In recent years,using message ferries as mechanical carriers of data has been shown to be an effective way to collect information in sparse wireless sensor networks.As the sensors are far away from each other in such ...In recent years,using message ferries as mechanical carriers of data has been shown to be an effective way to collect information in sparse wireless sensor networks.As the sensors are far away from each other in such highly partitioned scenario,a message ferry needs to travel a long route to access all the sensors and carry the data collected from the sensors to the sink.Typically,practical constraints(e.g.,the energy)preclude a ferry from visiting all sensors in a single tour.In such case,the ferry can only access part of the sensors in each tour and move back to the sink to get the energy refilled.So,the energy-constrained ferry route design(ECFRD)problem is discussed,which leads to the optimization problem of minimizing the total route length of the ferry,while keeping the route length of each tour below a given constraint.The ECFRD problem is proved to be NP-hard problem,and the integer linear programming(ILP)formulation is given.After that,efficient heuristic algorithms are proposed to solve this problem.The experimental results show that the performances of the proposed algorithms are effective in practice compared to the optimal solution.展开更多
This study introduced an automatic authentication technique for checking the genuineness of a vehicle. The rough set-based technique was used to handle the uncertainty arisen from artifacts in the acquired images impr...This study introduced an automatic authentication technique for checking the genuineness of a vehicle. The rough set-based technique was used to handle the uncertainty arisen from artifacts in the acquired images imprinted on a vehicle. However, it has been proved to be NP-hard to find all reductions and the minimal reduction, and generally different heuristic algorithms were used to find a set of reductions and the Ganssian distribution was used to describe the uncertainty to achieve the minimal reduction. On the basis of inductive logic programming, the technique can distinguish between two similar images, as is superior to the conventional pattern-recognition technique being merely capable of classifier. Furthermore, it can avoid some failures of the technique based on the correlation coefficient to authenticate binary image. The experiments show an accuracy rate close to 93. 2%.展开更多
This paper addresses the problem of accuracy characterization and measurement point planning for 3-D workpiece localization in the presence of part surface errors and measurement errors. Two frame-invariant functions ...This paper addresses the problem of accuracy characterization and measurement point planning for 3-D workpiece localization in the presence of part surface errors and measurement errors. Two frame-invariant functions of the infinitesimal rigid body displacement are defined to quantify the localization accuracy required by manufacturing processes. Then, two kinds of frame-invariant indices are derived to characterize the sensitivities of the accuracy measures to the sampling errors at the measurement points. With a dense set of discrete points on the workpiece datum surfaces pre-defined as candidates for measurement, planning of probing points for accurate recovery of part location is modeled as a combinatorial problem focusing on minimizing the accuracy sensitivity index. Based on an interchange rule, a greedy algorithm is developed to efficiently find a near-optimal solution. It is also shown that if the number of the measurement points is sufficiently large, there is no need to optimize their positions. Example confirms the validity of the presented indices and algorithm. Keywords localization - fixture - accuracy - uncertainty assessment - measurement planning - optimal design - heuristic algorithm展开更多
基金Projects(61272139,61070199,61103182)supported by the National Natural Science Foundation of ChinaProject(2013ZX01028001-002)supported by the National Science and Technology Major Projects of China+1 种基金Project(2011AA01A103)supported by theNational High-Tech Research and Development Plan of ChinaProject(11JJ7003)supported by Hunan Provincial Natural ScienceFoundation of China
文摘In recent years,using message ferries as mechanical carriers of data has been shown to be an effective way to collect information in sparse wireless sensor networks.As the sensors are far away from each other in such highly partitioned scenario,a message ferry needs to travel a long route to access all the sensors and carry the data collected from the sensors to the sink.Typically,practical constraints(e.g.,the energy)preclude a ferry from visiting all sensors in a single tour.In such case,the ferry can only access part of the sensors in each tour and move back to the sink to get the energy refilled.So,the energy-constrained ferry route design(ECFRD)problem is discussed,which leads to the optimization problem of minimizing the total route length of the ferry,while keeping the route length of each tour below a given constraint.The ECFRD problem is proved to be NP-hard problem,and the integer linear programming(ILP)formulation is given.After that,efficient heuristic algorithms are proposed to solve this problem.The experimental results show that the performances of the proposed algorithms are effective in practice compared to the optimal solution.
基金Sponsored by the National High Technology Research and Development Program of China (Grant No. 2003AA1Z2610)
文摘This study introduced an automatic authentication technique for checking the genuineness of a vehicle. The rough set-based technique was used to handle the uncertainty arisen from artifacts in the acquired images imprinted on a vehicle. However, it has been proved to be NP-hard to find all reductions and the minimal reduction, and generally different heuristic algorithms were used to find a set of reductions and the Ganssian distribution was used to describe the uncertainty to achieve the minimal reduction. On the basis of inductive logic programming, the technique can distinguish between two similar images, as is superior to the conventional pattern-recognition technique being merely capable of classifier. Furthermore, it can avoid some failures of the technique based on the correlation coefficient to authenticate binary image. The experiments show an accuracy rate close to 93. 2%.
基金the National Natural Science Foundation of China (Grant Nos. 50205018 , 50390063)the Key Basic Research Program of Shanghai Government (Grant No. 04JCI4050) the State Key Laboratory for Manufacturing System Engineering.
文摘This paper addresses the problem of accuracy characterization and measurement point planning for 3-D workpiece localization in the presence of part surface errors and measurement errors. Two frame-invariant functions of the infinitesimal rigid body displacement are defined to quantify the localization accuracy required by manufacturing processes. Then, two kinds of frame-invariant indices are derived to characterize the sensitivities of the accuracy measures to the sampling errors at the measurement points. With a dense set of discrete points on the workpiece datum surfaces pre-defined as candidates for measurement, planning of probing points for accurate recovery of part location is modeled as a combinatorial problem focusing on minimizing the accuracy sensitivity index. Based on an interchange rule, a greedy algorithm is developed to efficiently find a near-optimal solution. It is also shown that if the number of the measurement points is sufficiently large, there is no need to optimize their positions. Example confirms the validity of the presented indices and algorithm. Keywords localization - fixture - accuracy - uncertainty assessment - measurement planning - optimal design - heuristic algorithm
