As China's energy intensity fluctuated in recent years, it is necessary to examine whether this fluctuation happened at a regional level. This paper establishes a decomposition model by using the structural decomp...As China's energy intensity fluctuated in recent years, it is necessary to examine whether this fluctuation happened at a regional level. This paper establishes a decomposition model by using the structural decomposition analysis (SDA) method at a regional level. Then this model is employed to empirically analyze the changes of Beijing's energy intensity. The conclusions are as follows: during 2002-2010, except petroleum, the energy intensity decreased and the changes were mostly attributed to the technology changes, while the final use variation actually increased the energy intensity; comparing different periods of 2002-2010, the decline rates of energy intensity for coal and hydropower were decreasing, resulting from the production technology being more energy-intensive than before; the energy intensity changes of petroleum firstly increased substantially and then decreased moderately.展开更多
This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust,...This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust, torque, and stroke）. In this model, a drilling process is divided into successive cycles. Each cycle includes two motions： feed and cutting. According to this model, drilling torque includes four components generated from cutting, friction, feed, and idle running respectively, the first three items are all proportional to the UCS （uniaxial compressive strength） when the penetration rate is constant. Laboratory tests verified the correctness and effectiveness of the proposed model qualitatively. Especially, the influence of friction on the flank face and the idle running was confirmed. Field experiments were performed. The results showed good correlation between the torque, penetration rate, and UCS. The proposed model and equations engender the possibility of eliminating useless components of cutting forces when investigating the relation between mechanical data and physical properties of rocks.展开更多
This article uses the refined Laspeyres index decomposition method to examine the overall trends and characteristics of carbon emissions in eight Chinese industries for the period 1994-2008. The results show that ever...This article uses the refined Laspeyres index decomposition method to examine the overall trends and characteristics of carbon emissions in eight Chinese industries for the period 1994-2008. The results show that every one percentage point increase in economic scale will result in an average increase of 15 Mt （million tonnes） in carbon emissions. However, different industries vary greatly in terms of marginal carbon emissions caused by economic growth. The economic structure＇s bias toward heavy industry fuels the increase of carbon emissions： every one percentage point rise in the share of manufacturing industry produces an average of 56 Mt carbon emissions. Technological progress helps reduce energy intensity and serves as a core driver in reducing carbon emissions, in that every one percentage point decrease in energy intensity will cause an average reduction of 33 Mt in carbon emissions. Our coal-dominated energy structure has resulted in a persistently high level of carbon emissions, suggesting that the reduction effect brought about by changes in energy structureis not significant. Nevertheless, lowering the density of overall carbon emissions is a positive signal, indicating that China is optimizing its energy structure. Only by promoting industrial restructuring, optimizing energy structure, encouraging energy-saving technologies and technological innovation, and reorienting industry can China achieve low-carbon development and control pollution.展开更多
Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. ...Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. Unified analytical solutions not only involve generally traditional solutions which are based on the Hock-Brown （H-B） failure criterion or the non-linear twin-shear failure criterion, but also involve other new results. The results of the radius of plastic zone, radial displacements and stresses are obviously different using three rock masses when different values of the unified failure criterion parameter or different material behavior models are used. For a given condition, the radius of plastic zone and radial displacements are reduced by increasing the unified failure criterion parameter. The latent potentialities of rock mass result from considering the effect of intermediate principal stress. It is shown that proper choices of the failure criterion and the material behavior model for rock mass are significant in the tunnel design.展开更多
In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-densi...In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-density matrix formalism.Here,we investigate the intersubband optical absorption coefficients and refractive index changes as a function of the triangle side(L) and the incident optical intensity(I).According to the obtained results,it is found that:(i) The total refractive index changes increase and shift towards lower energies when the triangle side increases.(ii) The total absorption coefficient decreases as the triangle side increases.Also,the resonance peak shifts towards lower energies by increasing the triangle side.展开更多
Based on the definition of second order moment and the approximate three-dimensional analytical formula for probe detected laser beam passing through a cat-eye optical lens with center shelter and oblique detector, th...Based on the definition of second order moment and the approximate three-dimensional analytical formula for probe detected laser beam passing through a cat-eye optical lens with center shelter and oblique detector, the analytical expression of the encirclement power ratio of the cat-eye effect reflected light under far-field condition has been deduced. Variable laws of light intensity at the return place and encirclement power ratio are performed by numerical calculation, and are analyzed physically. The results show that the light intensity at the return place decreases monotonically with the increases of the diameter, incidence angle, tilted angle of the detector and the center shelter ratio, but the relationships between these parameters and the encirclement power ratio are all nonmonotonic. The reasonable choice of the focal shift size would result in the largest light intensity at the return place and the largest erirclenent power ratio.展开更多
Analytical solution for spherically symmetric nonstationary oscillations of acoustic and elastic solid sphere is given.Time dependence of potential,kinetic and internal energy of a solid sphere is analyzed.The receive...Analytical solution for spherically symmetric nonstationary oscillations of acoustic and elastic solid sphere is given.Time dependence of potential,kinetic and internal energy of a solid sphere is analyzed.The received results are of practical importance for a wide range of problems connected to testing of material dynamic strength parameters and to the problems of optimizing(minimizing)energy needed for fracture of solids.展开更多
基金Supported by Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA05150600)National Natural Science Foundation of China (No. 71273027 and No. 70903066)Beijing Planning Office of Philosophy and Social Science (No. 11JGC105)
文摘As China's energy intensity fluctuated in recent years, it is necessary to examine whether this fluctuation happened at a regional level. This paper establishes a decomposition model by using the structural decomposition analysis (SDA) method at a regional level. Then this model is employed to empirically analyze the changes of Beijing's energy intensity. The conclusions are as follows: during 2002-2010, except petroleum, the energy intensity decreased and the changes were mostly attributed to the technology changes, while the final use variation actually increased the energy intensity; comparing different periods of 2002-2010, the decline rates of energy intensity for coal and hydropower were decreasing, resulting from the production technology being more energy-intensive than before; the energy intensity changes of petroleum firstly increased substantially and then decreased moderately.
