三次图上的一类Cayley图

沿用习惯的说法将三次图表示为一个简单的连通的正则度为3的图,本文研究了三次图上的一次Cayley图。     

单自由度平面闭链机构构型方法的研究

提出了一种关于自由度平面闭链机构的构型方法,即\"平面图形构造方法\"。利用这种方法进行机构结构综合的主要过程是：先根据机械功能确定运动链的组成成分;再按这些成分构造平面图;最后在平面图上进行机构的构型和变异,并将其中结构最优者转换为机构简图。     

关于一些特殊图上的强罗马控制数的研究

图的控制数的计算是NP-完备问题,因此探索图的控制数的精确值或较好的上下界具有较大的理论意义.强罗马控制数是一类重要的控制数,不仅在蛋白质结构的研究、电路图设计、计算机编程等方面有着广泛的应用,而且在逻辑学、语言学、通讯网络、人工智能等科学领域的应用也尤为突出.本文主要应用数学归纳法和分类讨论法,深入讨论了图的强罗马控...     

Two new heuristic algorithms for the maximal planar layout problem

The adjacency problem is an important subproblem in facility layout planning. It is known to be NP-complete, so heuristics are required to solve large problem instances. In this paper two new heuristics for the adjacency problem are introduced which belong to a special class of constructive methods called Triangulation Expansion Heuristics. Extensive numerical experiments have been carried out in order to evaluate the proposed methods in terms of computing times and solution quality. It has been found that at least one method is clearly superior to the best methods proposed in the literature so far (Eades et al. 1982, Leung 1992).     

路图与线图的一个综述

线图的概念最早是由Whitney提出的,在所有图的变换中,线图可能是研究最广泛的一种变换了。关于线图的研究已经有很多结果,路图变换是线图的一种自然推广。在这篇综述中,我们可以看到有时路图与线图的性质差异很大,有些问题对路图而言变得相当复杂和困难。这篇文章主要通过以下几个方面比较和总结了路图与线图的一些结果:基本事实,判定问题,刻画问题,贯穿性,连通度。     

一类新的互连网络:三角塔网络

本文提出并分析了一种新的互连网络—三角塔网络.当n4或n=4时,它是极大连通的,紧超连通的,即三角塔网络的连通度κ(TTn)是2n-3.星网络是三角塔网络的子网络,故而三角塔网络除了继承星网络的很多优良性质(例如:点对称性、连通性、点可迁性等),还说明Sn能以膨胀数1嵌入TTn.当三角塔网络和超立方体与冒泡排序网络有近乎相同的顶点数时,三角塔网络的直径和连通度与超立方体与冒泡排序网络的直径和连通度相比直径更小、连通度更大.本文给出了三角塔网络的直径和平均距离,并提出了关于三角塔网络Hamilton性的一簇猜想,并且证明这个猜想对于n=3,4以及n=5,6,k=1,2时是正确的.     

一种新型雷达天线折叠机构研究与实现

为实现大尺寸平面阵列天线雷达的海陆空多种运输方式兼容,特别是铁路运输时直接驶上平板车,采用了一种新型的前翻四连杆折叠机构。着重介绍了该机构中以液压油缸作为驱动源的四连杆折叠机构的工作原理和结构设计,分析了折叠机构运动规律和受力情况,并在折叠机构系统设计中采用驱动源同步来实现两套折叠机构在展开与折叠过程中实时同步。该机构成功用于某高机动雷达的大型平面阵列天线折叠,通过长期使用证明机构性能良好、可靠性高。     

双活塞式压力计准确度等级的确定

双活塞式压力计基于不同结构可分为双活塞式压力真空计和双量程活塞式压力计两种。针对后者的结构特点,分析两套活塞系统共用一套砝码的问题,根据活塞的参数以及专用砝码质量计算出标称值下的实际压力值。本研究根据不同压力量程段来划分活塞式压力计的准确度等级,实现活塞式压力计的溯源性校准,以保证压力量传中的准确性和一致性。     

用边界元反分析构造平面残余应力场

基于固有应变概念,采用边界元方法,提出一种反方法构造连续的满足域内自平衡条件的平面残余应力场。考虑到反分析的稳定性,固有应变场用一系列光滑基函数(如多项式和三角函数)近似;为了识别由剪切固有应变引起的残余应力,求出对应于固有应变的位移特解与面力特解,将域内积分用双重互易边界元法转换为边界积分,保持了边界元法的优势;同时导出了灵敏度矩阵的显式表达,以提高反分析的效率。最后给出了两个算例验证方法的可行性。     

