Graph‐based optimal asynchronous scheduling in large propagation delay underwater acoustic sensor networks

Optimal scheduling is essential to minimize the time wastage and maximize throughput in high propagation delay networks such as in underwater and satellite communication. Understanding the drawbacks of synchronous scheduling, this paper addresses an asynchronous optimal scheduling problem to minimize the time wastage during the transmission. The proposed scheduling problem is analyzed in both broadcast and non‐broadcast networks, which is highly applicable in high propagation delay networks. In broadcast networks, the proposed scheduling method reduces to a graph‐theoretic model that is shown to be equivalent to the classic algorithmic asymmetric traveling salesman problem (TSP) which is NP‐Hard. Although it is NP‐Hard, the TSP is well‐investigated with many available methods to find the best solution for up to tens of thousands of nodes. In non‐broadcast networks, the optimal solution to the scheduling problem considers the possibility of parallel transmission, which is optimized using graph coloring algorithm. The groups obtained through graph coloring are solved using Asymmetric Traveling Salesman algorithm to obtain the optimal schedule. The proposed method efficiently solves the scheduling problem for networks of practical size.     

一种融合节点先验信息的图表示学习方法

图表示学习是实现各类图挖掘任务的基础。现实当中的图数据,不仅包含复杂的网络结构,还包括多样化的节点信息。如何将网络结构和节点信息更加有效地融入图的表示学习中,是一个重要的问题。为了解决这一问题,本文基于深度学习提出了融合节点先验信息的图表示学习方法。该方法将节点特征作为先验知识,要求学习到的表示向量同时保持图数据中的网络结构相似性和节点特征相似性。该方法的时间复杂度为O（|V|）,其中|V|为图节点数量,表明该方法适用于大规模图数据分析。同时,在多个数据集上的实验结果表明,所提出的方法相比目前流行的几种基线方法,在分类任务上能够获得良好而稳定的优势。     

基于形状参数的车型快速分类方法研究

车型分类识别是智能交通系统的重要组成部分,针对视频图像中道路行驶车辆进行研究,设计了一种基于机器视觉的车型分类系统.首先利用迭代均值背景差分和三侦间时间差分相融合的运动目标检测法得到目标区域,通过链码计算出汽车的拐点、矩形度、离地间隙等形状参数,通过二叉树结构支持向量机对六种车型进行分类,并用交叉验证法自动选择最佳分类参数提高分类器的性能.仿真结果表明,该方法检测准确率高,要求训练样本少,能显著提高数据挖掘的效率.     

引入外部词向量的文本信息网络表示学习

针对信息网络（text-based information network）现有研究多基于网络自身信息建模,受限于任务语料规模,只使用任务相关文本进行建模容易产生语义漂移或语义残缺的问题,本文将外部语料引入建模过程中,利用外部语料得到的词向量对建模过程进行优化,提出基于外部词向量的网络表示模型NE-EWV（network embedding based on external word vectors）,从语义特征空间以及结构特征空间两个角度学习特征融合的网络表示。通过实验,在现实网络数据集中对模型有效性进行了验证。实验结果表明,在链接预测任务中的AUC指标,相比只考虑结构特征的模型提升7%~19%,相比考虑结构与文本特征的模型在大部分情况下有1%~12%提升;在节点分类任务中,与基线方法中性能最好的CANE性能相当。证明引入外部词向量作为外部知识能够有效提升网络表示能力。     

Robust output‐feedback control of state‐multiplicative noisy discrete‐time systems

Linear discrete‐time systems with stochastic and deterministic polytopic type uncertainties in their state‐space model are considered. A dynamic output‐feedback controller is obtained via a new approach that allows a derivation of a controller in spite of parameter uncertainty. In the proposed approach, the system is described via a difference equation and an augmented system is then used to obtain the output‐feedback controller parameters. The controller is obtained without assuming a specific structure to the quadratic Lyapunov function, and it is the first time that an output‐feedback controller is obtained for robust state‐multiplicative systems. The controller minimizes the stochastic L₂‐gain of the closed‐loop where a cost function is defined to be the expected value of the standard performance index with respect to the stochastic uncertainty. Two examples are given where the second of which demonstrates the applicability of our theory to a robot manipulator system. Copyright © 2016 John Wiley & Sons, Ltd.     

江水源热泵套管式换热器换热效率的实验研究和模拟分析

利用长江水源的江水源热泵系统是重庆市可再生资源利用的重要形式,其换热器的性能对系统能效具有显著的影响,论文研究了使用半圆环形折返管的套管式换热器的换热效率.实验证明折返管曲率的增加可以有效地提高换热器的换热效率,与直管套管式换热器相比,当R/r=5时,其换热效率可提高2.5%.为分析半圆环形折返管的换热机理,论文利用计算流体力学(CFD)进行了流动、温度场和换热模拟.为保证在旋转流和大曲率情况下计算的准确性,模拟分析采用了修正后的RNG k-ε湍流模型,模拟分析的结果表明:折返管内存在者明显的二次流漩涡,它对边界层的扰动是造成换热器换热效率随着折返管曲率增加而提高的主要原因.论文综合实验和模拟分析结果,同时考虑江水的泥沙问题和换热效率,给出了半圆环形折返换管的适宜曲率.     

基于四边形网格的新细分算法的研究

采用重复平均的方法对细分曲面进行平滑细分,提出一种基于四边形网格的新细分算法．该算法每细分一次四边形网格,其数目增加为原来的两倍,所以此细分算法具有网格几何操作简单,所得网格数据量增长相对缓慢的优点,应用广泛,更适合3D信号网络传输等应用领域,并且生成曲面在规则点具有C^2连续性,在非规则点具有C^1连续性．     

图Pu,v(n)的邻强边染色*

u,v两点间连接n条内部不相交的路,其中最多有一条长度为1,记做Pu,v(n)。给出一个算法,利用计算机寻找边染色的规律,进一步给出了Pu,v(n)的邻强边染色法,从而确定了Pu,v(n)的邻强边染色数。进一步讨论了至多含有两个顶点度大于2的部分简单连通图的邻强边色数。     

On the parameterized vertex cover problem for graphs with perfect matching

A vertex cover of an n-vertex graph with perfect matching contains at least n/2 vertices.In this paper,we study the parameterized complexity of the problem vc-pm*that decides if a given graph with perfect matching has a vertex cover of size bounded by n/2+k.We first present an algorithm of running time O*(4k)for a variation of the vertex cover problem on K¨onig graphs with perfect matching.This algorithm combined with the iterative compression technique leads to an algorithm of running time O*(9k)for the problem vc-pm*.Our result improves the previous best algorithm of running time O*(15k)for the vc-pm*problem,which reduces the problem to the almost 2-sat problem and solves the latter by Razgon and O’Sullivan’s recent algorithm.     

点可区别全色数的一个上界

设G是简单图,f是从V（G）UE（G）到{1,2,…,k）的一个映射．对每个u∈y（G）,令c（u）={f（u）}v∈V（G）,uv∈ E（G）}．如果,是k-正常全染色,且对任意u,v∈V（G）（u≠v）,有c（u）≠c（v）,那么称f为图G的k-点可区别全染色（简记为k-VDTC）．数χvt（G）=min{k｜G-有k—VDTC}称为图G的点可区别全色数．通过应用概率方法,证明了对任意最大度A≥2的图G,χvt（G）≤32（△＋1）．