A New Moving Kirchhoff-Love Plate Element for Dynamic Analysis of Vehicle-Pavement Interaction

A new moving Kirchhoff-Love plate element is developed in this work to accurately and efficiently calculate the dynamic response of vehicle-pavement interaction. Since the vehicle can only affect a small region nearby, the wide pavement is reduced to a small reduced plate area around the vehicle. The vehicle loads moving along an arbitrary trajectory is considered, and the arbitrary Lagrangian-Eulerian method is used here for coordinate conversion. The reduced plate area is spatially discretized using the current moving plate element, where its governing equations are derived using Lagrange's equations. The moving plate element is validated by different plate subjected to moving load cases, where the influences of different factors on reduced plate area length of the RBM model are also investigated. Then a vehicle-pavement interaction case with constant and variable speed is analyzed here. The calculation results from the moving plate element are in good agreement with those from the modal superposition method (MSM), and the calculation time with the moving plate element is only one third of that using the MSM. It is also found that the moving load velocity and ground damping have great influences on reduced plate area length of the RBM. The moving plate element is accurate and more efficient than the MSM in calculating the dynamic response of the vehicle-pavement interaction.

Stitching and Geometric Modeling Approach Based on Multi-Slice Satellite Images

Time delay and integration (TDI) charge-coupled device (CCD) is an image sensor for capturing images of moving objects at low light levels. This study examines the model construction of stitched TDI CCD original multi-slice images. The traditional approaches, for example, include the image-space-oriented algorithm and the object-space-oriented algorithm. The former indicates concise principles and high efficiency, whereas the panoramic stitching images lack the clear geometric relationships generated from the image-space-oriented algorithm. Similarly, even though the object-space-oriented algorithm generates an image with a clear geometric relationship, it is time-consuming due to the complicated and intensive computational demands. In this study, we developed a multi-slice satellite images stitching and geometric model construction method. The method consists of three major steps. First, the high-precision reference data assist in block adjustment and obtain the original slice image bias-corrected RFM to perform multi-slice image block adjustment. The second process generates the panoramic stitching image by establishing the image coordinate conversion relationship from the panoramic stitching image to the original multi-slice images. The final step is dividing the panoramic stitching image uniformly into image grids and employing the established image coordinate conversion relationship and the original multi-slice image bias-corrected RFM to generate a virtual control grid to construct the panoramic stitching image RFM. To evaluate the performance, we conducted experiments using the Tianhui-1(TH-1) high-resolution image and the Ziyuan-3(ZY-3) triple liner-array image data. The experimental results show that, compared with the object-space-oriented algorithm, the stitching accuracy loss of the generated panoramic stitching image was only 0.2 pixels and that the mean value was 0.799798 pixels, achieving the sub-pixel stitching requirements. Compared with the object-space-oriented algorithm, the RFM positioning difference of the panoramic stitching image was within 0.3 m, which achieves equal positioning accuracy.

Simplified Flat Coordinate Model for Northern Parts of Arabian Gulf

The method of coordinate conversion is still considered important and laborious due to the shift from the spatial ellipsoidal (geographic) to the flat planned system. The most common method uses a contiguous UTM system as one of the most reliable systems in the conversion process; however, this system faces a problem in large areas that contain more than one zone. The goal of this research is to create a simple and low computational cost model to represent a non-contiguous semi-UTM geographic coordinates for confined regions of the globe. The considered region taken in this study is the northern parts of Arabian Gulf (including parts of Iraq, Kuwait, Iran, and Saudi Arabia). The determined mathematical model was based on using two dimensional Taylor sequence. The most accurate representation met in this study was based on the 6th two dimensional polynomial. The estimation of equations’ coefficients was done using the least square criterion for the overall error of estimating coordinate values of either (latitude, longitude) or (Easting, Northing). The two basic determinations were applied for the forward and the backward; in the first step, the conversion of coordinates was calculated from the ellipsoidal coordinates (i.e., Longitude, Latitude) to UTM (WGS84) coordinates (i.e., Easting, Northing) and vice versa. The attained results indicated that the mathematical model used is successful for achieving the conversion process. With the use of the 6th order 2D-polynomial equations, a very small error of less than 1 m was achieved in the Easting and Northing coordinates.

A novel solution with rapid Voronoi-based coverage path planning in irregular environment for robotic mowing systems

This paper presents a novel solution of coverage path planning for robotic mowing applications. The planning algorithm is based on the Boustrophedon motions and the rapid Voronoi diagram. The coordinate conversion and the sweeping vector is defined by minimum bounding box and the Voronoi travel paths are designed to reduce the computational cost and execution time compared to conventional heuristic methods. The tracked path is controlled via dynamic feedback in standard lawn mowing robots under robot operating system (ROS). Within ROS, the information exchanging among different tasks of both extensive simulation cases and experimental field tests can be conducted easily. When meeting unknown obstacles, the proposed algorithm can re-plan its paths dynamically. The performance of the proposed algorithm is compared to several conventional coverage algorithms in terms of time efficiency, coverage, repetition, and robustness with respect to both concave and convex shapes. The field tests are conducted to demonstrate that the applicability of the sensor fusion and robustness of the proposed algorithm for the complete coverage tasks by robotic mowers.

A METHOD FOR MONITORING BULGE OF ANCIENT CITY WALL AFTER REPAIR

The ancient city wall is affected by factors such as environment and man-made factors, and the formed bulging disease is particularly prominent, and even caused irreversible damage to the ancient city wall. Therefore, the bulging monitoring after the repair of the city wall should be the top priority of the deformation monitoring of the city wall. This paper proposes a new plan for monitoring the bulge after the repair of the city wall. According to the point cloud data before the repair, the characteristic plane is fitted to determine the bulge range of the city wall, and then observation signs are placed on the surface of the repaired city wall at the corresponding location where the bulging deformation is severe. By using a total station to monitor the space coordinates of the observation signs, the deformations perpendicular to the wall can be obtained through coordinate conversion, and then the bulging of the repaired city wall can be determined. The actual application results show that this method can effectively monitor the swelling of the ancient city wall after the repair.