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
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
Currently, there are a variety of researches on corrective feedback, especially on recasts. Most of researches are experiment-based and depend on the certain context. This paper addresses the question of ＂Is recast t...Currently, there are a variety of researches on corrective feedback, especially on recasts. Most of researches are experiment-based and depend on the certain context. This paper addresses the question of ＂Is recast the most effective form of corrective feedback？＂ by two of Second Language Acquisition （SLA） approaches： cognitive approach and sociolinguistic approach. Empirical research will be used as complement. Theoretically speaking, SLA hypotheses in cognitive approach exist disagreements. Interaction hypothesis favors recast while both input hypothesis and output hypothesis doubt the effectiveness of it. Sociolinguistic approach underscores the significance of appropriate and timely corrective feedback and does not give more credit to certain strategy. Both approaches provide the pedagogical implications and elements to take into account for adopting recasts.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
This paper reviews important second language research on recasts in response to a recent debate between Goo and Mackey （2013） and Lyster and Ranta （2013） in the journal Studies in Second Language Acquisition. It b...This paper reviews important second language research on recasts in response to a recent debate between Goo and Mackey （2013） and Lyster and Ranta （2013） in the journal Studies in Second Language Acquisition. It begins by clarifying the definition of recasts and then examines several controversial issues featuring prominently in the debate, including the theoretical underpinnings of existing research on recasts, mixed findings about their effectiveness in language acquisition, and methodological concerns in effectiveness research. The primary aim of this paper is to demarcate common ground and disagreement that are emerging in this debate and, based on a synthesis and critique of previous empirical studies, to identify directions for future research. It also explores pedagogical implications of recasts research for English-as-a-foreign-language contexts.展开更多
This paper aims to investigate the effects of recasts and working memory on the acquisition of Korean morphological causatives by advanced Chinese learners of Korean. Participants were randomly assigned to two groups...This paper aims to investigate the effects of recasts and working memory on the acquisition of Korean morphological causatives by advanced Chinese learners of Korean. Participants were randomly assigned to two groups： A experimental group and a control group. The experimental group received intensive recasts during task-based interaction, whereas the control group did not. The effects of recasts were measured by two types of tests： An elicited imitation test, as a measure of implicit knowledge, and an untimed grammaticality judgment test, as a measure of explicit knowledge. The findings are as follows. First, from the pretest to the delayed posttest, recasts facilitated the learners＇ acquisition of causative construction by developing both their implicit and explicit knowledge. Second, the results of delayed posttests showed that recasts were more effective in aiding the development of implicit knowledge than explicit knowledge. Third, working memory was found to be a significant covariate in the facilitative effects of recasts on explicit knowledge; that is, it mediated the development of explicit knowledge via recasts as a significant individual difference factor. The effects of recasts were maintained even when the impact of working memory was controlled. （189 words）展开更多
Commercial bribery makes up a high proportion of all corruption involving public functionaries in China. As such, it must be a present and future focus of the fight against corruption. In order to better achieve the o...Commercial bribery makes up a high proportion of all corruption involving public functionaries in China. As such, it must be a present and future focus of the fight against corruption. In order to better achieve the objective of restraining public power, we should adjust the criteria for what constitutes the crime of corruption and the content of the specific assessment of this crime in Chinese criminal law in the light of the characteristics and new manifestations of commercial bribery, with a view to combating it more effectively.View full textDownload full text展开更多
Short-arc machining is a novel electrical discharge machining method that utilizes high-energy arc discharge as the energy carrier.Due to its low cost and high processing efficiency,it has been widely applied in the e...Short-arc machining is a novel electrical discharge machining method that utilizes high-energy arc discharge as the energy carrier.Due to its low cost and high processing efficiency,it has been widely applied in the efficient processing of superalloys.To address the challenges of efficient and high-precision processing of superalloys,a processing method combining short-arc machining with precision milling is employed.Advanced material characterization techniques such as electron backscatter diffraction(EBSD)are utilized to analyze the physical properties of the recast layer and surface crystal characteristics.High-temperature low-cycle fatigue life tests are conducted to investigate the correlation between fatigue life and typical surface integrity parameters(surface roughness,residual stress),as well as crystallographic parameters(grain size,grain orientation spread,geometrically necessary dislocations).Processing parameter optimization is achieved with fatigue life as the target.The results indicate that at high temperatures during short-arc machining,the surface material underwent recrystallisation to form a recast layer with a grain size reduction of 85.5%and a heat affected layer depth of over 400μm.The trends in fatigue life are consistent with changes in residual stress,grain orientation spread and geometrically necessary dislocations.Selecting a larger axial depth of cut and lower feed per tooth is advantageous for achieving a higher fatigue life.The proposed research provides an instruction for high efficient precision machining of superalloys.展开更多
To address problems in surface integrity and machining allowance distribution during combined electric arc-mechanical milling,this paper takes TC4 as the research object,examines the influence of electric arc milling(...To address problems in surface integrity and machining allowance distribution during combined electric arc-mechanical milling,this paper takes TC4 as the research object,examines the influence of electric arc milling(EAM)depth on recast layer thickness and surface roughness,alongside an analysis of the recast layer’s organization characteristics and sur-face morphology.A comparative evaluation of cutting forces,surface roughness,and surface hardening is conducted between combined milling and conventional mechanical milling.Key findings reveal that electric arc machining produces a recast layer with a hardness of 313.21 HV.As the EAM depth increases,the localized recast layer thickness and peak-to-valley(PV)differ-ences also rise.To ensure effective surface defect removal,the machining allowance for subsequent mechanical milling must exceed the combined thickness of the recast layer and the PV difference.Under identical parameters,combined milling yields higher surface roughness(0.584μm)and greater surface hardening(10.4%)compared to mechanical milling alone,alongside an 18.716 N increase in cutting force.Response surface methodology(RSM)analysis identifies feed per tooth as the most significant factor affecting surface roughness,followed by spindle speed,with milling depth having the least influence.展开更多
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%.
