共查询到20条相似文献，搜索用时 15 毫秒
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This paper deals with the problem of finding graphs (directed and undirected) maximizing the number of spanning trees among the regular graphs with the same number of nodes and edges. The approach is based on heuristic algorithms such as k-optimal and evolutionary. The emphasis is rather on checking whether these techniques are applicable to solving extremal graph problems than investigating generic structures of optimal graphs. For this reason circulant graphs, for which computationally effective tree counting formulas exist, are discussed first and then the results extended to cover the class of regular graphs. 相似文献
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Mont Hubbard 《Journal of The Franklin Institute》1979,308(4):405-421
Bond graphs are used to generate the equations of motion of a whirling flywheel. The formulation is shown to be a natural one when control forces and moments are included for active control of the whirling modes. Critical frequencies are interpreted as rotational speeds at which non-zero equilibrium configurations exist for displacements (as opposed to the more familiar momenta) and arise when the system dynamics matrix of the complete whirl motion has two zero eigenvalues. In addition, oscillatory modes corresponding to non-zero eigenvalues are examined. Time simulations and other numerical results are given for an example flywheel system which has been proposed for electric utility energy storage. 相似文献
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Tadao Murata 《Journal of The Franklin Institute》1980,310(1):41-50
This paper is concerned with the applicability of network theory to those aspects of distributed/parallel processing that can be modeled by marked graphs. First, several examples are given to illustrate that a wide variety of computation schemes can be modeled by marked graphs. Subsequently, the following topics are discussed: application of KVL to fault detection and isolation, KCL and Tellegen's Theorem applied to marked graphs, and the relationship between the maximum (minimum) storage requirement and the minimum (maximum) power. 相似文献
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Samuel D. Bedrosian 《Journal of The Franklin Institute》1981,312(6):417-430
The properties of special pairs of tree counting polynomials that relate to a class of incomplete graphs and their complements are presented. These polynomial pairs are related by the previously defined binary complementing operation.In contrast with alternative graph representations, they offer the possibility of serving as a convenient signature for the specific configurations.In Part II, a new constructive procedure is presented for deriving these polynomials. It is shown that the new algorithmic approach facilities obtaining the polynomials for cases not readily obtained by use of generic factors of the basic subgraphs. 相似文献
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This paper investigates the issue of finite/fixed-time bipartite consensus (FFTBC) of multi-agent systems with signed graphs. A new unified framework of finite-time and fixed-time bipartite consensus is built via some discontinuous control protocols based on the theory of differential inclusion and set-valued Lie derivative. Under the structurally balanced or unbalanced signed graphs, the goal of FFTBC is reached by a common discontinuous controller with different control gains, which fills the gap in studying FFTBC issues with discontinuous protocols. Some numerical examples with comparisons are given to demonstrate the effectiveness of our designs. 相似文献
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The induced matching partition number of graph G is the minimum integer k such that there exists a k-partition (V1,V2,…Vk) of V(G) such that,for each i(1≤i≤k),G[Vi]is 1-regular.In this paper,we study the induced matching partition number of product graphs. We provide a lower bound and an upper bound for the induced matching partition number of product graphs, and exact results are given for some special product graphs. 相似文献
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A new calculation is given for the number of spanning trees in a family of labelled graphs considered by Kleitman and Golden, and for a more general class of such graphs. 相似文献
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《Journal of The Franklin Institute》2023,360(12):7808-7831
