17 results
Search Results
2. Aplicación de la Teoría de Grafos para mejorar la planificación de rutas de trabajo de una empresa del sector de la distribución automática = An application of Graph Theory to improve the planning of work routes for a company in the vending sector
- Author
-
Puchades Cortés, Vanesa, Mula Bru, Josefa, and Rodríguez Villalobos, Alejandro
- Subjects
Teoría de Grafos ,planificación de rutas ,problema del viajante ,sector del vending ,graph theory ,routing planning ,travelling salesman problem ,vending sector ,Applied mathematics. Quantitative methods ,T57-57.97 ,Mathematics ,QA1-939 ,Business ,HF5001-6182 - Abstract
En la actualidad, la gestión de rutas es un aspecto fundamental en las empresas cuya actividad se basa principalmente en el transporte, ya que supone elevados costes de carburantes, mano de obra, etc. En este artículo, se estudia el caso de la empresa Semacaf Máquinas de Café S.L., perteneciente al sector de la distribución automática, que quiere evaluar la efectividad de su política actual de rutas y compararla con la política óptima obtenida mediante las aplicaciones informáticas Grafos y Rutas, basadas en algoritmos pertenecientes a la Teoría de Grafos. En este trabajo se aplica el algoritmo del Problema del Viajante, que se adapta a las características del problema de la empresa y que cumple los objetivos de minimizar los costes anteriormente mencionados, así como de evaluar la política actual de gestión de rutas de la empresa. = Currently, the routing management is an important aspect in those companies whose activity is mainly based on the transport, since it involves high costs of fuel, manpower, etc. In this paper, the case of the company Semacaf Máquinas de Café S.L. is studied. This company belongs to the sector of automatic distribution and pursues to evaluate the effectiveness of its current policy about planning routes and to compare it with the optimal policy obtained through the software applications, Grafos and Rutas, based on algorithms belonging to Graph Theory. In this paper, the Traveling Salesman Problem (TSP) is applied, due to the characteristics of the problem and because it accomplishes the objectives of minimizing the previously mentioned costs, as well as evaluating the current policy of routing management of the company.
- Published
- 2008
3. Influence analysis of real options collaboration network
- Author
-
Hernandes Coutinho Fagundes and Rodrigo Tavares Nogueira
- Subjects
social network analysis ,análisis de redes sociales ,Computer science ,opciones reales ,bibliometrics ,Topology (electrical circuits) ,Graph theory ,Subject (documents) ,bibliometría ,Real options theory ,Popularity ,Data science ,Giant component ,Internationalization ,redes de colaboración ,collaboration networks ,Real options - Abstract
La teoría de opciones reales surgió como una alternativa para valorar las flexibilidades arraigadas en proyectos y ha adquirido popularidad desde finales del siglo xx. A través de métodos bibliométricos y teoría de grafos, este documento crea un análisis de la red de colaboración compuesta por los investigadores de opciones reales, que incluye trabajos científicos de dieciocho años. En este esfuerzo identificamos meticulosamente a los autores y sus alianzas de coautoría, encontrando una topología distinta sin un componente gigante. Al desarrollar modelos no ponderados y ponderados, la red se desenreda y proporciona mediciones a partir de la propensión a la internacionalización y el cálculo de diferentes métricas de impacto, que reconocen a los investigadores más relevantes sobre el tema. Real Options Theory arose as an alternative to valuate flexibilities entrenched in projects and has acquired popularity since the end of the twentieth century. Through bibliometric methods and graph theory, this paper develops an analysis of the collaboration network comprised of Real Options’ researchers, including scientific papers from over the last eighteen years. In this effort, we meticulously identify authors and their co-authorship alliances, finding a distinct topology without a giant component. Developing unweighted and weighted models, the network is unraveled, providing measurement from internationalization propensity and computing different impact metrics, which recognize the most relevant researchers on the subject.
