草原综合植被覆盖度(comprehensive vegetation coverage of grassland,CVCG)是反映草原生态状况的一个重要生态指标,是我国生态文明建设的一项重要考核指标。为了能够更好地将草原综合植被覆盖度应用于我国生态文明建设的实践,本文阐...草原综合植被覆盖度(comprehensive vegetation coverage of grassland,CVCG)是反映草原生态状况的一个重要生态指标,是我国生态文明建设的一项重要考核指标。为了能够更好地将草原综合植被覆盖度应用于我国生态文明建设的实践,本文阐述了草原综合植被覆盖度的概念和内涵,详细介绍了草原综合植被覆盖度的计算方法,提出了提高计算精度的注意事项和建议。展开更多
To cope with the demand and supply of electrical load of an interconnected power system of a country, we need to forecast its demand in advance. In this paper, we use a fuzzy system to forecast electrical load on shor...To cope with the demand and supply of electrical load of an interconnected power system of a country, we need to forecast its demand in advance. In this paper, we use a fuzzy system to forecast electrical load on short-term basis. Here, we consider temperature, humidity, seasons of a year and time segments of a day as the parameters, which govern the demand of electrical load. For each of the parameter, we use several membership functions (MFs) and then apply the Mamdani rule on MFs and the output is determined by using the centroid method. Finally, the surface plot reveals the real scenario of the load demand. The difference between actual load and the output of the fuzzy system is found as +1.65% to -13.76%. The concept of the paper can be applied in interconnected power system of Bangladesh to reduce power loss, especially when generation is higher than the demand.展开更多
Intrinsic viscosities for a given polyelectrolyte in salt free and low-salt solvents reported in literatures are normally not comparable, because of inadequate valuation procedures. This article describes a theoretica...Intrinsic viscosities for a given polyelectrolyte in salt free and low-salt solvents reported in literatures are normally not comparable, because of inadequate valuation procedures. This article describes a theoretically justified reliable method, which is free of any model assumptions： The so called Wolf plot （logarithm of the relative viscosity as a function of polymer concentration） enables the unequivocal determination of intrinsic viscosities for all kinds of macromolecules, irrespective of whether they are chain molecules of different architecture or globular polymers, whether they are charged or uncharged. The validation of the method was examined by evaluation of the viscosities of a polyelectrolyte, some uncharged polymers of different architectures, uncharged polymer blends, and some literature data.展开更多
The resonant flow of an incompressible, inviscid fluid with surface tension on varying bottoms was researched. The effects of different bottoms on the nonlinear surface waves were analyzed. The waterfall plots of the ...The resonant flow of an incompressible, inviscid fluid with surface tension on varying bottoms was researched. The effects of different bottoms on the nonlinear surface waves were analyzed. The waterfall plots of the wave were drawn with Matlab according to the numerical simulation of the fKdV equation with the pseudo-spectral method. From the waterfall plots, the results are obtained as follows： for the convex bottom, the waves system can be viewed as a combination of the effects of forward-step forcing and backwardstep forcing, and these two wave systems respectively radiate upstream and downstream without mutual interaction. Nevertheless, the result for the concave bottom is contrary to the convex one. For some combined bottoms, the wave systems can be considered as the combination of positive forcing and negative forcing.展开更多
The non-isothermal kinetics of mechanochemical reduction of Ag2O with graphite was studied by DSC and TGA with a model of fitting Malek approach and a model-free advanced isoconversional method of Vyazovkin. To evalua...The non-isothermal kinetics of mechanochemical reduction of Ag2O with graphite was studied by DSC and TGA with a model of fitting Malek approach and a model-free advanced isoconversional method of Vyazovkin. To evaluate the kinetics parameters, Ag2O–graphite mixture of as-received and milled for 2 and 4 h samples were selected. Based on the results obtained by Vyazovkin method calculation, however, the difference between the maximum and minimum values of activation energy is less than 20%-30%of the average activation energy （（99.38±2.36） kJ/mol） and thermal decomposition of mechanically activated Ag2O for 2 h is a multi-step process. Moreover, the thermal decomposition of mechanically activated Ag2O–graphite powder activated for 4 h is a single-step process （the average activation energy=（93.68±2.26） kJ/mol）. The kinetics modeling shows that the complexity of thermal decomposition of as-received Ag2O–graphite mixture is higher than that of the others. While, the autocatalytic tendency of as-received Ag2O–graphite mixture is lower than that of the others.展开更多