This paper solves the finite-time consensus problem for discrete time multi-agent systems (MASs) where agents update their values via linear iteration and the interactions between them are described by signed digraphs. A sufficient condition is presented that the agents can reach consensus on any given linear function of multiple initial signals in finite time, i.e., there exists an eventually positive Laplacian-based matrix associated with the underlying graph. We prove that the linear iterative framework “ratio consensus” developed for unsigned graphs in the literature can be extended to the computation for signed graphs with appropriate modifications. Our method weakens the limitation of the iterative framework on the “marginal Schur stability” of the weight matrix without increasing the computational complexity. Reaching average consensus on unsigned graphs as in the literature is regarded as a special case of our algorithm. Two illustrative examples are presented to demonstrate the correctness of the proposed results. 相似文献
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Mfanafikile Don Mhlongo 《Journal of The Franklin Institute》2009,346(8):830-839
This paper looks at the sensitivity of thickness to variation of friction. The models of friction used are: the classic Amontons-Coulomb; a nonlinear pressure-dependent model proposed by Wriggers, vu Van and Stein; and a velocity-dependent model proposed by Molinari, Estrin and Mercier. They are coded in FORTRAN for use with finite element program ABAQUS. The contact problem is then formulated in the total Lagrangian formulation for contact between an elastic-plastic body and rigid tools. The variational (weak) form of the formulation is given and this is discretized by finite element method. To test and compare the models, one common metal forming processes is simulated: deep drawing of a square-cup. The sensitivity graphs showing each of the three friction models together is given at the end. One other conclusion although not major part of this work is that Amonton-Coulomb is not the best model suited for contact conditions in metal forming processes, because Wriggers et al. model and Molinari et al. model provide better results for modelling bends and corners. 相似文献
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In existing unsupervised methods, Latent Semantic Analysis (LSA) is used for sentence selection. However, the obtained results are less meaningful, because singular vectors are used as the bases for sentence selection from given documents, and singular vector components can have negative values. We propose a new unsupervised method using Non-negative Matrix Factorization (NMF) to select sentences for automatic generic document summarization. The proposed method uses non-negative constraints, which are more similar to the human cognition process. As a result, the method selects more meaningful sentences for generic document summarization than those selected using LSA. 相似文献
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《Information processing & management》2002,38(1):111-140
This research is a part of ongoing study to better understand citation analysis on the Web. It builds on Kleinberg's research (J. Kleinberg, R. Kumar, P. Raghavan, P. Rajagopalan, A. Tomkins, Invited survey at the International Conference on Combinatorics and Computing, 1999) that hyperlinks between web pages constitute a web graph structure and tries to classify different web graphs in the new coordinate space: out-degree, in-degree. The out-degree coordinate is defined as the number of outgoing web pages from a given web page. The in-degree coordinate is the number of web pages that point to a given web page. In this new coordinate space a metric is built to classify how close or far are different web graphs. Kleinberg's web algorithm (J. Kleinberg, Proceedings of the ACM-SIAM Symposium on Discrete Algorithms, 1998, pp. 668–677) on discovering “hub web pages” and “authorities web pages” is applied in this new coordinate space. Some very uncommon phenomenon has been discovered and new interesting results interpreted. This study does not look at enhancing web retrieval by adding context information. It only considers web hyperlinks as a source to analyze citations on the web. The author believes that understanding the underlying web page as a graph will help design better web algorithms, enhance retrieval and web performance, and recommends using graphs as a part of visual aid for search engine designers. 相似文献
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《Information processing & management》2020,57(2):102054
