A compact and high-performance shielding enclosure designed by metamaterial structure based on frequency selective surface (FSS) is proposed. The enclosure has large holes for convenience of airflow and cable access. However, it can achieve great shielding performance by maintaining more than 40 dB attenuation. The shield is composed of n ×× n unit cells, and each unit cell is designed by knitting the 2.5-dimensional loop-type elements interconnected through vias. This design shows promising capability of size reduction, bandwidth expansion, and shielding effectiveness enhancement. Moreover, the enlarged holes on the FSS are helpful for the ventilation and heat dissipation. The size of the proposed 2.5-D FSS is only 0.097λ0λ0××0.097λ0λ0, where λ0λ0 corresponds to free space wavelength of resonance frequency. The proposed structure provides 3.38 GHz (3.21–6.59 GHz) wide shielding bandwidth. Furthermore, it has stable response to the wide-angle incident wave ranging from 0∘∘ to 85∘∘ with more than 40 dB attenuation at 4.83 GHz for both x-polarization and y-polarization. The proposed FSS is practically useful for the shielding of fifth generation (5G) wireless systems, WiMAX, and WLAN.

In order to identify and classify insects wing, a new identification algorithms of insects wing was presented in this paper. Wing image was divided into several grids in this algorithm, and according to the importance of the wing features based on every grid, targeted to set the weight for each grid and calculate the final similar, the result of comparison of wing features will be more comprehensive and accurate. Experimental results show that the proposed algorithm will be more accurate to compare wing features, and then identify the insect species.

No abstract

Airport crash fire vehicle simulator is an important device that is used in training of the airport firefighters, which has advantage of safe, energy saving and decreasing training cost. Sound system is an important part of airport crash fire vehicle simulator, which provides voice message to training personnel, which can make training personnel have immersed sense. Based on the principles of sound source position to analyze the different physical structure of the human body (head, torso, pinna) the impact of sound localization, the establishment of head-related transfer function model, using the model of the sound source, filtering, delay processing, and virtual sound source. And we have tested and verified with listening experiment.

Due to the diversity of landforms, an appropriate threshold should be selected for the simplification of different landforms. The distribution of simplified index was obtained by preprocessing the terrain data, and the distribution was used as a reference for threshold selection. In order to study the influence of terrain simplification on the prediction of complex electromagnetic environment, a visibility algorithm used in the regular model of terrain and a probability-based power propagation model are proposed. The visibility algorithm used in the regular model of terrain is based on the relationship between planes and triangular planes in three-dimensional space. The visible triangular surfaces and the corresponding visible area of the triangular surfaces in the terrain can be calculated with the visibility algorithm. The probability-based power propagation model uses the results of the visibility algorithm to calculate the propagation probability and calculates the change of receiver power in combination with the radio wave propagation characteristics. The spatial visibility algorithm and the probability-based power propagation model can be applied to the complex electromagnetic environment to analyze the influence of terrain simplification on prediction accuracy. The minimum error between the experimental result of the probability-based power propagation model and the Wireless InSite simulation result is 0.5018dB, and the average error is 1.5039dB.