Evacuation travel paths in virtual reality experiments for tunnel safety analysis

A case study on the analysis of evacuation travel paths in virtual reality (VR) tunnel fire experiments is presented to increase the understanding on evacuation behaviour. A novel method based on the study of the parametric equations of the occupants’ evacuation travel paths using vector operators inspired by functional analysis theory and the new concept of interaction areas (IAs) is introduced. IAs are presented and calculated in order to represent the distance of an occupant from a reference point (e.g., an emergency exit, the fire source, etc.) over time. The method allows comparisons of travel paths between experimental groups as well as comparisons with reference paths (e.g. user-defined paths, real-world paths, etc.). Results show that a common assumption employed by evacuation models (the use of a hypothetical path based on the shortest distance) may be an over-simplistic approximation of the evacuation paths.     

二维网格中基于最小通路区的自适应和最小容错路由算法

网格结构是并行与分布式处理中最流行的一种网络拓扑结构。在存在故障的情况下，如何设计具有最优性的容错路由算法一直是研究的热，点问题。本文研究了采用故障块模型的二维网格的最小路由问题，提出存在最小通路的一个充分必要条件。基于最小通路区（RMP）的概念，提出一种自适应的最小容错路由算法。如果源节点和目的节点之间存在最小通路区，则在最小通路区中进行自适应最小容错路由；反之，则采用多阶段最小容错路由。主要思想就是在存在故障的情况下，尽量保证路由算法能走最短路径。因为只要求知道每个节点的局部信息，故算法是分布式的。     

Vertex covering by paths on trees with its applications in machine translation

Given a tree and a set of paths in the tree, the problem of finding a minimum number of paths from the given path set to cover all the vertices in the tree is investigated in the paper. To distinguish from the classical path cover problem, such an optimization problem is referred to as vertex covering by paths. The problem and its edge variant, edge covering by paths, find applications in machine translation. Complexity and algorithmic results are presented for the problem and its edge variant.     

Improved algorithm for finding next-to-shortest paths

We study the problem of finding the next-to-shortest paths in a weighted undirected graph. A next-to-shortest (u,v)-path is a shortest (u,v)-path amongst (u,v)-paths with length strictly greater than the length of the shortest (u,v)-path. The first polynomial algorithm for this problem was presented in [I. Krasikov, S.D. Noble, Finding next-to-shortest paths in a graph, Inform. Process. Lett. 92 (2004) 117-119]. We improve the upper bound from O(n³m) to O(n³).     

基于Web使用挖掘技术的个性化教育网站构筑

本文介绍了个性化网络教育的特点，对在Web服务器端和客户端进行学生浏览路径模式采集的各种方法进行了分析，探讨了如何将Web使用挖掘技术应用到个性化网络教育，最后介绍了由我们开发的个性化教育网站。     

Time-minimal paths amidst moving obstacles in three dimensions

A path-planning problem is considered in the presence of moving polygonal obstacles in three dimensions. A particle is to be moved from a given initial position to a destination position amidst polygonal disjoint barriers moving along known linear trajectories. The particle can move in any direction in space with a single constraint that it cannot move faster than a given speed bound. All obstacles are slowly moving, i.e., their speeds are strictly slower than the maximum speed of the particle. The destination point is also permitted to move along a known trajectory and is assumed to be collision-free at all times. Three properties are stated and proved for a time-minimal path amidst moving polygonal barriers. A few extensions are considered, including piecewise linear motions of the obstacles.     

计算机绘制网络图所有路径计算方法的研究

本文研究了影响网络图线路数量的因素,提出了节点和有向线是组成线路的基本要素,以及用计算机绘制和计算网络的所有路径的计算方法.此方法可解决任意节点和有向线的网络中所有线路值和关键路径的时间计算.     

组合逻辑电路的逆向分析和条件通路法

本文指出目前组合逻辑电路分析方法的不足,提出了一种新的方法——条件通路法,使组合电路的逆向分析得以容易实现,从而完善了组合逻辑电路的分析方法。     

Simple On-Line Algorithms for the Maximum Disjoint Paths Problem

In this paper we study the classical problem of finding disjoint paths in graphs. This problem has been studied by a number of authors both for specific graphs and general classes of graphs. Whereas for specific graphs many (almost) matching upper and lower bounds are known for the competitiveness of on-line algorithms, not much is known about how well on-line algorithms can perform in the general setting. The best results obtained so far use the expansion of a network to measure the algorithms performance. We use a different parameter called the routing number that, as we will show, allows more precise results than the expansion. It enables us to prove tight upper and lower bounds for deterministic on-line algorithms. The upper bound is obtained by surprisingly simple greedy-like algorithms. Interestingly, our upper bound on the competitive ratio is even better than the best previous approximation ratio for off-line algorithms. Furthermore, we introduce a refined variant of the routing number and show that this variant allows us, for some classes of graphs, to construct on-line algorithms with a competitive ratio significantly below the best possible upper bound that could be obtained using the routing number or the expansion of a network only. We also show that our on-line algorithms can be transformed into efficient algorithms for the more general unsplittable flow problem.