文摘草原综合植被覆盖度(comprehensive vegetation coverage of grassland,CVCG)是反映草原生态状况的一个重要生态指标,是我国生态文明建设的一项重要考核指标。为了能够更好地将草原综合植被覆盖度应用于我国生态文明建设的实践,本文阐述了草原综合植被覆盖度的概念和内涵,详细介绍了草原综合植被覆盖度的计算方法,提出了提高计算精度的注意事项和建议。
文摘To cope with the demand and supply of electrical load of an interconnected power system of a country, we need to forecast its demand in advance. In this paper, we use a fuzzy system to forecast electrical load on short-term basis. Here, we consider temperature, humidity, seasons of a year and time segments of a day as the parameters, which govern the demand of electrical load. For each of the parameter, we use several membership functions (MFs) and then apply the Mamdani rule on MFs and the output is determined by using the centroid method. Finally, the surface plot reveals the real scenario of the load demand. The difference between actual load and the output of the fuzzy system is found as +1.65% to -13.76%. The concept of the paper can be applied in interconnected power system of Bangladesh to reduce power loss, especially when generation is higher than the demand.
基金financially supported by the National Natural Science Foundation of China(No.51273166)the National Basic Research Program of China(No.2010CB732203)the Scientific and Technological Innovation Platform of Fujian Province of China(No.2009J1009)
文摘Intrinsic viscosities for a given polyelectrolyte in salt free and low-salt solvents reported in literatures are normally not comparable, because of inadequate valuation procedures. This article describes a theoretically justified reliable method, which is free of any model assumptions： The so called Wolf plot （logarithm of the relative viscosity as a function of polymer concentration） enables the unequivocal determination of intrinsic viscosities for all kinds of macromolecules, irrespective of whether they are chain molecules of different architecture or globular polymers, whether they are charged or uncharged. The validation of the method was examined by evaluation of the viscosities of a polyelectrolyte, some uncharged polymers of different architectures, uncharged polymer blends, and some literature data.
基金Project supported by the National Natural Science Foundation of China(No.10272044)the Ph. D. Programs Foundation of Ministry of Education of China(No.20040079004)
文摘The resonant flow of an incompressible, inviscid fluid with surface tension on varying bottoms was researched. The effects of different bottoms on the nonlinear surface waves were analyzed. The waterfall plots of the wave were drawn with Matlab according to the numerical simulation of the fKdV equation with the pseudo-spectral method. From the waterfall plots, the results are obtained as follows： for the convex bottom, the waves system can be viewed as a combination of the effects of forward-step forcing and backwardstep forcing, and these two wave systems respectively radiate upstream and downstream without mutual interaction. Nevertheless, the result for the concave bottom is contrary to the convex one. For some combined bottoms, the wave systems can be considered as the combination of positive forcing and negative forcing.
文摘The non-isothermal kinetics of mechanochemical reduction of Ag2O with graphite was studied by DSC and TGA with a model of fitting Malek approach and a model-free advanced isoconversional method of Vyazovkin. To evaluate the kinetics parameters, Ag2O–graphite mixture of as-received and milled for 2 and 4 h samples were selected. Based on the results obtained by Vyazovkin method calculation, however, the difference between the maximum and minimum values of activation energy is less than 20%-30%of the average activation energy （（99.38±2.36） kJ/mol） and thermal decomposition of mechanically activated Ag2O for 2 h is a multi-step process. Moreover, the thermal decomposition of mechanically activated Ag2O–graphite powder activated for 4 h is a single-step process （the average activation energy=（93.68±2.26） kJ/mol）. The kinetics modeling shows that the complexity of thermal decomposition of as-received Ag2O–graphite mixture is higher than that of the others. While, the autocatalytic tendency of as-received Ag2O–graphite mixture is lower than that of the others.
