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Underwater Wireless Sensor Networks (UWSNs) have emerged as a critical component within underwater distributed perception applications. Due to the external factors, including ocean currents and undulating seabed topography, the UWSNs topology that changes dynamically over time cannot ensure optimal service performance. This paper proposes a balancing energy consumption and localization through coverage (BECLC), which adjusts the position of drifting underwater nodes through improved virtual forces, and achieves improvements in node energy consumption as well as localization accuracy. Firstly, the UWSNs coverage problem is modeled as a virtual force problem involving underwater nodes, underwater relay nodes, and obstacles, which can guide densely or sparsely dispersed underwater nodes to suitable locations under the action of joint virtual forces. Next, considering that the underwater relay node needs to consume more energy in the process of forwarding more data, the non-uniform deployment combined with hierarchy routing is proposed to reduce the coverage holes caused by node energy exhaustion. Finally, with regards to the drifted coordinates and noisy ranging of uncertain measurements, the theoretical localization performance of underwater target is evaluated with use of Cramer-rao lower bound as a benchmark. The experimental results show that proposed method not only enhances the coverage rates, but also prolongs the network surviving time and improves the localization accuracy in UWSNs.

The objective of this research was to develop a solution for the deterioration effect on the high-temperature rutting performance and water stability of SMC. This research proposed a method for designing an SMC normal temperature modified asphalt mixture based on the existing findings, experimental research and the performance balance. First, the power function curve model of the aggregate gradation was put forward. The 0.075 mm, 4.75 mm and nominal maximum particle size were the key points of the aggregate gradation, and their passing rate was about 6%, 30%, and 95% respectively. Then, on the basis of the quadratic curve model, a method for determination of the optimum asphalt aggregate ratio of SMC normal temperature modified asphalt mixture was put forward, considering the skeleton-density structure. Last, rutting tests, small beam bending tests, freeze-thaw split tests, permeability coefficient tests, texture depth tests and pavement roughness tests were conducted, and the test results all met the performance requirements of the specifications for the construction of highway asphalt pavement in China perfectly, especially the high-temperature and water stability properties, which indicated that the design method for SMC normal temperature modified asphalt mixtures based on performance balance presented in this paper was reasonable and practical. [ABSTRACT FROM AUTHOR]

Mastic asphalt is a type of pavement material that has good fluidity and is self-levelling at construction temperature for the bridge deck. There are highly accurate methods and indexes for evaluating fluidity and high-temperature deformation resistance for mastic asphalt-design and construction-control systems. The fatigue cracking is one of the main failure forms of bridge deck pavement. Therefore, the method used to evaluate the fatigue properties of pavement materials is also essential. The anti-deformation capability of the mastic asphalt must be increased, that results in poor fatigue performance and consequent failure of the bridge deck pavement to avoid the rutting of bridge deck pavement. In this study, a simple method is put forward for evaluating mastic asphalt fatigue performance. Impact toughness is defined as the area under the load-displacement curve of a three-point bending beam specimen under impact load to evaluate the fatigue performance of mastic asphalt. The four-point bending beam fatigue test is used to verify the rationality of the impact toughness test method. The results showed that there is a good correlation between the impacts toughness index of mastic asphalt produced under different mixing conditions and the accumulative dissipative energy and fatigue life demonstrated by the four-point bending beam test. Therefore, to evaluate the fatigue performance of mastic asphalt by impact toughness test. Fatigue performance and rut resistance are two ways to evaluate road performance of asphalt mixtures, but they are mutually restrictive. The results show that impact toughness and dynamic stability are inversely correlated. As the impact toughness increases, dynamic stability decreases. Therefore, balancing the fatigue performance and high-temperature rutting resistance of mastic asphalt in the design and quality control is very important.