- Published
- 2019
4. Design of a methodology to improve the investment project portfolios in an electric power system
- Author
-
Manfre, Daniel and Brea, Ebert
- Subjects
optimization by simulation ,Monte Carlo method ,método de Monte Carlo ,graph theory ,optimización entera mixta ,optimización mediante la simulación ,mixed integer optimization ,teoría de grafos ,planificación de la expansión de los sistemas eléctricos de potencia ,expansion planning of electric power systems - Abstract
Un Portafolio de Proyectos de Inversión en un Sistema Eléctrico de Potencia (PPISEP) es considerado en este artículo como un conjunto de proyectos de ampliación de la capacidad instalada de un Sistema Eléctrico de Potencia (SEP). Estos proyectos de ampliación pueden consistir en incrementos de las capacidades de las plantas generadoras o de las líneas de transmisión del SEP. El presente artículo desarrolla una metodología que permite mejorar estos PPISEP. Ésta consiste en estimar el momento en el cual los proyectos de inversión deben llevarse a cabo, y la cantidad de energía activa promedio que cada proyecto de inversión debe introducir al SEP, con el fin de mejorar el equilibrio económico de la empresa eléctrica y disminuir el consumo pronosticado no cubierto de energía activa promedio. Debido a que la mejora del PPISEP entra dentro de un problema de optimización, el presente artículo hace uso de la técnica de optimización Algoritmo Simplex Entero Mixto (ASEM) para plantear la resolución de este problema. La metodología desarrollada en este artículo utiliza la simulación por Monte Carlo para modelar las aleatoriedades del SEP. Dicha metodología es presentada en forma de pseudocódigo y ésta es implementada en un ejemplo numérico, cuyos resultados son analizados mediante algunas herramientas estadísticas. An Investment Project Portfolio in an Electric Power System (IPPEPS) is considered in this article as a set of enhancement projects to increase the installed capacity of an Electric Power System (EPS). These enhancement projects can consist of the installed capacity of power plants or transmission lines of the EPS. This paper develops a methodology to improve the IPPEPS. This consists in estimating the time where the investment projects should be carried out, and the amount of average active energy that each investment project must enter to the EPS, in order to improve the economic balance of the electric utility and decrease the forecasted not covered consumption of average active energy. Since the improvement of the IPPEPS falls into an optimization problem, this paper uses the Integer Mixed Simplex Algorithm (IMSA) to solve this problem. The methodology developed in this article uses Monte Carlo simulation to model the randomness of the EPS. This methodology is formulated in pseudocodes and is implemented in a numeric example whose results are analyzed by some statistical tools.
- Published
- 2015
5. Graphing the Self: An application of graph theory to memetic self-mapping in psychotherapy
- Author
-
Lloyd Hawkeye Robertson and Robert Cassin McFadden
- Subjects
self ,self-mapping ,graph theory ,suicide ideation ,memes ,small world networks ,Social Sciences - Abstract
The benefits of using mathematical concepts are frequently overlooked in qualitative inquiry. In this paper Graph Theory (GT) is applied to a series of two dimensional representations of the self used to illustrate the therapeutic progress of a suicidal youth and to a young mother coping with depression. These self-maps are shown to be equivalent to GT networks with the memes of the self-maps corresponding to GT vertices, the pair-wise relationships between memes corresponding to GT edges, and the time evolution of the self-mapping diagrams corresponding to GT sequence analysis. Consideration is given to the notion that the self so mapped functions as a small world network with emotive psychological triggers serving as “long range” connections. The advantages of using an interactive Graphical User Interface and GT metrics for client centered therapy and future research applications in social science are discussed.
- Published
- 2018
- Full Text
- View/download PDF
6. Hashtags 2.0 - An Annotated History of the Hashtag and a Window to its Future
- Author
-
Eduardo Salazar
- Subjects
Social Network ,Hashtags ,Programmable Hashtags ,Information Era ,Graph Theory ,Communication. Mass media ,P87-96 - Abstract
Hashtags are an example of a Folksonomy, a term coined by Van der Val in 2004 to designate any label (or “tag”) that helps in the process of indexing and retrieval of online content. That said, the hash (#) symbol has a long heritage throughout the computer age. This paper makes an attempt to trace that history, since the hash was first used as a technology aid and towards its emergence as a new construct, the hashtag. It was first proposed openly by Chris Messina as simple means to “form groups” on Twitter, mirroring, in some ways, the way in which the # symbol was used on IRC (Internet Relay Chat) to designate “channels” themselves associated to specific topics and content exchange. The San Diego bushfires of October 2007 lead to an organic growth in the adoption of hashtags, growth that has not stopped since, making them ubiquitous in the current Internet age. Be as it may, the popularity of the hashtag made it also a vehicle to understand how information flows. Consequently, there is an incredibly rich literature explaining the mechanics of diffusion through social networks, opening, in the process, a new question: is that all for the hashtag? That’s a question we also attempt to answer by introducing a new construct: the “programmable hashtag” (or p#).
