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Routing optimization in wireless sensor networks facilitates to reduce the overhead of the maintaining of wireless sensor networks and extend the lifetime of wireless sensor networks. Collection tree-based routing protocol, which does not require route discovery, has been widely used for low overheads of calculation and storage. However, with collection tree-based routing protocol, some nodes easily become the bottleneck points and quickly run out of the energy. To deal with this drawback, this article proposes a collection tree-oriented mesh routing strategy with cooperatively consuming the residual energy among the neighboring sensor nodes. The collection tree-oriented mesh routing is formulated into a linear programming problem with the purpose to maximize the network lifetime. By solving the optimization problem, the optimal mesh routing and data forwarding scheme is derived. Experimental simulations show that the proposed collection tree-oriented mesh routing optimization strategy can extend the network lifetime by more than 20%.

In order to ensure the normal operation of the power system, it is an essential concern for optimizing inspection path based on limited human and material resources. Despite a wide body of literatures for path planning, however, a framework to optimize grouping and inspection path with minimum number of inspection teams is still lacking. Given the target transmission lines and constrained work hours for each inspector, we study the theoretical solution of the minimum number of inspection teams for task assignment. Furthermore, we develop an improved k-means algorithm, and combine with heuristic intelligent algorithms, such as ant colony algorithm and simulated annealing algorithm, we put forward a universal framework for optimizing grouping and inspection path with minimum number of inspection teams. By applying our framework to both synthetic transmission line and the real transmission lines in Jinhua city, the results verify the theoretical solution of the minimum number of inspection teams. In addition, experimental results demonstrate that our framework can provide quasi-optimal inspection paths and balance work hours for each team. By comparison of the results with different algorithms, we find that the simulated annealing algorithm works the best. Our work paves a new way to solve the vehicle routing problem, travelling salesman problem and some other related problems.

DMF-stabilized Au nanoparticles (NPs) with three different particle sizes were prepared by controlling the reaction temperatures and times. In the absence of any additional ligands, these Au NPs showed high catalytic activity in the Ullmann homocoupling of aryl iodides in DMF. The effects of Au particle size on the coupling reaction were investigated by the use of three Au catalysts with mean particle sizes of ca. 1.0 nm, 2.5 nm, and 5.5 nm, respectively. The catalytic activity of the Au NPs was found to be in the order of Au (2.5 nm) > Au (<1.0 nm) > Au (5.5 nm), indicating that surface Au atoms do not have the same catalytic activity toward such a homocoupling reaction. [ABSTRACT FROM AUTHOR]

Purpose. This study was conducted to introduce a novel modified surgical technique for laparoscopic splenectomy and esophagogastric devascularization (LSED) and its safety and efficiency. Methods. From June 2016 to November 2017, 86 patients were diagnosed with portal hypertension and serious gastroesophageal varices in our center. Of them, 32 patients underwent LSED and 54 received the modified LSED. Results and outcomes were compared retrospectively. Results. There were no significant differences in preoperative patient characteristics of the two groups. No intraoperative deaths took place in both groups. The intraoperative blood loss was apparently less in the M-LSED group (P0.05). Conclusions. Our study showed that the modified LSED was a safe and effective approach with low conversion rate, less intraoperative bleeding, less blood transfusion, and shorter operation time and postoperative hospital stay compared with classical LSED. Moreover, this technique is relatively easy and technically feasible.

IEEE 802.15.5 standard introduces the mesh routing which improves reliability and robustness of routing in wireless sensor network since there are multiple routes from source node to destination node. To achieve energy efficiency for a long network lifetime, the asynchronous energy saving is proposed in IEEE 802.15.5, which includes the receiver-initiated unicast mechanism and the sender-initiated broadcast mechanism. In this article, an improved asynchronous energy saving named semi-synchronous energy saving is proposed to deal with the energy inefficiency from idle listening existing in asynchronous energy saving. In semi-synchronous energy saving, every node maintains the wake/sleep schedule information of nodes in its two-hop neighborhood and uses this information to calculate the wake-up time of an interested neighbor that the data will be sent to, which reduces idle listening time in both unicast and broadcast mechanisms. A low delay routing mechanism is also proposed based on the wake/sleep schedule information of neighbors. Furthermore, the optimal guard time to guarantee receiving the wake-up notification from neighbor in the presence of clock drift is investigated for saving energy. The performance analysis and simulation evaluation show that semi-synchronous energy saving saves more than 80% of energy with less than 30% memory cost compared to asynchronous energy saving, and it also improves the time of completing broadcast and the end-to-end delay.