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We consider the problem of navigation and guidance of a wheeled mobile robot towards a maneuvering target based on the measurements concerning only the distance from the robot to the target. We propose a sliding mode controller that drives the robot to the predefined distance from the target and makes the robot follow the target at this distance. Mathematically rigorous proof of convergence and stability of the proposed guidance law is presented. Simulation results confirm the applicability and performance of the proposed guidance approach. 相似文献
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We consider the problems of a wheeled mobile robot navigation and guidance towards an unknown stationary or maneuvering target using range-only measurements. We propose and study several methods for navigation and guidance termed Equiangular Navigation Guidance (ENG) laws. We give mathematically rigorous analysis of the proposed guidance laws. The performance is confirmed with computer simulations and experiments with ActivMedia Pioneer 3-DX wheeled robots. 相似文献
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The problem of developing a reliable system for sensing and controlling the hover of a Micro Air Vehicle (MAV) using visual snapshots is considered. The current problem is part of a larger project, which is developing an autonomous MAV, controlled by vision only information. A new algorithm is proposed that uses a stored image of the ground, a snapshot taken of the ground directly under the MAV, as a visual anchor point. The absolute translation of the aircraft and its velocity are then calculated by comparing the subsequent frames with the stored image and fed into the position controller. In order to increase the performance, several issues, such as effects of scale uncertainty on the closed loop stability of the platform are investigated. For controller design and testing purposes, we analytically derive a complete model of a small size helicopter with no stabilizing bar (flybar). The simulation results for 2D and 3D snapshots confirm the effectiveness of the proposed algorithm. 相似文献
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We consider a single Dubins-like vehicle traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A sensor provides the distribution value at the vehicle location. We present a new sliding mode control method for tracking environmental level sets: the vehicle is steered to the set where the distribution assumes a pre-specified value and circulates along this set afterwards. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous justification is provided. The effectiveness of the proposed guidance law is confirmed by computer simulations. 相似文献
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Fe2O3/TiO2/activated carbon (FT/AC) nanocomposites supported on silica gel beads were synthesized using a sonochemical method and fully characterized. The response surface method was applied to optimize the removal of Pb(II) ions by nanocomposites under visible light. The experiments were conducted by adjusting three parameters, i.e., initial concentration of Pb(II) ions, dosage of Fe2O3/TiO2 (FT) photocatalyst, and pH. The FT/AC nanocomposite showed higher efficiency for Pb(II) ion removal in comparison with FT due to the synergistic effect of activated carbon combined with Fe2O3/TiO2. 相似文献
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Multimedia Tools and Applications - In this paper, we propose a new segmentation method for diarization applications. In the proposed method, segmentation is performed using a discriminatively... 相似文献
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We present a sliding mode based method for a unicycle-like vehicle control and guidance. The proposed guidance-control law is applied to the problems of border patrolling and obstacle avoidance. A mathematically rigorous analysis of this law is provided. 相似文献
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Ahmad Teimoori Zhixi Chen Sheik S. Rahman Thanh Tran 《Petroleum Science and Technology》2005,23(5):693-709
A model is presented to calculate the effective permeability tensor in naturally fractured reservoirs using Boundary Element Methods (BEM). Arbitrary fractures of different scales based on their length are considered. Interface boundary condition is used to model the short fractures as an enhancement of matrix permeability. Long fractures, on the other hand are treated as source/sink in the corresponding blocks. Periodic boundary condition is applied to the grid-block boundaries to calculate the elements of effective permeability tensor. Darcy's law and Navier-stoke's equation are applied to fluid flow in rock matrix and fractures, respectively. An important feature of this approach is that the fluid flow in matrix-fracture interface is coupled by Poisson's equation and fluid flow in the rest of the matrix is formulated by Laplace's equation. This paper also presents an innovative approach to optimization and parallelization of the model by High Performance Computing (HPC) techniques. The model has been validated against analytical results and applied to a typical case where arbitrary fractures of different sizes are assumed within the grid blocks. The effective block permeability tensors can be implemented into a reservoir simulator to calculate fluid flow through the naturally fractured reservoirs. 相似文献
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The impact of nonpolar coagulation bath‐immiscible liquid additives on the polyethersulfone membranes structure and performance
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Mostafa Teimoori Seyed Abdollatif Hashemifard Ahmad Fauzi Ismail Mohsen Abbasi 《应用聚合物科学杂志》2017,134(8)
In this study, the impact of several normal alkanes as additives on the structural parameters and the morphologies of flat sheet PES membranes were investigated. The asymmetric membranes were fabricated by phase inversion method. Also n‐hexane, n‐decane, and n‐tetradecane were used as additives. The effects of different concentrations of these additives were investigated by producing the ternary phase diagrams. Further the membranes were characterized by means of solute transport test, contact angle, pure water flux, porosity measurement, and scanning electronic microscopy. It was expected that two distinct phase inversions to be occurred since both the polymer and the additives were insoluble in the coagulation bath. Observations revealed that n‐hexane and n‐decane were less effective compared with n‐tetradecane in terms of binodal shifting toward PES/NMP axis. In conclusion, it was revealed that the coagulation bath immiscible‐liquid additives had a major impact on the membranes structure in order to achieve the enhanced properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44509. 相似文献