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This paper proposed a V-shaped metamaterial absorber to enrich the structure of the absorber and improve its absorbing efficiency. The structure is to print an inclined V-shaped copper-plated layer on the FR4 substrate and arrange them periodically. The absorber has two large absorption peaks, and the bandwidth with an absorption rate of more than 90% is 1.3 GHz. The origin of absorption mainly comes from reflection cancellation, followed by dielectric loss. The basic type of V-shaped absorber has excellent promotion space and application prospects. It can further optimize and expand the performance of absorber through three main forms: unit nesting, multi-unit array and multi-layer stacking. Based on the structure of unit nesting combination, the processing of experimental samples and the measurement of electromagnetic parameters were completed. The experimental results are in good agreement with the simulation results.

The nitrate ester plasticized polyether (NEPE) propellants were accelerated aged at 65, 70, and 75 °C, respectively. The dynamic mechanical properties of NEPE propellants were determined with the dynamic mechanical analysis method. The strength limit of NEPE propellants was tested by the uniaxial tension test. The relaxed modulus and strength limit both decreased. By calculating the structural integrity of NEPE grain, the effects of modulus changes on the structure integrity were analyzed. The results provide a reference for the life prediction of solid rocket motor containing an NEPE propellant.

The detection probability for a moving target is an important issue, we aim to discuss the detection probability for a moving ground target such as military vehicles using a visible light imaging satellite. First, a basic detection model for a regional ground target using a satellite was discussed and the probability of detection was calculated. Next, a basic model for the recognition of a ground target using a visible light imaging satellite was developed based on above model. Then, a basic model of the detection probability for a moving ground target using a visible light imaging satellite was studied. As the normal distribution has the maximum entropy, the normal distribution of a moving ground target such as military vehicles was analyzed, and based on our conclusions, a basic probability model for the detection of a moving ground target using a visible light satellite was developed. Finally, the simulation was carried on.

In the fault diagnosis of gearbox, the extraction of the characteristic currently, usually suppose that vibration signal fault signal is a key problem. The practical testing vibration is acquired on constant duty and unchanged circumstance, and signal of gearbox is no stable or Gauss distributing. In different have the characteristic of stability and Gauss distributing. In fault states, the vibration signal has different Gauss property and fact, in engineering, much mechanical equipment usually runs symmetry property, usually including stronger noise and low '' .SNR. Faint fault information is often totally flooded in the noise, n siftion anar duty. So th practi eca nical, so it is very difficult to extract the signal characteristic. Because viatio sign mostly blns to non-stead si signal's Higher-order cumulant is not sensitive to the adding especially even more like this while breaking down, but just Gauss noise and symmetry non-Gauss noise, if applied in the stability under meeting certain special condition fault diagnosis of the gearbox, it can separate signal and noiseIn the fault diagnosis of gearbox, the extraction of the fault effectively, improve the SNR and intensify fault information.signal is a key problem. The practical testing vibration signal Based on the contrast and analysis of the vibration signal of some of gearbox is no stable or Gauss distributing. In different fault second gearbox under different states, this paper has extracted states, the vibration signal has different Gauss property and the power spectrum and Higher-order cumulant spectrum symmetry property, usually including stronger noise and low (bispectrum) of the gear vibration signals, has set up the SNR. Faint fault information is often totally flooded in the characteristic vector of bispectrum used in fault diagnosis. The noise, so it is very difficult to extract the signal characteristic.analysis result shows that, compared with power spectrum, the Two-order cumulant spectrum (the power spectrum) is the characteristic extracting from the Higher-order Cumulant commonly analysis method of gear fault signal. The frequency spectrum is more sensitive to the fault characteristic, and easy to spectrum difference of vibration signal under the normal and realize the digital characteristic extracting in the intelligent fault state can distinguish the working state of gearbox, thus diagnosis, can identify the fault of gearbox effectively, the fault can be diagnosed. Theoretically, the power spectrum Keywords: gearbox, vibration signal, Higher-order cumulant of the signal is sensitive to the colored noise; it can't offer the spectrum. effective means to separate the primitive signal and noise. Xu Jinwu, etc. take use of the method of matrix fantastic spectrum 1. INTRODUCTION characteristic of reconstruct attractive particle orbit and wavelet transform to reduce the noise, so the fault As a kind of shifting and power transferring common characteristic of vibration signal is intensified [2,3]. While this equipment, because of its compact stru...