数字线划图(DLG)管理系统研究与开发

通过分析数字线划图数据目录文件管理方式的缺点,提出了利用数据库管理数字线划图数据的思路.结合实际应用给出了数据库设计,采用AutoCAD+SQL Server模式开发了数字线划图管理系统,应用效果显著.     

Confined spaces path following for cable-driven snake robots with prediction lookup and interpolation algorithms

While cable-driven snake robots are promising in exploring confined spaces, their hyper-redundancy makes the collision-free motion planning difficult. In this paper, by combining the prediction lookup and interpolation algorithms, we present a new path following method for cable-driven snake robots to high-efficiently slither into complex terrains along a desired path. In our method, we first discretize the desired path into points, and develop the prediction lookup algorithm to efficiently find the points matched with joints of the robot. According to geometric relations between the prediction lookup results and link length of the robot, we develop the interpolation algorithm to reduce the tracking errors caused by the discretization. Finally, simulations and experiments of inspections in two confined spaces including the obstacle array and pipe tank system are performed on our custom-built 25 degree of freedoms (DOFs) cable-driven snake robot. The results demonstrate that the presented method can successfully navigate our snake robot into confined spaces with high computational efficiency and good accuracy, which well verifies effectiveness of our development.     

A moment-based stochastic edge-based smoothed finite element method for electromagnetic forming process

In this paper, a novel stochastic method named as the moment-based stochastic edge-based finite element method(MSES-FEM)is proposed to deal with the uncertain electromagnetic problems. First, electromagnetic and mechanical field are formulated by smoothed Galerkin Weak Form under edge-based smoothed finite element method(ES-FEM) scheme. The moment analysis is then applied to obtain the first four moments of the responses and to observe the effects of each random variable on electromagnetic field responses. The maximum entropy theory is employed to calculate the probability density functions(PDFs) of the responses. A quasi-static electromagnetic problem and a practical electromagnetic forming problem(EMF) are performed. The proposed method successfully solves stochastic electromagnetic forming analysis under the uncertain parameters. Numerical results obtained by the proposed MSES-FEM are quite satisfactory with the ones by the Monte Carlo simulation(MCS).     

Relay-assisted hierarchical adaptation scheme for multi-user scalable video delivery to heterogeneous mobile devices

In multi-user video (MUV) delivery scenarios,the available resources of receiver devices,such as processing capability,link packet error rate (PER),and bandwidth,are usually different.We propose a relay-assisted hierarchical adaptation (RHA) scheme to maximize the total perceptual quality of all users when transmitting video streams coded via scalable video coding (SVC).First,MUV bitstreams are adaptively extracted under the constraints of network bandwidth and individual decoding capacity.Next,the relay links are introduced as substitutes of possible bad direct links for packets retransmissions.Approximately equal opportunity of transmission is allocated to each stream while the packets inside a stream are scheduled according to their priorities.The priorities are determined by the links states and packets loss distortions.Simulation results show that our RHA scheme has significant performance improvements compared with other schemes.