Papers by Keyword: Digraph

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Authors: Zi Han Hao, Hai Bao
Abstract: Traditional power flow calculation can only supply the information of the conventional electric parameters, such as node voltage, branch current, power, etc. The transmission of power which is injected into the network by each power source, including power supply paths, power belongs, relationship among the power injected into each nodes, cannot be given. To solve this problem, this paper using the theory of the physical distribution of power network’s energy, proposes a matrix method for describing the power transmission, expresses the value and supply paths of the power from each single source in power network with the analytic method.
Authors: De Zhen Zhang, Wei Shi Zhang, Jian Ming Zhang
Abstract: A new approach to conceptual design based on path decomposition of digraph is presented in the paper. The set of basic mechanisms is firstly defined and every single mechanism is taken as a basic element in the set. The relationships among basic elements are described with paths or loops in the graph theory. Therefore, the conceptual design can be visualized as searching a suitable loop in the set of basic mechanisms. The digraph and the path decomposition in the graph theory are applied to represent solutions of conceptual design, such as the sequence, existence and the concatenation formation and repetition. And then, an illation formula is derived and a construction tree of conceptual design process is provided. The generated schemes are further filtered using character restriction operation which followed corresponding rules, so as to identify feasible solutions. Finally, a design example is given to demonstrate the effectiveness of the proposed approach.
Authors: Qiang Wu, Ding We Wu, Qin Wang, Shao Min Wen, Rong Tu
Abstract: In this paper, a novel algorithm for mining maximal frequent itemsets is presented, which has a pre-processing phase where a digraph is constructed. The digraph represents the frequent 2-itemsets which play an important role on the performance of data mining. Then the search for maximal frequent itemsets is done in the digraph. Experiments show that the proposed algorithm is efficient for all types of data.
Authors: Yuan Hao Zhang, Jun Ren, Guang Na Yin
Abstract: Now the identification of knowledge units and the relationship among them is still subjective and lacks systematic and scientific method. For improving rationality, the article applies digraph theory and arithmetic. The article puts forward to aggregation knowledge node into knowledge unit on certain arithmetic, and confirms the relationship among knowledge units in an organization. Case study shows that this method is more effective and rational than traditional simple method.
Authors: Ai Bing Yu, L.J. Zhong, Xin Li Tian, F. Zou
Abstract: A new method is proposed for machinability evaluation of machinable ceramic materials. The relation of machinability attributes is modeled as a digraph, and machinability attribute matrix is defined. Machinability indexes are calculated with permanent function of the matrix, and machinabilities of machinable ceramics are ranked. Five composites consisting of CePO4 and zirconia were fabricated, measured and drilled with tungsten-cobalt carbide bits. Mechanical property parameters of Ce-ZrO2/CePO4 composites, including Vickers hardness, fracture toughness and Elastic modulus, are selected as machinability attributes. The experimental results of material removal rates are consistent with the ranking of machinability index values of Ce-ZrO2/CePO4 ceramics. The machinabilities of Ce-ZrO2/CePO4 ceramics improve with the increase of CePO4 proportions. Machinability of machinable ceramics can be evaluated with digraph method.
Authors: L.J. Zhong, Ai Bing Yu, S.Y. Yu, Hai Yan Du
Abstract: A new method is proposed for machinability comprehensive evaluation of engineering ceramic materials based on digraph theory. Machinability attributes of the materials are taken as the nodes and the correlations between attributes are taken as the edges. The digraph model for machinability evaluation of ceramics is set up. According to the diagraph model, the machinability attribute matrix was constituted. Then machinability indexes of ceramic materials were calculated with permanent function and machinabilities of the ceramics were evaluated. In this paper, mechanical property parameters of ceramic materials, including hardness, fracture toughness and elastic modulus, were selected as machinability attributes. Machinability of four typical engineering ceramics were evaluated and ranked with machinability indexes. The grinding experiments give further proof of evaluation results.
Authors: A.C. Igboanugo
Abstract: Concerned that management of job-oriented accidents has remained a daunting challenge for all stakeholders in Nigeria oil-industry, a longitudinal study was made to appraise the patterning of episodic incidence of industrial accidents in a typical oil and gas company operating in the Nigeria flank of the oil-rich Niger Delta Basin. A 10-year historical accident data were characterized and found to have absorbing chain properties. Four open-and-shot transition states namely : fatality, accident, near-miss and unsafe act, that are subject to ergodicity, were identified and used to craft a value digraph which define the stable transition probability matrix. The results, which suggest that on the average, 59% of staff are wasted through fatality or severe accidents, also points to escalating rates of fatalities and disabilities stemming from accidents thus calling for the need to review the existing hazard operations studies (HAZOPS) and hazard identification schemes (HAZIDS) so as to assist in whittling down, as low as reasonably practicable, the perceived unpleasant trend. The author is of the opinion that industrial accident victims, unlike in road traffic accident (RTA), habituate several times before entering the absorbing state.
Authors: Chong Jing Yan, Yan Song
Abstract: Virtual enterprise or e-manufacturing is an advanced and effective manufacturing mode to modern manufacturing enterprises. In these modes, business process has been extended to outer enterprises, i.e. inter organization workflow. In order to achieve a efficient tool for workflow modeling with both simplicity and semantics, matter element is applied to construct a matter element digraph, in which a node is matter element. Then manufacturing service based workflow model can be dynamically changed or composed by matter element transformation. A case is studied to explain the approach presented in this paper.
Authors: Wen Sheng Li, Hua Ming Xing
Abstract: The concept of minus domination number of an undirected graph is transferred to directed graphs. Exact values are found for the directed cycle and particular types of tournaments. Furthermore, we present some lower bounds for minus domination number in terms of the order, the maximum degree, the maximum outdegree and the minimum outdegree of a directed graph.
Authors: Wen Sheng Li
Abstract: The Concept of Negative Signed Domination Number of a Directed Graph Is Introduced. Exact Values Are Found for the Directed Cycle and Particular Types of Tournaments. Furthermore, it Is Proved that the Negative Signed Domination Number May Be Arbitrarily Big for Digraphs with a Directed Hamiltonian Cycle.
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