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Pile-plank structures are widely applied for high-speed railway built in soft ground in China. It can be used as a reinforcement to improve the behavior of subgrade by providing vertical confinement to increase their stiffness and strength and reduce the subgrade settlement of ballastless track. However, the use of pile-board structure for soft ground reinforcement of high-speed railway is hindered by the existing gap between applications and theories. To verify vibration characteristics and long-term performance of pile-plank-supported low subgrade of ballastless track and the benefit of pile-board structure, an experimental study was conducted on low subgrade of pile-board under excitation loads using both in situ frequency sweeping and cyclic loading experiments. The frequency sweeping experimental results show that the pile-plank-supported low subgrade has smooth stiffness along the longitudinal subgrade and can effectively control the progressive effects of train speed on dynamic stiffness of the subgrade, which ensures driving safety and comfort. The cycle loading experimental results show that the pile-plank-supported low subgrade has favorable long-term dynamic stability, and its dynamic response is uniform along the longitudinal subgrade.

In the study of three-dimensional underwater sensor networks, the nodes would produce changes in perception range under the influence of environmental factors and their own hardware. Requesting all nodes completely isomorphic is unrealistic. Ignoring boundary effects usually causes the coverage effect of the actual deployment of networks to not reach the anticipated result. This paper firstly presents an underwater sensing model with normal distributed node sensing radius. Secondly, it gives the relationship between expected deployment quality and the number of nodes in the premise of considering boundary effects. Then, it deduces nodes’ redundancy formula based on the sensing model with normal distributed node sensing radius, making node could determine whether itself is a redundant node only based on the number of its neighbour nodes. Furthermore, this paper proposes a redundancy model and boundary effects based coverage-enhancing algorithm for three-dimensional underwater sensor networks (RBCT). Simulation results show that RBCT, compared to similar algorithms, has certain advantages in saving energy and enhancing coverage rate.

This study develops a mesoscopic framework and methodology for the modeling of microcracks in concrete. A new algorithm is first proposed for the generation of random concrete meso-structure including microcracks and then coupled with the extended finite element method to simulate the heterogeneities and discontinuities present in the meso-structure of concrete. The proposed procedure is verified and exemplified by a series of numerical simulations. The simulation results show that microcracks can exert considerable impact on the fracture performance of concrete. More broadly, this work provides valuable insight into the initiation and propagation mechanism of microcracks in concrete and helps to foster a better understanding of the micro-mechanical behavior of cementitious materials.

Aimed at the defects of current coverage-enhancing algorithms, firstly the probability model is introduced into the coverage-enhancing algorithm of the directional sensor network based on the virtual potential field, and the probability model would have an impact on the location of the centroid. Secondly, to the boundary coverage, through the simulation of typical algorithms which consider the boundary repulsion, it finds that the coverage rates of the corners are much lower than the overall coverage. To add a vertex force on the corner is essential and to some extent would reduce the gap between them. Finally, based on the random deployment of sensor nodes, a novel algorithm is proposed which determines whether the sensor node rotates or moves along fixed direction according to the coverage effect, named as PRMCA (probability model based rotate or move along fixed direction coverage-enhancing algorithm). A set of simulation experiments verify the performance of the proposed algorithm.

In conventional directional sensor networks, coverage control for each sensor is based on a 2D directional sensing model. However, 2D directional sensing model failed to accurately characterize the actual application scene of image/video sensor networks. To remedy this deficiency, we propose a 3D directional sensor coverage-control model with tunable orientations. Besides, a novel criterion for judgment is proposed in view of the irrationality that traditional virtual potential field algorithms brought about on the criterion for the generation of virtual force. Furthermore, cross-set test is used to determine whether the sensory region has any overlap and coverage impact factor is introduced to reduce profitless rotation from coverage optimization, thereby the energy cost of nodes was restrained and the performance of the algorithm was improved. The extensive simulations results demonstrate the effectiveness of our proposed 3D sensing model and IPA3D (improved virtual potential field based algorithm in three-dimensional directional sensor networks).

The photocatalytic inactivation effecting of gold-doped TiO2 (Au/TiO2) nanocomposites on human colon carcinoma LoVo cells was investigated for the first time. The Au/TiO2 samples containing different amounts of Au (1–4 wt%) were prepared by deposition-precipitation (DP) method. These synthesized Au/TiO2 nanocomposites were characterized by transmission electron microscopy (TEM) and inductively coupled plasma atomic emission spectroscopy. It was found that the photocatalytic inactivation effect of TiO2 nanoparticles on LoVo cancer cells could be greatly improved by the surface modification of Au nanoparticles. Furthermore, the loading amount of Au on the surface of TiO2 nanoparticles affects the photocatalytic inactivation efficiency strongly, and it was found that the most efficient nanocomposites were TiO2 nanoparticles doped with 2 wt% Au. When 50 μg/mL 2 wt% Au/TiO2 nanocomposites were used, all of the LoVo cancer cells were killed under the irradiation of UV light (λmax = 365 nm, Intensity = 1.8 mW/cm2) within 100 minutes. But for 50 μg/mL TiO2 nanoparticles, only 40% cancer cells were killed under the same condition.