arXiv subjects

Wei-Rong Zhong

Publications and source records attributed to Wei-Rong Zhong.

15 recordsLinked to original sources

arXiv2011

Chirality- and thickness-dependent thermal conductivity of few-layer graphene: a molecular dynamics study

The thermal conductivity of graphene nanoribbons (layer from 1 to 8 atomic planes) is investigated by using the nonequilibrium molecular dynamics method. We present that the room-temperature thermal conductivity decays monotonically with the number of the layers in few-layer graphene. The superiority of zigzag graphene in thermal conductivity is only available in high temperature region and disappears in multi-layer case. It is explained that the phonon spectral shrink in high frequency induces the change of thermal conductivity. It is also reported that single-layer graphene has better ballistic transport property than the multi-layer graphene.

cond-mat.mes-hall↗

arXiv2011

T-Shape Molecular Heat Pump

We report on the first molecular device of heat pump modeled by a T-shape Frenkel-Kontorova lattice. The system is a three-terminal device with the important feature that the heat can be pumped from the low-temperature region to the high-temperature region through the third terminal. The pumping action is achieved by applying a stochastic external force that periodically modulates the atomic temperature. The temperature, the frequency and the system size dependence of heat pump are briefly discussed.

cond-mat.stat-mech↗

arXiv2011

Different thermal conductance of the inter- and intra-chain interactions in a double-stranded molecular structure

A double-stranded system, modeled by a Frenkel-Kontorova lattice, is studied through nonequilibrium molecular dynamics simulations. We have investigated the thermal conductance influenced by the intra-chain interaction as well as by the inter-chain interaction. It is found that the intra-chain interaction always enhance the thermal conductance. The inter-chain interaction, however, has a positive effect on the thermal conductance in the case of strong nonlinear potential, and has a negative effect on the thermal conductance in the case of weak nonlinear potential. This phenomenon can be explained by the transition of thermal transport mode and the phonon band shift of the particles. It is suggested that the inter-and intra-chain interactions present different thermal properties in double-stranded lattices.

cond-mat.mtrl-sci↗

arXiv2011

Thermal conductivity of deformed carbon nanotubes

We investigate the thermal conductivity of four types of deformed carbon nanotubes by using the nonequilibrium molecular dynamics method. It is reported that various deformations have different influence on the thermal properties of carbon nanotubes. For the bending carbon nanotubes, the thermal conductivity is independent on the bending angle. However, the thermal conductivity increases lightly with XY-distortion and decreases rapidly with Z-distortion. The thermal conductivity does not change with the screw ratio before the breaking of carbon nanotubes but decreases sharply after the critical screw ratio.

cond-mat.mes-hall↗

arXiv2011

Thermal rectification in thickness-asymmetric graphene nanoribbons

Thermal rectification in thickness asymmetric graphene nanoribbons connecting single-layer with multi-layer graphene is investigated by using classical nonequilibrium molecular dynamics. It is reported that the graphene nanoribbons with thickness-asymmetry have a good thermal rectification. The thermal rectification factor depends on temperature as well as the thickness-ratio of the two-segment. Our results provide a direct evidence that the thermal rectifier can be achieved in a nanostructure crossing two- and three-dimension.

cond-mat.mes-hall↗

arXiv2011

Anomalous negative differential thermal resistance in a momentum-conserving lattice

A two-segment Fermi-Pasta-Ulam lattices has been investigated by using nonequilibrium molecular dynamics. Here we present an anomalous negative differential thermal resistance (NDTR) that have not been reported in Frenkel-Kontorova and ϕ_4 lattices up to the present. The NDTR disappears at low temperature region. The region of NDTR shifts from the large to the small temperature difference region as the system size increases. Anomalous dependence of NDTR on the temperature can be explained as the negative effect induced by the nonlinear coupling. The explanation can also cover the phenomenon of NDTR in momentum-nonconserved lattices.

cond-mat.mtrl-sci↗

arXiv2009

Negative differential thermal resistance induced by ballistic transport

Using nonequilibrium molecular-dynamics simulations, we study the temperature dependence of the negative differential thermal resistance that appears in two-segment Frenkel-Kontorova lattices. We apply the theoretical method based on Landauer equation to obtain the relationship between the heat current and the temperature, which states a fundamental interpretation about the underlying physical mechanism of the negative differential thermal resistance. The temperature profiles and transport coefficients are demonstrated to explain the crossover from diffusive to ballistic transport. The finite-size effect is also discussed.

