.
文摘Schema theory originated from western Countries.It explained explicitly how readers' world knowledge interacts with text to arrive at comprehension.Many Chinese English teachers use it to guide their teaching,but most of them can not get an ideal outcome.First,this paper represent schemata and schematic theory briefly,and then explores the interactions beween schematic theory and reading comprehension.At last,the author lists out three factors that is helpful for comprehending and establishing new schemata.
文摘Flexible transfer line(FTL)is now widely used in ma ny manufacturing domains to realize efficiently,high quantity and economic prod uction.These manufacturing domains include automobile,tractor,internal-combu stion engine,and so on.In today’s competitive business environment,it is vit ally important for machine tool manufacturers to design flexible transfer line m ore effectively and efficiently according to a wider variety of customer demand s.This paper proposes an approach to a bidding-based flexible transfer line sc hematic design system.By analyzing manual FTL design process,the architecture o f flexible transfer line schematic design system(FTLSDS)is established.The syst em consists:of four processes:part feature modeling,process planning,FTL fac i lity layout and FTL evaluation. For FTL schematic design.a five-level proces s planning strategy named hierarchical process planning method is proposed.This method includes selection of manufacturing feature machining operation;part se t-up planning,feature sequencing,operation sequencing and process plan genera ting.The major decision relies on setup planning.According to the proceeding o f the hierarchical process planning,the structure of reasoning is proposed base d on blackboard.Under this paradigm,a cooperative effort between a hybrid coll ection of knowledge sources is possible.Total reasoning task can be divided int o some subtasks,and recursive-reasoning system is formed.It is convenient for process planning with step-by-step solution.Meanwhile,the blackboard is use d as the global data exchange area during all reasoning process.By using modula r technology,special purpose machine tools can be designed more efficiently and rapidly.The framework of machine modular design system to support machine requ irement design for FTL is established.By synthesizing the FTL evaluation criter ia.five evaluation criteria of flexible transfer 1ine schematic design are take n into account.An exampie is supplied to demonstrate and verify the validity an d feasibility of flexible transfer line schematic design approach.
文摘When water penetrates into soil,interstitial air can become trapped by the infiltrating water.Neglecting the effect of air ventilation could cause deviations in the predicted pore water pressure and the associated effective stress.This study aims at the effect of air ventilation on the coupled hydro-mechanical responses in homogeneous soil during infiltration.A schematic concept of infiltration conditions(open-and closed-valve)in homogeneous soil is proposed for investigating their impacts on the pore water pressure and effective stress.Experiments of vertical soil column filled with Ottawa sand(ASTM C77820/30)were designed for two types of air ventilation(namely,open and closed infiltration).The evolution of pore water pressure at the cylinder bottom was recorded,and served as a benchmark problem for evaluating the coupled hydro-mechanical response.Coding with the commercial software,GeoStudio,was employed for the dynamic behaviors of pore-water and-air pressures as well as the evolving effective stress.It was found in both the experiments and numerical investigations that the infiltration condition plays a crucial role for the ascending rate of pore water pressure as well as the associated effective stress.These results illustrate the inevitable impacts of the air ventilation conditions on the mechanical properties of the soil during infiltration.
文摘The high speed and precision 16 bits DAC will be applied in DSP (Digital Signal Processing) based on CSR pulsed power supply control system. In this application the DAC is needed to work in 1 μs’ converting data rate, 16 bit resolution and its output voltage is 10 volts.
基金the support from the National Nature Science Foundation of China(NSFC),the grant number is 61275194.
文摘The fundamental transverse mode(TEM00)is preferable for experimental and theoretical study on the laser-induced retinal injury effect,for it can produce the minimal retinal image andestablish the most strict laser safety standards.But actually lasers with higher order mode werefrequently used in both earlier and recent studies.Generally higher order mode leads to largerretinal spot size and so higher damage threshold,but there are few quantitative analyses on thisproblem.In this paper,a four-surface schematic eye model is established for human and macaque.The propagation of 532-nm laser in schematic eye is analyzed by the ABCD law of Gaussianoptics.It is shown that retinal spot size increases with laser transverse mode order.For relativelower mode order,the retinal spot diameter will not exceed the minimum laser-induced retinallesion(25~30μm in diameter),and so has little effect on retinal damage threshold.While forhigher order mode,the larger'retinal spot requires more energy to induce injury and so the damage threshold increases.When beam divergence is lowered,the retinal spot size decreasescorrespondingly,so the efect of mode order can be compensated.The retinal spot size of macaqueis slightly smaller than that of human and the ratio bet ween them is independent of mode order.We conclude that the laser mode order has significant influence on retinal spot size but limitedinfluence on the retinal injury ffect.
文摘Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.
基金supported by the National Natural Science Foundation of China (Nos. 61308009 and 61405047)the China Postdoctoral Science Foundation funded project (Nos. 2013M540288 and 2015M570290)+2 种基金the Fundamental Research funds for the Central Universities Grant (Nos. HIT. NSRIF.2014044 and HIT. NSRIF.2015042)the Science Fund for Outstanding Youths of Heilongjiang Province (No. JQ201310)the Heilongjiang Postdoctoral Science Foundation Funded Project (No. LBH-Z14085)
文摘In this Letter, we demonstrate a diode-pumped electro-optical cavity-dumped Tm:YAP laser for the first time to our knowledge. A pulse width of 7.1 ns is achieved at a wavelength of 1996.9 nm. A maximum output power of 3.02 W is obtained with a pump power of 58.8 W at a repetition rate of 100 k Hz and a high-voltage time of 1000 ns, corresponding to an overall optical-to-optical conversion efficiency of 5.2%. In addition, we study the effect of repetition rate and high-voltage time on the output power characteristics of a cavity-dumped Tm:YAP laser.
文摘The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function of grating period, filling factor, and groove depth, and the antireflective characteristics are also studied when visible-infrared light is incident upon them. Numerical examples are given for gratings on glass substrate with refractive index of 1.5. The results show that this kind of grating is capable of reducing reflections, and could achieve very low reflectivity over a wide field of view and a wide waveband by choosing appropriate parameters.
文摘With the support from the National Natural Science Foundation of China,the National Basic Research Program of China,and the Science&Technology Commission of Shanghai Municipality,the research teamled by Prof.Li Xiaotao(李晓涛)at the Shanghai Key Laboratory of Regulatory Biology,Institute of Biomedical Sciences,East China Normal University collaborated with Prof.Xiao Jianru at