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Currently, there are a variety of researches on corrective feedback, especially on recasts. Most of researches are experiment-based and depend on the certain context. This paper addresses the question of ＂Is recast the most effective form of corrective feedback？＂ by two of Second Language Acquisition （SLA） approaches： cognitive approach and sociolinguistic approach. Empirical research will be used as complement. Theoretically speaking, SLA hypotheses in cognitive approach exist disagreements. Interaction hypothesis favors recast while both input hypothesis and output hypothesis doubt the effectiveness of it. Sociolinguistic approach underscores the significance of appropriate and timely corrective feedback and does not give more credit to certain strategy. Both approaches provide the pedagogical implications and elements to take into account for adopting recasts.
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.
文摘This paper reviews important second language research on recasts in response to a recent debate between Goo and Mackey （2013） and Lyster and Ranta （2013） in the journal Studies in Second Language Acquisition. It begins by clarifying the definition of recasts and then examines several controversial issues featuring prominently in the debate, including the theoretical underpinnings of existing research on recasts, mixed findings about their effectiveness in language acquisition, and methodological concerns in effectiveness research. The primary aim of this paper is to demarcate common ground and disagreement that are emerging in this debate and, based on a synthesis and critique of previous empirical studies, to identify directions for future research. It also explores pedagogical implications of recasts research for English-as-a-foreign-language contexts.
文摘This paper aims to investigate the effects of recasts and working memory on the acquisition of Korean morphological causatives by advanced Chinese learners of Korean. Participants were randomly assigned to two groups： A experimental group and a control group. The experimental group received intensive recasts during task-based interaction, whereas the control group did not. The effects of recasts were measured by two types of tests： An elicited imitation test, as a measure of implicit knowledge, and an untimed grammaticality judgment test, as a measure of explicit knowledge. The findings are as follows. First, from the pretest to the delayed posttest, recasts facilitated the learners＇ acquisition of causative construction by developing both their implicit and explicit knowledge. Second, the results of delayed posttests showed that recasts were more effective in aiding the development of implicit knowledge than explicit knowledge. Third, working memory was found to be a significant covariate in the facilitative effects of recasts on explicit knowledge; that is, it mediated the development of explicit knowledge via recasts as a significant individual difference factor. The effects of recasts were maintained even when the impact of working memory was controlled. （189 words）
文摘Commercial bribery makes up a high proportion of all corruption involving public functionaries in China. As such, it must be a present and future focus of the fight against corruption. In order to better achieve the objective of restraining public power, we should adjust the criteria for what constitutes the crime of corruption and the content of the specific assessment of this crime in Chinese criminal law in the light of the characteristics and new manifestations of commercial bribery, with a view to combating it more effectively.View full textDownload full text
基金Supported by National Natural Science Foundation of China(Grant No.52075042)。
文摘Short-arc machining is a novel electrical discharge machining method that utilizes high-energy arc discharge as the energy carrier.Due to its low cost and high processing efficiency,it has been widely applied in the efficient processing of superalloys.To address the challenges of efficient and high-precision processing of superalloys,a processing method combining short-arc machining with precision milling is employed.Advanced material characterization techniques such as electron backscatter diffraction(EBSD)are utilized to analyze the physical properties of the recast layer and surface crystal characteristics.High-temperature low-cycle fatigue life tests are conducted to investigate the correlation between fatigue life and typical surface integrity parameters(surface roughness,residual stress),as well as crystallographic parameters(grain size,grain orientation spread,geometrically necessary dislocations).Processing parameter optimization is achieved with fatigue life as the target.The results indicate that at high temperatures during short-arc machining,the surface material underwent recrystallisation to form a recast layer with a grain size reduction of 85.5%and a heat affected layer depth of over 400μm.The trends in fatigue life are consistent with changes in residual stress,grain orientation spread and geometrically necessary dislocations.Selecting a larger axial depth of cut and lower feed per tooth is advantageous for achieving a higher fatigue life.The proposed research provides an instruction for high efficient precision machining of superalloys.
基金supported by the National Natural Science Foundation of China“Study on the evolution law of discharge channel and deformation suppression method for low-pressure micro-arc milling machining of aerospace thin-walled parts”(52265061)The Tianshan Innovation Team“Robotics and intelligent equipment technology science and technology innovation team”(2022D14002).
文摘To address problems in surface integrity and machining allowance distribution during combined electric arc-mechanical milling,this paper takes TC4 as the research object,examines the influence of electric arc milling(EAM)depth on recast layer thickness and surface roughness,alongside an analysis of the recast layer’s organization characteristics and sur-face morphology.A comparative evaluation of cutting forces,surface roughness,and surface hardening is conducted between combined milling and conventional mechanical milling.Key findings reveal that electric arc machining produces a recast layer with a hardness of 313.21 HV.As the EAM depth increases,the localized recast layer thickness and peak-to-valley(PV)differ-ences also rise.To ensure effective surface defect removal,the machining allowance for subsequent mechanical milling must exceed the combined thickness of the recast layer and the PV difference.Under identical parameters,combined milling yields higher surface roughness(0.584μm)and greater surface hardening(10.4%)compared to mechanical milling alone,alongside an 18.716 N increase in cutting force.Response surface methodology(RSM)analysis identifies feed per tooth as the most significant factor affecting surface roughness,followed by spindle speed,with milling depth having the least influence.