- Published
- 2017
- Full Text
- View/download PDF
7. Controlled Islanding with Special Consideration of Parallel Power System Restoration Constraints
- Author
-
Jairo Quirós-Tortós and Pablo Fernández-Porras
- Subjects
Graph theory ,intentional controlled islanding ,parallel power system restoration ,spectral clustering ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Intentional Controlled Islanding (ICI) can prevent blackouts by splitting the system into islands following a severe disturbance. Post-islanding events, however, might lead to instabilities that can result into blackouts within one or more islands. Although it is critical to ensure that the islands can be restored in the case of local blackouts, this has not been addressed in the literature. To fill this gap, this paper proposes an ICI method that considers not only the typical ICI constraints, but also Parallel Power System Restoration (PPSR) constraints. The traditional islanding problem for minimal power-flow disruption ensuring the typical generator coherency constraint is extended to include at least one blackstart unit within each island and to exclude various branches from possible solutions. To understand the extent to which each island can be restored, the method quantifies the active and reactive power generation available within each island to determine the maximum load that can be picked up. By applying the proposed ICI method, the restoration process can be facilitated and speeded up. Simulation studies on two IEEE test systems are used to demonstrate the effectiveness of the method in determining an islanding solution that considers PPSR constraints with different network topologies and sizes.
- Published
- 2017
- Full Text
- View/download PDF
8. GEODESIC DISTRIBUTION IN GRAPH THEORY: KULLBACK-LEIBLER-SYMMETRIC
- Author
-
José Alejandro González and Marcos Henrique Cascone
- Subjects
Kullback-Leibler information ,graph theory ,geodesic distance ,geodesic distribution ,Mathematics ,QA1-939 - Abstract
Kullback-Leibler information allow us to characterize a family of dis- tributions denominated Kullback-Leibler-Symmetric, which are distance functions and, under some restrictions, generate the Jensen’s equality shown by [1], in this paper denominated Jensen-Equal. On the other hand, [5] and [7] showed that graph theory gives conditions to define a new mea- surable space and, therefore, new distances, in particular, the distance characterized by [2], denominated Geodesic Distance. The interaction of these ideas allow us to define a new distribution, denominated Geodesic Distri- bution which, under graph theory as center and radius of a graph, we can to develop optimization methodologies based in probabilities of attendance. We obtain many applications and the proposal method is very adaptive. To illustrate, we apply this distribution in spatial statistics.
- Published
- 2014
- Full Text
- View/download PDF
9. Mundos pequenos, produção acadêmica e grafos de colaboração: um estudo de caso dos Enanpads Small worlds, academic production and collaborative graphs: a case study of the Enanpads
- Author
-
Mauro Joaquim da Costa Braga, Luiz Flavio Autran Monteiro Gomes, and Marco Aurélio Ruediger
- Subjects
redes sociais ,teoria dos grafos ,comunidades científicas ,endogenia ,social networks ,graph theory ,scientific community ,endogeny ,Political institutions and public administration (General) ,JF20-2112 - Abstract
Utilizando a base de dados dos trabalhos publicados nos Enanpads realizados em 2002-04, este artigo focaliza a área de administração da informação para realizar um estudo exploratório sobre a formação de padrões nas estruturas de disseminação do conhecimento acadêmico no Brasil, apoiado nos conceitos oriundos da análise das redes sociais e conjugados com a base proveniente da teoria dos grafos e em recursos computacionais. Procurou-se mapear os fluxos de informações que possibilitam as trocas de conhecimento através das ligações existentes no meio acadêmico. Os resultados indicam a necessidade de ampliar e estreitar os laços entre os autores, notadamente os que possuem algum grau de centralidade local, no intuito de obter o fortalecimento das instituições de ensino, de forma a quebrar as resistências à produção conjunta entre elas, em detrimento do padrão de reprodução endógena detectado.This article uses the database of papers published in the Enanpad proceedings in the 2002-04 period, focusing in the information management area in order to carry out an exploratory study of the patterns of dissemination of academic knowledge in Brazil. The framework of the study relies is that of graph-theoretical, computational-based social network analysis. The authors then map the information flows that allow knowledge exchanges circulating through the existing connections in the academic environment. Results from the analysis suggest the need for broadening and strengthening linkages among contributing authors. This seems to be most important for authors with some degree of local centrality, because this would probably lead to overcoming any barriers to joint scientific production, as opposed to the prevailing pattern of endogenous production.
- Published
- 2008
- Full Text
- View/download PDF
10. Optimal structure in interconnected dynamical systems (I)
- Author
-
Fausto Posso
- Subjects
interconnected dynamical systems ,component connection model ,hierarchical structures ,graph theory ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Technology (General) ,T1-995 - Abstract
In this paper we study the modeling of interconnected dynamical systems (SDI), under the structural approximation “Component-Connection Model” (CCM). It tries specially the existence of the composite model and his relation with CCM. It has been found that certain structures of connection of SDI, so called “hierarchical structures” predict “a priori” the existence of the composite model and also it is possible to obtain important simplifications both conceptual and numerical on the solution phase of the model. We propose and develop an algorithm to obtain a hierarchical structure based on an arbitrary connection structure. This algorithm is based on graph theory and it is applied with success on two bibliographical examples.
