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Cooperative localization is an attractive method to improve both the coverage and accuracy of the positioning systems in GNSS-challenged environments. However, as the number of agents increases, the computational complexity and communication overhead increase dramatically, which are two main bottlenecks of its application in a practical system. In this paper, we focus on reducing the system overhead of the message passing-based cooperative localization algorithm in dense wireless networks. Weighted samples are used to represent the salient characteristics of the local message, and a Gaussian parametric message passing rule is designed to reduce the burden of the network traffic. A relative spatial relationship between the target and its neighbor anchor nodes is proposed to concentrate the samples where the messages have significant mass. Based on the equivalent Fisher information matrix, a node selection scheme is put forward to refine the most contributing link combination for the position. Then, an efficient message calculation method which exploits the Taylor expansion to reduce the system overhead is deduced. The convergence property of the proposed algorithm is further analyzed. Simulation results show that the proposed algorithm leads to excellent performance at the communication overhead and computational complexity, with small losses in localization accuracy.

Multivariate organic acids can modify the structure and morphology of materials to some extent. In this work, the addition of oxalic acid can make the morphology of ZnIn2S4 become uniform, the crystal structure of ZnIn2S4 can change from cubic to hexagonal, and the photocatalytic activity was improved. The dual Z-scheme ZnIn2S4/BiOCl heterojunction was successfully fabricated by a two-step hydrothermal-hydrolytic method. The concept of green chemistry was used to make full use of thiourea, and the rapid decomposition of Rh B and TC was realized by ZIS/BOC-8 under visible light in a shorter period time than other photocatalysts in this system. In order to investigate the relationship between the structure and properties of the catalyst, XRD, FT-IR, SEM, HRTEM, UV–vis DRS, XPS and other characterization technologies were used to analyze the structure, morphology, optical properties of the samples, showing that ZnIn2S4/BiOCl have been successfully synthesized indicates the existence of Z-scheme heterojunction structure. PL, TRPL and EIS analysis showed that the Z-scheme heterostructures could rapidly promote the separation of holes and photo-induced electron carriers, enhancing the photocatalytic performance and stability. The photocatalytic degradation results showed that the degradation rate of Rh B and TC by ZIS/BOC-8 were more than 92% within 30 min, comparing with other catalyst, ZIS/BOC-8 showed preferable visible light catalytic degradation activity, and the order of catalytic activity was as follows: ZIS/BOC-8 > BiOCl-S > BiOCl, ZnIn2S4. Moreover, the degradation pathway of Rh B was discussed by 3D-EEM and LC-MS, and the photocatalytic mechanism of the system was proposed, especially the mechanism of photocatalytic degradation of Rh B by ZIS/BOC under visible light.

Interconnected three-dimension (3D) networks of novel helical carbon nanotubes (HCNTs) wrapped with reduced graphene oxide nanosheets (HCNTs/rGO) are successfully fabricated via a facile solution of self-assembly method, as well as a robust process for the simultaneous reduction and high N-doping of HCNTs/rGO composites (N-HCNTs/rGO) by photoreduction under NH3 atmosphere. The as-prepared N-HCNTs/rGO are directly employed as binder-free supercapacitor electrodes, and exhibit a highly conductive 3D-interconnected structure (5.85 S cm−1), large surface area (528.9 m2 g−1), low internal resistance (0.5 Ω), and good wettability. As a result, N-HCNTs/rGO show high specific capacitance (368 F g−1), high energy density (12.8 Wh kg−1), and cycling stability (90.7% retention at 1 A g−1 for 5000 cycles) in two-electrode systems. Moreover, the 3D N-HCNTs/rGO hybrid networks exhibit enhanced electrochemical performance in supercapacitors, which combine the synergistic effects of the two carbon nanostructures, enhanced wettability, low internal resistance, and improved ion-diffusion ability, together with the large surface areas of 3D hybrid networks and high-level N-doping. The as-synthesized composite is a potential candidate for flexible and binder-free electrodes for high-performance supercapacitors.