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351.
以滴汞电极体系为模型,对非恒稳恒电势动态不可逆电极过程中的耗散-涨落效应进行了系统的研究.基于滴汞电极体系的电化学特征,提出了一个简化的含时随机热力学模型,从而可能对这类重要的含时物理化学过程进行涨落和耗散的定量分析.借助该简化的模型,成功地建立了恒电势滴汞电极过程的基本随机热力学公式,由此推出耗散-涨落效应的理论极谱曲线.在滴汞电极生长缓慢及扩散步骤严重滞后情况下,含时的滴汞电极过程将趋于在有效扩散层厚度演化的慢流型上的准定态过程.在这种准定态近似下,具体分析了涨落对极谱曲线的影响.结果表明,在涨落影响可以忽略的近平衡区,从耗散-涨落导出的极谱方程与从平衡态Nernst公式导出的极谱方程完全吻合.还计算了一个涨落诱导的极谱曲线偏离的典型范例. 相似文献
352.
The effects of orientation and silicon chain length on the electronic transport properties for linear silicon chains sandwiched between two graphene electrodes are investigated by using non-equilibrium Green’s functions combined with density functional theory. Our results demonstrate that the conductance of single silicon chains can hardly be affected by its orientation, as there is negligible difference between the conductance of tilted and un-tilted chains, and the conductance is impacted greatly by the length of chains, i.e. the transmission coefficient is doubled for double chains. The equilibrium conductance of single silicon chains shows even-odd oscillating behavior, and its tendency decreases with the increase of the chain length. The non-equilibrium electronic transport properties for all types of chains are also calculated, and all current–voltage curves of silicon chains show a linear character. The frontier molecular orbitals, the total and projected density of states are used to analyse the electronic transport properties for all types of chains. 相似文献
353.
Thermoelectricity is a thermorelated property that is of great importance in single-molecule junctions. The electrical conductance (σ), electron-derived thermal conductance (κel) and Seebeck coefficient (S) of B80-based single-molecule junctions are investigated by using density functional theory in combination with non-equilibrium Green’s function. When the distance between the left/right electrodes is 11.4 Å, the relationship between σ and κel obeys the Wiedemann–Franz law very well because of the strong hybridization between B80 molecular orbitals and the surface states of Au electrodes. Furthermore, the calculated Lorenz number is close to the famous value in metal or degenerate semiconductors. In addition, S is only –19.09 μV/K at 300 K, thus leading to the smaller electron’s thermoelectric figure of merit (ZelT = S2σT/κel). Interestingly, the strain and chemical potential can modulate B80-based single-molecule junctions from n-type to p-type when the compressive strain reaches –0.6 Å or the chemical potential shifts to –0.16 eV. This might be attributed that S reflects the asymmetry in the electrical conductance with respect to the chemical potential and is proportional to the slopes of the transmission spectrum. 相似文献
354.
针对非平衡态外推边界处理方法在某些条件下发生质量泄漏的问题,结合质量守恒定律对其进行修正,建立一种新的质量守恒型的边界处理格式.其基本思想是在边界处定义一个虚拟密度来修正平衡态分布函数,使得系统质量守恒.以重力作用下的密度场及磁流体模拟问题为例,利用该格式进行分析,讨论质量泄露问题的本质及各种因素的影响.通过对三种典型的流动:二维Poiseuille流、Couette流、Womersley流的模拟,验证该边界格式的计算精度和稳定性. 相似文献
355.
Since Gibbs synthesized a general equilibrium statistical ensemble theory, many theorists have attempted to generalized the Gibbsian theory to
non-equilibrium phenomena domain, however the status of the theory of non-equilibrium phenomena can not be said as firm as well established as the
Gibbsian ensemble theory. In this work, we present a framework for the non-equilibrium statistical ensemble formalism based on a subdynamic kinetic
equation (SKE) rooted from the Brussels-Austin school and followed by some up-to-date works. The constructed key is to use a similarity transformation between Gibbsian ensembles formalism based on Liouville equation and the subdynamic ensemble formalism based on the SKE. Using this formalism, we study the spin-Boson system, as cases of weak coupling or strongly coupling, and obtain the reduced density operators for the Canonical ensembles easily. 相似文献
356.
A linear stability analysis is carried out to study viscoelastic fluid convection in a horizontal porous layer heated from below and cooled from above when the solid and fluid phases are not in a local thermal equilibrium. The modified Darcy–Brinkman–Maxwell model is used for the momentum equation and two-field model is used for the energy equation each representing the solid and fluid phases separately. The conditions for the onset of stationary and oscillatory convection are obtained analytically. Linear stability analysis suggests that, there is a competition between the processes of viscoelasticity and thermal diffusion that causes the first convective instability to be oscillatory rather than stationary. Elasticity is found to destabilize the system. Besides, the effects of Darcy number, thermal non-equilibrium and the Darcy–Prandtl number on the stability of the system are analyzed in detail. 相似文献
357.
This paper investigates theoretically the influence of magnetization
on fatigue life by using non-equilibrium statistical theory of
fatigue fracture for metals. The fatigue microcrack growth rate is
obtained from the dynamic equation of microcrack growth, where the
influence of magnetization is described by an additional term in the
potential energy of microcrack. The statistical value of fatigue
life of metal under magnetic field is derived, which is expressed in
terms of magnetic field and macrophysical as well as microphysical
quantities. The fatigue life of AISI 4140 steel in static magnetic
field from this theory is basically consistent with the experimental
data. 相似文献
358.
In this paper, we study spatially periodic system with infinite
globally coupled oscillators driven by temporal-spatial noise and
subject to a constant force. The results show that the system
exhibits the phenomena of the non-equilibrium phase transition,
transport of particles, and the anomalous hysteresis cycle
for the mean field and the probability current. 相似文献
359.
360.
Sourendu Gupta D Indumathi S Banerjee R Basu M Dittmar RV Gavai F Gelis D Ghosh Sourendu Gupta D Indumathi Asmita Mukherjee 《Pramana》2000,55(1-2):327-333
This is the report of the QCD working group at WHEPP-6. Discussions and work on heavy ion collisions, polarized scattering,
and collider phenomenology are reported. 相似文献