Social networks and many other graphs are attributed, meaning that their nodes are labelled with textual information such as personal data, expertise or interests. In attributed graphs, a common data analysis task is to find subgraphs whose nodes contain a given set of keywords. In many applications, the size of the subgraph should be limited (i.e., a subgraph with thousands of nodes is not desired). In this work, we introduce the problem of compact attributed group (AG) discovery. Given a set of query keywords and a desired solution size, the task is to find subgraphs with the desired number of nodes, such that the nodes are closely connected and each node contains as many query keywords as possible. We prove that finding an optimal solution is NP-hard and we propose approximation algorithms with a guaranteed ratio of two. Since the number of qualifying AGs may be large, we also show how to find approximate top-k AGs with polynomial delay. Finally, we experimentally verify the effectiveness and efficiency of our techniques on real-world graphs. 相似文献
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产业共性技术的界定及选择方法研究——基于科技计划管理的视角 总被引：2，自引：0，他引：2
产业共性技术的研发对于一国的产业进步和经济社会发展具有巨大的推动作用.科技计划是国家推动产业共性技术研发的重要载体,本研究以科技计划管理为视角,在系统分析国内外产业共性技术界定和选择方法的基础上,提出国家科技计划实施中产业共性技术的界定和选择方法体系.在国家科技计划实施中,产业共性技术可从技术范围、研发与应用的主体、综合效益三个方面进行界定;"自上而下"和"自下而上"相结合的选择方法体系可以用于国家层面上科技计划执行中产业共性技术的选择. 相似文献
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This paper investigates the determinants of economic growth from both a theoretical and an empirical perspective. The paper combines the supermultiplier model of growth with the Neo-Schumpeterian framework that emphasises the entrepreneurial role of the state. We aim to detect the macroeconomic effect generated by alternative fiscal policies: generic ones and more directed ‘mission-oriented’ ones. Using an SVAR model for the US economy for the 1947–2018 period, we show that mission-oriented policies produce a larger positive effect on GDP (fiscal multiplier) and on private investment in R&D (crowd-in effect) than the one generated by more generic public expenditures. 相似文献
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首先根据共性技术的特点,初步设计了共性技术选择的25个影响因素,并利用问卷调查结果进一步筛选出共性技术选择的18个主要影响因素;再利用主成分分析法确定主要影响因素的重要性程度系数,给出了共性技术选择的打分公式;最后运用改进的德尔菲方法邀请相关领域专家对候选共性技术进行打分,依据得分大小,可为政府购买的共性技术决策提供依据,并选择出政府拟开发的共性技术。并已给出了一个决策案例。 相似文献
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This paper investigates average consensus problem in networks of continuous-time agents with delayed information and jointly-connected topologies. A lemma is derived by extending the Barbalat's Lemma to piecewise continuous functions, which provides a new analysis approach for switched systems. Then based on this lemma, a sufficient condition in terms of linear matrix inequalities (LMIs) is given for average consensus of the system by employing a Lyapunov approach, where the communication structures vary over time and the corresponding graphs may not be connected. Finally, simulation results are provided to demonstrate the effectiveness of our theoretical results. 相似文献
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In this article, we use the implementation of an expert system to improve blast furnace control in the French steel industry to illustrate the problem of knowledge articulation/codification. Blast furnace related knowledge still largely takes the form of empirical know-how in general and expert know-how tied to specific individuals in particular. Therefore, the articulation/codification of knowledge in this field is a difficult task requiring the identification and selection of ‘best practices’ for the purpose of codification. This process, in turn, affects daily routines and creates new forms of generic knowledge that make use of local knowledge. These new forms of generic information reinforce the tendency to appropriate private knowledge currently prevailing in Usinor, a large French steel company, and create new routes and new insights for R&D policy. 相似文献
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【目的/意义】网络舆情是群体智慧的涌现形式之一,探究不同平台的网络舆情信息所蕴含的群体智慧,对
网络舆情的管理与引导具有重要的理论价值与现实意义。【方法/过程】研究以新浪微博和抖音短视频为数据源,基
于ELECTRA和REDP方法分别对舆情文本信息进行实体抽取与关系抽取,分别构建微博平台与短视频平台的网
络舆情知识图谱,并对各网络舆情知识图谱进行对比分析。【结果/结论】研究结果表明,微博与短视频平台的舆情
信息通常会涉及相同的主流内容,同时各平台也存在不同的衍生内容。在信息内容方面,新浪微博平台的舆情信
息的内涵更加丰富、外延更加广泛。在知识的贡献与获取方面,新浪微博平台的用户更加偏向于参与舆情话题的
讨论,主动贡献知识。在知识图谱构建方面,短视频平台舆情内容中的知识实体同时出现的联合概率较高,更容易
形成知识三元组,舆情知识也更加聚焦。【创新/局限】本研究分别构建了新浪微博与抖音短视频平台的舆情知识图
谱,并对各平台知识图谱进行对比分析。在未来的研究中,研究将对各平台知识图谱差异性的产生过程与原因进
行更加深入地思考。 相似文献