A Reliable Low-Latency Multipath Routing Algorithm for Urban Rail Transit Ad Hoc Networks.

With the advancement of urban rail transit towards intelligence, the demand for urban rail transit communication has increased significantly, but the traditional urban rail transit vehicle-ground communication system has been unable to meet the future vehicle-ground communication requirements. To improve the performance of vehicle-ground communication, the paper proposes a reliable low-latency multipath routing (RLLMR) algorithm for urban rail transit ad hoc networks. First, RLLMR combines the characteristics of urban rail transit ad hoc networks and uses node location information to configure a proactive multipath to reduce route discovery delay. Second, the number of transmission paths is adaptively adjusted according to the quality of service (QoS) requirements for vehicle-ground communication, and then the optimal path is selected based on the link cost function to improve transmission quality. Third, in order to enhance the reliability of communication, a routing maintenance scheme has been added, and the static node-based local repair scheme is used in routing maintenance to reduce the maintenance cost and time. The simulation results show that compared with traditional AODV and AOMDV protocols, the proposed RLLMR algorithm has good performance in improving latency and is slightly inferior to the AOMDV protocol in improving reliability. However, overall, the throughput of the RLLMR algorithm is better than that of the AOMDV.

Molecular dynamics simulation of the adsorption properties of graphene oxide/graphene composite for alkali metal ions.

As one of the effective methods to remove heavy metals, graphene (G) composite adsorption technology is irreplaceable in water pollution control and water purification, but its adsorption mechanism is not clear. Materials Studio (MS) software was used to simulate the molecular dynamics of the interaction between graphene oxide/graphene (GO/G) composite and alkali metal ion (M+). Based on the calculation of the interaction energy, diffusion coefficient and radial distribution function (RDF), The adsorption law of GO/G on M+ was investigated and its mechanism was revealed. It provides a theoretical basis for the research and development of the adsorption performance of G composite electrode. The calculated results show that the interaction energy between different M+ and GO/G is negative, indicating that the interaction between them is mutual attraction. The energy of GO/G composites and the total energy of M+-GO/G increase with the increase of M+ radius. The larger the hydrated ion radius of M+ is, the larger the diffusion coefficient is. Cs+ diffusion coefficient is slightly lower than rubidium. According to RDF analysis, M+-GO and M+ - O (GO) both have bonding within 3.5 Å and non-bonding after 3.5 Å, and the non-bonding interaction of M+-GO is greater. However, the bonding interaction between M+-O(GO) is larger than the non-bonding interaction, indicating that there are bonding and non-bonding interactions in the system when GO/G composite adsorb M+. The interaction between M+ and GO surface is mainly provided by non-bonding interaction, while the interaction between M+ and O atoms of GO surface is mainly provided by bonding interaction.

Accurate quantification of high-purity uranium in coatings by small solid angle method.

Aiming at quantifying high-purity uranium (235U/236U/238U) in coatings, a series of experiments were carried out by a dedicated small solid angle device. The physical design of the device and the small solid angle method were here in described, focus in particular on the analysis of detection efficiency, the effect of the isotope impurity in the coatings and the correction for the non-uniform distribution of the uranium samples. The results show that the weight of 235U in the coatings is 5.2-5.6 mg, while 4.7-5.0 mg for 238U and 2.2 mg for 236U in the corresponding coatings, with relative experimental uncertainties of 1.0%--1.2%.