- Published
- 2011
11. Coloración de gráficas suaves
- Author
-
Lara-Velázquez, Pedro, Gutiérrez-Andrade, Miguel Ángel, De-Los-Cobos-Silva, Sergio G., and Rincón-García, Eric Alfredo
- Subjects
teoría de graficas ,90C90 ,05C15 ,teoría de graficas ,soft graph coloring ,graph theory ,coloración de graficas suaves ,coloración sobre vértices ,coloración sobre vértices ,coloring on vertexes ,90C10 ,coloración de graficas suaves - Abstract
ResumenEn este trabajo se propone un modelo de Coloración en Gráficas Suaves donde se colorea con base en ponderaciones sobre las aristas de la gráfica. Se muestra que este modelo es muy flexible e incluye otros problemas similares, tales como los problemas de Coloración Mínima, Coloración Equitativa, Coloración de Gráficas Débiles y Coloración Robusta. Se proponen también un modelo binario lineal de solución y algunas instancias de prueba. AbstractIn this paper a Soft Graph Coloring Model is proposed, which is colored based on weights on the edges of the graph. It is shown that this model is very flexible and includes other similar problems such as Minimal, Equitable, Weak, and Robust Graph Coloring. A linear binary solution model and some test instances are also proposed.
- Published
- 2015
12. Estrategias matemáticas en la ONU
- Author
-
Jordan Lluch, Cristina, Sanabria Codesal, Esther, and Pérez Peñalver, María José
- Subjects
Emparejamientos ,Science ,Graph Theory ,QA1-939 ,Teoría de grafos ,Matching ,MATEMATICA APLICADA ,Modelización ,Mathematics ,Modelling - Abstract
[EN] The matching theory provides concepts and tools necessary to resolve problemes consisting of establishing couples formed by elements of two different sets or belonging to the same set. We use this theory to help the advisory team of the Spanish Ambassador, which elects the speakers who will participate in a preparatory meeting for the annual ministerial review of social and economic conference of the UN., [ES] La teoría de emparejamientos proporciona los conceptos y herramientas necesarios para la resolución de problemas consistentes en establecer parejas entre elementos de conjuntos distintos o dentro de un mismo conjunto. Utilizamos esta teoría para ayudar al equipo asesor del embajador español, encargado de elegir los ponentes que participarán en una reunión preparatoria del examen ministerial anual del congreso económico y social de la ONU, This paper presents the single price multicriteria model applied in order to develop a full ranking of housings. With the application of this model we characterize the set of flats in equilibrium from both the seller and buyer views. Thus we are able to calculate an efficiency index in order to fully rank the flats. It states how in an equilibrium situation both views lead necessarily to inverse rankings. Opposite to other full ranking proposals, our methodology (i) assumes a moderately attitude on behalf of the decision-maker, formulated by means of a strong axiomatic approach, (ii) provides a weight for the criteria regardless of the evaluated housing and the optimistic or pessimistic attitude of the decision-maker and (iii) requires a minimum computational cost. The model is illustrated by a housing sample located in Valencia (Spain).
- Published
- 2012
13. Algunos modelos para planeación y programación en empresas de servicios
- Author
-
Ballesteros Silva, Pedro Pablo and Ballesteros Riveros, Diana Paola
- Subjects
Graph theory ,Customer service ,Teoría de grafos ,Servicio al cliente - Abstract
Se pretende con este artículo hacer una breve descripción e identificación de los aspectos más relevantes de algunos modelos para la planeación y programación de la producción en el sector de los servicios, considerando sus características, medidas de desempeño y objetivos. Igualmente, se muestra un estudio de caso y su solución con una heurística fundamentada en la teoría de grafos. Para esto, se tienen en cuenta sus restricciones, los elementos del sistema y al final se dan a conocer algunas conclusiones que pueden incentivar al lector a profundizar en el tema y adquirir mayores elementos de discusión. It is tried with this paper to do a brief description and identification of the most important aspects of some models for the planning and scheduling of the production in the sector of the services, considering his characteristics, measures of performance and objectives. Also, one is to a study of case and its solution with a heuristic one based on the theory of graphs. For this, they consider their restrictions, the elements of the system and in the end occur to know some conclusions that can stimulate the reader to deepen in the subject and to acquire greater elements of discussion.
