A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was...A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was used to simulate the heat transfer process which enables to acquire accurate results through highly complicated modeling and intensive computation. An alternative approach to mesh the material into small cells was also presented. The effective medium theory accounts for the effective thermal conductivity of cells while the equivalent unit is subsequently applied in numerical simulation to analyze the effective thermal conductivity of the porous ceramics. A new expression for the effective thermal conductivity, allowing for some structure factors such as volume fraction of pores and thermal conductivity, was put forward, and the results of its application was proved to be close to those of the mathematical simulation.展开更多
This paper proposes a new eddy current method, named equivalent unit method （EUM）, for the thickness measurement of the top copper film ofmultilayer interconnects in the chemical mechanical polishing （CMP） process...This paper proposes a new eddy current method, named equivalent unit method （EUM）, for the thickness measurement of the top copper film ofmultilayer interconnects in the chemical mechanical polishing （CMP） process, which is an important step in the integrated circuit （IC） manufacturing. The influence of the underneath circuit layers on the eddy current is modeled and treated as an equivalent film thickness. By subtracting this equivalent film component, the accuracy of the thickness measure- ment of the top copper layer with an eddy current sensor is improved and the absolute error is 3 nm for sampler measurement.展开更多
Trampling is one of the three impact activities(trampling,defoliation,and excretion) performed by a grazing animal on grassland and also the major reason for range degradation.Little is known about the result of tramp...Trampling is one of the three impact activities(trampling,defoliation,and excretion) performed by a grazing animal on grassland and also the major reason for range degradation.Little is known about the result of trampling-induced feedback among the soil environment,grass,and their interrelationship.In addition, more information is needed about the effects of animal trampling on the managed grazing ecosystems.In typical steppe of loess plateau regions,where the management objective is to maintain the grassland ecosystem structure and function,the impacts of grazing trampling could be a serious problem.The object of the study was to separately evaluate the effect of trampling on the typical steppe in Huanxian County,eastern Gansu Province,China.A series of field experiments were conducted for two years including the tailing-up observation of trampling intensity of Tan-sheep in summer rotational grazing trail,trampling homogeneity trial,two-factor trail of simulated precipitation and experimental trampling.The results are as follows.1.Trampling intensity(TI) was proposed by this paper as the trampling area or trampling pressure created by a single or multiple grazing livestock per hectare during a unit time under free or rotational grazing.It had three expression methods: trampling pressure method,trampling area method,trampling frequency method.The trampling unit and Trampling Equivalent Unit(TEU) were put forward for the first time in order to define the calculation and conversion standard of TI.2.By tailing-up observation of the flocks on typical steppe of Huanxian County in Eastern Gansu Province,China,the regression analysis shows that livestock trampling intensity was increased by the power function of grazing intensity.This fully demonstrated that the trampling effects played a key role in the wholesomeness maintenance of grassland and the adjustment and control of the trampling effects of grazing livestock should be an important aspect of grazing management.3.Trampler was manufactured to imitate the mechanic展开更多
文摘A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was used to simulate the heat transfer process which enables to acquire accurate results through highly complicated modeling and intensive computation. An alternative approach to mesh the material into small cells was also presented. The effective medium theory accounts for the effective thermal conductivity of cells while the equivalent unit is subsequently applied in numerical simulation to analyze the effective thermal conductivity of the porous ceramics. A new expression for the effective thermal conductivity, allowing for some structure factors such as volume fraction of pores and thermal conductivity, was put forward, and the results of its application was proved to be close to those of the mathematical simulation.
文摘This paper proposes a new eddy current method, named equivalent unit method （EUM）, for the thickness measurement of the top copper film ofmultilayer interconnects in the chemical mechanical polishing （CMP） process, which is an important step in the integrated circuit （IC） manufacturing. The influence of the underneath circuit layers on the eddy current is modeled and treated as an equivalent film thickness. By subtracting this equivalent film component, the accuracy of the thickness measure- ment of the top copper layer with an eddy current sensor is improved and the absolute error is 3 nm for sampler measurement.
文摘Trampling is one of the three impact activities(trampling,defoliation,and excretion) performed by a grazing animal on grassland and also the major reason for range degradation.Little is known about the result of trampling-induced feedback among the soil environment,grass,and their interrelationship.In addition, more information is needed about the effects of animal trampling on the managed grazing ecosystems.In typical steppe of loess plateau regions,where the management objective is to maintain the grassland ecosystem structure and function,the impacts of grazing trampling could be a serious problem.The object of the study was to separately evaluate the effect of trampling on the typical steppe in Huanxian County,eastern Gansu Province,China.A series of field experiments were conducted for two years including the tailing-up observation of trampling intensity of Tan-sheep in summer rotational grazing trail,trampling homogeneity trial,two-factor trail of simulated precipitation and experimental trampling.The results are as follows.1.Trampling intensity(TI) was proposed by this paper as the trampling area or trampling pressure created by a single or multiple grazing livestock per hectare during a unit time under free or rotational grazing.It had three expression methods: trampling pressure method,trampling area method,trampling frequency method.The trampling unit and Trampling Equivalent Unit(TEU) were put forward for the first time in order to define the calculation and conversion standard of TI.2.By tailing-up observation of the flocks on typical steppe of Huanxian County in Eastern Gansu Province,China,the regression analysis shows that livestock trampling intensity was increased by the power function of grazing intensity.This fully demonstrated that the trampling effects played a key role in the wholesomeness maintenance of grassland and the adjustment and control of the trampling effects of grazing livestock should be an important aspect of grazing management.3.Trampler was manufactured to imitate the mechanic
