It seems to be a common misconception that children's first language acquisition (Ll) and adults' second language acquisition (L2) are far from each other. Some studies on immigrants show that children of immi...It seems to be a common misconception that children's first language acquisition (Ll) and adults' second language acquisition (L2) are far from each other. Some studies on immigrants show that children of immigrant families who master new languages are more like locals than their parents. Of course, many adults can master a high level of second language. However, compared with the mother tongue (95%), the success rate of second language acquisition is only 5%, considering the children with language disorders. This phenomenon raises the question of the possibility and effectiveness of second language acquisition, especially for adults whose brains have been shaped by first language.展开更多
Taking CPU time cost and analysis accuracy into account, dynamic explicit finite ele- ment method is adopted to optimize the forming process of autobody panels that often have large sizes and complex geometry. In this...Taking CPU time cost and analysis accuracy into account, dynamic explicit finite ele- ment method is adopted to optimize the forming process of autobody panels that often have large sizes and complex geometry. In this paper, for the sake of illustrating in detail how dynamic explicit finite element method is applied to the numerical simulation of the autobody panel forming process,an example of optimization of stamping process pain meters of an inner door panel is presented. Using dynamic explicit finite element code Ls-DYNA3D, the inner door panel has been optimized by adapting pa- rameters such as the initial blank geometry and position, blank-holder forces and the location of drawbeads, and satisfied results are obtained.展开更多
This research develops a knowledge model for Software Process Improvement (SPI) project based on knowledge creation theory and its twenty-four measurement items, and proposes two hypothesizes about the interaction of ...This research develops a knowledge model for Software Process Improvement (SPI) project based on knowledge creation theory and its twenty-four measurement items, and proposes two hypothesizes about the interaction of explicit knowledge and tacit knowledge in SPI. Eleven factors are extracted through statistical analysis. Three knowledge-creation practices for capturing tacit knowledge contribute greatly to SPI, which are communication among members, crossover collaboration in practical work and pair programming. Two knowledge-creation practices for capturing explicit knowledge have significant positive impact on SPI, which are integrating project document and on-the-job training. Ultimately, suggestions for improvement are put forward, that is, encouraging communication among staff and integrating documents in real time, and future research is also illustrated.展开更多
The Explicit Upstream FEM (EU-FEM) proposed in this paper not only possesses the advantages of saving memory and CPU time for FDM, but also fits boundary easily, arranges nodal points flexibly and makes local grids fi...The Explicit Upstream FEM (EU-FEM) proposed in this paper not only possesses the advantages of saving memory and CPU time for FDM, but also fits boundary easily, arranges nodal points flexibly and makes local grids fine down conveniently. The software package, which consists of EU-FEM models and pre/post-processing skills, has been widely used to estuary, near-shore, bay, lake and complex waters with many islands and channels. In addition to flow field, this model can be used to calculate the distribution fields of pollutants, temperature, salinity, sediment, and oil spill, and can be used to case study of estuary regulation projects. Some practical applications are presented and some problems discussed.展开更多
The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and...The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and dynamic process. Planar strain clutch models including roller, inner-ring and outer-ring were built, and transient wedging process was analyzed with an explicit dynamics meth- od. The modeling of stress and strain distribution and variation of two kinds of contact surfaces show that there are three stages named slipping, wedging and binding respectively during whole wed- ging process. Meanwhile the geometric structures of contact surfaces greatly influence the peak stress and strain distribution of the wedging process of the roller and inner-ring. The load bearing performance of contact surfaces with logarithmic spiral curve is better than that with straight line. Our study provides theoretical foundation for design and further optimization of wedging contact surface of an overrunning clutch in a dual-turbine hydrodynamic torque converter.展开更多
In Hilbert spaces , through improving some corresponding conditions in some literature and extending some recent relevent results, a strong convergence theorem of some implicit iteration process for pesudocon-traction...In Hilbert spaces , through improving some corresponding conditions in some literature and extending some recent relevent results, a strong convergence theorem of some implicit iteration process for pesudocon-traction mappings and explicit iteration process for nonexpansive mappings were established. And by using the result, some iterative solution for some equation of response diffusion were obtained.展开更多
The space-time fractional advection dispersion equations are linear partial pseudo-differential equations with spatial fractional derivatives in time and in space and are used to model transport at the earth surface. ...The space-time fractional advection dispersion equations are linear partial pseudo-differential equations with spatial fractional derivatives in time and in space and are used to model transport at the earth surface. The time fractional order is denoted by β∈ and ?is devoted to the space fractional order. The time fractional advection dispersion equations describe particle motion with memory in time. Space-fractional advection dispersion equations arise when velocity variations are heavy-tailed and describe particle motion that accounts for variation in the flow field over entire system. In this paper, I focus on finding the precise explicit discrete approximate solutions to these models for some values of ?with ?, ?while the Cauchy case as ?and the classical case as ?with ?are studied separately. I compare the numerical results of these models for different values of ?and ?and for some other related changes. The approximate solutions of these models are also discussed as a random walk with or without a memory depending on the value of . Then I prove that the discrete solution in the Fourierlaplace space of theses models converges in distribution to the Fourier-Laplace transform of the corresponding fractional differential equations for all the fractional values of ?and .展开更多
文摘It seems to be a common misconception that children's first language acquisition (Ll) and adults' second language acquisition (L2) are far from each other. Some studies on immigrants show that children of immigrant families who master new languages are more like locals than their parents. Of course, many adults can master a high level of second language. However, compared with the mother tongue (95%), the success rate of second language acquisition is only 5%, considering the children with language disorders. This phenomenon raises the question of the possibility and effectiveness of second language acquisition, especially for adults whose brains have been shaped by first language.
