structuring and manipulating hand-drawn concept maps

Concept maps are an important tool to knowledge organization,representation, and sharing. Most current concept map tools do not provide full support for hand-drawn concept map creation and manipulation, largely due to the lack of methods to recognize hand-drawn concept maps. This paper proposes a structure recognition method. Our algorithm can extract node blocks and link blocks of a hand-drawn concept map by combining dynamic programming and graph partitioning and then build a concept-map structure by relating extracted nodes and links. We also introduce structure-based intelligent manipulation technique of hand-drawn concept maps. Evaluation shows that our method has high structure recognition accuracy in real time, and the intelligent manipulation technique is efficient and effective.

Structures of an asymmetrically coupled double-well superlattice by double-crystal X-ray diffraction

An asymmetrically coupled (GaAs/AlAs/GaAs/AlAs)/GaAs (001) double-well supperlattice is studied by HRDCD (high resolution double-crystal X-ray diffractometry). The intensity of satellite peaks is modulated by wave packet of different sublayers. In the course of simulation, the satellite peaks in the vicinity of the node points of wave packet are very informative for precise determination of sublayer thickness and for improving accuracy.

Study of double barrier superlattice by synchrotron radiation and double-crystal x-ray diffraction

An (A1As/GaAs/A1As/A1GaAs)/GaAs(001) double-barrier superlattice grown by molecular beam epitaxy (MBE) is studied by combining synchrotron radiation and double-crystal x-ray diffraction (DCD). The intensity of satellite peaks is modulated by the wave function of each sublayer in one superlattice period. Simulated by the x-ray dynamical diffraction theory, it is discovered that the intensity of the satellite peaks situated near the modulating wave node point of each sublayer is very sensitive to the variation of the layer structural parameters, The accurate layer thickness of each sublayer is obtained with an error less than 1 Angstrom. Furthermore, x-ray kinematical diffraction theory is used to explain the modulation phenomenon. (C) 1996 American Institute of Physics.

Seed germination and seedling morphology of the seagrass, Halophila engelmannii (Hydrocharitaceae)

Seeds of Halophila engelmannii Aschers., that were collected in Redfish Bay, Texas, at weekly intervals from mid-May to mid-June 1986, began to germinate 3–4 weeks after collection. Most of the collections subsequently showed an increase in the rate of germination under increased light intensity and all had a stoppage of germination after transfer to darkness, indicating a light requirement to break endogenous seed dormancy. During the 5 weeks after seeds germinated, seedlings in soil culture produced a rosette of six leaves before the appearance of a rhizome bud in the axil of the third leaf. The first node of the rhizome produced a root and an upright shoot with a pseudowhorl of three to five leaves.

3D metal-organic frameworks incorporating water-soluble tetra-p-sulfonatocalix[4]arene

Water-soluble tetra-p-sulfonatocalix[4]arene, acting as a four-connected node, bridges the rare earth cations into a 3D porous MOF in which 1D smaller circular hydrophilic channels and larger quadratic ones are lined up along the c axis and interconnected to each other by the calixarene cavities and other interstices.

Study on computer perception of topological symmetry

A new algorithm for computer perception of topological symmetry is proposed. A node library containing various kinds of nodes is built, and the index number of the library is used as initial atom class identifier (CI) to discriminate the different types of non-hydrogen atoms. The path index (PI) and ringindex (RI) are calculated from the CI, and the global topological enviroment is defined as the sum of PIs and RIs. The topological symmetry can be detected by the iterative calculation of the global topological enviroment.

A new topological index for the Changchun institute of applied chemistry C-13 NMR information system

A method to assign a single number representation for each atom (node) in a molecular graph, Atomic IDentification (AID) number, is proposed based on the counts of weighted paths terminated on that atom. Then, a new topological index, Molecular IDentification (MID) number is developed from AID. The MID is tested systematically, over half a million of structures are examined, and MID shows high discrimination for various structural isomers. Thus it can be used for documentation in the Changchun Institute of Chemistry C-13 NMR information system.

A NEW SCHEME FOR ASSIGNMENT OF A CANONICAL CONNECTION TABLE

A new algorithm for deriving canonical numbering of atoms in a molecular graph has been developed. Some graph invariants, such as node properties, degree (connectivity), topological path, the smallest node ring index, etc., are encoded together to partit

移动机器人路径规划方法研究

针对室内动态非结构化环境下的移动机器人路径规划问题,提出了一种能够将全局路径规划方法和局部路径规划方法相结合、将基于反应的行为规划和基于慎思的行为规划相结合的路径规划方法.全局路径规划器采用A*算法生成到达目标点的子目标节点序列;局部路径规划器采用改进的人工势场方法对子目标节点序列中相邻两节点进行路径平滑和优化处理.在考虑了移动机器人运动学约束的前提下,该方法不但能够充分利用已知环境信息生成全局最优路径,而且还能及时处理所遇到的随机障碍信息.仿真研究与在室内复杂环境下的实际运行结果验证了该方法的有效性.

