Papers by Keyword: Graph Theory

Abstract: The solution of the problem of joint cooling of the building and its water heating system, in case of the thermal energy supply termination, is relevant, since only it can determine the real time available to repair crews to restore the operation of the heating system of each object. The article gives a brief description of the algorithms for calculating the non-stationary hydraulic and thermal regime of the heating system and the algorithm for calculating the non-stationary thermal regime of the building. The joint implementation of both algorithms is based on taking into account the influence of the thermal regime of the system and the building on each other at each time step. Linking of thermal processes in a heating system and in a building is carried out taking into account in their thermal balances of the same quantity of heat flowing for a step on time from a heating system element to the room or vice versa. Calculations on the proposed PC program investigated the influence of different factors on the cooling time of the heating system and the whole building.

Abstract: In a deregulated electricity market the generating and distribution companies enter into various levels of contracts for primary energy transaction. In real time, the losses due to these contracts must be economically supplied by Independent system operators (ISOs). Graph Theory is employed in many fields of engineering especially in transmission loss allocation problem to formulate a given network’s behavior. Graph theory based loss allocation method gives satisfactory results over the other existing methods in terms of technical suitability and various transactions. Loop based representation approach is used for the network formulation. Compared to other loss allocation methods, this method distributes losses to the different participants in a lucid manner. In this paper, a comparison of graph theory based loss allocation method over the other existing methods like proportional sharing, Z bus and modified Z bus loss allocation is made. The results are shown for a sample 4 bus system and IEEE14 bus system. The simulation is carried out using MATLAB (R 2014a).

Abstract: In this paper, problem of sequencing of production orders in mixed-model assembly systems is being analysed. The sequencing in such system is mostly addressed as a CSP problem (Car Sequencing Problem) and due to the fact that no optimal method of solution has yet been found it belongs to the NP-hard problems [1,2]. The NP-hardness of the problem has been proven in [3]. The problem connected with proper sequencing arises from the fact that nowadays it’s the clients who have the biggest influence on the sellers offer. The possibility to customize almost each and every product complicates the production management, as instead of having 10 different products, the number of them may grow up to few hundreds [4]. The problem may be especially observed in automotive industry, however recently it may be also met in household appliances industry, as mass customization can be also observed on that market. Each product may differ in labor-effectiveness, and due to the fact of carrying the assembly in linear assembly systems, each unevenness, each transgression of takt time on a single work-station may lead to the line stoppage.

Abstract: We consider the problem of cooperation among a collection of vehicles performing a shared task using intervehicle communication to coordinate their actions. Tools from algebraic graph theory prove useful in modeling the communication network and relating its topology to formation stability. We show that agents can reach consensus if the value of the function is time invariant and we prove our result by taking agents initial state values. The concept of state buffer is also introduced to avoid delays in achieving consensus.

Abstract: A method for fast search of dangerous lines in power flow transferring was put forward. Search the equal-phase parallel lines of the overload line by graph theory and voltage phasor angle. Search the shortest path between the end nodes of the overload line which went through the equal-phase parallel lines. The lines on the paths belonged to the power flow transferring line set, where the lines with high active power flow distribution coefficient were dangerous lines in power flow transferring. The method is more targeted in the search for power flow transferring path. It will not leave out dangerous lines for only looking for the shortest line between the two nodes of the overload line, and it wil not select the redundant lines for searching the K shortest paths between the two nodes of the overload line. This method is simple and accurate with little calculation. The method is verified by simulation analysis based on IEEE 39 and IEEE 118 bus system.

Abstract: This paper proposes a parallel computing method of topological analysis based on the partition of grid model data, and based on the smart grid dispatch control system it design and develop the parallel topology analysis service using the OpenMP shared memory programming model and C/C++ programming language. According to the layering and zoning features of the smart grid dispatch control system, this method divides the grid mode by area and power station. Package the topology search function and do parallel processing for mode data according to different area and power station, which can realize the parallel network topology analysis. The test result on the actual grid shows that this method has good stability and real-time, and it can meet the system online simulation, analysis and control applications requires for the topology analysis.

Abstract: According to the problem that classical graph-based image segmentation algorithms are not robust to segmentation of texture image. We propose a novel segmentation algorithm that GBCTRS, which overcame the shortcoming of existed graph-based segmentation algorithms N-cut and EGBIS. It extract feature vector of blocks using color-texture feature, calculate weight between each block using the neighborhood relationship, use minimum spanning tree method to clustering segmentation. The experimental show that the new algorithm is more efficient and robust to segment texture image and strong edges image.

Abstract: Allocation of spectrum resource is the key for heterogeneous wireless networks. Taking the differences between different types of access networks available channel bandwidth and the communication requirements of users into consideration on the basis of cognitive heterogeneous network spectrum resource allocation algorithm based on graph coloring theory, this paper introduces bandwidth control parameter and proposes a spectrum resource allocation algorithm based on user needs feedback, which improves the utilization and fairness of system spectrum resources.

Abstract: Measuring the influence of academic research publication is an meaningful work in academe. In this paper, the co-author and the citation networks are built to calculate the influence of a researcher and a paper in the way of networks separately with the discussion of further applications. At the beginning, the co-author network is built to determine the influence of co-authors. Then, based on the citations among the papers in the database, we build up the citation network with the help of graph theory. Thirdly, the method is implemented with the application of American Airline network analysis. As the final, the analysis of strengths and weaknesses is conducted.

Abstract: With the increase of electricity consumption,the line-load tends to the limit,and easy to cause line overloads in the system. To solve this problem, a new algorithm to remove the line overloads is proposed in this paper. The algorithm greatly reduces the number of power flow calculation and improves the computational efficiency by using of the method of alternative routes for the sorting. Through the use of multipath search in the algorithm, the situation of regression is been avoided. Test has been performed with the IEEE 30 bus system. Results have been verified the effectiveness and feasibility of the proposed algorithm.