arXiv subjects

Hongru Ma

Publications and source records attributed to Hongru Ma.

25 records · Page 2Linked to original sources

arXiv2008

Revisit of interfacial free energy of the hard sphere system near hard wall

We propose a simple Monte Carlo method to calculate the interfacial free energy between the substrate and the material. Using this method we investigate the interfacial free energys of the hard sphere fluid and solid phases near a smooth hard wall. According to the obtained interfacial free energys of the coexisting fluid and solid phases and the Young equation we are able to determine the contact angle with high accuracy, cos$θ$ = 1:010(31), which indicates that a smooth hard wall can be wetted completely by the hard sphere crystal at the interface between the wall and the hard sphere fluid.

cond-mat.soft↗

arXiv2008

Elasticity of a polydisperse hard-sphere crystal

A general Monte Carlo simulation method of calculating the elastic constants of polydisperse hard-sphere colloidal crystal was developed. The elastic constants of a size polydisperse hard sphere fcc crystal is calculated. The pressure and three elastic constants(C11, C12 and C44) increase significantly with the polydispersity. It was also found from extrapolation that there is a mechanical terminal polydispersity above which a fcc crystal will be mechanically unstable.

cond-mat.soft↗

arXiv2008

Transformation media that turn a narrow slit into a large window

Based on the transformation media theory, the authors propose a way to replace a wide window with a narrow slit filled with designed metamaterial to achieve the same transmittance as the one of the window. Numerical simulations for a two dimensional case are given to illustrate the ideas and the performance of the design.

physics.optics↗

arXiv2007

Scattering of elastic waves by elastic spheres in a NaCl-type phononic crystal

Based on the formalism developed by Psarobas et al [Phys. Rev. B 62, 278(2000)], which using the multiple scattering theory to calculate properties of simple phononic crystals, we propose a very simple method to study the NaCl-type phononic crystal. The NaCl-type phononic crystal consists of two kinds of non-overlapping elastic spheres with different mass densities, $L\acute{a}me$ coefficients and radius following the same periodicity of the ions in the real NaCl crystal. We focus on the (001) surface, and view the crystal as a sequence of planes of spheres, each plane of spheres has identical 2D periodicity. We obtained the complex band structure of the infinite crystal associated with this plane, and also calculated the transmission, reflection and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness.

cond-mat.mtrl-sci↗

arXiv2006

Effective delivering capacity in traffic dynamics based on scale-free network

We investigate the percentage of delivering capacities that are actually consumed in a typical traffic dynamics where the capacities are uniformly assigned over a scale-free network. Theoretical analysis, as well as simulations, reveal that there are a large number of idle nodes under both free and weak congested state of the network. It is worth noting that there is a critical value of effective betweenness to classify nodes in the congested state, below which the node has a constant queue size but above which the queue size increases with time. We also show that the consumption ratio of delivering capacities can be boosted to nearly 100% by adopting a proper distribution of the capacities, which at the same time enhances the network efficiency to the maximum for the current routing strategy.

cond-mat.stat-mech↗

arXiv2004

Network of tRNA Gene Sequences

We showed in this paper that similarity network can be used as an powerful tools to study the relationship of tRNA genes. We constructed a network of 3719 tRNA gene sequences using simplest alignment and studied its topology, degree distribution and clustering coefficient. It is found that the behavior of the network shift from fluctuated distribution to scale-free distribution when the similarity degree of the tRNA gene sequences increase. tRNA gene sequences with the same anticodon identity are more self-organized than the tRNA gene sequences with different anticodon identities and form local clusters in the network. An interesting finding in our studied is some vertices of the local cluster have a high connection with other local clusters, the probable reason is given. Moreover, a network constructed by the same number of random tRNA sequences is used to make comparisons. The relationships between properties of the tRNA similarity network and the characters of tRNA evolutionary history are discussed.

q-bio.MN↗

arXiv2004

Epidemic Spreading in Dynamic Small World Networks

In this paper, we use a series of small world networks to simulate the epidemic spreading in the real world. To make our model more similar to the real world, we employ a parameter $p_{move}$ to denote its moving probability, which corresponds with the general mobility of individuals in realistic social network. The networks keep the same small world properties when they are varying. And the SIRS model is used to simulate the disease propagation. From these simulations we see the moving probability of a small world network has a profound effect on the velocity for the spread of an infection. The quantitative results show that the characteristic time $τ$ of infection at initial stage decreases exponentially with $p_{move}$.

nlin.AO↗