In this study, a series of new concepts and improved genetic operators of a genetic algorithm (GA) was proposed and applied to solve mobile robot (MR) path planning problems in dynamic environments. The proposed method has two superiorities: fast convergence towards the global optimum and the feasibility of all solutions in the population. Path planning aims to provide an optimal path from a starting location to a target location, preventing collision or so-called obstacle avoidance. Although GAs have been widely used in optimization problems and can obtain good results, conventional GAs have some weaknesses in an obstacle environment, such as infeasible paths. The main ideas in this paper are visible space, matrix coding and new mutation operators. In order to demonstrate the superiority of this method, three different obstacle environments have been used and an experiment is conducted. This algorithm is effective in both static and dynamic environments.
Six concrete beam-column frame sub-assemblages reinforced with basalt fiber-reinforced polymer (BFRP) bars in the frame beams were designed to investigate the collapse resistance after a middle column removal. Effect of parameters, including span to depth ratio of frame beams, prestressing, as well as material types of stirrups in the beams, on the collapse resistance of the sub-assemblages, was investigated. Experimental results showed that the initial stiffness of the frame beams was apparently lower due to low elastic modulus of BFRP bars. The collapse resistance of the sub-assemblages presented wave-like increasing tendency with the vertical displacement of the failed middle column, and it mainly attributed to the cracking or crushing of concrete and rupture of BFRP bars in the frame beams. Top longitudinal BFRP bars at the beam ends near to the side column (BESCs) and bottom longitudinal BFRP bars at the beam ends near to the middle column (BEMCs) kept tensile during the loading process, which played an important role in resisting structural collapse. Adjacent structural members such as frame beams and columns could provide horizontal reaction forces to constrain the free deformation of the residual sub-assemblages after the middle column failed, and it was beneficial to mitigate the structural collapse risk. The vertical deformation of the frame beams was nearly linear and proportional to the vertical displacement of the failed middle column. Finally, the dynamic increase factor (DIF) of collapse load was discussed using energy conservation method, and a calculation method of DIF for prestressed concrete frame structures was developed. It was suggested that the DIF values for the non-prestressed frame structures reinforced with BFRP bars in the beams should be taken as 2.0, while those for the prestressed sub-assemblages can be taken between 1.44 and 2.0.
The subpixel imaging system with line-array CCD sensors and with area-array CCD sensors are introduced in the past paper.The system is consisted of a high-resolution lens, a beam splitter and two line-array CCD sensors or four area-array CCD sensors with subpixel displacements in the focal planes. In order to get a high spatial resolution in the pushbroom direction for pushbroom imaging system, the sample spacing between line images is decreased. Processing the original images got through the subpixel imaging system specially, a new image with higher spatial resolution could be constructed. The imaging system will be suitable for space application because the configuration is stable and rugged. The key techniques involved in the subpixel imaging system are the followings: (1) the precision measuring technique ofthe CCD sensors' location and (2) the technique ofthe new image constructing.Key works: Subpixel imaging, High resolution imaging, CCD camera, Optical remote sensing . INTRODUCTIONUtilizing the subpixel imaging technique is effective to enhance the spatial resolution of optical instruments. The technique is useful to reduce the effective focal length of optical system while keeping the same spatial resolution. Using the method, the weight and volume ofoptical remote sensors will be decreased greatly.The method presented in the paper is to insert a beam splitter between the lens and the sensors in an imaging system. Two images are obtained simultaneously by the imaging system for moving scenes. Processing these images specially, a new image is constructed with twice the original resolution. Comparing with the past techniques"2'3, the new one will be suitable for the imaging and measuring of the moving targets and enhances the resolution apparently. The CCD sensor with smaller photoelement size and more elements is difficult to fabricate and the cost is high. It is effective in the high resolution imaging with the line-array CCD sensors of low cost and high response.The imaging system will be suitable for space application because the configuration is stable and rugged. Miniaturizing the optical remote sensors will be realized using the presented method. In order to achieve the exact sensor placement required, the sensor placement must be controlled to within 5% ofthe gross pitch. The key techniques involved in the subpixel imaging system are the followings: (1) the precision measuring technique of the CCD sensors' location and (2) the technique of the new image constructing. Imaging registration is a fundamental task in image processing to overlay two or more images used.
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