Mao-Bin Hu

Detect overlapping and hierarchical community structure in networks

Clustering and community structure is crucial for many network systems and the related dynamic processes. It has been shown that communities are usually overlapping and hierarchical. However, previous methods investigate these two properties of community structure separately. This paper proposes an algorithm (EAGLE) to detect both the overlapping and hierarchical properties of complex community structure together. This algorithm deals with the set of maximal cliques and adopts an agglomerative framework. The quality function of modularity is extended to evaluate the goodness of a cover. The examples of application to real world networks give excellent results.

Traffic experiment reveals the nature of car-following

As a typical self-driven many-particle system far from equilibrium, traffic flow exhibits diverse fascinating non-equilibrium phenomena, most of which are closely related to traffic flow stability and specifically the growth/dissipation pattern of disturbances. However, the traffic theories have been controversial due to a lack of precise traffic data. We have studied traffic flow from a new perspective by carrying out large-scale car-following experiment on an open road section, which overcomes the intrinsic deficiency of empirical observations. The experiment has shown clearly the nature of car-following, which runs against the traditional traffic flow theory. Simulations show that by removing the fundamental notion in the traditional car-following models and allowing the traffic state to span a two-dimensional region in velocity-spacing plane, the growth pattern of disturbances has changed qualitatively and becomes qualitatively or even quantitatively in consistent with that observed in the experiment.

Urban traffic from the perspective of dual graph

Abstract.Urban traffic is modeled using a dual graph representation of the urban transport network, where roads are mapped to nodes and intersections are mapped to links. The proposed model considers both the navigation of the vehicles in the network and the motion of the vehicles along roads. The vehicle-holding ability of roads and the vehicle-turning ability at intersections are also incorporated. The overall handling ability of the system can be quantified by a phase transition from free flow to congestion. Simulations show that the systems handling ability greatly depends on the topology of the transportation network. In general, a well-planned grid can hold more vehicles, and its overall handling ability is much greater than that of a growing self-organized network.

The effect of bandwidth in scale-free network traffic

This paper models the effects of bandwidth on the traffic capacity of scale-free networks. We investigate the decrease of the system traffic capacity and the variation of the optimal local routing coefficient αc, induced by the restriction of bandwidth. For low bandwidth, the same optimal value of αc emerges for two different cases of node capacity, namely C = constant and Ci = ki, where ki denotes the degree of the i-th node. By investigating the number of packets at each node in the free-flow state, we provide analytical explanations for the optimal value of αc. Average packet travelling time, distribution of packet travelling time, and average visits per node divided by the node connectivity are also studied.

An Efficient DNA‐Fueled Molecular Machine for the Discrimination of Single‐Base Changes

A new strategy for single-base polymorphism (SNP) detection based on the assembly of DNA-AuNPs (gold nanoparticles) driven by a DNA-fueled molecular machine, is established and optimized. It is highly efficient, works at room temperature, and is easy to handle. A single-base change on an oligonucleotide strand is unambiguously discriminated for either SNPs or insertions and deletions (indels). The strategy is demonstrated to detect a mutation in the breast cancer gene BRCA1 in homogeneous solution at room temperature.

A unified framework for the pareto law and Matthew effect using scale-free networks

Abstract.We investigate the accumulated wealth distribution by adopting evolutionary games taking place on scale-free networks. The system self-organizes to a critical Pareto distribution (1897) of wealth P(m)∼m-(v+1) with 1.6 < v <2.0 (which is in agreement with that of U.S. or Japan). Particularly, the agents personal wealth is proportional to its number of contacts (connectivity), and this leads to the phenomenon that the rich gets richer and the poor gets relatively poorer, which is consistent with the Matthew Effect present in society, economy, science and so on. Though our model is simple, it provides a good representation of cooperation and profit accumulation behavior in economy, and it combines the network theory with econophysics.

Triangular clustering in document networks

Document networks have the characteristic that a document node, e.g. a webpage or an article, carries meaningful content. Properties of document networks are not only affected by topological connectivity between nodes, but are also strongly influenced by the semantic relation between the content of the nodes. We observed that document networks have a large number of triangles and a high value clustering coefficient. Also there is a strong correlation between the probability of formation of a triangle and the content similarity among the three nodes involved. We propose the degree-similarity product (DSP) model, which well reproduces these properties. The model achieves this by using a preferential attachment mechanism that favours the linkage between nodes that are both popular and similar. This work is a step forward towards a better understanding of the structure and evolution of document networks.

Bulk induced phase transition in driven diffusive systems

This paper studies a weakly and asymmetrically coupled three-lane driven diffusive system. A non-monotonically changing density profile in the middle lane has been observed. When the extreme value of the density profile reaches ρ = 0.5, a bulk induced phase transition occurs which exhibits a shock and a continuously and smoothly decreasing density profile which crosses ρ = 0.5 upstream or downstream of the shock. The existence of double shocks has also been observed. A mean-field approach has been used to interpret the numerical results obtained by Monte Carlo simulations. The current minimization principle has excluded the occurrence of two or more bulk induced shocks in the general case of nonzero lane changing rates.

Phase transition in a mesoscopic ring with multiple diffusive channels

Abstract This paper studies a periodic one-dimensional exclusion process constituted by multiple diffusive channels and a common driven part. We have performed mean field analysis for the phase diagram, the density profiles, and the currents, which is in good agreement with the Monte Carlo simulations. In particular, in the special case that the diffusive channels are identical, the phase boundaries have been derived explicitly. It is shown that, in the driven part, the low density–high density region and the low density region shrink and will finally vanish with the increase of the number of diffusive channels. On the other hand, the high density region and the low density–high density region vanish if the total number of particles keeps constant. Numerical examples indicate that these features might be extended to a general case in which the diffusive channels are not identical.

Traffic flow in a Manhattan-like urban system

In this paper, a cellular automaton model of vehicular traffic in Manhattan-like urban system is proposed. In this model, the origin-destination trips and traffic lights have been considered. The system exhibits three different states, i.e., moving state, saturation state and global deadlock state. With a grid coarsening method, vehicle distribution in the moving state and the saturation state has been studied. Interesting structures (e.g., windmill-like one, T-shirt-like one, Y-like one) have been revealed. A metastability of the system is observed in the transition from saturation state to global deadlock state. The effect of advanced traveller information system (ATIS), the traffic light period, and the traffic light switch strategy have also been investigated.