A high speed data sampling system on dynamic Oscillographic analysis was established with a 80386DX40 computer, AD 674 and flow injection system. Programs were designed in Microsoft Windows 3.1, that can process E-t, ...A high speed data sampling system on dynamic Oscillographic analysis was established with a 80386DX40 computer, AD 674 and flow injection system. Programs were designed in Microsoft Windows 3.1, that can process E-t, dE/dt-t, i'(f)-t and other kinds of curve on oscillographic analysis. A satisfactory result on determination of Pb2+ and Cd2+ was obtained.展开更多
Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage a...Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage and multiple impact damage of C/SiC composites is limited.To investigate the in-plane impact damage behavior of C/SiC composites,a drop-weight impact test method was developed for strip samples,and these results were subsequently compared with those of C/SiC composite plates.Results show that the in-plane impact behavior of C/SiC strip samples is similar to that of C/SiC composite plates.Variation of the impact load with displacement is characterized by three stages:a nearly linear stage,a severe load drop stage,and a rebound stage where displacement occurs after the impact energy exceeds its peak value.Impact damage behavior under single and multiple impacts on 2D plain and 3D needled C/SiC composites was investigated at different impact energies and durations.Crack propagation in C/SiC composites was studied by computerized tomography(CT)technique.In the 2D plain C/SiC composite,load propagation between layers is hindered during impact,leading to delamination and 90°fiber brittle fracture.The crack length perpendicular to the impact direction increases with impact energy increases,resulting in more serious 0°fiber fracture and a larger area of fiber loss.In the 3D needled C/SiC composite,load propagates between the layers during impact through the connection of needled fibers.The fibers continue to provide substantial structural support,with notable instances of fiber pull-off and debonding.Consequently,the impact resistance is superior to that of 2D plain C/SiC composite.When the 3D needled C/SiC composite undergoes two successive impacts of 1.5 J,the energy absorption efficiency of the second impact is significantly lower,accompanied by a smaller impact displacement.Moreover,the total energy absorption efficiency of these two impacts of 1.5 J is lower than that of a single 3.0 J impact.展开更多
The present study aimed to investigate the application of the CLAN(Computerized Language Analysis)program in the CHILDES(Child Language Data Exchange System)on shared and unique words between storybooks.Sixty sixth-gr...The present study aimed to investigate the application of the CLAN(Computerized Language Analysis)program in the CHILDES(Child Language Data Exchange System)on shared and unique words between storybooks.Sixty sixth-grade Chinese-speaking children at an elementary school in Taipei City were recruited.Forty-four three-level of storybooks from Kizclub were collected and analyzed.Fifteen minutes reading instruction was followed by the use of CLAN on storybooks for 25 minutes.Children were given written and spoken vocabulary tests after each cluster of storybook reading period.There were three main findings of the study.First,young EFL(English as a Foreign Language)learners'word learning was enhanced through multiple exposures to the shared and unique words from the storybooks.Second,word instruction in isolation prompted written and spoken word learning beyond word instruction in context and repeated reading.Third,the results had pedagogical implications on the value and feasibility of language teaching with storybooks in promoting EFL students'word learning by using CLAN,and the limitations of the study were provided.展开更多
文摘A high speed data sampling system on dynamic Oscillographic analysis was established with a 80386DX40 computer, AD 674 and flow injection system. Programs were designed in Microsoft Windows 3.1, that can process E-t, dE/dt-t, i'(f)-t and other kinds of curve on oscillographic analysis. A satisfactory result on determination of Pb2+ and Cd2+ was obtained.
基金Aeronautical Science Foundation of China(2021Z057053001)。
文摘Continuous carbon fiber reinforced silicon carbide(C/SiC)composites are often subjected to low-velocity impacts when utilized as structural materials for thermal protection.However,research on in-plane impact damage and multiple impact damage of C/SiC composites is limited.To investigate the in-plane impact damage behavior of C/SiC composites,a drop-weight impact test method was developed for strip samples,and these results were subsequently compared with those of C/SiC composite plates.Results show that the in-plane impact behavior of C/SiC strip samples is similar to that of C/SiC composite plates.Variation of the impact load with displacement is characterized by three stages:a nearly linear stage,a severe load drop stage,and a rebound stage where displacement occurs after the impact energy exceeds its peak value.Impact damage behavior under single and multiple impacts on 2D plain and 3D needled C/SiC composites was investigated at different impact energies and durations.Crack propagation in C/SiC composites was studied by computerized tomography(CT)technique.In the 2D plain C/SiC composite,load propagation between layers is hindered during impact,leading to delamination and 90°fiber brittle fracture.The crack length perpendicular to the impact direction increases with impact energy increases,resulting in more serious 0°fiber fracture and a larger area of fiber loss.In the 3D needled C/SiC composite,load propagates between the layers during impact through the connection of needled fibers.The fibers continue to provide substantial structural support,with notable instances of fiber pull-off and debonding.Consequently,the impact resistance is superior to that of 2D plain C/SiC composite.When the 3D needled C/SiC composite undergoes two successive impacts of 1.5 J,the energy absorption efficiency of the second impact is significantly lower,accompanied by a smaller impact displacement.Moreover,the total energy absorption efficiency of these two impacts of 1.5 J is lower than that of a single 3.0 J impact.
文摘The present study aimed to investigate the application of the CLAN(Computerized Language Analysis)program in the CHILDES(Child Language Data Exchange System)on shared and unique words between storybooks.Sixty sixth-grade Chinese-speaking children at an elementary school in Taipei City were recruited.Forty-four three-level of storybooks from Kizclub were collected and analyzed.Fifteen minutes reading instruction was followed by the use of CLAN on storybooks for 25 minutes.Children were given written and spoken vocabulary tests after each cluster of storybook reading period.There were three main findings of the study.First,young EFL(English as a Foreign Language)learners'word learning was enhanced through multiple exposures to the shared and unique words from the storybooks.Second,word instruction in isolation prompted written and spoken word learning beyond word instruction in context and repeated reading.Third,the results had pedagogical implications on the value and feasibility of language teaching with storybooks in promoting EFL students'word learning by using CLAN,and the limitations of the study were provided.
