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Multi-robot path planning is a hot problem in the field of robotics. Compared with single-robot path planning, complex problems such as obstacle avoidance and mutual collaboration need to be considered. This paper proposes an efficient leader follower-ant colony optimization (LF-ACO) to solve the collaborative path planning problem. Firstly, a new Multi-factor heuristic functor is proposed, the distance factor heuristic function and the smoothing factor heuristic function. This improves the convergence speed of the algorithm and enhances the smoothness of the initial path. The leader-follower structure is reconstructed for the position constraint problem of multi-robots in a grid environment. Then, the pheromone of the leader ant and the follower ants are used in the pheromone update rule of the ACO to improve the search quality of the formation path. To improve the global search capability, a max-min ant strategy is used. Finally, the path is optimized by the turning point optimization algorithm and dynamic cut-point method to improve path quality further. The simulation and experimental results based on MATLAB and ROS show that the proposed method can successfully solve the path planning and formation problem.

Thymosin β4 (Tβ4) is involved in cytokine secretion, nerve development, stimulation of wound healing, cancer progression, growth rate and immune response. The functions of Tβ4 in vertebrate have been widely studied, but the activities of each THY domain in invertebrate multirepeat β-thymosins remain unclear. In the present study, a new four THY domains Tβ4 gene was identified and characterized. The four THY domains have certain similarities in amino acid sequence, but MrThy4-D1 and MrThy4-D4 are predicted with α-helical structure, while MrThy4-D2 and MrThy4-D3 are random coils. The CD spectra results have confirmed the α-helical structure of synthetic MrThy4-D1 and MrThy4-D4 peptides. MrTβ4 was mostly expressed in hemocyte and hepatopancreas. The expression of MrTβ4 could be significantly up-regulated after Aeromonas hydrophila infections. The recombinant MrTβ4 protein was successfully produced and purified as the inclusion body. After refolding, both the recombinant MrTβ4 protein and the synthetic D1, D4 peptides exhibit certain antimicrobial activities to the selected Gram-negative and Gram-positive bacteria. The rMrTβ4 protein, synthetic MrThy4-D1 and MrThy4-D4 peptides all could increase the survival rate of M. rosenbergii against A. hydrophila infections, by improving the circulating hemocytes count, enhancing the antioxidant enzyme activities in hemolymph, or directly inhibition effect on bacteria. The present study not only enrich the understanding of the immune system of shrimp, but also lay an important foundation for the further development of MrTβ4 and antimicrobial peptide drugs.

It has been reported that community structure of crustacean zooplankton is related to environment factors and abundance of predacious fishes. Most studies, however were based on observation on independent water bodies, which may complicate the results with uninterested factors. A large river-connected lake has partitioned regions with the characteristics of either a river or a lake albeit allowing exchanging of zooplankton of different regions. Thus, a river-connected lake is an ideal system for studying distribution of crustacean zooplankton and investigating its affecting factors. In this study, 11 stations of a large river-connected lake, Lake Gaoyou, were sampled in all four seasons. Taxonomic diversity and species abundance were recorded and their correlation with environmental factors was investigated. A total of 26 and 22 species of crustacean zooplankton were recorded in the river and lake region, respectively. The abundance of crustacean in the river region was significantly higher than that in the lake region. The relative abundance of calanoids and Bosmina fatalis in the river region was lower than that in the lake region, whereas the abundance of cyclopoids and other cladocera species was lower in the lake region than in the river region. Cluster analysis showed that crustacean assemblages could be divided into two, one cluster grouping all sites from the river region, and the other cluster included all sites in the lake region. According to Pearson correlation and canonical correspondence analysis, the distribution of crustacean was positively correlated with water temperature and chlorophyll a gradient. Chlorophyll a and fish abundance are excellent predictors on spatial distribution of crustacean zooplankton in Lake Gaoyou. Our findings may also help in planning of bighead carp stocking in Lake Gaoyou.

For the network instability problem caused by trust decisions among wireless senor networks nodes (WSNs), this paper introduces an imbalance reward and punishment mechanism. The unreliable factors exist in the real networks, so this paper introduced the package loss rate to build a trust evolution model for wireless senor networks nodes based on imbalance reward and punishment mechanism. By the trust evolution model, the state of interaction of nodes is deduced. At last, through the experiment, various changes of nodes selecting strategy and the effect of the imbalance reward and punishment mechanism on the evolution of the convergence time are analyzed, and the effect of the imbalance rewards and penalties mechanism is verified by the results of the WSNs, which is a kind of node’s initial trust strategy. The imbalance rewards and penalties mechanism for the evolution of the slow convergence in the model mechanism, and can reduce the initial nodes selection strategy trust ratio, which provides the theory basis for the design WSNs trust mechanism.

The distribution of nodes is an important aspect of energy consumption research in wireless sensor network. It affects the energy consumption mainly in the coverage and density of the nodes in wireless sensor networks. In this paper, starting from random distribution of the sensor nodes, considering the communication probability between nodes, research energy consumption of random distribution of nodes within a single regular hexagon and between two adjacent regular hexagons. This paper proposed a concept of probability cumulative distribution function of simulating energy consumption, and derived probability cumulative distribution model of simulating energy consumption. Then simulate this concept and analyze the simulation results to obtain theoretically optimal communication range. The simulation results show, this model can be derived from probability of energy consumption within a specific communication range and get the best communication range. Nodes communication can minimize energy consumption in the obtained optimum communication range. The method provides a theoretical and practical basis for estimating large-scale energy consumption.