- Published
- 2007
14. Análisis cinemático de mecanismos planos por el método de los grafos
- Author
-
Calle Trujillo, Gabriel, Díaz Arias, Alexander, and Henao Castañeda, Edison de Jesús
- Subjects
Graph theory ,Kinematics ,Teoría de grafos ,Cinemática - Abstract
En este artículo se presenta una simplificación metodológica para el análisis cinemático de mecanismos formados a partir de grupos de Assur de segunda clase, por el método de los grafos. Se presenta un planteamiento general del método y la solución de un mecanismo especifico. http://www.utp.edu.co/php/revistas/ScientiaEtTechnica/docsFTP/84026115-119.pdf This paper present a methodological simplification of cinematic analyses of mechanics formed for second type ¿assur¿ groups, using the graphs method. It presents a general planning of the method and a specific solution for a specific mechanism.
- Published
- 2006
15. Measuring labour force variables : the 'labour force survey' (EPA) and the 'working and living conditions survey' (ECVT) in Spain
- Author
-
Muro Romero, Juan de Dios, Raymond, José Luis, Toharia Cortés, Luis, Uriel, Ezequiel, and Universidad de Alcalá. Departamento de Estadística, Estructura Económica y Organización Económica Internacional
- Subjects
ECONOMICS ,Economics ,Categorías de actividad ,Ciencias económicas ,Statistics ,EPA ,Labour force variables ,Estadística ,Teoría de Grafos ,Graph theory ,Encuestas de Poblacion Activa ,Labour force surveys ,ECVT ,CIENCIAS ECONÓMICAS - Abstract
Se aplican las técnicas de la teoría de Grafos para realizar un estudio comparativo de las clasificaciones de la población en relación con la actividad económica en la Encuesta de Población Activa (EPA-76) y en la Encuesta de Condiciones de Vida y Trabajo en España (ECVT), Graph theory is applied in this paper to establish a comparative methodological study between the way labour force surveys in Spain capture the labour market structure. The comparison concerns EPA, the quarterly permanent labour force survey, and ECVT, a sample survey made in fall 1985 with the principal aim of studying the size and main features of the spanish irregular or "hidden" economy
- Published
- 1989
16. El diámetro de ciertos digrafos circulantes de triple paso
- Author
-
Morillo Bosch, M. Paz|||0000-0002-0063-2716, Fiol Mora, Miquel Àngel|||0000-0003-1337-4952, Universitat Politècnica de Catalunya. Departament de Matemàtica Aplicada IV, and Universitat Politècnica de Catalunya. COMBGRAPH - Combinatòria, Teoria de Grafs i Aplicacions
- Subjects
Graph theory ,Teselación ,Grafs, Teoria de ,Diámetro ,05 Combinatorics::05C Graph theory [Classificació AMS] ,Orden ,Digrafo circulante - Abstract
This paper studies some diameter-related properties of the $3$-step circulant digraphs with set of vertices $V=Z_N$ and steps $(\pm a,b)$. More precisely, it concentrates upon maximizing their order $N$ for any fixed values of their diameter $k$. In the proposed geometrical approach, each digraph is fully represented by a T-shape tile which tessellates periodically the plane. The study of these tiles leads to the optimal solutions.
- Published
- 1986
17. Sobre la representación de un conjunto mediante árboles cognitivos
- Author
-
Arcas i Pons, Antoni
- Subjects
Graph theory ,Ciències naturals ,Espais topològics ,Biologia ,Multivariate analysis ,92 Biology and other natural sciences [Classificació AMS] ,Grafs, Teoria de ,Spaces, Topological ,Natural sciences ,Anàlisi multivariable ,62 Statistics::62H Multivariate analysis [Classificació AMS] ,05 Combinatorics::05C Graph theory [Classificació AMS] ,54 General topology::54E Spaces with richer structures [Classificació AMS] - Abstract
En este trabajo se estudia el problema de la representación de un conjunto mediante árboles aditivos, en el sentido de hallar una formalización que permita abordar el mismo desde la perspectiva general de los métodos geométricos de representación del análisis multivariante. In this paper we have studied the problem of the additive tree representation. Our purpose was develop a formal structure that could allow us to analyse that problem from the general perspective of the metric representation method in multivariate data analysis. Moreover, we have studied the relationship between additive tree represen- tations and ultrametric tree representations through this struct ure. On the other hand, this study lends an alternative, from another viewpoint, to the formalitation developed by Buneman (1971).
- Published
- 1987
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.