Main-lobe interrupted-sampling repeater jamming is a coherent type of interference. As this interference is injected through the main lobe of the antenna into a radar system, the interference heavily degrades the performance of the radar system. In this paper, we propose an anti-jamming method based on minimum variance distortionless response (MVDR) that estimates a covariance matrix by obtaining small-sample pure jamming signals through jamming recognition. Time-frequency analysis is performed in the one-dimensional range profile of the pulse-compressed radar echo, and the snapshot sampling of pure jamming is achieved by searching the range gates for the target and the jamming in a two-dimensional range-frequency graph considering the time-frequency differences between the target and jamming signals. Assuming that the available data of snapshot sampling are insufficient, a covariance matrix for pure jamming is reconstructed through an iterative adaptive approach (IAA) and used as the training sample for the MVDR beamformer to suppress main-lobe interrupted-sampling repeater jamming. Finally, the method is validated by comparing the simulation results with the measured results.

Distributed array radar can improve radar detection capability and measurement accuracy. However, it will suffer cyclic ambiguity in its angle estimates according to the spatial Nyquist sampling theorem since the large sparse array is undersampling. Consequently, the state estimation accuracy and track validity probability degrades when the ambiguous angles are directly used for target tracking. This paper proposes a second probability data association filter (SePDAF)-based tracking method for distributed array radar. Firstly, the target motion model and radar measurement model is built. Secondly, the fusion result of each radar’s estimation is employed to the extended Kalman filter (EKF) to finish the first filtering. Thirdly, taking this result as prior knowledge, and associating with the array-processed ambiguous angles, the SePDAF is applied to accomplish the second filtering, and then achieving a high accuracy and stable trajectory with relatively low computational complexity. Moreover, the azimuth filtering accuracy will be promoted dramatically and the position filtering accuracy will also improve. Finally, simulations illustrate the effectiveness of the proposed method.

In order to better evaluate the high-temperature performance of asphalt mixture, based on the conventional rutting test and Hamburg rutting test, this paper further studies the influence of temperature, grading and asphalt type on the high-temperature shear resistance of asphalt mixture by using uniaxial penetration test and uniaxial compression test. Based on Mohr Coulomb theory, the cohesive force and internal friction angle of mixture were calculated. Based on the analysis of variance, the significance of the influence of temperature and gradation on the high-temperature shear characteristics was studied. Linear regression analysis was used to reveal the correlation between the fractal dimension treated gradation and the shear resistance characteristics. Finally, the correlation between the high-temperature shear resistance performance index and the high-temperature rutting resistance evaluation index was analyzed. The results show that temperature has a significant effect on cohesion and internal friction angle of gradation pairs, and the fractal dimension Dc of coarse aggregate is positively correlated with cohesion and internal friction angle, with the strongest correlation. It indicates that the high-temperature performance of the mixture can be improved by increasing the passing rate of the sieve hole above 4.75 mm in the grading design. The correlation R2 between cohesive force index and high-temperature rutting resistance index of mixture at 35 ℃ is higher than 0.9, which belongs to extremely strong correlation. The shear resistance index of cohesion at 35 ℃ can be used to characterize the high-temperature rutting resistance of asphalt mixture.

According to the comparative analysis from the whole life cycle economic cost accounting, the capital investment of preventive maintenance of old cement concrete pavement is less than that of corrective maintenance. Based on the old cement concrete pavement, the problem such as anti-sliding noise, from how to improve the driving comfort and improve the stress of the cement road panel considering structure of old cement concrete pavement preventive maintenance are discussed in this paper, recommend a kind of cement concrete pavement noise reduction against sliding type ultra-thin rubber asphalt surface preventive maintenance structure, It can provide favorable technical reference for the applicability and rational selection of preventive maintenance structure of old cement concrete pavement.