图学在人类文明进展中的作用研究

世界5大文明中心古老的文字都起源于图,图在人类文明进展中起很大作用并占重要地位.论述了古汉语象形文字、古埃及象形文字、古印度印章象形文字、中美洲玛雅象形文字、苏美尔楔形文字等世界文明中心文字的起源与图的关系.认为图学在人类文明进展中的核心作用是由“灵魂、主体、精髓、基础”构成的.物质形态与宇宙同生并存,图学具有叙述苍穹变化规律、承载人类文明信息、展示人类创新文明的重要功能.图学发展伴随着人类文明的过去、现在和未来,当代图学要真正承担起认识世界、传承文明、创新理论、咨政育人、服务社会、创新文化的神圣职责.     

基于QR码和DWT-SVD分解的双水印算法

目的为了进一步提高水印的鲁棒性和保护性,文中提出一种基于QR码和DWT-SVD分解的双重水印方案。方法将次级水印的奇异值嵌入主水印经一级离散小波变换后低频系数的奇异值中,再将含有次级水印信息的主水印奇异值嵌入主图像的二级小波变换后低频系数的奇异值中。结果经仿真实验发现,文中算法的主水印和次级水印PSNR值可达66 dB和60 dB,并对于高斯噪声、JPEG压缩、JPEG2000压缩、旋转攻击、对比度增强以及缩放攻击有一定的鲁棒性,攻击后提取的水印相关系数接近于1。结论算法属于非盲水印,在多种攻击情况下都能检测到次要水印,但有时候主水印会严重失真。     

Beyond its cost, the value of maintenance: An analytical framework for capturing its net present value

Maintenance planning and activities have grown dramatically in importance across many industries and are increasingly recognized as drivers of competitiveness if managed appropriately. Correlated with this observation is the proliferation of maintenance optimization techniques in the technical literature. But while all these models deal with the cost of maintenance (as an objective function or a constraint), only a handful addresses the notion of value of maintenance, and seldom in an analytical or quantitative way.In this paper, we propose that maintenance has intrinsic value and argue that existing cost-centric models ignore an important dimension of maintenance, namely its value, and in so doing, they can lead to sub-optimal maintenance strategies. We develop a framework for capturing and quantifying the value of maintenance activities. Our framework is based on four key components. First, we consider systems that deteriorate stochastically and exhibit multi-state failures, and model their state evolution using Markov chains and directed graphs. Second, we consider that the system provides a flow of service per unit time. This flow in turn is “priced” and a discounted cash flow is calculated resulting in a present value (PV) for each branch of the graph—or “value trajectory” of the system. Third as the system ages or deteriorates, it migrates towards lower PV branches of the graph, or lower value trajectories. Fourth, we conceptualize maintenance as an operator (in a mathematical sense) that raises the system to a higher PV branch in the graph. We refer to the value of maintenance as the incremental PV between the pre- and post-maintenance branches of the graphs minus the cost of maintenance. The framework presented here offers rich possibilities for future work in benchmarking existing maintenance strategies based on their value implications, and in deriving new maintenance strategies that are “value-optimized.”     

Location and layout planning

This paper gives a review on quantitative methods for microeconomic location planning which can be subdivided into facility location and layout planning. Depending on different objectives and restrictions, there is a large variety of problems, especially in the field of facility location planning. Basic models arising in discrete and continuous facility location planning (e.g., warehouse location, center, location routing, competitive location problems), as well as corresponding solution methods, are presented. Generalized models and recent developments in these fields are outlined. Within layout planning, the quadratic assignment problem and graph-theoretic concepts are considered.     

美国商业广告设计中的文化价值观

目的探究美国商业广告设计中的文化价值观,对美国是如何在现代广告创作中突出本土文化理念进行探讨。方法从消费心理的设计、形象表达的塑造、理想两极性的表现3个方面,以文化研究的视角来探析美国商业广告设计中的文化价值观及其表现特征,并进一步追溯这种价值观在美国所产生的根源,以及它对现代广告设计的影响。结论无论从风格上还是形式上,美国商业广告设计中的文化价值观,都映射着美国的时代变迁、民族心理及社会生活,它不仅对世界广告设计的研究起着重要的作用,而且对发掘各类现代艺术中潜在的文化内涵,也有着极为深刻的意义。