In this paper; the surface plasmon resonance (SPR) sensor with a porous silica film was studied. The effect of the thickness and porosity of the porous silica film on the performance of the sensor was analyzed. The results indicated that the figure of merit (FOM) of an SPR sensor can be enhanced by using a porous silica film with a low-refractive-index. Particularly; the FOM of an SPR sensor with 40 nm thick 90% porosity porous silica film; whose refractive index is 1.04 was improved by 311% when compared with that of a traditional SPR sensor. Furthermore; it was found that the decrease in the refractive index or the increase in the thickness of the low-refractive-index porous silica film can enlarge the FOM enhancement. It is believed that the proposed SPR sensor with a low-refractive-index porous silica film will be helpful for high-performance SPR sensors development.

In this paper, we propose a surface plasmon resonance (SPR) sensor based on two-dimensional (2D) materials (graphene, MoS₂, WS₂ and WSe₂) hybrid structure, and theoretically investigate its sensitivity improvement in the visible region. The thickness of metal (Au, Ag or Cu) and the layer number of each 2D material are optimized using genetic algorithms to obtain the highest sensitivity for a specific wavelength of incident light. Then, the sensitivities of proposed SPR sensors with different metal films at various wavelengths are compared. An Ag-based SPR sensor exhibits a higher sensitivity than an Au- or Cu-based one at most wavelengths in the visible region. In addition, the sensitivity of the proposed SPR sensor varies obviously with the wavelength of incident light, and shows a maximum value of 159, 194 or 155°/RIU for Au, Ag or Cu, respectively. It is demonstrated that the sensitivity of the SPR sensor based on 2D materials’ hybrid structure can be further improved by optimizing the wavelength of incident light.

In this paper, we presented a design method of a surface plasmon resonance (SPR) biosensor with high performance using a genetic algorithm (GA). The constraint conditions of the sensitivity and the reflectivity at the resonance angle were used in the merit function (MF) of GA to achieve simultaneous optimization of the sensitivity and the resolution. By using the proposed method, we designed an Au-Ag-TiO₂-graphene based SPR biosensor at first and compared its performance with a traditional Au-graphene based SPR biosensor. The resolution of the designed biosensor was nearly three times that of the traditional one on the premise of the same sensitivity. In addition, a series of SPR biosensors with sensitivities ranging from 50 to 180°/RIU and improved resolutions was designed by using different target sensitivities in MF. A comparison of the designed biosensors with the traditional Au-graphene SPR biosensor was also done, and the biosensors with higher sensitivity and meanwhile higher resolution than the traditional one were demonstrated to be existed. Lastly, the influences of target reflectivity at the resonance angle and the prism on the design of the Au-Ag-TiO₂-graphene based SPR biosensor were investigated. It is believed that the proposed design method based on the genetic algorithm could be applied to optimize the performances of a SPR biosensor with an arbitrary multilayer structure.

This study has reviewed the emergency action and drainage process of the Xiaogangjian, Xiaogangjian-lower, and Yibadao cascade landslide dams that were formed during the 2008 Wenchuan earthquake in China’s southwest Sichuan Province. In order to minimize the hazards caused by the dam breach flood, mitigation works were carried out. Using underwater explosion and mechanical excavation, the dam heights of Xiaogangjian and Yibadao were lowered by 8 and 5 m, respectively. On June 12, the Xiaogangjian Dam was overtopped, followed by the failures of the two downstream dams, resulting in a flood with a peak discharge of $\mathrm{3,950}{\mathrm{m}}^3/\mathrm{s}$ measured at the downstream Hanwang gauge station. This paper describes the geographic and geotechnical features, mainly obtained from the field survey and laboratory testing. The back analysis on the breach flood is based on the authors’ work on Tangjiashan and Yigong barrier lakes. The results of this study show that the measured breach flood hydrograph can be reproduced using the currently available analytical methods if the input parameters related to the soil erosion and geotechnical properties are well determined based on experience and laboratory testing. The results of the analysis also show that the mitigation works of lowering the Xiaogangjian and Yibadao dam crest elevations effectively reduced the peak flow by nearly 20%.

Silver nanowires were used to enhance stimulated emission of Rhodamine 6G in a liquid random laser. Low-threshold coherent emission from the nanosecond-pulse-pumped random laser was achieved. Surface plasmonic resonance plays a key role in low-threshold operation of this random laser. The results demonstrate the ability of silver nanowires to enhance the stimulated emission, especially when the emission light from the dye molecules is far from the plasmonic resonance peak. Although the random laser shows different emission spectra in different directions, universal properties of strong interaction among multiple modes under different pump power densities were also demonstrated.