physics.bio-ph↗

arXiv2008

Spatiotemporal Noise Triggering Infiltrative Tumor Growth under Immune Surveillance

A spatiotemporal noise is assumed to reflect the environmental fluctuation in a spatially extended tumor system. We introduce firstly the structure factor to reveal the invasive tumor growth quantitatively. The homogenous environment can lead to an expansive growth of the tumor cells, while the inhomogenous environment underlies an infiltrative growth. The different responses of above two cases are separated by a characteristic critical intensity of the spatiotemporal noise. Theoretical and numerical results present a close annotation to the clinical images.

q-bio.OT↗

arXiv2007

Noise Correlation Induced Synchronization in a Mutualism Ecosystem

Understanding the cause of the synchronization of population evolution is an important issue for ecological improvement. Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show, via theoretical analysis and direct simulation, that noise correlation can induce a synchronization of the mutualists. The time series of mutual species exhibit a chaotic-like fluctuation, which is independent to the noise correlation, however, the chaotic fluctuation of mutual species ratio decreases with the noise correlation. A quantitative parameter defined for characterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.

q-bio.OT↗

arXiv2006

Spatiotemporal Fluctuation Induced Transition in a Tumor Model with Immune Surveillance

We report on a simple model of spatial extend anti-tumor system with a fluctuation in growth rate, which can undergo a nonequilibrium phase transition. Three states as excited, sub-excited and non-excited states of a tumor are defined to describe its growth. The multiplicative noise is found to be double-face: The positive effect on a non-excited tumor and the negative effect on an excited tumor.

physics.bio-ph↗

arXiv2006

Pure multiplicative stochastic resonance of anti-tumor model with seasonal modulability

The effects of pure multiplicative noise on stochastic resonance in an anti-tumor system modulated by a seasonal external field are investigated by using theoretical analyses of the generalized potential and numerical simulations. For optimally selected values of the multiplicative noise intensity quasi-symmetry of two potential minima and stochastic resonance are observed. Theoretical results and numerical simulations are in good quantitative agreement.

q-bio.OT↗

arXiv2005

Sensitive predators and endurant preys in an ecosystem driven by correlated noises

We investigate the Volterra ecosystem driven by correlated noises. The competition of the predators induces an increasing in population density of the predators. The competition of the preys, however, leads the predators to decay. The predators may have better stability under strong correlated noises. The predators undergo a sensitivity to a random environment, whereas the preys exhibit a surprising endurance to this stochasticity.

q-bio.PE↗

arXiv2005

Noise-induced first-order transition in anti-tumor immunotherapy

We studied the single-variable dynamics model of the tumor growth. A first-order phase transition induced by an additive noise is shown to reproduce the main features of tumor growth under immune surveillance. The critical average cells population has a power-law function relationship with the immune coefficient.

physics.med-ph↗

arXiv2005

Stochastic resonance in the growth of a tumor induced by correlated noises

Multiplicative noise is found to divide the growth law of tumors into two parts in a logistic model, which is driven by additive and multiplicative noises simultaneously. The Fokker-Planck equation was also derived to explain the fact that the influence of the intensity of multiplicative noise on the growth of tumor cells has a stochastic resonance-like characteristic. An appropriate intensity of multiplicative noise is benefit to the growth of the tumor cells. The correlation between two sorts of noises weakens the stochastic resonance-like characteristic. Homologous noises promote the growth of the tumor cells.

physics.bio-ph↗

arXiv2005

Influence of Correlated Noises on Growth of a Tumor

We studied the effect of additive and multiplicative noises on the growth of a tumor based on a logistic growth model. The steady-state probability distribution and the average population of the tumor cells were given to explain the important roles of correlated noises in the tumor growth. We found that multiplicative noise induces a phase transition of the tumor growth from an uni-stable state to a bi-stable state; the relationship between the intensity of multiplicative noise and the population of the tumor cells showed a stochastic resonance-like characteristic. It was also confirmed that additive noise weakened rather than extinguish the tumor growth. Homologous noises, however, promote the growth of a tumor. We also discussed about the relationship between the tumor treatment and the model.

physics.bio-ph↗