The roles of recasts have been intensively studied in the first language (L1) research. This essay explores the role of recasts in second language acquisition, mainly focusing on discussing the studies addressing the ...The roles of recasts have been intensively studied in the first language (L1) research. This essay explores the role of recasts in second language acquisition, mainly focusing on discussing the studies addressing the following two issues: (1) the effects of recasts on the interaction of communication oriented classroom; (2) the role of recasts in promoting interlanguage development.Mixed evidence has been presented by second language (L2) studies regarding the impacts of recasts on second language acquisition.展开更多
Recast is the most frequently used error correction technique adopted by teachers in the communicative oriented classrooms. This article illustrates the reasons for its popularity, also discusses how to use recast eff...Recast is the most frequently used error correction technique adopted by teachers in the communicative oriented classrooms. This article illustrates the reasons for its popularity, also discusses how to use recast effectively in practice.展开更多
Recasts are the most frequently used in class to give corrective feedback.However,there is a hot debate about their effectiveness in facilitating second language acquisition(SLA).The article aims to examine the effect...Recasts are the most frequently used in class to give corrective feedback.However,there is a hot debate about their effectiveness in facilitating second language acquisition(SLA).The article aims to examine the effectiveness and explore ways to optimize the facilitative role of recasts in class.展开更多
Objective: The aim of this study was to compare the effects of different surface treatments on the elemental composition stability of as-received and recast types of NiCr casting alloys. Material and Methods: Six comm...Objective: The aim of this study was to compare the effects of different surface treatments on the elemental composition stability of as-received and recast types of NiCr casting alloys. Material and Methods: Six commercial NiCr dental casting alloys (Kera N, Nodelco, Bellabond, Wiron 99, Metaplus VK, and Tritech D) were used in this study. Seventy-two specimens (12 × 12 × 1.2 mm) were produced using the lost-wax casting process. Three casting protocols were established in relation to the proportion of as-received and recast alloys: Group A (100% as-received metal), Group B (50 wt% new metal, 50 wt% once-recast metal), and Group C (100% once-recast metal). Two specimens in every group received two different surface treatments: sandblasting with 110 μmm Al2O3 or oxidation firing. An elemental analysis was performed with x-ray energy-dispersive spectroscopy. Results were subjected to one-way analysis of variance and Tukey HSD tests. Results: The elemental composition was significantly different in the casting groups and treatment groups (p < 0.05). The lowest mean weight percentage Ni value was recorded for Group C and the highest for Group A. Aluminum-oxide sandblasting of the alloy surface reduced the mean weight percentage for Cr. Conclusion: Recasting metal alloys may adversely affect surface quality.展开更多
Via material erosion in wire electrical discharge machining(WEDM),recast layers form on the surfaces of workpiece.In addition,ultra fine Wire-EDM can be usually cut once.To reduce the thickness of the recast layer as ...Via material erosion in wire electrical discharge machining(WEDM),recast layers form on the surfaces of workpiece.In addition,ultra fine Wire-EDM can be usually cut once.To reduce the thickness of the recast layer as much as possible,the wire electrical discharge-electrochemical machining(WEDCM)method was proposed,which is based on the micro conductivity of the dielectric and microelectrolytic characteristics by adjusting the no-load rate of the pulse in the machining process.Furthermore,a state discrimination and servo control system based on discharge current was designed.The experiment results of different no-load rates show that the electrolytic effects increase as the no-load rate increases,and the main machining process is spark discharge erosion with a no-load rate in the range of 10%to 80%.At 90%no-load rate,the amount of recast layer formation in the forward direction of the wire electrode is almost the same as that of electrolytic dissolution,and it can be practically processed without a recast layer.Compared with10%no-load rate,the kerf width only increases by 7.5%.展开更多
文摘The roles of recasts have been intensively studied in the first language (L1) research. This essay explores the role of recasts in second language acquisition, mainly focusing on discussing the studies addressing the following two issues: (1) the effects of recasts on the interaction of communication oriented classroom; (2) the role of recasts in promoting interlanguage development.Mixed evidence has been presented by second language (L2) studies regarding the impacts of recasts on second language acquisition.
文摘Recast is the most frequently used error correction technique adopted by teachers in the communicative oriented classrooms. This article illustrates the reasons for its popularity, also discusses how to use recast effectively in practice.
文摘Recasts are the most frequently used in class to give corrective feedback.However,there is a hot debate about their effectiveness in facilitating second language acquisition(SLA).The article aims to examine the effectiveness and explore ways to optimize the facilitative role of recasts in class.
文摘Objective: The aim of this study was to compare the effects of different surface treatments on the elemental composition stability of as-received and recast types of NiCr casting alloys. Material and Methods: Six commercial NiCr dental casting alloys (Kera N, Nodelco, Bellabond, Wiron 99, Metaplus VK, and Tritech D) were used in this study. Seventy-two specimens (12 × 12 × 1.2 mm) were produced using the lost-wax casting process. Three casting protocols were established in relation to the proportion of as-received and recast alloys: Group A (100% as-received metal), Group B (50 wt% new metal, 50 wt% once-recast metal), and Group C (100% once-recast metal). Two specimens in every group received two different surface treatments: sandblasting with 110 μmm Al2O3 or oxidation firing. An elemental analysis was performed with x-ray energy-dispersive spectroscopy. Results were subjected to one-way analysis of variance and Tukey HSD tests. Results: The elemental composition was significantly different in the casting groups and treatment groups (p < 0.05). The lowest mean weight percentage Ni value was recorded for Group C and the highest for Group A. Aluminum-oxide sandblasting of the alloy surface reduced the mean weight percentage for Cr. Conclusion: Recasting metal alloys may adversely affect surface quality.
基金the National Natural Science Foundation of China(Nos.51575271 and 51975290)。
文摘Via material erosion in wire electrical discharge machining(WEDM),recast layers form on the surfaces of workpiece.In addition,ultra fine Wire-EDM can be usually cut once.To reduce the thickness of the recast layer as much as possible,the wire electrical discharge-electrochemical machining(WEDCM)method was proposed,which is based on the micro conductivity of the dielectric and microelectrolytic characteristics by adjusting the no-load rate of the pulse in the machining process.Furthermore,a state discrimination and servo control system based on discharge current was designed.The experiment results of different no-load rates show that the electrolytic effects increase as the no-load rate increases,and the main machining process is spark discharge erosion with a no-load rate in the range of 10%to 80%.At 90%no-load rate,the amount of recast layer formation in the forward direction of the wire electrode is almost the same as that of electrolytic dissolution,and it can be practically processed without a recast layer.Compared with10%no-load rate,the kerf width only increases by 7.5%.
