The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective...The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.展开更多
Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-po...Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)展开更多
A reduced model is proposed and analyzed for the simulation of vortexinduced vibrations （VIVs） for turbine blades. A rotating blade is modelled as a uniform cantilever beam, while a van der Pol oscillator is used to...A reduced model is proposed and analyzed for the simulation of vortexinduced vibrations （VIVs） for turbine blades. A rotating blade is modelled as a uniform cantilever beam, while a van der Pol oscillator is used to represent the time-varying characteristics of the vortex shedding, which interacts with the equations of motion for the blade to simulate the fluid-structure interaction. The action for the structural motion on the fluid is considered as a linear inertia coupling. The nonlinear characteristics for the dynamic responses are investigated with the multiple scale method, and the modulation equations are derived. The transition set consisting of the bifurcation set and the hystere- sis set is constructed by the singularity theory and the effects of the system parameters, such as the van der Pol damping. The coupling parameter on the equilibrium solutions is analyzed. The frequency-response curves are obtained, and the stabilities are determined by the Routh-Hurwitz criterion. The phenomena including the saddle-node and Hopf bifurcations are found to occur under certain parameter values. A direct numerical method is used to analyze the dynamic characteristics for the original system and verify the va- lidity of the multiple scale method. The results indicate that the new coupled model is useful in explaining the rich dynamic response characteristics such as possible bifurcation phenomena in the VIVs.展开更多
文摘The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.
文摘Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)
基金Project supported by the National Basic Research Program of China(973 Program)(No.2015CB057405)the National Natural Science Foundation of China(No.11372082)the State Scholarship Fund of China Scholarship Council(CSC)(2014)
文摘A reduced model is proposed and analyzed for the simulation of vortexinduced vibrations （VIVs） for turbine blades. A rotating blade is modelled as a uniform cantilever beam, while a van der Pol oscillator is used to represent the time-varying characteristics of the vortex shedding, which interacts with the equations of motion for the blade to simulate the fluid-structure interaction. The action for the structural motion on the fluid is considered as a linear inertia coupling. The nonlinear characteristics for the dynamic responses are investigated with the multiple scale method, and the modulation equations are derived. The transition set consisting of the bifurcation set and the hystere- sis set is constructed by the singularity theory and the effects of the system parameters, such as the van der Pol damping. The coupling parameter on the equilibrium solutions is analyzed. The frequency-response curves are obtained, and the stabilities are determined by the Routh-Hurwitz criterion. The phenomena including the saddle-node and Hopf bifurcations are found to occur under certain parameter values. A direct numerical method is used to analyze the dynamic characteristics for the original system and verify the va- lidity of the multiple scale method. The results indicate that the new coupled model is useful in explaining the rich dynamic response characteristics such as possible bifurcation phenomena in the VIVs.