文摘This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust, torque, and stroke）. In this model, a drilling process is divided into successive cycles. Each cycle includes two motions： feed and cutting. According to this model, drilling torque includes four components generated from cutting, friction, feed, and idle running respectively, the first three items are all proportional to the UCS （uniaxial compressive strength） when the penetration rate is constant. Laboratory tests verified the correctness and effectiveness of the proposed model qualitatively. Especially, the influence of friction on the flank face and the idle running was confirmed. Field experiments were performed. The results showed good correlation between the torque, penetration rate, and UCS. The proposed model and equations engender the possibility of eliminating useless components of cutting forces when investigating the relation between mechanical data and physical properties of rocks.
基金a stage result supported by the Major Program of the National Social Science Fund of China(08AJY032,07AJY010)Program for New Century Excellent Talents in University of Ministry of Education(NCET-10-0409)
文摘This article uses the refined Laspeyres index decomposition method to examine the overall trends and characteristics of carbon emissions in eight Chinese industries for the period 1994-2008. The results show that every one percentage point increase in economic scale will result in an average increase of 15 Mt （million tonnes） in carbon emissions. However, different industries vary greatly in terms of marginal carbon emissions caused by economic growth. The economic structure＇s bias toward heavy industry fuels the increase of carbon emissions： every one percentage point rise in the share of manufacturing industry produces an average of 56 Mt carbon emissions. Technological progress helps reduce energy intensity and serves as a core driver in reducing carbon emissions, in that every one percentage point decrease in energy intensity will cause an average reduction of 33 Mt in carbon emissions. Our coal-dominated energy structure has resulted in a persistently high level of carbon emissions, suggesting that the reduction effect brought about by changes in energy structureis not significant. Nevertheless, lowering the density of overall carbon emissions is a positive signal, indicating that China is optimizing its energy structure. Only by promoting industrial restructuring, optimizing energy structure, encouraging energy-saving technologies and technological innovation, and reorienting industry can China achieve low-carbon development and control pollution.
基金Project (No.SJ08E204) supported by the Natural Science Foundation of Shanxi Province,China
文摘Unified analytical solutions are presented for the predictions of the stresses and displacements around a circular opening based on nonqinear unified failure criterion and the elastic-brittle-plastic softening model. Unified analytical solutions not only involve generally traditional solutions which are based on the Hock-Brown （H-B） failure criterion or the non-linear twin-shear failure criterion, but also involve other new results. The results of the radius of plastic zone, radial displacements and stresses are obviously different using three rock masses when different values of the unified failure criterion parameter or different material behavior models are used. For a given condition, the radius of plastic zone and radial displacements are reduced by increasing the unified failure criterion parameter. The latent potentialities of rock mass result from considering the effect of intermediate principal stress. It is shown that proper choices of the failure criterion and the material behavior model for rock mass are significant in the tunnel design.
文摘In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-density matrix formalism.Here,we investigate the intersubband optical absorption coefficients and refractive index changes as a function of the triangle side(L) and the incident optical intensity(I).According to the obtained results,it is found that:(i) The total refractive index changes increase and shift towards lower energies when the triangle side increases.(ii) The total absorption coefficient decreases as the triangle side increases.Also,the resonance peak shifts towards lower energies by increasing the triangle side.
文摘Based on the definition of second order moment and the approximate three-dimensional analytical formula for probe detected laser beam passing through a cat-eye optical lens with center shelter and oblique detector, the analytical expression of the encirclement power ratio of the cat-eye effect reflected light under far-field condition has been deduced. Variable laws of light intensity at the return place and encirclement power ratio are performed by numerical calculation, and are analyzed physically. The results show that the light intensity at the return place decreases monotonically with the increases of the diameter, incidence angle, tilted angle of the detector and the center shelter ratio, but the relationships between these parameters and the encirclement power ratio are all nonmonotonic. The reasonable choice of the focal shift size would result in the largest light intensity at the return place and the largest erirclenent power ratio.
基金supported by Russian Foundation for Basic Research(Grant Nos.FRBR grants 12-01-33049,13-01-00598,12-01-31224,14-01-00814)scientific programs of Russian Academy of Sciences and grants of the president of Russia for young scientist and FP7 EU MARIE CURIE Project TAMER No.610547
文摘Analytical solution for spherically symmetric nonstationary oscillations of acoustic and elastic solid sphere is given.Time dependence of potential,kinetic and internal energy of a solid sphere is analyzed.The received results are of practical importance for a wide range of problems connected to testing of material dynamic strength parameters and to the problems of optimizing(minimizing)energy needed for fracture of solids.
