Recent astrophysical measurements strongly suggest the existence of a missing energy component dubbed dark energy that is responsible for the current accelerated expansion of the universe.A new class of modified gravi...Recent astrophysical measurements strongly suggest the existence of a missing energy component dubbed dark energy that is responsible for the current accelerated expansion of the universe.A new class of modified gravity theory is introduced which yields a universe accelerating in time and dominated by dark energy.The new modified gravity model constructed here concurrently includes a Gauss-Bonnet invariant term,barotropic fluid with a time-dependent equation of state parameter,a Coleman-Weinberg（CW） potential-like expression V（φ） =ξφm lnφn and a new Einstein-Hilbert term f（R,φ） =E（φ） R which depends on both the scalar curvature and the scalar fieldφthrough a generic logarithmic function E（φ） =lnφ.Here m and n take different values from the standard CW potential andξis a real parameter. It was shown that the presence of these terms provides many useful features which are discussed in some detail.展开更多
We discuss a new class of RSH braneworld cosmology exhibiting accelerated expansion and dominated byquintessence. It is explicitly demonstrated that the universe expansion history (transition from inflation to deceler...We discuss a new class of RSH braneworld cosmology exhibiting accelerated expansion and dominated byquintessence. It is explicitly demonstrated that the universe expansion history (transition from inflation to decelerationepoch to acceleration and effective quintessence era) may naturally occur in such unified theory for some classes of inversescalar potentials. Besides a decaying effective cosmological constant, the model incorporates an increasing black holemass, an increasing Maxwellian electrical charge with cosmic time and a time-dependent brane tension. The cosmologicalmodel exhibits several features of cosmological and astrophysical interest for both the early and late universe consistentwith recent observations, in particular the ones concerned with the gravitational constants, black holes masses andcharges and variation of the gauge coupling parameters with cosmic time. One interesting mark of the constructedmodel concerns the fact that a black hole mass surrounded by quintessence energy may increase with time even if thehorizon disappears.展开更多
CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a th...CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is limited.In this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition environment.The decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium calculations.The chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical analysis.The injection position and angle of the CF4 were controlled in order to enhance the decomposition rate.The vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma flame.In addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped reactor.As a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.展开更多
Thermal flow characteristics and the methane conversion reaction in a low power arc plasma reactor for efficient storage and transport of methane,which is the main component of shale gas,were simulated.The temperature...Thermal flow characteristics and the methane conversion reaction in a low power arc plasma reactor for efficient storage and transport of methane,which is the main component of shale gas,were simulated.The temperature and velocity distributions were calculated according to the type of discharge gases and arc current level by a self-developed magnetohydrodynamics (MHD)code and a commercial ANSYS-FLUENT code;the transport of chemical species was analyzed as including the chemical reactions of methane conversion.The simulated results were verified by the comparison of calculated and measured arc voltages with permissible low error as under 4%.Three C2 hydrocarbon gases with ethane (C2H6),ethylene (C2H4),and acetylene (C2H2)were selected as the converted species of methane from experimental data.The mass fraction of C2 hydrocarbons and hydrogen as the product of the conversion reaction at the reactor was also calculated.Those values show good agreement with the actual experimental results in that the major conversion reaction occurred in C2H2 and hydrogen,and the conversions to C2H6,C2H4,and hydrogen were minor reactions of methane pyrolysis conversion.展开更多
我们在从 M 理论激发的 S-1 上讨论特别 d 维的 Gauss-Bonnet-dilatonic 宇宙 compactified。我们检验许多有趣的后果被表明并且讨论 in some details 的动态方程的时间进化。在合理条件下面，讨论模型能提供机制认识到，在高尺寸(d >...我们在从 M 理论激发的 S-1 上讨论特别 d 维的 Gauss-Bonnet-dilatonic 宇宙 compactified。我们检验许多有趣的后果被表明并且讨论 in some details 的动态方程的时间进化。在合理条件下面，讨论模型能提供机制认识到，在高尺寸(d > 4 ) ，宇宙的加速的扩大面对黑暗精力，没有幽灵精力的存在并且没有某内部尺寸的收缩。展开更多
文摘Recent astrophysical measurements strongly suggest the existence of a missing energy component dubbed dark energy that is responsible for the current accelerated expansion of the universe.A new class of modified gravity theory is introduced which yields a universe accelerating in time and dominated by dark energy.The new modified gravity model constructed here concurrently includes a Gauss-Bonnet invariant term,barotropic fluid with a time-dependent equation of state parameter,a Coleman-Weinberg（CW） potential-like expression V（φ） =ξφm lnφn and a new Einstein-Hilbert term f（R,φ） =E（φ） R which depends on both the scalar curvature and the scalar fieldφthrough a generic logarithmic function E（φ） =lnφ.Here m and n take different values from the standard CW potential andξis a real parameter. It was shown that the presence of these terms provides many useful features which are discussed in some detail.
文摘We discuss a new class of RSH braneworld cosmology exhibiting accelerated expansion and dominated byquintessence. It is explicitly demonstrated that the universe expansion history (transition from inflation to decelerationepoch to acceleration and effective quintessence era) may naturally occur in such unified theory for some classes of inversescalar potentials. Besides a decaying effective cosmological constant, the model incorporates an increasing black holemass, an increasing Maxwellian electrical charge with cosmic time and a time-dependent brane tension. The cosmologicalmodel exhibits several features of cosmological and astrophysical interest for both the early and late universe consistentwith recent observations, in particular the ones concerned with the gravitational constants, black holes masses andcharges and variation of the gauge coupling parameters with cosmic time. One interesting mark of the constructedmodel concerns the fact that a black hole mass surrounded by quintessence energy may increase with time even if thehorizon disappears.
文摘CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is limited.In this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition environment.The decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium calculations.The chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical analysis.The injection position and angle of the CF4 were controlled in order to enhance the decomposition rate.The vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma flame.In addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped reactor.As a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.
文摘Thermal flow characteristics and the methane conversion reaction in a low power arc plasma reactor for efficient storage and transport of methane,which is the main component of shale gas,were simulated.The temperature and velocity distributions were calculated according to the type of discharge gases and arc current level by a self-developed magnetohydrodynamics (MHD)code and a commercial ANSYS-FLUENT code;the transport of chemical species was analyzed as including the chemical reactions of methane conversion.The simulated results were verified by the comparison of calculated and measured arc voltages with permissible low error as under 4%.Three C2 hydrocarbon gases with ethane (C2H6),ethylene (C2H4),and acetylene (C2H2)were selected as the converted species of methane from experimental data.The mass fraction of C2 hydrocarbons and hydrogen as the product of the conversion reaction at the reactor was also calculated.Those values show good agreement with the actual experimental results in that the major conversion reaction occurred in C2H2 and hydrogen,and the conversions to C2H6,C2H4,and hydrogen were minor reactions of methane pyrolysis conversion.
文摘我们在从 M 理论激发的 S-1 上讨论特别 d 维的 Gauss-Bonnet-dilatonic 宇宙 compactified。我们检验许多有趣的后果被表明并且讨论 in some details 的动态方程的时间进化。在合理条件下面，讨论模型能提供机制认识到，在高尺寸(d > 4 ) ，宇宙的加速的扩大面对黑暗精力，没有幽灵精力的存在并且没有某内部尺寸的收缩。