一种高效覆盖的水下传感器网络部署策略

传感器节点的部署直接关系到水下传感器网络的成本和性能。考虑到传感器节点间具有很强的协同能力,该文提出一种基于检测融合的部署策略。采用Neyman-Pearson准则融合单元网格内所有传感器节点的检测信息,实现正方形和正三角形两种单元网格的高效覆盖,进而分别给出针对两种单元网格的监测区域网格划分方法,从而确定监测区域需要的传感器节点数量以及放置的具体位置。通过仿真实验验证了该部署策略的有效性。结果表明,与不采用检测融合时相比,降低了传感器节点冗余度。使用相同数量的传感器节点,新的部署策略能够在保证一定感知质量的基础之上获得更大的覆盖范围。

面向数据收集的无线传感器网络节点部署问题研究

随着MEMS、无线通信、自动控制和人工智能等技术的快速发展，无线传感器网络引起了学术界的极大关注。它的出现改变了人与自然界的交互方式，其应用领域将会深入到社会生活的各个方面。 节点部署问题是无线传感器网络研究的基本问题之一。在无线传感器网络的某些实际应用中，节点部署通常采用人工部署方式，为满足网络的节能性、可靠性、实时性等性能需求，需要额外部署一些节点。为限制网络布设成本，要对这些新增加的节点进行有针对性地部署。基于这种应用环境，论文对面向数据收集的无线传感器网络节点部署问题展开研究工作，主要的研究内容与成果包括以下几个方面。 论述了无线传感器网络节点部署问题的研究内容、分类和评价体系，系统地总结了前人的研究成果和不足。 为改善网络的连通性和满足网络生命期需求，提出了一种启发式的两阶段中继节点部署策略。第一阶段的部署确保了网络连通性；第二阶段部署，结合负载平衡的路由协议，满足了网络的生命期需求。仿真结果表明该方法在满足上述性能需求的前提下，最大限度地减少了需要部署的中继节点数目。 针对网络中簇首选择不合理导致数据收集成本过高的问题，提出了面向数据收集成本最优化的簇首节点选择算法。当网络状态一定时，簇首节点的优化选择问题是一类组合优化问题。论文首先提出了基于小规模网络的全局最优化的簇首节点选择算法（BFM）。针对BFM算法复杂度高的缺点，进而提出了基于大规模网络的启发式的簇首节点选择算法，该算法可以在较短时间内得到问题的次优解。 考虑网络簇首的容量限制和最大簇半径限制，把簇首节点的优化部署问题形式化为整数规划问题。提出两种启发式的簇首优化部署策略：基于K-平均的簇首部署策略和基于K-平均与模拟退火混合算法的簇首部署策略。前者适用于网络运行时的动态部署，后者适用于网络投入使用前的规划部署。仿真结果表明，分簇后的网络在满足上述限制的情况下，最大限度地延长了网络生命期。 有针对性的节点部署离不开网络状态监测，为使网络状态监测不过多占用网络资源，提出了一种高效的网络状态监测机制。通过对节点编码并在节点间建立起一个逻辑层次簇结构，利用各个子簇状态数据的相似性和编码的连续性，实现了网内无损聚合。该监测机制使得网络状态信息的收集，在不丢失数据细节信息的情况下，数据通信量大大减少。 本论文的研究仅为无线传感器网络中的规划部署问题提供了一个框架，尚未形成一个完整可行的网络规划部署系统。各项研究成果可以为无线传感器网络设计者、方案提供者以及无线传感器网络应用的系统集成，提供一些有益的指导。

移动机器人几何-拓扑混合地图的构建及自定位研究

基于墙角、房门和通路等高级环境特征的辨识与提取,依据几何和拓扑环境模型完成混合地图的构建,并根据混合地图的特点,提出在局部几何环境采用扩展卡尔曼滤波算法实现移动机器人的位姿跟踪,而在拓扑地图的节点位置则根据绑定的高级环境特征进行位姿再校正的混合定位方法.将该方法应用于实际移动机器人平台,所得结果证明了方法的有效性和实用性.

基于启发式节点增强策略的PRM路径规划方法

针对一般的PRM方法用于移动机器人对复杂地形路径搜索存在的缺陷 ,本文对PRM方法进行了改进 ,提出了一套基于启发式的节点增强的策略 ,提高了PRM方法节点增强阶段对环境的适应性 .此外 ,本文建立了相应的仿真实验系统对策略的有效性进行了实验与分析