基于启发式概率Hough变换的道路边缘检测方法

针对非结构化道路的边界检测实时性和鲁棒性的难点,提出了加权Canny边缘检测方法和面向加权Canny边缘图像的启发式概率Hough变换方法;并根据非结构化道路边界不规则的特点和智能车辆路径规划的实际需求,提出了道路边界的双折线模型.与传统的方法相比,不同道路环境下的道路边界检测实验证明了所提算法的有效性和实时性.     

无结构P2P网络搜索方法及其改进

对等(P2P)计算是未来网络中的关键技术,对等网络是实现下一代互联网的重要组成部分。如何高效地搜索P2P网络上的资源是P2P网络实现的最为关键的问题。在讲述对等网络的基本搜索方法的基础上,分析了许多改进的搜索方法,包括基于转发的改进方法、基于缓存的改进方法和基于覆盖网拓扑优化的改进方法。     

传感器网络*

传感器网络作为连接真实的物理世界和虚拟的计算世界的桥梁,将引起人们越来越多的重视。首先介绍了传感器网络的概念及其应用,总结了其新的特征,分析了它对计算技术的挑战。在对传感器网络进行分类的基础上,探讨了非结构化传感器网络的设计方法;最后对目前传感器网络的研究热点进行了简要介绍。     

SUPNET: An end-to-end solution to scalable unstructured P2P networking

Despite many improvements on original unstructured P2P networks, these systems still suffer from several problems, the most important of which are, (a) lack of guarantees on the integrity of the network topology in the face of churns, (b) excessive traffic cost and (c) poor quality of search results. This paper introduces an end-to-end scalable unstructured P2P networking solution called SUPNET to address many of these issues. SUPNET is based on our pragmatic, design oriented approach to engineering complex networks. Rather than modeling dynamical behavior in already-existing networks, we actively design and implement local stochastic dynamics so that an engineered global system, with predictable structures emerges. The resulting protocol, SUPNET, consists of two sub-protocols for network management and content search. The network management sub-protocol is scalable and highly robust and is capable of utilizing the heterogeneous distribution of network resources. Its high stability is the result of implementation of a novel distributed feedback mechanism. The search sub-protocol is capable of locating every item, even if a single copy of that item exists in the network, while producing a traffic that scales provably sub-linear with the network size. It also contains mechanisms for very efficient location of popular items as well as distributed parameter tuning algorithms. These, along with inherently self-organized and de-centralized operation, relative ease of implementation and solid analytical foundation, make SUPNET a compelling solution for unstructured P2P networking.

风力机设计与数值模拟分析

在考虑叶尖损失和阻力影响诸因素的条件下,依据动量叶素理论设计了螺旋桨形风力机叶片,同时对设计结果在Gambit中建立数值计算模型,指定边界条件类型并划分网格,然后利用Flu-ent软件进行性能数值分析计算,给出风力机性能参数。     

非结构化环境中基于栅格法环境建模的移动机器人路径规划

以非结构化环境中移动机器人路径规划问题为研究对象,阐述了基于栅格法进行环境建模和基于人工势场法进行路径规划的思想及方法。基于MATALAB,通过边走边测和完全遍历两种策略的栅格法进行环境建模,使环境中的信息能够实时更新以保证环境模型的准确性,同时基于人工势场法进行路径规划。结果表明:在非结构化环境中,基于栅格法环境建模和人工势场法结合路径规划的方法规划出来的路径具有很好的实用性、合理性、实时性和环境变化适应性。     

Godunov-type upwind flux schemes of the two-dimensional finite volume discrete Boltzmann method

A simple unified Godunov-type upwind approach that does not need Riemann solvers for the flux calculation is developed for the finite volume discrete Boltzmann method (FVDBM) on an unstructured cell-centered triangular mesh. With piecewise-constant (PC), piecewise-linear (PL) and piecewise-parabolic (PP) reconstructions, three Godunov-type upwind flux schemes with different orders of accuracy are subsequently derived. After developing both a semi-implicit time marching scheme tailored for the developed flux schemes, and a versatile boundary treatment that is compatible with all of the flux schemes presented in this paper, numerical tests are conducted on spatial accuracy for several single-phase flow problems. Four major conclusions can be made. First, the Godunov-type schemes display higher spatial accuracy than the non-Godunov ones as the result of a more advanced treatment of the advection. Second, the PL and PP schemes are much more accurate than the PC scheme for velocity solutions. Third, there exists a threshold spatial resolution below which the PL scheme is better than the PP scheme and above which the PP scheme becomes more accurate. Fourth, besides increasing spatial resolution, increasing temporal resolution can also improve the accuracy in space for the PL and PP schemes.     

Guaranteed-Quality Simplical Mesh Generation with Cell Size and Grading Control

Unstructured mesh quality, as measured geo-metrically, has long been known to influence solution accuracy and efficiency for finite-element and finite-volume simulations. Recent guaranteed-quality unstructured meshing algorithms are therefore welcome tools. However, these algorithms allow no explicit control over mesh resolution or grading. We define a geometric length scale, similar in principle to the local feature size, which allows automatic global control of mesh resolution and grading. We describe how to compute this length scale efficiently and modify Ruppert’s two-dimensional and Shewchuk’s three-dimensional meshing algorithms to produce meshes matching our length scale. We provide proofs of mesh quality, good grading, and size optimality for both two- and three-dimensions, and present examples, including comparison with existing schemes known to generate good-quality meshes.     

知识发现状态空间模型研究及其应用

结构化数据挖掘与复杂类型数据挖掘既有联系,又有区别。如何将这两者统一起来,建立一个统一的理论框架,以指导数据挖掘与知识发现研完,已经成为一个迫切需要解决的问题。本文提出了知识发现状态空间统一模型UMKDSS,将结构化数据挖掘与复杂类型数据挖掘联系起来,为复杂类型数据挖掘提供理论指导。文章最后给出了UMKDSS在Web文本挖掘中的应用实例。     

Adjoint RANS with filtered shape derivatives for hydrodynamic optimisation

The adjoint RANS method has been implemented in the framework of an unstructured general-purpose finite volume code following the derive-then-discretise strategy (continuous adjoint approach). An explicit filtering technique is applied to the shape derivatives in order to extract noise from the mesh-based representation of high-resolution. In a CAD-free optimisation strategy the method is applied to a semi-circular profile in incompressible, external flow. It was observed that the filtering is particularly relevant at high Reynolds-numbers. In the complex scenario of ship hull design, the filtered shape derivative can directly be applied to the base-line configuration in order to support both manual and automatic shape optimisation.