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The crack detection algorithm based on Bilateral-Frangi filtering can effectively reduce the influence of noise on the crack detection results at the bottom of the bridge.This algorithm effectively removes noise while enhancing cracks at the bottom of the bridge.Through this algorithm,the data analysis results are more accurate.This effectively provides a new idea for crack detection in high-noise images.

Traditional data analysis methods and methods are difficult to effectively mine and analyze a large number of Rail Geometry state data, which makes the value of data cannot be fully utilized and played. Based on this, this paper first analyses the characteristics of railway track geometric irregularity, then studies the BP neural network prediction method and steps of railway track geometric irregularity, and gives its prediction effect.

Wide frequency range and high acceleration amplitude are two typical characteristics of transient vibration in the environment of pyroshock on spacecraft. The Piezoelectric accelerometer is widely accepted as the best available transducer for the absolute measurement of vibration. “Ringing” and “Zero Drift” are very easily to occur if the accelerometer is being used to measure transient vibrations outside its useful frequency range. This paper introduced the working principle of piezoelectric accelerometer, The scheme of reducing “Ringing” phenomenon was given, The mechanism of “Zero Drift” phenomenon was analysed. The methods to restrain the “Zero Drift” were discussed from the aspects of the selection of test equipment, the installation of piezoelectric accelerometer and the setting of data acquisition parameters. Finally, the wavelet analysis method was used to decompose and reconstruct the distortion data caused by “Zero Drift”, and the effective pyroshock response signal was extracted.

China Space Station (CSS) module is currently under construction. Considering astronauts will be working and living on orbit for several months, a comfortable acoustic environment in manned space station must be provided. This paper investigates the interior noise effects for CSS using two typical vibro-acoustic analysis methods, that is, coupled finite element/finite element method (FE/FEM) and statistical energy analysis (SEA) method. The simulation models are validated through ground experiments by the noise test for space station simulation module. The combination of the above two methods can well predict the acoustic levels for both low and high frequencies. A ground experiment scheme for interior noise of space station module is also proposed on the basis of its noise characteristics. Sound power equivalent method is utilized to simulate a single noise source and multi-input multi-output (MIMO) closed-loop control method is employed for multiple noise sources. It is shown that the sound field simulation results are in perfect agreement with the simulation requirements of noise sources.

Controlled release system has been widely developed and used in agriculture to improve efficacy and minimize environmental pollution. Here, the pesticide-loaded carboxymethyl chitosan microspheres were constructed by suspension-crosslinking method. Carboxymethyl chitosan was used as a carrier to formulate microsphere to load neonicotinoids with a mixture of calcium chloride and glutaraldehyde as double-component cross-linking agent. The resulting microsphere processed high drug loading and encapsulation efficiency with a mean diameter of 1 mm. The UV detection method of pesticide was established, which was convenient and quick. The pesticides release properties of the microspheres were investigated, and the controlled release time was more than 6 days, which achieves the objective of improving the efficacy of the pesticides. This work would promote the development of controlled-release pesticide systems.

In recent years, Unmanned Aerial Vehicles (UAV), have been increasingly utilized by scholars. Efficient control of UAV swarms opens a set of new challenges. There are several formation control methods, however, artificial potential field (APF) method has imperfections in formation maintaining and virtual structure is insufficient in collision avoidance. In this paper, we proposed a multi-UAV formation maintaining method combined artificial potential field method and virtual structure approach. The method uses the concepts of attraction and repulsion in the artificial potential field method, combined with formation reference points inspired by the virtual structure points in the virtual structure approach to control the formation. On the other hand, we express the leaders, the followers, and the formation reference points uniformly. When the formation of UAVs is determined, after the leader arrives at target point and hovers, the followers can track the formation reference points. The method can avoid collision between UAVs and achieve the purpose of formation maintaining. Finally, a UAV swarm consists of four UAVs is used for demonstration and verification, and the results of experiment prove the validity of the algorithm.

The previous work on nanocomposites containing silica nanoparticles has indicated that when a relatively high silica nanoparticles content is used, reinforcing effect of that weakens due to the formation of agglomerates of nanoparticles within the polyurethane matrix. Therefore, in this paper, shear thickening fluid-enhanced polyurethane foams were synthesized to resolve such problems. Because hydroxyl groups can form hydrogen bonds with some polar molecules, several layers of molecules in PEG-400 can be adsorbed on the surface of silica nanoparticles. The silica nanoparticles could be dispersed in that polymer matrix very well and surface energy of silica nanoparticles decreases. The comparative study of polyurethane foam (PUF) composites based on shear thickening fluid (STF) had been reported. A wt%-dependent SEM analysis was carried out to understand the effects of STF on the cell morphologies of STF PUF. The linear viscoelastic properties of polymer matrix with STF was characterized by parallel plate rheometer. Finally, the mechanical properties were investigated. The results indicated that when the content of shear thickening fluid is more than 7.5%, the synergistic effect of SiO2 with PEG-400 on enhanced PUF was a major cause of improvement of its mechanical properties.

This paper mainly studies the effect of shear thickening gel on the impact resistance of polyurethane foam. First, flexible polyurethane foams with strain rate sensitivity, shape memory, and impact resistance were prepared by a convenient one-step foaming method. Then, the surface morphology and impact resistance of the composites were characterized by SEM, AFM, and low-velocity impact tests. The results demonstrated that the addition of the shear thickening gel makes the cell size of the composites more uniform and the molecular chain arrangement more regular. When the amount of the shear thickening gel was 20 parts, the surface roughness of polyurethane foams was increased from 14.7 to 74.7 nm. More importantly, the addition of the shear thickening gel significantly enhanced the impact resistance of polyurethane foam. When the impact velocity was 5.5 m s−1, the ratio of absorbed energy to impact energy of the FPUF-15pbw reached 91.35%, which was 20.12% higher than the FPUF-0pbw.

The reserves of coalbed methane (CBM) in China are very high. But the characteristics of “three low” (low pressure, low permeability, low porosity), thin formation and shallow burial depth for the CBM reservoirs may cause problems of long production cycle and slow increase in production. For above problems, a new reconstruction method for coal bed methane formation named underbalance reconstruction was introduced. By this method, a jet generator was lowered to perforated interval. Then, with the nitrogen injected and blowout, reconstruction results of coalbed reservoir can be achieved. Considered the process of underbalance reconstruction, coalbed reservoir properties and mechanical properties of coalbed, mechanical model of coalbed methane well was built and analyzed by finite element method. Afterwards, damage area of different nitrogen injecting cycle can be characterized. And the effect of underbalance reconstruction for coal bed methane formation can be obtained. Then, parameters of reconstruction technology can be optimized and optimization scheme can be supplied for the underbalance reconstruction for coal bed methane formation.