reinforced concrete short column specimens with different polypropylene fiber contents. The depth of surface damage of the specimen was detected using ultrasonic method. The stress process and failure of the specimen were analyzed through axial compression test, and the corresponding changes in compressive toughness were discussed. A formula for calculating the axial compressive bearing capacity of polypropylene fiber reinforced concrete short columns after freeze-thaw cycles was established. The test results indicate that the addition of polypropylene fibers can reduce the compressive bearing capacity of reinforced concrete short columns. An appropriate amount of polypropylene fiber can enhance the frost resistance, ductility and toughness of concrete components, and the recommended volume fraction of polypropylene fiber is 0.08-0.12%.

single straight waveguide and the longitudinal section of coupling part of straight and annular waveguides are simulated according to the coupled-mode theory. The transfer matrix method is used to analyze characteristics between the length of the U-shaped feedback waveguide and the circumference of microring and the change of attenuation factor and coupling coefficient on the output spectrum. The simulation results showed that the embedded microring resonator with PtS2 as the core presents excellent optical properties. The resonance depth is more than –50 dB, and the sensitivity can reach 1806.61 dB/RIU. When the resonance wavelength is 1550.86 nm and the self-coupling coefficient is 0.9849. The corresponding detection limit is about 1.66056×10–7 dB/RIU, and the quality factor is 2.8848×10–5 under the measurement system with a signal-to-noise ratio of 30 dB. Compared with the traditional single microring structure, the proposed microring presents a higher free spectral range and more suitable for the fabrication of high-sensitivity, low-detection limit, and large-measurement range sensors.

on the pyramid data structure is proposed to complete the storage and calling of point cloud data. The improved bidirectional filtering algorithm is used to distinguish surface features quickly and obtain a 3D model of the site. Considering the characteristics of live working, the speed of data reading and querying, the nearest point search algorithm based on octree is used to acquire a real- time calculation of the safe distance of each point in the planned path, and the safety of the operation mode is obtained by comparing with the value specified in the regulation, and assist in making decisions of the operation plan. In the paper, the simulation of the actual working condition is carried out by taking the “the electric lifting device ascending” as an example. The experimental results show that the established three-dimensional model can meet the whole process control of the operation, and has achieved practical effect.

particle size, which is a key factor to the catalytic activity of Ni-Al2O3 catalysts for syngas methanation. Moreover, the relationship between Ni particle size and the production rate of methane per unit mass was correlated. The optimal Ni-Al2O3 catalyst prepared in ethanol at 2°C/min, achieves a maximum production rate of methane at the mean size of 20.8 nm.