In the evaluation of some simulation systems, only small samples data are gotten due to the limited conditions. In allusion to the evaluation problem of small sample data, an interval estimation approach with the impr...In the evaluation of some simulation systems, only small samples data are gotten due to the limited conditions. In allusion to the evaluation problem of small sample data, an interval estimation approach with the improved grey confidence degree is proposed.On the basis of the definition of grey distance, three kinds of definition of the grey weight for every sample element in grey estimated value are put forward, and then the improved grey confidence degree is designed. In accordance with the new concept, the grey interval estimation for small sample data is deduced. Furthermore,the bootstrap method is applied for more accurate grey confidence interval. Through resampling of the bootstrap, numerous small samples with the corresponding confidence intervals can be obtained. Then the final confidence interval is calculated from the union of these grey confidence intervals. In the end, the simulation system evaluation using the proposed method is conducted. The simulation results show that the reasonable confidence interval is acquired, which demonstrates the feasibility and effectiveness of the proposed method.展开更多
Over the past three decades,a growing number of different theories in second language acquisition field have come out in an effort to provide explanations as to how language learning takes place,to figure out what var...Over the past three decades,a growing number of different theories in second language acquisition field have come out in an effort to provide explanations as to how language learning takes place,to figure out what variables are effective for second language acquisition as well as to offer guidance to mass second language learners and language teachers.Because behind every teaching approach exists certain kind of theory of language acquisition and good theory in turn can help students master language skills in an effective and efficient way.Each theory is considered to have contributed to the field by highlighting a specific aspect of the language acquisition process.Second language acquisition theories are intrinsically related with various disciplines such as applied linguistics,psychology,education,sociolinguistics,neurology,etc.Considering the impossibility to elaborate all second language theories,I will focus on sociocultural theory and bottleneck hypothesis in second language acquisition.There is an overview which follows the introduction to the Sociocultural Theory and Bottleneck Hypothesis and its contribution to second language acquisition respectively,and then I will evaluate them to see their contributions to the SLA disciplinary development.展开更多
consists of forecasting for the total reserves of regional mineral resources and evaluation,compreIn general,based on evaluated objects and factors involved,evaluation of mineral resources hensive evaluation of region...consists of forecasting for the total reserves of regional mineral resources and evaluation,compreIn general,based on evaluated objects and factors involved,evaluation of mineral resources hensive evaluation of regional mineral resources, and economic and technical evaluation of deposits. Here a region can be a country, a province, or a mining area, while a deposit is mainly related to a single type of mineral, although it can contain more than one types of minerals. In the past, to assess mineral resources was primarily to evaluate and forecast the total reserves of regional mineral resources. With the advancement of science, technology, and economy, the evaluation of mineral resources has developed from forecasting the reserves of them to comprehensively evaluating them on the basis of numerous factors.展开更多
Thermal-mechanical coupling effect causes a large stress within porous ceramics at high temperatures,resulting in strength attenuation and product reliability decline.Thermal shock resistance is one of the key factors...Thermal-mechanical coupling effect causes a large stress within porous ceramics at high temperatures,resulting in strength attenuation and product reliability decline.Thermal shock resistance is one of the key factors to characterize the reliability of ceramic materials under thermal-mechanical coupling effect.It is important to study the thermal shock resistance of the porous ceramics to evaluate their service performance and improve their service life.To better evaluate the effect of the thermal shock resistance on properties of the porous ceramics,the evaluation theories,experimental characterization methods and influencing factors about the thermal shock performance of the porous ceramics were reviewed in this paper,and some future research directions were prospected.展开更多
文摘In the evaluation of some simulation systems, only small samples data are gotten due to the limited conditions. In allusion to the evaluation problem of small sample data, an interval estimation approach with the improved grey confidence degree is proposed.On the basis of the definition of grey distance, three kinds of definition of the grey weight for every sample element in grey estimated value are put forward, and then the improved grey confidence degree is designed. In accordance with the new concept, the grey interval estimation for small sample data is deduced. Furthermore,the bootstrap method is applied for more accurate grey confidence interval. Through resampling of the bootstrap, numerous small samples with the corresponding confidence intervals can be obtained. Then the final confidence interval is calculated from the union of these grey confidence intervals. In the end, the simulation system evaluation using the proposed method is conducted. The simulation results show that the reasonable confidence interval is acquired, which demonstrates the feasibility and effectiveness of the proposed method.
文摘Over the past three decades,a growing number of different theories in second language acquisition field have come out in an effort to provide explanations as to how language learning takes place,to figure out what variables are effective for second language acquisition as well as to offer guidance to mass second language learners and language teachers.Because behind every teaching approach exists certain kind of theory of language acquisition and good theory in turn can help students master language skills in an effective and efficient way.Each theory is considered to have contributed to the field by highlighting a specific aspect of the language acquisition process.Second language acquisition theories are intrinsically related with various disciplines such as applied linguistics,psychology,education,sociolinguistics,neurology,etc.Considering the impossibility to elaborate all second language theories,I will focus on sociocultural theory and bottleneck hypothesis in second language acquisition.There is an overview which follows the introduction to the Sociocultural Theory and Bottleneck Hypothesis and its contribution to second language acquisition respectively,and then I will evaluate them to see their contributions to the SLA disciplinary development.
文摘consists of forecasting for the total reserves of regional mineral resources and evaluation,compreIn general,based on evaluated objects and factors involved,evaluation of mineral resources hensive evaluation of regional mineral resources, and economic and technical evaluation of deposits. Here a region can be a country, a province, or a mining area, while a deposit is mainly related to a single type of mineral, although it can contain more than one types of minerals. In the past, to assess mineral resources was primarily to evaluate and forecast the total reserves of regional mineral resources. With the advancement of science, technology, and economy, the evaluation of mineral resources has developed from forecasting the reserves of them to comprehensively evaluating them on the basis of numerous factors.
文摘Thermal-mechanical coupling effect causes a large stress within porous ceramics at high temperatures,resulting in strength attenuation and product reliability decline.Thermal shock resistance is one of the key factors to characterize the reliability of ceramic materials under thermal-mechanical coupling effect.It is important to study the thermal shock resistance of the porous ceramics to evaluate their service performance and improve their service life.To better evaluate the effect of the thermal shock resistance on properties of the porous ceramics,the evaluation theories,experimental characterization methods and influencing factors about the thermal shock performance of the porous ceramics were reviewed in this paper,and some future research directions were prospected.