文摘Taking CPU time cost and analysis accuracy into account, dynamic explicit finite ele- ment method is adopted to optimize the forming process of autobody panels that often have large sizes and complex geometry. In this paper, for the sake of illustrating in detail how dynamic explicit finite element method is applied to the numerical simulation of the autobody panel forming process,an example of optimization of stamping process pain meters of an inner door panel is presented. Using dynamic explicit finite element code Ls-DYNA3D, the inner door panel has been optimized by adapting pa- rameters such as the initial blank geometry and position, blank-holder forces and the location of drawbeads, and satisfied results are obtained.
文摘This research develops a knowledge model for Software Process Improvement (SPI) project based on knowledge creation theory and its twenty-four measurement items, and proposes two hypothesizes about the interaction of explicit knowledge and tacit knowledge in SPI. Eleven factors are extracted through statistical analysis. Three knowledge-creation practices for capturing tacit knowledge contribute greatly to SPI, which are communication among members, crossover collaboration in practical work and pair programming. Two knowledge-creation practices for capturing explicit knowledge have significant positive impact on SPI, which are integrating project document and on-the-job training. Ultimately, suggestions for improvement are put forward, that is, encouraging communication among staff and integrating documents in real time, and future research is also illustrated.
文摘The Explicit Upstream FEM (EU-FEM) proposed in this paper not only possesses the advantages of saving memory and CPU time for FDM, but also fits boundary easily, arranges nodal points flexibly and makes local grids fine down conveniently. The software package, which consists of EU-FEM models and pre/post-processing skills, has been widely used to estuary, near-shore, bay, lake and complex waters with many islands and channels. In addition to flow field, this model can be used to calculate the distribution fields of pollutants, temperature, salinity, sediment, and oil spill, and can be used to case study of estuary regulation projects. Some practical applications are presented and some problems discussed.
基金Supported by the National Natural Science Foundation of China(51475041)the Ministerial Level Advanced Research Foundation(40402060103)the Ministerial Basic Products Innovation Program(VTDP2104)
文摘The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and dynamic process. Planar strain clutch models including roller, inner-ring and outer-ring were built, and transient wedging process was analyzed with an explicit dynamics meth- od. The modeling of stress and strain distribution and variation of two kinds of contact surfaces show that there are three stages named slipping, wedging and binding respectively during whole wed- ging process. Meanwhile the geometric structures of contact surfaces greatly influence the peak stress and strain distribution of the wedging process of the roller and inner-ring. The load bearing performance of contact surfaces with logarithmic spiral curve is better than that with straight line. Our study provides theoretical foundation for design and further optimization of wedging contact surface of an overrunning clutch in a dual-turbine hydrodynamic torque converter.
文摘In Hilbert spaces , through improving some corresponding conditions in some literature and extending some recent relevent results, a strong convergence theorem of some implicit iteration process for pesudocon-traction mappings and explicit iteration process for nonexpansive mappings were established. And by using the result, some iterative solution for some equation of response diffusion were obtained.
文摘The space-time fractional advection dispersion equations are linear partial pseudo-differential equations with spatial fractional derivatives in time and in space and are used to model transport at the earth surface. The time fractional order is denoted by β∈ and ?is devoted to the space fractional order. The time fractional advection dispersion equations describe particle motion with memory in time. Space-fractional advection dispersion equations arise when velocity variations are heavy-tailed and describe particle motion that accounts for variation in the flow field over entire system. In this paper, I focus on finding the precise explicit discrete approximate solutions to these models for some values of ?with ?, ?while the Cauchy case as ?and the classical case as ?with ?are studied separately. I compare the numerical results of these models for different values of ?and ?and for some other related changes. The approximate solutions of these models are also discussed as a random walk with or without a memory depending on the value of . Then I prove that the discrete solution in the Fourierlaplace space of theses models converges in distribution to the Fourier-Laplace transform of the corresponding fractional differential equations for all the fractional values of ?and .
